Effects of silicate modulus and alkali dosage on the performance of one-part electric furnace nickel slag-based geopolymer repair materials

Traditional ordinary Portland cement (OPC) repair materials with high carbon emissions and low bond strength, urgently need to be improved. A one-part electric furnace nickel slag-based geopolymer (OENG) repair material was prepared through mechanical activation. Also, the effects of silicate modulus and alkali dosage on the properties of compressive strength, bond strength, and drying shrinkage were investigated, then analysed using XRD, DTG, MIP, and SEM microscopic tests. Results indicate that the compressive strength, flexural strength, and bond strength of OENG repair mortars first rise and then fall as the silicate modulus and alkali dosage increase. In contrast, the trend of drying shrinkage is the opposite. The specimen with a silicate modulus of 1.2 and an alkali dosage of 6.0 exhibits the best performance. The hydration product has a dense pore structure and maximum adhesion of 7.3 MPa, which is superior to the OPC mortar matrix and meets the performance requirements of repair materials. This study provides a theoretical basis for the application of one-part electric furnace nickel slag-based geopolymer in building repair.