Preparation of Nano Calcite by the Carbon Capture Technology to Improve the Performance of Ultrahigh-Performance Concrete Containing Calcined Clay
Yi Han, Run-Sheng Lin, Xiao-Yong Wang
Abstract
Ultrahigh-performance concrete (UHPC) has been widely used because of its outstanding mechanical properties and durability. However, the high demand for cement leads to higher carbon dioxide emissions. In this study, solid nano-calcium carbonate (nano-CaCO 3 ) derived from gaseous carbon dioxide is used as an admixture to UHPC, which indirectly realizes the capture and storage of carbon dioxide by UHPC. This study investigated the effect of the nano-CaCO 3 on the macroscopic and hydration properties of the UHPC, characterized its microstructure, and calculated the carbon dioxide emission. The experimental and analytical results show that the mechanical properties and durability of the UHPC are significantly improved with the nano-CaCO 3 addition. Microscopic experimental analysis reveals that the presence of nano-CaCO 3 significantly increases the hydration rate of the mixture. During the middle and late stages, the nano-CaCO 3 reacted with the aluminum in Hwangtoh clay to form monocarboaluminate, which made the UHPC internal structure denser. Furthermore, the calculation results show that the nano-CaCO 3 has a significant effect on reducing the UHPC CO 2 emission, owing to the CO 2 capture and sequestration during the conversion of gaseous CO 2 into solid nano-CaCO 3 .