Using RAP Material in High Modulus Asphalt Mixture

With the purpose of improving the high temperature rutting resistance of recycling asphalt mixture, the design concept of high modulus asphalt mixture (HMAM) was adopted to design recycling asphalt mixture in this study. Control HMAM was designed to prepare recycling high modulus asphalt mixtures (RHMAMs) with different contents of reclaimed asphalt pavement (RAP). Performance tests including simple performance test (SPT) test, wheel tracking test, low-temperature bending beam test, immersion Marshall test, freeze-thaw splitting test, and bending beam fatigue test were conducted to evaluate the dynamic modulus, high temperature rutting resistance, low-temperature cracking resistance, moisture stability, and anti-fatigue performance of RHMAMs. This paper proves that the addition of RAP can improve the high temperature rutting resistance of HMAM while jeopardizing its low temperature cracking resistance, moisture stability, and anti-fatigue property. With RAP content increasing, the dynamic modulus and dynamic stability of RHMAMs increase while the failure strain, tensile strength ratio, and fatigue life of RHMAMs decrease. With 20 %-30 % of RAP, RHMAMs have similar performances to HMAM without RAP. With 40 %-50 % of RAP, while the dynamic stability and moisture stability of RHMAMs can meet the requirements by Chinese specification, the low-temperature failure strain of RHMAMs was already lower than the requirements by Chinese specification and the fatigue life of RHMAMs degraded obviously compared to that of the HMAM. It is indicated that RHMAMs can provide satisfied high temperature rutting resistance and moisture stability while its low-temperature cracking resistance and anti-fatigue property needs to be paid attention to.