The C-S-H gel of Portland cement mortars: Part I. The interpretation of energy-dispersive X-ray microanalyses from scanning electron microscopy, with some observations on C-S-H, AFm and AFt phase compositions |
| |
Authors: | C. Famy A.R. Brough |
| |
Affiliation: | a Lafarge, Laboratoire Central de Recherche, 38291 Isle d'Abeau, France b CEMU, Departments of Civil Engineering and Materials, University of Leeds, Leeds LS2 9JT, UK c Maundry Bank, Lake Road, Coniston, Cumbria LA21 8EW, UK |
| |
Abstract: | Scanning electron microscopy (SEM) microanalyses of the calcium-silicate-hydrate (C-S-H) gel in Portland cement pastes rarely represent single phases. Essential experimental requirements are summarised and new procedures for interpreting the data are described. These include, notably, plots of Si/Ca against other atom ratios, 3D plots to allow three such ratios to be correlated and solution of linear simultaneous equations to test and quantify hypotheses regarding the phases contributing to individual microanalyses. Application of these methods to the C-S-H gel of a 1-day-old mortar identified a phase with Al/Ca=0.67 and S/Ca=0.33, which we consider to be a highly substituted ettringite of probable composition C6A2S?2H34 or {Ca6[Al(OH)6]2·24H2O}(SO4)2[Al(OH)4]2. If this is true for Portland cements in general, it might explain observed discrepancies between observed and calculated aluminate concentrations in the pore solution. The C-S-H gel of a similar mortar aged 600 days contained unsubstituted ettringite and an AFm phase with S/Ca=0.125. |
| |
Keywords: | Hydration Early product Calcium-silicate-hydrate (C-S-H) Ettringite EDX |
本文献已被 ScienceDirect 等数据库收录! |
|