Effect of fly ash on properties of Gap graded concrete

Gap graded concrete, also known as pervious concrete, or enhanced concrete, is a storm water drainage replacement. Pervious or porous concrete is a homogeneous mixture of cement, fine aggregates to some percent, coarse aggregate and admixtures with partial substitutes of fine aggregate. The particle sizes and proportions of the materials used indicate the value and permeability of this form of concrete. We addressed the strength parameters and permeability of this concrete with various aggregate sizes in this paper. The 70:30 coarse aggregate mix ratio is used. Two coarse aggregate mixes of 20–10 mm and 10–6 mm were used in this study for the different aggregate ratios. The larger the aggregate, the better the porosity for rainwater runoff and storage. To achieve better performance, 15% fly ash is used as a substitute for cement in the mix design in the experiments. The water binder ratio is kept constant at 0.38, while the cement to aggregate ratio is set at 1:5. The porous concrete moulds are cast and tested for mechanical and toughness properties. For the above-mentioned tests, cubes, tubes, and beams are casted.