Research On Preparation And Performance Of Self-compacting High-strength Concrete

Since the birth of concrete, because of its many advantages gradually become one of the most widely used man-made material. With the continuous of human architecture, the traditional concrete already can no longer meet the requirements of high-rise, super high-rise, super large-span, irregular structures and complex engineering. Therefore, the high-performance concrete has become the developing direction of the concrete technology. Compared with ordinary concrete, high-strength concrete has many advantage such as high strength and good durability. With the development of high strength concrete technology and widely used, the disadvantage are also gradually exposed. High-strength concrete is often needs more cementitious materials, the concrete has higher viscosity, and large autogenous shrinkage, which makes it difficult to cast and make concrete to cracks in the process of curing. Therefore, study how to overcome higher viscosity, large autogenous shrinkage, and cast difficulties of high-strength concrete is the focus of high strength concrete technology development. Compared with the disadvantage of high strength concrete. This paper study the preparation technology, the shrinkage performance and the durability and self-curing of self-compacting high-strength concrete. These technologies are used to prepare self-compacting, high-strength, low shrinkage, self-curing and high durability concrete. The main conclusions of this study are as follows:(1)Research the preparation technology of self-compacting high-strength concrete. The results show that after mixed with fly ash and slag can improve the workability and mechanical properties of concrete. Mixed with 5% silica fume can improve the workability and mechanical performance of concrete. The self-compacting high-strength concrete has good workability and mechanical properties, is produced through technological approaches, for example, change the water-binder ratio and sand ratio optimization. The optimization of the coarse aggregates gradation can reduce the concrete mix viscosity, improve the workability and mechanical performance.(2)By increasing water-binder ratio, and sand rate can reduce the autogenous shrinkage of concrete. Fly ash and expansive agent can significantly reduce the autogenous shrinkage of concrete. At 7 days, the autogenous shrinkage of the concrete mixed with 10%, 20%, and 30% fay ash are respectively 83.9%、72.9%, and 67.9% of that of concrete without fly ash. The autogenous shrinkage has respectively 12.9%, 41.8%, and 67.9% reduce than that of benchmark concrete when expansive agent is 6%, 9%, and 12%. High-strength concrete is compact in structure, so it difficult for water inside and outside the concrete to exchange, and the traditional way of supplying water from outside to cure the concrete cannot achieve good results. Self-curing materials can reduce the autogenous shrinkage of concrete. At 7 days, the autogenous shrinkage of concrete respectively mixed with 4% water carrier and pre-wet lightweight aggregates compared with benchmark concrete are respectively decreased by 19.4% and 15.3%.(3)The self-compacting high-strength concrete with a content of 2% zeolite powder as self-curing materials, can improve the slump-loss and has a little effect on the 28 days compressive strength. The durability of self-curing self-compacting high-strength concrete in this experiment is well. Adding zeolite powder can improve the durability of self-compacting high strength concrete. The experiment results show that zeolite powder can reduce the autogenous shrinkage of concrete. At 7 days, the autogenous shrinkage of concrete respectively mixed with 2% zeolite powder compared with benchmark concrete are decreased by 17.9%. The electric flux of concrete decreased by 20.1% when adding zeolite powder is 2%. The Sulfate corrosion resistance coefficient of concrete by 82.4% to 87.1% after 150 times wetting-drying cycles. After 28 times freeze-thaw cycling test, the exfoliation mass per unit area decreased by 29.3% and the relative dynamic elastic modulus increased by 4.9%. The results show that the zeolite powder can improve the durability of concrete.