Proceedings pro013 : 2nd International RILEM Symposium on Hydration and Setting

Comparatively to the considerable number of works devoted to hydration and to the microstructure development in cement paste, those dealing with the fundamental mechanisms of setting are very few. Nevertheless, setting that marks, at the macroscopic state, the passage from the soft state to the hard state of the paste has a capital importance on the practical point of view and users are increasingly aware that final properties of the concrete is depending on characteristics of the paste at early age. The growing interest of the engineers for rheological measurements are a proof. On the other hand, the improvement of concrete performances is practically limited currently to two parameters, the porosity and the quantity of hydrates formed at a time t. To find new means of action necessitates to know processes at the origin of the paste cohesion from mixing to setting and hardening.
From a more microscopic point of view, setting concerns the early formation of a three dimensional network and its initial development of strength. It occurs during early hydration stage of cement paste or other mineral binders while the paste is still a dense suspension of particles in which different processes are involved such as electrokinetic processes, percolation, nucleation and growth of new phases...The understanding of the exact relation between the pure chemical evolution, hydration, and the cohesion emergence requires the mastery of concepts from different fields of science and so an interdisciplinary approach. It is the reason why, under the impetus of ATILH (French Technical Association of Industries of Hydraulic Binders) and Jacques Baron especially, the first workshop was organised in 1991 to promote the discussion between experts of cement chemistry and experts of colloid science.
These discussions with colloid scientists about particle interactions occurring during the early age were very fruitful. Following the successful first workshop, several French teams of physicists and physico-chemists have begun to be interested in the fundamental problems related to setting. On the other hand, more and more researchers and engineers worldwide are concerned with the evolution of the properties of cement or other mineral binders during the workability period. As a consequence, this second edition focused more on setting problem.

Three essential points have been covered balancing the theoretical approach and the practical aspects:
- the fundamental principles allowing to understand the origin of setting and identify the
relevant parameters,
- methodologies and experimental techniques leading to a better description of the system,
- the influence of relevant parameters on the evolution of systems of practical interest.

The Proceedings are arranged in four parts:
- interparticular interactions : from swelling to setting,
- fundamental mechanisms of adhesion. Relevance to particle interactions, sticking and
aggregation in a fluid medium,
- crystallisation concepts in aqueous solutions : influence of solubility and composition of
solution on nucleation and growth,
- rheology of pastes: systemic rheology : a new tool for the study of hydration and setting of
cement pastes.

Contents

Part 1: Particle interactions at the origin of setting

Part 2: Nucleation, growth and properties of the crystallisation contact phase

Part 3: Rheology of cement pastes, properties and tools

Part 4: Setting and properties of hardening mineral binders