Synergetic effects of curing temperature and hydration reactivity of MgO expansive agents on their hydration and expansion behaviours in cement pastes. (20th May 2019)

• Record Type: Journal Article
• Authors: Mo, Liwu; Fang, Jianwei; Hou, Weihong; Ji, Xiankun; Yang, Jingbo; Fan, Taotao; Wang, Hailong
• Is Part Of: Construction & building materials. Volume 207(2019)
• Page Start: 206
• Page End: 217
• Publication Date: 2019-05-20
• Subjects: MgO expansive agent -- Expansion -- Curing temperature -- Hydration -- Microstructure; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.02.150
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: MgO with higher reactivity (MEA-R) produces more rapid expansion at early age. Curing temperature exhibits a synergetic effect on the hydration and expansion of MgO. Expansion of MgO with lower reactivity (MEA-M) is more sensitive to curing temperature. MEA-M produces larger ultimate expansions in long-term than MEA-R. Abstract: Effects of curing temperature on the hydration and expansion behaviours of MgO expansive agents with different reactivities in cement pastes were investigated via quantitative examination on the hydration degree of MgO, expansion, and microstructure of the cement pastes cured under various temperatures. Results reveal that reactive MgO with a reactivity value of 65 s (represented as MEA-R) produces more rapid and greater expansions than the less reactive MgO with a reactivity value of 145 s (MEA-M) at early age (within 28 d) and less expansions at late age under 20 °C. However, under higher temperatures (20 °C–80 °C) or at late age, the MEA-M produces larger expansions. The curing temperature has a synergetic influence on the hydration and expansion of cement pastes containing MgO expansive agents. MEA-M is more sensitive to the curing temperature as more considerable differences are caused among the expansions of cement pastes cured under different temperatures.