MA/6/4/003: The use of quarry fines in hydraulically bound mixtures ...

Mineral Industry Research Organisation (MIRO) 

MA/6/4/003: The use of quarry fines in 

hydraulically bound mixtures for construction 

applications 

Technical Report

Authorised by: 

Date: 17 March 2008 

Dr Joanne Wint, Senior Consultant 

Unless otherwise stated, all photographs courtesy of Scott Wilson. 

This document has been prepared in accordance with the scope of Scott Wilson's appointment with its 

client and is subject to the terms of that appointment. It is addressed to and for the sole and 

confidential use and reliance of Scott Wilson's client. Scott Wilson accepts no liability for any use of 

this document other than by its client and only for the purposes for which it was prepared and 

provided. No person other than the client may copy (in whole or in part) use or rely on the contents of 

this document, without the prior written permission of the Company Secretary of Scott Wilson Ltd. Any 

advice, opinions, or recommendations within this document should be read and relied upon only in the 

context of the document as a whole. The contents of this document do not provide legal or tax advice 

or opinion. 

© Scott Wilson Ltd 2008

The Mineral Industry Research Organisation (MIRO) 

The use of quarry fines in HBMs for construction applications – Technical report 

EXECUTIVE SUMMARY 

This report details the laboratory research undertaken in support of the guidance document for 

the use of quarry fines in construction applications, specifically within hydraulically bound 

mixtures (HBMs). 

The work was funded by the Minerals Industry Sustainable Technologies (MIST) programme in 

accordance with Thematic Priority 4: Optimising Resource Value (quarry product application). 

A performance based approach has been adopted to evaluate the incorporation of quarry fines 

in HBMs. Five quarry dusts were sourced from locations throughout the UK, representing a 

range of lithologies and material characteristics. The methodology comprised preliminary 

classification, testing, iterative mixture design, mechanical performance and durability testing. 

The testing suites adopted were based upon the current HA specifications and design guidance. 

Due to the particle size distribution of the quarry fines, BS EN treated soil standards appear 

most appropriate for the specification of quarry fines within HBMs, covered by the following BS 

EN 14227 (2006) ‘Hydraulically bound mixtures – Specifications’: 

• Part 10: soil treated with cement (SC); 

• Part 11: soil treated with lime (SL); 

• Part 12: soil treated with slag (SS); 

• Part 13: soil treated with hydraulic road binder (SHRB); and 

• Part 14: soil treated with fly ash (SF). 

The laboratory based testing programme shows that quarry fines in HBMs offer viable 

alternatives to traditionally used primary aggregates for pavement foundations. Furthermore, the 

research illustrates that the alternative hydraulic binders are also potentially suitable. The 

mechanical performance of an HBM is dependent on the following factors: 

• Strength of the component aggregate; 

• Type and quantity of binder used; 

• Water content and material density; and 

• Curing regime and age of the test specimen. 

The durability of selected HBMs was evaluated in accordance with Series 800 of the 

Specification for Highways Works. All these mixtures proved durable under the test conditions. 

A guidance document accompanies this technical report. This provides background and 

signposts to enable users to access information and relevant industry guidance, standards and 

specification documents. 

D115551 17 March 2008 




ACKNOWLEDGEMENTS 

The work described in this research report was carried out by Scott Wilson Limited. The Project 

has been supported by: 

Bob Allen – Aggregate Industries 

Brian James – The Quarry Products Association 

David Knott – Aggregate Industries 

Gordon Dick – Aggregate Industries 

Helen Bailey – Aggregate Industries 

Nizar Ghazireh – Tarmac 

Robert Gosling – Lafarge 

Steve Mee – Lafarge 

Tony Parry – The University of Nottingham 

D115551 17 March 2008 




CONTENTS 

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

2. Project aim ....................................................................................................................... 1 

3. Project objectives ............................................................................................................. 1 

4. Background ...................................................................................................................... 1 

4.1 Hydraulically bound mixtures ........................................................................................... 1 

4.2 Types of HBM................................................................................................................... 2 

5. Methodology..................................................................................................................... 2 

5.1 Sourcing of materials ....................................................................................................... 2 

5.1.1 Binders and activators............................................................................................. 4 

5.2 Aggregate classification ................................................................................................... 4 

5.2.1 Introduction.............................................................................................................. 4 

5.2.2 Particle size distribution (PSD)................................................................................ 4 

Petrographic description ........................................................................................................ 5 

5.2.3 Atterberg limits testing ............................................................................................. 5 

5.2.4 Water absorption and particle density..................................................................... 5 

5.3 Mixture design.................................................................................................................. 6 

5.3.1 Test matrix............................................................................................................... 6 

5.4 Specimen manufacture .................................................................................................... 7 

5.5 Storage and curing........................................................................................................... 8 

5.6 Performance and durability testing................................................................................... 8 

5.6.1 Introduction.............................................................................................................. 8 

5.6.2 System One testing ................................................................................................. 9 

5.6.3 System Two testing ............................................................................................... 10 

5.6.4 Durability testing .................................................................................................... 11 

6. Results ........................................................................................................................... 12 

6.1 Dolomitic limestone ........................................................................................................ 13 

6.2 Carboniferous limestone ................................................................................................ 14 

6.3 Andesite ......................................................................................................................... 15 

6.4 Granodiorite.................................................................................................................... 16 

6.5 Sandstone ...................................................................................................................... 17 

6.6 Silt .................................................................................................................................. 18 

6.7 Summary........................................................................................................................ 19 

6.8 Durability testing............................................................................................................. 21 

7. Conclusions.................................................................................................................... 22 

8. References and bibliography ......................................................................................... 24 

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GLOSSARY 

Activator 

Material which initiates hydraulic reactions 

ASS 

Air-cooled steel slag 

BS EN 

European standard published by the British Standards Institution (BSI) 

CBGM 

Cement bound granular mixture 

CKD 

Cement kiln dust 

CEMI 

Class 42.5N Portland Cement 

CEMII 

Class 32.5N Portland Cement (blended with PFA) 

DMRB7 Design Manual for Roads and Bridges, Volume 7 

E c 

Modulus of elasticity (E) determined in compression, expressed in 

GigaPascals (GPa) 

FABM 

Fly ash bound mixture 

GBS 

Granulated blastfurnace slag 

GGBS 

Ground granulated blastfurnace slag 

HBM 

Hydraulically bound mixture 

HL 

Hydrated lime [Ca(OH) 2 ] also known as slaked hydrated lime 

Hydraulic Binder Cementing materials which harden in the presence of water 

MCHW1 Manual of Contract Documents for Highway Works Volume 1: 

specification for highway works 

MPa MegaPascal equivalent to 1 Newton per millimetre squared (1 N/mm 2 ) 

OWC 

Optimum water content 

Pozzolanic material A siliceous or siliceous and aluminous material which, by itself, 

possesses no cementitious properties but will chemically react with 

lime to produce materials with cementitious properties. 

PI 

Plasticity index 

PFA 

Pulverized-fuel ash 

R c 

Compressive strength 

R c vs 

Coefficient of volumetric stability 

R it 

Indirect tensile strength 

R c imm 

Compressive strength after immersion in water 

R t 

Tensile strength 

Series 800 

Series 800 of MCHW1 

SBM 

Slag bound mixture 

SC 

Soil cement 

SFA 

Soil treated by fly ash 

SH 

Soil treated by hydraulic binder 

SHRB 

Soil treated by hydraulic road binder 

SL 

Soil treated by lime 

SROH 

Specification for the reinstatement of openings in highways 

SS 

Soil treated by slag 

D115551 17 March 2008 




1. INTRODUCTION 

This research report has been produced by Scott Wilson Ltd for the Mineral Industry Research 

Organisation (MIRO). It presents the findings of the research undertaken in line with the project 

aim and objectives. The report gives details of the sourcing of aggregate materials and 

hydraulic binders/activators; mixture design; specimen preparation; mechanical performance; 

and durability testing. The work was undertaken over a 10 month period from May 2007 to 

February 2008. 

2. PROJECT AIM 

The aim of this project is to identify and characterise hydraulically bound mixtures (HBMs) 

incorporating quarry fines suitable for use in construction applications. The project proposal was 

in response to the sixth call for proposals and in accordance with Thematic Priority 4: Optimising 

resource value (quarry product application). 

The research will aid the development, and maximise the use, of quarry by-products in higher 

value construction applications. 

3. PROJECT OBJECTIVES 

The objectives of this project are: 

1. A review of existing studies and information sources; 

2. Laboratory research to characterise HBMs (in terms of stiffness, deformation, durability 

and mixture volumetric stability) and relate these to potential applications; and 

3. The dissemination of information to partners and interested parties throughout the 

project, and the production of a guidance document and technical report detailing the 

project findings. 

This report details the laboratory research carried out to achieve Objective 2, and discusses the 

results with reference to potential applications. 

A guidance document for use of HBMs within construction applications (specifically within 

pavement foundations) accompanies this technical report. 

4. BACKGROUND 

4.1 HYDRAULICALLY BOUND MIXTURES 

A hydraulically bound mixture (HBM) can be defined as a mixture comprising an aggregate with 

a controlled grading and one or more hydraulic binders that have been mixed together using a 

technique that produces a homogenous mixture (adapted from BS EN 14227-1: 2004). The 

definition of HBMs can also be expanded to include treated and stabilised soils, since the 

definition of a soil as taken from BS EN 14227-10 to BS EN 14227-14 is given as “natural, 

artificial or recycled material or any combination of these components”. 

Hydraulic binders include cement, fly ash (pulverised-fuel ash) and slag (a by-product of iron 

smelting). Some of the binders require an activator such as lime or steel slag. Others simply 

require the addition of sufficient water. The rate of strength gain, the ultimate strength and the 

overall performance of a HBM is dependent on its age, curing conditions and its component 

parts (comprising the binder and aggregate). 

Specifications for HBMs are covered in European harmonised standards, which were mainly 

published between 2004 and 2006. The standards for HBMs were subsequently incorporated 

into the Specification for Highways Works Manual of Contract Documents for Highways Works 

Volume 1 (MCHW1 Series 800, 2007) and pavement foundation and structural pavement 

design guidance (DMRB7, Section 2, IAN73/06, 2006 and Part 3, HD26, 2006). 

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17 March 2008 




The revised specifications for HBMs and the introduction of IAN73/06 and HD26 into pavement 

design guidance now mean that the upper structural layers of a pavement are no longer 

independent of foundation quality. The quality of the pavement foundation is incorporated into 

the pavement design by the introduction of four foundation classes based upon a composite 

stiffness and resistance to permanent deformation. HBMs offer the opportunity to construct 

foundations superior to traditional unbound granular ones. Therefore, in the context of the 

overall pavement design, HBMs have both a technical and potential economic advantage over 

their unbound counterparts. An overview of the advantages and disadvantages of using HBMs 

is given in the guidance document ‘MA/6/4/003: The use of quarry fines in hydraulically bound 

mixtures for construction applications – Guidance document’. 

4.2 TYPES OF HBM 

HBMs are classified into three groups according to the type of hydraulic binder used in the 

mixture: 

• Cement bound granular mixture (CBGM); 

• Slag bound mixture (SBM); and 

• Fly ash bound mixture (FABM). 

Treated soils are also classed as HBMs, as defined in BS EN 14227: 2004 – Parts 10 to14. 

Here, soil is defined as “natural, artificial or recycled material or any combination of these”. As in 

the case of the previous HBMs they are defined by the type of hydraulic binder used: 

• Soil cement (SC); 

• Soil treated by hydraulic binder (SH); 

• Soil treated by fly ash (SFA); 

• Soil treated by slag (SS); 

• Soil treated with hydraulic road binder (SHRB); and 

• Soil treated by lime (SL). 

The top four treated soil options (binders) were considered most suitable for inclusion within this 

research. 

5. METHODOLOGY 

5.1 SOURCING OF MATERIALS 

A range of lithologies and material types were sourced for inclusion in the project. Locations of 

the quarries are given in Figure 1. They were selected because they offer the greatest potential 

for utilisation in terms of the production volumes, and also allow assessment across a range of 

material types. 

The material types sourced from the various UK wide locations were as follows: 

• Igneous rock – both Leicestershire sites; 

• Sedimentary rock (including limestones) – County Durham, South Wales and Lancashire; 

• Washings from sand and gravel processing – Staffordshire. 

In total, five different materials were used as aggregates for the HBM mixture design and are 

shown in Figures 2 to 4. 

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Co. Durham 

Lancashire 

Staffordshire 

South 

Wales 

Leicestershire 

Figure 1: Locations of materials sourced for inclusion in the project. 

Figure 2: Andesite (left) and granodiorite (right). 

Figure 3: Dolomitic limestone (left) and carboniferous limestone (right). 

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Figure 4: Silt. 

5.1.1 Binders and activators 

The following pozzolanic binders and activators were sourced prior to design of the test matrix: 

• Hydrated lime (HL) – LIMBUX CL90-S lime was sourced from Buxton Lime Industry (BLI) 

conforms to BS EN 459-1 (2001); 

• Portland Cement (CEMI) – was sourced from BLI and conforms to BS EN 197-1 (2000), 

Class 42.5N cement; 

• Portland Cement (CEMII) – was sourced from Lafarge and conforms to BS EN 197-1 

(2000) Class 32.5N Portland cement. 

• Pulverized-fuel ash (PFA) – was sourced from Tilbury Power Station via the UK Quality Ash 

Association. The PFA was a siliceous conditioned fly ash generally compliant with BS EN 

14227-4, (2004), the exception being loss on ignition. This was reported to be in excess of 

the upper limit of 10% by mass; 

• Cement Kiln Dust (CKD) – was sourced via Lafarge from their cement plant at Westbury. 

• Ground Granulated Blast Furnace Slag (GGBS) – was sourced through the Cementitious 

Slag Makers Association (CSMA). The material was classed as GG4 (Table A.4, Appendix 

A, BS EN 14227-2: 2004), using the ‘Blaine’ fineness test (ASTM C204-07, 2007). 

