Abstract
To discuss the mechanical properties of concrete with different steel fiber content. Two grades of concrete were prepared, and the effects of different content and length of steel fiber on slump, pore structure, compressive strength, splitting strength, flexural toughness and impact resistance of concrete were studied. the fluidity of steel fiber reinforced concrete decreases with the increase of steel fiber content, and the concrete with long steel fiber decreases more than that with short steel fiber With the increase of steel fiber content, the compressive strength, splitting strength, bending toughness and impact resistance of steel fiber reinforced concrete are improved to varying degrees. The splitting tensile strength increases fastest when the volume content of steel fiber is 1.0%~1.5%, and the flexural strength increases fastest when the volume content of steel fiber is 1.0%~2.5%. When the fiber is stressed, it gives full play to its strong tensile capacity and shares the tensile force for concrete materials. According to the comprehensive economy, the optimum steel fiber content is 2% ~ 3%, which provides the basis for subsequent experimental research and construction production.
Highlights
Because of the low tensile strength of concrete, cracks will appear in the tensile zone of concrete structure, which will accelerate the carbonization of concrete, and the bearing capacity and service life of concrete structure will decrease with the expansion of cracks [1]
Algburi et al [7] carried out a basic mechanical test research on steel fiber reinforced concrete with steel fiber volume content of 0%, 0.75% and 1.0%, and pointed out that steel fiber can enhance the modulus and strength of concrete; Relevant data [8, 9] shows that the compressive strength of steel fiber reinforced concrete with 1% ~ 2% volume ratio increases by 10% ~ 30% compared with matrix concrete
TEST RESULTS AND DISCUSSION 3.1 Test Result Compressive strength of concrete cube is calculated according to equation (1), and splitting tensile strength is calculated according to equation (2) [12]: ffcccc where ffcccc is the compressive strength of concrete cube specimen (MPa); fftttt is splitting tensile strength (MPa); FF is the failure load of the specimen (n); AA is the bearing area of the specimen
Summary
Because of the low tensile strength of concrete, cracks will appear in the tensile zone of concrete structure, which will accelerate the carbonization of concrete, and the bearing capacity and service life of concrete structure will decrease with the expansion of cracks [1]. Steel fiber reinforced concrete has the advantages of high tensile strength, bending strength and shear strength, and can significantly improve the crack resistance, toughness, impact resistance and durability of concrete [2, 3]. Fu et al [10] used the morphology analysis method to link the difference of steel fiber number on different fracture surfaces with the mechanical properties and anisotropy of SFRC and found that flexural toughness index and bearing capacity change coefficient of steel fiber reinforced high-strength concrete increased with the increase of steel fiber volume ratio. In the process of composite material formation and stress failure, steel fiber can effectively reduce the strength factor of the stress field at the crack tip, restrict the development of micro-cracks and block the generation of macro cracks, achieving the effect of strengthening and toughening concrete matrix
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