Journal ArticleDOI
The hydration of tricalcium silicate in the presence of colloidal silica
Zhao-Qi Wu,J. F. Young +1 more
TLDR
In this paper, the reaction of colloidal silica fumes with calcium hydroxide or hydrating tricalcium silicate (C3S) has been studied using calorimetry, chemical analyses, and scanning electron microscopy.Abstract:
Reactions of colloidal silica fumes with calcium hydroxide or hydrating tricalcium silicate (C3S) have been studied using calorimetry, chemical analyses, and scanning electron microscopy. Silica fume reacts immediately with calcium hydroxide forming a colloidal calcium silicate hydrate (C-S-H) similar to that formed by the hydration of C3S. When excess silica is present it reacts with C-S-H already formed to produce a new, highly polymerized C-S-H, having a very low C/S ratio (1.0). Silica fume accelerates the hydration of C3S, reduces the amount of calcium hydroxide formed by reacting with it, and slightly lowers the C-S-H ratio of the C-S-H formed by hydration. When large amounts of silica fume are present the formation of calcium hydroxide may be entirely suppressed and a highly polymerized C-S-H is formed. Silica fume is considered a good model for reactive pozzolans used in concrete.read more
Citations
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Journal ArticleDOI
Mechanisms of cement hydration
Jeffrey W. Bullard,Hamlin M. Jennings,Richard A. Livingston,André Nonat,George W. Scherer,Jeffrey Schweitzer,Karen Scrivener,Jeffrey J. Thomas +7 more
TL;DR: The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period as mentioned in this paper.
Journal ArticleDOI
Degree of hydration and gel/space ratio of high-volume fly ash/cement systems
TL;DR: In this article, the degree of hydration of the cement in Portland cement (PC) paste was obtained by determining the non-evaporable water (Wn) content of the fly ash.
Journal ArticleDOI
Impact of admixtures on the hydration kinetics of Portland cement
TL;DR: In this paper, the impact on hydration of several classes of chemicals is reviewed with an emphasis on the current understanding of interactions with cement chemistry, including setting retarders, accelerators, and water reducing dispersants.
Journal ArticleDOI
Modification effects of colloidal nanoSiO2 on cement hydration and its gel property
Pengkun Hou,Pengkun Hou,Shiho Kawashima,Deyu Kong,Deyu Kong,David J. Corr,Jueshi Qian,Surendra P. Shah +7 more
TL;DR: In this article, the effects of colloidal nanoSiO2 (CNS) on cement hydration and gel properties in the early and later age, hydration heat, calcium morphology, hydroxide content, non-evaporable water (NEW) content and nanoscale mechanical properties were measured.
Journal ArticleDOI
Computer simulation of the diffusivity of cement-based materials
Edward J. Garboczi,Dale P. Bentz +1 more
TL;DR: In this paper, a digital image-based model of the microstructure of Portland cement paste, coupled with exact transport algorithms, is used to study the diffusivity of cement paste.
References
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Journal ArticleDOI
Influence of silica on the hydration of 3 CaO,SiO2
H. N. Stein,J. M. Stevels +1 more
TL;DR: Amorphous silica accelerates the hydration rate of 3CaO,SiO2 in Portland cement pastes by lowering calcium and hydroxyl-ion concentrations during the first minutes of hydration.
Journal ArticleDOI
Hydraulic cement pastes: Their structure and properties: Cement and concrete Association, Slough, England, 1976. Paperback, 334 pages, £9.
Journal ArticleDOI
Silicate polymerization during the hydration of alite
J. Hirljac,Z.-Q. Wu,J.F. Young +2 more
TL;DR: The influence of admixtures and curing temperature on silicate polymerization during the hydration of alite was studied in this paper, where the major species identified in the hydrated pastes were dimer, linear pantamer, and linear octamer; at later ages, particularly at higher temperature, higher polymers are formed.
Journal ArticleDOI
The tricalcium silicate hydration in the presence of active silica
TL;DR: In this paper, the influence of active silica upon tricalcium silicate hydration was studied and it was shown that the quasi-stationary layer supersaturated with calcium ions surrounding the anhydrous grains of trical calcium silicate is the delaying factor of C3S hydration process.
Journal ArticleDOI
The effect of pulverised-fuel ash on the c/s molar ratio and alkali content of calcium silicate hydrates in cement
TL;DR: In this paper, the effect of pulverised fuel ash on the C/S molar ratio and alkali content of calcium silicate hydrates in cement has been investigated by electron microprobe analysis.