5.2 AGGREGATE CLASSIFICATION 

5.2.1 Introduction 

A petrographic description was conducted on each aggregate, together with laboratory 

characterisation comprising particle size distribution (PSD), plasticity index (on material passing 

0.425 mm), particle density, and water absorption where appropriate. The PSD results were 

plotted against the BS EN HBM envelopes to assess the suitability for inclusion in a HBM. 

5.2.2 Particle size distribution (PSD) 

The particle size distribution (PSD) was assessed for each aggregate source and initially plotted 

against the grading envelope for a CBGM, SBM and FABM as given in BS EN 14227- 1 to BS 

EN 14227-3 (2004). All the materials exceed the maximum limit for material passing the 0.063 

mm sieve. Therefore, for their use to be permitted in Series 800 (MCHW1, 2007), they should 

be classed as a treated soil with the designation - SC (soil cement), SFA (soil treated by fly ash) 

or SS (soil treated by slag). The grading requirement for these materials is stated as “not less 

than 95% of the material passing a 63 mm sieve”, with which they all comply. 

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2 

4 



The PSD analysis was carried out in accordance with BS EN 933-1 (1997). The results are 

presented in Figure 5. 

100 

90 

Dolomitic 

Limestone 

80 

Mass % passing 

70 

60 

50 

40 

Carboniferous 

Limestone 

Andesite 

30 

20 

Granodiorite 

10 

0 

Sandstone 

0.063 

0.212 

0.425 

6.3 

10 

20 

31.5 

Sieve size (mm) 

Figure 5: PSD of quarry fines aggregates determined in accordance with BS EN 933-1: 

1997. 

Petrographic description 

The petrographic description of each aggregate was conducted in accordance with BS EN 932- 

3: 1997 the materials were described as: 

• DOLOMITIC LIMESTONE occurring as silty fine to coarse sand sized material with much 

fine angular gravel; 

• CARBONIFEROUS LIMESTONE occurring as a grey to light brown sand sized material 

with some fine angular gravel; 

• ANDESITE occurring as light grey silty fine to coarse sand sized material with some fine 

angular gravel; 

• GRANODIORITE occurring as pink very silty fine to coarse sand sized material with some 

fine to medium angular gavel; 

• SANDSTONE occurring a slight brown silty fine to coarse sand with some fine to medium 

angular gravel; and 

• Light orange brown SILT with some fine sand. 

5.2.3 Atterberg limits testing 

Atterberg limit testing was carried out in accordance with BS 1377-2: 1990. All the aggregates 

are classed as non-plastic. 

5.2.4 Water absorption and particle density 

The water absorption and particle density were determined in accordance with the BS EN 1097- 

6: 2000 pyknometer method for aggregate between 0.063 mm and 4 mm for all the aggregates 

except for the sandstone and silt. Testing was carried out on the 4 to 10 mm fraction of the 

sandstone. The silt was not tested due to its particle size distribution. The results are presented 

in Table 1. 

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Table 1: Water Absorption and Particle Density results (BS EN 1097-6: 2000). 

Determination 

Apparent particle density 

(ρa) 

Particle density on ovendried 

basis (ρrd) 

Particle density on a 

saturated and surface dry 

basis (ρssd) 

Unit 

Dolomitic 

Limestone 

Carboniferous 

Limestone 

Aggregate 

Andesite Granodiorite Sandstone 

Mg/m 3 2.74 2.36 2.80 2.77 2.35 

Mg/m 3 2.58 2.32 2.74 2.75 2.34 

Mg/m 3 2.64 2.34 2.76 2.75 2.34 

Water absorption (WA 24) % 2.20 0.87 0.84 0.20 0.14 

Both aspects of this test are important to determine the potential durability and performance as 

a mixture. Water absorption of an aggregate affects the durability of the parent HBM; it is the 

ingress of water into a pavement which can lead to degradation of the structure. The greater the 

particle density, the greater the density of the HBM; this can be associated with increased 

mechanical performance. 

5.3 MIXTURE DESIGN 

A number of commonly used and alternative binders such as cement kiln dust (CKD) were used 

in the mixture trials. The BS EN standards for a treated soil do not specify binder contents; 

however, the minimum binder contents are given in Series 800, these are presented in Table 2 

(taken from Table 8/10, Series 800 MCHW1, 2007). 

Table 2: Minimum binder contents as specified for stabilised soils in the Series 800 

(MCHW1, 2007). 

HBM Designation 

Minimum binder addition including activator where appropriate 

SC 3% 

SS 4%* 

SFA 6%** for dry FA or 8%** for conditioned FA 

Note: * including a minimum of 1.5% by dry mass of the mixture for powder activators (e.g. lime or 

cement) and 2.5% by dry mass of the mixture for granular activators, where permitted. Percentage 

of activator to be increased by 0.5% for ‘mix-in-plant’ using volume batching production and by 1% 

for ‘mix-in-place’ production. 

** including a minimum of 2% lime by dry mass of the mixture as activator (2.5% for ‘mix-in-plant’ 

using volume batching, 3% for ‘mix-in-place’ production). Where cement is used instead of lime, 

these percentages shall be increased by 0.5%. 

Based on the particle size distribution and the minimum binder content specified in Series 800 

(MCHW1, 2007), a minimum cement content of 3 % was adopted. 

5.3.1 Test matrix 

The aggregate and binder/activator combinations assessed in the project are given in Table 3. 

The binders selected cover a range of materials, some of which are industrial by-products. 

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Table 3: Test matrix of aggregate binder/activator combinations. 

Aggregate 

Grading 

(mm) 

No 

Binder 


CEMI CEMII PFA/HL PFA/CKD PFA/CKD/ 

HL 

CKD 

GGBS/HL 

Dolomitic 

Limestone 

0/5 - - Y Y Y Y Y - 

Carboniferous 

Limestone 

0/5 Y Y - - - - Y - 

Andesite 0/5 Y Y - Y - - Y Y 

Granodiorite 0/5 - Y Y - - - - - 

Sandstone 0/10 - Y Y - - - - - 

Silt < 0.063 - Y - - - - - Y 

5.4 SPECIMEN MANUFACTURE 

The HBM specimens were manufactured in accordance with BS EN 13286-51: 2004. Cylindrical 

specimens for System One and System Two performance testing (Section 5.2) were made 

using liners of 4 mm thick ridged plastic pipe with a nominal diameter of 102 mm. They were cut 

to a length of 204 mm, giving a height to diameter (H:D) ratio of 2:1. Specimens for volumetric 

stability testing had a H:D ratio of 1:1. 

The aggregate samples were stored in either one tonne dropsacks or metal stillages at Scott 

Wilson’s pavement test facility. Sub-sampling for each mixture was carried out using fractional 

shovelling in accordance with BS EN 932-2: 1999. For performance testing, each mix typically 

comprised ten 2:1 (H:D) specimens. The relative proportions of the HBM constituents 

(aggregate and binder) were calculated on a dry weight basis to achieve the desired percentage 

composition for the mix. 

The aggregate and binder/activator(s) were added to an electric drum mixer and blended to 

ensure a homogenous mix prior to the addition of water (to the target water content). The mixer 

was left running for five minutes to ensure complete mixing. 

The specimen liners were fitted with a collar, to prevent damage to the liner during compaction, 

then fixed into a compaction frame. The compaction hammer was supported on a frame, 

minimising manual contact during compaction, hence reducing the risk of vibration white finger 

to the operator. This method was also found to improve reproducibility between operators. The 

specimens were constructed in approximately 50 mm lifts. 

Following the placement of the loose material in the liner, care was taken to avoid any 

segregation, which has been found to result in the formation of voids around the perimeter of 

the specimen. The vibrating hammer was lowered onto the sample. Additional weights were 

then applied prior to compaction of that layer. The dead load mass of the vibrating hammer, 

shank, compaction foot and additional weights was 40 kg. The diameter of the compaction foot 

was 96 mm. The electric vibrating hammer used was compliant with BS EN 13286-4: 2003. 

Each layer was compacted for sixty seconds, measured using an electronic timer. This was 

found to be a suitable period of time to ensure compaction of the material to refusal. Prior to 

placement of each layer, the top of the previous layer was scarified to ensure interlock between 

the layers. Following compaction of the final layer, the collar was removed and the specimen 

taken out of its frame. Excess material was struck off with a straight edge and voids were filled 

with representative material. To finish the specimens, a 150 mm diameter compaction foot was 

employed to achieve full surface compaction. A steel float was then used to ensure a smooth 

level finish was achieved on the specimen ends. This additional care was undertaken to avoid 

the need to cap the ends of the specimen. The specimens were then sealed with cling film and 

tape prior to storage for curing. 

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5.5 STORAGE AND CURING 

All specimens were sealed and cured in their liners. No specimens recorded a loss of more 

than 2% mass between manufacture and immediately prior to testing. The samples were all 

stored vertically, under different conditions depending on the curing regime required. 

The following two curing regimes were adopted during the testing programme: 

• Sealed curing at 20°C or 40°C (shown in Figure 6) was undertaken in a temperature 

controlled area of the laboratory or calibrated oven, respectively; and 

• Immersed curing in temperature controlled concrete curing tanks at either 20°C or 40°C. 

The water tanks were insulated and covered in order to limit temperature fluctuations. 

Figure 6: Specimens cured at 20°C (left) and 40°C (right). 

5.6 PERFORMANCE AND DURABILITY TESTING 


The mechanical performance classification system for HBMs contained within Series 800 

(MCHW1, 2007) and European Standards (BS EN 13286-41 to 43, 2003) can be divided into 

two systems: 

• System One – based on an indirect method such as compressive strength, R c ; and 

• System Two – based on a more fundamental combination of tensile strength, R t , and 

modulus of elasticity, E c . 

The route for assessing mechanical performance in the laboratory is shown in Figure 7. 

The laboratory performance testing of HBMs in this project used both System One (R C ) and 

System Two (E C and R t ) testing methodologies. This allowed the mechanical performance of 

each HBM to be evaluated using the more traditional compressive strength test, along with the 

derivation of a foundation class from the modulus of elasticity and tensile strength (IAN73, 

2006). 

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Classification Testing 

Mechanical Testing 

System One 

System Two 

Assesses: 

Compressive strength [BS EN 13286-41: 

2003]. Specimens of a height to diameter 

(h:D) ratio of 2:1 or 1:1 are subjected to a 

uniform loading so failure occurs between 30 

and 60 seconds 

Assesses: 

Direct tensile strength (BS EN 13286-41: 

2003) or Indirect tensile strength [BS EN 

13286-42: 2003] and Modulus of Elasticity 

[BS EN 13286-43: 2003]. 

Requires specimens of a h:D ratio of 2:1 

Durability Testing 

In accordance with Series 800 

[SHW], NF P98 234-1:1992 and 

BS 812-124:1989 

If proved to be durable the HBM 

is suitable for use in a specified 

application area 

Figure 7: Route for the laboratory assessment of mechanical performance in the 

laboratory. 

5.6.2 System One testing 

In accordance with BS EN 13286-41: 2003, compressive strength testing was undertaken on 

cylinders of a 2:1 or 1:1 height to diameter ratio (H:D) (shown in Figure 8). Specimens were 

subjected to a continuous and uniform loading so that failure occurred within 30 to 60 seconds 

of the test commencing. Results outside this period were discarded. The strength datasets were 

expressed in MegaPascals (MPa). Compressive strength testing at 28 days age, after curing at 

20 or 40°C, forms the simplest system for classifying the performance of HBMs. However, 

correlations to pavement design parameters are required to predict likely performance. 

Therefore, the Highway Agency pavement foundation performance testing and design 

document (IAN73, 2006) introduced the elastic modulus test (Figure 9) to assist in determining 

a design input parameter (essentially a long term layer stiffness value), with the compressive 

strength testing being used for subsequent control and specification compliance testing. 

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Figure 8: Compressive strength testing of a 1:1 height to diameter specimen of an HBM. 

5.6.3 System Two testing 

System Two refers to mechanical characterisation of HBMs using direct (BS EN 13286-41: 

2003) or indirect tensile strength (BS EN 13286-42: 2003) and modulus of elasticity (BS EN 

13286-43: 2003). All of these tests require specimens of a minimum H:D ratio of 2:1. The exact 

minimum height to diameter ratio is a function of the maximum aggregate size and specimen 

diameter. 

Figure 9: Strain collar fitted to a 2:1 HBM specimen during modulus of elasticity testing. 

The modulus of elasticity test set up is shown in Figure 8. Strain (ε) is measured over the 

central part of the cylindrical specimen and the strain at 30% of the peak force (F r ) is recorded 

(ε 3 ). The modulus of elasticity is calculated using Equation 1. The resulting modulus of elasticity 

measurement (E C ) is sometimes referred to as a static stiffness due to the slow loading rate of 

D115551 Page 10 

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the test. Test loading is specified as a constant rate causing failure of the specimen within 30 to 

60 seconds after the commencement of the test. 

Equation 1: 

E 

c = 

1.2F 

πD 

r 

2 

ε 3 

Where: 

E c is the modulus of elasticity in compression (MPa) 

F r is the peak force (N) 

D is the specimen diameter (mm) 

ε 3 is the longitudinal strain of the specimen (at 30 % of F r ) 

The modulus of elasticity (E c ) measures the element elastic stiffness modulus (defined as the 

secant stiffness at 30% of the peak force). The layer stiffness (IAN73, 2006) is assumed to be 

10% or 20% of the element stiffness (stiffness of the test specimen), it can be approximated 

simply using: 

Equation 2: E ( GPa) = E ( GPa) × 0.2 

or 0. 1 

l 

C 

This degradation factor is based upon overseas experience (LCPPC – SETRA, 1997) and 

recent work in the UK (Chaddock and Roberts, 2006). 

The tensile strength test is designed to model the forces exerted on a pavement layer in a 

direction perpendicular to the applied load, the strength datasets are expressed in MPa. 

However, tensile strength (R t ) is difficult to determine experimentally, so is derived from the 

indirect tensile strength (R it ) using established relationships (BS EN 14227-1 to 3: 2004); 

Equation 3: R 

t 

= R 

it 

× 0.8 ( MPa) 

5.6.4 Durability testing 

Durability is currently assessed in Series 800 (MCHW1, 2007) using the procedure given in 

clause 880.4. Cylinders with a ratio of 1:1 (H:D) are prepared and cured for 14 days in air. They 

are then cured for a further 14 days immersed in water. The compressive strength of these 

immersed samples (R C imm ) is determined along with that of the control specimens (R C control ). 

