Improving the Properbes of Reclaimed Asphalt Pavement for ...

Improving the Proper/es of 

Reclaimed Asphalt Pavement for 

Roadway Base Applica/ons Final 

Report 

David Horhota, Ph.D., P.E. PM 

Paul Cosen/no, Ph.D., P.E. PI 

Edward Kalajian, Ph.D., P.E. PI 

Albert Bleakley Ph.D., P.E. 

Babacar Diouf 

Ryan Krajcik 

August 16, 2012 

Thaddeus Misilo III 

Andrew Petersen 

Amir Mohammad Sajjadi

Problem Statement 

! FDOT specifica/ons only allow RAP to be reused as a 

base in non-‐trafficked areas 

! Florida’s Aggregate produc/on does not meet needs 

! Aggregates are hauled in from as far away as Central 

America and Nova Sco/a 

! 10 mile I-‐95 widening project Brevard County 

! reusing RAP in base would save 40,000 tons of material 

! $800,000 -‐ $1,000,000 es/mated savings

Problem Statement 

! Two problems limit RAP use: 

! Low strength 

! Creep deforma/on 

! FDOT specifica/ons use the Limerock Bearing 

Ra/o (LBR) strength 

! Required LBR is 100 (800 psi) for base material 

! RAP LBR typically between 10 & 30 

! RAP creep leads to ru`ng

Outline 

! Objec/ve 

! Tasks 

! Results 

! Frac/ona/ng 

! Compac/on 

! Blending 

! Chemical Stabiliza/on 

! Conclusions &Recommenda/ons 

! Ques/ons

Objec/ve 

v Develop engineering methods to improve 

bearing ra/os while reducing creep 

v Leads to increased use of RAP as a base 

course.

Tasks 

! Task 1 – Literature Review 

! Task 2 – Tes/ng Program Development 

! Task 3 – Grada/on Modifica/on (Frac/ona/ng) 

! Task 4 – Blends with High Quality Base 

! Task 5 – Asphalt Content Evalua/ons 

! Task 6 – Compac/on Improvements Using 

! Mechanical Energy 

! Chemical Admixtures

Literature Review Focus 

! General Characteris/cs of RAP 

! Current use of RAP or RAP blends as base 

! Compac/on of RAP or RAP/aggregate blends 

! Blending of RAP and virgin aggregates 

! Use of chemical stabilizing addi/ves with RAP 

including Cold In-‐place Recycling (CIR) or Full 

Depth Reclama/on (FDR) pavement restora/on 

! Creep behavior of soils and RAP 

! Mathema/cal modeling of the rheological 

response of viscoelas/c materials to stress

Rela/ve Effects of increasing RAP 

content 

Reference Blends Dry Density Permeability CBR 

! McGarrah (2007) literature summary 

Resilient 

Modulus 

Cooley (2005) Yes Decreased -‐-‐-‐ Decreased -‐-‐-‐ 

Garg & Thompson (1996) No Decreased -‐-‐-‐ Decreased -‐-‐-‐ 

MacGregor (1999) Yes -‐-‐-‐ No Change -‐-‐-‐ Increased 

Bennert & Maher (2005) Yes Decreased Decreased -‐-‐-‐ Increased 

Papp (1998) Yes Decreased -‐-‐-‐ -‐-‐-‐ Increased 

Sayed (1993) No -‐-‐-‐ -‐-‐-‐ Decreased -‐-‐-‐ 

Taha (1999) Yes Decreased Increased Decreased -‐-‐-‐ 

Trzebiatowski (2005) No Decreased Increased -‐-‐-‐ -‐-‐-‐

Current RAP Specifica/ons 

! McGarrah 

(2007) 

Summary of 

state 

prac/ces 

State 

RAP 

Allowed 

Max % Processed Tes4ng 

Florida No -‐-‐-‐ -‐-‐-‐ -‐-‐-‐ 

Illinois No -‐-‐-‐ -‐-‐-‐ -‐-‐-‐ 

Montana Yes 50-‐60% No 

Corrected Nuc 

Gauge 

New Jersey Yes 50% 5 Yes 

Grada/on 

Corrected Nuc 

Gauge + Sample 

Minnesota Yes 3% 6 Yes 

Grada/on 

Dynamic Cone 

Penetrometer 

Colorado Yes 50% 5 Yes Max 

Agg. Size 

Roller Compac/on 

Strip 

Utah Yes 2% 6 Yes 

Grada/on 

Nuc Gauge or 

Breakdown Curve 

Texas7 Yes 20% Unknown 

Various (Including 

Nuc Gauge) 

