The effects of polyvinyl alcohol (PVA) fiber content on mechanical and fracture properties of geopolymer concrete (GPC) were investigated in the present study. Mechanical properties include cubic compressive, prism compressive, tensile and flexural strengths, and elastic modulus. The evaluation indices in fracture properties were measured by using the three-point bending test. Geopolymer was prepared by fly ash, metakaolin, and alkali activator, which was obtained by mixing sodium hydroxide and sodium silicate solutions. The volume fractions of PVA fiber (length 12 mm and diameter 40 μm) were 0, 0.2, 0.4, 0.6, 0.8, and 1.0%. The results indicate that the effects of the PVA fiber on the cubic and prism compressive strengths and elastic modulus are similar. A tendency of first increasing and then decreasing with the increase in the PVA fiber content was observed in these properties. They all reached a maximum at 0.2% PVA fiber content. There was also a similar tendency of first increase and then decrease for tensile and flexural strengths, peak load, critical effective crack lengths, fracture toughness, and fracture energy of GPC, which were significantly improved by the PVA fiber. They reached a maximum at 0.8% PVA fiber content, except the tensile strength whose maximum was at 1.0% PVA fiber volume fraction. Considering the parameters analyzed, it seems that the 0.8% PVA fiber content provides optimal reinforcement of the mechanical properties of GPC.

中文翻译：

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PVA纤维对粉煤灰地质聚合物混凝土力学性能的影响

本研究研究了聚乙烯醇 (PVA) 纤维含量对地质聚合物混凝土 (GPC) 力学和断裂性能的影响。机械性能包括立方压缩、棱柱压缩、拉伸和弯曲强度以及弹性模量。断裂特性的评价指标通过使用三点弯曲试验来测量。地聚合物由粉煤灰、偏高岭土和碱活化剂制成，由氢氧化钠和硅酸钠溶液混合得到。PVA 纤维（长 12 毫米，直径 40 微米）的体积分数分别为 0、0.2、0.4、0.6、0.8 和 1.0%。结果表明，PVA纤维对立方和棱柱压缩强度和弹性模量的影响是相似的。在这些性能中观察到随着PVA纤维含量的增加先增加然后减少的趋势。它们都在 PVA 纤维含量为 0.2% 时达到最大值。GPC的拉伸和弯曲强度、峰值载荷、临界有效裂纹长度、断裂韧性和断裂能也有类似的先增加后减少的趋势，PVA纤维显着改善了这些趋势。它们在 PVA 纤维含量为 0.8% 时达到最大值，但拉伸强度在 PVA 纤维体积分数为 1.0% 时达到最大值。考虑到所分析的参数，似乎 0.8% 的 PVA 纤维含量为 GPC 的机械性能提供了最佳增强。GPC的拉伸和弯曲强度、峰值载荷、临界有效裂纹长度、断裂韧性和断裂能也有类似的先增加后减少的趋势，PVA纤维显着改善了这些趋势。它们在 PVA 纤维含量为 0.8% 时达到最大值，但拉伸强度在 PVA 纤维体积分数为 1.0% 时达到最大值。考虑到所分析的参数，似乎 0.8% 的 PVA 纤维含量为 GPC 的机械性能提供了最佳增强。GPC 的拉伸和弯曲强度、峰值载荷、临界有效裂纹长度、断裂韧性和断裂能也有类似的先增加后减小的趋势，PVA 纤维显着改善了这些趋势。它们在 PVA 纤维含量为 0.8% 时达到最大值，但拉伸强度在 PVA 纤维体积分数为 1.0% 时达到最大值。考虑到所分析的参数，似乎 0.8% 的 PVA 纤维含量为 GPC 的机械性能提供了最佳增强。