Mechanical properties of porous concrete with variations of coarse aggregate gradation

Porous concrete is an innovation in sustainable concrete technology, which has high porosity concrete without fine aggregate. Porous concrete used in rain gardens, planter boxes, permeable pavements at urban open spaces could absorb rainwater so it can reduce run-off. This experimental study purposes to determine the compressive, split-tensile, flexural strengths, and permeability of porous concrete with various gradation of coarse aggregates. This study used a concrete mixture with coarse aggregate gradation variations of gap, continuous, and uniform on the water cement ratio of 0.4. The test specimens used three cylinders of 15x30cm for compressive and split-tensile strengths, except for uniform gradations used three cylinders of 10x20cm. Beam specimens of 15x15x60cm used for bending strength test by third point loading method. The tested mechanical properties are 7, 14, and 28 days-compressive strengths, 28 days split-tensile strength, and 28 days bending strength. The experimental results also show the average compressive strengths of porous concrete with variation of gradations of gap, continuous, and uniform for 28 days is 14.6 MPa, 13.0 MPa, and 10.6 MPa, respectively. Volumetric flow rate of porous concrete with gap, continuous, and uniform aggregate gradations is 28.4 ml/s, 32.1 ml/s, and 39.3 ml/s, respectively. The experimental results show that gap gradation is recommended due to its better compressive and flexural strengths. In porous concrete, aggregate gradations influence the air content. The highest air content results the lowest compressive strength of concrete. The designed air content should be controlled to maintain the expexted compressive strength of porous concrete