Silicate Hydrate (silicate + hydrate)

Distribution by Scientific Domains

Kinds of Silicate Hydrate

  • calcium silicate hydrate


  • Selected Abstracts


    Hierachically Nanostructured Mesoporous Spheres of Calcium Silicate Hydrate: Surfactant-Free Sonochemical Synthesis and Drug-Delivery System with Ultrahigh Drug-Loading Capacity

    ADVANCED MATERIALS, Issue 6 2010
    Jin Wu
    Ultrahigh drug-loading capacity and the linear relationship between the cumulative amount of released drug and the natural logarithm of release time were discovered for the hierachically nanostructured mesoporous spheres of calcium silicate hydrate (CSH) obtained by a surfactant-free sonochemical method (see figure). During the release of loaded ibuprofen in simulated body fluid, CSH gradually transformed to hydroxyapatite. [source]


    A Molecular Dynamic Study of Cementitious Calcium Silicate Hydrate (C,S,H) Gels

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007
    Jorge S. Dolado
    In this article, we study the polymerization of silicic acids (Si(OH)4) in the presence of calcium ions by molecular dynamics simulations. We focus on the formation and structure of cementitious calcium silicate hydrate (C,S,H) gels. Our simulations confirm that, in accordance with experiments, a larger content of calcium ions slows down the polymerization of the cementitious silicate chains and prevents them from forming rings and three-dimensional structures. Furthermore, by an analysis of the connectivity of our simulated silicate chains and by a count of the number of Ca,OH and Si,OH bonds formed, the relationship with commonly used structural models of C,S,H gels, such as 1.4 nm tobermorite and jennite, is discussed. [source]


    Hierachically Nanostructured Mesoporous Spheres of Calcium Silicate Hydrate: Surfactant-Free Sonochemical Synthesis and Drug-Delivery System with Ultrahigh Drug-Loading Capacity

    ADVANCED MATERIALS, Issue 6 2010
    Jin Wu
    Ultrahigh drug-loading capacity and the linear relationship between the cumulative amount of released drug and the natural logarithm of release time were discovered for the hierachically nanostructured mesoporous spheres of calcium silicate hydrate (CSH) obtained by a surfactant-free sonochemical method (see figure). During the release of loaded ibuprofen in simulated body fluid, CSH gradually transformed to hydroxyapatite. [source]


    Effects of Saccharide Set Retarders on the Hydration of Ordinary Portland Cement and Pure Tricalcium Silicate

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010
    Linghong Zhang
    The effects of aliphatic sugar alcohols (e.g., threitol, xylitol, sorbitol) on the hydration of tricalcium silicate (C3S) and ordinary portland cement (OPC) were investigated and compared with those of sucrose, a well-established cement set retarder. Only sugar alcohols which contain threo diol functionality retarded the setting of C3S and OPC, their efficacy increasing with the number of threo hydroxy pairs and, to a smaller extent, with the overall population of hydroxy groups. None, however, were as effective as sucrose. The initial and final setting times increased exponentially with the concentration of saccharide, although the hydration of OPC was less inhibited than that of C3S. Saccharides function as "delayed accelerators," that is, cement hydration is first inhibited and then proceeds faster than in saccharide-free cement. This behavior is consistent with the theory that the induction period is controlled by slow formation and/or poisoning of the stable calcium silicate hydrate (CSH) nuclei. The early inhibiting influence of saccharides on CSH precipitation is apparently stronger than on the growth of crystalline calcium hydroxide. Saccharides did not negatively affect the degree of hydration and compressive strength of fully set OPC paste; on the contrary, sorbitol yielded modest increases. [source]


    Natural Abundance 43Ca NMR Spectroscopy of Tobermorite and Jennite: Model Compounds for C,S,H

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2009
    Geoffrey M. Bowers
    There are few effective methods for characterizing the molecular scale structural environments of Ca2+ in hydrated cements, which has limited our ability to understand the structure of, for example, Ca,silicate hydrate (C,S,H). 43Ca nuclear magnetic resonance (NMR) spectroscopy has long been considered too insensitive to provide useful data in this regard, but 43Ca magic angle spinning (MAS) NMR spectra reported here for synthetic tobermorite and jennite with naturally abundant levels of 43Ca demonstrate that this is a viable approach. We show that spectra with useful signal/noise ratios can be obtained in a reasonable acquisition period (,2 days) using an H0 field strength of 21.1 T, 5 mm rotors spinning at a frequency of 5 kHz, and a double frequency sweep preparatory pulse sequence. Tobermorite and jennite produce relatively broad resonances due to their complex structures and structural disorder, however, the chemical shift differences between six-coordinate 43Ca in jennite and seven-coordinate 43Ca in 11 Å tobermorite are large enough that the signals are entirely resolved at this field. These data suggest that signal from ideal tobermorite-like and jennite-like sites in cement C,S,H can most likely be distinguished by 43Ca NMR and that this method will be a powerful approach for studying cement-based ceramic materials in the coming decade. [source]


    A Molecular Dynamic Study of Cementitious Calcium Silicate Hydrate (C,S,H) Gels

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007
    Jorge S. Dolado
    In this article, we study the polymerization of silicic acids (Si(OH)4) in the presence of calcium ions by molecular dynamics simulations. We focus on the formation and structure of cementitious calcium silicate hydrate (C,S,H) gels. Our simulations confirm that, in accordance with experiments, a larger content of calcium ions slows down the polymerization of the cementitious silicate chains and prevents them from forming rings and three-dimensional structures. Furthermore, by an analysis of the connectivity of our simulated silicate chains and by a count of the number of Ca,OH and Si,OH bonds formed, the relationship with commonly used structural models of C,S,H gels, such as 1.4 nm tobermorite and jennite, is discussed. [source]


    Influence of Activation Temperature on Reaction Kinetics in Recycled Clay Waste,Calcium Hydroxide Systems

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008
    Moisés Frías
    Obtaining pozzolanic materials from recycling of industrial waste and byproducts is a priority action of environmental policy all over the world. This paper describes the effect of activation conditions on the reaction kinetics in calcined clay waste (CCW)/calcium hydroxide systems. The CCW used in this work shows excellent qualities for use as supplementary cementing material in the manufacture of commercial blended cements. This research work presents an exhaustive study about the kinetics of a pozzolanic reaction in this cementing system. The results obtained by different techniques (DTA/TG, X-ray diffraction, and SEM/EDAX) confirm that the activation conditions (in the range 700°,800°C and 2,5 h of retention) have a direct effect on the formation and evolution of hydrated phases. Low activation temperatures favor the CSH gels' formation, while at higher temperatures aluminates (C4AH13) and aluminum silicate hydrates (C4ASH8, hydrotalcites) are predominant. [source]