Performance of pervious concrete incorporating sawdust and coal waste for runoff water purification and pavement applications

Abstract The increasing frequency of urban flooding and water pollution necessitates the development of sustainable drainage materials with dual functional properties. Pervious concrete is a multifunctional paving material that addresses urban water management by allowing surface water to infiltrate through its interconnected voids. While its application has expanded due to its environmental benefits, its capacity for runoff water purification remains underexplored. This study examines the integration of sawdust and coal powder—two low-cost, biodegradable waste materials—into pervious concrete mixtures to enhance their pollutant filtration efficiency without significantly compromising structural integrity. A comprehensive experimental program was conducted using different aggregate sizes (12 mm and 25 mm, as well as blended combinations of these sizes) in both control and modified mixes containing sawdust and coal additives. The mechanical performance (compressive, tensile, and flexural strength), physical properties (density, porosity, void ratio), and environmental functionality (permeability, infiltration rate, turbidity reduction, sulfate and acid resistance, and clogging potential) were evaluated. Results demonstrate that while the addition of sawdust and coal leads to a moderate reduction in mechanical strength (10–25%), it significantly improves turbidity reduction (up to 65%) and chemical resistance. Mixtures with smaller aggregate sizes exhibited higher pollutant removal efficiency due to increased filtration pathways and additive interaction. The study presents an eco-functional pervious concrete system demonstrating balanced mechanical and hydraulic performance, with potential application in low-traffic pavements, green infrastructure, and stormwater treatment zones.