喷墨3D打印纤维增强水泥基材料性能研究

Properties of Fiber-Reinforced Cementitious Materials by Binder Jetting 3D Printing

针对喷墨3D打印水泥基材料的脆性问题,本文提出一种在3D打印水泥粉末中添加纤维的增韧方法。研究纤维在粉末中的分散性,优选纤维种类及长度,通过优化打印工艺提高粉末铺展性能,分析纤维掺量对打印性能和力学性能的影响。结果表明,6 mm以下的纤维在粉末中分散性较好,随纤维长度增加,纤维分散性变差;随纤维掺量的增加,铺展性能和粉床密度下降,提高辊轴速度可有效改善材料的铺展质量。粘结剂受毛细作用在粉末中沿纤维扩散,试件沿辊轴铺展方向的精度最差。弯曲荷载下,破坏试件中玄武岩纤维以拔出破坏为主,而PVA纤维以纤维拉断为主,展现出更好的抗弯性能;相较于未掺纤维的打印试件,1.5%体积掺量的PVA纤维将试件的抗折强度提高63.5%,达到13.6 MPa。

For the brittleness of cementitious materials by binder jetting 3D printing,a toughening method by adding fiber in 3D printing cement powder was proposed in this paper.The dispersion of fibers in powder was investigated and the optimal types and lengths of fibers was selected.Spreadability of powder was improved by optimizing the printing process,effect of fiber content on printing properties and mechanical properties of printed specimens was studied.The results show that fibers with lengths less than 6 mm show better dispersion within the powder;as the length of the fibers increase,the dispersion within the powder becomes worse.Spreadability of powder and powder bed density decrease as fiber contents increasing,and the spreading quality of the material can be effectively improved by increasing the roller speed.Fiber increases the diffusion of binder in powder,and the accuracy of the specimen in the roller spreading direction is the worst.Basalt fiber of the broken specimen is mainly pulled out,while PVA fiber is mainly stretched,thus PVA fiber shows better flexural resistance.The addition of 1.5%PVA fiber resulted in a significant increase in the bending strength of the printed specimen,with an improvement of 63.5%,reaching a value of 13.6 MPa.