Quantifying the effective mobilized RAP content during hot in-place recycling techniques

Abstract

The utilization of in-place recycling techniques is capable of consuming 100% reclaimed asphalt pavement (RAP). Hot in-place recycling (HIR) is one of the promising techniques to rehabilitate the pavements suffering from minor cracking issues through heat scarification, additive injecting, mechanical mixing, and compacting. However, the main concern of using 100% RAP in HIR remains as how much RAP can be activated and mobilized to coat the aggregates. In this study, a new approach named “ignition oven method”was developed to quantify the effective mobilized RAP content during HIR procedures by targeting directly into the ignition loss of the RAP binder. Various factors were considered including temperatures, heating methods, as well as the types and dosage of the additives. The commonly used Fourier transform infrared spectroscopy (FTIR) method was also adopted to validate the effective mobilized RAP content quantified by the ignition oven method. The results demonstrated that the ignition oven method is an effective tool for quantifying the effective mobilized RAP content, which is comparable to the FTIR methods. The temperatures and dosage of additives are critical in improving the mobilization of RAP and should be optimized to achieve a sustainable pavement.