矿物掺合料对3D打印水泥基材料力学各向异性的影响

为探究矿物掺合料在3D打印混凝土中的作用机理，研究粉煤灰(FA)、矿粉(S)、硅灰(SF)单掺和复掺对3D打印水泥基材料抗压强度、抗折强度的影响.结果表明：单掺时，打印组和模筑组力学性能的变化规律基本保持一致，粉煤灰和矿粉会降低混凝土的抗压强度和抗折强度，而硅灰则会提高混凝土的力学性能.复掺时，材料力学性能大小顺序为：S+SF>基准组>FA+SF>FA+S.此外，3D打印混凝土的抗压强度无明显各向异性，而抗折强度有明显的各向异性.打印组在x方向的抗折强度比y、z方向低25%～40%,在x、y、z方向的抗折强度比筑模组低10%～30%.

Effect of mineral admixtures on mechanical anisotropy of 3D printed cement-based materials

In order to explore the anisotropy of mechanical properties of 3D printing concrete mixed with mineral admixtures, this paper studies the influence of fly ash (FA), mineral powder (S), silica fume (SF) single and compound admixtures on the compressive strength and flexural strength of 3D printing cement-based materials. The results show that when mineral admixtures are added, the mechanical properties of the printing group and the molding group are basically the same. Fly ash and mineral powder will reduce the compressive strength and flexural strength of concrete, while silica fume improves the mechanical properties of concrete. When mineral admixture is mixed, the order of mechanical properties is: S + SF > reference group > FA + SF > FA + s. In addition, the compressive strength of 3D printed concrete has no obvious anisotropy, but the flexural strength has obvious anisotropy. The flexural strength in the X direction is 25-40% lower than that in the Y and Z directions, and the flexural strength in the X, y and Z directions is 10% - 30% lower than that in the building module.