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Calcium Silicate Hydrate (calcium + silicate_hydrate)
Selected AbstractsHierachically Nanostructured Mesoporous Spheres of Calcium Silicate Hydrate: Surfactant-Free Sonochemical Synthesis and Drug-Delivery System with Ultrahigh Drug-Loading CapacityADVANCED MATERIALS, Issue 6 2010Jin 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) GelsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007Jorge 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 CapacityADVANCED MATERIALS, Issue 6 2010Jin 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 SilicateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Linghong 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] A Molecular Dynamic Study of Cementitious Calcium Silicate Hydrate (C,S,H) GelsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2007Jorge 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] | ||||||||||