Hydration behavior and strength development of supersulfated cement prepared by calcined phosphogypsum and slaked lime
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2023-11-09
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Elsevier
Abstract
The effect of the content of calcined phosphogypsum (CPG) and slaked lime (SL) on the fluidity, setting time, and compressive strength of supersulfated cement (SSC) were investigated. The hydration mechanism of the SSC containing CPG and SL was examined through electrical resistivity, hydration heat, and chemical shrinkage measurements and thermodynamic modelling was performed to predict the phase assemblages. The results indicate that SSC with CPG delayed the early age hydration and prolongs its induction period. The effect of CPG on delaying hydration was apparent in SSC with 5 % SL. CPG in SSC promotes the formation of ettringite (AFt), while excess SL inhibits it. With the increase of CPG, massive gypsum is produced, leading to the rapid setting and a decrease in fluidity. Excess AFt contributes to expansion and cracking, resulting in a decrease in compressive strength. With the incorporation of SL, the pH value of the pore solution increases, which is beneficial to the stabilization of AFt, thereby increasing the compressive strength. The compressive strength of SSC containing 10 % CPG and 10 % SL reached up to 35.2 MPa after 180 d. The study reveals the mechanism of the effect of CPG and SL on SSC hydration and provides theoretical guidance for preparing SSC for engineering applications.
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This is a manuscript of an article published as Liao, Yishun, Jinxin Yao, Fang Deng, Hao Li, Kejin Wang, and Shengwen Tang. "Hydration behavior and strength development of supersulfated cement prepared by calcined phosphogypsum and slaked lime." Journal of Building Engineering (2023): 108075. doi:https://doi.org/10.1016/j.jobe.2023.108075. Posted with Permission. Copyright © 2023 Elsevier B.V. CC BY-NC-ND