Geo-polymer concrete- a concrete for sustainable environment

Abstract

The production of the cement concrete industry has grown in this modern world and is considered one of the major contributors to global pollution. The production of cement used as a binder in cement concrete requires a high-temperature combustion process which contributes to the increase of the amount of CO2 in the atmosphere leading to major threats to the planet such as climate change and depletion of natural resources. Many countries begin to impose carbon taxes as raw materials deplete over time. To reduce and eliminate greenhouse gas emissions, numerous studies have been conducted to develop an innovative and environmentally beneficial building material names Geo-polymer concrete (GC). It is vital to substitute cement with a by-product substance abundant in silicon and aluminium like red mud, fly ash (FA), rice husk ash (RHA), silica fume (SF), ground granulated blast furnace slag (GGBS), etc. activated by a high alkaline solution (AS) to connect coarse aggregates (CA), fine aggregates (FA), and other substance in GC for the purpose of making a progress in qualities of concrete and reduce natural resource uses. The current study focused on the impact of various factors such as the effect of superplasticizer, Na-OH molarity (8, 10, 12, 14 and 16M), and curing temperature (30-900C) on different mechanical characteristics such as workability, tensile and compressive strength of GC. Results obtained show that the higher strength is obtained with a molarity of 14M after both 7 and 28 days as with 16M excess Na+ ions lower the strength and affect the process of polymerisation. The curing temperature at 900C for all mixtures gives higher strength as compared to 600C which in return gives higher strength than 300C at 28 days of testing. The results also show that the addition of superplasticizer (1, 1.5, 2 and 3 % of mass of fly ash) improves the workability of geopolymer fresh concrete. In current research work, Naphthalene superplasticizer was used and its addition beyond 1.5% of the mass of fly ash improved workability but slightly decreased the strength of concrete. Its optimum value was found as 68.05KN/m2 at 900C curing temperature when 14M NaOH and 1.5% superplasticizer were added.