A high wet-weather accident rate on highways is a general indication of the low skid-resistance of the pavement surface. The polishing of aggregates under the vehicle tires decreases the microtexture, which is an important component of the skid resistance of the pavement. The rate of polishing depends on the mineralogical characteristics and the texture of the aggregates. A detailed laboratory study was conducted on different aggregate sources in puerto rico and their polishing characteristics by means of a British polishing wheel. It was found that carbonate rocks polish more than gravels and noncarbonate rocks. In a follow-up study, field data were collected on accident rates, pavement surface friction, and macrotexture of in-service flexible pavements. Samples also were collected from selected pavements to determine polish resistance and carbonate content of the recovered aggregates. Statistical analyses indicated that the relationship between the wet/dry accident ratio and pavement surface friction was statistically significant. Carbonate content of the aggregate showed better correlation with pavement surface friction than polished stone values, although both had significant influence. On the basis of the results, recommendations were made with respect to specifications of aggregates to ensure adequate skid resistance.
Samenvatting