Utilisation of aggregate materials in road construction and bulk fill

In the UK, at present, the majority of aggregate materials, for all constru ction applications, are obtained from primary resources such as crushed roc k and sand and gravel. Material extraction results in many adverse environm ental impacts and utilisation consumes a finite natural resource. In the UK we also produce large quantities of waste and by-product materials, from i ndustrial and domestic activities, that require management or disposal. To maintain levels of development and construction but reduce the utilisation of primary aggregates, two principal options are available: optimise the us e of primary materials or utilise alternative materials. This paper summari ses ongoing research at the University of Nottingham, UK, which addresses b oth of these issues for aggregates used in road construction and bulk fill. Predictions of the in situ performance of alternative and conventional agg regate materials have been investigated as regards both mechanical and envi ronmental loading. Performance based mechanical specifications have been de veloped using a repeated load triaxial test and indirect tensile test for a ssessing untreated and treated materials. For the investigation of environm ental performance, a tank-leaching test and lysimeter trials have been util ised. In addition, the CoURAgE project (a European-wide research, collabora tion, centred at Nottingham) has investigated possibilities for optimising the use of aggregate materials in the unbound layers of roads. Aspects of t hat project cover the importance of good design and construction techniques and, thus, are also focused on minimising the required quantity of natural aggregate material. (C) 2001 Elsevier Science B.V. All rights reserved.