Pavement Surface Macrotexture Measurement and Applications

Different techniques for measuring pavement surface macrotexture and their application in pavement management are discussed. The main applications of surface macrotexture are to measure the frictional properties of the pavement surface and to detect hot-mix asphalt (HMA) construction segregation or nonuniformity. Since surface macro-texture can be measured quite efficiently using noncontact technologies and provides important information regarding pavement safety and HMA construction quality, this parameter may be included in the quality assurance or control procedures. Correlations between different measuring devices were investigated utilizing different HMA wearing surfaces. Excellent correlation was found between the circular track meter and sand patch measurements. In addition, the macrotexture determined using a laser profiler correlates well with that determined with sand patch measurements. Consistent with previous studies, it was found that the skid number gradient with speed is inversely proportional to the pavement macrotexture. However, there was a noticeable difference in speed dependency when smooth and ribbed tires were used. Oscillations in the percent normalized gradient with time due to seasonal variations were also observed. Macrotexture measurements hold great promise as tools to detect and quantify segregation for quality assurance purposes. A standard construction specification was proposed in a recent NCHRP study. However, the equation proposed for computing the nonsegregated estimated (mean) texture depth could not be applied to the mixes studied. An alternative equation has been proposed, which estimates the surface macrotexture using the mix nominal maximum size and voids in the mineral aggregate. The study was based on the mixes used at the Virginia Smart Road. Further investigation using other mixes is recommended.