Pavement Maintenance - Cornell Local Roads Program - Cornell ...

Pavement Maintenance 

Cornell Local Roads Program 

NEW YORK LTAP CENTER


by 

David P. Orr, PE 

Senior Engineer 



416 Riley-Robb Hall 

Ithaca, New York 14853-5701 

Tel: 607-255-8033 

Fax: 607-255-4080 

Email: clrp@cornell.edu 

Web site: www.clrp.cornell.edu 

March 2006 

CLRP No. 06-5

PREFACE 

Millions of dollars are spent each year maintaining and repairing pavements all over New York 

State. Since inadequate drainage is the source of many of the problems, the Cornell Local Roads 

Program offers a one-day course devoted exclusively to drainage. I was fortunate to develop that 

course, Roadway and Roadside Drainage, in 1997. 

Another issue I have seen in my travels around the state is that of selecting the correct pavement 

repair, particularly with regard to pavement surviving winter weather and heavy traffic. In many 

textbooks and training manuals, there is a concentration either on the management of the 

pavement or on the specific repair. While these items are important, I feel it is essential to focus 

on the selection of the repair. Management of highway systems can only be accomplished with a 

thorough knowledge of why pavements fail and what it takes to fix them. 

To this end, this class on Pavement Maintenance was developed. We considered other titles such 

as Pavement Preservation and Pavement Fixes. 

This manual discusses choosing the proper repair techniques for paved and unpaved roads. It 

also goes into more detail on some of the most common asphalt pavement maintenance 

techniques such as patching and chip seals. It is not intended to provide all of the training needed 

to properly select and perform pavement maintenance. It is intended to answer the most common 

questions and to help you get what you expect when it comes to pavement repair. 

David P. Orr, P.E. 

Senior Engineer 


Ithaca, New York 

March 2006 

Cornell Local Roads Program i


ACKNOWLEDGEMENT 

I would like to thank several people for helping out with this manual. Some of them may not 

even realize that they played a role. In 1996, just after I joined the Cornell Local Roads Program, 

Jim Dean, the Town of Orangetown Highway Superintendent, asked me to teach a class on 

pavement maintenance. That class was repeated and upgraded several times, and has evolved 

into this manual and workshop. Ken Osborne and the members of the Liquid Asphalt 

Distributors Association (LADA) have provided insight and help with getting materials and 

examples. Chris Blades and Ed Kearney teach our class on Asphalt Paving Principles. That 

workshop and this one work well as a pair. Finally, I need to thank Lynne Irwin, Director of the 

Cornell Local Roads Program. His lecture in a class on Pavement Engineering gave me the idea 

of developing a class that focusses on understanding the solutions to repairing pavements. 

ii Cornell Local Roads Program

TABLE OF CONTENTS 

Chapter 

1. Introduction............................................................................................................................ 1 

2. Why Roads Fail Prematurely................................................................................................. 5 

3. Repair Techniques ............................................................................................................... 13 

4. Pavement Distresses............................................................................................................. 17 

5. Choosing the Right Repair................................................................................................... 29 

6. Crack Repairs....................................................................................................................... 33 

7. Patching................................................................................................................................ 41 

8. Thin Wearing Courses ......................................................................................................... 47 

Appendix A Crack Treatment Materials ..............................................................................63 

Appendix B Publications......................................................................................................64 

Appendix C Videos ..............................................................................................................65 

Appendix D Resources .........................................................................................................66 

Appendix E NYSDOT Regional Offices .............................................................................68 

Appendix F Glossary ...........................................................................................................69 

Cornell Local Roads Program iii


List of Figures 

Figure 1 Map of NY State towns & cities by population - 2000......................................1 

Figure 2 Spread of wheel load pressure through the pavement .......................................5 

Figure 3 Pavement deflection...........................................................................................6 

Figure 4 High severity alligator cracking.......................................................................18 

Figure 5 Sealed longitudinal cracks ...............................................................................19 

Figure 6 Low severity transverse crack..........................................................................19 

Figure 7 Medium to high severity block cracking .........................................................20 

Figure 8 High severity edge cracking.............................................................................21 

Figure 9 Medium severity rutting...................................................................................22 

Figure 10 Shoving of asphalt surface...............................................................................23 

Figure 11 Potholes caused by poor drainage....................................................................24 

Figure 12 High severity ravelling of asphalt surface .......................................................25 

Figure 13 Bleeding during hot weather............................................................................26 

Figure 14 Polishing of asphalt surface .............................................................................26 

Figure 15 Overlay delamination.......................................................................................27 

Figure 16 Pavement deterioration curve ..........................................................................30 

Figure 17 Pavement repair alternatives............................................................................31 

Figure 18 Crack with high level of edge deterioration.....................................................33 

Figure 19 Basic crack repair configurations.....................................................................35 

Figure 20 Crack sealing creating a safety hazard.............................................................36 

Figure 21 Crack routing ...................................................................................................38 

Figure 22 Heat lance.........................................................................................................39 

Figure 23 Basic wand application of crack sealer............................................................39 

Figure 24 Finishing a crack with a squeegee ...................................................................40 

Figure 25 Cut boundaries .................................................................................................42 

Figure 26 Finished patch ..................................................................................................43 

Figure 27 Self contained spray patch truck......................................................................44 

Figure 28 'Rolling' a cold mix patch.................................................................................46 

Figure 29 Spreading stone for chip seal ...........................................................................47 

Figure 30 Proper spacing of emulsion and chip spreader ...............................................48 

Figure 31 Slurry seal equipment schematic .....................................................................49 

Figure 32 Micropaving equipment schematic..................................................................50 

Figure 33 Chip seal placement .........................................................................................55 

Figure 34 Residual asphalt ...............................................................................................56 

Figure 35 Average Least Dimension of chip seal after curing.........................................57 

Figure 36 Self propelled aggregate spreader....................................................................59 

Figure 37 Spray bar alignment .........................................................................................59 

Figure 38 Spray lap coverage...........................................................................................59 

Figure 39 Improper spacing of emulsion and chip spreader ............................................60 

iv Cornell Local Roads Program

List of Tables 

Table 1 Average distribution of government expenditures on highways in NY ............2 

Table 2 Pavement repair techniques ...............................................................................2 

Table 3 Maintenance activities .....................................................................................29 

Table 4 Pavement repair matrix....................................................................................32 

Table 5 Determining the type of maintenance for cracks .............................................34 

Table 6 Guidelines for crack repairs.............................................................................35 

Table 7 Properties of crack filling materials.................................................................37 

Table 8 Proprietary cold patches on NYS OGS bids, 2005..........................................45 

Table 9 Cost effectiveness of various demand patching methods ................................46 

Table 10 Distresses repaired by selected thin wearing courses ......................................48 

Table 11 Aggregate gradations used for slurry seals (ISSA 1998).................................49 

Table 12 Sieve sizes for common chip seal aggregates (NYSDOT spec.) .....................52 

Table 13 Asphalt emulsions and residual asphalt content ..............................................53 

Table 14 Emulsion application rate adjustments ............................................................58 

Cornell Local Roads Program v

1 - Introduction 

_____________________________________________________________ 

Pavement MANAGEMENT: 

Doing the right repair in the right place, at the right time. 

Pavement MAINTENANCE: 

Doing inexpensive repairs on good roads to keep them good. 

- Foundation for Pavement Preservation 

The proper maintenance of … roads, considering the State at large, is 

unquestionably of more importance than any of the problems that are solved and 

to be solved either in construction or maintenance of more expensive roads. 

- State of New York Department of Highways, 1910 

The pressure on highway and street departments to do more with less is always a concern. 

Whether in the largest city (New York) or the smallest town (Montague in Lewis County), the 

cost of construction and maintenance of highways can be a sore subject. As shown in Table 1, 

the average distribution of government moneys spent on highways in 1997 varies from 2.8 

percent for counties to almost 20 percent for towns. Not too many years ago, the highway 

department was the largest department in many towns and counties and a substantial portion of 

the budget in villages and cities. 

Number of Persons 

Under 2,500 

2,500 to 9,999 

10,000 to 19,999 

20,000 to 49,999 

50,000 and over 

Figure 1 - Map of New York State towns and cities by population, 2000, 

source: New York State Department of Transportation 

Cornell Local Roads Program 1


Table 1 - Average distribution of government expenditures on highways in New York State, 

1997, source: Local Government Handbook 

Function Counties Cities Towns Villages 

Highways 2.8% 5.5% 19.8% 10.2% 

While the portion of the budget spent on highways and streets has decreased, traffic levels have 

increased and the public continues to demand better roads. It is critical that we get the most out 

of every dollar we spend. 

We must spend these limited funds wisely. In many books and manuals, this is defined as 

pavement management. While it is important to do the right repair at the right place at the right 

time, it is cheaper to maintain roads in good shape than it is to fix roads that are broken. 

Pavement maintenance is doing repairs on good roads to keep them good. A good pavement 

maintenance program is usually part of an overall management plan. It can also be used as the 

starting point to develop such a plan. 

One of the most important keys to successful pavement maintenance is to know what the proper 

repair is. This can range from doing nothing to reconstructing the entire road. It may be better to 

do nothing rather than to make a repair that fails prematurely. 

We have all had to make a repair, even when it was not our first choice. In such a case, it is 

important to know what may go wrong and how to reduce the chances of it happening again. 

Understanding the reasons is important to making the correct choice. 

There are many different pavement maintenance techniques. There are even different ways to list 

them. Table 2 shows possible repair techniques for asphalt and gravel surface roads, listed in 

order of increasing cost and durability. Concrete and brick streets are not addressed. 

Asphalt concrete surfaced 

pavements 

Do nothing 

Drainage maintenance 

Crack treatment 

Patching 

Area repairs 

Wearing courses 

Overlays 

Recycling 

Reclamation 

Total reconstruction 

Table 2 - Pavement repair techniques 

2 Cornell Local Roads Program 

Gravel surfaced pavements 

Do nothing 


Blading or grading 

Reshaping 

Patching 

Wearing courses 

Recycling 

Reclamation 

Total reconstruction

1 - Introduction 

This manual focusses mainly on asphalt surface-treated roadways. Almost forty percent of the 

roads in the United States are gravel, but much of the discussion on why roads fail prematurely is 

applicable for all types of road surfaces. For more details on gravel road maintenance, the 

Gravel Roads Maintenance and Design Manual from the South Dakota LTAP Center is a good 

resource. See Appendix B for the the complete publication information, and Appendix D for the 

SD LTAP contact information. 


2 - Why Roads Fail Prematurely 

_____________________________________________________________ 

In a perfect world, pavement would last forever. Unfortunately, this is not the case. Before 

deciding on the proper repair, we need to understand why there may be premature distresses. 

Before discussing why roads fail prematurely, we need to start with, “What is a road?” 

What is a road? 

A road allows transportation from point A to B in all weather and traffic conditions. While a 

basic definition, this does not answer the question of why we build roads. Essentially, we build 

roads to reduce the stress on the native material (i.e., subgrade) under the pavement. To do this, 

we have to place good materials on the subgrade to spread out the load. 

Figure 2 shows how the load is spread out by the pavement. A thicker pavement will result in 

less stress on the subgrade. Figure 3 shows how pavement deflects under a wheel load. As the 

pavement flexes, there will be a combination of compression (pushing) and tension (pulling) 

stress in the pavement. This can eventually lead to cracking due to fatigue. 

Figure 2 - Spread of wheel load pressure through the pavement 

The amount of deflection and stress in the pavement is also related to the amount of moisture in the 

subgrade soils. If the subgrade soils are wet, there will be a great deal of deflection under the wheel 

loads. The deflection will be much less for the same soil when it is well drained. The excess 

moisture in spring thaw will result in higher stresses in the pavement. 

Larger loads and thinner pavements result in more stress on the pavement. Pavements will fail 

sooner than expected if: 

• There are heavier loads than expected 

• There are more loads than expected 

• The pavement is too thin for the traffic loads 

• The materials used in the pavement are weaker than expected 



Understanding fatigue 

Figure 3 - Pavement deflection 

Fatigue is the failure of a material due to repetition of many loads. The larger the load, the fewer 

the number of cycles needed to cause failure. In a pavement, the result is typically cracking or 

rutting. Roads with heavier trucks or weakened pavement during spring thaw are more susceptible 

to fatigue failure. 

To understand this, take a paper clip and bend it back and forth until it fails. To simulate the 

summer, bend it to 45° each time. Count how many cycles it takes to fatigue the paper clip. To 

simulate spring thaw, bend to 90°. A very weak pavement with heavy loads might be like bending 

the paper clip to 180°. 

45° 90° 180° 

We need to build pavements to handle the loads. If the loads are heavy and frequent, we need to 

build a thick, well-drained pavement that does not bend as much. 

Premature failure 

Pavements fail prematurely because of many factors. When boiled down to the basics, there are 

four primary reasons pavements fail prematurely: 

• Failure in design 

• Failure in construction 

• Failure in materials 

• Failure in maintenance 

6 Cornell Local Roads Program


Generally when a road or street fails before we expect it to, one of these four factors is the 

primary cause. Multiple factors can occur, but usually one of the four is the most critical. 

The think system 

Think of a section of highway in your municipality that never seems to last as long as you 

expect. Pick one of the four factors above that you think is most likely to be the prime factor to 

premature failure. As you read the section below, see if your choice stays the same. 

Design 

Most roads are not specifically designed. They have evolved from paths and trails to the 

pavements we have today. This does not mean we need to go out and have a full-blown 

engineering design done for every road repair. In fact, most roads work just fine. 

However, there are still many issues that need to be examined. Do we understand the conditions 

on the road? What is the traffic level? Has anything changed since the last major improvement? 

Is anything likely to change? 

For low-volume roads, the most important design challenge is accounting for weather and 

drainage conditions. If the drainage is done correctly, and the road is built to certain minimums 

of thickness and quality, it should hold up just fine. 

However, there are still many failures due to design. 