California7 Yes 50% Unknown 

No special tes/ng 

procedure listed 

New 

Mexico7 Yes Unknown Unknown 

Corrected Nuc 

Gauge 

Rhode 

Island7 Yes Unknown 

Yes 

Grada/on 

Unknown 

South 

Dakota7 No -‐-‐-‐ -‐-‐-‐ -‐-‐-‐

Creep Theory for Soils 

Singh and Mitchell (1968) developed a model to 

m 

describe creep of clays. 

αD 

⎛⎛ t1 

⎞⎞ 

> 90 % failure 

30 to 90 % failure 

< 30 % failure 

ε = Ae ⎜⎜ ⎟⎟ 

⎝⎝ t ⎠⎠ 

A – log strain rate vs. deviator 

stress and finding the 

intercept when D = 0. 

m – slope of log strain versus 

log /me straight line. 

D – deviator stress 

α – slope of the linear por/on 

of the logarithm strain versus 

deviator-‐stress plot. 

t 1 – reference /me (1 day) 

t – /me

Creep Compliance (%/psi) 

0.18 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

Background and Theory 

Creep Behavior of RAP/A-‐3 Blends 

RAP100-B6 

RAP100-B12 

RAP100-B24 

RAP80-B6 

RAP80-B12 

RAP80-B24 

RAP60-B6 

RAP60-B12 

RAP60-B24 

A3-B6 

A3-B12 

A3-B24 

Creep Compliance (%/psi) 

0 

0 

0 1 2 3 4 

Time (days) 

5 6 7 

0.0001 0.001 0.01 0.1 

Log Time (days) (days) 

1 10 

0.18 

0.16 

0.14 

0.12 

0.1 

0.08 

0.06 

0.04 

0.02 

RAP100-B6 

RAP100-B12 

RAP100-B24 

RAP80-B6 

RAP80-B12 

RAP80-B24 

RAP60-B6 

RAP60-B12 

RAP60-B24 

A3-B6 

A3-B12 

A3-B24 

Cleary (2005) and Dikova (2006) 

80% RAP/20% A-‐3 Sand 

100 % RAP

Laboratory Inves/ga/on Program 

! Test types 

! Index tests to describe the material 

! Strength tests to determine load capacity 

! Creep tests to determine suscep/bility to long-‐term 

deforma/on 

! Test materials 

! RAP, A-‐3 sand, limerock, cemented coquina, and 

crushed concrete base (FDOT spec) 

