浆体流变性能对超高延性水泥基材料性能的影响

Effect of Rheology on Properties of Ultra-high Ductility Cementitious Composites

浆体的流变性能是影响纤维在水泥基材料中分散性的关键因素,是采用聚乙烯(PE)纤维制备超高延性水泥基材料(Ultra-high ductility cementitious composites, UHDCC)的重要指标。本工作通过调整水胶比和外加剂的掺量调控浆体的流变性能,研究浆体的屈服应力和塑性黏度对UHDCC流动性、拉伸、抗压和断裂性能的影响。结果表明:调整水胶比和外加剂可以调控UHDCC浆体的流变特性,其流变行为符合假塑性流体。浆体塑性黏度在1.91~6.00 Pa·s范围内的UHDCC呈现不同程度的拉伸应变硬化行为;塑性黏度的最佳范围为3.06~4.60 Pa·s,此时纤维在基体中分散更加均匀,因此UHDCC具备更加优异的拉伸性能和断裂韧度,其拉伸应变可以超过10%。

The homogeneous dispersion of fibers determined by the rheological properties of mortar is an essential index for developing ultra-high ductility cementitious composites(UHDCC) with polyethylene(PE)fibers. In this work, the water-binder ratio and content of admixtures were adjusted to control the rheological properties of mortar, and the influence of the yield stress and plastic viscosity of mortar on the flowability, tensile, compressive and fracture properties of UHDCC were studied. The results showed that the rheological properties of UHDCC mortar could be controlled by adjusting water-binder ratio and admixtures, according to the behavior of pseudoplastic fluid. UHDCC with the plastic viscosity of 1.91 Pa·s to 6.00 Pa·s exhibited the tensile strain-hardening behavior with various degrees. The plastic viscosity of mortar controlled within a reasonable range, around 3.06 Pa·s to 4.60 Pa·s, could achieve superior tensile capacity with a tensile strain up to 10% due to a better dispersion of fibers.