Effect of molarity in geopolymer concrete

Geopolymer Concrete (GPCs) is a new class of concrete based on an inorganic aluminosilicate binder system compared to the hydrated calcium silicate binder system of concrete. It possesses the advantages of rapid strength gain, elimination of water curing, good mechanical and durability properties and are eco-friendly and sustainable alternative to Ordinary Portland Cement (OPC) based concrete. In the construction industry mainly the production of Portland cement causes the emission of air pollutants which results in environmental pollution. This paper presents the details of the studies carried out on development of strength for various grades of geopolymer concrete with varying molarity. The alkaline liquids used in this study for the geopolymerization are sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃). Different molarities of sodium hydroxide solution (3M, 5M and 7M) are taken to prepare different mixtures. The test specimens were 150 x 150 x 150 mm cubes, 150 x 300mm cylinders prepared and ambient temperature curing conditions. The geopolymer concrete specimens are tested for their compressive strength at the age of 7 and 28 days. GPC mix formulations with compressive strength ranging from 15 to 52MPa have been developed. Experimental investigations have been carried out on workability, the various mechanical properties of GPCs. The test results indicate that the combination of fly ash and ground granulated furnace slag (GGBS) can be used for development of geopolymer concrete.