Chapter 7: Use of Coal Combustion Products for Road Construction


Peter Heeley, Heeley's Consulting
Justin Moss, Roads and Maritime Services
Joanne Portella, Engineered Material Solutions
Michael Van Koverdan, Engineered Material Solutions
Roy Butcher, Engineered Material Solutions


The purpose of this chapter is to present information on the use of coal combustion products (CCPs), fly ash (FA) and furnace bottom ash (FBA), in road construction. Topics discussed include the properties of fly ash and furnace bottom ash and their use in road pavements including stabilisation in concrete and as sub bases.

This chapter is mainly directed to designers, specifiers and users of road materials, and provides the most up-to-date information available so that the use of road materials incorporating CCPs may be considered on an informed basis. References are also provided to enable the reader to obtain more detailed information about specific products and their relationship to current specifications and work practices.

The chapter aims to provide information on good practice in design and construction. However, the recommendations contained in the chapter should only be used by appropriately qualified professionals who can apply the appropriate specifications and design standards.


  1. 7.1 Overview
    1. 7.1.1 Introduction
    2. 7.1.2 Background and history
  2. 7.2 Properties of CCPs for Road Construction
    1. 7.2.1 Fly ash
    2. 7.2.2 Furnace bottom ash
  3. 7.3 Fly Ash as a Stabilised Base Material
    1. 7.3.1 Technology status
    2. 7.3.2 Design of cement-stabilised fly ash pavements
    3. 7.3.3 Field performance of fly ash pavements
    4. 7.3.4 Recommended construction practice
  4. 7.4 Furnace Bottom Ash as a Pavement Material
    1. 7.4.1 Technology status
    2. 7.4.2 Stabilised furnace bottom ash as a base or sub base
    3. 7.4.3 Effect of adding lime to furnace bottom ash
    4. 7.4.4 Effect of curing time
    5. 7.4.5 Effect of recompaction
    6. 7.4.6 Comparative performance
    7. 7.4.7 Recommended construction practice
  5. 7.5 Use of CCPs in Binders for Road Stabilisation
    1. 7.5.1 Technology status
    2. 7.5.2 Deep lift in situ recycling
    3. 7.5.3 Typical mixing and spreading operations
    4. 7.5.4 Stabilisation of marginal gravels
    5. 7.5.5 Heavily bound base materials
  6. 7.6 Use of Fly Ash and Cement as a Binder
    1. 7.6.1 Overview
    2. 7.6.2 Binder selection
  7. 7.7 Use of Fly Ash in Rigid and Composite Pavements
    1. 7.7.1 Overview
    2. 7.7.2 Advantages of using fly ash in concrete
    3. 7.7.3 Optimum mix design
  8. 7.8 Use of Fly Ash in Sub bases
  9. 7.9 Use of Fly ash in Concrete Bases
    1. 7.9.1 Cement and fly ash content
    2. 7.9.2 Compressive and flexural strength
  10. 7.10 References

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