Combined effect of lignosulfonate and carbonate on pure portland clinker compounds hydration. V. Hydration of dicalcium silicate alone and in the presence of tricalcium aluminate

The effect of sodium carbonate and/or sodium lignosulfonate on the hydration of C₂S alone and in the presence of C₃A has been examinated by DTG and TG curves and by zeta potential measurements. The combined addition of sodium carbonate and lignosulfonate retards the C₂S hydration to a lower extent than that observed for the C₃S hydration. The retarding effect on the C₂S hydration is significantly lower in the presence of 20% C₃A. On the other hand, the early C₃A hydration is completely blocked by admixtures simultaneously added. Addition of 0.9% sodium carbonate without lignosulfonate blocks the early hydration of both C₃A and C₂S. This effect was not found in the C₃SC₃A system.