A comparative study of alkali activated slag cement concretes with carbonate and silicate activators.

Alkali-activated cements are increasingly gaining interest as viable alternatives to Portland cement, because they are considerably reducing CO2 emissions compared to traditional Portland cements while maintaining or exceeding performance requirements commonly specified for construction applications. Experience of this type of cement shows that the results are very sensitive to mixing procedures and curing conditions. This article thus studies concretes with Na2CO3 activated ground granulated blast furnace slag (GGBS) cement mixes and mixes of on Na2CO3 plus Na2SiO3 activated GGBS under different mixing and curing regimes. After studying different mixing procedures of the ingredients and their effects on the compressive strength, the most suitable mixing procedures were adopted for a series of mechanical and durability related tests using different curing conditions. The results showed that providing the carbonate in solution rather than powder form, resulted in higher strengths. Curing conditions at ambient temperature and high humidity regimes were most successful in maintaining strength development in time. All mixes had adequate strengths for structural concrete but those with Na2SiO3 developed the highest strengths at all ages and curing conditions.