Laboratory prediction of early life asphalt surfacing properties

This paper summarises the findings of a laboratory investigation to assess whether it is possible to rank the relative performance of 10 different asphalt surfacing materials made with the same aggregate. The Road Test Machine was used to simulate controlled trafficking conditions. The change in wet skid resistance and texture depth was determined at regular intervals during testing. It was found that wet skid resistance increases as nominal stone size decreases for the AC and SMA mixes and decreases with increasing application of 20mm chippings for the HRA. Texture depth increases as the nominal stone size increased. The AC mixes were least durable and suffered most from surface ravelling in the later stages of testing. The SMA mixes were more durable with the HRA having the best durability. The resulting data suggests that it is possible to improve understanding of the complex inter- relationships between asphalt mix properties such as asphalt type, nominal aggregate size, skid resistance and texture depth and how they develop with time. The testing protocols offer a means of optimising the sustainable development of asphalt surfacing materials