! 100% RAP, blends of RAP/aggregate base material 

containing 75%, 50%, and 25% RAP, and 100% 

aggregate base 

! 0%, 1%, 2%, and 3% stabilizing agent (asphalt 

emulsion, Portland cement or lime) by weight

Laboratory 

Tes/ng Example 

Soaked 

Marshall 

Compaction 

Curing 

Marshall 

Compression 

Testing 

Unsoaked 

Blending 

Anionic 

Emulsion 

6 in Mod 

Proctor 

Compaction 

Curing 

One 

Dimensional 

Creep 

Unsoaked 

LBR Testing 

Sampling 

Air Drying 

Crushing 

Blending 

Cationic 

Emulsion 

Mod 

Proctor 

Compaction 

Soaked 

Data 

Analysis 

Blending 

Portland 

Cement 

Curing 

Indirect 

Tensile 

Testing 

Gyratory 

Compaction 

Unsoaked 

Soaked 

4x8 Mod 

Proctor 

Compaction 

Curing 

Unconfined 

Compression 

Testing 

Unsoaked

Loca/ons 

! Sampling 

! Drying 

! Sample reduc/on 

! Oversize material 

Whitehurst Gainesville 

APAC Jacksonville 

14 

APAC Melbourne

Stabilizing Agents

Blending

Compac/on

Curing

Soaking

Creep Test

LBR Test

Marshall 

Test

Unconfined 

Compression Test

Indirect Tensile Test

RAP Index Proper/es 

Properties APAC - 

Melbourne 

APAC - 

Melbourne 

Whitehurst- 

Gainesville 

APAC - 

Jacksonville 

Milled Crushed Milled Crushed 

Passing #4 (%) 58.1 75.8 46.0 73.38 

Passing #8 (%) 32.8 50 42.0 55.27 

Passing #40 (%) 7.68 14.35 11.0 33.33 

Passing #200 (%) 0.50 0.60 0.30 6.82 

C u 9.80 10.7 12.0 28.0 

C c 1.73 0.94 0.88 0.32 

AASHTO A-1-a A-1-a A-1-a A-1-b 

USCS SW SW SW SW

Percent Finer (%) 

100% 

90% 

80% 

70% 

60% 

50% 

40% 

30% 

20% 

10% 

0% 

100 

Sieve Analysis 

Grain Size Distribution Curve 

10 

1 

Sieve Opening (mm) 

100% MMRAP 

75% MMRAP 

50% MMRAP 

25% MMRAP 

100% LR 

FDOT Max 

FDOT Min 

0.1 

0.01

% 

RAP 

Milled 

Melb. 

RAP/ 

Limerock 

Milled 

Melb. 

RAP/ 

Cemented 

Coquina 

Permeability 

Milled 

Melb. 

RAP/ 

Crushed 

Concrete 

Permeability (cm/s) 

Crushed 

Jax. 

RAP/ 

Limerock 

Crushed 

Jax. RAP/ 

Cemented 

Coquina 

Milled 

W.H. 

RAP/ 

Limerock 

Milled 

W.H. RAP/ 

Cemented 

Coquina 

100 3.1E-‐03 3.1E-‐03 3.1E-‐03 1.8E-‐05 1.8E-‐05 1.3E-‐04 1.3E-‐04 

50 3.2E-‐04 1.8E-‐05 1.2E-‐04 2.1E-‐05 5.5E-‐05 8.3E-‐05 3.6E-‐05 

25 3.2E-‐05 5.9E-‐06 1.4E-‐04 4.2E-‐06 5.4E-‐04 1.2E-‐06 2.7E-‐04 

0 

1.2E-‐06 3.0E-‐06 2.9E-‐05 1.2E-‐06 3.0E-‐06 1.2E-‐06 3.0E-‐06

Frac/ona/ng or Grada/on Modifica/on 

Thesis by: Babacar Diouf 

! 100% RAP 

! 2 sources for each crushed and milled RAP 

! Specimens of +/-‐ #4,#8,#40 and Talbot curve 

mixes 

! Creep and post creep LBR on each specimen

Results-‐Creep Tests 

Crushed APAC Melbourne 

Milled APAC Melbourne

Results-‐Post Creep LBR 

Crushed APAC Melbourne 

Milled APAC Melbourne

! RAP Frac/ons 

had lower LBR 

than non-‐ 

frac/onated 

RAP 

! Talbot blends 

(i.e. maximum 

density) 

improved LBR 

Post Creep LBR Comparisons

Compac/on Methods 

Thesis by: Andrew Petersen 

! Vibratory 

! Gyratory 

! Modified Proctor 

! Combina/on of Methods

LBR – Vibratory Compac/on 

! Weak linear increase 

in LBR as dry density 

increased 

! Approximate LBR 

increase 0.24 per 1 

pcf dry density 

! Maximum value of 

21 below FDOT 

specifica/on 

! Lower densi/es than 

mod Proctor or 

gyratory

Unsoaked LBR 

120 

100 

80 

60 

40 

20 

Modified Proctor – Gyratory Comparison: 

LBR 

Gyratory 

y = 2.65x - 245.63 

R² = 0.58 

Modified Proctor 

y = 0.58x - 51.28 

R² = 0.45 

0 

100 105 110 115 120 125 130 135 

Dry Density (pcf) 

FIT Gyratory FIT Mod. Proctor FDOT Gyratory FDOT Mod Proctor 

! Linear increase in 

LBR as dry density 

increased 

! Gyratory 

compacted 

specimens 2 -‐ 4 

/mes higher LBR 

than mod Proctor 

! Some unsoaked 

LBR over 100


Unconfined Compression (UCC) 

