Recycled Concrete Aggregates (RCA)-based asphalt mixtures: A performance-related evaluation with sustainability-criteria verification

Abstract

This investigation aims to explore the feasibility of using Recycled Concrete Aggregate (RCA) as a partial replacement for Natural Aggregates (NAs) in the production of Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA). As WMA technology, Iterlow T (a chemical additive) was selected. For both types of asphalt mixtures, the RCA dosages of 0, 15, 30 and 45% by weight of coarse aggregates were considered. Notably, four different RCA sources were assessed, and the alkali-silica reaction and attached mortar quantity were analyzed for each one. In order to examine the effect of the coarse RCA on the performance-related properties of the asphalt mixtures, a test protocol was conducted. This protocol comprised four tests, i.e., stiffness modulus, moisture susceptibility, rutting resistance, and fatigue life. Additionality, a sustainability-criteria verification was performed employing the Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) methodologies. Respectively, the LCA and LCCA estimate each alternative's environmental impacts and production costs. Consequently, the main finding obtained were: (i) as the coarse RCA content increases, asphalt mixtures exhibit a reduction in their mechanical performance; (ii) the performance-related properties of the HMAs and WMAs with a 15% RCA dosage are acceptable, but more elevated amounts generate highly noticeable deterioration; and (iii) 15% of coarse RCA minimizes the environmental burdens and maximizes the cost-effectiveness of the asphalt mixtures fabrication. Thus, the main contribution to the literature that achieves this research is to perform a comprehensive multi-criteria examination on the potential of the RCA as a recycled material to minimize the depletion of non-renewable resources.