Harnessing Path Optimization to Enhance the Strength of Three-Dimensional (3D) Printed Concrete

Abstract

The path-dependent strength of three-dimensional printed concrete (3DPC) hinders further engineering application. Printing path optimization is a feasible solution to improve the strength of 3DPC. Here, the mix ratio of 3DPC was studied to print standard concrete specimens with different printing paths using our customized concrete 3D printer, which features fully sealed extrusion and ultrathin nozzles. These paths include crosswise, vertical, arched, and diagonal patterns. Their flexural and compressive strengths were tested. In order to verify the tested results and expose the mechanism of strength enhancement, digital image correlation (DIC) was used to capture the dynamic gradual fracture in the flexural tests. Also, the meso- and microstructures of the 3D-printed concrete specimens were pictured. The results reported here show that arched-path concrete has 30% more flexural strength than others because it makes better use of filament-wise strength. The findings here provide a pathway to improve the strength of 3D-printed concrete by path optimization, boosting 3DPC’s extensive application in civil engineering.