Simple Laboratory Method for Measuring Pavement Macrotexture

Pavement surface friction influences traffic accident rates, especially during wet weather, and is affected by pavement surface texture as characterized by microtexture and macrotexture. This study investigated the utility of measuring pavement surface macrotexture in the laboratory by using the aggregate image measurement system (AIMS) on cores extracted from pavement sections. Texture measurements made in the laboratory with AIMS were compared with texture measurements made on the pavement with the circular track meter (CTMeter). Previous research established a strong correlation between the mean profile depth (MPD) from the CTMeter, which considered averages of maximum heights, and the mean texture depth from the sand patch test, a volumetric method that was the accepted standard for macrotexture measurement. Similarly, in this study, statistical analysis showed a good correlation between the MPD values from AIMS measurements on pavement cores, based on analysis with 50-mm (2-in.) scan line segment lengths, and the MPD measured on the pavement in the field with the CTMeter. Further analysis using root-mean-square (RMS) values that considered all height measurements showed that the proposed procedure with AIMS was sensitive to the direction of the texture measurement scans and could therefore distinguish traffic direction across the core. The mean RMS values from AIMS also had a fairly strong relationship with the MPD values measured on the pavement by the CTMeter. Finally, the results indicated that a set of three directional scan lines could be used on the cores instead of four directional scan lines and the conclusions were still valid.