Of C60 High-performance Concrete Creep Study

In order to guarantee the smooth and secure of train movements, high-speed railway bridge camber is stringently restricted. This paper is based on Guangzhu Intercity traffic engineering Ronggui bridge project. for the purpose of Ronggui bridge construction control and prediction of the latter part of creep deformation, provides reinfoned performance, shrinkage and creep performance and prestressed concrete girder creep performance is studied in this paper. This primarily work and achievements of the paper is as follows:1. The flyash and slag on the impact of the concrete strength is studied. Result shows: Flyash and slag in water - reducing effect has an "hyper - stromatolite effect",and the water - reducing effect of flyash is better than the slag. Concrete early strength is only related to water - cement ratio and post-strength related to water-binder ratio and total cementitious materials. The concret post- strength is increased as the the amount of the flyash is higher. In a range of high - flyash, fly ash on concrete brittle improvement is increase as the the amount of the flyash is higher, beyond, fly ash on concrete brittle improvement on the contrary, may be reduced.2. Concret creep performance are experimental studied under the standard condition. The measured data and the results of theoretical model is comparative analysised. The creep coefficient of concrete with fly ash and slag is far less than the creep coefficient of same level of ordinary concrete . the added load only has a lower impact on the early part of creep development while has no effect of latter part. In the high - performance concrete with certain amount of slag, in range of amount of fly ash, concrete creep performance will be going well when the amount of fly ash increased , when the amount of fly ash exceeds a certain limit, concrete creep performance will reduced . In this test conditions, in order to make concrete creep optimal, fly ash volumefly at 100kg/m~3. When fly ash volumefly in 0 - 20%, concrete shrinkage strain is reduced as the amount of flyash increased, when the flyash volumefly more than 20% , oncrete shrinkage strain is increased.The measured creep coefficient is always less than the creep coefficient calculated by two creep model CEB-FIP (1978) and CEB-FIP (1990). The creep coefficient calculated by creep model is larger than measured data. The existing specification cannot effectively forecast fly ash and slag concrete's long-term creep.3. The camber of prestressed concrete beams is measured and researched. The camber is increased(decreased) as the temperature is increased(decreased). The loading time of 2-term load can effect the camber. The camber reduced more and the post-term camber is less when the loading time is earlier. The time of pre-stress cable tension can obviously effect the camber. The camber is bigger when the time of pre-stress cable tension is earlier. In order to control the camber, the time of pre-stress cable tension should be earlier and when the time of pre-stress cable tension is fixed, loading time of 2-term load should be earlier.