! Gyratory resulted 

in 2 to 3 /mes 

higher unconfined 

compressive 

strength than 

modified Proctor


Indirect Tensile Test 

! Gyratory resulted 

in 2 to 3 /mes 

higher indirect 

tensile strength 

than modified 

Proctor

Follow-‐on Proctor-‐Gyratory 

Comparison 

! Indirect Tensile and LBR tes/ng of three 

aggregate materials without asphalt binder 

! Limerock base 

! Cemented coquina 

! Clayey sand

Average Gyratory/Proctor Strength 

Ra/os

Displacement (in) 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

Gyratory – Proctor Unconfined Creep 

0 

0.01 0.10 1.00 

Log Time (days) 

100% RAP 

Average Proctor 100% LR no stab Average Gyratory 100% LR no stab 

! Ini/ally similar 

creep 

! Proctor 

specimen in 

ter/ary creep


0.009 

0.008 

0.007 

0.006 

0.005 

0.004 

0.003 

0.002 

0.001 


100% Limerock 

y = 0.0002ln(x) + 0.0069 

y = 0.0002ln(x) + 0.0011 

0 

0.01 0.10 1.00 



! Gyratory – 

Proctor same 

CSR 

! No ter/ary 

creep


0.014 

0.012 

0.01 

0.008 

0.006 

0.004 

0.002 


50% RAP/ 50% Limerock 

y = 0.0005ln(x) + 0.0098 

y = 0.0004ln(x) + 0.0076 

0 

0.01 0.10 1.00 


10.00 


! Gyratory – 

Proctor similar 

CSR 

! No ter/ary 

creep


0.04 

0.035 

0.03 

0.025 

0.02 

0.015 

0.01 

Gyratory Unconfined Creep 

Summary 

0.005 

100% Limerock 

0 

0.01 0.1 1 10 


100% MRAP 

50% MRAP/50% Limerock 

! 50%/50% 

blend creep 

similar to 

100% LR 

! No ter/ary 

creep 

! Proctor similar 

results (not 

shown)


0.014 

0.012 

0.01 

0.008 

0.006 

0.004 

0.002 

Unload/reload effect on creep 

y = 0.0005ln(x) + 0.0109 

y = 0.0003ln(x) + 0.0063 

0 

1.00 

Time (days) 

10.00 


! Both gyratory and 

modified Proctor 

compacted 

specimens 

rebounded 20% 

when unloaded 

! Arer reload, 

creep con/nued 

at same rate

Task 4 – Blending RAP with High 

Quality Materials 

Thaddeus (TJ) Misilo

Blends with High Quality Materials 

! Milled RAP 

! Select Base Materials 

! Limerock 

! Cemented Coquina 

! Recycled Concrete 

! Different Blend Combina/ons 

! 100% -‐ 0% 

! 75% -‐ 25% 

! 50% -‐ 50% 

! 25% -‐ 75% 

! Same tests as frac/onated samples

Dry Density [lb/ft 3 ] 

132 

130 

128 

126 

124 

122 

120 

118 

116 

Typical Dry Density and LBR 

vs. Moisture Content Plots 

100% Cemented Coquina 

75/25% CCB / MMRAP 


25/75% CB / MMRAP 

114 

2 4 6 8 

Moisture Content [%] 

10 12 14 

LBR 

10 3 

10 2 

10 1 





2 4 6 8 

Moisture Content [%] 

10 12 14

CCR [in/in/psi/day] 

Cemented Coquina Blends 

CCR vs. Creep Loading Pressure 

10 -3 

10 -4 

10 -5 

10 -6 

10 -7 

10 1 


75/25% CCB/MMRAP 



Creep Loading Pressure [psi] 

10 2

Strain [in/in] 

0.04 

0.035 

0.03 

0.025 

0.02 

0.015 

0.01 

0.005 

10 -3 

100% Limerock - Mold 53 

Creep Test Results Limerock 

100% Limerock - Mold 55 

75/25% LR/MMRAP - Mold 32 






10 -2 

100 psi vs. Log Time 

10 -1 

Time [days] 

10 0 

10 1 

10 2

Unsoaked LBR 

10 3 

10 2 

10 1 

Blend Summary 

Unsoaked LBR vs. 

