Search results for "Hydratation"

Study of the action of phosphate ions contained in the mixing water of the hydration of a Portland cement.

2005

Cementation is considered as the most attractive solution for the conditioning of low and intermediate radioactive wastes. The species contained in these wastes can strongly influence the reactivity of the cement pastes, it is in particular the case of the ortho-phosphate ions which are found in the evaporation concentrates. The aim of our work was to determine the influence of these ions on the hydration and the rheological properties of the cement pastes at early age as well as the mechanical and physical properties on the hardened material.

Influence of the stereochemistry and of the functionality of organic molecules on the hydration of cementitious compounds

2015

The current limited knowledge on the interactions between organic admixtures and mineral phases as well as their influence on the hydration mechanisms of the Ordinary Portland Cement (OPC) represents a real limitation in the development of new organic products with improved and controlled properties. Here, this study intended to understand why and how organic admixtures modify the setting time of OPC by progressively varying the characteristics of simple organic molecules such as their charge, functional groups (hydroxyl, hydroxy-carboxylate, carboxylate, sulfonate and phosphonate) and the stereochemistry of their hydroxyl groups.The different retardations induced by the organic molecules s…

Involvement of the plasma membrane in saccharomyces cerevisiae resistance to hydric perturbations : key role of ergosterol

2011

Preservation of microorganisms of interest (ferments, probiotics) in dry form is widespread in the industry. However, the dehydration processes lead to variable survival rates according to the group, species and strain of microorganism considered, but also according to the type of process used (drying, freeze drying, freezing). The plasma membrane (PM), by its position between the intra-and extracellular environment, is a target of hydric perturbations. Changes in this structure during hydric stresses are described to be directly involved in microorganism death. Understanding of membrane responses occurring during a dehydration/rehydration cycle is essential to maximize the survival of micr…

Protection of yeast cells in micro-organized shells of natural polyelectrolytes during drying process

2016

The encapsulation techniques are applied in various fields and for various applications. The layer-by-layer self-assembly (LbL), one of the encapsulation techniques, is built by the electrostatic attraction between oppositely charged polyelectrolytes, and the topmost layer determines essentially the sur-face properties of the edifice. This technique offers several advantages (low cost, simplicity of process and equipment, biocompatibility and biodegra-dation, etc.). In this present paper, results of the protection of Saccharomyces cerevisiae yeast cells in microorganized shell of natural polyelectrolytes during dehydration process are reported. To apply the LbL method to individually encaps…

Prévenir la déshydratation tout en contribuant au lien social en EHPAD : impact du chariot GLACE

2023

Influence of aluminates phases hydration in presence of calcium sulfate on silicates phases hydration : consequences on cements optimum sulfate

2012

The mechanical properties of hydrated cements need to be optimized according to the nature of cement products. Among the factors of optimization, the addition of calcium sulphate intended to regulate the reactivity of tricalcium aluminate (C3A), in quantity and quality in cement is an essential parameter.The advancement of knowledge on the mechanisms of hydration of each cement phase allows a study devoted entirely to the concept of optimum of sulphate. We studied simple system that we complicated and we studied the evolution of hydration, porosity and mechanical properties of cement at different age. The first system studied was the mixture C3S/gypsum, the objective was to determine whethe…

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…