The control specimens are cured for 28 days in a sealed condition. The mixture is considered to 

be durable if the following applies: 

⎛ R ⎞ 

⎜ c imm ⎟ 

Equation 4: R 

c vs 

= 

×100 ≥ 80% 

⎜ R 

⎟ 

⎝ c control ⎠ 

where: 

R c vs 

is the relative volumetric stability (assumed to be durable if ≥ 80 %) 

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6. RESULTS 

The mixture references used are based upon the nominal particle size, type and quantity of 

binder used. Table 4 gives further details of the abbreviations. 

Table 4: Explanation of mixture reference system. 

Aggregate Maximum aggreate size (mm) Abbreviation Binder Abbreviation 

Dolomitic Limestone 5 D5 CEMI C 

Carboniferous Limestone 5 C5 CEMII CC 

Andesite 5 A5 CKD K 

Granodiorite 5 G5 PFA P 

Sandstone 10 S10 HL H 

Silt - S GGBS G 

For example: 

• D5CC4 is dolomitic limestone with 4% CEMII 

• A5P10H1.5 is andesite with 10% PFA and 1.5 %HL 

• D5P10K6H2 is dolomitic limestone with 10% PFA, 6% CKD and 2% HL. 

The percentage binder and activator combinations trialled for each aggregate, are presented in 

Table 5, together with the curing regimes and report reference. 

Table 5: Curing regime for laboratory performance testing of the HBM’s trialled for each 

aggregate source. 

Aggregate 

(grading/mm) 

Dolomitic 

Limestone 

fines(0/5) 

Carboniferous 

Limestone (0/5) 

Andesite (0/5) 

Granodiorite 

(0/5) 

Sand (0/10) 

Silt (



6.1 DOLOMITIC LIMESTONE 

System One mixture testing was carried out on three HBMs: 

• CKD alone; 

• PFA with CKD as activator; and 

• PFA/CKD with HL as activator. 

All the specimens were cured at 40°C for 7 days prior to testing. The results are presented in 

Table 6. The PFA/CKD (D5P10K4) combination gave comparable results to that with the 

addition of HL (D5P10K6H2). This indicates that the pozzolanic behaviour of the PFA is 

activated by CKD. The best performing mixture was D5K10 (10% CKD only), giving an average 

compressive strength (R C ) of 5.2 MPa. 

Table 6: Results of System One testing for dolomitic limestone at 7 days age. 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 

System 1 

R C (MPa) 

(Mg/m 3 ) h/d n mean SD 

D5P10K4 10.60 2.33 2:1 5 2.51 0.33 

D5P10K6H2 10.53 2.36 2:1 5 2.29 0.10 

D5K10 10.38 2.42 2:1 5 5.22 0.62 

System Two testing was carried out on the mixtures D5CC5, D5P8H2 and D5K5. The results 

are presented in Table 7. 

Table 7: Results of System Two testing for dolomitic limestone at 28 days age. 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 

System 1 

R C (MPa) 

R t (MPa) 

System 2 

E C (GPa) 

E layer 

(MPa) 

(Mg/m 3 ) h/d n mean SD n mean SD n mean SD Mean 

D5CC5 8.88 2.48 2:1 5 7.41 0.74 4 0.84 0.03 4 9.87 3.75 1974 

D5P8H2 10.22 2.38 2:1 5 3.58 0.65 5 0.54 0.04 4 5.99 1.45 599 

D5K5 9.66 2.49 2:1 5 2.60 0.46 4 0.21 0.02 4 1.70 0.45 170 

The System One results are plotted against the foundation classes given in BS EN 14227- 

14:2006 (Figure 10). The positions of the low limit categories are the same for SC and SFA; 

therefore, D5CC5 can be plotted with D5P8H2 and D5K5. It can be seen from Figure 10 that a 

limestone and 5 % CEMII SC gives the best performing HBM (class T2). The SFA (D5P8H2) is 

also classed as a T2, while the HBM which used CKD as the hydraulic binder (D5K5) was 

classed as a T1. 

D115551 Page 13 

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10 

D5CC5 

D5P8H2 

T5 

T4 

R t (MPa) 

1 

D5K5 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 10: T class derived from System Two testing of dolomitic limestone. 

6.2 CARBONIFEROUS LIMESTONE 

The carboniferous limestone was trialled with CKD (Figure 11) and GGBS/HL (report reference 

C5K10 and C5G4H2). The specimens were cured at 20°C and 40°C respectively and tested at 

28 days. It was also assessed using 4 % CEMI at 28 days. The results are presented in Table 

8, and the T class is plotted in Figure 12. 

Figure 11: An HBM incorporating carboniferous limestone and CKD. 

Table 8: Results of System One and Two testing for Carboniferous Limestone. 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 

System 1 System 2 

R C (MPa) R t (MPa) E C (GPa) 

E layer 

(MPa) 


C5K5 7.35 2.44 2:1 5 1.75 0.30 5 0.14 0.01 4 0.67 0.15 67 

C5G4H2 6.68 2.46 2:1 5 10.21 1.17 5 1.37 0.04 4 20.34 3.88 2034 

C5C4 6.25 2.48 2:1 5 8.51 1.17 - - - - - - - 

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10 

C5G4H2 

T5 

T4 

R t (MPa) 

1 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 12: T class derived from System Two testing of dolomitic limestone. 

Only the mixture C5G4H2, designated a SS, could be plotted on the System Two chart. HBM 

C5K5 plotted outside of the limits for a System Two foundation classification and is, therefore, 

classed as a T0 by default. 

6.3 ANDESITE 

The andesite was trialled using CEMI cement at a range of binder contents, alongside testing 

with CKD, PFA/HL. Any self cementing properties were also investigated by compacting 

specimens without adding any hydraulic binder, (mixture A5) and subjecting them to durability 

testing (see Section 5.6.4). The results are presented in Table 9 and Table 10. 

Table 9: Results of System One and Two testing of andesite at 7 days age. 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 



E layer 

(MPa) 


A5K10 9.07 2.39 2:1 5 2.37 0.76 - - - - - - - 

A5C6 8.95 2.49 2:1 5 6.43 0.97 5 0.78 0.07 5 13.21 2.09 2642 

A5C7 9.25 2.49 2:1 5 6.67 0.60 5 0.84 0.08 5 12.87 6.58 2574 

A5P10H1.5* 7.69 2.40 2:1 5 6.29 0.64 - - - 4 4.00 0.55 400 

Note: * A5P10H1.5 was tested at 14 days 

Andesite trialled with CKD (mix ref A5K10) gave a mean compressive strength (R C ) of 2.37 

MPa. The mixture was cured at 40°C. This result is slightly higher than the equivalent mixture 

using carboniferous limestone (C5K R C = 1.75 MPa). 

Table 10: Results of System One and Two testing of andesite at 28 days age. 

Average System 1 System 2 

Water 

E layer 

Report 

Bulk 

Content 

R C (MPa) R t (MPa) E C (GPa) (MPa) 

Reference 

Density 

(%) 


A5C4 7.40 2.48 2:1 5 7.22 0.83 2 0.88 0.01 4 7.54 0.01 1508 

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10 

A5C4 

T5 

T4 

R t (MPa) 

1 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 13: T class derived from System Two testing of Andesite. 

Andesite trialled as SC using 4% CEMI is designated a T3 (System Two classification), as 

shown in Figure 13. 

6.4 GRANODIORITE 

The granodiorite was trialled using CEMI and CEMII cement. All the specimens were cured at 

20°C for 7 or 28 days. The results of the mixture testing are presented in Table 11 and Table 

12. 

Table 11: Results of System One and Two testing of granodiorite at 7 days. 

Average 

Bulk 

Density 


E layer 

(MPa) 

Report Water 

Reference Content 


(Mg/mm 3 ) h/d n mean SD n mean SD n mean SD Mean 

G5C4 6.19 2.45 2:1 5 7.62 0.91 - - - 5 14.66 2.99 2932 

G5C6 5.95 2.45 2:1 5 11.78 1.12 - - - 5 29.15 6.80 5830 

G5CC5 6.22 2.45 2:1 5 7.29 0.73 - - - 3 15.28 1.28 3056 

G5CC7 5.23 2.43 2:1 4 14.25 3.73 - - - 3 22.41 4.86 4482 

Table 12: Results of System One and Two testing of granodiorite at 28 days. 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 



E layer 

(MPa) 


G5C4 6.74 2.40 2:1 5 10.84 1.19 - - - 3 21.62 3.09 4324 

G5CC5 6.50 2.4 2:1 5 9.31 0.54 5 1.02 0.12 4 15.28 3.28 3056 

Mixtures G5C4 and G5CC5 both exhibited increased compressive strength when tested at 28 

days compared to 7 days. For example, the mixture incorporating 4% CEMI, the R C at 7 days = 

7.6 MPa whereas, R C at 28 days = 10.84 MPa. In general, SC’s using granodiorite perform 

relatively well. This may be attributed to the mineralogy of the component aggregate, since the 

rock from which the fines are derived is very strong; this is illustrated by the relatively high 

particle density. 

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10 

G5CC5 

T5 

R t (MPa) 

1 

T4 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 14: Foundation class derived from System Two testing of granodiorite. 

The granodiorite incorporated into a SC using 5 % CEMII plots as a T3 (Figure 14). Based on 

the results of compressive strength and modulus of elasticity testing for the other mixtures it 

would be reasonable to assume that the other HBM mixtures trialled would not plot lower than a 

T3 based on this result. 

6.5 SANDSTONE 

The sandstone was trialled with 4% CEMI and 5% CEMII. Both were cured at 20 °C and tested 

at 28 days. The results are presented in Table 13. The compressive strength of the mixtures 

was comparable (~ 5 MPa). System Two testing also gave similar results for the two mixtures. 

Table 13: Results of System One and Two testing of sandstone at 28 days age. 

Average 

Bulk 

Density 


E layer 

(MPa) 

Report Water 

Reference Content (%) 



S10C4 6.13 2.20 2:1 5 5.26 1.96 5 0.51 0.08 4 10.43 4.09 1043 

S10CC5 6.72 2.28 2:1 5 5.34 0.30 4 0.54 0.07 4 7.88 1.10 788 

The HBMs incorporating sandstone, CEMI and CEMII, both plotted as Foundation Class T1 

(Figure 15). 

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10 

S10C4 

T5 

S10CC5 

T4 

R t (MPa) 

1 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 15: T class derived from System Two testing of sandstone. 

6.6 SILT 

The silt was trialled with 4% CEMI, cured at 20°C and 4% GGBS 2% HL, cured at 40°C. Both 

were tested at 28 days. The results are presented in Error! Reference source not found. The 

slag treated material performed better than the cement treated material in both System One and 

Two testing. For System One, the SC compressive strength was 1.7 MPa, while the SS gave a 

compressive strength of 4.8 MPa. 

Table 14: Results of System Two testing of silt at 28 days age. 

Average 

Bulk 

Density 

System 1 

System 2 

E layer 

(MPa) 

Report Water 


Reference Content 

(Mg/mm 3 ) 

h/d 

n mean SD n mean SD n mean SD Mean 

SC4 15.38 2.00 2:1 4 1.65 0.53 4 0.12 0.03 3 1.29 0.62 129 

SG4H2 15.56 2.10 2:1 5 4.79 0.79 5 0.49 1.95 4 5.45 0.12 545 

Figure 16 shows a SC HBM incorporating 4% CEMI. The right hand plate shows specimens 

post indirect tensile strength testing. 

Figure 16: A soil cement incorporating silt and 4 % CEMI. 

D115551 Page 18 

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10 

SG4H2 

T5 

R t (MPa) 

1 

T4 

T3 

T2 

T1 

T0 

0.1 

1 10 100 

Ec (GPa) 

Figure 17: T class derived from System Two testing of silt. 

The System Two class derived for the mixture SG4H2 (4% GGBS and 2% HL) is a class T2 

foundation (Figure 17). The mixture SC4 (4% CEMI) does not plot on the graph and is therefore 

designated a T0. 

6.7 SUMMARY 

The HBM mixtures trialled have been classified as soil cements (SC), soil fly ash (SFA) and soil 

slags (SS). In general, for a given binder content, SC’s using CEMI cement performed better 

than those employing CEMII. The greater cement component used in CEMI over CEMII may 

account for this. Typical 28 day compressive strengths range from 1.7 MPa (SC4 – silt 4% 

CEMI) to 7.6 MPa (G5C4 – granodiorite and 4 % CEMI). System Two testing for the soil 

cements tested ranged from a T0 (SC4) to T3 (A5C4). 

Trialling of the aggregates in SFA HBMs gave 28 day compressive strengths of 3.6 MPa 

(D5P8H2 – dolomitic limestone with 8% PFA and 2% HL) to 6.3 MPa (A5P10H1.5 – andesite 

with 10% PFA and 1.5% HL). D5P8H2 gave a System Two, T2 material. 

Soil slag HBMs produced compressive strengths ranging from 4.8 MPa (SG4H2) to 10.2 MPa 

(C5G4H2 – carboniferous limestone, 4% GGBS and 2% HL). System Two classes derived for 

these HBMs were T3 and T2, respectively. 

HBMs incorporating alternative binders such as CKD gave compressive strengths from 2.4 MPa 

(A5K5 – andesite and 5% CKD) to 5.2 MPa (D5K10 – dolomitic limestone and 5% CKD cured at 

40 °C). D5K10 plots as a System Two, T2. The rate of setting using CKD as a hydraulic binder 

appears to be closer to a FABM (or SFA) and SBM (or SS) than a CBGM (or SC). However, 

further work is required to confirm this. No improvements in performance were observed when 

CKD was used in conjunction with PFA or PFA and HL. 

Compressive strengths for the HBMs trialled are summarised in Figure 18. 

D115551 Page 19 

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12 

10 

Compressive Strength R C (MPa) 

8 

6 

4 

† 

2 

0 

Soil Cement 

Soil Slag 

Soil Fly 

Ash 

Note: † tested at 14 days age. 