% Milled Melbourne RAP 

Limerock 

Cemented Coquina 

Recycled Concrete 

0 10 20 30 40 50 60 70 80 90 100 

Milled Melbourne RAP [%]

Effect of Blending on LBR and Creep 

Description 

Unsoaked 

LBR 

Acceptable Soaked 

LBR 

Acceptable 

30 Year 

Deformation Acceptable 

10 in base, 25 psi 

Limerock MRAP 

100 0 180 Yes 162 Yes 0.08 Yes 

75 25 225 Yes 99 No 0.12 Yes 

50 50 82 No 55 No 0.15 Yes 

25 75 43 No NP No 0.28 Yes 

0 100 31 No NP No 0.56 No 

Cemented Coquina MRAP 

100 0 216 Yes 63 No 0.07 Yes 

75 25 150 Yes 93 No 0.08 Yes 

50 50 79 No NP No 0.17 Yes 

25 75 40 No NP No 0.44 No 

0 100 31 No NP No 0.56 No 

Recycled Reclaimed Concrete Concrete 

Aggragate MRAP 

100 0 159 Yes 162 Yes 0.07 Yes 

75 25 76 No NP No 0.08 Yes 

50 50 48 No NP No 0.13 Yes 

25 75 30 No NP No 0.43 No 

0 100 31 No NP No 0.56 No 

NP -‐ Soaked LBR test not performed since Unsoaked LBR was below 100

Task 6b – Compac/on Improvements 

Using Chemical Admixtures 

Albert Bleakley

Unsoaked LBR vs RAP Content 

Unsoaked LBR (no units) 

300 

250 

200 

150 

100 

50 

0 

0% 25% 50% 75% 100% 

RAP Content (%) 

100% MRAP 75% MRAP/ 25% LR 60% MRAP/ 40% LR 55% MRAP/ 45% LR 

50% MRAP/ 50% LR 25% MRAP/ 75% LR 100% LR 

y = -213.31x + 206.5 

R² = 0.849

Creep Strain Rate vs RAP Content 

Creep Strain Rate (in/in/log(t)) 

3.00E-03 

2.50E-03 

2.00E-03 

1.50E-03 

1.00E-03 

5.00E-04 

y = 0.0026x + 4E-05 

R² = 0.718 

0.00E+00 

0% 25% 50% 75% 100% 

RAP Content (%) 

100% MRAP 75% MRAP/ 25% LR 60% MRAP/ 40% LR 

55% MRAP/ 45% LR 50% MRAP/ 50% LR 25% MRAP/ 75% LR 

100% LR


600.0 

500.0 

400.0 

300.0 

200.0 

100.0 

CSS-‐1H Stabilized MRAP/Limerock Blends 

0.0 

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 

% CSS-1H 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 

100% LR 

25% MRAP/75% LR 

0.0035 

0.0030 

0.0025 

0.0020 

0.0015 

0.0010 

0.0005 

0.0000 

0.0% 1.0% 2.0% 

% CSS-1H 

3.0% 

100% MRAP 

50% MRAP/50% LR 

100% LR 

75% MRAP/25% LR 

25% MRAP/75% LR 

! Large LBR improvement from blending (6x – 12x) 

! 10% -‐ 20% LBR improvement from 1% CSS-‐1H 

! Large creep reduc/on from blending (.7x -‐ .1x) 

! 10% -‐ 20% creep improvement from 1% CSS-‐1H 

Creep Strain Rate (Δstrain/Δlog time)


SS-‐1H stabilized MRAP/limerock (48 hr oven) 

600.0 

500.0 

400.0 

300.0 

200.0 

100.0 

0.0 

0.0% 0.5% 1.0% 1.5% 

% SS-1H 

2.0% 2.5% 3.0% 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75%LR 

100% LR 

0.0035 

0.0030 

0.0025 

0.0020 

0.0015 

0.0010 

0.0005 

0.0000 

0.0% 1.0% 2.0% 

% SS-1H 

3.0% 

! Large LBR improvement from blending (1.5x – 4x) 

! 10% -‐ 20% LBR improvement from 1% SS-‐1H 

! Large creep reduc/on from blending (.7x -‐ .1x) 

