Experimental study on mechanical and hydraulic properties of porous geopolymer concrete

Abstract

Normal porous concrete is a special type of concrete with high porosity, allowing water to percolate into the sub-grade, but using Portland cement. On the other hand, geopolymer concrete is an environmentally friendly concrete using fly ash, blast furnace slag and kaolinite alkaline activator. This experimental study proposes a fabrication procedure to combine the two above-mentioned concrete types to produce a sustainable material-porous concrete made of fly ash-based geopolymer with alkaline activators. Various parameters affecting the compressive strength, such as aggregate size, the water-to-(fly ash and blast furnace slag) ratio, the concentration of alkaline activator have been studied, together with two major hydraulic properties such as water permeability and porosity. The results show that the porous geopolymer concrete using local fly ash and blast furnace slag can achieve the compressive cube strength greater than 23MPa and the average values of water permeability are in the range of 6.4 to 17.8 mm/s depending on the mix design. Increasing coarse aggregate size increases the porosity and water permeability, however, lowers the compressive strength of porous geopolymer concrete. Increasing the activator-to-binder ratio, the compressive strength increases, not affecting the porosity and water permeability.