Under-designed 

A road that cannot handle the loads is under-designed. This could be due to a failure to 

account for conditions such as an increase in truck traffic. For instance, new roads to 

industrial and commercial areas should be designed. Before the municipality takes over a 

road, it must feel confident the road will last as long as possible. Get an engineer to help 

design the road if you are not sure. Ask for a professional engineering certification that 

the road will last the desired number of years. 

Failure to account for conditions 

Even if the road is built to a quality standard, there may be premature failure if any 

conditions remain unaccounted for in the design. The condition assessment problem that 

leads to the most premature failures is a lack of good drainage. This is not a construction 

or materials problem in many cases. When inspecting the road before work is done, the 

quality of the drainage MUST be assessed. Failure to do so will almost always result in 

premature failure. 

Changes after construction 

If you build it, they will come. As soon as you build a smooth section of pavement, 

vehicles that had detoured in the past may suddenly decide to use the new roadway. If 

you failed to anticipate this increased traffic, your road may fail too soon. This can be 

especially bad if there is extra truck traffic in the spring during the thaw. 



Examples of failure in design 

• Overlay too thin for traffic load (Too thick is also not desirable. It wastes money.) 

• Failure to account for a spring in the middle of the roadway 

• Use of a chip seal over a badly cracked road 

• Selecting crack seals to fix badly deteriorated cracks 

• Using asphalt cement stabilizer when the fines content is too high 

(above about 12 percent) 

Construction 

Just as design can lead to premature failure, poor quality construction can cause a roadway to fail 

early. Many construction failures do not appear as defects for several years, so it can be difficult 

to determine the reason for the failure. Whether the work is done in-house or by contract, it is 

important to get the job done right. 

If you are doing the work yourself, are you ready? Has the crew been trained? What training do 

they need and where can you get the training? Municipalities have some of the best snowplow 

crews anywhere. Part of that expertise is experience. You do something enough and you get 

pretty good at it. Part of the expertise is training. Riding with that old-timer can be some of the 

best training you can get. 

If you are contracting the work, are you ready? Do you need an inspector for the work? Is the 

inspector trained and ready to make sure the municipality gets what they pay for? What kind of 

contract are you using? 

Construction may be the most difficult step because there are so many questions to be asked and 

answered. The problem with not asking the questions is that we usually do not get a second 

chance to do the work again. 

Fortunately, experience is a great teacher, and for most operations some basic training and 

practice is enough to make sure the work is done right. Complicated and specialized work can 

still be problematic and failures due to construction can occur. 

Poor workmanship 

The best laid plans often go astray. If the work is not done properly then it may not last. 

A very common problem in culvert installation is the failure to compact the backfill in 

thin even lifts. It may be faster to put in thick lifts, but coming back to fix the problem 

after settlement occurs is not a good alternative. Training and pride in your work go a 

long way towards overcoming workmanship issues. 

Using incorrect equipment 

Everyone knows you should hit a nail with a hammer, yet how many of us have used a 

wrench instead? Using the wrong tool in pavement maintenance can lead to premature 

failure. A rubber-tired roller should be used on a chip seal. A steel drum roller can crush 

and break the aggregate. NOT using a piece of equipment can also cause problems. 

Leaving gravel unrolled because no roller is available is a bad solution. 



Using equipment improperly 

Even if you have the right piece of equipment, it is important to use it correctly. A 

distributor with misaligned fans will lead to streaking. Using a compressor to blow out 

cracks can put water into the cracks. Know what a piece of equipment is for and how to 

use it properly. 

Failure to follow plans 

Do you have plans? Engineering drawings are not required for pavement maintenance, 

but writing down the steps and having a plan is a valuable tool. Examples of items in a 

good plan include stakeout, detours, materials, construction steps, and plans in case of 

poor weather. Without a plan, how do you know whether anything was done incorrectly? 

Lack of training 

Lynne Irwin likes to say: “How do you know what you don’t know, if you don’t know 

that you don't know it?” A crew cannot be expected to do something if they do not know 

how. Provide training for everyone. It can be on-the-job, tailgate talks over breaks, hourlong 

training at an association meeting, or all-day training from the Cornell Local Roads 

Program or a vendor. 

Wrong time of year or poor weather 

We cannot control the weather, but we can account for it. A surface treatment placed in 

October is not likely to work as well as one placed in July. On the other hand, if it rained 

during construction in July, it is not likely to do very well either. Know the limitations for 

the repair. You may have to do the work anyway, but you will be better prepared to 

overcome the problems that may arise. 

Examples of failure in construction 

• Failure to compact cold patch with the truck tire 

• Failure to place the aggregate in a chip seal before the asphalt emulsion breaks 

• Using an air compressor without an oil/water separator to clean cracks (can introduce 

water and cause a loss of bond) 

• Paving over a base that is not properly prepared 

• Doing any work with asphalt emulsions after late October (or on any cold day) 



Materials 

Using the wrong material in the right place or the right material in the wrong place can lead to 

premature failure. Sometimes the problems are obvious. Sometimes the problem does not appear 

to be related to the material choice. Backfilling an underdrain trench with large stone is actually 

a materials problem. The stones will retain silt particles brought in by the drained water and will 

lead to premature plugging of the pipe. Be sure to select the correct material for the job. 

Wrong material 

The wrong material will lead to premature failure. Using a dirty gravel base is a classic 

example. The use of the less expensive material can lead to much larger expenses in the 

future. Understand what the limitations of a particular product are before you use it. Ask 

the vendor, other highway departments, or the New York State Department of 

Transportation. Get a clear picture of the best material for the job. 

Material does not meet specifications 

Once you select the material, make sure it meets specifications. By some estimates, 1/4 of 

the wire in the main cables of the Brooklyn Bridge did not meet the specifications. When 

the contractor was caught, the extra expense of more cable was paid out of their contract. 

Some failures are due to a material not meeting specifications. One recommendation is to 

always sample the materials on site. It is not always possible to go back and get a sample 

after the construction is complete. 

Material installed incorrectly 

If material is put in incorrectly, there can be premature failure. Is this a construction issue 

or a material issue? It could be both. It should be neither. Sometimes the problem is 

failure to install the item using a newer technique. For instance, Superpave asphalt 

concrete needs to be rolled differently than older Marshall Mix design asphalt concretes. 

Incompatibility with other materials 

Aggregate charge incompatibility is cited almost every time a chip seal fails. In reality, it 

almost never occurs. Much more common is using a dusty stone that does not adhere to 

the asphalt emulsion. When this problem occurs, the consequences can be dramatic. 

Examples of failures in materials 

• Chip sealing over a good quality surface gravel (a good surface gravel has too 

many fines to be a base gravel) 

• Using an asphalt emulsion to seal cracks 

• Using a cheaper cold patch that may last only a few hours 

• Using a dusty or wet aggregate in surface treatment operations 



Maintenance 

The most common maintenance problem is that not enough maintenance is done. This is a 

budgetary, planning, and communication issue that is sometimes very difficult to overcome. 

Once we decide to perform maintenance we need to remember that ALL maintenance techniques 

can be designed to fit the conditions and need to be constructed properly using the correct 

materials. Premature failure of pavement maintenance is usually a failure of design, construction, 

or material. 

Design 

The most common design issue is a lack of design. The first step in design is selecting the 

correct repair to fix the problem. In too many cases, the choice of repair is made for nontechnical 

reasons. In addition, many maintenance repairs are made without any design. 

Even a chip seal can be designed to obtain the best result for the municipality. Knowing 

what needs to be done to get the right repair is one of the most critical steps in the design 

of pavement maintenance. 

Construction 

Once a technique has been chosen, it needs to be done correctly. The failure to construct 

the maintenance repair properly is a major cause of premature failure. A classic example 

is the lack of truck tire rolling of cold mix patch in the winter. Instead of lasting several 

months, it lasts less than a day. 

Material 

Using the correct material is critical. It may be less expensive to buy cheaper gravel, 

patch, or emulsion, but can you afford the cost of replacement if it fails prematurely? 


3 - Repair Techniques 

_____________________________________________________________ 

There are many different pavement maintenance techniques. Before deciding which technique to 

use, make sure you know all of the possible choices. Some problems can only be solved with 

certain techniques. The list below describes the basic repairs that need to be in your pavement 

repair toolbox. 

All Pavements 

Do nothing 

This is the most common repair choice, because of cost. It is used whenever economics dictate 

that no better choice exists. It is used on good and bad roads. A brand new road needs no repairs. 

On a poor, badly cracked surface, the best technique may be to do nothing. It may be better to 

leave a road in rough shape than to cover over the problem and have it recur almost immediately. 


This is absolutely critical to allow roads to last as long as possible. Drainage is the single most 

common problem that leads to premature failures. For more details on drainage, refer to the 

Cornell Local Roads Program manual, Roadway and Roadside Drainage (see Appendix B). 

Asphalt Surfaced Pavement 

Crack repairs 

When cracks are narrow (1/4 inch to 1 inch) and not deteriorated on the edge, crack repairs are a 

good alternative. Crack repairs generally fall into two categories of work: sealing and filling. 

Sealing prevents the intrusion of water and debris into a working crack. A working crack is one 

that moves noticeably (more than an eighth of an inch) due to weather or traffic loads. Filling 

reduces the infiltration of water into a non-working crack. 

Patching 

Patching is a year-round activity that is done to keep road surfaces drivable. Most patching is 

done to fill potholes. Ruts, slippage and other pavement defects may also be fixed best by 

patching. Patching does not fix base problems. Types of patches include: cold asphalt “throw and 

roll,” hot asphalt “semi-permanent,” and spray patching. Patching is very economical if done 

properly. 

Area repairs 

Unlike patching, area repairs involve a more extensive repair. An area repair involves a cut out 

and replacement of a bad section of a road or street. It is relatively expensive for the area 

repaired, but since it fixes any base problems and is not wasteful, it can be the best alternative for 

roads with small areas of distress. 



Thin wearing courses 

Sometimes called surface treatments or seals, there is a large family of alternatives that fall into 

the field of a thin wearing course. They are generally less than one inch thick. This large variety 

of repairs is used to waterproof the pavement, restore skid resistance, and restore oxidized 

surfaces. Some surface treatments can fill minor ruts. Cracks and other defects will reflect 

through. Thin wearing courses do not add any structural strength. 

Overlays 

Generally greater than one-inch thick, an asphalt concrete overlay adds strength and can correct 

minor ride defects. Good timing is critical, due in part to the relatively high expense versus other 

maintenance activities. In an urban area, loss of curb reveal can be a problem. A tack coat is an 

important step to help make sure the technique has as much chance of success as possible, 

Details of overlay construction can be found in the Cornell Local Roads Program manual, 

Asphalt Paving Principles (see Appendix B). 

Recycling 

Recycling is the reuse of the asphalt surface, but it does not usually reuse the base. This 

environmentally-friendly technique fixes cracks and restores the surface, but it does not fix any 

base quality or drainage problems. Any isolated base or drainage problems should be repaired 

prior to recycling. 

Reclamation 

Reclamation or stabilization improves the base, as opposed to recycling, which does not. This is 

done via the addition of aggregates or chemicals to improve the quality of the base. When 

completed properly, it provides an almost new road. Reclamation can be very cost-effective, but 

the choice of stabilizing agent is very critical. 


This is a very expensive technique, but it may be the only option for a badly deteriorated road. 

Total reconstruction can be cost-effective if done in conjunction with utility replacement. This 

choice is usually a last resort. 

Gravel Surfaced Pavements 

Dust control 

Dust palliatives (emulsions, wood lignins, and salts) are used to keep the dust on the surface of 

the pavement and to improve safety for the traveling public. As opposed to stabilization, dust 

control is the primary reason for application and generally no working of the surface is needed. 

In many cases, dust control operations are scheduled to coincide with blading or grading. 

Blading or dragging 

A grader routinely needs to be used to resmooth a gravel surface. This is done with the blade of 

the grader set to vertical with a slight down pressure. Going slow is the key to success. 


3 - Repair Techniques 

Sometimes this is called dragging, after the historical practice of using a horse-drawn wooden 

drag to perform the same function. 

Reshaping 

Reshaping and grading are done when blading is not enough. This generally requires pulling the 

gravel material into a windrow and respreading with the grader. Rolling the surface will improve 

the durability of this repair. 

Patching and area repairs 

For gravel roads, most patching is done in conjunction with other work. Scarify the material in 

the area needing patch to a depth of an inch more than the deepest pothole. Filling in potholes on 

gravel roads is usually not successful. 

Stabilization 

Usually one of the highest levels of repair on a gravel road, stabilization involves using 

chemicals or aggregate to help improve the quality of the material in the pavement. Asphalt 

emulsion, portland cement, calcium chloride, and salt have all been used as chemical additives. 

The choice of additive is critical to the success of the repair. 

Overlays and surface treatments 

Placing an asphalt overlay or surface treating the gravel is sometimes necessary to deal with 

increased traffic. When performing this repair, be sure the gravel surface does not have too many 

fines. If the fines content is above eight percent, the new surface will probably trap moisture and 

fail prematurely. 


As with asphalt surfaced roadways, total reconstruction is a very expensive technique, but it may 

be the only option. For most gravel roads, this is usually done only when the road will be paved 

with asphalt. 


4 - Pavement Distresses 

_____________________________________________________________ 

To understand which repair to choose, it is important to understand the distresses that occur in a 

pavement. Some repairs do not fix certain distresses. Since this manual concentrates on asphalt 

maintenance techniques, only asphalt surface distresses are listed below. For gravel roads, see 

the Federal Highway Administration (FHWA) publication, Problems Associated with Gravel 

Roads. More detailed information on asphalt pavement distress is available in the Distress 

Identification Guide from the Long-Term Pavement Performance Program. See Appendix B. 

The severity and extent of a distress determine the proper repair. If a distress covers more than 

one-third of the pavement surface, the entire roadway may need to be repaired. If the distress is 

isolated to a couple of small areas, then spot repairs may fix the problem. Low severity distresses 

usually require less extensive repairs. For example, a thin wearing course may seal fine cracks of 

low severity. Once the distress is very severe, crack repairs may not be enough to properly fix it. 

