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 (Mr) test to determine the structural contribution and semi-circular bend (SCB) test for cracking resistance. Pavement designs were done using measured Mr 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.