Assessing Shear and Compressive Strength of Reclaimed Asphalt Concrete

The prime objectives for this study are evaluating the performance of recycled asphalt concrete, investigating the effect of recycling agent type and amount on mixture performance, and studying the effect of inclusion of more reclaimed materials content into recycled mixtures. For this purpose, reclaimed materials milled from field, filler, virgin asphalt cement, and four types of recycling agents (used oil, oil + crumb rubber, soft grade asphalt cement, and asphalt cement + sulfur powder), have been implemented and were used to prepare recycled mixtures with nominal maximum size of 12.5 mm. The recycling agent that showed the best mixture performance was used to prepare recycled mixtures with different reclaimed materials contents. Mixtures were subjected to Double Punch shear, Compressive Strength, and index of retained strength Test. It was found that using soft grade asphalt cement as a recycling agent revealed better performance than other types of recycling agents. For recycled mixtures with mixing ratio of (50/50) virgin/reclaimed materials, the optimum recycling agent contents were (0.56%, 1%, 1.3%, and 1.5%) by weight of mixture for (used oil, oil + crumb rubber, soft grade asphalt cement, and asphalt cement + Sulfur) recycling agent respectively. Recycled Mixtures with reclaimed materials content, up to 70 %, and soft asphalt recycling agent, showed good performance. The percentages of variation for mixtures properties compared to mixtures with 50 % reclaimed materials were +3.6 %, +4.8 % for double punch shear, and compressive strength respectively, and the reduction in mixtures properties as compared to virgin mixture was in acceptable extent.