Microstructure and properties of hybrid coal gangue-based alkali-activated cement

Addition of Portland cement in low-calcium aluminosilicate-based alkali-activated materials can provide rapid hardening at room temperature, thus modifying microstructure and mechanical properties. In the present study, the effect of Portland cement addition on alkali-activated materials, cured at room temperature, was analysed by mechanical strength test, FT-IR and electrochemical impedance spectroscopy. The results showed samples hardening at room temperature after 24 hours and compressive strength of 26 MPa (7 days) for 5% of OPC addition. Hybrid alkali-activated cements presented higher sorptivity and lower electrical resistance than alkali-activated cement without OPC addition which can be related to more connected pores. The analysis of EIS spectrum highlights continued formation of microstructure over the ages of alkali-activated cement and can be related to mechanical properties and sorptivity.