The four major categories of common asphalt pavement surface distresses are: 

1. Cracking 

2. Surface deformation 

3. Disintegration (potholes, etc.) 

4. Surface defects (bleeding, etc.) 

Cracking 

Cracks in asphalt pavements can take many forms. The most common types of cracking are: 

1. Fatigue cracking 

2. Longitudinal cracking 

3. Transverse cracking 

4. Block cracking 

5. Slippage cracking 

6. Reflective cracking 

7. Edge cracking 

Fatigue cracking (Alligator cracking) 

Fatigue cracking is commonly called alligator cracking. This is a series of interconnected cracks 

creating small, irregular shaped pieces of pavement. The cracking pattern gives the appearance 

of alligator skin or chicken wire. 



It is caused by failure of the surface layer or base due to repeated traffic loading (fatigue). 

Eventually the cracks lead to disintegration of the surface, as shown in Figure 4. The final result 

is potholes. Alligator cracking is usually associated with base or drainage problems. 

Small areas may be fixed with a patch or area repair. Larger areas require reclamation or 

reconstruction. Drainage must be carefully examined in all cases. 

Figure 4 - High severity alligator cracking 

Longitudinal cracking 

Longitudinal cracks are long cracks that run parallel to the center line of the roadway. These may 

be caused by frost heaving or joint failures, or they may be load induced. Understanding the 

cause is critical to selecting the proper repair. 

Multiple parallel cracks may eventually form from the initial crack. This phenomenon, known as 

deterioration, is usually a sign that crack repairs are not the proper solution. 

Filling or sealing longitudinal cracks can work if the cracks are narrow and not deteriorated too 

much. Figure 5 shows sealed longitudinal cracks. Multiple cracks may require patching or area 

repairs to fix the problem. 


Figure 5 - Sealed longitudinal cracks 


Transverse cracks 

Transverse cracks form at approximately right angles to the centerline of the roadway. They are 

regularly spaced and have some of the same causes as longitudinal cracks. Transverse cracks will 

initially be widely spaced (over 20 feet apart). They usually begin as hairline or very narrow 

cracks and widen with age. If not properly sealed and maintained, secondary or multiple cracks 

develop, parallel to the initial crack. 

The reasons for transverse cracking, and the repairs, are similar to those for longitudinal 

cracking. In addition, thermal issues can lead to low-temperature cracking if the asphalt cement 

is too hard. Figure 6 shows a low-severity transverse crack. 

Figure 6 - Low severity transverse crack 



Block cracking 

Block cracking is an interconnected series of cracks that divides the pavement into irregular 

pieces. This is sometimes the result of transverse and longitudinal cracks intersecting. They can 

also be due to lack of compaction during construction. 

Low severity block cracking may be repaired by a thin wearing course. As the cracking gets 

more severe, overlays and recycling may be needed. If base problems are found, reclamation or 

reconstruction may be needed. Figure 7 shows medium to high severity block cracking. 

Figure 7 - Medium to high severity block cracking 

Slippage cracking 

Slippage cracks are half-moon shaped cracks with both ends pointed towards the oncoming 

vehicles. They are created by the horizontal forces from traffic. 

They are usually a result of poor bonding between the asphalt surface layer and the layer below. 

The lack of a tack coat is a prime factor in many cases. Repair requires removal of the slipped 

area and repaving. Be sure to use a tack coat in the new pavement. 

Reflective cracking 

Reflective cracking occurs when a pavement is overlaid with hot mix asphalt concrete and cracks 

reflect up through the new surface. It is called reflective cracking because it reflects the crack 

pattern of the pavement structure below. 

As expected from the name, reflective cracks are actually covered over cracks reappearing in the 

surface. They can be repaired in similar techniques to the other cracking noted above. Before 

placing any overlays or wearing courses, cracks should be properly repaired. 


Edge cracking 


Edge cracks typically start as crescent shapes at the edge of the pavement. They will expand 

from the edge until they begin to resemble alligator cracking. This type of cracking results from 

lack of support of the shoulder due to weak material or excess moisture. They may occur in a 

curbed section when subsurface water causes a weakness in the pavement. 

At low severity the cracks may be filled. As the severity increases, patches and replacement of 

distressed areas may be needed. In all cases, excess moisture should be eliminated, and the 

shoulders rebuilt with good materials. Figure 8 shows high severity edge cracking. 

Figure 8 - High severity edge cracking 

Surface deformation 

Pavement deformation is the result of weakness in one or more layers of the pavement that has 

experienced movement after construction. The deformation may be accompanied by cracking. 

Surface distortions can be a traffic hazard. 

The basic types of surface deformation are: 

1. Rutting 

2. Corrugations 

3. Shoving 

4. Depressions 

5. Swell 



Rutting 

Rutting is the displacement of pavement material that creates channels in the wheel path. Very 

severe rutting will actually hold water in the rut. Rutting is usually a failure in one or more layers 

in the pavement. The width of the rut is a sign of which layer has failed. A very narrow rut is 

usually a surface failure, while a wide one is indicative of a subgrade failure. Inadequate 

compaction can lead to rutting. Figure 9 shows an example of rutting due to subgrade failure. 

Figure 9 - Medium Severity Rutting 

Minor surface rutting can be filled with micropaving or paver-placed surface treatments. Deeper 

ruts may be shimmed with a truing and leveling course, with an overlay placed over the shim. If 

the surface asphalt is unstable, recycling of the surface may be the best option. If the problem is 

in the subgrade layer, reclamation or reconstruction may be needed. 

Corrugation 

Corrugation is referred to as washboarding because the pavement surface has become distorted 

like a washboard. The instability of the asphalt concrete surface course may be caused by too 

much asphalt cement, too much fine aggregate, or rounded or smooth textured coarse aggregate. 

Corrugations usually occur at places where vehicles accelerate or decelerate. 

Minor corrugations can be repaired with an overlay or surface milling. Severe corrugations 

require a deeper milling before resurfacing. 

Shoving 

Shoving is also a form of plastic movement in the asphalt concrete surface layer that creates a 

localized bulging of the pavement. Locations and causes of shoving are similar to those for 

corrugations. Figure 10 shows an example of shoving. 

Repair minor shoving by removing and replacing. For large areas, milling the surface may be 

required, followed by an overlay. 


Figure 10 - Shoving of asphalt surface 


Depressions 

Depressions are small, localized bowl-shaped areas that may include cracking. Depressions 

cause roughness, are a hazard to motorists, and allow water to collect. Depressions are typically 

caused by localized consolidation or movement of the supporting layers beneath the surface 

course due to instability. 

Repair by excavating and rebuilding the localized depressions. Reconstruction is required for 

extensive depressions. 

Swell 

A swell is a localized upward bulge on the pavement surface. Swells are caused by an expansion 

of the supporting layers beneath the surface course or the subgrade. The expansion is typically 

caused by frost heaving or by moisture. Subgrades with highly plastic clays can swell in a 

manner similar to frost heaves (but usually in warmer months). 

Repair swells by excavating the inferior subgrade material and rebuilding the removed area. 

Reconstruction may be required for extensive swelling. 

Disintegration 

The progressive breaking up of the pavement into small, loose pieces is called disintegration. If 

the disintegration is not repaired in its early stages, complete reconstruction of the pavement may 

be needed. The two most common types of disintegration are: 

1. Potholes 

2. Patches 



Potholes 

Potholes are bowl-shaped holes similar to depressions. They are a progressive failure. First, 

small fragments of the top layer are dislodged. Over time, the distress will progress downward 

into the lower layers of the pavement. Potholes are often located in areas of poor drainage, as 

seen in Figure 11. 

Potholes are formed when the pavement disintegrates under traffic loading, due to inadequate 

strength in one or more layers of the pavement, usually accompanied by the presence of water. 

Most potholes would not occur if the root cause was repaired before development of the pothole. 

Repair by excavating and rebuilding. Area repairs or reconstruction may be required for 

extensive potholes. 

Figure 11 - Potholes caused by poor drainage 

Patches 

A patch is defined as a portion of the pavement that has been removed and replaced. Patches are 

usually used to repair defects in a pavement or to cover a utility trench. Patch failure can lead to 

a more widespread failure of the surrounding pavement. Some people do not consider patches as 

a pavement defect. While this should be true for high quality patches as is done in a semipermanent 

patch, the throw and roll patch is just a cover. The underlying cause is still under the 

pothole. 

To repair a patch, a semi-permanent patch should be placed. Extensive potholes may lead to area 

repairs or reclamation. Reconstruction is only needed if base problems are the root source of the 

potholes. 


Surface defects 


Whereas the previous types of distress are mostly related to the supporting layers beneath the 

surface, surface defects are related to problems in the surface layer. The most common types of 

surface distress are: 

1. Ravelling 

2. Bleeding 

3. Polishing 

4. Delamination 

Ravelling 

Ravelling (see Figure 12), is the loss of material from the pavement surface. It is a result of 

insufficient adhesion between the asphalt cement and the aggregate. Initially, fine aggregate 

breaks loose and leaves small, rough patches in the surface of the pavement. As the 

disintegration continues, larger aggregate breaks loose, leaving rougher surfaces. Ravelling can 

be accelerated by traffic and freezing weather. Some ravelling in chip seals is due to improper 

construction technique. This can also lead to bleeding. Repair the problem with a wearing course 

or an overlay. 

Figure 12 - High severity ravelling of asphalt surface 

Bleeding 

Bleeding is defined as the presence of excess asphalt on the road surface which creates patches 

of asphalt cement. Excessive asphalt cement reduces the skid-resistance of a pavement, and it 

can become very slippery when wet, creating a safety hazard. 

This is caused by an excessively high asphalt cement content in the mix, using an asphalt cement 

with too low a viscosity (too flowable), too heavy a prime or tack coat, or an improperly applied 

seal coat. Bleeding occurs more often in hot weather when the asphalt cement is less viscous 

(more flowable) and the traffic forces the asphalt to the surface. Figure 13 shows an example of 

bleeding during hot weather. 



In some cases, a repair can be made by applying hot sand or slag to blot up the excess asphalt. 

This is a very difficult problem to solve. It sometimes requires removing the bleeding pavement 

and placing a new surface. A thin wearing course will only solve the problem temporarily. The 

bleeding asphalt will eventually work its way upward. 

Figure 13 - Bleeding during hot weather 

Polishing 

Polishing is the wearing of aggregate on the pavement surface due to traffic (see Figure 14). It 

can result in a dangerous low friction surface. A thin wearing course will repair the surface. 

Delamination 

Figure 14 - Polishing of asphalt surface 

Delamination is a failure of an overlay due to a loss of bond between the overlay and the older 

pavement (see Figure 15). Common causes of delamination include: wet or dirty surface during 

paving of the overlay, failure to use a tack coat, or poor compaction of the overlay. Proper 

paving techniques, including cleaning the surface and use of tack coat, will reduce the chances of 

delamination. 


Figure 15 - Overlay delamination 



5 - Choosing the Right Repair 

_____________________________________________________________ 

According to the Foundation for Pavement Preservation, pavement maintenance involves doing 

the right treatment, at the right place, at the right time. To achieve this, good management and an 

understanding of the choices are required. 

For a given set of conditions, at a given time, there is usually one best repair. If a road needs an 

overlay, a chip seal will not suffice. If crack repairs will do the job, there is no good reason to 

place a more costly slurry seal. Sometimes the wrong choices are made due to politics, citizen 

complaints, or lack of money. If such choices are made, it is important to understand why they 

were made and what the consequences are. 

Maintenance activities 

There are four different categories of maintenance activities: demand, routine, corrective and 

reconstructive. 

Table 3 explains how these different activities fit into a pavement management plan. Some can 

be performed before significant deterioration occurs. An example is a chip seal done before 

cracks develop. Preventive maintenance must be done before even moderate cracking occurs, or 

it will not last as long as it should. 

Type of 

maintenance 

Table 3 - Maintenance activities 

Planned? 

Performed before 

deterioration? 

Extends 

pavement life? 

Demand No No Not necessarily 

Routine Yes Not necessarily Sometimes 

Preventive Yes Yes Yes 

Corrective Generally No Yes 

Demand maintenance: Performing a technique to correct a hazard or meet a service request. 

Pothole patching in the spring is the most common form of demand maintenance. 

Routine maintenance: Performed on a routine basis for operational reasons. Examples include 

mowing grass, cutting shoulders, and striping centerlines. 



Preventive maintenance: Application of a treatment before significant deterioration occurs. It 

typically extends the life of the pavement and is usually planned. Surface treatments are usually 

considered preventive maintenance. 

Corrective maintenance: Fixes pavement failures after they have occurred. A semi-permanent 

area patch is a form of corrective maintenance. A truing and leveling layer to fill minor ruts, with 

a follow up overlay, is another example. Corrective maintenance generally costs more than 

preventive or routine maintenance. 

Planned maintenance is generally preferred to unplanned (demand) maintenance, and preventive 

maintenance is preferred to corrective maintenance. Figure 16 shows the relationship between 

condition and the life of the pavement. The pavement starts in very good shape and deteriorates 

slowly at first. Maintenance repairs done early in the life of the pavement are much less 

expensive. 

Figure 17 shows the relationship between pavement condition and the various levels of 

maintenance. These two figures show that routine and preventive maintenance are the most 

economical options. Reconstruction techniques are the most expensive, and are usually done 

when there is no other choice. Although not shown in Figure 17, there are times in the life of a 

pavement when the best alternative is to do nothing. This is usually when the pavement is not a 

candidate for maintenance, and rehabilitation or reconstruction are not yet justifiable. 

Figure 16 - Pavement deterioration curve 


Figure 17 - Pavement repair alternatives 

5 - Choosing the Right Repair 

Selecting the repair 

The first step is to evaluate the road. Divide the road network into segments, and do a condition 

survey on each segment. A condition survey documents the extent and severity of each type of 

pavement distress. Using the results of the condition survey, determine the possible pavement 

repairs. During the evaluation, ask the following questions: 

What kind of maintenance can fix the defects found? 

