Correlating Aggregate Polish Susceptibility to Limestone Concentration Using X-Ray Diffraction

To minimize the occurrence of friction loss through polishing, pavements must be constructed from polish-resistant aggregates. Research has shown that limestone aggregates with high concentrations of carbonates are highly susceptible to polishing. Identifying polish-susceptible aggregates in the laboratory before they are placed on the road surface can help reduce accidents and save lives. Seven aggregate sources from nine field sites throughout Utah were identified by the locked-wheel skid trailer (LWST) to have low friction surfaces. A correlation between carbonate content, determined using X-ray diffraction (XRD), and accelerated polish testing was developed. Additionally, a correlation between field testing and laboratory testing was developed between the results of XRD and LWST testing. The correlations were characterized by high coefficients of determination, indicating that carbonate content is highly correlated to both polish susceptibility and field friction values. These correlations can be used to help reduce risk to the traveling public and predict pavement friction values before placing new asphalt.