Laboratory investigations on the utilization of RCA in asphalt mixtures

Considerable usage of natural aggregates for road construction, and at the same time, the increasing amount of solid wastes, have attracted the attention of many researchers in the pavement industry to investigate the feasibility of the application of some of the waste materials in pavement construction. Construction and demolition wastes, including Recycled Construction Aggregate (RCA) constitute a major part of the municipal solid wastes. Using RCA in asphalt mixtures generally results in significant economic and environmental benefits. However, in spite of such promising potentials, insufficient and inconclusive data and information on the engineering properties of RCA had limited the reliability and design specifications of RCA to date. In light of this, this paper aims to investigate the feasibility of the application of RCA in asphalt mixtures. As the suitability of aggregates for using in asphalt mixtures is determined based on the aggregate characteristics, an experimental program is set up to evaluate the physical and mechanical properties of RCA. This laboratory investigation included the measurement of RCA compressive strength, particle shape, water absorption, flakiness index, crushing value, weak particles, wet/dry strength variation, and particle density. Based on this research, it was observed that RCA has a lower value of flaky and misshapen particles in comparison with basalt, implying that asphalt mixtures containing the certain amount of RCA can have better workability, deformation resistance and compaction. However, the test results show higher water absorption and wet/dry strength variation for RCA compared to natural materials, emphasizing on the necessity of an appropriate mix design. © 2018 Chinese Society of Pavement Engineering