The use of reclaimed asphalt pavement (RAP) aggregates in concrete

Abstract

The paper presents a laboratory study on the properties of ordinary Portland cement (OPC) concrete made with reclaimed asphalt pavement (RAP) to substitute natural aggregate. RAP aggregates were incorporated in concrete on the basis of maximum packing of the particles to provide a mixture with minium voids and thus optimum performance. Concretes were made with various combinations of natural and reclaimed aggregates. The resultant mixtures were: o a) control mixture using natural sand and natural gravel. b) mixture containing reclaimed coarse aggregate and reclaimed fine aggregate. c) mixture containing reclaimed coarse aggregate and natural sand. d) mixture containing reclaimed coarse aggregate and natural sand where 30% of the ordinary Portland cement was substituted with fly ash (FA). The weight composition and water/binder ratio was the same for all the mixtures. The results of the study show that RAP aggregates reduce the compressive and tensile strength of concrete and that the reduction is proportional to the percentage of RAP used. Fine and coarse RAP cause more reduction than coarse RAP and sand. Of the mixtures containing RAP, the use of coarse RAP aggregate with OPC or OPC+FA did not affect the engineering properties of concrete, however, the performance properties were much improved with the use of fly ash as indicated by the measurements of porosity and permeability. The RAP concrete mixtures exhibited enhanced ductility and high strain capacity when compared to the control concrete mixture. These improved properties can be useful for the use of RAP aggregate concrete in the construction of road bases and sub-bases. The material is also potentially of use for all non-structural purposes.