Feasibility of Using Unprocessed Reclaimed Asphalt Pavement Aggregates in Concrete Paving Applications

Over 40% of US roads are in either poor or mediocre condition. Rehabilitation of these roads will add to the influx of Reclaimed Asphalt Pavement (RAP), particularly in urban areas. Like the City of San Antonio, many urban transportation authorities end up selling these RAP generated from road milling at a very cheap rate to third-party contractors, who use these with virgin materials to produce Hot Mix Asphalt (HMA). This study aims to investigate the feasibility of using RAP as a fine aggregate replacement for Class-A(3,000psi) cement concrete, which the transportation authorities may potentially gain substantial monetary savings. For the study, RAP was collected from a road milling site and the city stockpile, then separated using sieve #8 to Fine RAP (FRAP) to cast concrete, replacing 25%, 50%, 75%, and 100% of the virgin fine aggregate. The Class-A concrete mix design currently used for the San Antonio sidewalks was used to compare with FRAP concrete. The present laboratory investigation found that partial replacement of virgin fine aggregate with FRAP (25%, 50%, and 75%) increases the compressive strength of concrete. Washing of FRAP was found not to alter concrete compressive strength significantly. Splitting tensile strength was found to be 8-10%, and flexural strength was 16.65% of the corresponding compressive strength. The study concludes that up to 75% FRAP concrete can be used for Class-A concrete applications for the City of San Antonio, which can result in an estimated saving of 9.56% of the total concrete cost.