Early-age carbonation mitigation of SSC by CxS minerals: Mechanism and Performances

• Published in: Construction & building materials Vol. 430; p. 136391
• Main Authors: Wang, Jixiang, Li, Xiang, Sun, Rui, Zhao, Yuxi, Gong, Fuyuan, Huang, Tianyong, Liu, Ze, Wang, Dongmin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 07.06.2024
• Subjects: Calcium silicate minerals; Carbonation; Mitigation; Supersulfated cement; Mitigation; Carbonation; Calcium silicate minerals; Supersulfated cement
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.136391

The absence of portlandite and lower alkalinity in the supersulfated cement (SSC) system make it sensitive to being carbonated, especially, since the early-age carbonation would suppress the further hydration of SSC and its performance development. Here, the low-calcium silicate minerals (CxS, hydration active or non-active) were used as carbonation mitigation agents and were systematically investigated for their effects on SSC carbonation. It was found that hydration active minerals – C3S2 and β-C2S present negative effects no matter on the hydration and carbonation mitigation aspects due to the more reactive hydraulic minerals would suppress the hydration of slag itself and thereby lowed the hydration degree of SSC. For non-hydration active minerals, α-CS polymorphs have little effect on the hydration of SSC. Unfortunately, they are carbonation unactive in the SSC system, and negative for mitigation of carbonation either. Only β-CS and γ-C2S are valid in mitigation carbonation of SSC with reasonable content (for β-CS over 20 wt% and γ-C2S over 10 wt%). The incorporation of high-carbonation activity minerals maintained the integrity of hydrates in SSC and reduced the porosity of the carbonated matrix mainly by scarifying themselves to carbonation and protect the hydrates, as consequence, mitigating the carbonation and favoring the strength maintenance of SSC. •The carbonation performances of supersulfated cement (SSC) have been systematically investigated.•A new scarifying protection carbonation mitigation strategy for SSC has been present.•Hydraulic non-hydraulic calcium silicates minerals were used for mitigate carbonation of SSC.