Abstract
Based on the experiment, the effects of elevated temperature (25 ℃, 200 ℃, 300 ℃, 400 ℃, 500 ℃) and fiber types (SC, CFC, BFC, PPFC, SFC) on the pore structure and dynamic mechanical properties of concrete materials were investigated. The test results show that: (1) Compared with the porosity of specimens at 25 ℃, the porosity of plain concrete at 200 ℃, 300 ℃, 400 ℃ and 500 ℃ increases by 14.53%, 26.59%, 45.36% and 81.23%, respectively. Elevated temperature increases the porosity of the specimen, and the addition of fiber can reduce the porosity and porosity complexity of the specimen. (2) At 25 ℃, the peak stress of CFC, BFC, PPFC and SFC specimens is 1.44, 1.37, 1.13 and 1.17 times that of plain concrete, and the toughness increase of CFC, BFC, PPFC and SFC specimens is 127.78%, 96.30%, 83.33% and 59.26%, respectively. The addition of fiber can significantly improve the strength and toughness of concrete. (3) Fiber incorporation reduces the energy dissipation effect of concrete specimens, and elevated temperature enhances the energy dissipation effect of concrete specimens. The effect of elevated temperature makes the concrete material deteriorate, and its plastic deformation and damage degree are higher under the impact load. (4) The five kinds of fiber reinforced concrete show the coexistence mode of tensile failure and compressive failure under impact load. The addition of fiber reduces the damage degree of concrete specimens to different degrees, and CF has the best effect on the impact resistance of concrete materials. The research results can provide experimental basis for elevated temperature resistance and dynamic load resistance of different fiber concrete buildings.