涂层对速凝3D打印水泥砂浆力学性能的影响

3D打印砂浆普遍存在层间界面粘结较弱、抗折强度较低的问题,而膨胀水泥浆涂层涂覆于砂浆表面可产生表层压应力,进而提升其抗折强度,作为界面剂涂覆于层间可同时增强其界面粘结强度。本文通过将硫铝酸盐水泥与膨胀剂混合而成的涂层涂覆于速凝3D打印砂浆的表面与层间,研究了该涂层对不掺纤维及掺0.5%(体积分数)玄武岩纤维3D打印砂浆试件力学性能的影响规律。结果表明,涂覆层间涂层对无纤维与掺纤维速凝3D打印砂浆的层间界面粘结强度提升率分别为21.4%、12.2%,同时对其抗压强度也有一定提升作用。仅涂覆表面涂层与仅涂覆层间涂层对3D打印砂浆的抗折强度提升效果相当;同时涂覆表面及层间涂层对3D打印砂浆的抗折强度提升效果最显著,与无纤维、掺纤维的无涂层试件相比,提升率最高分别可达44.2%、23.2%。涂层对于无纤维3D打印试件层间粘结强度及抗折强度的提升效果优于掺纤维试件。

Effect of Coating on Mechanical Properties of Rapid Setting 3 D Printing Cement Mortar

3D printing mortar generally has the problems of weak interlayer interface bonding and low flexural strength. The expansion cement slurry coated on the surface of mortar can produce surface compressive stress and then improve its flexural strength. As an interface agent, coating between layers can simultaneously enhance the interfacial bond strength. In this paper, the coating composed of sulphoaluminate cement and expansive agent was coated on the surface and interlayer of the 3D printing mortar, and the effect of the coating on the mechanical properties of the 3D printing mortar specimens without fiber and with 0.5% (volume fraction) basalt fiber was studied. The experimental results show that the interlayer coating improves the interlayer interfacial bond strength of fiber-free and fiber-doped rapid setting 3D printing mortar by 21.4% and 12.2%, respectively. At the same time, it also improves the compressive strength. The effect of coating only surface on the flexural strength of the 3D printing mortar is similar to that of coating only between layers. At the same time, surface coating and interlayer coating have the most obvious improvement effect on the flexural strength of the 3D printing mortar. Compared with the fiber-free and fiber-doped non-coating specimens, the highest improvement rates are 44.2% and 23.2%, respectively. The effect of coating on the interlayer interfacial bond strength and flexural strength of fiber-free 3D printing specimens is better than that of fiber-doped specimens.