What repair, if any, will extend the life of the pavement? 

Which maintenance technique will be the most cost effective? 

Table 4 shows a basic matrix to help select the proper repair. The table only shows which repairs 

may be used to fix a given distress at a reasonable price. Generally, the less expensive solutions 

will be in the lefthand columns. Within a treatment category, specific operations may not fix the 

distress in question. One example is a fog seal, which will not restore skid resistance, due to low 

friction. In actual field evaluation, other factors will need to be taken into account. 



Table 4 - Pavement repair matrix 

Repair Treatment Category 

Overlays Recycling Reclamation Reconstruction 

Thin wearing 

courses 

Patching 

Crack 

treatments 

Average duration 3-5 years 1-10 years 3-10 years 5-15 years 10-20 years 15-50 years 25-50 years 

$3.00-7.50/s.y $40.00- 

50.00/s.y. 

$2.75 /in./s.y. $1.00- 

2.00/in./s.y 

$0.60- 

2.00/s.y. 

$1.00- 

5.00/s.y. 

$0.25- 

1.75/l.f. 

Average unit cost 

(2005 prices) 

Distress to be repaired 

Low skid resistance X X 

Raveling X X X 

X X 

Bleeding X 2 

Rutting X 1 X 4 X X X 

Low severity cracks X 3 X 

Moderate severity cracks X 3 X 5 

High severity cracks X X X X 

Potholes X X 


Roughness X 4 X X 

1 - Micropaving and Novachip will fill some ruts. 

2 - Bleeding may reappear after a few years. 

3 - See Chapter 6 to help determine which cracks are good candidates for repairs. 

4 - Overlays with a shim layer added may be used to fill ruts and improve ride quality. 

5 - Cracks will reflect through unless crack repairs are completed first.

6 - Crack Repairs 

_____________________________________________________________ 

Crack repairs are the proper and timely maintenance of cracks using sealing or filling techniques 

to extend pavement life. Crack repairs are very cost effective if done properly. A crack repair 

program begins by determining if crack repairs are suitable for the type of distress. 

Determining Type of Maintenance 

The first step is to inspect the roadway and examine the cracking. Two different factors need to 

be examined: crack density and the level of edge deterioration. The width of the crack also needs 

to be determined. 

Crack density is a subjective term describing the spacing of the cracks. If there are only a few 

cracks along the length of roadway, then the density is low. If there are cracks over the full 

length of the pavement, the density is high. If you are not sure, the density is probably moderate. 

Edge deterioration is a measure of the condition of the cracks. Spalling, secondary cracks, 

cupping, and faulting are all examples of edge deterioration. A single transverse crack may be 

low in density. A badly deteriorated single crack is still low in density, however, it is not a 

candidate for crack repairs. If the edge is deteriorated too much, crack repairs will not be 

successful, and patching or area repairs are needed. 

Crack width is important to determine, if the repair is to be successful. If the crack width is less 

than 1/4 inch (the width of a pencil eraser), then the crack is too narrow for sealing and filling. A 

crack this size is not wide enough to allow the repair material to enter and function. Narrow 

cracks may be surface treated. Alternatively, they can be widened by routing or sawing. 

Figure 18 shows an isolated crack with a large amount of edge deterioration. The initial crack 

has spawned many secondary cracks. If all the cracks were combined together, the width would 

be significantly more than one inch. This is a good candidate for patching. 

Figure 18 - Crack with high level of edge deterioration 



Table 5 shows how crack density and edge deterioration can be used to select the proper type of 

maintenance. In the table, rehabilitation includes recycling and reclamation. Be sure any 

drainage issues are resolved when choosing this option. In the case of low density, moderate 

level cracking, crack repairs may not be cost effective. Pavement should be evaluated on a case 

by case basis. 

Table 5 - Determining the type of maintenance for cracks 

Average level of edge deterioration 

Crack 

Low 

Moderate 

High 

Density 

(0-25%) (26-50%) (51-100%) 

Low Nothing Crack repair? Patching 

Moderate Crack repair Crack repair Patching 

High Surface treatment Surface treatment Rehabilitation 

Sealing versus Filling 

There are two distinct techniques used to repair cracks: sealing and filling. 

• Crack sealing 

The placement of specialized materials either above or into working cracks using 

unique configurations to prevent the intrusion of water and debris into the crack. 

Working cracks are defined as those that experience significant horizontal 

movements, generally greater than about 1/8 inch over the course of the year. 

Working cracks are generally more widely open during winter months, and less 

open in summer months. Cold weather causes the pavement surface to contract, 

which opens the cracks. 

• Crack filling 

The placement of materials into nonworking cracks to reduce infiltration of water 

and to reinforce the adjacent pavement. 

It is important to remember that sealing uses more flexible materials than filling. This allows the 

seal to move with the crack. Sealing material is more expensive, but is usually worth the extra 

money. Substantial savings can result if the cracks are not moving. 

Table 6 shows the basic guidelines for choosing between crack sealing and crack filling. 


Table 6 - Guidelines for crack repairs 


Crack 

characteristics 

Sealing Filling 

Crack width 1/4" to 3/4" (5 to 19 mm) 1/4" to 1" (5 to 25 mm) 

Edge deterioration 

Minimal to none 

Moderate to none 

(spalls, secondary cracks) (equal to or less than 25% (equal to or less than 50% 

of crack length) 

of crack length) 

Annual horizontal 

movement 

equal to or less than 1/8" (3 mm) less than 1/8" (3 mm) 

• Transverse thermal 

• Longitudinal reflective 

Type of crack 

• Transverse reflective 

• Diagonal 

• Longitudinal cold joint 

• Longitudinal edge 

• Working longitudinal 

• Distantly spaced block 

Preparation 

• Routing/sawing 

• Cleaning/drying 

• Backer rod (if required) 

• Blowing out debris 

Materials 

Various materials can be used to repair cracks. There are many different desirable characteristics. 

All crack repair materials need to have good adhesion to the sides of the crack. Installation and 

performance issues are also factors that need to be examined. Table 7 shows the desirable 

properties of the various materials. Appendix A summarizes the most commonly used cracktreatment 

materials and provides recommendations for use, as well as basic cost information. 

As a general rule, materials that are more flexible will perform better in sealing operations. 

Polymer and rubberized materials have shown the best performance. 

Configuration 

Crack repair material is placed in a specific configuration that is most suitable for the 

application. Three basic configurations are shown in Figure 19. There are many other specialized 

configurations, but they are all variants or combinations of the three shown. 

Flush-Fill Overband Reservoir 

Figure 19 - Basic crack repair configurations 



Flush-fill 

The easiest and most common technique is the flush-fill. The material is placed into the crack. 

Excess material is then removed or blotted up. It is an easy repair, but edge deterioration can 

result in premature failure. The crack must be clean and dry prior to the repair. 

Overband 

Overbanding places material into and over an uncut crack. This technique is better than a flushfill 

at dealing with small deterioration, but the overband must be kept narrow. As a general rule, 

no overband should be wider than four inches. The material is slippery when wet and can result 

in a safety hazard. Multiple cracks filled in this way can lead to a patched area of crack sealant as 

shown in Figure 20. 

Reservoir 

In the reservoir technique, a saw or router is used to prepare a place to insert the repair material. 

This is more commonly done with sealing repairs. It increases the costs, but it may be necessary 

in order to provide sufficient working room for the sealant. 

Figure 20 - Crack sealing creating a safety hazard 

Limitations 

Crack repairs do not restore the structural integrity of the pavement. They can improve the 

strength of the pavement during wet periods, such as spring thaw, by eliminating or reducing the 

inflow of water under the pavement. 

Cracks should be sealed when they are at the middle of their working range. This allows the 

cracks to expand and contract with less stress on the sealant. A sunny day in spring or fall is a 

very good time to seal cracks, if all of the other weather factors are favorable. 


Table 7 – Properties of crack filling materials 

Material type 

Selfleveling 

silicone 

Lowmodulus 

rubberized 

asphalt 

Rubberized 

asphalt 

Asphalt 

rubber 

Fiberized 

asphalt 

Asphalt 

cement 

Polymermodified 

emulsion 

Asphalt 

emulsion 

Property 

�� 

� 

� 

Short prep 

�� 

�� 

�� 

�� 

�� 

� 

� 

Easy to place 

� 

�� 

�� 

�� 

�� 

�� 

Short cure time 

� 

� 

� 

� 

� 

�� 

� 

�� 

Adhesion 

� 

�� 

� 

� 

Cohesiveness 

�� 

�� 

� 

� 

� 

Resistance to softening and 

flow in cured state 

�� 

�� 

� 

� 

� 

Flexibility 

�� 

� 

� 

� 

� 

Elasticity 

�� 

� 

� 

Resistance to aging and 

weathering 


� 

�� 

� 

Resistance to tracking and 

abrasion 

Sealing 

Sealing 

Sealing 

Sealing 

(filling) 

Filling 

Filling 

Filling 

(sealing) 

Filling 

Recommended 

application 

� = Applicable �� = Very applicable 



Cracks should be repaired as soon as possible. Waiting a year can lead to additional 

deterioration, which may render crack repairs ineffective. A crack repair program can reduce, but 

not eliminate, the chances of cracks deteriorating too much before the work can be performed. 

Cracks are a sign of a failure somewhere in the pavement. Crack repairs do not generally fix the 

associated problems. When performing crack repairs, thought should be given to what future 

treatments may be needed. 

Performance 

There are many factors that can influence the expected life of a crack repair. Proper selection of 

good repair candidates is critical. When repairs are done on the correct candidates, the repair can 

last several years. 

Crack filling is expected to last two to four years when using emulsions or asphalt filler 

materials. Use of sealing products in non-working cracks has been shown to last six to eight 

years. Crack sealing without any routing or sawing typically lasts from three to five years. 

Routing out the cracks increases the life by two years, for a total of five to seven years. 

Costs 

Sealant materials costs are provided in Appendix A. As expected, sealing materials cost 

significantly more than filling materials. The cost of the application varies significantly 

depending on the construction operation and the productivity. Prices per lineal foot of crack can 

range from $0.02/foot for simple filling with asphalt emulsion, to over a $1/foot for a routed 

crack sealed with rubberized sealant. 

Crack repairs can be bid out by the municipality. The New York State Office of General Services 

bids out crack repairs with an award available to all municipalities. The award can be found at 

their web site (www.ogs.state.ny.us) under Highway Bituminous Materials. 

Construction Operations 

Crack treatment operations consist of five steps. 

This does not include traffic control, which needs 

to be set up properly beforehand. Crack repair 

operations are generally slow-moving, but special 

considerations may be needed on high-speed 

roadways. All five steps may not always be 

needed, depending upon the specific material 

configuration and placement options. Each step 

is described below. 

Crack cutting (optional) 

If there is a need to produce a reservoir for the 

crack material, then sawing or routing is required. 

Routing has a higher production rate, but sawing 

produces more vertical faces and a more uniform 

reservoir. Figure 21 shows crack routing. 


Figure 21 – Crack routing

Cleaning & drying 

Because dust and water will adversely affect the 

adhesion of crack repair materials, this is one of 

the most important steps. 

Airblasting with a backpack unit or air compressor 

will remove dust, debris, and some loose asphalt 

concrete pieces, but is not effective at removing 

surface moisture. If a moisture and oil filter is not 

properly installed, airblasting can actually 

introduce contaminants to the face of the crack. 

This is especially problematic when sealing. 

An alternative is to use a heat lance (Figure 22). 

This device removes dust and surface moisture. 

The heat from the lance can also help improve the 

bond of the crack repair, if the material installation 

follows closely behind the lance. 

Other cleaning methods include sandblasting and 

wire brushing. Depending upon the surface 

conditions, these methods may improve the 

quality of the crack repair. 

Crack repairs should never be done in rainy 

weather. Even the best heat lance cannot deal with 

the excess moisture. 

Material installation 

The method of installation depends on the material 

to be placed. Emulsions can be applied with hand 

held pour pots. Distributor wands with hoses are 

often used to place material in the crack. Figure 23 

shows basic wand application of crack sealer. 

In most cases, the materials need to be heated. 

The temperatures can be as high as 425°F. Safety 

around, and with, the crack material is a primary 

concern. Crews must be trained to properly heat 

and place the material. 

Figure 22 – Heat lance 


Figure 23 – Basic wand application of 

crack sealer 



Material finishing (optional) 

Squeegees or special attachments on the end of the 

distributor wand can be used to strike off the 

excess material. Squeegees are typically molded 

into a "U" shape which helps control the width of 

the material. Figure 24 shows a squeegee in use. 

Even when the work is supposed to be a flush-fill 

configuration, some material may not get into the 

crack. To control this excess material, finishing 

needs to be done with a squeegee or by blotting. 

Finishing can also reduce waste by pushing excess 

material into unfilled portions of the crack. 

Figure 24 – Finishing a crack with a 

Blotting (optional) 

squeegee 

Blotting reduces tracking and soaks up excess material. 

Sand is typically used, but if necessary it can be done with absorbent paper on a stick. 

Crack treatment weather 

As long as the crack is dry, crack repairs can be done almost any time of year. Spring and fall 

are very good times to repair cracks. The following conditions are recommended: 

• Temperature above 40°F (for sealing working cracks, the temperature should be below 80°F) 

• Humidity less than 80 percent 

• No chance of rain 


7 - Patching 

_____________________________________________________________ 

Patching is the single most common pavement maintenance technique. As the repair area gets 

larger, some agencies refer to it as a box-out or an area repair. The goals and concerns for an area 

repair are the same as for patching. The difference is scale and economics. 

Reasons for Patching 

Patching fixes localized distress and may improve safety by reducing roughness. It is used to 

repair structurally deteriorated pavement. Patching can also reduce the rate of deterioration of 

nearby pavement and fix distressed areas prior to pavement overlays. There are three general 

types of patching: semi-permanent, spray, and demand. 

