Improvement of mortar durability by electrochemical technique

Abstract

An electrochemical technique was applied to improve mortar durability. Silicate ions were injected into mortar pores to react with calcium hydroxide by applying an electric field, resulting in densification of the mortar. The calcium ions in the pores of the mortar were electro-transported to the sodium silicate solution, which led to the formation of a surface coating. The durability of mortars after electrochemical treatment was evaluated by examining water absorption, carbonation depth, sulfate resistance and chloride diffusion. In addition, microscopic observations were made using scanning electron microscopy, mercury intrusion porosimetry, thermogravimetric analysis and differential scanning calorimetry. The results indicated that the resistances to water absorption, carbonation, sulfate and chloride diffusion were improved by use of the electrochemical technique. The improvement in mortar durability was attributed to the combined actions of densification and the coating layer produced on the mortar surface during the electrochemical treatment. However, the coating layer, being thin and of high porosity, played only a minor role.