Setting and hardening of cement based materials: Which differences between mortars and concretes?

Abstract

In this paper, the setting and hardening periods for concrete are studied by means of "equivalent" mortar. Two categories of mortars can be envisaged: one has the same thermal properties as the one of the relative concrete, another one presents the same specific area of the aggregates. The experimental approach is based on the use of a P-wave propagation device at low frequency (200 Hz). The wave velocity and two pressure ratios, which are linked to the wave damping and Poisson effect, are monitored during time. The evolutions of rheological moduli during setting are then obtained by inverse analysis, by means of a viscoelastic behaviour law obtained from a periodic homogenisation modeling. These mechanical quantities proved that only very restricted relations can be obtained from concrete to mortar equivalences.