Semi-permanent patching is done in the summer to fix potholes, repair poor patches, and replace 

demand patches placed earlier in the year. It is also performed with utility cuts and culvert 

installations. These types of patches should have nearly the same strength as the surrounding 

area. Drainage repairs are generally performed at the same time. The base is replaced if 

necessary. If drainage and base repairs are not made, the original problem may reappear. 

Spray patching is done with specialized equipment. It can either be planned or demand driven. A 

spray patch vehicle can be used in almost any weather, but summer spray patching is generally 

more successful. 

Demand patching is an unplanned repair to fix potholes. It is performed in the winter or spring, 

in all kinds of weather. It is usually done with patch material taken out by dump truck. The 

choice of material greatly influences the success of the patch. 

Semi-permanent Patching 

Semi-permanent patching is essentially a small-scale hot-mix asphalt paving operation. Some of 

the same concerns about patching (weather, materials and construction) also apply to semipermanent 

patching. For more details on asphalt paving, see the Cornell Local Roads Program 

manual entitled Asphalt Paving Principles (see Appendix B). 

A recent Pennsylvania study found semi-permanent patching to be three times more cost 

effective than other patching techniques, when full life cycle costs were considered. The initial 

capital cost is high, but the overall success rate may justify it. The study found that the lesspermanent 

patches usually had to be repeated multiple times, which made them more costly in 

the long run. 



Construction of semi-permanent patches 

Mark the patch boundaries 

When determining the area to be patched, straight 

boundaries are better (see Fig. 25). These are easier to 

cut and compact. Cut at least 12 inches beyond any 

severe cracking. The width of the patch area should 

accommodate the compaction equipment. Be sure to 

cut into sound material adjacent to the patch. 

Cut the boundaries 

The boundaries should provide a vertical face. A saw 

is preferred, but a jackhammer can be used. If using a 

jackhammer, be sure to keep the blade vertical. 

Remove the old material 

Figure 25 – Cut boundaries 

Remove the old broken asphalt. Try not to damage the good material outside the cut 

boundary. For larger area repairs, a small milling machine may speed up the process. The 

material removed can be used in other pavement repairs. The depth of removal will 

depend upon the site. In some cases, all of the asphalt is removed. If a lower layer of 

material is intact, try to leave it in place. 

Clean and repair the foundation 

After the old asphalt layer is removed, inspect the base and its drainage. In many cases, 

replacing the base and drainage is already planned. There will never be an easier time to 

replace the base than while the surface is open. When replacing the base, do not dig all 

the way to the edge of the cut boundary. Settlement may result in a premature failure 

along the edge of the patch. 

Since a pothole is evidence of distress, it is usually a good idea to remove at least the top 

couple of inches of the base material. The new patch will then be slightly thicker than the 

surrounding asphalt concrete layer. This will provide a bit of insurance if the underlying 

problem is not resolved during the repair. 

Apply a tack coat 

A tack coat should be applied to the vertical faces of the old asphalt. The tack coat should 

be sprayed or brushed into place. It should never be poured, which will lead to puddling 

and possible bleeding. RS-2 asphalt emulsion can be used as the tack. 

In some cases, the bottom of the hole may need to have a tack coat applied. This is 

especially true when patching over asphalt or concrete base materials. If patching over 

gravel, a tack coat may be able to replace the prime coat that is normally used. It can be 

hard to justify using two different materials to help bond the various layers together. 


Cut Boundary 

Cut Boundary 

Poor 

Good

7 - Patching 

Fill the hole with patching material 

Place enough material in the hole to allow for compaction. As a general rule, one quarter 

inch of compaction will occur for every inch of material placed. If the patch is four 

inches thick, the material should be placed to one inch above the surrounding area. 

The material chosen will depend on the availability of hot-mix, and the number of 

patches being done. Doing several patches at once can be more efficient and allow for the 

purchase of full truck loads. For more information on the types of asphalt mixes 

available, refer to Asphalt Paving Principles (see Appendix B). 

Do not back the truck into the hole. This will damage the edge of the cut area. If the patch 

is very large, plywood can be layed down, to spread the load out and allow the truck to 

carefully back into the excavated area. Move the material around with a shovel. Dragging 

the asphalt with a rake can lead to segregation. 

Compact the patch 

Compaction can be done a variety of ways. 

A roller is best. Put down no more than six 

inches at one time. If the patch is deeper 

than six inches, use multiple lifts. 

A plate tamper may be used, but the 

compactive effort is much smaller and the 

required density may not be achieved. This 

can result in premature failure. When using 

a plate tamper, keep the lifts no more than Figure 26 – Finished patch 

three inches thick. 

A compacted patch should be flush with the surrounding surface. If properly compacted, 

the patch will not settle significantly and create a traffic hazard. Figure 26 shows a 

properly finished and compacted patch. 

Cleanup 

Clean up the site. Pick up any loose material, and police the area around the patch. This 

is primarily for safety. Loose material hit by passing vehicles could also expose a 

municipality to liability. This is good for public relations as well. 

Spray Patching 

Spray patching potholes is a very effective technique. It requires a specialized truck or trailermounted 

equipment. These units can be purchased or rented as needed. The quality of spray 

patch is very good. One advantage is that the equipment can be used in almost any weather. 

The equipment is self-contained. In some cases it can be done by the driver alone. The trailermounted 

patchers require a driver and an operator, but can sometimes reach patches more easily 

than the truck-mounted devices. In all cases, traffic control is critical to ensure safety. Figure 27 

shows an example of a self-contained spray patch truck. 



Spray patching involves the following steps. 

• Blow debris from the hole 

• Spray a tack coat of binder on the 

sides and bottom of the hole 

• Blow a mixture of aggregate and 

binder into the hole 

• Top off with a layer of uncoated 

aggregate, to blot the surface and 

prevent tracking 

Demand Patching (Cold patch) 

Demand patching is one of the most common pavement maintenance techniques. There is 

usually pressure to make repairs as quickly as possible. Some municipalities have a 24-hour 

standard for patching potholes. If the patch fails, the municipality still has a liability problem, 

and has to go back and refill the pothole. Demand patching restores safety, but does not repair 

the underlying distress. 

Materials 

Demand patching materials generally come in three different forms: 

• Standard cold patch or plant mix 

• Fiber reinforced patch material 

• Modified cold patch (proprietary) 

Materials can be prepared ahead of time and placed into stockpiles or even packed in buckets or 

bags. Bags of patching mix can be kept in the back of a pickup for emergency repairs. The extra 

weight can also help improve the vehicles traction in the winter. 

The optimum material is made with high quality aggregate. The binder needs to contain antistripping 

agents. These agents deal with the water found in many potholes which are filled in the 

winter and spring. The material needs to be workable at low temperatures, but still have stability 

under traffic. 

This unique combination of properties makes cold patch material difficult to manufacture. Less 

expensive mixes tend to either strip or have no stability under traffic. They cannot handle the 

traffic load placed upon them, and they fail very quickly. 

The first major improvement to cold patch was the addition of fibers. This improved the stability, 

but also increased the price. More recently, proprietary mixes with specially formulated binders 

have been produced. These materials can be twice as expensive as standard mixes, but may be 

more cost effective, due to a higher success rate. 

Proprietary mixes are bid out by the New York State Office of General Services (OGS). New 

products are being developed all the time, so a comprehensive list of materials cannot be easily 

produced. Table 8 lists the proprietary cold patch products bid out in 2005 via OGS. 


Figure 27 – Self-contained spray patch truck

Table 8 - Proprietary cold patches on NYS OGS bids, 2005 

Patch name Producer or manufacturer 

BOND X Seaboard Asphalt Products, Inc. 

DURO PATCH Gorman Bros. 

HYPERPATCH Vestal Asphalt, Inc. 

I.A.R. I.M.U.S., Inc. 

MAC-V Midland Asphalt Corp. 

MC-400P Koch Materials Co. 

NORJOHN SPC Norjohn Ltd. 

OPTIMIX Optimix, Inc. 

PARCO PATCH Peckham Materials Corp. 

PERFORMIX Seaboard Asphalt Products 

QPR QPR, A Division Of Lafarge N.A. 

S-K MOD Suit-Kote Corp. 

SYLCRETE EV Sylcrete Corp. 

TOP MIX Tech Mix 

UPM Unique Paving Materials 

7 - Patching 

There are differences between the various proprietary cold patch materials. Some work better in 

cold weather, some are easier to finish, some are more forgiving under traffic. When choosing 

which material to use, price is not usually a significant factor. All of the proprietary materials are 

similar in price. The one you should use is the one which will work properly in your conditions. 

Repair technique 

Cold patch should be compacted with a roller or a plate tamper, but in practice it is rarely done. 

Speed of repair is the primary reason for this, which has earned the technique the name “Throw 

and Go.” The problem with Throw and Go is that the lack of compaction causes the material to 

fail very quickly. Patches placed one day are often gone the next. 

A more effective technique is “Throw and Roll.” The only difference is that the truck is used to 

compact the mix. Truck tires do a fairly good job of compacting the mix. With compaction, more 

patches will survive the season. The steps of Throw and Roll are listed on the next page. 

The production speed of Throw and Roll is not much less than Throw and Go. Rolling over the 

patch typically increases the survival rate (the number of patches that will survive the season) 

from 10 to 25 percent . Using a proprietary mix, as opposed to a standard cold patch, can double 

the survival rate to 50 percent. 



“Throw and Roll” steps 

1. Place the material into a pothole 

(remove as much water and/or debris 

as possible from the hole beforehand). 

2. Compact the patch using truck tires, 

as shown in figure 28. 

3. Verify that the compacted patch has 

some crown (1/4 inch above the 

surrounding pavement). 

4. Move on to the next pothole. 

Cost effectiveness 

Table 9 illustrates the effect of rolling the patch, and using modified mixes. Typically reported 

survival rates are given for each technique. The price is the average from the NYS OGS. The 

calculations are for 20 tons of cold patch. The productivity is 20 tons per day for Throw and Go 

and 15 tons per day for Throw and Roll. 

The total cost assumes that the failed potholes have to be refilled up to three times. Even with the 

higher initial cost and slower production rate, Throw and Roll is more cost effective. The higher 

survival rate of a proprietary mix can justify the extra initial expense. 

Table 9 - Cost effectiveness of various demand patching methods 

Method 

Throw & Go 

(standard 

cold patch) 

Throw and Roll 

(standard cold 

patch) 


Figure 28 – 'Rolling' a cold mix patch 

Throw & Roll 

(proprietary 

cold patch) 

Price ($/ton) $45/ton $45/ton $72/ton 

Materials $900 $900 $1,440 

Labor $676 $901 $901 

Equipment $200 $267 $267 

Initial cost $1,776 $2,068 $2,608 

Survival rate 10% 25% 50% 

Total cost $4,813 $4,782 $4,564

8 - Thin Wearing Courses 

_____________________________________________________________ 

Chip seals, slurry seals, surface treatments, 

micropaving, and thin overlays all fall under the 

category of thin wearing courses. They all have 

some common characteristics and are used in 

similar places. Figure 29 shows a chip seal in 

progress. 

Purpose of Thin Wearing Courses 

There are some critical differences between the 

various surfacing techniques, but they all do the 

following: 

• Seal and protect the layers below Figure 29 – Spreading stone for chip seal 

• Provide a skid resistant surface 

• Seal oxidized surfaces 

Thin wearing courses are considered preventive maintenance, and are not expected to provide 

structural support to a pavement. They are used to seal very fine cracks and to waterproof the 

pavement. They can also improve skid resistance and restore a weathered, oxidized surface. 

Some specific wearing courses, micropaving and Novachip®, can fill minor ruts up to 3/4 inch. 

The effective use of thin wearing courses relies on their application before any serious pavement 

deterioration has occurred. Timing of application is therefore critical. One of the myths about 

thin wearing courses, and chip seals in particular, is that they are not engineered, and are more 

art than science. There is plenty of science and engineering behind the proper selection and 

placement. 

Types of Thin Wearing Courses 

The most common thin wearing courses are listed in Table 10, which also shows the basic 

distresses they repair. Not mentioned in the table are fog seals, cape seals, double chip seals and 

sandwich seals. These are used less frequently, and thus will not be discussed here 



Table 10 - Distresses repaired by selected thin wearing courses 

Waterproofs 

the pavement 

Restores skid 

resistance 


Restores an 

oxidized surface 

Trues & levels 

minor ruts 

Sand seal Yes Yes Yes No 

Chip seal Yes Yes Yes No 

Slurry seal Yes Yes Yes No 

Micropaving Yes Yes Yes Up to 3/4" 

NovaChip Yes Yes Yes Up to 1/2" 

Thin overlay Yes Yes Yes No 

Overlays (up to one inch thick) are a type of thin wearing course. Until almost one and a half 

inches are placed, there is not a significant strength increase provided by the asphalt concrete 

overlay. A thin overlay will not correct minor ruts. Unless a separate true and leveling course is 

applied first, traffic will recompact a single lift of asphalt back in the existing ruts. Micropaving 

and Novachip, on the other hand, were designed to fill minor ruts. 

Sand seal 

A sand seal is a layer of asphalt emulsion covered by a layer of fine aggregate (sand). It is not as 

durable as a chip seal. Sand seal has an expected lifespan of four to five years, if placed at the 

right time, and in the right place. 

Chip seal 

Also known as a surface treatment, a chip seal is a 

layer of asphalt emulsion covered by a layer of 

single-sized aggregate. Timing of the construction, 

and the weather during construction, have major 

influences upon the success or failure of a chip 

seal. Chip seals will be discussed in more detail 

later in this chapter. Figure 30 shows the proper 

spacing between the laying of the emulsion and the 

chip spreader during a chip sealing operation. 

Figure 30 – Proper spacing of 

emulsion and chip spreader

Slurry seal 

A slurry seal is a mixture of fine 

aggregate, mineral filler, slow 

setting asphalt emulsion, and water. 

A specialized piece of equipment 

combines the ingredients, places the 

mixture in a spreader box, then lays 

the material onto the pavement 

surface. Portland cement and other 

additives are used to control the 

setting time. This allows traffic on 

the slurry sooner. Figure 31 shows a 

slurry seal equipment schematic. 

