粉煤灰掺量对PVA-ECC应变硬化性能的影响

Effects of Fly Ash Content on Strain Hardening Properties of PVA-ECC

粉煤灰与水泥反应产生的水化硅酸钙凝胶可以改善骨料与水泥间的界面结构,由此提升聚乙烯醇纤维增强工程水泥基复合材料(PVA-ECC)的韧性.为了确定PVA-ECC的最佳粉煤灰掺量范围并建立其获得高拉伸应变的评价指标,在保证不同配合比PVA-ECC良好流动性的前提下,应用拉伸试验研究粉煤灰掺量对PVA-ECC应变硬化性能的影响,并应用光学扫描研究试件断口处的破坏特征.提出"拔出型""断裂型""滑移硬化型"3种不同纤维破坏模式下PVA-ECC的拉伸应力指数建议值.研究结果表明:粉煤灰掺量在45%~65%时,PVA-ECC的抗拉性能随粉煤灰掺量增大而提高;粉煤灰掺量在60%~65%时,PVA-ECC的抗拉性能最好.

The calcium silicate hydrate gel produced by the reaction of fly ash and cement can improve the interface structure between aggregate and cement,thus improving the toughness of polyvinyl alcohol fiber reinforced engineered cementitious composites(PVA-ECC).To determine the optimal fly ash content range of PVA-ECC and establish its evaluation index for obtaining high tensile strain,the influence of fly ash content on the strain hardening performance of PVA-ECC was studied by tensile test under the premise of ensuring the good fluidity of PVA-ECC with different mix ratios,and the failure characteristics at the fracture of specimens were studied by optical scanning.Three kinds of different fiber damage modes of PVA-ECC index of tensile stress value such as"Pull-out type""Fracture type"and"Slip-hardening type"were established.Results show that when the fly ash content is 45%-65%,the tensile properties of PVA-ECC increase with the increase of the fly ash content.When the fly ash content is 60%-65%,the tensile property of PVA-ECC is the best.