Effect of calcined dolomite addition on sodium carbonate-activated slag cements with different curing methods

This paper reports the performances of sodium carbonate-activated slag cements incorporating calcined natural dolomite (CD) under sealed and ambient curing conditions. The reaction process, compressive strength development and microstructure characteristics are studied, as well as the carbonation behaviour of the samples under ambient curing conditions. The CD contents vary from 0 to 10% and the sodium carbonate contents are fixed at 5% and 10%. The results show that the reaction process can be significantly accelerated by adding a small quantity of CD. Both increasing the concentration of sodium carbonate and extending the sealed curing are proven to be beneficial to compressive strength development of the samples. The main reaction products in the binders are calcite, calcium silicate hydrates and hydrotalcite-like phases. The curing regimes have a negligible influence on the formation of those phases. In terms of carbonation, increasing either CD or sodium carbonate contents can restrict the extent of carbonation of the samples. This is attributed to the formation of large quantities of hydrotalcite-like phases in the binder.