Figure 18: System One testing at 28 days. 

The T classes derived for the HBMs trialled under System Two testing are summarised in Table 

15. It can be seen that the best performing mixtures, in terms of System Two classes, are those 

incorporating quarry fines derived from igneous rock and used in a SC. SS HBMs (C5G4H2 and 

SG4H2) perform relatively well, giving a class T3 and T2 material respectively. A HBM 

incorporating silt and GGBS and HL gave a foundation class T2 material. 

Table 15: Summary of the T classes derived from System Two testing. 

HBM 

Mixture Reference 

System Two Class 

E layer 

(MPa) 

A5C4 T3 1508 

G5CC5 T3 3056 

D5CC5 T2 1974 

SC 

S10CC5 T1 788 

S10C4 T1 1043 

SC4 T0 129 

C5K5 T0 67 

D5K5 T1 170 

SS 

C5G4H2 T3 2034 

SG4H2 T2 545 

SFA D5P8H2 T2 599 

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6.8 DURABILITY TESTING 

Durability testing was carried out on selected aggregates using CEMI cement. Both andesite 

and carboniferous limestone were also trialled without a binder. Carboniferous limestone is 

known to contain calcium oxide (CaO) which may exhibit self-cementing properties on 

hydration. Andesite was also trialled without binder as a control, since it does not contain CaO. 

The procedure followed is specified in Clause 880.4 (Series 800 MCHW1: 2007). The mixtures 

tested are given in Table 16. The results are presented in Table 17. 

Table 16: Mixtures selected for durability testing. 

Aggregate 


% 


Curing 

Temperature 

(°C) 

Specimen 

Age (days) 

Report 

Reference 

Dolomitic 

limestone 

Andesite 

CEMI 4 20 28 D5C4 

CEMI 3 20 28 D5C3 

CEMI 4 20 28 A5C4 

- - 20 28 A5 

Granodiorite CEMI 4 20 28 G5C4 

Carboniferous 

limestone 

- - 20 28 C5 

Table 17: Results of durability testing in accordance with Series 800 (MCHW1: 2007). 

Report 

Reference 

Water 

Content 

(%) 

Average 

Bulk 

Density 

(Mg/m 3 ) 

h/d n mean SD n mean SD 

D5C4 9.74 2.53 2:1 3 6.17 1.54 3 6.76 0.44 91 

D5C3 9.21 2.51 2:1 3 6.27 0.83 3 7.82 1.04 80 

A5C4 7.40 2.48 2:1 3 6.74 0.75 3 7.42 0.83 91 

A5 7.22 2.39 2:1 

R C imm (MPa) 

R C control (MPa) 

Specimens disintegrated 

R C vs (%) 

G5C4 6.52 2.37 2:1 3 7.97 0.64 3 8.47 0.97 94 

C5 6.08 2.53 2:1 

Specimens disintegrated 

All the mixtures proved durable at relatively low additions of CEMI (3% and 4%). The mixtures 

A5 and C5 (no binder) disintegrated during the immersion stage of the test. This suggests these 

aggregates have no self cementing properties and would not be suitable for use without 

employing a hydraulic binder and or activator. 

D115551 Page 21 

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7. CONCLUSIONS 

Laboratory based research on a range of quarry fines and hydraulic binder(s) has shown that 

these materials, when used in HBMs, are viable materials for construction and engineering 

applications (MIST, 2008). 

BS EN treated soil standards appear most appropriate for the specification of quarry fines within 

HBMs (BS EN 14227:2004): 

- Part 10: soil treated with cement (SC) 

- Part 11: soil treated with lime (SL) 

- Part 12: soil treated with slag (SS) 

- Part 13: soil treated with hydraulic road binder (SHRB) 

- Part 14: soil treated with fly ash (SF) 

Mechanical performance was determined by a combination of System One (compressive 

strength) and System Two (tensile strength and elastic modulus testing). From the results 

obtained, the following conclusions are made: 

• With respect to the soil cement mixtures, the overall strength gain is very much a function 

of the aggregate type. The highest compressive strengths were achieved in HBMs 

incorporating granodiorite, followed by those incorporating andesite. In comparison, low 

strengths were achieved with silt and cement mixtures. This could be due to relatively low 

mechanical interlock between the slit particles; 

• As expected, greater strength gains can be made by increasing the cement binder content. 

The compressive strength is also dependant on the density of the specimens, which is in 

turn dependant on the water content and grading profile of the aggregate used. Greater 

mechanical interlock of aggregate particles in the HBM coupled with a relatively strong 

component aggregate results in a good performing HBM as demonstrated in the SC’s 

incorporating andesite; 

• The overall performance of a soil cement is dependent on the quantity of the cement 

addition. For a given addition of hydraulic binder, CEMI gives a greater performance over 

CEMII, However, the rate of the pozzolanic activity of the PFA contained in CEMII is slower 

than that of cement alone. Therefore, accelerated curing (elevated temperature) or 

extended curing times may demonstrate that CEMI and CEMII can give equivalent 

performance in the long term (all SC’s tested in this project were cured at 20°C). Further 

work would be needed to confirm this. 

• Of the HBMs evaluated, those which may require pre-cracking (that is, those obtaining 28 

day compressive strengths > 8 MPa) are: 

- SC’s of andesite and granodiorite with CEMI at additions of 4% and above; and 

- Carboniferous limestone with 4% GGBS and 2% HL. 

• Quarry fines incorporated into an SFA HBM also showed potential with respect to 

mechanical performance, although compressive strengths obtained were generally lower 

than those of the SC HBMs. This may be due to the further addition of fine material (PFA) to 

the mixture, which may result in a reduction in performance over the equivalent SC by 

reducing mechanical interlock between the aggregate particles. The use of CKD as a 

hydraulic binder showed promising results. Further work is needed to fully evaluate the 

likely performance characteristics of HBM’s incorporating CKD. In particular, to develop 

curing regimes which reflect likely site performance and optimisation of additions of binder, 

and possibly use of an activator. 

• Results obtained for SS HBMs (that is, mixtures C5GH and SGH) are surprising in that the 

performance is generally better both for System One and Two performance testing. HBMs 

of T class T3 and T2 were obtained including use with silt. The equivalent SC (silt) plotted 

as a T0. 

D115551 Page 22 

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Durability was determined in accordance with clause 880.4 of Series 800 (MCHW1, 2007). The 

following conclusions can be made based on the results obtained; 

• The mixtures would be suitable for incorporation into road foundations, even at the 

minimum binder contents trialled. 

• Further investigation would be required to determine the effect of curing temperature on 

mixtures using the alternative binder combinations (CKD, PFA/CKD, PFA/CKD/HL and so 

on) 

• Durability testing should be carried out on a wider range of HBMs . 

The guidance document that accompanies this technical report contains details on the use of 

HBMs in construction applications, specifically within pavement foundation layer construction. 

The guidance builds upon the findings of the laboratory based study and relates it to existing 

industry specification and historical use of HBMs. This guidance document is aimed at 

producers, buyers, contractors, designers and clients, and assesses the materials against 

industry recognised standards and specifications in order to disseminate the findings of this 

research project into practical and economically viable construction applications. 

D115551 Page 23 

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8. REFERENCES AND BIBLIOGRAPHY 

ASTM C204-07:2007. ASTM C204-07 Standard Test Methods for Fineness of Hydraulic 

Cement by Air-Permeability Apparatus. ASTM. 

BS 812-124 (1989). Method for determination of frost heave. London: British Standards 

Institution. 

BS EN 197-1:2001. Cement. Composition, specifications and conformity criteria for common 

cements. London: British Standards Institution. 

BS EN 459-1:2001. Building lime. Definitions, specifications and conformity criteria. London: 

British Standards Institution. 

BS EN 932-1:1997. Tests for general properties of aggregates. Methods for sampling. London: 


BS EN 932-2: 1999. Tests for general properties of aggregates. Methods for reducing laboratory 

samples. London: British Standards Institution. 

BS EN 932-3:1997 Tests for general properties of aggregates. Procedure and terminology for 

simplified petrographic description (AMD 14865). London: British Standards Institution. 

BS EN 933-1:1997. Tests for geometrical properties of aggregates. Determination of particle 

size distribution - Sieving method (AMD 15907). London: British Standards Institution. 

BS EN 1097-6:2000. Tests for mechanical and physical properties of aggregates. Determination 

of particle density and water absorption (AMD Corrigendum 14306) (AMD 15908). London: 


BS 1377-2:1990. Soils for civil engineering purposes. Classification tests (AMD 9027). London: 


BS EN 13286-4: 2003. Unbound and hydraulically bound mixtures. Test methods for laboratory 

reference density and water content - Vibrating hammer. London: British Standards Institution. 

BS EN 13286-41:2003. Unbound and hydraulically bound mixtures. Test method for 

determination of the compressive strength of hydraulically bound mixtures. London: British 

Standards Institution. 

BS EN 13286-42: 2003. Unbound and hydraulically bound mixtures. Test method for 

determination of the indirect tensile strength of hydraulically bound mixtures. London: British 


BS EN 13286-43:2003. Unbound and hydraulically bound mixtures. Test method for the 

determination of the modulus of elasticity of hydraulically bound mixtures. London: British 


BS EN 13286-51:2004. Unbound and hydraulically bound mixtures. Method for the manufacture 

of test specimens of hydraulically bound mixtures using vibrating hammer compaction. London: 


BS EN 14227-1: 2004. Hydraulically bound mixtures - Specifications. Cement bound granular 

mixtures. London: British Standards Institution. 

BS EN 14227-2:2004. Hydraulically bound mixtures. Specifications. Slag bound mixtures. 

London: British Standards Institution. 

BS EN 14227-3:2004. Hydraulically bound mixtures. Specifications. Fly ash bound mixtures. 


D115551 Page 24 

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BS EN 14227-10:2006. Hydraulically bound mixtures. Specifications. Soil treated by cement. 


BS EN 14227-11: 2006. Unbound and hydraulically bound mixtures. Specifications. Soil treated 

by lime. London: British Standards Institution. 

BS EN 14227-12:2006. Hydraulically bound mixtures. Specifications. Soil treated by slag. 


BS EN 14227-13:2006. Hydraulically bound mixtures. Specifications. Soil treated by hydraulic 

road binder. London: British Standards Institution. 

BS EN 14227-14:2006. Hydraulically bound mixtures. Specifications. Soil treated by fly ash. 


B Chaddock and C Roberts (2006). Road foundation design for major UK highways. Project 

report PPR 127. TRL. 

Highways Agency. (2001). HD26: Pavement design and maintenance. Pavement design 

andconstruction. Pavement design. Design Manual for Roads and Bridges: Volume 7 Section 

2Part 3. London: The Stationery Office. 

Highways Agency. (2006). Interim Advice Note. IAN 73/06: Design Guide for Road Pavements 

(Draft HD25). London: The Stationery Office 

Highways Agency. (2007). Manual of Contract Document for Highways Works: Volume 1, 

Specification for Highways Works. London: The Stationary Office. 

LCPC-SETRA (1997). French design manual for pavement structures. Translation of the 

December 1994. French version of the technical guide. Published by Laboratoire Central des 

Ponts et Chaussees (LCPC) and Service d’Etudes Techniques des Routes et Autoroutes 

(SETRA). 

NF P98 234 – (1992). Tests related to pavements. Freezing behaviour of materials treated with 

hydraulic binders – Part 1: Freeze thaw test of stabilized gravel or sand. France: 

NormeFrancaise Homologue, ANFOR. 

D115551 Page 25 

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Mineral Industry Research Organisation (MIRO) 

MA/6/4/003: The use of quarry fines in 

hydraulically bound mixtures for construction 

applications 

Guidance document

Written by; 

Caroline Walters 

Assistant Scientist, Scott Wilson 

Paul Edwards 

Principal Engineer, Scott Wilson 

Tony Parry 

Associate Professor, The University of Nottingham 

Authorised by: 

Rebecca Hooper; Associate 

Date: 07 March 2008 

Unless otherwise stated, all photographs courtesy of Scott Wilson. 

This document has been prepared in accordance with the scope of Scott Wilson's appointment with its 

client and is subject to the terms of that appointment. It is addressed to and for the sole and 

confidential use and reliance of Scott Wilson's client. Scott Wilson accepts no liability for any use of 

this document other than by its client and only for the purposes for which it was prepared and 

provided. No person other than the client may copy (in whole or in part) use or rely on the contents of 

this document, without the prior written permission of the Company Secretary of Scott Wilson Ltd. Any 

advice, opinions, or recommendations within this document should be read and relied upon only in the 

context of the document as a whole. The contents of this document do not provide legal or tax advice 

or opinion. 



The use of quarry fines in HBMs for construction applications – Guidance document 

EXECUTIVE SUMMARY 

This guidance document covers the use of quarry fines in hydraulically bound mixtures (HBMs) 

for construction applications, specifically within pavement foundation layers. 

This work was funded by the Minerals Industry Sustainable Technologies (MIST) programme in 

accordance with Thematic Priority 4: Optimising Resource Value (quarry product application). 

A performance based approach is used throughout this guide, with reference made to the 

project technical report and associated findings which accompanies this guidance document. 

This document outlines the route for assessing the suitability of quarry fines (and other 

aggregate materials) for inclusion in HBMs for specified applications, with a range of traditional 

and alternative binders. Findings from laboratory research are discussed and guidance given 

on the design methods, and the performance and durability testing procedures necessary to 

ensure that durability requirements are met. Both environmental and non-environmental factors 

that could have an impact on the long-term performance of a HBM are also considered. 

The document addresses the following areas; 

• The materials and applications of HBMs 

• Specification and compliance 

• Design of a HBM for durability 

• Application into pavement construction 

• Trial sections 

This guide does not provide specific guidance on issues such as layer thickness design and site 

specific considerations. Instead, it provides the signposts and background for readers to be 

able to access this information and relevant industry guidance, standards and specification 

documents. The guide concentrates on the application of HBMs into pavement foundation 

construction, with reference made to other applications areas where relevant. 

