Durability of High Performance Concrete in Relation to ‘External’ Chemical Attack
This chapter aims to analyse the behaviour of high performance concrete (HPC). One of the possible ways of investigating HPC behaviour in relation to chemical attack is to extrapolate from data available on 30 MPa concrete. HPC should also be more resistant to chloride ion attack, which is also linked to permeability, than ordinary concrete. The durability of HPC in relation to external chemical attack will thus be conditioned by the size of the existing crack network. The absorption by condensed silica fume (CSF) of lime, which is the most soluble hydrated constituent of cement, is certainly a guarantee of high durability. At pH 12.8, the protective film covering the reinforcement is dissolved, leaving the steel surface unprotected. When the cement paste in contact with the reinforcement becomes carbonated, corrosion begins. The action of aggressive agents will be investigated at the surface of a concrete structural element, and afterwards in relation to possible effects on the reinforcement.