Mechanical Performance Optimization in Spray-Based Three-Dimensional-Printed Mortar Using Carbon Fiber

Abstract

From the perspective of the features of effective vertical and overhanging construction, the spray-based three-dimensional (S-3D) mortar printing technology has promoted the application of 3D printing in construction fields. Carbon fibers were used to optimize the mechanical performance of S-3D printed mortar. The effects of carbon fiber volume (0%, 0.5%, 1.0%, 1.5%, and 2.0%) and length (3 and 5 mm) on the working properties, printing accuracy, mechanical properties, and microstructural properties of the S-3D printed mortar were studied comprehensively. The test results showed that the S-3D printed mortar with the 1.5 vol% and 3 mm length carbon fiber (L3-V1.5 specimen) showed optimal printing accuracy in the single-layer and accumulative thickness tests. The S-3D printed L3-V1.5 mortar had the maximum flexural strength, which increased by 53.06% and 39.96% at 7 and 28 days, respectively, more than those of its cast counterparts. In addition, the S-3D printing process enhanced the interlayer bonding strength, and the ultimate interlayer splitting strength of the S-3D printed L3-V1.5 mortar increased by 2.16% and 3.33% at 7 and 28 days, respectively, more than those of the cast mortar without carbon fibers. The S-3D printing process improved the carbon fiber alignment and compactness and, thus, the mechanical properties of the S-3D printed mortar.