Abstract
Activated calcium carbonate (a-CaCO3) is used partially to replace Portland cement. a-CaCO3 is comprised of nanoscale calcium carbonate, in amorphous and calcite forms, and its enhanced carbonate activity converts calcium carbonate from being an inert filler to a reactive component. Its reaction with the C–S–H phase alters the conventional hydrate mineralogy with spontaneous formation at ∼20 °C of scawtite, Ca7(Si6O18)CO3·2H2O and tilleyite, Ca5Si2O7(CO3)2. Compressive strength measurements show that up to 20 mass% cement replacement by calcium carbonate does not decrease 7- and 28-day compressive strengths compared to a Portland cement benchmark. a-CaCO3 also accelerates the hydration of silicate clinker minerals. Using activated calcium carbonate as a supplementary cementing material enables substantial reduction of CO2 emissions, firstly by capturing part of the CO2 from cement kilns to make nanoscale calcium carbonate and secondly, by using the a-CaCO3 capture product to replace part of the cement.
Original language | English |
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Article number | 103906 |
Number of pages | 12 |
Journal | Journal of Building Engineering |
Volume | 48 |
Early online date | 17 Dec 2021 |
DOIs | |
Publication status | Published - 1 May 2022 |
Keywords
- Calcium carbonate
- Carbon capture and use (CCU)
- Cement mineralogy
- Circular economy
- Portland cement