There is a potential in using magnesium oxide as a sulfate soils stabilizer. Magnesium oxide demonstrated a better ability as pozzolanic activator to GGBS than lime. The long-term swelling test was a good estimator of the development of expansive minerals. XRD results agree with the indirect estimation of the presence of expansive minerals. All the lime and none of the PC-8 treated soils, showed expansive behavior.