Abstract
Concrete mixes of water-cementitious ratio (w/c’s) = 0.45, 0.5, 0.65 were used to prepare 100 mm cubes and 75 x 75 x 285 mm prisms. Moderately high alumina slag was incorporated in proportions of 50 or 70% and the specimens immersed in sodium sulphate or magnesium sulphate solutions of 50 g/L as SO4. Emphasis in the study was to assess sulphate resistance using concrete samples and other non-conventional methods. Expansion measurements, mass loss and corrosion attack or physical deterioration of concrete were monitored for 69 weeks. It was found that the results of expansion, mass gain and corrosion were consistent for Na2SO4 solution, showing improved sulphate resistance with increase in ground granulated blast-furnace slag (GGBS) incorporation. The expansion observations under MgSO4, while showing increased resistance with use of GGBS, gave conflicting results between expansion on one hand and, mass gain and corrosion on the other with the most severe corrosion occurring in concrete containing the high 70% GGBS. The corrosion test method appears to give a more realistic indicator of physical damage under MgSO4 attack compared to expansion measurement.