Abstract:

Under the influence of factors such as temperature changes and shrinkage deformation， concrete， due to its low tensile strength， is prone to cracking under small tensile stress， which affects the normal use and durability of the structure. To enhance the tensile strength and energy absorption capacity of concrete materials， the influence of different fiber contents on the tensile properties of concrete is studied and analyzed. Three different types of fibers， steel fiber （SF）， polypropylene fiber （PPF）， and polyvinyl alcohol fiber （PVAF）， were used to compare the tensile properties of concrete under different fiber types and their dosages， and to explore the optimal fiber dosage. When preparing concrete samples， materials such as cement， silica fume， and fly ash are selected as matrix raw materials， and three different types of fibers are added at mass fractions of 0%， 0.5%， 1.0%， 1.5%， 2.0% and 2.5%， respectively. By conducting tensile performance tests on the samples， analyze different strength indicators of the samples. The results indicate that the tensile performance of the sample is strongest when the content of different fibers is 2.0% by mass. When 2.0% steel fiber is added to the three types of fibers， the tensile strength reaches 9.63 MPa， and the initial and post crack strength remain at a high level. The energy absorption capacity per unit volume reaches between 2.1 and 2.4 kJ/m3. The reinforcement effect of PVAF is second， with a tensile strength of 8.81 MPa at a dosage of 2.0%. The reinforcement effect of PPF is relatively weak， with a tensile strength of only 7.82 MPa at a dosage of 2.0%. Therefore， the concrete sample with 2.0% SF added exhibited good tensile strength， providing effective guarantee for the performance improvement of concrete materials in practical applications.

Key words: Fiber doping, Concrete, Tensile strength, Steel fiber, First crack strength