An accelerated sulfate resistance test for concrete

The sulfate resistance of concrete was tested using drying-immersion cycles of varying duration in different sulfate solutions. The measured expansion in the different protocols showed a correlation to the sulfate profiles in the test specimens determined by EDX. Based on the magnitude of expansion and the test duration, a suitable protocol for testing job-site concrete was identified. A matrix of 20 concrete mixtures was tested with this protocol. The test permitted to distinguish the effect of cement type, w/c and paste volume on expansion. Measurements of the dynamic E-modulus made it possible to link expansion and mechanical damage and to define a limit value for expansion. As this test appears to be suitable to determine the potential of concrete for expansion induced by ettringite formation due to sulfate ingress, it was introduced into the Swiss norms.