! Mixed creep improvement from 1% SS-‐1H 

Creep Strain Rate (Δstrain/Δlog time) 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR


Cement Stabilized MRAP/Limerock Blends 

800 

700 

600 

500 

400 

300 

200 

100 

0 

0.0% 1.0% 

% Cement 

2.0% 3.0% 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

0.0035 

0.0030 

0.0025 

0.0020 

0.0015 

0.0010 

0.0005 

0.0000 

0.0% 1.0% 2.0% 

% Cement 

3.0% 

! Large LBR improvement from blending (1.5x – 4x) 

! 20% -‐ 40% LBR improvement from 1% cement 

! Large creep reduc/on from blending (.7x – .1x) 

! 30% -‐ 90% creep reduc/on from 1% cement 


100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR


800 

700 

600 

500 

400 

300 

200 

100 

Summary of Stabilized 50% RAP/LR 

0 

0.0% 1.0% 2.0% 3.0% 

% Stabilizing Agent 

SS-1H CSS-1H PC 

Blends 

0.0025 

0.0020 

0.0015 

0.0010 

0.0005 

! Large LBR improvement from blending 

0.0000 

0.0% 1.0% 2.0% 3.0% 

! Emulsions show LBR peak at 1%; cement does not 

! Emulsions show mixed creep results at 1%; cement 

decreases creep 



SS-1H CSS-1H PC

Unsoaked Compressive Stress (psi) 

Unconfined Compression Blends with CSS-‐1H 

300 

250 

200 

150 

100 

50 

Unsoaked 

0 

0% 1% % CSS-1HF 2% 3% 

75% MRAP/25% LR 50% MRAP/50% LR 

25% MRAP/75% LR 100% MRAP 

100% LR 

0 

0% 1% 2% 

% CSS-1HF 

3% 

! Blending increased UCC strength 10% -‐ 90% 

! UCC strength increased 2.5x – 3.5x with 1% CSS-‐1H 

! Blending decreased peak displacement 10% -‐ 40% 

! Peak displacement increased with CSS-‐1H content 

Soaked Compressive Stress (psi) 

300 

250 

200 

150 

100 

50 

Soaked 

75% MRAP/25% LR 50% MRAP/50% LR 

25% MRAP/75% LR 100% MRAP 

100% LR

Unsoaked Strength (psi) 

Unconfined Compression Blends with CSS-‐1H 

300 

250 

200 

150 

100 

50 

0 

Unsoaked LR 

0% 1% 2% 3% 

% SS-1H 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

Soaked Strength (psi) 

300 

250 

200 

150 

100 

50 

0 

Unsoaked LR 

0% 1% 2% 3% 

% SS-1H 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR

Unsoaked Compressive Stress (psi) 

Unconfined Compression Blends with SS-‐1H 

300 

250 

200 

150 

100 

50 

Unsoaked 

0 

0% 1% 

% SS-1H 

2% 3% 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

Soaked Compressive Stress 

(psi) 

0 

0% 1% 

% SS-1H 

2% 3% 

! Blending increased UCC strength 10% -‐ 90% 

! UCC strength increased 1.1x -‐ 4x with 1% SS-‐1H 


! Peak displacement increased with SS-‐1H content 

300 

250 

200 

150 

100 

50 

Soaked 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR


Unconfined Compression Blends with SS-‐1H 

300 

250 

200 

150 

100 

50 

0 

Unsoaked LBR 100% LR 

0% 1% 2% 3% 

% SS-1H 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 


300 

250 

200 

150 

100 

50 

0 

0% 1% 2% 3% 

% SS-1H 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR

Unsoaked Compressive Strength (psi) 

500 

400 

300 

200 

100 

Unconfined Compression Blends with 

0 

0% 1% 2% 3% 

% Portland Cement 

75% MRAP/25% LR 

25% MRAP/75% LR 

100% LR 

50% MRAP/50% LR 

100% MRAP 

Portland Cement 

0 

0% 1% 2% 3% 

! Blending increased unsoaked UCC strength 10% -‐ 90% 


! Peak displacement unchanged with cement content 

Soaked Compressive Strength (psi) 

