Flexural Characterization of Concrete Beams Reinforced with 3D-Printed Formworks

Abstract

3D printing has been on the rise in recent times and the civil engineering industry has adopted this technology due to its various advantages. However, printing is largely restricted to concrete members while the reinforcement is introduced manually. The current work looks at the possibility of using 3D printed thermoplastics as formwork and reinforcement for concrete beams. Three different polymeric materials, namely PETG, PLA, and TPU were utilized in this research to fabricate formwork-like reinforcement for 150×150×500 mm concrete beams. The reinforcements were 3D-printed using a fused deposition modelling (FDM) printer in the shape of a formwork to serve as moulds and external reinforcement. The reinforcing formwork geometry was designed with trapezoidal corrugations to ensure strong bonding with the concrete. The beams were tested in four-point bending configuration, and their flexural behaviour was characterized and compared with plain and steel reinforced concrete (RC) reference beams. Results indicate that all 3D printed beams reached a load capacity of around 30 kN. The post-peak behaviour of these beams was dependent on the type of polymer used. The PLA and TPU reinforced beams exhibit large post-peak deflection however their load carrying capacity was compromised, while the PETG exhibited a strain hardening behaviour but with much lower deflections. Overall, the results indicate that 3D-printed thermoplastics are a promising economical alternative to the conventional steel reinforcement.