纤维束-自应力混凝土界面黏结性能试验及参数化计算方法

Experiment and parametric calculation method of fiber bundle-self-stressing concrete interface bonding properties

  • 摘要: 纤维增强自应力混凝土具备高抗裂、抗弯和韧性的优秀性能表现,但两相材料间复杂的脱黏破坏模式严重限制材料协同承载。因此,为建立统一的黏结性能表征方法,本文设计了全过程刚性约束的拉拔试验,测试了高自应力状态下不同纤维细度(取1000米长纤维在公定回潮率下的重量克数,单位为Tex)玄武岩和耐碱玻璃纤维束的界面行为。基于宏观力学现象与能量平衡关系,剥离尺寸效应影响,提出了以界面黏结层临界能量释放率Gc为核心指标的参数化计算方法。研究结果表明,随着Tex的增加,宏观拉拔强度提高,破坏形式发生拉断-拔出-脱丝的规律演变,在同Tex下,耐碱玻璃纤维束的界面黏结与整体性均优于玄武岩纤维束。按所建方法计算,耐碱玻璃纤维束与基体之间的Gc较玄武岩纤维束提高约318.7%,同种纤维内不同Tex的Gc离散度低于13.6%,验证了该方法在材料对比与参数识别方面的可行性。

     

    Abstract: Textile reinforced self-stressing concrete exhibits superior performance of high crack resistance, bending resistance and toughness, but the complex debonding failure mode between two-phase materials seriously limits the synergistic bearing of materials. Therefore, in order to establish a unified bonding performance characterization, this paper designed a whole-process rigid constraint pull-out test to test the interface behavior of basalt and alkali-resistant glass fiber bundles with varying fiber fineness (defined as the weight in grams per 1000 meters of fiber at standard moisture regain, measured in Tex) under high self-stress conditions. Based on the relationship between macroscopic mechanical phenomena and energy balance, and the influence of peeling size effect, a parametric calculation method with the critical energy release rate Gc of the interfacial bonding layer as the core index was proposed. The results show that with the increase of Tex, the macroscopic pull-out strength increases, and the failure mode evolves from break, pull-out, defiber. Under the same Tex, the interfacial bonding and integrity of alkali-resistant glass fiber bundles are better than those of basalt fiber bundles. According to the established method, the Gc between the alkali-resistant glass fiber bundle and the matrix is about 318.7 % higher than that of the basalt fiber bundle, and the Gc dispersion of different Tex in the same fiber is less than 13.6 %, which verifies the feasibility of the method in material comparison and parameter identification.

     

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