D115551 07 March 2008 




ACKNOWLEDGEMENTS 

The work described in this research report was carried out by Scott Wilson Limited. The Project 

has been supported by: 

Bob Allen – Aggregate Industries 

Brian James – The Quarry Products Association 

David Knott – Aggregate Industries 

Gordon Dick – Aggregate Industries 

Helen Bailey – Aggregate Industries 

Nizar Ghazireh – Tarmac 

Robert Gosling – Lafarge 

Steve Mee – Lafarge 

Tony Parry – The University of Nottingham 

D115551 07 March 2008 




CONTENTS 

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

1.1 Purpose of the guide ........................................................................................................ 1 

1.2 Scope of the guide ........................................................................................................... 1 

1.3 Key definitions .................................................................................................................. 1 

2. Hydraulically bound mixtures ........................................................................................... 2 

2.1 What are HBMs? .............................................................................................................. 2 

2.1.1 Considerations......................................................................................................... 3 

2.1.2 The binders.............................................................................................................. 3 

2.1.3 HBM – Aggregates .................................................................................................. 4 

2.1.4 HBM – Applications ................................................................................................. 4 

2.2 Quarry fines...................................................................................................................... 5 

2.2.1 Indicative suitability.................................................................................................. 7 

3. Specification and compliance........................................................................................... 8 

3.1 Factors to be considered.................................................................................................. 8 

3.1.1 Short-term performance – Workability and trafficking ............................................. 8 

3.1.2 Long-term performance – Durability and degradation............................................. 8 

3.1.3 Economic viability .................................................................................................... 8 

4. Design of HBMs for durability........................................................................................... 9 

4.1 Factors affecting durability ............................................................................................... 9 

4.1.1 Environmental factors.............................................................................................. 9 

4.1.2 Non-environmental factors ...................................................................................... 9 

4.1.3 Drainage .................................................................................................................. 9 

4.2 Assessing durability ....................................................................................................... 10 

4.2.1 Classification testing.............................................................................................. 11 

4.3 Performance and mechanical testing............................................................................. 12 

4.3.1 Introduction............................................................................................................ 12 

4.3.2 System One testing ............................................................................................... 13 

4.3.3 System Two testing ............................................................................................... 13 

4.4 Durability testing............................................................................................................. 14 

5. Design and construction considerations ........................................................................ 16 

5.1 Laying of the HBM.......................................................................................................... 16 

5.2 On-site production control .............................................................................................. 18 

5.3 Cracking and pre-cracking ............................................................................................. 18 

5.4 Trial sections .................................................................................................................. 19 

6. Summary........................................................................................................................ 20 

7. Sources of further information........................................................................................ 21 

7.1 Useful websites .............................................................................................................. 23 

8. References and bibliography ......................................................................................... 23 

D115551 07 March 2008 




GLOSSARY 

Activator 

Material which initiates hydraulic reactions 

ASS 

Air-cooled Steel Slag 

BS EN 

European Standard published by the British Standards Institution (BSI) 

CBGM 

Cement Bound Granular Mixture 

CKD 

Cement Kiln Dust 

CEM I 

Class 42.5N Portland Cement 

CEM II 

Class 32.5N Portland Cement (incorporating PFA) 

DMRB7 

Design Manual for Roads and Bridges, Volume 7: Specification for 

Highways Works 

E c 

Modulus of elasticity (E) determined in compression, expressed in 

GigaPascals (GPa) 

FABM 

Fly Ash Bound Mixture 

GBS 

Granulated Blastfurnace Slag 

GGBS 

Ground Granulated Blastfurnace Slag 

HBM 

Hydraulically Bound Mixture 

HL 

Hydrated lime [Ca(OH) 2 ] also known as slaked hydrated lime 

Hydraulic Binder Cementing materials which harden in the presence of water 

MCHW1 Manual of Contract Documents for Highway Works, Volume 1: 

Specification for Highway Works 

MPa MegaPascal equivalent to 1 Newton per millimetre squared (1 N/mm 2 ) 

OWC 

Optimum Water Content 

QL 

Quicklime 

PI 

Plasticity Index 

PFA 

Pulverized-Fuel Ash 

R c 

Compressive strength 

R c vs 

Coefficient of volumetric stability 

R it 

Indirect tensile strength 

R c imm 

Compressive strength after immersion in water 

R t 

Tensile strength 

Series 800 

Series 800 of MCHW1 

SBM 

Slag Bound Mixture 

SHW 

Specification for Highways Works 

SROH 

Specification for the Reinstatement of Openings in Highways 

D115551 07 March 2008 




1. INTRODUCTION 

1.1 PURPOSE OF THE GUIDE 

This document provides guidance on the application of quarry fines into hydraulically bound 

mixtures (HBMs) for construction applications, specifically within pavement foundation layers. 

This guidance document covers a range of potential materials, their scope for use, methods for 

assessing their characteristics and performance, and the general considerations and factors 

affecting their potential use. 

Reference is given throughout the document to the findings from research and laboratory 

assessment carried out as part of this work. This work involved the development of HBM 

specifications containing a range of quarry fines and various binders, and subsequent 

mechanical testing to assess their performance and suitability for use in HBMs. Full data and 

discussion of the findings can be found in the technical report which accompanies this guidance 

document [MIST, 2008]. 

1.2 SCOPE OF THE GUIDE 

The use of quarry fines within HBMs provides decision makers with an increased range of 

options for mixture design and provides an alterative, and potentially large, market application 

for these quarry ‘by-products’. The use of these materials has potential benefits on both 

engineering and sustainability terms, and this document provides guidance on how these 

benefits can readily be achieved. Guidance is given to producers, buyers, contractors, 

designers and clients on the use of quarry fines in HBMs for construction applications, with 

specific attention being paid to use in pavement foundation layers. It is based on a review of 

existing literature and on extensive laboratory research carried out as part of this project. 

All guidance in this document meets industry recognised standards and specifications and 

reference is given to the relevant documents for full details of the design methods and 

specifications where stated. 

1.3 KEY DEFINITIONS 

Unless otherwise specified, the term ‘quarry fines’ is used throughout this report instead of 

‘dusts’, ‘by-products’, ‘wastes’, or ‘rockdusts’. 

• Quarry fines – Materials typically produced as a by-product of the blasting, crushing and 

screening processes at quarries. Fines are classed as aggregate passing the 4 mm sieve 

for use in concrete and related materials, and passing the 2 mm sieve for use in asphalt [BS 

EN 13043: 2002]. Anything larger than 4 mm is classed as coarse aggregate [BS EN 13043: 

2002] 

• Hydraulically bound mixtures (HBMs) – A mixture of aggregate or soil, with a hydraulic 

binder and, where appropriate, secondary constituents, which is designed to attain a 

structural integrity [BS EN 14227: 2004]. 

• Hydraulic binders – These are materials that can be used to bind aggregate or soil particles 

together. Some require an activator, such as lime, while others simply require the addition of 

sufficient water for activation. Hydraulic binders include cement, fly ash and slag. 

D115551 Page 1 

07 March 2008 




2. HYDRAULICALLY BOUND MIXTURES 

2.1 WHAT ARE HBMS? 

HBMs set and harden by hydraulic reaction and their classification is based on the material 

treated (the type of aggregate or soil), the binder(s) used, the process by which it has been 

mixed, and the end performance requirements. By combining an aggregate with hydraulic 

binder(s), the strength, durability and volume stability of the material being treated can be 

tailored to specific requirements. 

The use of HBMs in construction applications can have a number of advantages and some 

disadvantages; 

Advantages 

• HBMs provide the opportunity for a greater number of secondary and recycled materials to 

be used within higher value applications, rather than as unbound granular fill. 

• HBMs reduce the demand on other construction materials, such as Type 1 aggregate. 

• HBMs can be produced to the specific strength and/or stiffness required by a particular 

engineering project. 

• HBMs can be used in a cold state and they gain strength and/or stiffness over a period of 

time. This slow curing time allows for a longer time frame for laying, compacting and (if 

required) pre-cracking. 

• The high strength and stiffness values offered by HBMs allow for a reduction in the thickness 

of overlying layers in a pavement. This can help to reduce the cost of the overall project. 

• HBMs allow for the re-use of excavated or demolition materials on-site. This reduces the 

need to import materials and it reduces the transport costs and distances of material that 

would have needed to have been brought to or taken away from site. 

• The mixtures can be produced either in situ or ex situ and can be designed to have long term 

shelf lives. Plant required for laying and compaction are similar to those used for other 

materials, such as unbound mixtures and bituminous bound mixtures. 

• HBMs can help organisations improve the sustainability of their projects and help them to 

meet or exceed client requirements for ‘green’ procurement [WRAP, 2005]. 

• The use of HBMs can have an energy saving effect on a project overall [ETSU, 1997]. 

Disadvantages 

• Higher stiffness values offered by some HBMs may lead to cracking and deformation (for 

example, reflective cracking in the overlying asphalt layers). This can me mitigated by precracking. 

• The materials require compaction. 

• The use of a roller compactor or padfoot may be required during laying and compacting of 

the fine grained material. This may increase the cost and/or time required for construction. 

D115551 Page 2 

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2.1.1 Considerations 

There are a number of key considerations that need to be taken into account when assessing if 

the use of HBMs (including those containing quarry fines) is appropriate. These include; 

• Material resource efficiency – will the HBM effectively replace or be superior to other 

traditionally bound or unbound materials? Will the potential requirement of high binder 

contents be an issue? 

• Economics – Will the use of HBMs help to reduce or maintain the cost of the project, when 

compared to traditional materials? 

• Haulage – Are the materials available locally? 

outweigh the cost savings made elsewhere? 

Will the costs associated with haulage 

• Technical – HBMs offer a superior foundation layer and so reduce the requirement for a 

thick surface layer. What binder content is required for this and what are the required 

compaction techniques? 

2.1.2 The binders 

HBMs generally comprise an aggregate and binder(s), sometimes with an activator to activate 

the hydraulic reaction. Typically, HBMs are classed according to their binder type, with the most 

common being; 

• Cement Bound Granular Mixture (CBGM) – bound using Portland cement 

• Fly Ash Bound Mixture (FABM) – bound using fly ash (or pulverized fuel ash (PFA)) from 

coal burning power stations 

• Slag Bound Mixture (SBM) – bound using granulated blastfurnace slag (GBS), an industrial 

by-product 

HBMs are aggregate and binder mixtures that set and harden in the presence of water. Some 

binders only require the addition of a sufficient amount of water to ‘activate’ the hydraulic 

reaction, and harden, whereas others require an additional activator such as lime to start the 

process. 

The speed at which this process occurs largely depends upon the binder used, the curing 

conditions and age. Typically, HBMs with cement as the binder (minimum of 3% content) can 

be classed as ‘quick hydraulic’ (QH), as they harden quickly. Whereas those with other binders, 

such as lime/PFA or lime/GBS, are classed as ‘slow hydraulic’ (SH), as they set and harden 

more slowly [Merrill et al, 2004]. 

The main binders and activators found and used within the UK are shown in Table 1. 

D115551 Page 3 

07 March 2008 




Table 1: Traditional and alternative binders used in HBMs 

Material Availability Binder Activator 

Portland Cement (PC) 

Yes Yes 

Pulverized Fuel Ash (PFA) 

Granulated Blastfurnace 

Slag (GBS) 

Ground Granulated 

Blastfurnace Slag (GGBS) 

Quicklime (QL) 

Hydrated Lime (HL) 

Gypsum 

Steel Slag 

Cement Kiln Dust (CKD) 

Paper Waste 

Red Gypsum 

By-product Lime 

Traditional Binders 

These binders are available and 

used widely in the UK and are 

covered by the appropriate BS EN 

standards and specifications for 

HBMs. 

Alternative Binders 

These binders are not as widely 

used and available in the UK and 

are not covered to the same extent 

by the appropriate BS EN 

standards and specifications for 

HBMs. 

Yes 

Yes 

Yes 

No 

No 

Yes 

Yes 

Yes 

Yes 

Yes 

No 

No 

No 

No 

Yes 

Yes 

Yes 

Yes 

Yes 

Not known 

No 

Yes 

2.1.3 HBM – Aggregates 

Aggregates for application into HBMs can be crushed or uncrushed and should comply with BS 

EN 13242: 2002. The aggregate can be naturally occurring, recycled or manufactured, or any 

combination of these. HBM properties depend mainly on the properties of the aggregate and 

the interaction between the aggregate and the binder(s), which has to be considered during 

HBM design. 

The suitability of an aggregate for application into a particular HBM is based upon the grading 

requirements specified in the relevant BS EN standard. It is also important to understand the 

characteristics and behaviour of the particular aggregate so as to be able to design mixtures 

that are suitable for their purpose. These issues are discussed further in Sections 3, 4 and 5. 

Materials also need to be assessed on a source and application specific basis. HD35 within the 

Highways Agency’s Design Manual for Roads and Bridges, Volume 7 (DMRB) [Highways 

Agency, 2001] provides advice on the use of a range of primary, secondary and recycled 

materials into HBMs, for pavement base and subbase applications. These materials include; 

blastfurnace slag, pulverized fuel ash, china clay sand, incinerator bottom ash aggregate, slate 

and spent oil shale, and many more. 

2.1.4 HBM – Applications 

HBMs have historically been used in construction applications in countries such as France, 

Holland and Germany, and to a lesser, but growing extent, within the UK. Since the introduction 

of harmonised European Standards and their adoption into the Manual of Contract Documents 

for Highways Works (MCHW), the scope for the use of HBMs has increased. HBMs are now 

increasingly being used for the construction of working platforms, liners, flood defences, trench 

reinstatement, erosion protection, major and minor roads, paved areas and heavy duty paving 

[WRAP, 2005]. 

The key application areas for HBMs include; 

D115551 Page 4 

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• Trench Reinstatement - The Specification for the Reinstatement of Openings in Highways 

(SROH) [Highways Authorities and Utilities Committee, 2002] permits several types of 

hydraulically bound mixtures for use in trench reinstatement. Confidence in the mixture’s 

performance and its suitability for application into reinstatement projects, is typically 

determined by its Compressive Strength (Rc), which gives an indication of mechanical 

performance. 

