Abstract
Ultra high strength concrete is composed of cement, pozzolanic material such as silica fume that shaped super fine particles and superplasticizer. These mixed proportions enable low water to binder ratio（W/B）, and extremely exact cement paste matrix is formed. It is thought that the low water to binder condition greatly affects on hydration of cement. In this research, we therefore examine the effect on hydration of cement at low W/B conditions, and focused on chain length distributions of silicate anions in calcium silicate hydrate（C－S－H）especially in this research. As a result of examining at W/B＝22％ with the mixed proportion of low heat Portland cement（LHC）partially substituted with silica fume（SF）, same behavior of hydration at W/B＝15％ was confirmed in some cases. The hydration of silicates（oligomerization of siloxane chains）was delayed by the deficiency of water that caused by the pozzolanic reaction of SF and water absorption of the fine aggregate.
