HYDRATION RATE AND STRENGTH DEVELOPMENT OF LOW HEAT PORTLAND CEMENT WITH LARCE AMOUNT OF POZZOLAN

摘要

Following features have been found byrecent investigation held about old concrete structures(e.g. in Otaru Bay) , which is respected to estimatelong-term durability of concrete.;The cement used for old concrete construction,contained a large amount of Belite, mixed withPozzolan and its specific surface area was small.Then it is indicated that slow hydration of cement and mixingof Pozzolan make concrete durable through themicrostructure of concrete become dense.In this study, referring to above investigation,blended cement using low-heat Portland cement andsome of Pozzolan (fly-ash and coal-gasification slag)have been examined, with varying the mixing ratio ofPozzolan and these specific surface area.The conclusions are as follows.;(1)Hydration rate of low-heat cement and Pozzolan vary withthe blending ratio of Pozzolan.(2)To establish long-term durability, new type of blendedcement was considered, which hydrate slowly andcontinuously. A proper blending ratio of Pozzolan is to be50percent, and specific surface area of low-heat cement issmaller than usual and that of Pozzolan.(3)New design concept of concrete structure system, usingabove new type cement, was proposed.