Carbonation in concrete structures has been handled as the most fundamental and critical factor related to the durability of reinforced concrete. As a result, there have been efforts to develop repair materials to control carbonation As one of these efforts, alkali recovery agents have been presented as materials for increasing the re-alkalization and durability of carbonated concrete structures. However, in applying them in the field, the performance and quality of concrete recovered after an alkali recovery agent is applied has not been fully assessed. Therefore, to examine the recovered performance of concrete structures resulting from the application of an alkali recovery agent, the present study assessed the depth of carbonation and the degree of deterioration of 20 years or older reinforced concrete structures, and analyzed the quality of concrete after applying an alkali recovery agent to the structures. This study aimed at providing basic information for the application of alkali recovery agents in the field. In this experiment, alkali recovery agents of the lithium silicate line, which are most common in Korea, were applied and cured using concrete of the same size. The degree of recovery was investigated according to the length of time in the initial curing stage, and based on the investigation, the maintenance performance of the alkali recovery agent was assessed according to the age of exposure to the open air. For these tasks, this experiment sampled concrete of different degrees of deterioration, applied alkali recovery agents to them, and observed re-alkalization and changes in the internal texture of the concrete.

In previous research team had reported that the durability of carbonation is improved by filling voids due to the saponification reaction of oil and concrete. The purpose of this study was to have experimental investigation the effect of mock-up experiment on the carbonation resistance of the waste concrete admixture.

This study proposed a technique to detect the carbonated concrete region in the image of concrete sprayed with phenolphthalein liquid. Test results showed that the carbonation region can be detected accurately using the proposed technique.

In previous research team had reported that the durability of carbonation is improved by filling voids due to the saponification reaction of oil and concrete. The purpose of this study was to have experimental investigation the effect of mock-up experiment on the carbonation resistance of the waste concrete admixture.

Concrete with a pore solution of pH 10-12 is less alkaline than sound concrete but would still produce a strong color hange with phenolphthalein indicator. It therefore follows that the indicator test is likely to underestimate the depth to which carbonation has occurred. The indicator has not changed color near the top and bottom surfaces, suggesting that these near-surface regions are carbonated to a depth of at least 3 mm from the top surface and 5 mm from the lower surface. Where the indicator has turned purple - the center of the slab - the pH of the concrete pore fluid remains high (above 8.6, probably nearer 10).. Based on the above technical background, this study was devoted to examine the depth analysis of carbonated concrete quantitatively.

The purpose of this study is to estimate and quantify the effect of carbonation of concrete on a surface electrical resistivity measurement. Samples of three mixes with difference W/C ratios were prepared and exposed in a carbonation chamber for up to 330 days. The results show that carbonation leads high electrical resistivity. The increase is substantial and has been shown to proportional to the extent of the carbonation by some of extent. The relationship between electrical resistivity and carbonation depth is taken in the study. Resistivity ratio of carbonated concrete to air concrete decreased significantly from the specific carbonation depth, however, Resistivity ratio of carbonated concrete to air concrete had a linear relation with carbonation depth.