束状玄武岩纤维增强混凝土力学性能试验研究

Experimental study on mechanical properties of bundled basalt fiber reinforced concrete

  • 摘要: 为研究束状玄武岩纤维(Bundled Basalt Fiber, BBF)增强混凝土的力学性能,对不同纤维长度(12 mm、18 mm、24 mm)、体积掺量(0.1%、0.2%、0.3%)和类型(束状玄武岩、短切玄武岩和聚丙烯)的纤维增强混凝土进行立方体抗压、劈裂抗拉和断裂韧性试验,并通过扫描电镜观察了其微观结构。结果表明:BBF对混凝土抗压强度提升效果不明显;而对劈裂抗拉强度增强效果显著,在纤维长度为24 mm,体积掺量为0.2%时,抗拉强度最大提高幅度为26.65%;随纤维增强指数(Reinforcement Index, RI)增加,BBF混凝土拉压比呈升高趋势,且RI为24时,拉压比为普通混凝土(Normal Concrete, NC)的1.39倍;BBF的掺入显著提升了混凝土三点弯曲峰值荷载、起裂韧度及失稳韧度,且当掺量为0.3%,纤维长度为12 mm时,三者较NC最大提升幅度分别为53.66%、47.06%及151.03%。电镜扫描显示BBF表面附着大量水化产物,与水泥浆体粘结紧密且与基体间无明显界面过渡区,有效抑制了微裂缝扩展连通。

     

    Abstract: In order to study the mechanical properties of bundled basalt fiber (BBF) reinforced concrete, cube compressive strength, splitting tensile strength and fracture toughness experiments of fiber reinforced concrete with different fiber lengths (12 mm, 18 mm, 24 mm), volume fraction (0.1%, 0.2%, 0.3%) and types (bundled basalt, chopped basalt and polypropylene) were carried out. And the microstructure was observed by scanning electron microscopy. Results show that the effect of BBF on compressive strength of concrete is not obvious; when the fiber length is 24 mm and the dosage is 0.2%, the maximum increase of tensile strength is 26.65%. With the reinforcement index (RI) increases, the tension-compression ratio of BBF concrete tends to increase, and when RI gets to 24, the tension-compression ratio is 1.39 times that of NC. Incorporation of BBF generally increases three-point bending peak load, initiation toughness and unstable toughness of concrete, in which the maximum increase rate at 0.3% are 53.66%, 47.06% and 151.03%, respectively. Scanning electron microscopy shows that a large number of hydration products are attached to surface of BBF, which are closely bonded to cement paste and have no obvious interface transition zone with matrix, effectively inhibiting propagation of micro-cracks.

     

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