Effect of Recycled Aggregates and Polymer Modified Bitumen on the Marshall Properties of Hot Mix Asphalt- A Case Study

Abstract

The engineering infrastructures after serving their purpose are usually demolished and dumped in the surroundings as per existing local guidelines particularly due to a lack of disposal strategies. In addition to wasting engineering resources, this practice pollutes the environment. Therefore, the current study looked at the usage of demolished engineering wastes for useful engineering purposes in order to minimize paving expenses as well as environmental pollution. The prime objective of this study is to evaluate the conventional asphalt mixture in terms of Marshall mix design, and consensus properties, and compare results with those obtained for asphalt mixture containing recycled aggregates from demolished wastes. The conventional asphalt mixtures were prepared with conventional materials, and the modified asphalt mixtures were prepared with varying proportions of recycled coarse aggregates, ranging from 0% to 75%, and tested as per the procedure outlined in ASTM D1559. The findings revealed that the stability of the mixes showed a decreasing trend with the increase in the proportion of recycled aggregates. This decline in stability is attributed to the debility in interlocking properties in asphalt mixture particularly due to poor surface friction, texture, and surface free energy of the recycled aggregate. Additionally, the percentage of air voids and voids filled with mineral aggregates increased. However, the laboratory findings indicated that the modified mixes at 25% recycled aggregate content exhibited comparable performance to conventional asphalt mixes, providing improved environmental advantages through the recovery and reuse of waste concrete aggregates. These findings highlight the potential of utilizing recycled aggregates in hot mix asphalt as a sustainable approach in asphalt pavement construction.