Macrotexture characterisation of laboratory-compacted hot-mix asphalt specimens using a new asphalt polishing machine

Highway agencies continuously strive to maintain adequate surface friction (or skid resistance) at the interface between vehicle tyres and pavement surfaces to enhance the available friction during all phases of a pavement life time. Conventionally this is attained by monitoring and ultimately overlaying the pavement surface deficiencies. However, this practice is an inactive approach in solving the problem. A more proactive approach would be to carry out the necessary hot-mix asphalt testing in a laboratory setting before construction or during its initial mix design stage. Towards this objective the polishing behaviour of laboratory-prepared specimens has been investigated in terms of friction and macrotexture values. The potential relationship between friction and texture measurements has also been considered. The new asphalt polisher showed a good degree of repeatability. The macrotexture was found to be a significant factor in controlling the frictional properties of asphalt surfaces which was shown by the relatively high correlation between the mean texture depth (MTD) and the British pendulum number (BPN) values. Good correlation was also found when correlating Delta BPN and Delta MTD for each job mix formula and each group based on their polishing susceptibility. Test results of this study that are based on bituminous surfaces made from aggregates produced in Ohio could enrich the Ohio Department of Transportation material specification database for future usage.