Thermal cracking potential in asphalt mixtures with high RAP contents

Abstract

Asphalt recycling is a key component of the sustainable practices in the pavement industry. Use of reclaimed asphalt pavement (RAP) minimizes the construction cost as well as consumption of natural resources. Adding RAP, though, is believed to make the asphalt mixtures prone to thermal cracking by increasing their stiffness. A semi-circular bend (SCB) test was conducted to evaluate the low temperature cracking potential of asphalt mixtures with RAP, whereas, a flow number test was conducted to provide some insight into the gained stiffness. Eight asphalt mixtures with a high amount (up to 50%) of RAP were designed using two material sources. Two additional softer binders were used to prepare testing samples in order to evaluate the effect of binder grade bumping. Flow number test data showed significant improvement in potential rutting resistance of asphalt mixtures when RAP was added. However, thermal cracking potential may increase when RAP is added to asphalt mixtures. This effect could be reduced when binder double-pumped grade is used. © RILEM 2012.