Interface Bond Strength of Ultra-Thin Whitetopping (UTW) and Hot Mix Asphalt (HMA) Composites by Direct Shear

Whitetopping is a portland cement concrete (PCC) overlay that is constructed on the top of existing bituminous or hot mix asphalt (HMA) pavement. The design and construction of UTW over HMA enables the composite to act as a monolithic layer. This article presents the findings of a laboratory study performed on interface shear strengths of UTW and HMA composites by direct shear approach. The objectives of the study were to evaluate the main effects of (i) different interface treatments, (ii) variation in the design binder content of HMA, and (iii) temperature conditioning and moisture conditioning on the interface shear strength. Based on the results of interface shear strength tests, the range of bond strength of UTW-HMA was found to be 0.22-1.29 MPa. Other factors like age of UTW, temperature conditioning, and moisture conditioning also had significant effects on the interface shear strengths of UTW-HMA composites.