Comparison of RCA and CDW Wastes as Substitutes for Coarse Aggregates in a Hot Mix Asphalt

Abstract

Several research efforts have been carried out throughout the world with the purpose of evaluating if recycled concrete aggregates (RCA) can be useful as substitutes for natural aggregates (NA) in hot mix asphalts (HMA). Contrary to this, little research efforts have been carried out in order to evaluate the possible use in HMAs of construction and demolition wastes (CDW), which are where RCAs are derived from. The objective of this research was to compare mechanical resistance under monotonic load (Marshall and Indirect Tensile Tests) and moisture damage undergo by a HMA when the coarse fraction of NA is partially substituted by a CDW and an RCA. A secondary objective was to avoid increasing the cost of HMA by using the same optimal asphalt content in the control mix when substitutions were carried out. With the purpose of knowing if changes in measured properties were statistically significant, an ANOVA variance analysis test was carried out. A general conclusion obtained in this research was that by substituting NA with RCA and CDW in 20% by mass, HMA mixes reduce their resistance under monotonic load as well as their moisture damage resistance. Said reduction was more significant in mixtures that used CDW as a product of the shapes of its particles and the presence of materials that reduce adherence with asphalt, such as ceramic, glass, and wood, among others. Despite this, the mixture that used RCA complied with quality requirements demanded for use in roadways with low and medium traffic volumes.