The durability of reinforced concrete

The poor performance of a large number of modern reinforced concrete structures with regard to durability is already a major problem. Within Australia the maintenance cost per annum for the repair of structures showing signs of durability distress is in excess of 100 million dollars. It is of concern that recently constructed structures seem to be less durable than older ones. Modern concrete technology has allowed the production of equivalent concrete strength with a much lower cement content and hence lower durability. It will be shown that increasing the cement content will not always be conducive to improved durability. The durability of concrete depends on the durability of each component of a concrete mix and the durability of the reinforced concrete matrix as affected by the interaction of the components in a particular environment. Adequate compaction and curing are vital for the concrete to realise its full potential with regard to durability. These two construction controlled parameters are of fundamental importance if achieved durability is to match the designers expectations. The lack of durability of modern reinforced concrete structures commands engineers to ensure that the level of concrete technology is matched by a level of understanding of the implications of that technology as regards the durability performance of reinforced concrete (a).