• Pavement Construction - The pavement design guidance associated with the DMRB 

[Highways Agency, 2001] permits a performance specification route for the design of 

pavement foundations. This provides details of the performance measurement of materials, 

and design values, and includes an indicative guide to the hierarchy of materials, according 

to performance. Series 800 of the Specification for Highways Works (SHW) [Highways 

Agency, 2007] is based upon European harmonised standards (BS ENs) for HBMs and 

stabilised soils for pavement subbase and base applications. Within pavement foundation 

guidance, it has been recognised that the potentially superior performance of HBM layers, 

when compared to traditionally used unbound materials, can now be factored into the overall 

pavement design and thus, allows for reductions in the thickness and strength of overlying 

layers [Highways Agency, 2006]. 

Figure 1: A HBM being compacted into a pavement foundation layer 

• Working Platforms - HBMs are commonly used in the construction of working platforms. 

Here, the HBM used provides a stable and durable temporary working surface from which 

machinery, such as piling rigs and cranes, can operate. Working platforms are required 

where the natural ground conditions are unsuitable for the safe operation of construction 

plant. The working platform may be incorporated into the permanent design if drainage, the 

stress and load applied and regularity of use, maintenance and rehabilitation are considered 

during the design stage. This can reduce overall costs significantly [Kennedy, 2006]. 

• Harbours and Flood Defences – HBMs can be applied as earthworks and liners and can 

act as protective barriers when placed in layers to construct an embankment. 

2.2 QUARRY FINES 

Quarry fines typically consist of a mixture of coarse and fine sized aggregate particles, plus a 

clay/silt fraction (fines). These aggregate fines, in accordance with the BS EN 13242: 2002, are 

classed as less than 4 mm in size for use in aggregate applications such as concrete, and less 

than 2 mm in size for use in asphalt. However, particularly within quarry operations, the term 

‘fines’ is often used to define all undersized material resulting from the blasting and crushing 

processes [Manning, 2004]. 

The British Geological Survey [2006] estimates that there are around 41 million tonnes of fine 

material produced by quarrying annually in the UK. This has increased over recent years due to 

changes in the demands and specifications for aggregates, resulting in changes to crushing and 

D115551 Page 5 

07 March 2008 




processing techniques. Currently, much of this material is stockpiled and the main applications 

to date have tended to be low value and low performance, such as in bulk fill and capping 

[British Geological Society, 2006]. 

Figure 2: Stockpiled quarry fines 

In the UK, there is considerable variability in quarry fines, both locally and nationally. This is 

dependent on lithology and the crushing, screening and processing techniques applied. The 

range of quarry fines available in the UK are summarised in Table 2. Although not quarry fines, 

fine aggregate and fines from the production of Recycled Aggregates are included for 

completeness. 

Table 2: Quarry fines types found in the UK 

Lithologies Example Types Production 

Sedimentary rock 

Dolomitic Limestone 

Carboniferous Limestone 

Sandstone 

Gritstone 

Igneous rock 

Granite 

Diorite 

Andesite 

From the blasting, crushing 

and screening processes at 

quarries 

From the blasting, crushing 

and screening processes at 

quarries 

Recycled aggregate Various/mixed Recovered construction, 

demolition and excavation 

waste (CDEW) 

Superficial deposits Silt/clay Recovered from sand and 

gravel extraction processes 

As HBMs are bound materials, they must possess strong aggregate interlock and/or a strong 

binder in order to be sufficiently durable, dependent on the specified performance requirements. 

Quarry fines are essentially a fine graded material with a general absence of coarse aggregate 

particles, so the desired strong aggregate interlock is likely to be missing. Therefore, in an 

unbound form, fines lack the ability to provide significant structural strength and stability. The 

lack of a strong aggregate interlock will also impact on the strength of the bound form. 

Therefore, issues such as ensuring that sufficient compaction is achieved need extra attention 

during the design stage (see Section 3). 

By incorporating the fines with a hydraulic binder, the lack of potential aggregate interlock is 

overcome and material strength and stiffness can be designed effectively. Additionally, by 

using a finer aggregate, issues such as segregation during transportation from quarry to site are 

reduced. The finer material can also make compaction easier and can reduce the HBM’s 

susceptibility to penetration by water. 

D115551 Page 6 

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2.2.1 Indicative suitability 

As part of the research project, a range of quarry fines and hydraulic binders were sourced and 

assessed for suitability for application into HBMs for pavement foundation construction. Quarry 

fines materials were sourced to represent a range of lithologies and material types and were 

expected to produce HBMs with a range of performance and durability characteristics. Details 

of the research project are reported in the project technical report [MIST, 2008]. 

A variety of HBMs were designed and durability and mechanical performance testing was 

conducted. 

Indicative strength values have been obtained from this testing and are shown in Table 3. All 

Rc values are for 2:1 height to diameter specimens tested at 28-days age. 

Table 3: Typical compressive strength (Rc) results for tested HBM specimens 


Generic Quarry Fine 

Lithologies 

4 to 6 % CEM I 4 to 6 % CEM II PFA* CKD* GGBS* 

Dolomitic Limestone 5 - 8 MPa 7 - 8 MPa 2 - 3 MPa 2 - 3 MPa 

Carboniferous Limestone 1 - 2 MPa 10 - 12 MPa 

Andesite 6 - 9 MPa 5 - 7 MPa 

Grandodiorite 7 - 12 MPa 7 - 10 MPa 

Sandstone 5 - 7 MPa 5 - 7 MPa 

Silt (



3. SPECIFICATION AND COMPLIANCE 

3.1 FACTORS TO BE CONSIDERED 

The development of a HBM design is an iterative process based on ongoing mixture design and 

laboratory testing in order to optimise performance and applicability into real-life settings. 

Assessment of the aggregate and binder mix, optimising the grading and establishing the 

minimum binder content are crucial to achieving a durable material suitable for use. 

3.1.1 Short-term performance – Workability and trafficking 

Pavement construction is subject to both relevant BS EN standards and specifications and the 

Manual of Contract Documents for Highways Works (MCHW), which draws upon these relevant 

BS EN standards and specifies that the structure must fulfil its role while also being durable and 

long-lasting [Highways Agency, 2007]. HBMs tend to cure and harden slowly (specifically noncement 

bound materials), therefore, allowing for a long period of workability. Their strength gain 

is also typically slow and can provide the opportunity for re-working shortly after being laid, if 

necessary [Kennedy, 2006]. 

Even though HBMs tend to require more time to achieve full strength, it is possible for the 

trafficking of the newly laid surface to begin immediately, without the need for a lengthy curing 

period. This depends upon the cohesive properties of the aggregate and binder mix and it is 

important that a mixture design established to allow for immediate trafficking must also ensure 

that there is no detrimental effect on the long-term strength gain and traffickability of the 

pavement. 

3.1.2 Long-term performance – Durability and degradation 

The role of the pavement foundation is to distribute the applied vehicle loads to the underlying 

subgrade, without causing distress to the overlying layers. During the life of a pavement, the 

foundation layer has to be able to withstand a large number of repeated loads from traffic. In 

addition to this, it is also likely to experience forms of environmental degradation, such as the 

ingress of water and temperature fluctuations. It is therefore essential that the foundation can 

withstand degradation so that excessive deformation does not occur, which can lead to rutting 

or reflective cracking and erosion in the surface layers. 

3.1.3 Economic viability 

The economic viability of using HBMs in any construction project needs to be investigated prior 

to any decisions being made relating to material selection and mixture design. Issues such as 

the required binder content and expected manufacture and compacting techniques need to be 

taken into account. In addition, material availability and the associated transport costs need to 

be taken into consideration and weighed up against alternative material solutions. 

HBMs offer a range of potential cost savings for construction projects. These include; 

• The opportunity to reduce the demand for primary materials as they allow for the greater use 

of secondary and recycled materials. If available locally, this can also help to reduce costs 

associated with transportation. 

• The typically higher stiffness values offered by HBMs compared to unbound materials, when 

used in the foundation layers of a pavement, can allow for a reduction in the thickness of the 

overlying pavement layers. This can have a cost saving impact on the overall project. This 

is particularly relevant where quarry fines are applied within HBMs due to the high stiffness 

values that they can provide. 

The typically longer working and shelf-life than traditional materials means that they can be 

easier to lay and compact. 

D115551 Page 8 

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4. DESIGN OF HBMS FOR DURABILITY 

4.1 FACTORS AFFECTING DURABILITY 

The factors that affect HBM durability can be divided into those attributed to environmental 

conditions, such as temperature, water or other deleterious substances, and those associated 

with the material components of the HBM itself. If the durability of the HBM is inadequate, these 

factors can result in shortened in-service life spans, increased maintenance requirements, or, 

ultimately, failure of the pavement and costly remedial works. 

4.1.1 Environmental factors 

The key factors that affect the durability of a HBM are environmental and chemical. 

Environmental considerations include temperature extremes and changes, and the presence of 

water. Chemical considerations include exposure to deleterious substances or substances that 

may lead to expansive reactions. Dimensional changes to a HBM layer of a pavement can 

disrupt the overall structure and/or result in reduced performance of the layer itself. Specific 

causes of dimensional change can include; 

• Thermal expansion/contraction – caused by excessive heat or cold 

• Drying shrinkage – can be caused when a material is laid ‘wet’ and then dried during 

compaction; this is usually more associated with concrete than with HBMs 

• Frost-heave – when the material expands due to frost and then shrinks when the frost 

disappears 

• Freeze-thaw – when free water in the material weakens the structure during freeze-thaw 

• Expansive reactions caused by excesses of damaging chemicals in the environment 

4.1.2 Non-environmental factors 

HBMs are only as good as their component parts and a mixture design should establish the 

optimum balance of binder, aggregate and water required to produce a suitable HBM for the 

intended use. In addition to the environmental and chemical factors, there are a number of nonenvironmental 

factors that have an impact on the durability of a HBM and should therefore be 

factored into the design stage (see relevant documents in Section 7), as shown in Table 4. 

Table 4: Non-environmental factors affecting the durability of a HBM 

Aggregate Factors Binder Factors Mixture Factors 

Quality and content of fines Curing rates Grading 

Particle density Workability Binder type(s) and content 

Water absorption Mechanical performance Compaction (including density 

and air voids) 

Resistance to fragmentation Water requirements Stiffness 

Sulfate content Chemical content Resistance to permanent 

deformation 

Stability 

Potential for cracking and the 

healing of cracks 

Permeability (both element 

and layer) 

4.1.3 Drainage 

Surface and subsoil drainage must be adequate to allow for the durability of a laid HBM to be 

maintained. Without adequate drainage the life-span and trafficking ability of the pavement will 

be restricted. This is particularly important during periods of high rainfall when the water table 

will be high [Britpave, 2007]. 

D115551 Page 9 

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4.2 ASSESSING DURABILITY 

The appropriate tests and requirements for determining the durability of a HBM are set out in 

Figure 4. The mixture design of a HBM is an iterative process based on specific and ongoing 

laboratory testing involving the assessment of both the sourced aggregate and the bound 

mixture as a whole. Through this iterative process, optimisation of performance can be achieved 

through grading analysis and establishing the optimum water content (OWC) and minimum 

binder(s) content. 

Once an aggregate and binder(s) have been sourced, classification testing must be carried out 

to determine the physical properties of the aggregate and identify where potential problems may 

lie if they were to be incorporated into a HBM, for example, adverse chemical reactions. 

Subsequent mixture design should take into account both short and long-term performance 

considerations and should involve the optimisation of grading and binder content as a result. 

Comprehensive assessment of the mechanical performance of the mixture is required to 

compare the HBM against the specified performance criteria. Subsequent assessment to 

identify the durability of the particular mixture design should also be conducted. Figure 3 

outlines the procedure for this assessment [WRAP, 2008]. 

Aggregate selection 


Grading 

Plasticity 

Water Absorption 

Organics 

Sulphate/Sulphide 

Mixture Design 

Binder Selection 

Grading Optimisation 

Production and Construction 

Quality Control 

No 

Mechanical Performance 

Testing 

No 

Does it meet the 

performance criteria? 

Yes 

Will it be used within the 

depth of frost penetration? 

Yes 

No 

Evaluate the mechanical performance in 

relation to exposure 

Evaluate Volumetric 

Stability 

Carry out 3+ month 

immersion testing 

Yes 

Are there any long-term 

chemical reactions that 

could affect volumetric 

stability? 

No 

Carry out 28 + day 

immersion testing 

Is Rc > 80% of 

original value? 

Yes 

The Mixture is 

Durable 

No 

Does it display adequate 

freeze thaw/frost heave 

resistance? 

Yes 

Figure 3. The procedure for testing the durability of a HBM [WRAP, 2008] 

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4.2.1 Classification testing 

Classification testing determines the physical properties of aggregates and their potential 

suitability and performance if they are to be included in a HBM. Grading of the material is 

carried out in order to identify whether it is well-graded; i.e. it should have a good distribution of 

particle sizes from finest to coarsest, allow for efficient compaction by forming a matrix without 

voids, and achieve the required level of durability when placed in a HBM. 

Grading must be carried out prior to any mixture design being developed, in accordance with 

BS EN 933-1:1997. Grading envelopes for CBGMs, FABMs and SBMs have been developed to 

provide guidance to producers, designers and specifiers [BS EN 14227: 2004]. These 

envelopes are used to assess whether or not an aggregate is suitable for its application by 

plotting the mass of material that passes each sieve size against the envelopes. Optimisation 

of the grading can be subsequently carried out to achieve this, often by adding other size 

fractions of the same aggregate or other materials. This ensures that the aggregate interlock is 

maximised and that a minimum number of voids are present in the final HBM. 

In general, grading envelopes are narrower and more restrictive for higher performance 

applications, such as in pavement foundation layers, compared to general fill. Figure 4 shows 

the CBGM envelopes. Envelope A covers materials that are typically fine grained and are able 

to be suitably compacted. When an aggregate plotting within this envelope is used in a CBGM, 

the mixture is referred to as a CBGMA. Envelope B covers only well-graded coarser aggregate 

that has limited fines content. Similarly, a mixture containing this type of aggregate is referred 

to as a CBGMB 

In general, quarry fines fall within Envelope A, or above. Above the limits of Envelope A, the 

HBMs are classed as treated soils [BS EN 14227-10 to 14: 2006]. 

