This research, that has been granted during several years by the Federal, aims to develop degradation models due to corrosion and chemical attack of mortar and concrete.
This federal research topic aims to develop degradation models due to corrosion and chemical attack of mortar and concrete.
The actual phase is the continuation of the study considering the diffusion of chlorides, the carbonation and the acids attacks. In this part of the research, we study the resistance of mortar and concrete to sulphate attack. The goal is to contribute to impositions related to the durability and to make evolve the standards NBN EN 206-1 et NBN B15-001.
Indeed, these standards or national prescriptions of most European countries are satisfied with prescribing concrete based on composition limits (maximal W/C, cement content, minimal resistance class and the utilisation of an air former) depending of their exposition to aggressions. Milieu classes XA and environmental classes EA prescribe to use a cement with a high sulphate resistance (HSR cement according to NBN B12-108) if the sulphate content is higher than 500 mg/l water or 3.000 mg/kg for a soil.
A study of 1989, concerning the reasons of bridges degradation, has shown that sulphate attack is the second cause of structure degradation after corrosion of the reinforcement.
During the first two years of this prestandardization research, the sulphate attack associated with secondary ettringite has been studied. In the second two years, we have studied the degradation due to the thaumasite formation that develops at low temperature. The Research is continuing at this moment on own resources.