Experimental Study On Crack Control Of Reinforced Steel-polypropylene Hybrid Fiber Concrete

In view of the crack problems exposed during the operation of reinforced concrete structures,this paper considers adding steel-polypropylene hybrid fibers to concrete to improve the tensile properties of concrete,and carries out the research on crack control of reinforced steel-polypropylene fiber concrete.Based on the research,the formula for calculating the crack width of reinforced steel-polypropylene hybrid fiber concrete is deduced.Based on the existing research on reinforced steel fiber reinforced concrete,the crack width calculation formula suitable for reinforced steel-polypropylene hybrid fiber reinforced concrete is deduced.The axial tension test is designed to study the influence of fiber incorporation on crack morphology,crack spacing and crack width,and the deduced crack width calculation formula is revised.Combining with the existing theoretical research,crack resistance mechanism of reinforced steel-polypropylene fiber concrete is explored.The main research contents and methods are as follows:1.On the basis of the existing formula for calculating the crack width of reinforced steel fiber reinforced concrete,considering the influence of polypropylene fiber incorporation,the formula for calculating the crack width of reinforced steel-polypropylene hybrid fiber reinforced concrete is derived.2.Based on the structural and mechanical characteristics of reinforced concrete,the axial tension test and auxiliary test of reinforced steel-polypropylene fiber reinforced concrete are designed,and the specimens form,clamping mode and test batch are determined.In view of the test process,the specimen forming,reinforcing bar and specimen processing methods are put forward.According to the test requirements,the loading mode is determined,and the testing machine and data acquisition system are selected.Aiming at the test difficulties,such as eccentricity and fiber agglomeration,solutions are proposed.The test data of steel stress,crack spacing and crack width of reinforced concrete specimens are measured.3.The phenomenon of axial tension test of reinforced steel-polypropylene hybrid fiber concrete specimens is described in detail.The effect of fiber content on cracking load of concrete is studied,and the crack development process of specimens is observed.The influence of fiber content on crack morphology is analyzed,and the relationship between steel stress and crack width is discussed.The influence of parameters on crack width,and the formula for calculating crack width is revised according to the test results.Combining the existing theory,the tensile failure mechanism of reinforced steel-polypropylene fiber reinforced concrete is explored.