Double-sided tuning effects of lactic acid on the hydration, microstructure and strength of supersulfated cement

Abstract

In this study, hemihydrate gypsum was employed to produce supersulfated cement (SSC), and lactic acid was used to address the poor workability induced. The results indicated that lactic acid significantly improved the fluidity and setting time of SSC. In addition, lactic acid exerted a double-sided tuning effect on the hydration process of SSC. At the early stage, the hydration heat release decreased and fewer hydration products were generated, which led to a lower mortar strength. However, a greater number of hydration products formed after long-term curing that included a compact microstructure with less porosity, which contributed to the strength. This was attributed to the higher hydration degree of slag caused by chelation with lactic acid. Overall, SSC mixtures with moderate lactic acid content can obtain desirable properties in terms of both early-stage workability and long-term strength. The findings of this study facilitate a broader design and application of SSC mixtures.

Keywords:

• Supersulfated cement
• lactic acid
• hydration mechanism
• microstructure
• hemihydrate gypsum

Acknowledgements

The authors acknowledge support from the National Natural Science Foundation of China (Grant Nos.: 52050128, 51908119, 6512009004A, and U1706222), the Natural Science Foundation of Jiangsu Province (Grant No.: BK20190367), the 2021 High-level Personnel Project Funding of Jiangsu Province(JSSCBS20210151), and the financial funding of Shandong High Speed Group Co., Ltd. Also, we would like to thank Editage (www.editage.cn) for English language editing.

CRediT authorship contribution statement

Yang Zhou: Conceptualization, Data curation, Formal analysis, Investigation, Writing—Original Draft. Zechuan Peng: Conceptualization, Methodology, Formal analysis, Funding acquisition, Writing—Review & Editing. Luchuan Chen: Conceptualization, Validation, Writing—Review & Editing. Disheng Xu: Methodology, Investigation, Writing—Review & Editing. Hao Wang: Methodology, Visualization, Writing—Review & Editing.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.