EFFECT OF TEMPERATURE, ALKALI AND ALUMINIUM ON CALCIUM ALUMINOSILICATE HYDRATE CHEMISTRY UNDER EQUILIBRIUM CONDITIONS
Little is known about the effect of temperature on the structure and stability of calcium-alkali aluminosilicate hydrate (C-(N)-A-S-H) and calcium aluminosilicate hydrate gels,which are the main reaction products in Ca-rich alkali-activated binders and in Portland cement (PC) blends with high replacement levels of supplementary cementitious materials.Here,C-(N)-A-S-H type products are synthesised from laboratory-grade reagents at Ca/Si =1,Al/Si =0 and 0.05,NaOH concentrations up to 0.5 M,and equilibrated at 7℃,20℃ and 50℃.The long-range order of the C-(N)-A-S-H type phase increases with temperature and alkali concentration.Katoite and str(a)tlingite are formed at 7℃ in the Al/Si =0.05,alkali-free system; small amounts of katoite are also present in the Al/Si =0.05,0.5M NaOH samples at 20℃ and 50℃.Decreased dissolved Al and Si concentrations,and increased Ca concentration,are observed from 7℃ to 50℃ for the alkali-containing systems.A reduction in Al concentration,a small increase Si concentration and little change in dissolved Ca content is found for the alkali-free samples over this temperature range.These results are important in the thermodynamic modelling of Ca-rich alkali-activated binders and blended PC systems,to enable improvement of how these materials are understood to perform in service.
hydration products calcium silicate hydrate (C-S-H) temperature alkalis
Rupert J.Myers Emilie LHopital John L.Provis Barbara Lothenbach
Department of Materials Science and Engineering,University of Sheffield,Sheffield,UK;Laboratory for Laboratory for Concrete and Construction Chemistry,EMPA,Dübendorf,Switzerland Department of Materials Science and Engineering,University of Sheffield,Sheffield,UK
国际会议
长沙
英文
225-231
2014-06-01（万方平台首次上网日期，不代表论文的发表时间）