STUDIES ON MECHANISM AND PHYSICOCHEMICAL PARAMETERS AT THE ORIGIN OF THE CEMENT SETTING .1. THE FUNDAMENTAL PROCESSES INVOLVED DURING THE CEMENT SETTING

The mechanical evolution and the structure of the cement paste have be en analysed in relation with the chemical evolution of the system. The setting process can be described as following two fundamental steps : the coagulation of cement grains during the first minutes following t he mixing and the rigidification of the coagulated structure which ari ses simultaneously with the acceleration of the hydrates formation. Du ring the coagulation step; the structure formed:is proved to be mechan ically reversible. The rigidification of the coagulated structure is p rovided by the hydrates formation in the Contact zone. The increase of the paste cohesion at this stage is proportional to the quantity of p recipitated hydrates, the structure thus rigidified becoming mechanica lly irreversible.