Adding Glass Fibers to 3D Printable Mortar: Effects on Printability and Material Anisotropy

Abstract

Adding fibers is an effective way to enhance the printability and mechanical performance of 3D printable cementitious materials. Glass fibers are commonly used owing to their sound mechanical properties, high durability and affordable price. However, there is still a lack of systematic and in-depth research on the effects of adding glass fibers to cementitious materials. In this study, a series of 3D printable mortars with varying glass fiber content and water/cement (W/C) ratio were produced to evaluate their printability, flexural strength and compressive strength. The results showed that decreasing the W/C ratio generally has positive effects on printability and mechanical performance, whereas increasing the glass fiber content from 0% to 1% would substantially improve the extrudability, dimensional stability and buildability; increase the flexural strength by up to 82%; but decrease the compressive strength by up to 35%. Such large differences in the effects of glass fibers on the flexural and compressive strengths indicate significant material anisotropy. In fact, comparison of the strength results of printed specimens to those of un-printed specimens reveals that the printing process could increase the flexural strength by 98% but decrease the compressive strength by 47%.