Properties of Metakaolin Based Pervious Geopolymer Concrete

Abstract

Utilizing Geopolymer binder instead of Portland cement in pervious concrete or ordinary concrete is the one solution toward reducing emission of carbon dioxide in the environment. Metakaolin (MK) used as a binding material to produce Pervious Geopolymer Concrete (PGC) in this investigation. Different PGC mixes were prepared and their, density, void content and compressive strength were tested. The effects of different proportions of alkaline liquid to metakaolin ratio AL/MK (0.5, 0.55 and 0.6); metakaolin to coarse aggregate MK:CA ratio (1:5, 1:6 and 1:7); superplasticizer dosages (0, 1, 2 and 3% by weight of MK); and the effect of using a fine aggregate at levels of 5 and 10% by weight of coarse aggregate were investigated. Sodium hydroxide (NaOH) having a concentration of 12 molarity with sodium silicate (Na2SiO3) to (NaOH) ratio of 2 are used as an alkaline activator to produce all PGC mixes. All PGC specimens cured at elevated temperature of 50°C for five hours after 24 hours of casting and tested after 7 days. The Results show that the optimum AL/MK ratio and superplasticizer dosage were 0.6 and 2% respectively. The compressive strength and oven-dry density were increased by about (19%, 20% and 32%) and (4.5%, 7.2% and 5.2%) for 1:5, 1:6 and 1:7 MK:CA ratio, respectively, while porosity was decreased up to 18% with the inclusion of 10% fine aggregate by weight of coarse aggregate.