Calculation of Sulfate Diffusion Coefficients of Concrete Based on Migration Test

Abstract

External sulfate attack is a remarkable and complex phenomenon of degradation of cement matrixes. This paper proposes a method to calculate sulfate diffusion coefficients based on ion migration testing, in order to establish parameters for concrete service life prediction models based on a fast test. The influence of the type (sodium and magnesium) and concentration (5% and 10% SO42−) of the sulfate solution for a concrete matrix was evaluated in the tests. Sulfate concentrations were monitored by measuring the electrical conductivity of the anode compartment. The results were validated by comparing them with those obtained in natural diffusion tests. Similar sulfate profiles were obtained for concrete samples after 1 month of migration and after 3 and 6 months of diffusion, mainly for magnesium sulfate. The greatest correlations between the calculated diffusion coefficients were achieved at higher concentrations of SO42− in the cathode compartment. The results indicated that the proposed migration method enables the calculation of the sulfate diffusion coefficients in concrete.