Laboratory Performance of Stabilized Base with 100% Reclaimed Asphalt Pavement (RAP) Using Portland Cement, Bitumen Emulsion and Foamed-Bitumen

Abstract

While substantial research has focused on incorporation of Reclaimed Asphalt Pavement (RAP) in hot-mixed asphalt mixtures, there is a knowledge gap related to performance of stabilized base courses. This study evaluated the laboratory performance of stabilized base courses with 100% RAP and total stabilizing agent amount of 3% (by weight of RAP). Three stabilizing agents (Portland cement, foamed bitumen, and bitumen emulsion) are evaluated individually and in combination (1.5% Portland cement with 1.5% foamed bitumen, and 1.5% Portland cement with 1.5% bitumen emulsion) to determine the optimal stabilization method using laboratory performance tests and pavement design analysis. Performance evaluation was conducted using the resilient modulus (M_r) test to determine the structural contribution and semi-circular bend (SCB) test for cracking resistance. Pavement designs were done using measured M_r values to compare pavement structures with equivalent structural capacity. Semi-circular bend (SCB) test indicates intermediate temperature cracking resistance of materials using various performance indices (fracture energy, fracture strength, flexibility index and rate-dependent cracking index). The use of Portland cement results in considerably higher stiffness and consequently a thinner pavement structure, but with a significant increase in cracking susceptibility. Mixtures stabilized with foamed bitumen tend to be stiffer than those stabilized with bitumen emulsion but have comparable cracking properties.