Slurry seals come in three different 

grades, based upon the largest aggregate. 

Sizes range from 1/8 to 3/8 inches. Table 11 

lists the aggregate gradations used for slurry seals. 


Asphalt content will vary from 6.5 to 16 percent, depending on the application. Aggregate 

gradations are tightly controlled to ensure proper mixing. One disadvantage of slurry seals is the 

long curing time needed until traffic can use the road, up to two hours after construction. Use of 

quick-set slurries will improve the setting time. 

Table 11 - Aggregate gradations used for slurry seals (ISSA 1998) 

Sieve size 

Type I 

gradation 

Percent passing 

Type II 

gradation 

Type III 

gradation 

3/8" (9.5 mm) 100 100 100 

#4 (4.75 mm) 100 90-100 70-90 

#8 (2.36 mm) 90-100 65-90 45-70 

#16 (1.18 mm) 65-90 45-70 28-50 

#30 (0.60 mm) 40-65 30-50 19-34 

#50 (0.33 mm) 25-42 18-30 12-25 

#100 (0.15 mm) 15-30 10-21 7-18 

#200 (0.075 mm) 10-20 5-15 5-15 

Cornell Local Roads Program 49 

1 

2 

3 

4 

5 

6 

7 

1 

2 

3 

5 

6 

7 

8 

Figure 31 – Slurry seal 

equipment schematic 

4 

9 

Aggregate Bin 

Filler Bin 

Aggregate Flow Gate 

Aggregate Conveyor Belt 

Emulsion Injector 

Water Injector 

Pugmill 

Spreader Box 

Slurry 

9 8


Micropaving 

Micropaving, also called microsurfacing, is a 

slurry seal with the addition of a polymermodified 

asphalt emulsion (see Fig. 32). 

Micropaving can fill minor ruts up to 3/4 inches 

deep in a single pass. The polymer and other 

additives allow for rut filling and reduce the time 

until traffic can resume. The polymer is usually 

rubber latex. Other rubber type compounds are 

also used. 

Micropaving comes in two different grades, based 

upon the largest aggregate. There are two 

aggregate gradations available: Type 2 (1/4 inch) 

and Type 3 (3/8 inch). 

Microsurfacing overlays are applied in two 

passes. The first pass, often called the scratch 

course, evens out surface irregularities such as 

wheelpath rutting, and prepares the pavement for 

the surface course. The second course provides a 

smooth wearing surface. No compaction is 

required, but the emulsion must cure before 

traffic is allowed on the surface. Traffic can 

usually resume in less than one hour after 

application. 

Aggregate Bin 

Mineral Filter Bin 

Additive Storage 

Metered Aggregate 

Microsurfacing will seal the pavement, thereby reducing oxidation and weathering of the old 

surface. Less oxidation keeps the pavement resilient to fatigue and low temperature cracking. 

Minor surface distresses such as ravelling may also be prevented or corrected. The final 

thickness of microsurfacing is approximately 1/2 inch (12 mm) to 7/8 inch (20 mm). 

NovaChip 

NovaChip (referred to as paver placed surface treatment in NYSDOT specifications), was 

developed in Europe and introduced in the United States in 1992. Paver placed surface treatment 

consists of a warm polymer modified asphalt emulsion coat, followed immediately with a thin 

hot mix asphalt (HMA) wearing course. A self-priming paver applies the warm emulsion coat 

directly in front of the paving screed. Three gradations are available for the HMA wearing 

course: Types A, B or C. The nominal maximum aggregate sizes are 1/4 inch, 3/8 inch, and 1/2 

inch for Types A, B, and C, respectively. The HMA overlay is placed from one to one and a half 

aggregate particles thick. 

Like Micropaving, NovaChip will seal the pavement, reducing oxidation and weathering of the 

surface. Surface distresses such as raveling and moderate rutting may also be corrected. 


Metered Micro-Surfacing Emulsion 

Metered Water & Additive 

Pugmill 

Micro-Surfacing 

Surfacing Spreader Box 

Brown to Black Color 

Road Water Spraybar 

Figure 32 – Micropaving 

equipment schematic


Gradations available for HMA wearing course: 

• Type A is the finest gradation and is considered the lightest duty mix. Its fine surface 

texture is excellent for urban and suburban applications, with some light truck traffic. 

It will also reduce the noise. Due to its fine surface texture, it should not be used for 

high speed traffic. Type A is not recommended for highways which are borderline 

candidates for preventive maintenance. A coarser gradation should be used in those 

cases. 

• Type B is the middle gradation. It is durable enough to handle moderate to heavy 

truck traffic on highways with moderate speeds. Type B can also be used in lighter 

duty applications, if a slightly thicker lift is desired, or if more surface distress is 

present. 

• Type C is the coarsest gradation and heaviest duty mix. Type C can be used for any 

application, regardless of traffic levels. This mix is recommended for high speed and 

high traffic applications, and for applications with moderate rutting. This type may be 

noisier under traffic. 

Thin overlay 

A thin overlay is placed with conventional paving equipment, and is generally less than one inch 

thick. Just like other thin wearing courses, it provides a new surface and waterproofs the 

pavement. Reflective cracks will come up through the overlay in one to two years. Crack sealing 

the year before application can reduce this problem. 

A 1/4 inch (6 mm) mix is a very thin hot mix asphalt (HMA), using the Superpave mix design 

procedure. It consists of a high quality aggregate mixture and a PG 64-28 binder, modified to 

meet an elastic recovery requirement. Just like a standard hot mix, a tack coat is strongly 

recommended, to bind the thin lift mix to the surface. The tack coat used is diluted asphalt 

emulsion (see Table 13). 

Materials for thin wearing courses 

Except for hot mix asphalt used in thin lift asphalt concrete mixes and Novachip, all thin wearing 

courses have two materials in common: asphalt emulsions and aggregate. The characteristics of 

both are critical to the success of most thin wearing courses. 

Aggregate 

Aggregate is just a fancy term for stone and sand. Coarse aggregate is stone, fine aggregate is 

sand. Using a NYSDOT approved material is always recommended. Aggregate approved by 

NYSDOT has been tested to ensure that it meets minimum standards. For wearing courses, the 

following characteristics are important: 

Cleanliness 

Aggregates containing foreign matter (vegetation, shale, soft particles, clay coatings, or clay 

lumps) are unsatisfactory. For use in wearing courses, no more than one percent fines should 

be allowed. Any more than that and the asphalt emulsion will be bound up by the fines rather 

than acting as a binder for the larger aggregate. 



Toughness 

The aggregate particles are the actual driving surface of a roadway. They must be able to 

resist wear and crushing. A good quality aggregate can handle all kinds of traffic without 

breaking apart. 

Soundness 

In New York State, all surface aggregates must be able to handle freezing and thawing 

without breaking down into smaller particles. Shale, for instance, should not be used as a 

surface material. Shale breaks down into much smaller particles as it freezes and thaws. The 

'soundness test' uses a solution of magnesium sulfate. The aggregate sample is put through a 

number of soaking/drying cycles. The percent loss by weight of each size fraction of material 

is determined and used as a measure of soundness. Aggregates for wearing courses are 

subjected to a more severe soundness test than aggregates for subbase courses. 

Particle shape 

Crushed, cubical stone is best for wearing courses. Crushed faces help improve both friction 

for traffic and stone interlock. Cubical stones perform better and last longer in surface 

treatments. 

Polishing 

Some limestones and dolomites have a tendency to polish under traffic wear. This reduces 

friction and creates a safety hazard. Wearing course aggregates must not be prone to 

polishing. High friction aggregates are usually specified. 

Absorption 

A small amount of absorption is desirable in asphalt mixes. This allows the aggregate to 

absorb some asphalt, forming a link between the asphalt film and the aggregate. Highly 

porous aggregate is not desirable, it absorbs too much asphalt. Burnt slag and other synthetic 

aggregates are highly absorptive, but they have a rough surface texture which makes them 

attractive for use in asphalt mixes. 

Particle Sizes 

Table 12 shows the sieve sizes for the most common aggregates used in chip seals. 1ST stone 

has a tighter gradation band and is preferred over 1A or 1. 

Table 12 - Sieve sizes for common chip seal aggregates 

(NYSDOT Standard Specifications, Section 703-02, English units) 

Size 

Sieve Size (percent passing) 

Designation 1 inch 1/2 inch 1/4 inch 1/8 inch #200 sieve 

1A - 100 90-100 0-15 0-1.0 

1ST - 100 0-15 - 0-1.0 

1 100 90-100 0-15 - 0-1.0 



Emulsified asphalts 

Asphalt emulsions are a mixture of asphalt cement, water, and an emulsifier (similar to a soap or 

a detergent). Some emulsions have a small amount of petroleum distillate (naptha) added to 

promote the coating of the aggregate. The emulsion is produced by milling the hot asphalt 

cement into minute globules, then dispersing it in water treated with a small quantity of 

emulsifying agent. Between 55 and 65 percent of the final emulsion is asphalt, with the balance 

being water (see Table 13). 

Depending on the agent, the emulsion may be anionic (with negatively-charged asphalt particles) 

or cationic (with positively-charged asphalt particles). Emulsions are made in several grades, as 

shown in Table 13. Most emulsions can be modified with polymers to improve performance or to 

meet special needs. 

Table 13 - Asphalt emulsions and residual asphalt content 

(NYSDOT Standard Specifications, Section 702) 

Anionic Cationic Typical use 

RS-1 55% CRS-1 60% Spray patching 

RS-2 63% CRS-2 65% Surface treatment 

HFRS-2 63% - - Surface treatment 

MS-2 65% CMS-2 65% Cold mix, base stabilization 

- - CMS-2h 65% Cold mix, base stabilization 

HFMS-2 65% - - Cold mix, base stabilization 

HFMS-2h 65% - - Cold mix, base stabilization, 

tack coat (diluted) 

HFMS-2s 65% - - Stockpile patch 

SS-1 57% CSS-1 57% Base stabilization 

SS-1h 57% CSS-1h 57% Base stabilization, tack coat 

(diluted) 

The RS, MS or SS indicates the setting rate of the emulsion: RS = rapid set, MS = medium set 

and SS = slow set. The 'h' means that a hard asphalt was used. The 's' means a soft asphalt was 

used. The 'HF' designates a high-float emulsion. High-float emulsions have certain chemicals 

added, to allow thicker asphalt films on the aggregate particles with minimal drain-down. The 

number '1' or '2' relates to the viscosity. A '1' is more fluid and better for penetration and 

patching, while a '2' is more viscous and better for thin wearing courses. 



For use in thin wearing courses, asphalt emulsions are modified to optimize viscosity, coating 

properties, and break time. As long as the emulsion remains in droplets, the fluid will coat stones 

and allow their placement. The right asphalt emulsion will: 

• Be fluid enough to spray properly 

• Retain the proper consistency to wet the applied aggregate 

• Cure and develop adhesion quickly 

• Hold the aggregate tightly 

• Not bleed or strip with changing weather conditions 

Breaking of emulsions 

After a period of time, the emulsion “breaks.” This is the recombining of the asphalt droplets 

back into a continuous mass as the water evaporates. Once this occurs, additional stone cannot 

bind to the emulsion, and the chances of stripping are much greater. Once it has broken, the 

emulsion will change from a dark brown to black. 

Curing of emulsions 

After emulsions are applied to aggregate, they go through a curing period in which the water 

evaporates from the emulsion. This leaves the asphalt film on the aggregate for cementing and 

waterproofing. 

Breaking time 

The breaking time for an emulsion is controlled by the formulation of the emulsifier. Rapidsetting 

emulsions are designed to break quickly after contact with the road, and the cover 

aggregate for a chip seal must be applied within one to two minutes. On a dry, sunny day, the 

breaking time may be less than one minute. 

Curing time 

Curing is the evaporation and removal of the water and any solvents from the emulsion. Total 

curing can take from 7 to 14 days, depending on the mix type, emulsion used, aggregate type, 

and environmental conditions. The evaporation rate is one of the most critical factors in how 

long curing will take. 

The evaporation rate is affected by temperature, humidity, wind speed, cloud cover, and shade. 

Humidity has a major influence on the evaporation rate of an asphalt emulsion. At 60°F and 60 

percent humidity, evaporation is faster than at 100°F and 80 percent humidity. As the fall season 

begins, nighttime cooling can almost completely stop evaporation. Construction in the middle of 

the summer is preferred with all thin wearing courses, in order for the emulsions to cure quickly. 


Chip seals 

Chip seals are the most common thin wearing course. 

Many of their details are applicable for all other wearing 

courses. 

This section is not intended to cover everything about chip 

seals, it is merely a guide to help explain the process and 

the most critical factors involved. Additional training and 

experience is needed for someone to become an expert. If 

you are interested in training your crew, check with a local 

vendor. They may be glad to help. 

In a chip seal, an asphalt emulsion is sprayed on a cleaned 

road surface, and immediately spread with a layer of 

single-sized stones. The stones are then rolled. This 

orients and seats them within the emulsion layer. Figure 

33 illustrates these steps. A few days later the surface is 

lightly broomed to remove any loose aggregate. 

Rolling 

Spreading 

Spraying 


Existing surface 

Materials 


Chip seals typically use rapid-set asphalt emulsions (RS-2, 

CRS-2, and HFRS-2). Some agencies have used medium set 

emulsions, but the longer break and curing times are more Figure 33 – Chip seal placement 

prone to failure. Polymer modified emulsions have been used 

on higher volume roadways. These emulsions cost more, but 

have increased adhesion and may last longer. 

The aggregate should be a very clean, durable, single sized stone. In New York State, 1ST and 

1A stone are most commonly used. The 1st gradation was specifically formulated for use in 

surface treatments (chip seals). The aggregate should be cubical. Flat particles tend to get rolled 

onto the flat side, and are more likely to be covered by the emulsion layer. 

The goal is to embed the aggregate around 70 percent deep into the residual asphalt. Less than 50 

percent embedment tends to result in a loss of stone (raveling). More than 80 percent tends to 

result in excess asphalt on the surface (bleeding). 

