CO2 curing of SCMs blended cement blocks subject to elevated temperatures

• Published in: Construction & building materials Vol. 374; p. 130907
• Main Authors: Song, Qifeng, Guo, Ming-Zhi, Gu, Yue, Ling, Tung-Chai
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 17.04.2023
• Subjects: CO2 curing; Elevated temperatures; Sorptivity; Supplementary cementitious materials; Elevated temperatures; CO2 curing; Supplementary cementitious materials; Sorptivity
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.130907

[Display omitted] •SCMs pastes by CO2 and coupled CO2-standard curing were exposed to high temperature.•Coupled CO2-standard curing yielded the highest compressive strength at 600 ℃.•Coupled CO2-standard curing of SCMs pastes induced a denser pore structure at 600 ℃.•Glass powder barely showed pozzolanic reaction or carbonation promotion but was inert in cement blocks. This study seeks to understand the influence of CO2 curing on the high-temperature performance of cement paste incorporated with different types of common supplementary cementitious materials (SCMs). The results showed that due to the simultaneous generation of CaCO3 and hydration products, the samples carbonated for 2 days and then standard cured for 26 days (CS curing) had the best high-temperature resistance, which was reflected by higher compressive strength, lower water absorption and decreased water sorptivity. Interestingly, the porosity of the CS cured ground granulated blast furnace slag (GGBS)-incorporated cement block decreased by 26.80% after exposure to 600 ℃ due to the transformation of large loose pores into more compact small pores. Glass powder (GP) was inert in the paste matrix with no obvious pozzolanic reaction and negligible improvement of carbonation degree, leading to the lowest elevated-temperature performance; whereas, GGBS and fly ash (FA) increased the generation of CaCO3 by 19.05% and 15.08%, respectively. Overall, findings from the present study demonstrate that the employment of CS curing of SCMs blended cement blocks has great potential to reduce carbon footprint and improve performance under elevated temperatures.