Properties of Hot Mix Asphalt Containing Treated Recycled Concrete Aggregates Using SCB and ITS Tests

Recycling of Construction and Demolition Waste (CDW) with the purpose of re-using these in construction projects has substantial benefits for the environment and for conservation of natural aggregates resources. Recycled Concrete Aggregates (RCA) that are derived from buildings, concrete structures or distressed PCC pavements can be used in various applications. This paper reports results of the experimental study on the application of demolished concrete aggregates in preparing Hot Mix Asphalt (HMA). RCA materials were used both in their original form; and, treated before that these were added to HMA mix. Two treatment methods were applied to coarse RCA materials. Treatments were consisted of; one, a two-stage treatment of RCAs, using acid and a pozzolan material (calcium metasilicate, named Wollastonite); two, applying hydrated lime solution to RCAs. Physical and mechanical characteristics of the treated/untreated RCAs were determined. Various asphalt mixtures with different amounts of RCAs were prepared. Moisture susceptibility and fracture properties of mixes were determined, using Indirect Tensile and Semi-Circular Bending (SCB) testing methods. Results indicated that although treating RCAs might require more effort in production processing, significant benefits will result in reducing moisture susceptibility and increasing fracture resistance of HMA mixes containing treated RCA materials. It was also found that replacing natural aggregates with RCA, improved fracture properties of asphalt mixes appreciably.