3D printing reinforced concrete structures

This study aims to investigate a 3D printing method to directly incorporate continuous reinforcement into concrete structures. The ability to design and produce complex structures with optimized topographical configuration can be used to reduce potential material waste while maintaining the required structural strength. Furthermore, the ability to actively incorporate reinforcement into printed members substantially reduces potential labor requirements and eliminates the need to set up formwork. The study began its initial approach with a manual extrusion process containing reinforcement to observe the necessary constraints required to achieve a printing system with this functionality. The second stage of development was designing a preliminary 3D printer with an auger-based extrusion system using a dual-entrance nozzle with the capacity to extrude concrete containing shaped reinforcement. The third phase consisted of controlled testing to simulate the impacts of extrusion rate and elapsed time on the final bond capacity of cured, printed specimens. A 3D printing platform with a three-axis printing bed was developed with an embedded printing sequence to synchronize the extrusion of concrete and the insertion of the reinforcement. Various combinations of concrete mixes and types of reinforcement were investigated to produce self-sustaining, printed reinforced concrete members. The preliminary results have shown that the quality of printed reinforced specimens decreases as the extrusion speeds increase. The current results do not indicate any significant impacts on bond capacity by varying extrusion rates and elapsed times”--Abstract, page iii