100 

90 

80 

70 

Envelope A 

60 

Mass % 

passing 

50 

40 

Envelope B 

30 

20 

10 

0 

0.063 

0.212 

0.425 

2 

4 

6.3 

10 

20 

31.5 

Sieve size (mm) 

Figure 4: The grading envelope for a HBM (specifically a CBGM). BS EN 14227-1: 2006. 

The suitability of an aggregate for use in a HBM also depends on its capacity for compaction, 

which is determined by assessing the dry density and optimum water content (OWC) of the 

material [BS EN 13286-1 to 5: 2003]. These factors influence the resulting strength and 

stiffness values when the material is manufactured into a HBM. 

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4.3 PERFORMANCE AND MECHANICAL TESTING 


Mechanical durability testing evaluates whether or not the HBM has the potential to withstand 

long-term deleterious conditions and maintain stability and the required level of performance. 

The mechanical performance classification system for HBMs contained within Series 800 

[MCHW1, 2007] and European Standards [BS EN 13286-41 to 43: 2003] can be divided into 

two systems: 

• System One – based on an indirect method such as compressive strength, R c , and 

• System Two – based on a more fundamental combination of tensile strength, R t , and 

modulus of elasticity, E c . 

Figure 5 shows the route for assessing the mechanical performance of a HBM in the laboratory. 


Mechanical Testing 

System One 

System Two 

Assesses: 

Compressive strength [BS EN 13286-41: 

2003]. Specimens of a height to diameter 

(H:D) ratio of 2:1 are subjected to a uniform 

loading so failure occurs between 30 and 60 

seconds 

Assesses: 

Direct tensile strength (BS EN 13286-41: 

2003) or Indirect tensile strength [BS EN 

13286-42: 2003] and Modulus of Elasticity 

[BS EN 13286-43: 2003]. 

Requires specimens of a H:D ratio of 2:1 

Durability Testing 

In accordance with Series 800 

[SHW], NF P98 234-1:1992 and 

BS 812-124:1989 

If proved to be durable the HBM 

is suitable for use in a specified 

application area 

Figure 5: Routes for assessing the mechanical performance of a HBM (System One and 

System Two) 

The preparation and testing of samples should be carried out in a way that reflects expected 

real-life conditions, such as, timescale, temperature and materials. 

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4.3.2 System One testing 

A compressive strength value (System One classification) is often used as the basis for generic 

guidance. Care should be taken in relating strength gains, mixture design, material and 

application specific properties to the use of any generic guidance values as the overall 

performance of a HBM is dependant on many factors which cannot be accounted for in such 

generic values. 

Figure 6: Compressive strength testing of a 1:1 height to diameter specimen of HBM 

4.3.3 System Two testing 

The tensile strength test is designed to model the forces exerted on a pavement layer in a 

direction perpendicular to the applied load, the strength datasets are expressed in MegaPascals 

(MPa). However, tensile strength (R t ) is difficult to determine experimentally, so is derived from 

the indirect tensile strength (R it ) using established relationships [BS EN 14227-1 to 3: 2004]; 

Rt = Rit 

× 

0.8 ( MPa) 

The elastic modulus E c (also known as static stiffness) measures the element’s elastic stiffness 

modulus (defined as the secant stiffness at 30% of the peak force). The specimen is fitted with a 

collar (Figure 7) that measures the amount of specimen compression, in millimetres, during the 

application of the load to the top of the specimen. The results are expressed in GigaPascals 

(GPa). As the layer stiffness (El) is assumed to be 20% of the element stiffness (stiffness of the 

test specimen), it can be approximated simply using: 

E ( GPa) 

= E ( GPa) 

× 0.2 

l 

C 

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Figure 7: Strain collar fitted to a 2:1 HBM specimen during modulus of elasticity testing 

4.4 DURABILITY TESTING 

HBMs that exhibit compressive strengths in excess of 2 to 2.5 N/mm² are classed as bound 

materials, and are therefore, superior to unbound materials [Kennedy, 2006]. However, in 

recent years, durability recommendations for lower strength HBMs have emerged and these 

incorporate new methods of durability assessment. 

Durability is currently assessed in Series 800 of the Specification for Highways Works (SHW) 

[Highways Agency, 2007] using the procedure given in clause 880.4. Specimens with a H:D of 

1:1 are prepared and cured for 14 days in air. They are then cured for a further 14 days 

immersed in water. The compressive strength of these immersed samples (R c imm ) is determined 

along with that of control specimens (R c control ) cured for 28 days in air only. The mixture is 

classified as durable if the following applies; 

R 

c vs 

⎛ R 

= ⎜ 

⎝ Rc 

c imm 

control 

⎞ 

⎟ ×100 ≥ 80% 

⎠ 

where: 

R is the relative volumetric stability (assumed to be durable if ≥ 80%) 

c vs 

The durability of a HBM should also be evaluated with regard to issues such as resistance to 

frost heave and freeze thaw. The duration of these tests should relate to the assessed potential 

for the material to be susceptible to long-term deleterious reactions. The strength of the 

aggregate within a HBM helps to determine its susceptibility to the weathering influences of the 

freeze-thaw process and the material’s potential to lose or gain strength over time. 

Table 5 summarises the durability testing procedures for HBMs. 

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Table 5: HBM mixture durability testing procedures 

Durability Test Standards Procedure Applicability 

1:1 sealed specimens are cured 

This is a required test 

for 14 days in air then immersed in 

that must be carried 

water for 14 days at 20°C for 

Volumetric SHW Series 

out on all HBMs to be 

CBGMs and 40°C for FABMs and 

stability 800, 2007 

applied within 

SBMs. The resulting compressive 

pavement 

strength must be at least 80% of 

construction. 

the strength of control specimens. 

Freeze thaw 

Frost heave 

NF P98 234-1: 

1992 

BS 812-124: 

1989 

2:1 specimens are cured for 28 

days then soaked for 24 hours 

before being sealed. The 

specimens are then subjected to a 

cycle of air temperatures between 

-10°C and +10°C. The resulting 

compressive strength must be at 

least 80% of the average strength 

of the control specimens. 

2:1 specimens are cured for 28 

days and then subjected to a 

range of temperatures from -7.5°C 

to +4°C whilst being partially 

immersed in water. Over 96 hours 

the linear expansion of the 

samples must be



5. DESIGN AND CONSTRUCTION CONSIDERATIONS 

Pavement construction is subject to both relevant BS EN standards and the Specification for 

Highways Works (SHW), which specify that the structure must fulfil its role while also being 

durable and long-lasting. Details of the procedures to be followed when constructing a HBM are 

given in Series 800 of the SHW [Highways Agency, 2007]. 

The Highways Agency’s Interim Advice Note IAN 73/06 [Highways Agency, 2006] provides 

guidance on the design of road pavement foundations and will eventually replace the existing 

requirements set out in HD 25/94 [Highways Agency, 1994a]. New foundation classes are to be 

presented in two forms, these are, ‘performance designs’ and ‘restricted designs’. 

• Performance designs – allow a wider use of the materials but require testing of the built 

pavement foundation in order to assess whether the design requirements are met. Stiffness 

is used as a measure of support offered by the foundation layer and it must meet specified 

target values. The foundation of a pavement is categorised into one of four categories 

based on stiffness which, when assessed alongside the California Bearing Ratio (CBR) of 

the subgrade, gives the minimum layer thickness for the foundation. Reference should be 

made to IAN 73/06 [Highways Agency, 2006] for the full design process. 

• Restricted designs – these are typically applied to smaller schemes where material options 

and performance assessment methods may be limited. These designs are conservative and 

are limited to unbound mixtures or CBGMs, which allow for a level of uncertainty in design 

and construction. 

The requirements for HBM specifications for use within pavement foundation layers are 

specified in the Series 800 of the SHW [Highways Agency, 2007], and in associated Notes for 

Guidance [Highways Agency, 2007b], which relate to the relevant and current harmonised 

European Standards. 

There is this degree of uncertainty regarding the suitability of the fines, relating to their grading, 

so a laboratory test to simulate trafficking would be required. This is known as the IBI 

(immediate bearing index) test [Kennedy, 2006]. The IBI test is carried out at the mixture 

design stage and is essential for those materials that appear not to be conclusively well-graded 

and those where mechanical interlock may be reduced due to, for example, smaller aggregate 

particles. The process is simple and effective and full details on the test method and suggested 

IBI values are found in Britpave’s guidance BP/14 [2005]. 

This guide does not set out to provide a design guide for pavement layers using HBMs. For full 

details of the procedures to be carried out when constructing, laying and compacting, it is 

recommended that the relevant Highways Agency specifications are consulted (see Section 7). 

Full details on layer thickness and layer design should also be based upon these documents. 

5.1 LAYING OF THE HBM 

HBM construction is versatile in terms of plant and materials and HBMs can be produced by 

either ex situ or in situ methods; 

• Ex situ – The aggregate or soil are mixed with the hydraulic binder(s) in a stationary mixing 

plant before being placed and compacted. The plant used for these activities are the same 

that are used for traditional pavement materials, such as bituminous bound and unbound 

materials. 

• In situ – The aggregate or soil are mixed with the hydraulic binder(s) in-place using plant 

such as rotavators, before being compacted. The main benefit of this approach is that 

existing site material can be used on site, rather than having to import materials to site. 

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The construction period of a HBM denotes the time that it remains workable at a given 

temperature. For example, the construction period for cement is 35°C hours, Therefore, a 

CBGM would be workable for one hour at 35°C, or five hours at 7°C. 

The construction period for a HBM varies depending upon the type of binder used and also the 

presence of water. Table 6 details the indicative construction periods for HBMs containing 

different hydraulic binders. 

Table 6: Typical construction periods for HBMs (adapted from Series 800) [Highways 

Agency, 2007] 


Construction Period in °C hours (for example, cement 

bound HBMs would be workable for one hour at 35°C, 

or five hours at 7°C etc) 

Cement alone 

Fly ash and/or GGBS and then 

cement 

Fly ash activated by lime/gypsum 

(mix-in-plant) 

GGBS and lime 

Fly ash and lime 

Lime alone 

GBS and lime (mix-in-plant) 

GBS activated by air-cooled steel 

slag (ASS) (mix-in-plant) 

Other combinations 

35°C hours 

35°C hours from the addition of cement 

70°C hours from the addition of lime/gypsum 

200°C hours from the addition of GGBS 

800°C hours from the addition of fly ash 

1200°C hours 

1200°C hours from the addition of GBS 

3000°C hours from the addition GBS 

The workability period at 20°C is determined in accordance 

with BS EN 13286-45: 2003 

The placement of HBMs should be avoided in cold weather, specifically below 3°C. This is due 

to the risk of frost and the potential for layer degradation. 

Aggregates for use in HBMs should always be stored in a clean, dry and secure environment in 

order to prevent excessive degradation of the material or a significant change in the water 

content between mixing and application. 

The HBM layer is laid and compacted and the resulting average bulk density of the layer should 

be no less than 95% of the average bulk density of the preceding laboratory specimens. 

Compaction of the layer should be carried out by a typical vibrating or pneumatic-tyred roller. 

Figure 8: HBM being laid and compacted using conventional plant 

The compacted HBM layer should not be allowed to dry out before the overlying layer(s) are 

laid. To prevent this from occurring, a curing membrane can be applied to maintain an 

appropriate level of moisture within the layer. Compaction should also be carried out at 

optimum water content (OWC) to achieve maximum density [Kennedy, 2006]. 

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The application of quarry fines within HBMs requires specific attention during the laying and 

compaction process. Predominantly fine material may lead to coarse aggregate particles 

becoming segregated and ‘floating’ to the surface of the mixture. As a result, compaction may 

benefit from the use of a Sheepsfoot Roller or a Padfoot to mix the HBM during the process. 

Their use can help promote a strong aggregate interlock between the fines and any existing 

coarser particles, which can also help to reduce susceptibility to frost heave and permanent 

deformation. 

Typically, HBMs can be open to trafficking immediately, provided that the IBI value, grading and 

aggregate are appropriate. If any of these factors are insufficient, immediate trafficking should 

be avoided for a period of one week (longer in cooler weather). 

5.2 ON-SITE PRODUCTION CONTROL 

Production control should be carried out continuously during the construction of a HBM layer 

within a pavement. It is vital that uniformity is ensured throughout the construction process and 

that aspects such as the OWC and grading and binder content are monitored. The water 

content must be monitored and adjusted where necessary to avoid the mixture becoming too 

wet or drying out too quickly. 

If in situ methods of HBM construction are used, the rate of binder spread should be monitored. 

This can be done using a tray to catch the binder as a spreader passes over it and then the 

volume of binder caught being weighed to assess the rate and conformity of binder spread. 

If ex situ methods of HBM construction are used, the rate of feed of the HBM component 

materials should be monitored. This is to ensure that there is no change to the grading, binder 

and activator additions or water content of the HBM mix, and that there is uniformity in the rate 

of feed. 

5.3 CRACKING AND PRE-CRACKING 

A key issue in pavement design and construction is the likelihood of reflective cracking 

occurring. This is when cracks develop in the foundation layers as a result of excessive loading 

or from environmental or non-environmental factors. These cracks can then migrate into the 

surface layers and lead to rutting and surface failure. When this happens, the whole pavement 

can fail and rehabilitation or reconstruction is required [Adaska and Luhr, 2004]. 

To prevent this from occurring, induced cracking, or pre-cracking, of the HBM foundation layer 

can be carried out. Induced cracking is required if the unconfined compressive strength of a 

HBM exceeds 8 MPa, as detailed in Series 800 of the SHW [Highways Agency, 2007]. Induced 

cracking is carried out with cracks being made at specified distances apart, and with a sand and 

bitumen material then being inserted into the grooves prior to final compaction (see Figure 9). 

In order for this practice to be successful, the HBM must not be allowed to dry before the 

overlying layer is laid and so a membrane can be applied to maintain moisture within the layer. 

