DURABILITY AND PERFORMANCE CHARACTERISTICS OF DBM WITH WARM MIX ADDITIVES

Abstract

Environmental awareness which is rising due to increasing global warming, which in turn putting pressure to each and every country to restrict their carbon emission had led to the development of warm mix asphalt (WMA). Warm Mix Asphalt (WMA) is a new technique of production of asphalt mixtures, which comes into existence after the Kyoto protocol in early 1990's. Generally Warm mix Asphalt produces mixtures at 200 to 30°C lesser temperature than Hot Mix Asphalt (HMA) by reducing the viscosity of binders mainly by foaming and chemical technique. Now a day's various WMA technique has been developed by researchers such as Aspha-min, Evotherm, Sasobit, WMA-foam, Rediset etc. The reduction in mixing and Compaction temperature of the mix results in the saving of energy which in turn result in lower cost of the project, lesser emission of gases leads to better site conditions for the workers, and it also increases the working season in extreme weather conditions. The results of the strength, durability and performance characteristics of the Warm Mix Asphalt comes satisfactory as compared to Hot Mix Asphalt (HMA) and sometimes it gives even better results. The main advantage of using WMA is to reduce the mixing and Compaction temperature, which results in saving of energy with similar or better strength, durability and performance characteristics as HMA. The present study is focused on the laboratory performance of the Dense Bituminous mixture grade using three types of virgin bitumen binders i.e. VG- 30 (unmodified), PMB-40 and CRMB-60 (modified) binders with three types of Warm mix additives namely Sasobit, Rediset and Evotherm in optimum doses. Density and Compaction Temerature curve has been drawn for each type of Warm Dense Bituminous Mixes and it is found that PMB-40 binder gives the highest Density with respect to other two binders. Although the addition of the Evotherm in the virgin curve gives the maximum Density as compared with other additives and this trend is followed in all the virgin bitumen binders. Indirect Tensile Strength Test (ITS) gives better results for modified PMB-40 bitumen and Tensile Strength Ratio (TSR) test gives higher value with Sasobit as an additive.