Evaluating the Use of Recycled Concrete Aggregate in Pervious Concrete Pavement

Pervious concrete with minimal fine aggregate and a high void content is a green alternative to conventional pavements. Pervious concrete allows water to infiltrate through the pavement and thereby reduces the requirement for storm water management systems. Virgin aggregate sources within Canada are limited, and other sources need to be evaluated for use. Recycled concrete aggregate (RCA) is obtained from decommissioned curbs and gutters, sidewalks, and parking lots. Using RCA in new concrete offers several environmental advantages: reducing dumping at landfill sites, reducing gravel mining, and reducing hauling of virgin aggregate and therefore reducing emissions. The purpose of a research study was to incorporate RCA into pervious concrete to create a very sustainable concrete product for paving. The research methodology involved substituting the coarse aggregate in the pervious concrete with 15%, 30%, 50%, and 100% RCA. Cylinders were cast in the laboratory for each percentage of RCA and a control mix containing only virgin aggregate. Fresh concrete tests were done, and the cylinders were tested for compressive strength, permeability, and void content. Testing showed that pervious concrete containing 15% RCA had strength, permeability, and void content that were very similar to those of the control mix. Samples that contained 30% RCA or greater had a significant loss in strength and increase in permeability and void content. Based on the specific mix design and RCA quality used in this research, the recommendation is that the optimum percentage of RCA in pervious concrete be 15% direct replacement of virgin coarse aggregate.