Effect of Pore Structure and Ion Concentration of Solution on the Formation of Ettringite in Composite Cement Paste

Abstract:

Under the background of shrinkage cracking of cement and concrete, ettringite is regarded as the most effective expansion source because of its outstanding expansion characteristics. In order to study the expansion mechanism of ettringite, the growth process and formation conditions of ettringite in composite cement system were studied by means of SEM, MIP and ICP. The effects of pore structure and ion concentration of pore solution on the morphology and expansion properties of ettringite were also analysed in this paper. The results show that the pore structure of cement paste directly affects the expansion properties of ettringite. It is verified that there is no obvious linear relationship between the expansion rate of ettringite and its quantity. The concentration of SO₄^2- and Al(OH)₄^- in pore solution is the determinant of ettringite formation rate and quantity in composite cement system at the initial stage of hydration reaction. The change of crystallinity of ettringite will be directly caused by pH.

• Periodical: Materials Science Forum (Volume 993)
• Pages: 1382-1387
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.993.1382
• Online since: May 2020
• Authors: Yan Zheng*, Su Ping Cui
• Keywords: Composite Cement, Ettringite, Microstructure, Pore Solution, Pore Structure

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