Rutting Susceptibility and Moisture Damage of Hot Mix Asphalt Containing Recycled Asphalt Pavement

Abstract

Recycled Asphalt Pavement (RAP) use in pavement has increased a lot from the last two decades. RAP usage has now become common practice in many countries. Highway agencies around the world are endeavoring to use larger quantities of reclaimed asphalt pavement (RAP) in order to meet not only economical and environmental friendly but also to preserve natural resource and similar or even better performing hot mix asphalt (HMA) mixtures. Comprehensive road networks are a basis for economic development of any country. Overtime damages like rutting, moisture damage and cracking renders the pavement unusable. The use of reclaimed asphalt pavement (RAP) serves a distinct part in achieving the national goal of prosperity. This research work presents an experimental study to evaluate the effect of different percentages of RAP on the volumetric properties of asphalt mixtures. Mix design of one aggregate source and a RAP source using ½-in nominal maximum aggregate size was prepared. RAP material gradation was found and blended in the virgin aggregate gradation to get approximately our desired gradation with in specified limits of NHA. The mix designs included a control mix with 0% RAP and six samples of HMAs with 10%, 20%, 30%, 45%, 60% and 100% RAP to get an optimal percentage on which performance testing to be done after finding out the volumetric, stability and flow of RAP containing mixtures. NHA class-B wearing course gradation, ARL penetration grade of 60-70, aggregate source of Margalla and RAP from Islamabad Lahore Motorway (M-2) were used in this study.This research-study undertakes the rutting susceptibility and moisture damage in RAP incorporated hot mix asphalt (HMA) using Hamburg Wheel-tracking Device. Rutting resistance of Rap containing mixture is increased up to 24.7% for 20% RAP as compared to the controlled mixtures. Moisture damage results at 50°C temperature of water showed 20.7% increased resistance for 20% RAP containing mixture. This research showed that all tested HMAs with RAP performed better than the mixtures prepared with virgin aggregate. Cost comparison of control mix and Rap containing mixture was done on major asphalt production cost categories that how much their impact is on overall cost of any project. Comparison shows that RAP containing mixture can save the cost up-to 13.50%.