Most of road networks are constructed using hot mix asphalt (HMA). HMA is used for roads construction and maintenance at high temperature (150-170˚C) requiring high fuel consumption. In addition, gases emissions generated from HMA are issues of concern among the pavement researchers. Therefore, reducing gases emission and mixing temperature is an objective toward sustainable asphalt pavement industry. Thus, using warm or half-warm asphalt mixes as a modern technique are considered suitable alternatives to HMA. This study aims to reduce gasses emissions and manufacturing cost of HMA using half-warm mixes asphalt (HWMA). Chemical additives are used in order to produce HWMA at low temperature. In this study, Ethoxylated Nonyl Phenol (NP9) was used to enhance the performance of asphalt mixes at low temperature. The tried percentages of NP9 were 10, 15, 20, and 25% (by weight of bitumen). The tested mixes include control mix (mixed at 155°C) and modified mixes (mixed at 90°C, HWMA modified by NP9). Rolling thin film oven (RTFO), Marshall, moisture susceptibility, indirect tensile strength (ITS), wheel tracking, scanning electron microscopic (SEM) and gases measurements tests were carried out for control and modified mixes. The results indicated that, significant changes were occurred in modified mixes compared to the control mixes. Bitumen viscosity decreased by the increase of NP9 percentages. The optimum percentage of NP9 was 10% by weight of bitumen.The retained penetration of modified specimens by 10% NP9 was higher than conventional specimens by 40.26%. Also, the results showed that Marshall stability and Marshall Quotient (MQ) of HWMA enhanced by 15.22% and 11.58% respectively. Producing HWMA reduced the loss of stability by 18.10% and changed tensile strength ratio from 91% to 96% by an enhancement of 5.50% compared to the conventional mixes. In addition, the resistance of HWMA specimen against rutting was higher than or as same as the value of control specimen during the test period. From SEM test results, a significant change was observed for all tested specimens , the structure of control specimen under SEM was differ than the shape of modified specimens. Finally, the chemical analysis showed that the gases emissions reduced by manufacturing HWMA at 90C.

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.