Service life of white concretes exposed to chlorides: the influence of the cement and the diffusion coefficient

Abstract

The corrosion of reinforcement due the action of chloride ions (Cl-) is one of the most common damages in reinforced concrete structures, decreasing the durability of those structures. The durability may be numerically expressed by the service life and the solutions from the second Fick`s Law are normally used to obtain service life values. This paper presents the results of a study on the applicability of the error function solution using two cement types: CP B and CP IV. Concretes were produced with three w/c ratios (0,4; 0,5; 0,6), and submitted to compressive strength and the chloride ingress tests over a period of 6 months. The results showed that the compressive strength and the diffusion coefficient (D) were higher for CP B than for CP IV. The value of D decreased along the test period for both types of cement, resulting in an increase of the estimated concrete service life. As the error function solution does not consider the variation of the parameter D, it does not adequately represent the transformations that happen in concrete structures over time, and the estimated service life does not correspond to the real one.