500 

400 

300 

200 

100 

% Portland Cement 

75% MRAP/25% LR 50% MRAP/50% LR 25% MRAP/75% LR 

100% MRAP 100% LR


Unconfined Compression Portland Cement 

500 

400 

300 

200 

100 

0 

Unsoaked LR 

% Cement 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

! UCC unsoaked strength increased 10% -‐ 30% with 1% 

cement 

! UCC soaked strength increased 50% -‐ 400% with 1% 

cement 


500 

400 

300 

200 

100 

0 

Unsoaked LR 

% Cement 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR

Marshall NStability (lb) 

Modified Marshall .05 ipm vs 2.0 ipm 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

0 

Unstabilized 1% PC 1% SS-1H 

.05 ipm 2.0 ipm 

Marshall Flow (.01 in) 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

Unstabilized 1% PC 1% SS-1H 

.05 ipm 2.0 ipm

Unsoaked Marshall Stability (lb) 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

Modified Marshall Blends with CSS-‐1H 

0 

0% 1% 2% 

% CSS-1HF 

3% 

! All blends peaked between 1% and 2% CSS-‐1H 

! Marshall flow (not shown) increased with increasing 

CSS-‐1H 

Unsoaked 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

Soaked Marshall Stability (lb) 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

Soaked 

0 

0% 1% 

% CSS-1HF 

2% 3% 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR

Retained Strength (Soaked/Unsoaked) 

Modified Marshall Blends with CSS-‐1H 

100% 

90% 

80% 

70% 

60% 

50% 

40% 

30% 

20% 

10% 

0% 

0% 1% 2% 3% 

% CSS-1HF 

100% MRAP 75% MRAP/25% LR 50% MRAP/50% LR 

25% MRAP/75% LR 100% LR 

! Large increase 

in retained 

strength 

! SS-‐1H gave 

similar results

Unsoaked Marshall Stability (lb) 

20000 

15000 

10000 

5000 

Modified Marshall Blends with Cement 

Unsoaked 

0 

0% 1% 2% 3% 

% Cement 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR 

Soaked Marshall Stability (lb) 

20000 

15000 

10000 

5000 

Soaked 

0 

0% 1% 2% 3% 

% Cement 

100% MRAP 75% MRAP/25% LR 

50% MRAP/50% LR 25% MRAP/75% LR 

100% LR

Retained Strength (Soaked/Unsoaked) 

Modified Marshall Blends with Cement 

100% 

90% 

80% 

70% 

60% 

50% 

40% 

30% 

20% 

10% 

0% 

Retained Strength 

0% 1% 2% 3% 

% Cement 

100% MRAP 75% MRAP/25% LR 50% MRAP/50% LR 

25% MRAP/75% LR 100% LR 

Large 

increase in 

retained 

strength, 

par/cularly at 

high limerock 

contents

Indirect Tensile Stress (psi) 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

Indirect Tensile Test 50% MMRAP with 

Stabilizer 

0% Stabilizer 

1% Stabilizer 

* 100% RAP and 100% Limerock are unstabilzed 

! Blending increased unsoaked IDT strength by 20% over 

100% MRAP; 30x over 100% limerock 

! 1% stabilizing agent increased unsoaked IDT by 15% 

! Blending decreased soaked IDT strength by 60% 

compared to 100% MRAP; but >> 100% LR (IDT = 0) 

! 1% stabilizing agent increased soaked IDT 4x – 6x 

Indirect Tensile Stress (psi) 

30.0 

25.0 

20.0 

15.0 

10.0 

5.0 

0.0 

SS-1H 

Soaked 

CSS-1HF 

Soaked 

PC 

Soaked 

100% 

MMRAP* 

0% Stabilizer 

1% Stabilizer 

100% LR 

Soaked* 

* 100% RAP and 100% Limerock are unstabilzed

Soaked LBR 

Summary of Soaked LBR of Stabilized 

400 

350 

300 

250 

200 

150 

100 

50 

50% MRAP/50% LR blends 

0 

0.0% 1.0% 2.0% 3.0% 


SS-1H CSS-1HF PC 

25% MRAP/ 75% LR 100% LR 100% LR FDOT 

Emulsion and 

cement 

stabilized 

50%/50% 

blends had 

soaked LBR 

over 100

Settlement (in) 

