Fly ash and ground granulated blast furnace slag-based alkali-activated concrete: Mechanical, transport and microstructural properties

Abstract

The present study optimizes various parameters such as ratio of alkali solution-fly ash, sodium silicate-sodium hydroxide, fine aggregates-total aggregates, sodium hydroxide concentration, total aggregate content and curing temperatures for the development of fly ash-based alkali-activated concrete using Taguchi method. Also, GGBS is included (0–20%) and further properties such as compressive strength, sorptivity, chloride permeability and microstructural properties of the resultant GGBS-based alkali-activated concrete are studied. Results showed the coexistence of calcium-based hydration products CSH and CASH along with the polymerization products NASH, making the matrix of alkali-activated binder more compact with lesser cracks and pore spaces. The above changes are also reflected in the increase observed in the compressive strength by approximately 52%, and the reductions in the sorptivity and chloride ion penetration by 35% and 78%, respectively, with increasing GGBS content from 0 to 20% in heat cured fly ash based alkali-activated concrete.