Inter-layer reinforcement of 3D printed concrete elements

Abstract

Concrete 3D printing is an emerging technology in the construction sector, and it has been undergoing an exponential increase in that field. Nowadays, one of the most challenging subjects in 3D printing is the reinforcing method, particularly at the interface level between printed layers. These interfaces are considered the weakest parts in a printed element, and are the cause of its anisotropic behavior. Therefore, the study at hands first presents a customized 4-point bending test, developed particularly to evaluate the effectiveness of a newly developed inter-layer reinforcing technique. Second, it evaluates the effects and potentials of inserting steel nails or screws across successive layers. The type of reinforcement in terms of surface geometry, as well as the effect of the reinforcement’s number and arrangement over the printed surfaces was extensively assessed. Hence, it was found that inter-layer reinforcement is possible using local reinforcement. Notably, the results demonstrated that the surface geometry of the reinforcing agents greatly influences the quality of the bond generated with printed concrete layers. Precisely, reinforcements having smooth surfaces can be a real advantage to strengthen the interfaces between successive layers if properly distributed and implemented.