Evaluating the Performance of Half Warm Asphalt Mixtures Using Reclaimed Asphalt Pavement (RAP)

Abstract

This paper introduces a study of producing Half –Warm Asphalt Mixtures (HWAM) using Reclaimed Asphalt Pavement (RAP) and make a comparison of the performance of HWAM and hot mix asphalt (HMA) .The study aims to reduce the consumption of natural aggregate resources using the materials from the damaged pavement. In addition, it discusses the environmental/economic impact by minimizing the gasses emission and fuel consumption, as HWAM can be produced at low temperatures. Three types of mixes were prepared for this purpose. The first was the conventional Hot Mix Asphalt (HMA), named control mix which was prepared at 155oC and the second was the mix containing 70% RAP: 30% virgin aggregate and prepared at 155oC, named HMA-RAP. The third mix was HWAM which contained 70% RAP: 30% virgin aggregate and prepared at 90oC, named HWAM-RAP.HWAM was prepared using a binder modified with Ethoxylated Nonyl Phenol (NP9). The tried percentages of NP9 were 10, 15, 20, and 25% by weight of bitumen. Experimental tests were carried out to evaluate the engineering properties of mixes. All mixes were designed using the Marshall mix design method. Marshall stability and flow test, Indirect Tensile Strength (ITS) test, and Wheel Tracking test were conducted. The results showed that all mixtures achieved Marshall mix design limits. Producing HWAM-RAP increased Marshall stability, enhanced Marshall Quotient (MQ), and reduced the optimum asphalt content (OAC). A significant improvement was observed in ITS values for HMA-RAP and HWAM-RAP. The final rut depth decreased by producing HWAM-RAP compared to the conventional mix.