Physical and Mechanical Behaviour of Porous Calcareous Mortars and Concretes

This paper presents a study of the evolution of physical and mechanical properties of mortars and concretes realised with calcareous aggregates. References mortar and concrete are prepared with siliceous aggregates. Measurements, realised on the 7^th, 28^th, 90^th and 365^th day, include determination of physical properties (porosity, geometry of the porous network - size and distribution of the pores family - N2 permeability, P waves velocities) and mechanical properties (uni- and triaxial compressive strengths, tensile and flexural strengths). Elastic parameters of the different mortars and concretes are calculated from the stress-strain curves. The properties of calcareous mortars and concretes evolve quickly during the first days. The total porosity and the permeability drop, whereas the compressive strength increases as soon as the setting begins. Calcareous mortars and concretes present higher tensile and flexural strengths than the references. Both tensile and flexural strengths increase faster than the compressive strength. S.E.M. observations show an early development of portlandite in contact with the calcareous aggregates and of ettringite around the siliceous aggregates. The evolution of the characteristics of calcareous mortars and concretes points out the importance of portlandite and hydrates in the initial phenomena and leads to obtain informations on the relationship between structure and properties of mortars and concretes as a function of aggregates type.