Effect of Magnesium Carbonate on Hydration and Hardened Properties of Portland Cement Paste
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-2292-3
Structural Engineering
Effect of Magnesium Carbonate on Hydration and Hardened Properties of Portland Cement Paste Fanghui Lia, Zuqiang Xiongb, Cheng Wangb, and Yuli Wanga a Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China b School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, China
ARTICLE HISTORY
ABSTRACT
Received 12 December 2019 Revised 13 March 2020 Accepted 12 July 2020 Published Online 24 September 2020
The effects of magnesium carbonate on the setting time and compressive strength of Portland cement paste were studied when the content of magnesium carbonate was 0wt%, 0.5wt%, 1wt%, 2wt%, and 3wt% by the weight of cement. The influence mechanism was analyzed through combining with the tests of hydration heat, X-ray diffraction (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG), and scanning electron microscope (SEM). The results show that magnesium carbonate makes the setting time of cement paste shorten, and makes the compressive strengths of cement paste increase at 1 day and 7 days, but decrease at 28 days. The testing results of the heat of hydration, XRD, SEM, and DTA-TG show that magnesium carbonate promotes the formation of Ettringite (AFt) and the hydration of calcium silicate in the early stage when its content is less than 1wt%, but the addition of magnesium carbonate is unfavorable to the later hydration of Portland cement. Based on the above analysis, it is suggested that the content of magnesium carbonate is not more than 1wt%, which has good reference value for using magnesium carbonate to prepare early strength agent for cement paste.
KEYWORDS Magnesium carbonate Portland cement Compressive strength Setting time Early strength agent
1. Introduction The greenhouse effect is a significant environmental problem. Carbon dioxide is the main greenhouse gas that causes the greenhouse effect (Solomon et al., 2009). The situation of emission reduction is grim (Lim et al., 2010), about 5% of the world's annual carbon dioxide emissions comes from the cement industry (Worrell et al., 2001). Measures should be taken from the firing stage and the use stage respectively (Chan et al., 2015). Some experts through the analysis of carbon dioxide cycle chain (Zhang et al., 2013), found that cement and concrete can be used to carbon sequestration (El-Hassan and Shao, 2014), not only meet the emission reduction requirements but also meet the economic benefits (Marzi et al., 2018). Some scholars have found that some carbonates can promote early hydration of cementbased materials (Zhang et al., 2018). Much research on the use of carbon dioxide in cement-based materials has been reported, and it can be roughly divided into three research directions: the use of
CORRESPONDENCE Yuli Wang [email protected] Henan Polytechnic University, Jiaozuo 454003, China ⓒ 2020
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