Study On Mechanical Properties Of The Freeze-thaw Cycle Under The Action Of Steel Fiber Reinforced Concrete

In cold regions of northern China, due to the positive and negative temperature climate change produced by the alternation, the freeze-thaw damage of concrete structures has become one of the major diseases, serious impact on the safety and long-term operation of the concrete structure. The frost resistance of concrete is one of the important index to evaluate the durability of concrete, freeze-thaw cycle effect will lead to a serious decline in the long-term durability of concrete, mechanical properties and concrete will have a severe recession. But in the concrete mixed with proper amount of steel fiber can improve the frost resistance of concrete, and improve the steel fiber concrete in freeze-thaw cycle under the action of mechanical properties. With the rapid development of China’s national economy, the application of steel fiber reinforced concrete has been popularized gradually. Therefore, it has very important meaning of freezing and thawing on mechanical properties of steel fiber reinforced concrete under cyclic loading.In this paper, through theoretical analysis and experimental study, the main contents are as follows:1, This paper made of fiber content was 0, 0.75% of steel fiber reinforced concrete, 1.5% specimens of concrete specimens, and the freeze-thaw cycle test, were 0 times, 50 times, 100 times, 150 times and 200 times of freeze-thaw cycle, the freeze-thaw cycle every 50 times, measure once the concrete quality loss and dynamic elastic modulus, and draw the curve of freeze thawing cycles, the relative dynamic elastic modulus and mass loss. The results show that, with the content of steel fiber to improve the anti erosion ability increases, concrete, steel fiber in concrete after toughening, crack resistance effect.2, after the freeze-thaw cycle test, compressive strength test cube and prism test of bending strength of steel fiber reinforced concrete in freezing and thawing of the specimen, observation of concrete compressive strength, failure mechanism and the flexural strength of specimen data, draw the different content of steel fiber concrete compressive strength, the flexural strength and freezing and thawing cycles of the curve, analysis of volume content of steel fiber and the effect of freezing on the mechanical properties of concrete freeze-thaw cycles. The results show that, at the initial stage of freezing and thawing, the incorporation of steel fiber have great influence on concrete compressive strength, flexural strength, but with the number of freeze-thaw cycles increasing, the effect of steel fiber on the compressive, flexural strength is smaller, the more cycles of freezing and thawing, the compressive strength, flexural strength loss is bigger.3, Through the above experimental results and theoretical analysis, the influence of the steel fiber mixed with antifreeze of concrete durability, and analysis of the mechanism of freeze-thaw damage of steel fiber reinforced concrete, the freeze-thaw damage model is established, in order to establish the frost resistance durability of steel fiber reinforced concrete performance indicators.