Effects of cement types and addition of quartz and limestone on the normal and carbonation curing of cement paste

초록

Belite-rich cement (BRC) and carbonation curing are vital in the cement and construction industries for reducing carbon emissions and achieving carbon neutrality. In this study, the effects of quartz, limestone, and the type of cement (BRC and ordinary Portland cement) on the carbonation curing and normal curing of cement paste were systematically studied. The water/binder ratio was 0.5, and the replacement ratio of quartz/limestone was 20%. The experimental results showed that adding 20% quartz/limestone to BRC effectively accelerated the carbon-ation curing process, and the acceleration effect of quartz was more obvious than that of limestone. The compressive strength of the samples with 20% quartz and limestone added to BRC was 72 MPa and 69 MPa, respectively, after 28 days of carbonation curing. These are respectively 1.7 times and 1.6 times higher than the compressive strength of the samples under normal curing. The late-age strength mainly depended on the amount of cement and marginally depended on the addition of quartz/limestone. Quartz improved carbonation efficiency by increasing the porosity of the cement paste and providing nucleation sites for the silica gel formed during carbonation. Moreover, CH, ettringite, monocarboaluminate, and hemicarboaluminate were fully carbonated, and large amounts of alite and belite were carbonated during carbonation curing. The electrical resistivity after 28 days of carbonation curing was 38-72 times higher than its electrical resistivity after 28 days of normal curing. After carbonation curing, the quartz-blended BRC had a high resistivity of 1562 k omega.cm. Thus, quartz is an effective supplementary material for the carbonation curing of concrete. Moreover, the combination of quartz and BRC has a greater impact on carbonation curing than the combination of limestone and BRC.

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