Pervious Concrete: Improving Design for Optimal Balance between Strength, Permeability and Sustainability

This study aims to optimize the design of pervious concrete by investigating the effects of aggregate shapes and different fine aggregate percentages on the properties of pervious concrete. Pervious concrete offers numerous sustainable environmental benefits mostly including reduction of storm water runoff, recharging of groundwater, skid resistance enhancement of pavement surface and traffic noise reduction. The main objective of this study was to achieve an optimum balance between two critical parameters (compressive strength and porosity) by analyzing various angularity numbers, flakiness and elongation indices and percentages of fine aggregate. Compressive strength test revealed that 8% fine aggregate pervious concrete samples performed optimally providing a balanced combination of strength and permeability. The results further revealed that lower fine aggregate content showed excellent porosity but significantly lower strength whereas higher fine aggregate content showed increased compressive strength but reduced permeability. Further analysis of aggregate types revealed that normal coarse aggregates (angularity number 6.9) provided a favourable balance between compressive strength and permeability. The results further showed that high angularity coarse aggregates resulted in improved strength but with slightly reduced porosity while as rounded aggregates provided better porosity but reduced strength due to their smoother surfaces and reduced interparticle bonding. Flaky aggregates negatively affected both strength and porosity due to weaker particle bonding and poor mutual bonding. Therefore, the best performing mix was identified as the mix with 8% fine aggregate content and normal coarse aggregate (angularity number 6.9) providing a favourable balance between compressive strength for structural applications and porosity for water infiltration with compressive strength of 27.5 MPa and permeability of 1.11 mm/s after 28 days of curing.