关键词: 纤维增强混凝土, 力学性能, 破坏形态, 玄武岩纤维, 减水剂与硅灰

Abstract: In order to investigate mechanical properties and failure features of different fiber-reinforced concrete, specimen tests were carried out to compare the effects of different fiber volume fractions on compressive strengths, splitting tensile strengths and modulus of elasticity. Five different types of fiber-reinforced concrete were evaluated involving basalt fibers, carbon fibers, steel fibers, polypropylene fibers and the hybrid of basalt and polypropylene fibers. More attentions were focused on the basalt fiber-reinforced concrete. The effects of superplasticizer and silica fume on the mechanical properties of basalt fiber-reinforced concrete were further discussed. The test results demonstrate that the 0.05%~0.2% volume fraction addition of basalt fibers improved the splitting tensile strengths, as well as the integrity of the damaged specimens. However, the cubic and axial compressive strengths of basalt fiber-reinforced concrete decreased with the increase of the volume fraction. On the other hand, under the precondition of an identical volume fraction, polypropylene fibers mostly contributed to the splitting tensile strengths of concrete since all the fibers presented a satisfactory anti-cracking effect. However, all the 5 types of fibers show little effects on modulus of elasticity and caused adverse effects the compressive strengths. With respect to the basalt fiber-reinforced concrete, superplasticizer commonly used in engineering could weaken the bonding interfaces between fibers and concrete, resulting in worse mechanical properties. Fortunately, this influence could be improved by adding silica fume.

Key words: fiber-reinforced concrete, mechanical properties, failure features, basalt fiber, superplasticizer and silica fume