Mechanical and durability properties of basalt-steel wool hybrid fibre reinforced pervious concrete – A Box Behnken approach

The mechanical and durability properties of pervious concrete depend on void characteristics and the cementitious paste properties. The addition of fibers can improve the cementitious paste properties. However, a single fibre may not be competent to enhance the properties. Hence in the current study basalt-steel wool hybrid fibre system is used to improve the properties of pervious concrete. Box Behnken's design of experiments approach is used to generate higher order response surfaces using lesser number of trials. Cementitious paste volume, fibre volume, fibre volume ratio and coarse aggregate sizes are used as the response variables. The study is conducted on a total of 45 mix combinations. 5% silica fume is added to enhance the paste volume. To maintain the minimum void spaces, a cementitious paste volume of 20–40% is adopted. Total fibre addition in the range of 0–0.5% and basalt to steel wool hybridization ratio of 0–1 is maintained. Regression analysis is carried out to study the factorial level effects on both the fresh stage and hardened concrete properties. Fresh concrete properties like void ratio is increased and fresh concrete density is decreased with addition of fibres. The addition of fibres has slightly reduced the compressive strength. However, a substantial increase in flexural strength is found. Basalt rich pervious composites have an improved abrasion resistance. Increase in coarse aggregate size increased the fresh stage density and reduced the fresh stage void content of pervious concrete. Statistical analysis and prediction modelling are conducted to assure a match between the experimental values and the predicted values. •Pervious concrete is weak in mechanical properties.•The addition of hybrid fibres, basalt steel wool fibre, provides the synergistic effect of both fibres and improves properties in pervious concrete.•Macro fibres help to bridge cracks in concrete and enhance the strain hardening & flexural properties. Mono fibre addition enhances the flexural and tensile strength.•Box Behnken approach is used as a tool for reducing trials in experimentation.•Statistical analysis provide a relation between control factors and response variables.