Size effects of rubblised PCC on HMA overlay performance

Abstract

The technique of placing hot-mix asphalt (HMA) overlay over a rubblised Portland cement concrete (PCC) pavement is a preferable way of rehabilitating severely deteriorated rigid pavements in south-west China. To investigate fragment size effects of the rubblised PCC on the performance of the HMA overlay, two full-scale experiments were carried out in a controllable environment. Strain development in the HMA was evaluated using data collected by strain sensors embedded at the overlay bottom. It was found that the performance of the overlay under repeated loadings was closely related to the fragment size distribution as well as the initial modulus of the rubblised PCC before the HMA was placed. For overlay paved over rubblised PCC with an insufficient amount of medium-sized fragments, tensile strains at the HMA overlay bottom increased with loading repetitions at a relatively high speed. However, if the fragments of rubblised PCC were graded relatively uniformly, particularly if the gradation matched the requirement for the crushed stone base of the flexible pavement, tensile strains at the HMA overlay bottom developed at a slower pace, indicating an improvement in the deterioration resistance of the overlay system to dynamic loads.