Study On The Frost Resistance Of Steel Fiber Reinforced Concrete

In cold regions, the concrete freezing and thawing destruction is one of the most primary causes of our concrete structure aging and disease, which affects the long-term use and the safe operation of the concrete building seriously. Decrease of durability of concrete structure due to freeze-thaw cycles showed the emergence and development of cracks in concrete finally. Incorporation of steel fibers in concrete is the effective way to improve crack resistance of concrete. With the development of China's economy and technology, the application of steel fiber reinforced concrete (SFRC) has been gradually promoted. Therefore, it is great significant to research the freeze and thaw durability of SFRC.Basic experimental research that combine the action of freezing-thawing cycles and deicing salt to SFRC was conducted in this paper. In the experiment, the volume fraction of steel fiber and number of freeze-thaw circulation are taken as variable parameter. Based on the different numbers of freeze-thaw circulation, weight losing,splitting strength and dynamic modulus of elasticity of SFRC (0%,0.5%,1.0%,1.5%,2.0%) were measured. In order to discuss the impact of freeze-thaw cycles on microstructure of SFRC from the microstructure, this paper focuses on the application of the scanning electron microscope (SEM) in observations of the microcrack characteristics of concrete at different freeze-thaw cycles.Through analysis of test results, the reinforced mechanism of the SFRC under the action of freeze-thaw was analyzed. On the basis of the microstructure, the damage mechanism of SFRC under action of freeze-thaw was discussed. It has been found out that failure of SFRC in salt solution was much greater than in water. The reinforced actions of steel fiber on splitting strength of concrete are notable and the influence of steel fiber volume fraction on the frost-resisting property is obvious. The effects of steel fiber with proper volume fraction can inhibit the peeling of the concrete and reduce its damage rate. The best performance of SFRC can be got when the steel fiber quantity is 1.5%.