Studies of portions of the quaternary system soda-lime-silica-water at 25 degrees C

Abstract

A study has been made of portions of the system soda-lime-silica-water at 25° C. The only solid phases found were Ca(OH)2 and a four-component gel of variable composition. The boundary, Ca(OHh-soda-lime-silicate gels, was determined and the compositions of the gels along this boundary shown to vary from 0.003Na20:2.OCaO: 1.0Si02 :xH20 (at 0.2 g of Na20 per liter) to about 0.25Na20:-1.0CaO: 1.0Si02 :xH20 (at 20 g per liter and extending to 101 g per liter of Na20). In regions off the boundary, at selected constant concentrations of Na20 but with increasing concentrations of Si02 in solution, the Na20:Si02 molar ratio of the gels varied only slightly from 0.2 in most cases; the CaO: Si02 molar ratio, however, decreased to values approaching 0.1 at the maximum concentrations of Si02 used. Interpretations pertaining to relations between the composition of the gels and solutions are given.

Solubility and structure of calcium silicate hydrate

“…Moreover, the trends in Figure 2 show that, at a given Ca/Si ratio, samples of the double decomposition group have higher Ca and lower Si concentrations in the aqueous phase than those of the C 3 S group. If contamination by alkali were the cause of the differences between the two groups, these trends would be reversed [60,61].…”

Composition–solubility–structure relationships in calcium (alkali) aluminosilicate hydrate (C-(N,K-)A-S-H)

“…19 The essentially aluminium-free C-(N,K-)S-H formed during plain Portland cement hydration can incorporate a significant content of alkalis (up to 20% of the amount of Na or K added 21 ), which decreases as a direct function of the Ca/Si ratio. 21 A good understanding of C-(N,K-)S-H solubility currently exists up to bulk Na concentrations of 0.8 M NaOH, 8,9,[21][22][23][24] which represents the pH range relevant to most cement-based materials ( pH ≤ 13.5), but fewer solubility data for this phase are available for K-containing materials in the corresponding composition range. 21,22,25,26 These data are essential in understanding the long-term stability of C-(N,K-)-S-H and in the development of thermodynamic models for this phase, enabling simulation of the chemistry of cementbased materials in service.…”

Investigation for Reaction Mechanism of Nano-Silica-Modified Cement-Based Composite Materials

“…That make aperture diffusion reduce, the C-S-H(CxSHx -0.5)gel are dense twisted with ettringite; the pore space structure is more sharped, The surface is became smooth, hexagonal prism calcium aluminate hydrate and particle clound forest shape C-S-H gel are mutual overlapped, twisted, Its looks like the stone striatum structure. So that, the cement mortar structure is more dense, because the nano-silica has good dispersivity, It make the harden cement mortar total pore space ratio reduce, The cement mortar structure became more dense, Its strengths are more evident high than the same age no modified harden cement mortar [12][13][14][15][16].…”