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

Abstract

This paper introduces a study of producing Half -Warm Mix Asphalt (HWMA) using Reclaimed Asphalt Pavement (RAP) and make a comparison of the performance of HWMA and hot mix asphalt (HMA) with and without RAP .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 gas emissions and fuel consumption, as HWMA 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 155 o C and the second was the mix containing 70% RAP: 30% virgin aggregate and prepared at 155 o C, named HMA-RAP. The third mix was HWMA which contained 70% RAP: 30% virgin aggregate and prepared at 90 o C, named HWMA-RAP. HWMA 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 HWMA-RAP increased Marshall stability, enhanced Marshall Quotient (MQ), and slightly changed the optimum asphalt content (OAC). A significant improvement was observed in ITS values for HMA-RAP and HWMA-RAP. The final rut depth of HWMA-RAP mixtures was almost as same as these values of the traditional mixtures. Finally , it can be concluded that HWMA-RAP performed as same as /better than the conventional mix.