Abstract: In order to study the mechanical and fracture properties of basalt fiber reinforced concrete (BFRC) of different types, the bundled and chopped basalt fibers (BFs) were used as reinforcing materials, and the concrete with coarse aggregate gradations of 5-10 mm and 16-20 mm, as well as 5-10 mm and 16-25 mm, was investigated. The cubic compressive strength, splitting tensile strength and prenotched three-point bending tests were carried out. The microstructure mechanism was analyzed by scanning electron microscope (SEM). The results show that the addition of BF significantly improves the splitting tensile strength, initial fracture toughness, unstable fracture toughness and fracture energy of concrete, but its compressive strength generally exhibits a downward trend. The compressive strength and split tensile strength of the bundled BFRC specimens are larger than those of the corresponding chopped BFRC specimens, demonstrating a better reinforcing effect of bundled BF on the strength properties of concrete. Moreover, the bundled BF has a better improvement effect on the unstable fracture toughness and fracture energy of concrete, and the values of the two indicators of the bundled BFRC specimens are 1.4 and 1.8 times higher than those of the chopped BFRC specimen. mens, respectively. However, the chopped BF shows a higher increment effect on the initial fracture toughness of concrete compared with the bundled BF, with the maximum increase reaching 8.7%. When the maximum coarse aggregate particle size increases from 20 mm to 25 mm, the compressive strength, unstable fracture toughness and fracture energy of the BFRC specimens present a rising trend, indicating that the specimens with larger coarse aggregate particle sizes have better mechanical and fracture properties. It can be concluded that the large-diameter bundled BF exhibits the best overall enhancing effect on the various properties of concrete with larger aggregate particle sizes.
Keywords: bundled basalt fiber; chopped basalt fiber; concrete; coarse aggregate gradation; mechanical property; fracture toughness
合肥工业大学学报自科版