CHLORIDE CONTENT pH VALUE IN THE PORE SOLUTION OF CONCRETE DURING CARBONIZATION: ANALYSIS OF EXPERIMENTAL STUDIES

Abstract

The chloride content and the pH value of the pore solution in the steel reinforcement zone are the determining parameters of the initiation and rate of corrosion. The pore liquid of the cement stone was isolated from the pore space by high pressure during the study. The effect of the water-cement ratio, age, and the addition of chloride to the fresh mixture on the chloride content in the pore solution was evaluated by ion chromatography. At the same time, the pH value of the pore solution is determined. The dissolved chloride content decreases with an increase in the water-cement ratio. The amount of bound chloride increases over time, but decreases with a decrease in the content of dissolved chloride in the pore solution. A significant effect of carbonation on the content of dissolved chloride in the pore liquid was noted. With complete carbonation, the content of dissolved chloride in cement stone increases by 2-12 times. The bound chloride decreases by 27%-54%, the pH value decreases from 13.2 to 8.0 due to carbonation. It can be concluded that carbonation not only reduces the pH value, but also releases bound chloride. This is one of the obvious reasons why the combined effect of chloride penetration and carbonation accelerates the corrosion of steel and shortens the service life of reinforced concrete structures.