Development of conformity criteria for durability and its influence on service life predictions

Abstract

To ensure the quality of produced concrete batches, it is often verified whether a specified concrete compressive strength is reached by the application of conformity control. The conformity criteria used for this purpose are related to the probability of accepting a batch, in relation to a specified quality. Batches fulfilling the conformity criteria are accepted, whereas others are rejected. In this way, the outgoing quality of the accepted concrete is higher than without the application of conformity control. This is the result of the filtering effect of conformity control and affects the probability of failure of concrete structures. Instead of only applying conformity control to the concrete compressive strength, a similar procedure could be applied to durability related variables. One example hereof is the diffusion coefficient of the concrete. When conformity criteria are defined and applied in relation to the diffusion coefficient, the result will be a filtering effect on the distribution of the diffusion coefficient. The outgoing distribution will have a lower mean value and standard deviation compared to the incoming distribution. This will influence the time-dependent reliability of reinforced concrete structures. This paper investigates the effect of conformity criteria for diffusion coefficients on the service life and failure probabilities of reinforced concrete elements. The filtering effect is investigated by a numerical study applying analytical methods and numerical integration.