The possibility of reusing recycled aggregates in the production of hot mix asphalt

Abstract

The use of aggregates resulting from destroying concrete as a substitute for natural aggregates in the production of hot mix asphalt for roads with high traffic loads reduces natural consumption and the amount of scattered waste. The study was conducted by designing the hot mix asphalt using the Marshall method with different proportions of recycled aggregate. The results showed an improvement in the stability, flow and indirect tensile tests of the aggregate compared to the conventional mixture. An increase in the recycle aggregate leads to an increase in the proportion of air voids, but it also leads to a decrease in the proportion of voids in the aggregate and asphalt-filled voids. The optimum bitumen content increases with the amount of recycled concrete. Recycled aggregate can be used as a substitute for natural aggregate in hot mix asphalt design successfully. The study found that increasing the percentage of recycled concrete (RCA) in hot bituminous mixtures led to an increase in air voids (VA) and a decrease in voids in mineral aggregates (VMA) and voids filled with asphalt (VFA). However, these percentages decreased with the increase in RCA due to the behavior of the recycled aggregates under load. The optimum bitumen content (OBC) also increased with the increase in RCA. The asphalt mixture's resistance to tensile stress increased with the increase in RCA up to 50% and at 25˚C and RCA 40˚C by up to 8%. The process of using recycled aggregates as an alternative to natural aggregates in hot bituminous mixtures is applicable up to a certain percentage.