6533b7d7fe1ef96bd126806e

RESEARCH PRODUCT

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

subject

description

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 studied on the hydration of the mineral compound responsible of the final properties of OPC, tricalcium silicate, were related to the characteristics of the organic admixtures. The interactions of these organic compounds such as their adsorption on calcium silicate hydrate (C-S-H) and their complexation with calcium, hydroxide and/or silicate ions in solution were identified in systems at equilibrium and correlated to the retarding effect generated by the organic molecules on the hydration of tricalcium silicate.The impact of hexitols which differ from one another in the stereochemistry of their hydroxyl groups on the dissolution-precipitation process of the hydration of tricalcium silicate was studied. The influence of these polyols on the hydration of a calcium aluminate and calcium sulfate mixture was explained by their adsorption on ettringite and AFm as well as by their ionic complexation in solution. Finally, this study focused on the consequences of the interactions of hexitols with ettringite and aluminate ions in solution on the hydration of the silicate phases present in OPC.