Abstract

It is very important to improve and secure durability of reinforced concrete (RC) building and housing, in order to extend the service life of it. In this study, these were studied experimentally that the contribution ratio of blended cement to the carbonation resistance of concrete when a part of OPC replaced to FA or BFS much more were used for concrete, and the effect of carbonation suppression required for an effective finishing materials when these were applied for concrete surface. As a result, we were able to obtain the knowledge that the contribution ratio to the carbonation resistance of concrete using blended cement with different mixture replacement ratio, and the effect of carbonation suppression required for 4 types of finishing materials and its specifications, from the viewpoint of securing durability and extending the service life of RC structures. Therefore, these were considered to be able to sufficiently contribute to the review of the evaluation method or technical standards concerning about the durability of RC structures prescribed in "Housing Quality Assurance Act" in Japan.

Abstract

A model building made out of concrete block specimens whose surfaces were coated with various finishing materials was constructed for the outdoor exposure test. After 30 years of outdoor exposure, the deterioration of finishes and their carbonation and corrosion inhibition effects were investigated. As a result, the following conclusions were obtained: Though the deterioration levels differed depending on their types and thickness, all finishing materials showed some kind of deterioration after 30 years‘ long-term outdoor exposure. The progress of carbonation and corrosion are prevented when the surface is coated with finishing materials of sufficient thickness or waterproof effect. Regarding the relationship between corrosion depth and carbonation depth, corrosion is initiated after the carbonation front reaches the area. It usually takes a while to initiate corrosion in the carbonated area, not immediately after the carbonation reaction. When the concrete surface is properly coated with finishing material, corrosion may not be initiated in non-carbonated area in concrete where the pH level is not lowered.

Abstract

In this paper, we discussed the concept for appropriate repair period for finishing materials of reinforced concrete structures. We investigated the actual building repair cycle, the progress of carbonation of concrete, and the adhesion strength of various finishing coating. In addition, we carried out 10-years exposure test of concrete with various finishing to evaluate the progress of carbonation and the degree of deterioration of the finish coating material. From these results, we showed the possibility of extending beyond the current repair cycle.