Mix design for pervious concrete based on the optimization of cement paste and granular skeleton to balance mechanical strength and permeability

Abstract

• Mix design method for pervious concrete based on the optimization of cement paste and granular skeleton. • Validation using different w/b ratios, target porosities, and fine aggregate contents. • Measured air voids content for the designed mixtures met the corresponding target porosity, indicating the viability of the proposed method. • Designed mixtures achieved a compressive strength range of 11.9 to 28.3 MPa, tensile strength ≥2 MPa, and permeability coefficient ≥1 mm/s, meeting field application requirements for pedestrian and vehicle traffic. • Balanced mechanical strength, permeability, and resistance to degradation achieved especially in mixtures with 15% target porosity, w/b ratio 0.35, and 10% fine aggregate. The major concern for a broad field application of pervious is achieving mechanical performance and pore system efficiency to guarantee proper water infiltration. The inversely proportional relationship between mechanical strength and hydraulic conductivity demands mix-proportioning methods that equilibrate both requirements. This paper aims to fill this gap by proposing an easy-handling and flexible mix design method to optimize cement paste and granular skeleton composition to balance the mechanical strength and permeability of pervious concrete mixtures. The design concept was validated through an experimental program consisting of physical, mechanical, and hydraulic tests performed in designed pervious concrete mixtures considering three w/b ratios (0.30, 0.35, and 0.40), three target porosities (15%, 17.5%, and 20%), and three fine aggregate contents (0%, 10%, and 20%). Promising results were obtained in mixtures with 15% and 17.5% target porosity. The fine aggregate content influenced the permeability coefficient of the tested pervious concrete mixtures favorably. The fine aggregate content also influenced the compressive strength, especially in mixtures with 10% sand, which balanced the tested mechanical and hydraulic properties. The w/b ratio of 0.35 also resulted in pervious concrete mixtures with adequate functionality and balanced mechanical and permeability properties. The results validated the proposed mix design method that allowed a balance of physical, mechanical, and hydraulic properties to comply with requirements for field applications.