A Comparative Experimental Investigation on the Performances of Waste Plastic Modified Hot Mix Asphalt in Dry and Wet Processes

Abstract

Virgin bitumen as a binder is very costly and also needs an improvement in pavement performance due to an ever-growing traffic. Plastic-modified binder application for hot mix asphalt is the way to solve this problem by dry and wet modification processes. Here the main gap is comparative study and the application of an optimized modifier process. Therefore the objective of the current study was to establish a comparative experimental investigation on the performance of waste plastic-modified hot mix asphalt in dry and wet processes. Here, to compare the performances of dry and wet processes, material tests, Marshall properties, rut resistance and moisture sensitivity performance evaluation, multi-criteria decision analysis (technique for order of preference by similarity to ideal solution), and simple cost comparison are applied using optimum plastic contents for dry and wet as 14.3 % and 2%, respectively. Based on the above approaches the result of aggregate tests (specific gravity, water absorption, aggregate crushing value, flakiness index and soundness for fine and coarse aggregate) are 2.517, 1.58%, 13.3 %, 16.45 %, 3.04 % and 5.08 % respectively. The results of the bitumen test (specific gravity, ductility, penetration and softening point) are 1.024 g/cm??, 125 cm, 64.35 and 50.1oc. The stability, flow, bulk specific gravity, voids filled by mineral, voids filled by air, and voids filled by asphalt of the dry process are 21.26 KN, 2.35mm, 2.207 g/cm??, 16.69 %, 4.94 %, and 70.39 %, and the wet process is 16.42 KN, 2.47 mm, 2.199 g/cm??, 17.01 %, 4.85 %, and 71.53 %, respectively. For dry process, rutting depth and wheel tracking rate are 1.31 mm and 0.000065 mm/pass and for that of wet are 2.39 mm and 0.00012 mm/pass, respectively. Again, the closeness coefficient for dry is 0.97 and for wet is 0.487. The cost reduction found in the dry processes is 7.831 % and 1.05 % for that of wet from the conventional. Therefore dry process is attractive as well as selective for its performance and cost effectiveness.