KEY FEATURES IN VIEW OF MODELLING THE PERMEABILITY OF CONCRETE

When it comes to the reliability of durability predictions for concrete structures, knowledge among the permeability has turned out to be a prerequisite. The permeability of concrete is a material property that hides several different ‘features’ which potentially contribute to this material property. In this paper, the contributions of the different “sources” in a concrete are the cement paste, Interfacial Transition Zone (ITZ) and microcracks. Their individual contribution to the magnitude of permeability is a subject that is worthwhile to be examined in detail. It provides the necessary knowledge on the magnitude of the internal structure's transport properties. The permeability, in this respect, is a property which is a measure for the material's resistance against the ingress of aggressive substances, and with this, a measure for the material's long term durability performance. In this contribution to the congress, laboratory and field permeability tests on 28 days and 36 years aged specimen are presented. The results are evaluated with respect to the internal sources, i.e. paste, ITZ and cracks that contribute to permeability. SEM studies will be presented that clarifies the differences of the specimen's micro-structure. The results show the relationship between moisture movements on the one hand and the changes in the micro-structure on the other.

• INTRODUCTION

• PERMEABILITY OF CONCRETE

• TESTING PROGRAMME

• EVALUATION OF RESULTS

• DISCUSSION AND CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES