The length change is negligible and can be attributed to the normal distension of concrete. On the other hand, concrete suffering from mass loss gives a good indicator about the durability of SCC. Permeability of concrete is an important factor in classifying its durability generally; concrete with low Permeability will afford better protection of the reinforcement within it than concrete with high Permeability. In this paper, the assessment of magnesium sulphate (MS) attack on concrete containing various ratios of the supplementary cementitious materials (SCM) was investigated for concrete containing FA, RHA, and GGBS with cement replacement levels of 15%, 10%, and 5%, respectively, based on the selected samples from the concrete to the statement of the effect of magnesium on some of the characteristics of concrete such as compressive strength, height, and weight compared with similar samples but under laboratory conditions dry and moist water treatment. Test results showed that the SCC content SCM appear to have higher strength values than those stored in water and air sample; the highest value of mass loss is recorded for the control mixture compared with concrete content SCM, and the change in length in curing concrete is much less relative to the change for concrete immersed in MS.