ABSTRACT
In general, concrete has high alkaline environment and pH is more than 12. However, the internal pH of concrete reduces due to the penetration of degradation factors such as carbon dioxide and sulfate ion. If the progress reaches near the rebar, nonconductive coating deteriorates, due to decrease in pH below a certain level causing corrosion of rebar and decreasing durability of concrete structure. Therefore, it is known that the internal pH is very important factor to determine the durability of concrete, but there are few studies about the measuring techniques of estimating the internal pH of concrete. In this study, a new method for estimating the internal pH of concrete is proposed. Internal pH is estimated by measuring the OH ions in the drilled powder extracted from degraded concrete. From experimental results, there is a possibility that the proposed method can be inspected easily and in detail comparing with the conventional test methods, such as the neutralization depth by phenolphthalein method.
