Shrinkage and carbonation of alkali-activated calcined clay-ground granulated blast furnace slag (GGBFS) concrete
Samuel De Carvalho Gomes, Quang Dieu Nguyen, Wengui Li, Arnaud Castel
Abstract
This research investigates the influence of alkaline concentration and calcium content on the shrinkage mechanisms, carbonation resistance and reinforcement corrosion of alkali-activated concrete system composed of calcined clay and ground granulated blast furnace slag (GGBFS). An increase in Na 2 O% led to an improvement in the mechanical performance, pore structure refinement, reducing both accelerated and natural carbonation. However, the increase in alkaline concentration generated a greater shrinkage for mixtures with a higher proportion of GGBFS; the opposite was observed for mixtures with calcined clay as the dominant precursor. The results of 1-year of total shrinkage shows that the concrete containing high calcined clay and Na 2 O contents demonstrated the best performance. Importantly, there was no evidence of reinforcement corrosion observed after the carbonation front had reached the steel-concrete interface following 2 % CO 2 accelerated carbonation exposure. This was attributed to the high pH values measured in the carbonated region of the alkali-activated concrete.