Application of electro-injection method in improving cement mortar durability

An electrochemical method for improving the durability of cement mortar by injection of nanoparticles (alumina (Al₂O₃)-coated silica (SiO₂)) is presented. In this method, nanoparticles are injected into cement mortar pores under an external electrical field, refining the pore structure of cement mortar. The efficiency of electro-injection nanoparticle treatment with different applied electric fields was evaluated by monitoring the evolution of cement mortar resistivity. The improvement of cement mortar durability after electro-injection of nanoparticles was assessed by examining the resistance to water absorption, carbonation, sulfate attack and chloride diffusion. The microstructure of cement mortar after the electro-injection treatment was analysed using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) and differential thermo-gravimetric analysis (DTG). The results show that cement mortar durability can be improved by the injection of nanoparticles under external electric field. The efficiency of electro-injection nanoparticle treatment increased with the increase of applied electric field. The resistance to water absorption, carbonation, sulfate attack and chloride diffusion were significantly improved by using the electro-injection method. The improvement in cement mortar durability can be attributed to the filling effect of nanoparticles.