Specification of pulverised-fuel ash for use as general fill

The case for a new approach to the specification of pulverised-fuel ash (pfa - known as fly ash in many parts of the world) is made. The new approach is set within the context of the current Specification for Highway Works and associated Notes for Guidance (MCHW 1 and 2), such that it can be simply and rapidly incorporated into these documents. The new approach is thus proposed as changes to MCHW 1 and 2 to encourage the greater use of pulverised-fuel ash in general fill, whilst ensuring the continued construction of stable earthwork structures. Guidance on the use of pulverised-fuel ash in earthworks is also given. (A)