Mixture And Application Of Self-Compacting Concrete-Filled Steel Tubes Prepared From Manufactured Sand

The concrete filled steel tube (CFST) arch bridge has been widely concerned by the bridge construction fields for its lightweight structure, strong spanning ability, constructability, higher cost performance. However, the key factors for the success of CFST is to prepared a kind of core concrete that can keep a good coordination with the steel tube. And the first task is to keep stell tube compacting and filling well with the core concrete, hence the self-compacting concrete is a good and essential choice. As a kind of economical and environmental engineering materials, the manufactured fine aggregate (MFA) has solve many problems on the lack of river sand, the difficulty of transportation and the accumulation as well as the pollution of the stone chips in the construction of the mountain district. However, the high content of stone fine, the poor grain and the bad gradation for MFA have restricted its application in SCC. Hence it will be more challenging to attempt a research on the application of MFA for SCC that could easily filled the CFST, and which no doubt will gain fine economic and social benefit, and all these are approved by our society.Based on the project of Xiao He bridge in Hu Rong freeway, the feasibility of C60 self-compacting and Steel tube concrete that produced by MFA has been demonstrated, and we also put forward the application technology for MFA with high content stone fine to prepared the self-compacting steel tube concrete though this article, which will be a good example for the engineering application of MFA. Specifically, we have done the following jobs.1. Combined with practical engineering background and the property of materials, the requirements of technology of C60 Steel tube concrete produced by MFA, and the key technical target of raw materials have been posed.2. The best materials have been selected through the material choice test. And then, we optimized mix of concrete, though the study on the influence of water-binder ratio, amount of binding materials, the stone fine content of MFA, sand ratio, the species and volume of expansion agent and mineral admixtures to the workability, compressive strength, limited expansion of the C60 concrete.3. The workability, mechanical performance, volume stability, hydration heat,and durability of the postoptimality mix has tested. The influence of stone fine content that range from 3% to 10% of MFA to the workability, mechanical performance, limited expansion, creep and shrinkage and durability of concrete has been systematically studied, and the corresponding contrast experiment of river sand concrete has also been studied. And the result show that the C60 Steel tube high performance concrete that prepared by MFA with stone content of 7% could obtain better performance in mechanical performance, limited expansion and durability, although a little poor in workability, compared to the river sand concrete.4. Pouring arrangements of C60 Steel tube concrete produced by MFA has been investigated through the engineering application. The results showed that the concrete have a good workability and strength, and filled the steel tube well.