Effect of curing regime on the performance and microstructure characteristics of alkali-activated slag-fly ash blended concrete

The use of alkali-activated materials to produce concrete is a promising technology. However, information on the optimum curing regime required to maximize the performance of such concrete is lacking. This paper examines the fresh and hardened properties and microstructure characteristics of alkali-activated slag-fly ash blended concrete subjected to various curing regimes. Results showed that the optimum curing regime for alkali-activated blended concrete mixtures made with 0 and 25% fly ash was a combination of water and subsequent air curing, while that for mixes made with 50% fly ash was continuous water curing. Among these mixes, that incorporating 25% fly ash presented superior density, bulk resistivity, water absorption, compressive strength, and modulus of elasticity. Microstructure analysis revealed that the reaction products were an intermix of calcium aluminosilicate hydrate and sodium aluminosilicate hydrate. Analytical regression models were also developed to correlate the hardened properties of alkali-activated slag-fly ash blended concrete.