An experimental study on the roles of water saturation degree and aggregate size in the mechanical response of cement-based composites

Desiccation of concrete induces the formation of microcracks leading to mechanical damage of concrete structures. Damage concentrates in the interfacial contact zone (ICZ), like also between aggregate particles. This damage, induced by drying, can be characterized in function of the ‘Saturation level degree’ variations. The main purpose of this study is concerned with specification of mechanical reactions and basic material constants for studied cement based composites during the desiccation process. In order to reduce number of analyzed factors, it was decided to use as aggregate particles glass and polystyrene spheres. This type of aggregate allows the characterization of almost exact ICZ. Each series of composite is a mixture of cement paste and 35% of spheres. In this first approach, only one diameter of aggregate particles is placed in one series of composite. Mechanical tests performed were compression tests: uniaxial, hydrostatic and quasi-triaxial, as well as non-direct tension tests.