Figure 9: Induced cracking being carried out on a HBM subbase layer containing quarry 

fines 

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5.4 TRIAL SECTIONS 

Trial sections are recommended to test traffickability prior to a full-scale project being carried 

out. This allows HBM specifications to be assessed on a site-by-site basis and for immediate 

and existing environmental and non-environmental influences to be taken into account. 

An assessment of the ability of a HBM to withstand early trafficking should be determined in 

order to evaluate the potential risk of rutting and permanent deformation of the foundation layer, 

leading to the eventual failure of the pavement. Trial sections also allow for the assessment of 

the mixture when it is laid in large volumes and compacted using plant, rather than the scale 

encountered in the laboratory. On-site trial application means that issues such as traffic 

loading, water content, water pressure and variations in temperature and surface gradient can 

be taken into account. 

Following the laying of a demonstration site, extensive laboratory testing and on-site testing 

should be carried out to test for compliance with specific application standards and 

specifications [Kennedy, 2006]. Representative samples from the full length of the laid HBM 

layer should be taken at regular intervals prior to final compaction and these should then 

undergo laboratory testing to System One and System Two (see Section 4.3). All sampling and 

testing should be carried out to the relevant BS EN standards. 

On-site verification of the stiffness of the pavement can be essential, particularly when 

previously un-trialled HBMs have been used. Two methods for the determination of surface 

stiffness are (i) using a falling weight deflectometer (FWD) or (ii) using a lightweight 

deflectometer (LWD) (Figure 10). These processes measure the surface modulus and can be 

carried out easily and cause no disruption or damage to the pavement structure. The results 

from carrying out these assessments indicate the support being offered by the foundation layers 

to the pavement structure as a whole. 

Figure 10: LWD testing being carried out on a pavement to assess the surface modulus 

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6. SUMMARY 

This guidance document provides information for producers, buyers, contractors, designers and 

clients to increase confidence in the use of quarry fines in HBMs for construction applications, 

specifically in pavement foundation layer construction. It provides information on the materials 

available, indicative characteristics and performance parameters. From the guidance it can be 

seen that; 

• Laboratory research on a range of quarry fines and hydraulic binder(s) has shown that these 

materials, when used in HBMs, are viable alternatives for construction and engineering 

applications [MIST, 2008]. 

• BS EN treated soil standards appear most appropriate for the specification of quarry fines 

within HBMs [BS EN 14227: 2004]: 

- Part 10: soil treated with cement (SC) 

- Part 11: soil treated with lime (SL) 

- Part 12: soil treated with slag (SS) 

- Part 13: soil treated with hydraulic road binder (covering proprietary products and recycling 

processes) 

- Part 14: soil treated with fly ash (SF) 

• HBMs can be appropriately designed to provide a required strength/stiffness. They offer the 

potential for either rapid strength gain, in the case of cement treated materials, or at a slower 

rate, when other binders are used, such as slag and fly ash. 

• The use of quarry fines within HBMs in the foundation layer of a pavement may lead to 

overall cost savings. HBMs provide a stiffer base than foundations constructed using 

standard materials and techniques, thus the overlying asphalt layers do not need to be as 

thick, reducing the other material costs. This whole structure and its life-cycle cost is an 

important issue to consider when assessing the suitability of applying HBMs within the 

foundation layer. 

• The introduction of European harmonised standards for, and developments in the 

specification, testing and design of pavement foundations, means that HBMs can be 

economically competitive when compared to historic unbound materials, such as Type 1. 

This rise in competitiveness, accompanied with an increase in research and material 

understanding, will assist in a growth in the use of quarry fines in the aggregates market. 

• The application of quarry fines within HBMs has the potential for increasing the sustainability 

of construction projects as it reduces the quantity of these materials stored in stockpiles and 

increases the value of the material in terms of potential application areas. 

By using the performance approach to assessing the suitability of materials, this guidance 

document provides users with the confidence to consider the application of quarry fines within 

HBMs. Mechanical and durability testing has shown that the trialled mixtures are viable for 

application into road foundations, when assessed in line with current provisions, standards and 

specifications. 

Attention should always be paid to the most recent European Standards and Highways Agency 

specifications and requirements. Assessment on a site specific basis should be carried out 

prior to any material being applied in a real-life setting. This can be done through the use of 

mixture trials and site trafficking trials. The durability requirements of a HBM should always be 

addressed in relation to the environmental and non-environmental factors that could have an 

impact on the performance of the material during its design life. 

For more detailed information on the laboratory trials carried out as part of this project, please 

refer to the project technical report which accompanies this guidance document [MIST, 2008]. 

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7. SOURCES OF FURTHER INFORMATION 

Reference should be made to the following sources of information; 

Title 

BS EN 14227: 2004 

Unbound and hydraulically bound mixtures – 

Specifications 

• Part 1: Cement bound granular mixtures (CBGM) 

• Part 2: Slag bound mixtures (SBM) 

• Part 3: Fly ash bound mixtures (FABM) 

• Part 4: Fly ash (FA) for hydraulically bound mixtures 

• Part 5: Hydraulic road binder bound mixtures 

(HRBBM) 

• Part 10: Soil treated by cement (SC) 

• Part 11: Soil treated by lime (SL) 

• Part 12: Soil treated by slag (SS) 

• Part 13: Soil treated by hydraulic road binder (SHBB) 

• Part 14: Soil treated by fly ash (SFA) 

BS EN 13242: 2002 

Aggregates for unbound and hydraulically bound 

mixtures for use in civil engineering work and road 

construction 

BS EN 13286: 2003 

Unbound and hydraulically bound mixtures. Test 

methods. 

• Part 1: Test methods for laboratory reference 

density and water content – Introduction, general 

requirements and sampling 

• Part 2: Test methods for the determination of the 

laboratory reference density and water content – 

Proctor compaction 


density and water content – Vibrocompression with 

controlled parameters 


density and water content – Vibrating hammer 


density and water content – Vibrating table 

• Part 7: Cyclic load triaxial test for unbound mixtures 

• Part 40: Test method for determination of the direct 

tensile strength of hydraulically bound mixtures 

• Part 41: Test method for determination of the 

compressive tensile strength of hydraulically bound 

mixtures 

• Part 42: Test method for the determination of the 

indirect tensile strength of hydraulically bound 



modulus of elasticity of hydraulically bound 


Content 

Specifies the types, constituents 

and associated performance 

classes of a range of 

aggregates and soils treated 

with a range of different 

hydraulic binder types and 

contents. 

Includes the use of primary, 

secondary and recycled 

materials in HBMS. It includes 

the mechanical, physical and 

chemical test methods, and the 

associated limiting values. 

MCHW series 500, 600, 700, 

800 and 1000 are based on this 

standard. 

Details the test methods for 

assessing the characteristics, 

physical and mechanical 

properties, and durability of 

unbound and hydraulically 

bound mixtures. 

D115551 Page 21 

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alpha coefficient of vitrified blastfurnace slag 


workability period of hydraulically bound mixtures 


moisture condition value 

• Part 47: Test method for the determination of 

California Bearing Ratio, immediate bearing index 

and linear swelling 


degree of pulverisation 

• Part 49: Accelerated swelling test for soil treated by 

lime and/or hydraulic binder 

• Part 50: Method for the manufacture of test 

specimens of hydraulically bound mixtures using 

Proctor equipment or vibrating table compaction 



vibrating hammer compaction 



vibrocompression 



axial compression 

ETSU General Information Report 49 – Energy 

minimisation in road construction and maintenance 

Interim Advice Note 73/06 – Design guidance for road 

pavement foundations (Draft HD25) 

The Manual of Contract Documents for Highways Works 

(MCHW) – Series 500, 600, 700, 800 and 1000 

TRL Report 248 – Stabilised subbases in road foundations: 

structural assessment and benefits 

Chaddock and Roberts. PPR 127: 3/302_069 – Road 

foundation design for major UK highways 

NF P98 234-1 (1992) - Tests related to pavements. Freezing 

behaviour of materials treated with hydraulic binders – Part 

1: Freeze thaw test of stabilized gravel or sand. 

Britpave BP/14 – The immediate trafficking of cementbound 

materials 

Discusses the energy benefits 

of using HBMs in road 

construction. 

Guidance for the design and 

construction of road pavement 

foundations. 

The standards and 

specifications that all Highways 

Agency highways pavements 

must meet. 

A structural comparison of 

unbound and stabilised 

subbases and it provides 

guidance on thickness design 

and specification. 

Specification guidance on the 

design of flexible, rigid and 

composite pavements, it 

provides foundation designs for 

the four foundation classes. 

The procedure for carrying out 

freeze-thaw testing on HBM 

samples. 

Guidance on assessing the 

immediate bearing index (IBI) of 

HBMs at the mixture design 

stage. 

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7.1 USEFUL WEBSITES 

www.aggregate.com – Aggregate Industries 

www.aggregain.co.uk – The AggRegain Specifier Tool (designed, developed and hosted by 

WRAP) 

www.berr.gov.uk – Department for Business Enterprise and Regulatory Reform 

www.bre.co.uk – Building Research Establishment 

www.cement.org - The Portland Cement Association 

www.ciria.org – Construction Industry Research and Information Association 

www.concretecentre.com – The Concrete Centre 

www.goodquarry.com – Part of the University of Leeds 

www.highways.gov.uk – The Highways Agency 

www.lafarge.com – The Lafarge Group 

www.miro.co.uk – The Mineral Industry Research Organisation 

www.mi-st.org.uk – The Mineral Industry Sustainable Technology Programme 

www.qpa.org – The Quarry Products Association 

www.standardsforhighways.co.uk – Standards for Highways 

www.tarmac.co.uk - Tarmac 

www.trl.co.uk – Transport Research Laboratory 

www.viridis.co.uk – Part of TRL. Concerned with creating value from waste 

www.wrap.org.uk – The Waste & Resources Action Programme 

8. REFERENCES AND BIBLIOGRAPHY 

Adaska, W.S. and Luhr, D.R. (2004). Control of reflective cracking in cement stabilized 

pavements. 5 th Annual RILEM Conference. Limoges: RILEM. Available online at: 

http://www.cement.org/pavements/cracking.pdf [Accessed 02/08/08]. 

British Geological Survey. (2006). Primary Aggregates Reserves in England 1990 – 2004. 

Nottingham: The British Geological Survey 

Britpave. (2004). Stabilised soils: as subbase or base for roads and other pavements. Surrey: 

Britpave. 

Britpave. (2005). BP/14 – The immediate trafficking of cement-bound materials. Technical 

report. Surrey: Britpave. 

Britpave. (2007). HBM and stabilisation - 2: The design and specification of residential and 

commercial road pavements. Surrey: Britpave. 

BS 812-124 (1989). 

Institution. 

Method for determination of frost heave. London: British Standards 

BS EN 933-1 (1997). Tests for geometrical properties of aggregates. Determination of particle 

size distribution – Sieving method. London: British Standards Institution. 

BS EN 14227 (2004). Unbound and hydraulically bound mixtures – Specifications. London: 


BS EN 13242 (2002). Aggregates for unbound and hydraulically bound mixtures for use in civil 

engineering work and road construction. London: British Standards Institution. 

BS EN 13286 (2003). Unbound and hydraulically bound mixtures. Test methods. London: 


D115551 Page 23 

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Chaddock, B. and Roberts, C. (2006). PPR 127 3/302_069: Road foundation design for major 

UK highways. Wokingham: TRL Limited. 

ETSU. (1997). ETSU General Information Report 49: Energy minimisation in road construction 

and maintenance. Oxon: ETSU. 

Highways Agency. (1994a). HD25: Pavement design and maintenance. Pavement design and 

construction. Foundations. Design Manual for Roads and Bridges: Volume 7 Section 2 Part 2. 

London: The Stationery Office. 

Highways Agency. (1994b). HD35: Pavement design and maintenance. Conservation and the 

use of secondary and recycled materials. Design Manual for Roads and Bridges: Volume 7 

Section 1 Part 2. London: The Stationery Office. 

Highways Agency. (2001). HD26: Pavement design and maintenance. Pavement design and 

construction. Pavement design. Design Manual for Roads and Bridges: Volume 7 Section 2 

Part 3. London: The Stationery Office. 

Highways Agency. (2006). Interim Advice Note. IAN 73/06: Design Guide for Road Pavements 

(Draft HD25). London: The Stationery Office 

Highways Agency. (2007). Manual of Contract Document for Highways Works: Volume 1 

(MCHW1), Specification for Highways Works. London: The Stationary Office. 

Highways Agency (2007b). Manual of Contract Documents for Highways Works: Volume 2. 

Notes for Guidance. London: The Stationary Office. 

Highways Authorities and Utilities Committee. (2002). Specification for the Reinstatement of 

Openings in Highways: Second Edition. London: DfT. 

Kennedy, J. (2006). Hydraulically-Bound Mixtures for Pavements: Performance, behaviour, 

materials, mixture design, construction and control testing. Surrey: The Concrete Centre. 

Manning, D. (2004). MIRO – Final Report: Exploitation and use of quarry fines. Solihull: MIRO. 

Available online at: http://www.mineralsolutions.co.uk/mist/mist2.pdf [Accessed 03/10/08]. 

Merrill, D., Nunn, M and Carswell, I. (2004). A guide to the use and specification of cold 

recycled materials for the maintenance of road pavements. TRL Report TRL 611. Wokingham: 

TRL Limited. 

MIST, (2008). The use of quarry fines in HBMs for construction applications: Technical Report 

Available online at: http://www.mi-st.org.uk/section_e.htm 

NF P98 234 – (1992). Tests related to pavements. Freezing behaviour of materials treated 

with hydraulic binders – Part 1: Freeze thaw test of stabilized gravel or sand. France: Norme 

Francaise Homologue, ANFOR. 

TRL. (2007). Hydraulically bound mixtures incorporating recycled and secondary aggregates. 

Banbury: WRAP. 

WRAP. (2005). Promoting the use of applications incorporating recycled and secondary 

aggregates in hydraulically bound materials. Banbury: WRAP. 

WRAP. (2008). Development of Durability Tests for Hydraulically Bound Mixtures – 

unpublished report. Banbury: WRAP. 

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