Low-grade quarry products, reclaimed aggregates and inert wastes — Their use in unbound mixtures for road pavements

Abstract The UK Specification for Highway Works appears to encourage the use of low-grade quarry products and a range of reclaimed aggregates and inert wastes in earthworks. However, in practice, materials used in earthworks are judged against requirements designed to assess the compactibility of soils. Compliance with “compactibility” criteria rather than “fit for purpose” criteria can lead to the use of higher quality aggregates than is strictly necessary. For many years U.K. clients have had supplies of good quality granular subbase material available at low cost. The use of such aggregates in non-structural fill layers presents few risks, but diverts the aggregate from more appropriate end uses, such as asphalts. Proponents of the greater use of wastes and reclaimed aggregates face the same dilemma. The development of European (CEN) Standards may influence the situation. These Standards are designed to ensure that barriers to trade are removed for “products placed on the market”. The new Standards aim to be “blind” to the source of the material and to reflect the wide range of national practices across Europe. The CEN work may give a status to a number of tests that are more appropriate to the control of unbound mixtures than those currently used in the U.K.