膨润土对3D打印砂浆可打印性能的影响

In order to explore the influence law of bentonite and its content on the printable properties of 3D printing mortar, the fluidity is used to evaluate the extrudability of the mortar, and the height retention rate and penetration resistance are used to evaluate its stackability. In addition, the rheological behavior of the slurry is tested by dynamic and static shear tests, and the influence of bentonite on the printable properties of the mortar is analyzed from the perspective of rheology. The results show that there is a good linear relationship between the fluidity of the printable mortar and the plastic viscosity of the neat paste, and a good logarithmic relationship with the dynamic yield stress; the height retention rate has a good exponential relationship with the static yield stress. On the one hand, bentonite increases the plastic viscosity and dynamic yield stress of the slurry, resulting in a decrease in the extrudability of the mortar. On the other hand, bentonite increases the static yield stress and structure reconstruction rate of the slurry, thereby improving the stackability of the mortar. Therefore, an appropriate amount of bentonite can make the mortar maintain good extrudability and improve the stackability of the mortar. When the content of bentonite is 2%, the ratio of the top and bottom widths of the printed specimen is 0.96.

为探明膨润土及其掺量对3D打印砂浆可打印性能的影响规律,采用流动度评价砂浆的可挤出性,并以高度保留率和贯入阻力评价其可堆叠性。此外,采用动态、静态剪切测试浆体的流变行为,从流变学角度分析膨润土对砂浆可打印性能的影响。结果表明:可打印砂浆流动度与净浆的塑性黏度存在良好的线性关系,与动态屈服应力存在良好的对数关系;高度保留率则与静态屈服应力存在良好的指数关系。一方面,膨润土增大了浆体的塑性黏度与动态屈服应力,从而导致砂浆的可挤出性能降低。另一方面,膨润土提高了浆体静态屈服应力和结构重建速率,从而提高砂浆的可堆叠性能。因此,适宜掺量的膨润土可使砂浆保持良好可挤出性,且改善砂浆的可堆叠性。当膨润土掺量2%时,打印试件顶底宽度比为0.96。