Mechanical strength development of three types of mortars(sea water mixing alkali activated slag mortar(SAAS), tap water mixing alkali activated slag mortar(TAAS) and cement slag blended mortar(CS)) after wetting drying cycles in artificial sea waters was investigated. The corrosion behaviors of two types of rebars, low carbon rebar(LC) and low alloy rebar(LA), in three types of mortars were tested via corrosion potential(Ecorr), linear polarization resistance(RP), and electrochemical impedance spectroscopy EIS measurements. The results show that, during the wetting drying cycles, SAAS and TAAS mortars have higher compressive strength than CS mortars. No significant difference of corrosion behavior can be observed for rebars in SAAS mortars and TAAS mortars. After 6 months of wetting drying cycles, it is indicated by increasing Rp and charge transfer resistance (Rct) values that both LC and LA in all mortars exhibit low corrosion rate.