Effect of substitution of granulated slag by air-cooled slag on the properties of alkali activated slag

This article assesses the mechanical and durability performance of replacement of GBFS by ACS activated by 3:3 NaOH:Na2SiO3 (3:3 SH:SSL) wt% (at optimum value 6 wt%) mixed with sea water (SW) and cured at 100% R.H. at room temperature. The kinetic behavior of activated GBFS-ACS mixes was measured by determination of setting time, combined water, bulk density and compressive strength up to 90 days. The rate of activation of the AAS has been studied from some selected samples by FT-IR, TGA, DTG analysis and SEM techniques. The compressive strength of dried activated GBFS-ACS pastes in comparison with saturated GBFS-ACS pastes up to 90 days was determined. The results revealed that the blended pastes of 80% GBFS+20% ACS gives the higher combined water, bulk density and compressive strength than those of 40/60 and 60/40% GBFS/ACS and lower than the 100% GBFS up to 90 days. Also, the compressive strength of dried samples at 105 °C for 24 h activated by (3:3 SH:SSL) mixed with SW and cured in 100% R.H. at room temperature up to 90 days is greater than saturated samples cured at the same conditions. On increasing the amount of ACS up to 40%, the setting time decreases then increases at 60% but still shorter than 100% GBFS. Finally, ACS can be used as partial substitution of GBFS in AAS.