Predicting durability of high performance concrete
Durability of building materials is a very important issue that depends heavily on exposure to different climatic conditions. Investigation of the damage behaviour of individual materials provides a basis to assess the life-time of constructions such as roadways, bridges, tunnels and standard buildings. In particular, the manufacture of high performance concrete (HPC) involves a combination of ultra strength concrete with industrial by-products and admixtures, such as silica fume or fly ash. This extends the limits of the HPC as a structural material, which makes prediction of its life time a very difficult task. Motivated by this, the LIFECON project focused on systematic studies of the durability of different concrete design concepts, exposed to various climatic conditions in Europe. By correlating laboratory data against data coming from in-field tests, researchers were able to analyse deterioration mechanisms for development of degradation models. More specifically, test results were coupled with data derived from observations of in-service structures in order to assess the behaviour of the different HPC mixtures in the field. The latter were correlated with laboratory studies offering an assessment of the durability behaviour of HPC mixtures against different exposure classes. On the basis of the deviations in the behaviour of the various HPC mixtures exposed to different climatic conditions, models were designed and analysed to describe the degradation processes. The deterioration models comprised several damage mechanisms in relation to the HPC mixtures and the exposure classes of the concrete standard EN 206. Aided by these modelling tools, mixtures with an improved resistance against different climatic conditions can be evaluated. Such estimations can provide the basis for developing recommendations for HPC production with constituents falling within fixed limits and acceptance criteria according to EN 206 exposure classes. Apart from contributing to lifetime prediction of HPC as far as durability is concerned, guidelines were also generated. These guidelines refer to service life evaluation, classification to EN206 service class, and recommendations to industry for HPC applications. Potential partners for further use of the results include designers, material suppliers, and/or other research organisations in the construction sector.
