Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 222222
Loughborough University

Centre for Innovative and Collaborative Construction Engineering


Dr Paul Edwards


Laboratory characterisation of pavement foundation materials

Project Title

Laboratory Characterisation of Pavement Foundation Materails


Scott Wilson


Prof N Dixon
Dr P R Fleming

M J Brough
R J Armitage

Director of Research:
Professor K Shiono

Research Period

2002 - 2006


Laboratory Characterisation of Pavement Foundation Materails


Traditionally highway pavement design in the UK has primarily been based on empirical design methods. Empirical methods, by definition rely on a knowledge and long-term experience of certain types of pavement material under certain conditions. The intrinsic problem with this approach is that unless the long-term experience exists the data cannot be confidently extrapolated or new factors introduced. This effectively acts as a barrier towards the use of alternative materials (including recycled/secondary aggregates and hydraulically bound mixtures). The wider use of these alternative materials is critical if government sustainable construction targets are to be met.

The adoption of analytical pavement designs (based on actual material performance rather than empirical relationships) requires suitable input design parameters to be derived for pavement foundation materials. Developments within this area of pavement foundation material characterisation (including environmental assessment/guidance) to promote innovation and the wider use of alternative materials were identified as an industry wide requirement.

Aims and Objectives

The specific aims and objectives of the project include:

• The development of material characterisation procedures to allow innovative use of bound and unbound materials primarily within the foundation layers of pavement constructions.
• Define parameters required for pavement foundation materials to allow innovative pavement constructions to be adopted via analytical design procedures.
• Develop innovative testing procedures to characterise these materials engineering behaviour.
• Specification(s) development and industry guidance for the use of these materials within pavement design.

Method and Current Status

A series of primarily government (Highways Agency and Waste Recycling Action Program) research funded projects have been undertaken to meet the EngD aims and objectives. Methodologies include literature reviews, field and laboratory testing. Other activities include participation within special interest groups (Britpave Soil Stabilisation

Task Group) and professional bodies (Institute of Civil Engineers via the East Midland Geotechnical Group).

The main project undertaken over the first period of the doctorate is the development and testing of a new mechanical laboratory test for pavement foundation materials. Details of the test development and initial results have been published in the following paper:

Edwards, J.P., Thom, N.H. and Fleming, P.R (2004). ‘

Development of a simplified test for unbound aggregates and weak hydraulically bound materials utilising the NAT’. UNBAR 2004. Other projects undertaken outside of the laboratory include the review and updating of HD35/95 (Highways Agency guidance on the conservation and the use of secondary and recycled materials). Result from this were published to promote awareness in the wide range of recycled and secondary materials acceptable for use within highway construction projects:

Edwards, J.P. (2003). ‘

Recycling and Secondary Materials in Highways Works’ Transportation Professional Journal, October 2003.

Benefits/Expected Outcomes

Potential benefits of the wider use of in-situ stabilised (bound) materials and/or alternative aggregates (recycled or secondary) within pavement designs (instead of traditional unbound primary aggregates) include:

• Reduced on/off site construction traffic.
• Reduced demands on the environment for primary aggregate abstraction.
• Reduced demands on the environment by recycling or using secondary materials (reduction in material for landfill).
• Potential for comparative benefits in pavement foundation layer performance, facilitating reductions in the overall thickness of pavement design.

The introduction of analytical pavement designs and supporting material characterisation techniques should also allow innovative designs and subsequently benefit industry and the client in terms of cost savings.
















Edwards, J.P., Thom, N.H. And Fleming, P.R., Accelerated Laboratory Based Mechanistic Testing of Unbound Materials within the Newly Developed NAT Springbox, 84th Transportation Research Board Meeting, Washington, January 2005, cd-rom, [CD-ROM].

Edwards, J.P. … et al. (2005). Testing of Unbound Materials in the Nottingham Asphalt Tester Springbox. Transportation Research Record.  Vol. 1913. Journal of the Transportation Research Board. [http://dx.doi.org/10.3141/1913-04].

Edwards, J.P. … et al. (2005). Simplified laboratory assessment of subgrade performance parameters for mechanistic design of pavement foundations. Transportation research record : journal of the Transportation Research Board, 1913, pp.77-85. [DOI:10.3141/1913-08].

Edwards, JP, Thom, NH, Fleming, PR. (2004). Development of a simplified test for unbound aggregates and weak hydraulically bound materials utilising the NAT. In Dawson, AE (ed) Proceedings of the 6th International Symposium on Pavements Unbound, Balkema, pp.3-12.

Edwards, JP, Thom, NH, Fleming, PR. (2005). Accelerated Laboratory Based Mechanistic Testing of Unbound Materials within the Newly Developed NAT Springbox. In 84th Transportation Research Board Meeting, Washington, pp.cd-rom.



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Loughborough University
LE11 3TU

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