Research On Preparation And Performances Of The Fiber Reinforced Self-compacting High-strength Concrete

With the development of urbanization, concrete, as main a building material, is not only demanded to reach certain durability, but also demanded to reach high strength. High-strength is now becoming one of hot topics of application and development of concrete.It is showed in experimental results that a fatal flaw of high-strength is high brittle and shrinkage and deformation which will cause cracks easily. The brittle of high-strength can be lowed fundamentally by using ductility of steel fiber, then the requirements of structural forms, such as compressive strength, flexural strength and so on, can be met. At the same time, the concern of durability of high-strengh concrete can be removed by using steel fiber, which can reduce shrinkage and repress cracks.But in engineering pratice, the more steel fiber used, the less liqudility of concrete mixtrue. They are hard to be mixed and easy to be segregated and conglobated, which will cause mechanical property of concrete to be lowed. Then a kind of high-performance concrete matrix is needed eugently.Based on above aspects, this paper presents that steel fibre, high-strength and self-compaction can be integrated to be high-strength concrete with self-compaction steel fibre. All of the high strength of concrete, low brittle, reduction of shrinkage, high production efficiency, quick project progress, improved work environment can be realized by using high-strength concrete with self-compaction steel fiber. This has better environmental, social and economical benefits.In this paper effect on high-strength concrete with self-compaction steel fibre and properties is tested under different water-binder ratio, sand rate and mixed quantities of fiber to study and test preparation technology, mechanical property, shrinkage and deformation and durability, microstructure of high-strength concrete with self-compaction steel fiber. Through experimental test, conclusions are showed below,(1) The high-strength concrete with self-compaction steel fiber whose compressive strength is not less than 80Mpa and flexural strength is not less than 10Mpa, is produced through technological approaches, for example, low water-binder ratio to be less than 0.25 and mix micro steel fiber.(2) The shrinkage is determined by water-binder ratio and sand rate. The shrinkage of high-strength concrete with self-compaction steel fiber is the smallest under 0.22 water-binder ratio, 46% sand rate and can be reduced by mixing steel fiber.(3) The resistance of freezing of high-strength concrete with self-compaction steel fiber prepared in this experiment is well. After 300 times of freeze-thaw cycle, the elastic modulus is more than 95%,mass loss is less than 5%. The resistance of sulphate attacks can be advanced by mixing steel fiber.(4) The mercury porosimetry method (MPM) is used to analyze features of cement's pore-structure of super- high-strength concrete. It is found that pore-structure is improved with 0.22 water-binder ratio, 46% sand rate, which refine pore structure, reduce averaged pore size, raise the pores rate which is smaller than 20mm. It is found in SEM experiment that interface add steel fiber and high-strength concrete with self-compaction steel fiber bonds well.