Combine Effects of Natural and Recycled Concrete Aggregate on Behavior of Asphalt Mix

Abstract

Recycled concrete aggregate (RCA) has gained consideration as one of promising reusable materials in asphaltic pavement. The RCA is a result of the demolition of reinforced concrete blocks, removing the steel reinforcements and breaking them into smaller sizes. RCA can be considered as a low-cost solution to crushing natural raw materials, concrete aggregate makes projects sustainable, it has smaller carbon footprint, reduces the of natural aggregate depletion, takes less energy than mining new. The use of natural aggregates from quarry crushers is increasing significantly with the continuous and increasing development in the construction of infrastructure. Therefore, it is necessary to invent the products of building rubble and recycling their waste because of economic, environmental, and continuity. In this study, the possibility of using RCA from building demolition waste in asphaltic mix, in combination with natural aggregate is explored. RCA was considered as 0%, 25%, 50%, and 60% of the weight of dry aggregates. Two grade of asphalt were used in this study namely, viscosity grade-30 (VG 30) and a polymer modified asphalt binder (PMB-40). The RCA was used as coarse and fine fractions and the filler was used as hydrated lime. The behaviour of asphalt mix composed of different combinations of RCA and natural aggregates were determined using volumetric, indirect tensile strength, moisture damage and the rutting properties. The results showed an increase in optimum bitumen content in the design mixtures with an increase in the percentage of RCA. In addition, mix prepared with polymer modified bitumen and combinations of RCA-NA indicates improvement in indirect tensile strength, moisture damage resistance and rutting resistance properties as compared to RCA mix prepared with virgin asphalt binders. Inclusion of hydrated lime as filler enhanced the resistance to moisture damage properties of the RCA mix, irrespective of the asphalt binders. Overall study concluded that optimum percentage of RCA can be considered up to 50% for better performance of asphalt mix.