Study On The Reinforcing Mechanism Of Steel Fiber And Its Application In Expansive Concrete

Steel fiber reinforced expansive concrete is a new building material which has good mechanical performance and permeability resistance. It is expected to be used in hydraulic structure and rock-filled dams. At present, the study in this field is still in its primary development period in our country, and there is little further research references abroad until now. The paper is concentrated on the fundamental mechanical performance and applications of steel fiber reinforced expansive concrete. The main contents of my project are as follows. Systematic experimental study and theoretical analysis have been performed on the expansion and shrinkage property, fundamental mechanical performance, characteristic bf tension and compression of the material. Based on the results, the mathematical expression of expansion and shrinkage process, strength calculation formula of steel fiber reinforced expansive concrete, bond strength calculation expression of the concrete and deformed reinforcement, and strain- stress curve have been presented. Based on the test results, study on the reinforcing mechanism of steel fiber in expansive concrete has been carried out. It is believed two kinds of reinforcement should be expressed in the strength formula of steel fiber reinforced expansive concrete. One is the reinforcement of the limited expansion, another is of the anti-crack. According to the principle of ?conservation of power and energy?, a strength expression which is linked with the strength expression of steel fiber reinforced concrete is worked out. For convenient usage in engineering, the simplified expression of strength has been given, on the test condition and results ,which shows good agreement with the test results. Typical pipes in practice have been selected in the paper as specimen models of steel fiber. expansive reinforced concrete, because concrete water transfer pipes demand to have good crack and permeability resistance. Systematic experimental and analytical studies have been carried out on mechanical and deformation characteristic under internal pressure for steel fiber reinforced expansive concrete pipes, reinforced pipes of using steel fiber reinforced concrete and of using steel fiber reinforced expansive concrete and steel fiber reinforced auto-stress concrete pipes. Computational method for the auto-stress value of II steel fiber reinforced auto-stress concrete pipes and calculating formula to predict the crack resistance capacity under internal pressure of testing pipes have been given. The economic of steel fiber reinforced auto-stress concrete pipe and steel fiber expansive concrete pipe has been compared with that of others. And the results show that both kinds of pipes have good performance, and their application will bring considerable economical and social benefits.