期刊
CEMENT AND CONCRETE RESEARCH
卷 152, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.cemconres.2021.106674
关键词
Hydrotalcite; LDH; Magnesium; Anions; Thermodynamic data
资金
- European Union [662147]
Experimental observation showed that MgO in cementitious materials precipitates as poorly crystalline hydrotalcite, but the lack of consistent thermodynamic data for hydrotalcite makes geochemical modelling challenging. Synthesizing hydrotalcites with different anions indicated varying levels of crystallinity. The stability of hydrotalcite structure with temperature was found to depend on the incorporated anion.
MgO contained in cementitious materials is experimentally observed to precipitate as poorly crystalline hydrotalcite (Mg-Al LDH). However, the geochemical modelling of hydrotalcite is challenging due to the lack of consistent thermodynamic dataset for this phase. Hydrotalcites with Mg/Al = 2 were synthesised in the presence of NaHCO3, NaCl, Na2SO4, NaNO3, and NaOH. Mass balance, XRD and FT-IR indicated the incorporation of the anions in the interlayer together with some carbonate. The crystallinity of the phase increased depending on the anion: SO42- < Cl- < NO3- < OH- < CO32-. An in-situ increase of temperature monitored by XRD and TGA showed that the stability of the hydrotalcite structure with temperature also depended on the incorporated anion. The solubility products were calculated based on the solution analysis of samples re-equilibrated at different temperatures, while the entropy and heat capacity were obtained from the additivity method or the molar volume. A simple solid-solution model for hydrotalcite containing CO3, OH, SO4, Cl and NO3 is suggested.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据