Impact of limestone on hydration kinetics and strength development of low-clinker (

초록

This study investigates the effects of curing temperature (5, 25, and 40 ℃) and limestone incorporation (0, 5, 10, 15, and 20 wt%) on hydration and strength development in high-volume slag cement pastes. While plain ordinary Portland cement pastes exhibited a reduction in the ultimate hydration heat ( Q max ) at 40 ℃ compared with those cured at 25 ℃, slag-blended mixtures exhibited a continuous increase in Q max with temperature. Compared with the OPC-slag binary system, moderated limestone incorporation (5 wt%) at 5 and 25 ℃ enhanced slag hydration and reduced porosity, increasing 56-days compressive strength from 31 to 40 MPa and from 50 to 58 MPa, respectively, accompanied by an increase in the degree of reaction from 43% to 65% and from 60% to 68%. By contrast, at 40 ℃, Q max and compressive strength decreased with increasing limestone content, as limestone primarily acted as an inert filler. Overall, 5 wt% limestone incorporation effectively compensated for kinetically limited slag hydration at 5 and 25 ℃ despite the reduction in clinker factor from 50 to 45 wt%, whereas additional limestone incorporation became detrimental at 40 ℃.

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