Experimental Study On Impact Performance Of Hybrid Fiber Reinforced Concrete

Impact resistance is one of the important performance indexes of concrete materials under dynamic load.Existing studies have shown that: adding a certain volume of steel fibers into concrete can enhance the impact resistance of concrete;steel fiber and synthetic fiber hybrid reinforced concrete has excellent static mechanical properties.However,there is not much research on the impact properties of synthetic fiber and steel fiber reinforced concrete.and the existing research results are not uniform due to the different test equipment and methods used by different researchers,which makes the impact performance test results more discrete.Therefore,improving the impact test device to reduce the dispersion of test results and studying the impact resistance of steel fiber and synthetic fiber hybrid reinforced concrete have important theoretical significance and practical value for improving the safety performance of concrete structures under dynamic loads.In this paper,ultra-short microfilament steel fiber,multi-anchor steel fiber and polypropylene fiber and blast furnace slag powder are mixed into concrete,and C50 grade hybrid fiber reinforced concrete with a total fiber content of not more than 1.5% is prepared.The basic mechanical properties and anti-impact performance tests were conducted.The main research work and results are as follows:(1)Experimental study on basic mechanical properties of hybrid fiber reinforced concrete.6 groups of ultra-short microfilament steel fibers with different fiber ratios,multi-anchor steel fibers(volume content 0.8%,1.2%)and polypropylene fibers(volume content 0.11%)are mixed and mixed to enhance high performance The basic mechanical properties of concrete specimens were tested,and the influence of compressive strength and splitting tensile strength of two steel fibers and polypropylene fibers after mixing was studied.(2)Experimental research on HFRC impact performance.Through the improved ACI544 drop weight impact test device,the drop weight impact test research of single short ultra-fine fiber steel fiber concrete(SFRC)and steel-polypropylene hybrid fiber reinforced concrete(HFRC)was carried out.The influence of the content and type of steel fiber and the hybrid effect of steel fiber and polypropylene fiber on the impactresistance of concrete was studied;the positive hybrid effect of two types of steel fiber and polypropylene fiber and the optimal impact resistance were analyzed.Fiber ratio.(3)Analysis of impact life based on Weibull distribution.By comparing the test results of different SFRC and HFRC test groups,the impact of the improvement and optimization of the test equipment on the dispersion of the test data is analyzed;the kurtosis coefficient and skewness coefficient are calculated to study the distribution law of impact life.The data fitting analysis of the initial cracking impact times and final cracking impact times obtained from the test verifies the applicability of the two-parameter Weibull distribution model: and fits and analyzes the impact life estimation results and actual test results under different failure probabilities.Consistency provides a theoretical basis for further research on the impact failure of concrete.(4)Impact damage analysis based on Weibull distribution.Impact damage analysis was performed based on the Weibull distribution statistical damage model,and the impact life damage evolution equations of SFRC and HFRC were established respectively.