STUDY OF HOT MIX ASPHALT CONTAINING RECYCLED CONCRETE AGGREGATES THAT WERE MECHANICALLY TREATED WITH A LOS ANGELES MACHINE

Great quantities of recycled concrete aggregates (RCA) are produced as waste throughout the world. The foregoing study evaluated within a laboratory, the possible use of RCA when it is incorporated as a substitute for the coarse aggregate in a HMA19 Hot Mix Asphalt. The main problem in the use of RCA in HMA is its high absorption originated by the mortar that coats the particles. This generates an increase of optimum asphalt content within the mix and increases production and construction costs. In addition, said adhered mortar is fragile and brittle. In order to solve such problem, mechanical treatments were carried out on the RCA aggregate's surface by using 50, 100 and 200 revolutions in the Los Angeles machine. Marshall, Indirect Tensile Strength - ITS (under dry and wet conditions), moistures damage resistance (Tensile Strength Ratio – TSR) and Cantabro tests were carried out on HMA mixtures using RCA (with and without the mechanical treatment). An (ANOVA) variance analysis was carried out in order to verify if the results obtained are statistically significant. A general conclusion reports that the superficial treatment of the RCA aggregate in the Los Angeles machine contributes to the increase of resistance under monotonic load, reduces the volume of air within the mix, increases ITS under moisture conditions as well as TSR, which provides better cohesion, adherence and moisture damage resistance. This especially happens when subjecting RCA to 100 and 200 revolutions in the mechanical treatment. However, when using RCA, there is an increase in Cantabro abrasion with regards to the control mix. However, said increase is not statistically significant and mechanical treatment helps to improve response within the test.