多尺度纤维增强水泥基材料的性能及机理研究

发布时间：2018-05-23 20:55

本文选题：水泥基材料 + 聚丙烯粗纤维　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：水泥基材料自身的结构层次及其破坏过程均体现出较为显著的多尺度特征,针对这一特征,采用大尺寸-低弹模的聚丙烯粗纤维(PPCF)和小尺寸-高模量的玄武岩纤维(BF)设计了一种多尺度纤维增强水泥基材料(MSFRCC),以期在相应层次、相应阶段实现层层阻裂,进而对水泥基材料的性能进行整体增强。首先对MSFRCC的基本力学性能展开研究,综合考虑增强系数和混杂系数,分析单掺PPCF或BF及混掺PPCF/BF对MSFRCC的抗折强度、抗压强度以及劈裂抗拉强度的影响,确定PPCF和BF各自的合理掺量范围。在确定纤维掺量范围后,着重研究了单掺PPCF、混掺PPCF和BF以及不同长径比的BF分别对MSFRCC的弯曲韧性、冲击韧性、抗冻性能以及抗盐冻性能的影响,根据试验结果对各性能进行分析评价,并对纤维作用机理进行分析。研究结果表明,单掺PPCF时,随着纤维掺量的提高,水泥砂浆的峰值荷载、初裂挠度、弯曲韧性指数均先增大后减小,冲击韧性指标呈增大趋势,抗冻性呈降低趋势,抗盐冻性则先提高后降低;PPCF掺量为0.50%时,水泥砂浆的峰值荷载和初裂挠度最大,抗盐冻性最好。PPCF和BF混掺时,固定PPCF掺量为0.50%,随着BF掺量增加,MSFRCC的峰值荷载、初裂次数呈增大趋势,初裂挠度、弯曲韧性指数、延性指标先增大后减小,抗冻性和抗盐冻性均有所提高,BF的掺量为0.10%时,MSFRCC的初裂挠度值、弯曲韧性指数以及延性指标最大;固定BF掺量为0.10%,随着PPCF掺量增加,MSFRCC的峰值荷载呈减小趋势,弯曲韧性指数呈增大趋势,抗冻性能呈降低趋势,抗盐冻性则先提高后降低,PPCF的掺量为0.50%时,MSFRCC的延性指标最大,抗盐冻性最好;固定PPCF、BF掺量分别为0.50%、0.10%,随着BF长径比增加,MSFRCC的峰值荷载、初裂挠度、弯曲韧性指数和延性指标均先增大后减小,抗冻性能先提高后降低,抗盐冻性呈增大趋势,BF的长径比为923时,试件的峰值荷载、初裂挠度、弯曲韧性指数以及延性指标均最大,抗冻性能最好。综合评价MSFRCC的各项性能,给出的最佳混掺方案为:PPCF的掺量为0.50%,BF的掺量为0.10%,BF的长径比为923。
[Abstract]:The structure level and failure process of cement based materials all show more obvious multi-scale characteristics, in view of this characteristic, A multi-scale fiber reinforced cement-based material, MSFRCCG, was designed by using large size low elastic modulus polypropylene coarse fiber (PPCF) and small size high modulus basalt fiber (BFF), in order to achieve layer by layer crack resistance at the corresponding level and stage. Furthermore, the properties of cement-based materials are strengthened as a whole. Firstly, the basic mechanical properties of MSFRCC are studied. The effects of PPCF or BF and mixed PPCF/BF on the flexural strength, compressive strength and splitting tensile strength of MSFRCC are analyzed. The reasonable range of PPCF and BF are determined. After determining the range of fiber content, the effects of single doped PPCF, mixed PPCF and BF with different aspect ratio on the flexural toughness, impact toughness, freezing resistance and salt freezing resistance of MSFRCC were studied. According to the experimental results, the properties of the fiber were evaluated and the mechanism of fiber action was analyzed. The results show that with the increase of fiber content, the peak load, initial crack deflection and flexural toughness index of cement mortar increase first and then decrease, the impact toughness index increases and the frost resistance decreases with the increase of fiber content. The peak load and initial crack deflection of cement mortar were the largest when the salt freezing resistance was first increased and then decreased to 0.50. When the salt freezing resistance was the best, the fixed PPCF content was 0.50. With the increase of BF content, the peak load of PPCF was increased. The initial crack deflection, flexural toughness index and ductility index increased first and then decreased. The initial crack deflection value, flexural toughness index and ductility index of MSFRCC were the largest when the content of initial crack deflection and salt freezing resistance was 0.10. The fixed BF content is 0.10, with the increase of PPCF content, the peak load of MSFRCC decreases, the flexural toughness index increases, the freezing resistance decreases, and the salt freezing resistance increases first and then decreases the ductility index of MSFRCC, when the content of PPCF is 0.50, the ductility of MSFRCC is the largest. The content of fixed PPCFN BF was 0.500.10. With the increase of BF aspect ratio, the peak load, initial crack deflection, flexural toughness index and ductility index of MSFRCC increased first and then decreased, and the frost resistance first increased and then decreased. When the ratio of length to diameter of BF is 923, the peak load, initial crack deflection, flexural toughness index and ductility index are the largest, and the freezing resistance is the best. According to the comprehensive evaluation of the properties of MSFRCC, the optimum mixing scheme is that the ratio of length to diameter of MSFRCC is 0.50 and the ratio of length to diameter is 923.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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