Properties of foundry sand, ground granulated blast furnace slag and bottom ash based geopolymers under ambient conditions

Abstract

This paper presents a feasibility study on the manufacture of geopolymer concrete at low concentrations of alkaline solutions and lower densities and incorporating waste products like Foundry sand without compensating for the strength properties. Ground Granulated Blast Furnace Slag (GGBFS) and Bottom ash (BA) were used as source materials. From the preliminary studies, the replacement of Foundry sand to Natural sand is taken as 50:50. The density range was taken as 1800 Kg/m3, 2000 Kg/m3, 2200 Kg/m3 and 2400 Kg/m3. Sodium Hydroxide(NaOH) and Sodium Silicate(Na2SiO3) were used as alkaline activators and the molarity of NaOH solution was reduced from 8M upto 4 M. The percentage ratio of BA-GGBFS was selected as 0, 25, 50, 75 and 100. The ratio of Alkaline liquid to Binder content was taken as 0.4 and the molar ratio of NaOH solution was kept as 1. The ratio of Sodium silicate solution to Sodium hydroxide was taken as 2. Ambient curing was adopted for all the mixes. The properties of Geopolymer concrete paver blocks such as Compressive strength, flexural strength and split tensile strength, water absorption, Acid attack and Water absorption were conducted as per IS 15658:2006. Test results show that satisfactory strength properties of geopolymer concrete using Foundry sand can be achieved even with lower concentrations of NaOH solution under ambient curing conditions. This would pave way for creating a greener environment by the efficient use of byproducts and waste materials in concrete.