Application rates 

The finished chip seal should have one layer of stone embedded 60 to 80 percent into the asphalt 

binder, with 70 percent being optimum. To determine the amount of asphalt needed to acomplish 

this, we need to determine the volume of the voids in the stone. When determining the amount of 

emulsion to apply, there are two different numbers to calculate. 



Residual Asphalt 

The first number to calculate is the amount of asphalt that will remain after curing. This is the 

residual asphalt. The other number is the emulsion spread rate, in gallons per square yard or liters 

per square meter. Figure 34 illustrates the process. The emulsion is a mixture when it is first 

sprayed. After it breaks, the water and asphalt separate. The water gradually evaporates, and the 

asphalt remains. It is this residual asphalt into which the stone needs to be 70 percent embedded. 

In RS-2, the asphalt in the emulsion is 63 percent (see Table 13). The other 37 percent is mostly 

water. This will cure out (evaporate). To obtain the emulsion spread rate, divide the residual 

asphalt amount by the percentage of asphalt in the emulsion. If the residual asphalt rate is 0.30 

gallons per square yard, then the emulsion spread rate is 0.45 (0.30 ÷ 63%). 

As shown in Table 13, the residual asphalt content is not the same for all types of emulsions. 

Be sure to use the correct percentage in your calculations. 

emulsion 

water 

residual 

asphalt 

Spray Break Cured 

Figure 34 – Residual asphalt 


water 

(evaporated) 

residual 

asphalt 

Void calculation 

After compaction, the void space between the stones is reduced to around 20 percent of the total 

stone volume. We want about 70 percent of this void space to be filled with asphalt. The amount 

of asphalt needed can be calculated from the average stone size (see Figure 35). 

This is a complicated process requiring knowledge of the aggregate gradation, bulk density, and 

specific gravity, with a correction for aggregate particle shape. Fortunately, there is a much 

easier process, involving the board spread rate.

Residual 

asphalt 

Aggregate 



ALD 

Figure 35 – Average Least Dimension of chip seal after curing 

Board spread 

This method provides the aggregate spread rate directly, and it gives a good estimate of the 

emulsion spread rate. To determine the board spread rate, take a one-square-yard board, and 

cover it with the actual stones to be used. Spread the stones until they cover the board only one 

stone deep. Weigh this material. This amount of stone, in pounds, is the board spread value in 

pounds per square yard. 

The emulsion rate in, gallons per square yard, is the board spread value divided by the 

percentage of asphalt in the emulsion. For a 1ST stone with an RS-2 emulsion, a typical board 

spread value might be around 25 pounds per square yard. The emulsion rate would then be: 

Emulsion application rate = 25 lbs/yd 2 ÷ 63 = 0.40 gallons/yd 2 

The results from the two methods of calculation are very close to each other. This gives a starting 

point for discussion with the vendor. 

The actual stone spread rate is usually slightly higher than the amount determined by a single 

stone layer. The difference is called “whip off”, and is approximately 5 percent. It accounts for 

the loss of stone due to traffic. Do not add more stone than necessary. This can lead to the 

dislodging of stones from the surface, which contributes to bleeding. 

There are more precise methods for determining emulsion application rates. This method allows 

a simple and quick check of the values provided by the vendor. If you are not sure about the rate, 

ask the vendor to explain it. 

Adjustments 

The condition of the road surface before the chip seal is placed, and the traffic level of the road, 

may necessitate adjustments. A smooth, dense surface will absorb less asphalt than an open, 

porous one. An increase in traffic will reduce the need for asphalt emulsion, due to the increased 

embedment of the aggregate which results. 

Although adjustments are sometimes needed, even small changes can lead to problems. A 

change of only 0.04 gallons/yd 2 in the wrong direction could result in not enough embedment, or 

in bleeding. Be sure everyone agrees on any adjustments to the application rate before starting 

the work. Table 14 lists some emulsion application rate adjustments. 



Table 14 - Emulsion application rate adjustments 

Surface texture 


Adjustment (in 

Gallons/s.y.) 

Black, flushed asphalt - 0.01 to -0.06 

Smooth, nonporous none 

Absorbent - slightly porous, 

oxidized 

+0.03 

Absorbent - slightly pocked, 

porous, oxidized 

+0.06 

Absorbent - badly pocked, 

porous, oxidized 

+0.09 

Average daily traffic (vehicles per day) Adjustment 

Under 100 +15% 

100-500 +5% 

500-1000 None 

1000-2000 -5% 

Over 2000 -10% 

Surface preparation 

Crack repairs and patching should be done at least three months ahead of chip sealing. 

Depressions, ruts, and bumps should be filled. Due to the short construction season, it is better to 

do such work the previous year if possible. Even with a rubber-tired roller, a smooth road is 

easier to surface-treat. The smoother the surface, the better the resulting chip seal. 

A day before the chip seal is to be done, the surface should be broomed. This can be done several 

days in advance if necessary. It is better to do it early than not at all. 

Equipment preparation and calibration 

The equipment needs to be prepared and calibrated before use. All the mechanical parts need to 

be checked. The aggregate spreader (Figure 36), or the chipper boxes, definitely need to be 

checked to make sure they are working properly, the chutes are open, and the correct aggregate 

spread rate is being applied. 

The distributor nozzles must be correctly aligned (Figure 37), and the spray-bar height set 

properly for complete overlap (Figure 38). A triple lap is usually recommended. If either is set up 

incorrectly, streaking will occur. 

Prior to application on the road, the chipper and the distributor should be calibrated. The 

calibration test will also allow a check of the working operation of all of the equipment. To 

calibrate the stone rate, place a one-square-yard canvas panel on the ground. Have the chipper 

spread stone across the panel (it may be necessary to anchor the panel). Weigh the stones on the 

panel. The amount of stone should closely match the figure calculated for the application rate. If 

chipper boxes are being used, each box needs to be calibrated separately.

Single lap 

Double lap 

Triple lap 

Figure 36 - Self-propelled aggregate spreader 

CORRECT - Nozzles at same angle 

INCORRECT - Nozzles at different angles 

Figure 37 - Spray bar alignment 

Nozzles . 

Spray Bar 

Road Surface 

Figure 38 - Spray lap coverage 


15-30° 

Variable 

angle 



To calibrate the distributor, take a one-square-yard piece of plastic or a wooden panel, weigh it, 

then place it on the ground and have the distributor drive over it at normal speed, spraying 

emulsion. Weigh the panel again. Subtract the original weight. To convert from pounds to 

gallons, multiply the weight in pounds by 0.12. If the emulsion weighs 3.3 pounds, this equals a 

spread rate of 0.40 gallons per square yard. 

Alternatively, make a note of the gauge setting on the spray vehicle, have the distributor shoot a 

measured area, then read off the amount of material placed. This assumes the gauge is working 

correctly. At the end of the construction day, check the weight tickets versus the area treated. 

They will not match exactly, but the amount on the tickets should be close to the figure of the 

area times the application rate. 

The stones need to be rolled at least once in the first minute after they are spread. The rollers 

need to be checked to make sure they are working properly and that the tires are properly filled. 

Decide beforehand how many rollers you will need. It is much better to have too many rollers 

than too few. You will need at least two rollers to compact a single lane in one pass. 

Construction 

Construction is a five-step process. Each step is important for different reasons. 

Sweep 

Sweeping dust or materials off the road will help 

the chip seal bond to the surface. Sweeping can be 

done before the day of the chip seal operation, but 

keep a broom on hand to clean up as needed. 

Spray the emulsion 

The distributor should place the emulsion just in 

front of the aggregate spreader. No more than 30 

seconds should elapse between the spraying of the 

emulsion and the spreading of the aggregate. 

In Figure 39, there is too much distance between 

the distributor and the spreader. By the time the 

spreader lays down the aggregate, the emulsion 

will have broken and the stone will not adhere 

properly. 

Spread the aggregate 

The aggregate should be placed quickly and efficiently. Self-propelled spreaders are more 

consistent than spreader boxes, and usually compensate for their extra expense in increased 

productivity alone. On a two-lane road it is customary to leave a few inches of emulsion 

along the centerline uncovered with stone when constructing the first lane. Then, when the 

second lane is constructed, the distributor should shoot the overlap area, and the spreader 

should lay stones over this zone. This assures that a double layer of chip seal will NOT be 

built along the centerline. A double layer at that location can be difficult for vehicles to drive 

over safely. 


Figure 39 – Improper spacing of 

emulsion and chip spreader


Roll the aggregate 

Rolling is usually done with a rubber-tired roller. The first roller pass should be able to cover 

all of the chips at least once within a minute of laydown. If this is not possible, get more 

rollers. The entire surface should be rolled at least twice before leaving for the day. Overrolling 

is just about impossible. 

The haul trucks can help the compaction by staggering their wheel tracks. They should 

approach the spreader by backing over the freshly laid and compacted chip seal. The trucks 

should go very slowly and avoid any sharp turns or sudden stops. 

Sweep 

The final step is to sweep up any loose aggregate. This should be done a day or two after the 

chip seal is placed. Waiting longer will not help embed any more stones. The sweeper must 

use very little down-pressure. The objective is to remove the already-loose stones, not to 

loosen additional material. 

Chip seal failures 

The average life of a chip seal in the U.S. is just under six years (5.76). There are many examples 

of chip seals lasting for 10 or more years. They fail prematurely for a variety of reasons. A recent 

survey of state and local highway departments found the most common reasons for chip seal 

failures: 

• Sealing in the wrong weather 

• An improper emulsion application rate 

• An improper aggregate application rate 

• Placing the aggregate too late, after the emulsion has broken. 

Each of these problems can be avoided with a little training and planning. 

Thin wearing course placement weather 

The closer to the middle of summer, the more likely it is that the surface treatment will 

succeed. Surface treatments should be placed between Memorial Day and Labor Day in 

most of New York State. The following weather conditions are preferred. 

• Air temperature above 50°F ( The temperature at night should not go below 45°F) 

• Pavement surface temperature above 70°F and below 130°F 

• Humidity below 75 percent 

• No chance of rain 

• Not too windy, but some wind may help the curing of the asphalt emulsion 

Thin wearing courses generally cost more per mile of road than other pavement maintenance 

techniques. Their greater cost will be warranted when it is the proper treatment, put down 

correctly, at the right time. 


APPENDIX A - CRACK TREATMENT MATERIALS 

2006 Cost range, 

$/lb 

Recommended 

application 

Crack filling 0.13 to 0.21 

Applicable 

specifications 

ASTM D 977 & AASHTO M 140, 

ASTM D 2397 & AASHTO M 208 

Example 

products 

CRS-2, CMS-2, 

HFMS-1 

0.53 to 0.78 

Crack filling 

(possibly sealing) 

ASTM D 977 & AASHTO M 140, 


Elf CRS-2P, 

Hy-Grade Kold Flo 


ASTM D 3381, AASHTO M 20, 

AASHTO M 226 

AC-10, 

AC-20 

— Various state specifications Crack filling 0.21 to 0.36 


Crack sealing 

(possibly filling) 

Manufacturer’s recommended 


Various state specifications, 

ASTM D 5078 


& Fed SS-S-164 

Material 

type 

Asphalt 

emulsion 

Polymermodified 

emulsion 

Asphalt 

cement 

Mineral-filled 

asphalt cement 

Fiberized 

asphalt 

Asphalt 

rubber 

Rubberized 

asphalt 

Rubberized 

asphalt 

Low-modulus 

rubberized 

asphalt 

Self-leveling 

silicone 

0.31 to 0.43 

Crack sealing 0.36 to 0.57 



& Fed SS-S-1401 


Various state modified 

ASTM D 3405 specifications 


Manufacturer’s recommended 


Hercules FiberPave ® +AC, 

Kapejo BoniFibers ® +AC 

Koch 9000, 

Crafco AR2 

Meadows #164, Koch 9001, 

Crafco RS ® 211 

Meadows Hi-Spec®, 

Koch 9005, Crafco RS®221 

Meadows XLM, Koch 

9030, 

Crafco RS ® 231 

Dow Corning ® 890-SL, 

Crafco 903-SL 

Cornell Local Roads Program 63 


APPENDIX B - PUBLICATIONS 

The Asphalt Handbook, Asphalt Institute, MS-4, 1989 Edition 

Asphalt Pavement Repair Manuals of Practice: 

Materials and Procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavements. 

Materials and Procedures for the Repair of Potholes in Asphalt-Surfaced Pavements, 

Strategic Highway Research Program (SHRP), 1999, R&T Report Center, 9701 Philadelphia Court, 

Unit Q, Lanham, MD 20706. www.fhwa.dot.gov/pavement/ltpp/mofpract.cfm 

Asphalt Pavement Maintenance: Field Guide, Minnesota Local Roads Research Board, 395 John 

Ireland Blvd., St. Paul, MN, MS 330, January 2002 

Asphalt Paving Principles, Cornell Local Roads Program, Publication 04-03 

A Basic Asphalt Emulsion Manual, Asphalt Institute, MS-19, Third Edition 

Best Practices Handbook on Asphalt Pavement Maintenance, Ann M. Johnson, P.E. 

