TABLE OF CONTENTS When we speak of organic material, we generally forget the role of discreet molecules which have proved to be indispensable in modern construction technology and which intervene through their physico-chemical properties or their mechanical properties. These refer to essentially concrete admixtures air entraining agents, rheological admixtures (superplasticizers and derivatives) retarders, etc. and organics fibers used in certain concrete or hydraulic mortar formulations. We also refer to these materials as built-in ( in cement matrices). But more important are the admixtures.
Concrete is the base material for modern construction in developed societies. Everybody knows this but who can say what the concept of concrete holds? It is not enough to take a heap of stones and to sprinkle it with cement grout to obtain concrete. We will have to introduce the notion of the compactness of the aggregate structure and concretely consider the manner of obtaining a good packing. The processing associated to the physical, chemical and mechanical evolution of the initial mixture are an integral part of the definition of concrete.
We should also not forget that this generic term can also be applied to certain types of mixes, bituminous concretes as well as cement specific material. The problem does not exactly unfold in the same manner since both type of binders react differently from one another, but the starting point remains the same: a good concrete is the result of good packing of the granular constituents.
To obtain this effect, the...
