Predicting the potential of local aggregate in surfacing mixes without the risk of road trials

The selection of aggregate used in surfacing mixtures is typically based on PSV. Many years of product development and road testing has identified those aggregates that are considered safe and those that are not so good. The implementation of the Construction Products Regulation (CPR) in 1st July 2013 has resulted in standard and specification revisions to make them CPR compliant. Road trials are typically used in the later stages of BBA HAPAS or TS2010 product accreditation to prove performance of the system. This paper considers how the potential performance and durability of surfacing systems can be assessed without the risk of something going wrong in full-scale trials. The investigations are based on test slabs subjected to accelerated simulated trafficking. The development of properties such as skid resistance and texture depth are determined through the early, equilibrium and later stages of life. This allows combinations of good and what may be traditionally regarded as unlikely local aggregates and mix types to be quickly assessed under the same conditions. Examples of local aggregate use that would typically not be considered suitable as a surfacing are given in this paper.