Abstract
A previous study argued that application of a low-gas-transmittance coating film on a carbonated concrete can recovered its carbonation front because the coating covering resulted in further hydration and hydroxide-ion movement toward the coating-adhesion boundary. This argument arises a hypothesis; the above mentioned hydration and ion movement can occurs when a carbonated concrete covered with a film is placed in a dry condition. This study therefore measured pH, moisture content and carbonation depth of samples which were carbonated concrete with a paint film in some dry conditions. Our finding is that applying a low-gas-transmittance coating film kept relatively high moisture content inside, and slightly increased pH of carbonated area. Our hypothesis related to the ion movement was thus validated. Nevertheless, only applying a film was not enough to recover carbonation, but applying saturated potassium hydroxide solution before painting showed a tendency of a tiny recovery of the carbonation.Further work need to achieve a satisfactory recovery of the carbonation.