Minnesota T2/LTAP Program, Center for Transportation Studies, University of Minnesota 

511 Washington Avenue S.E., Minneapolis, MN 55455-0375 

Chip Seal Best Practices: A Synthesis of Highway Practice, National Cooperative Highway Research 

Program, Washington, DC, NCHRP Synthesis 342, 2005 

Distress Identification Manual for the Long-Term Pavement Performance Project, 

Federal Highway Administration, FHWA-RD-03-031, 2003 

www.fhwa.dot.gov/pavement/pub_details.cfm?id=91 

Distress Identification Guide from the Long-Term Pavement Performance Program, 

North Dakota Local Technical Assistance Program, Publication #LTAP-05-001, August 2005 

Gravel Roads Maintenance and Design Manual, Ken Skorseth and Ali Salem, South Dakota Local 

Technical Assistance Program, Report #LTAP-02-002, April 2002 

Inspector’s Job Guide and Highway Maintenance Tables, Cornell Local Roads Program 

Local Government Handbook: 5th Edition, New York State Department of State, Division of Local 

Government, Albany, NY, January 2000 www.dos.state.ny.us/lgss/list9.html 

Pavement Preservation: Design and Construction of Quality Preventative Maintenance Treatments, 

FHWA, National Highway Institute Course No. 131103, November 2004 

Problems Associated with Gravel Roads, Federal Highway Administration, FHWA-SA-98-045, 1998 

Road Red Book of the Bureau of the Town Highways, State of New York Department of Highways, 

Bulletin No. 1, 1910 

Roadway and Roadside Drainage, Cornell Local Roads Program, Publication #98-5 

Roadway Maintenance Guide, James D. Thorne, American Public Works Assoc., Kansas City, MO 

Selecting a Preventative Maintenance Treatment for Flexible Pavements, Federal Highway 

Administration, FHWA-IF-00-027, August 2000 

http://www.fhwa.dot.gov/pavement/pub_details.cfm?id=27 

Standard Specifications Construction and Materials, New York State Department of Transportation, 

Plan and Publication Sales, 50 Wolf Rd., Albany, NY 12232 


APPENDIX C - VIDEOS 

The following videos are available on loan from the Cornell Local Roads Program: 

Asphalt Paving Inspection, Federal Highway Administration 

CLRP Tape #RM241 

Asphalt Crack Treatment, Minnesota Local Roads Research Board 

CLRP Tape #RM256 

Frost Action in Soils, U.S. Army Corps of Engineers 

CLRP Tape #WM128 

Sealcoating: A Matter of Science and Skill, Minnesota Local Roads Research Board, 1993. CLRP 

Tape #RC178 

Weather and Loads: The Effect They Have on Roads, Minnesota Local Roads Research Board CLRP 

Tape #RD133 


APPENDIX D - RESOURCES 

American Association of State Highway and Transportation Officials (AASHTO) 

444 N. Capital Street, NW, Suite 249, Washington, D. C. 20001 

(202) 624-5800 www.transportation.org 

American Public Works Association (APWA) 

2345 Grand Boulevard, Suite 500, Kansas City, MO 64108-2641 

(800) 848-2792 www.apwa.net 

American Road and Transportation Builders Association (ARTBA) 

The ARTBA Building, 1219 28th Street, N.W., Washington, DC 20007-3389 

(202) 289-4434 www.artba.org 

Association of Towns of the State of New York 

146 State Street, Albany, NY 12207 

(518) 465-7933 www.nytowns.org 

Asphalt Institute 

2696 Research Park Drive, Lexington, KY 40511-8480 

(859) 288-4960 www.asphaltinstitute.org 

Better Roads Magazine (subscription free to public works officials) 

2720 S. River Road #126, Des Plaines, IL 60018 

(847) 391-9070 www.betterroads.com 


416 Riley-Robb Hall, Cornell University, Ithaca, NY 14853-5701 

(607) 255-8033 www.clrp.cornell.edu 

Dig Safely New York 

3650 James Street, Syracuse, NY 13206 

1-800-962-7962 www.ufpo.org 

Federal Highway Administration - Long Term Pavement Performance Program 

Customer Service: 202-493-3035 Email: ltppinfo@fhwa.dot.gov 

Website: www.fhwa.dot.gov/pavement/ltpp/index.cfm 

Foundation for Pavement Preservation 

8613 Cross Park Drive, Austin, TX 78754 

1-866-862-4587 www.fp2.org 

International Slurry Surfacing Association 

3 Church Circle, PMB 250, Annapolis, MD 21401 

(410) 267-0023 www.slurry.org 

National Association of County Engineers (NACE) 

440 First Street, N.W., Washington, D.C. 20001-2028 

(202) 393-5041 www.countyengineers.org 

New York State Association of Town Superintendents of Highways, Inc. 

PO Box 427, Belfast, NY 14711 

(585) 365-9380 www.nysaotsoh.org 


New York State Conference of Mayors and other Municipal Officials (NYCOM) 

119 Washington Avenue, 2nd Floor, Albany, NY 12210 

(518) 463-1185 www.nycom.org 

New York State Department of State 

41 State Street, Albany, NY 12231-0001 

(518) 473-3355 www.dos.state.ny.us 

New York State County Highway Superintendents’ Association 

119 Washington Avenue, Albany, NY 12210 

(518) 465-1694 www.countyhwys.org 

New York State Office of General Services 

Empire State Plaza, Albany, NY 12242 

www.ogs.state.ny.us 

South Dakota Local Technical Assistance Program (LTAP) 

Box 2220, SDSU, Harding Hall, Brookings, SD 57007-0199 

(605) 688-4185 sdltap.sdstate.edu 


APPENDIX E - NYSDOT REGIONAL OFFICES 

NYSDOT Web Site: www.dot.state.ny.us 

Main Office: 50 Wolf Road, Albany NY 12232 (518) 457-4422 

Region 1 

328 State Street, Schenectady, NY 12305, (518) 388-0388 

Region 2 

207 Genesee Street, Utica, NY 13501, (315) 793-2447 

Region 3 

333 E. Washington Street, Syracuse, NY 13202, (315) 428-4351 

Region 4 

1530 Jefferson Road, Rochester, NY 14623, (585) 272-3300 

Region 5 

125 Main Street, Buffalo, NY 14203, (716) 847-3238 

Region 6 

107 Broadway, Hornell, NY 14843, (607) 324-8404 

Region 7 

317 Washington Street, Watertown, NY 13601, (315) 785-2333 

Region 8 

4 Burnett Boulevard, Poughkeepsie, NY 12603, (845) 431-5750 

Region 9 

44 Hawley Street, Binghamton, NY 13901, (607) 721-8116 

Region 10 

2250 Veterans Memorial Highway, Hauppauge, NY 11788, (516) 952-6632 

Region 11 

One Hunters Point Plaza, 47-40 21st Street, Long Island City, NY 11101, (718) 482-4526 


APPENDIX F - GLOSSARY 

AASHTO - American Association of State Highway Transportation Officials 

AADT - The Annual Average Daily Traffic - can refer to one-way or two-way traffic. 

Annual Costs - Any cost associated with the annual maintenance and repair of the facility. 

Asphalt Emulsion Mix - A mixture of emulsified asphalt materials and mineral aggregate 

usually prepared in a conventional hot-mix plant or drum mixer at a temperature of not 

more than 260°F (127°C). It is spread and compacted at the job site at a temperature above 

200°F (93°C). 

Cape Seal - A thin wearing course that involves the application of a slurry seal a few days after 

placing a chip seal. Cape seals are used to provide a dense, waterproof surface with 

improved skid resistance. 

Chip Seal - A thin wearing course in which a pavement surface is sprayed with asphalt (usually 

emulsified), then immediately covered with aggregate and rolled. Chip seals are used 

primarily to seal the surface of a pavement which has non load-associated cracks, and to 

improve surface friction. They are also used as a wearing course on low-volume roads. 

Cold In-Place Recycling (CIR) - A process in which a portion of an existing bituminous 

pavement is pulverized or milled, the reclaimed material is mixed with new binder and 

virgin materials, and the resultant blend is placed as a base for a subsequent overlay. 

Emulsified asphalt is especially suited for cold in-place recycling. Although not necessarily 

required, a softening agent may be used along with the emulsified asphalt. 

Cold Milling - A process of removing pavement material from the surface of the pavement 

either to prepare the surface (by removing rutting and surface irregularities) to receive 

overlays, to restore pavement cross slopes and profile, or to re-establish the pavement’s 

surface friction characteristics. 

Crack Filling - A maintenance procedure that involves placement of materials into non-working 

cracks to substantially reduce infiltration of water and to reinforce the adjacent pavement. 

Crack filling is not the same as crack sealing. 

Crack Sealing - A maintenance procedure that involves placement of specialized materials, 

either above or into working cracks, using unique configurations to reduce the intrusion of 

debris into the crack, and to prevent intrusion of water into the underlying pavement layers. 

Dense-Graded Asphalt Overlay - An overlay course consisting of a mix of asphalt cement and 

a well-graded (also called dense-graded) aggregate. A well-graded aggregate is uniformly 

distributed throughout the full range of sieve sizes. 

Emulsified Asphalt - A mixture of asphalt cement and water, which contains a small amount of 

an emulsifying agent. Emulsified asphalt droplets, which are suspended in water, may be 

either the anionic (negative charge) or cationic (positive charge) type, depending upon the 

emulsifying agent. 

Fog Seal - A light application of slow setting asphalt emulsion diluted with water. It is used to 

renew old asphalt surfaces and to seal small cracks and small surface voids. 



Heater Scarification - A form of Hot In-Place Recycling in which the surface of the old 

pavement is heated, scarified with a set of scarifying teeth, mixed with a recycling agent, 

and then leveled and compacted. 

Hot In-Place Recycling (HIR) - A process which consists of softening the existing asphalt 

surface with heat, mechanically removing the surface material, mixing the material with a 

recycling agent, adding (if required) virgin asphalt or aggregate to the material, and then 

compacting the material back on the pavement. 

Hot Mix Asphalt (HMA) - A high-quality, hot mixture of asphalt cement and well-graded, highquality 

aggregate, thoroughly compacted into a uniform dense mass. 

Hot Surface Recycling - See hot in-place recycling. 

Initial Costs - All costs associated with the initial design and construction of a facility, 

placement of a treatment, or any other activity with a cost component. 

Life Cycle Cost - The present value, in dollars, of initial cost, plus annual maintenance cost, plus 

road user cost. 

Microsurfacing - A mixture of polymer modified asphalt emulsion, mineral aggregate, mineral 

filler, water, and other additives, properly proportioned, mixed and spread on a paved 

surface. 

Mineral Filler - A finely divided mineral product, at least 70 percent of which will pass a 

0.075 mm (No. 200) sieve. Pulverized limestone is the most commonly manufactured filler, 

although other stone dust, hydrated lime, portland cement, and certain natural deposits of 

finely divided mineral matter are also used. 

Novachip TM - A thin wearing course placed on existing pavements. Sometimes called an 

ultrathin friction course, it consists of a layer of hot-mix material placed over a heavy, 

polymer modified emulsified asphalt tack coat. The total thickness of the application is 

typically between 0.40 and 0.80 inch (10 and 20 mm). It can be used to reduce deterioration 

caused by weathering, raveling, and oxidation, and also to fill ruts and to smooth 

corrugations and other surface irregularities. 

Open-Graded Friction Course (OGFC) - A thin wearing course consisting of a mix of asphalt 

cement and open-graded (also called uniformly-graded) aggregate. An open-graded 

aggregate consists of particles of predominantly a single size. 

Partial-Depth Recycling - See cold in-place recycling. 

Pavement Preservation - The sum of all activities undertaken to provide and maintain 

serviceable roadways; this includes corrective maintenance and preventive maintenance, as 

well as minor rehabilitation projects. 

Pavement Preventive Maintenance - A planned strategy of cost-effective treatments to an 

existing roadway system and its appurtenances, which preserves the system, retards future 

deterioration, and maintains or improves the functional condition of the system (without 

increasing the structural capacity). 

Pavement Reconstruction - Construction of a new pavement structure, which usually involves 

complete removal and replacement of the existing pavement surface and base, using new 

and/or recycled materials. 


Appendix F - Glossary 

Pavement Rehabilitation - Work undertaken to extend the service life of an existing pavement. 

This includes the restoration, placing an overlay, and/or other work required to return an 

existing roadway to a condition of structural and functional adequacy. 

Recycling Agents - Organic materials with chemical and physical characteristics selected to 

address any binder deficiencies and to restore aged asphalt material to desired 

specifications. 

Rejuvenating Agent - Similar to recycling agents in material composition, these products are 

added to existing aged or oxidized AC pavements in order to restore flexibility and retard 

cracking. 

Rubberized Asphalt Chip Seal - A variant of conventional chip seals in which the asphalt 

binder is a blend of ground tire rubber (or latex rubber) and asphalt cement, to enhance the 

elasticity and adhesion characteristics of the binder. Commonly used in conjunction with an 

overlay to retard reflection cracking. 

Sand Seal - An application of asphalt material covered with fine aggregate. Used to improve the 

skid resistance of slippery pavements and to seal against air and water intrusion. 

Sandwich Seal - A surface treatment that consists of application of a large aggregate, followed 

by a spray of asphalt emulsion that is in turn covered with an application of smaller 

aggregate. Sandwich seals are used to seal the surface and improve skid resistance. 

Scrub Seal - Application of a polymer modified asphalt to the pavement surface, followed by the 

broom-scrubbing of the asphalt into cracks and voids, then the application of an even coat 

of sand or small aggregate, and finally a second brooming of the aggregate and asphalt 

mixture. This seal is then rolled with a pneumatic tire roller. 

Slurry Seal - A mixture of slow-setting emulsified asphalt, well-graded fine angular aggregate, 

mineral filler, and water. It is used to fill cracks and seal areas of old pavements, to restore 

a uniform surface texture, to seal the surface to prevent moisture and air intrusion into the 

pavement, and to provide skid resistance. 

Stockpiled Cold Mix - A maintenance mix consisting of aggregate and emulsified asphalt, 

which can be stored and readily used for up to six months, depending on the formulation of 

the emulsion used and the aggregate characteristics. 

Stone Mastic Asphalt Overlay - An overlay course consisting of a mix of asphalt cement, 

stabilizer material, mineral filler, and gap-graded aggregate. A gap-graded aggregate is 

similar to an open-graded material but is not quite as open. 

Surface Texture - The characteristics of the pavement surface that contribute to surface friction 

and tire noise. 

User Costs - Costs incurred by highway users traveling on the facility and the excess costs 

incurred by those who cannot use the facility because of either agency or self-imposed 

detour requirements. User costs are typically comprised of vehicle operating costs (VOC), 

accident costs, and user delay costs. 

Working Crack - cracks which experience significant horizontal movements, generally greater 

than about 2 mm (0.1 in).

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