A probabilistic approach to the long term durability of concrete structures.
Jean-Michel Torrenti (IRSN/DESTQ/DICST & ENS Cachan)
Forum EUROSAFE, Berlin, 8-9 novembre 2004
Concrete is a heterogeneous material. A probabilistic approach appears to be more appropriate than a deterministic approach when concrete is required to have a very long lifetime, which is the case for the storage of nuclear waste.
We will start by analysing variations of concrete properties on a site through the distribution of mechanical strength. This distribution is represented approximately by a normal law for characteristics known in EC2. Experimental results respect this law.
The very long term deterioration of concrete (calcium leaching) is modelled in a simplified manner by prediction of the degraded depth after 300 years. The deterministic approach can be compared with the probabilistic approach, and it is found 1) that the average value of the distribution of degraded depths is similar to the deterministic value and 2) that it would be relevant to introduce a characteristic value (95% fractile) to take account of the width of the distribution.