Creep Models – 30 Year Creep of 10 inch 

0.14 

0.12 

0.10 

0.08 

0.06 

0.04 

0.02 

Base at 25 psi Constant Stress 

y = 1.71E-03ln(x) + 1.07E-01 

R² = 8.42E-01 

y = 1.73E-03ln(x) + 7.45E-02 

R² = 9.06E-01 

0.00 

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 

Time (days) 

50% MRAP no stab 12 psi 50% MRAP no stab 25 psi 

Mitchell Model 12 psi Mitchell Model 25 psi 

CSR Projection 12 psi CSR Projection 25 psi 

50% RAP/50% 

LR with 1% 

cement has 

acceptable 

creep (

Projected 30 Year Creep Settlement (in) 

Summary of 30 Year Creep of 10 inch 

Base at 12 and 25 psi Constant Stress 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

12 psi CSR 12 psi SM 25 psi CSR 25 SM 

Model and Pressure 

100% MRAP 50% MRAP 50% MRAP 1% PC 100% LR 

! Unstabilized 

50%/50% 

blends ok at 

12 psi, 

marginal at 25 

psi 

! Stabilized 

50%/50% 

blends ok at 

25 psi

Conclusions 

! Frac/ona/ng RAP did not improve strength or creep 

performance 

! Laboratory gyratory compac/on greatly increased 

strength of RAP or RAP/aggregate blends 

! Blending RAP with aggregates improved permeability by 

1 – 3 orders of magnitude 

! Blends of 50% or less RAP behave more like a 

conven/onal aggregate with greatly reduced creep and 

higher strength 

! Blends of RAP/A-‐3 sand, RAP/Cemented Coquina, and 

RAP/crushed concrete had LBRs < 100

Conclusions 

! 50% RAP/limerock blends without stabilizing agent 

achieved a soaked LBR of 53. This meets the subbase 

specifica/on (40) but not the base specifica/on (100). 

! 50% RAP/limerock blends showed projected creep 

strain of approximately 3% over 30 years at 25 psi 

constant stress making them marginal for base 

course. Projected creep at 12 psi was under 1% 

making 50%/50% blends acceptable for subbase. 

! 25% RAP/limerock blends without stabiliza/on 

achieved a soaked LBR of 98.7 with very low creep. 

This blend may be acceptable for base course.

Conclusions 

! Asphalt emulsion stabilized RAP/limerock 

blends showed a peak LBR and creep 

reduc/on at approximately 1% emulsion 

! Cement stabilized RAP/limerock blends 

con/nued to increase in LBR and decrease 

creep with increasing cement content 

! Lime stabiliza/on of RAP/limerock blends did 

not appreciably improve LBR or decrease 

creep

Conclusions 

! 50% RAP/limerock blends stabilized with either 

asphalt emulsion or Portland cement reached 

soaked LBR values over 100. 

! 50% RAP/limerock blends stabilized with cement 

showed projected creep strain of approximately 

1% over 30 years at 25 psi constant stress making 

them acceptable for base course. 

! 50% RAP/limerock blends stabilized with asphalt 

emulsion showed projected creep strain under 3% 

over 30 years at 25 psi constant stress making 

them acceptable for base course.

Conclusions 

! Marshall stability showed strong posi/ve 

correla/on to LBR strength for all stabilizing 

agents. Marshall flow showed strong posi/ve 

correla/on to creep strain rate for cement and 

CSS-‐1H but weak posi/ve correla/on for SS-‐1H 

! Unconfined compression and indirect tensile 

results did not consistently correlate to LBR or 

creep strain rate

Conclusions 

! The Creep Strain Rate method of projec/ng 

creep using a logarithmic curve fit of 

experimental data between 0.01 and 7 days 

gave similar results to the Singh and Mitchell 

modeling method.

Recommenda/ons 

! Do not use lime stabiliza/on with RAP/ 

limerock blends 

! Use blends of 50% RAP/50% limerock without 

stabilizing agents for subbase course 

! Use blends of 50% RAP/50% limerock with 

asphalt emulsion or cement stabiliza/on for 

base course 

! Possibly use blends of 25% RAP/75% limerock 

without stabilizing agents for base course

Ques/ons?

Improving the Properbes of Reclaimed Asphalt Pavement for ...

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