Search results for "tricalcium silicate"
showing 10 items of 10 documents
The Structure, Stoichiometry and Properties of C-S-H Prepared by C3S Hydration Under Controlled Condition
1998
Hydrations of tricalcium silicate undertaken by keeping constant lime concentration in solution in an open system and in diluted suspensions for different values of [CaO] ranging between 6.5 and 30 mmol/1 show that the lime concentration in solution is the parameter which determines the main characteristics of the reaction and products. The stoichiometry of C3S hydration products vanes with lime concentration in the same way as synthetic C-S-H until C/S c.a. 1.5 corresponding to about [CaO] =20 mmol/1. Beyond this concentration, single phase C-S-H samples were obtained with 1.8<C/S<2. The discontinuity of the variation of stoichiometry with concentration is characteristic of an invariant po…
Observation directe de la croissance d'hydrosilicate de calcium sur des surfaces d'alité et de silice par microscopie à force atomique
1998
Direct observation of the growth of calcium silicate hydrates, the tricalcium silicate hydration products, at the solid-solution interface were performed by atomic force microscopy. The covering of the surface of alite or silica by a three-dimensional oriented aggregation of nano particles of calcium silicate hydrate is always observed whatever the sample. All observations and quantifications made on calcium silicate growth at the submicronic level are in agreement with the data deduced from the study of the system evolution at the macroscopic level.
Influence of temperature on the hydration products of low pH cements
2012
International audience; The chemical evolution of two hydrated "low pH" binders prepared from binary (60% Portland cement + 40% silica fume) or ternary (37.5% Portland cement +32.5% silica fume + 30% fly-ash) mixtures was characterized over one year at 20 degrees C. 50 degrees C, and 80 degrees C. The main hydrates were Al-substituted C-S-H. Raising the temperature from 20 to 80 degrees C caused a lengthening and cross-linking of their silicate chains. Ettringite that formed in pastes stored at 20 degrees C was destabilized. Only traces of calcium sulfate (gypsum and/or anhydrite) reprecipitated after one year in some materials cured at 50 degrees C and 80 degrees C. The sulfates released w…
Rate-limiting reaction of C 3 S hydration - A reply to the discussion “A new view on the kinetics of tricalcium silicate hydration” by E. Gartner
2018
Abstract In the case of coupled solids-solution reactions, any mean accelerating or decelerating one of the reaction, will also change the other reaction(s) in the same way, through the coupling mediated by the solution. The observation of any kinetic change by one of these means should not lead to too rapid conclusion on the limitation of kinetics and it must be done with great caution. Contrary to what Gartner mentioned, the acceleration of C3S hydration by the addition of calcium silicate hydrate seeds, is not a trivial evidence suggesting that hydration kinetics “has to be” limited by the C-S-H precipitation and that the C3S dissolution can be neglected. In our paper, efforts have been …
Hydration of cementitious materials, present and future
2011
This paper is a keynote presentation from the 13th International Congress on the Chemistry of Cement. It discusses the underlying principles of hydration and recent evidence for the mechanisms governing this process in both Portland cements and other cementitious materials. Given the overriding imperative to improve the sustainability of cementitious materials, routes to reducing CO2 emissions are discussed and the impact of supplementary materials on hydration considered. (C) 2011 Elsevier Ltd. All rights reserved.
Formation of the C−S−H Layer during Early Hydration of Tricalcium Silicate Grains with Different Sizes
2005
Portland cement is a mixture of solid phases which all react with water. Tricalcium silicate (Ca3SiO5) is its main component and is often used in model systems to study cement hydration. It is generally recognized that setting and hardening of cement are due to the formation, by a dissolution-precipitation process, of a calcium silicate hydrate (C-S-H) on anhydrous grains during Ca3SiO5 hydration. The purpose of this paper is to study the effect of Ca3SiO5 particle size on the nucleation-growth process of C-S-H. An experimental study of the rate of hydration by using different grain sizes under controlled conditions has been performed. The experimental data have been compared with results o…
Retrograde filling material in periapical surgery: a systematic review
2021
Background Periapical surgery focuses on the treatment of teeth with persistent periapical lesions when orthograde root canal treatment fails. Although MTA® is the gold standard material for retrograde filling, Biodentine® - a tricalcium silicate-based cement - has been proposed in order to resolve several of its limitations. A systematic review has been carried out to compare the physicochemical properties of Biodentine® versus MTA® as root-end filling material in periapical surgery. Material and Methods An electronic search was conducted by two independent examiners during March 2020 in the Cochrane, PubMed-MEDLINE and Scopus databases. In addition, a manual search was made in specialized…
Interactions between chemical evolution (hydration) and physical evolution (setting) in the case of tricalcium silicate
1994
This paper describes recent experimental results concerning investigation of the parameters which determine, on the one hand, the kinetics of hydration of tricalcium silicate and the thermodynamic, morphological and structural characteristics of C-S-H and, on the other hand, the evolution of the particle interactions at the origin of setting. It is shown that, in both cases, lime concentration in solution is the most important parameter. As a consequence, the chemical evolution of the system, which controls the lime concentration in solution, determines the nature of particle interactions and the physical evolution of the suspension or paste. In return, the contacts, between particles, resu…
Comparative Cytocompatibility and Mineralization Potential of Bio-C Sealer and TotalFill BC Sealer
2019
The aim of this study was to investigate the cytocompatibility and mineralization potential of two premixed hydraulic endodontic sealers compared with an epoxy resin-based root canal sealer. The cellular responses and mineralization capacity were studied in human periodontal ligament stem cells (hPDLSCs) that were exposed to premixed hydraulic sealers, Bio-C Sealer (Angelus, Londrí
Study of parameters endogeneous and exogeneous to ordinary Portland ciment influencing hydration of its main phase : tricalcium silicate
2012
This work devoted to study various parameters influencing hydration of silicate phase main Ordinary Portland Cement (OPC) was performed at the Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB). This study is part of the project "Crystal Growth Control" initiated by BASF in order to monitor and provide the best as possible the hydration of Ordinary Portland Cement. The dissolution of alite, like the pure C3S one, is fast in pure water. Speed decreases with deviation from equilibrium and the concentration of aluminates ions in solution. There is also an adsorption on the surface of the aluminum which is into the alite and released by dissolution. Germination and growth of C-S-H has bee…