Composition, Structure Of Super High Strength & High Performance Concrete And How To Compensate For Its Shrinkage

Super high strength & high performance concrete came into being as a new type of high-tech construction material in 1980's. For its desired properties including high strength, long durability and good workability, it has been shown remarkably economic in replacing traditional concrete structure and constructing special structure using in harsh environment. It has been prophesied that structure concrete with strength upwards of 1 OOMpa will be widely used.Concrete composition and structure are fundamental factors that affect its mechanical properties and durability. The basic route of preparing super high strength & high performance concrete is Portland cement added with fine mineral additive and super plasticizer. Therefore, composition and structure of super high strength & high performance concrete are different from ordinary concrete. By using of XRD, mercuiy intrusion porosimetiy, sorption isotherms, micro-hardness and so on, effects of ratio of water and binding materials and of type and content of fine mineral additives on composition, pore structure and interface structure have been studied in this paper. The results show that low ratio of water and binding materials together with fine mineral additive of different particle size distribution is an effective way to improve the properties of concrete.Besides the desired properties just mentioned, super high strength & high performance concrete must be of high volume stability. Due to high quantity and grade of cement, early shrinkage of super high strength & high performance concrete is larger than that of ordinary concrete. Therefore, how to compensate for its shrinkage has become an unavoidable and important problem that limits its utilization. Making use of traditional methods of compensating shrinkage, that is, added with appropriate expansion agent, compensating for the shrinkage of super high strength & high performance concrete has been realized. Moreover, the results indicate that the curing condition of this type concrete is very strict and it is necessary to strengthen its early curing in water.