Long-term Study on Properties of High-strength Mass Concrete in PCCV(Prestressed Concrete Containment Vessel) (Monitoring Test Results and Durability of Concrete over 22 years)

摘要

This paper describes the strength gain properties of mass concrete specimens cast in wintertime and summertime. Subsequently we discussed the verification data for the effect of increasing durability of coating for protective finish and durability assessment for the coating itself.At first, the long-term properties of concrete is summerized. The compressive strength increases gradually from one year to 20 years. The strength of core sample is almost same as that of standard curing specimen at the 22~(nd) year. It was confirmed that the compressive strength is sufficiently larger than the specified design strength.Secondly, the effect of protective finish of coating is described. The protective finish of coating is expected to have chloride resistivity and restraint effect of neutralization. The performance and those effects are maintained judging from the results of follow-up surveys over 20 years The chloride resistivity of coated film is confirmed since the specimens with coating does not increase the chloride content even if at near the surface.Finally, the durability performance of coated film over 20 years is summerized. All of the specimens do not show marked deterioration such as blistering, stripping and cracking, do not show dirt and maintain favorable conditions over 20 years.It is concluded that the durability of mass concrete and finishing material is verified through monitoring tests described here over the long term. These tests are quite useful in case direct destructive tests for important buildings such as nuclear reactor buildings are restricted since the tests could be conducted under the same circumstances as actual buildings. This clearly demonstrates that the monitoring tests will make a substantial contribution to verify the integrity of the building and make the maintenace plan for the buildings.