Sulphuric acid resistant ecofriendly concrete from geopolymerisation of blast furnace slag

Abstract

In this study, geopolymer is prepared from ‘ground granulated blast furnace slag’ (GGBS)–a powder from grinding the by-product of slag waste from blast furnace of steel plants. For comparison, conventional cement, Portland pozzolana cement (PPC) containing fly ash was considered. To achieve simultaneous acidic and sulphate attack, sulphuric acid is used for durability studies. The test data indicate that on exposure to 2% and 10% sulphuric acids, the losses in weight, thickness and strength of geopolymer concrete (GPC) are significantly much less than those for Portland pozzolana cement concrete (PPCC). The GPCs have inorganic polymers of alumino-silicates as binder, generally without any free lime. Therefore, GPCs resist acid attack better than free lime containing conventional concretes containing Portland cement. The binding action in GPC is through geopolymerisation of GGBS using alkaline activator solution (AAS) made of sodium hydroxide and sodium silicate solutions. The geopolymer eliminates use of Portland cement in structural concretes by utilizing the industrial by-product GGBS, thereby reducing considerably the carbon footprint measured by ‘embodied energy’ and ‘embodied carbon’, i.e., ‘CO₂e emission’ of concrete.