Synergistic effect of metakaolin and limestone on the hydration properties of Portland cement

The effects of simultaneous addition of limestone and metakaolin with different mass ratio on the hydration of Portland cement are investigated by a multi-method approach. The results indicate that the strengths of Portland cement mortars are depended on the mass ratio of metakaolin to limestone. When the ratio is as high as 1:2, the strengths of the blends are higher than those of Portland cement. The mixture of metakaoin and limestone stimulates the hydration of C₃S and the formation of ettringite. The synergistic effect of MK and LS refined the pore distribution by consuming portlandite during the hydration. By incorporation metakaolin, hemicarboaluminate still exists in the late hydration, the hemicarboaluminate increases as the amount of metakaolin increases.