Enhancing interlayer bond strength and flexural performance in 3D concrete printing with SHCC bonding agents

Abstract

3D concrete printing (3DCP) faces challenges in weak interlayer and steel reinforcement integration. Existing methods to address these two challenges have limitations in automatic operation and/or limited mechanical enhancement. This study investigates the use of strain-hardening cementitious composites (SHCC) as interfacial bonding agents to simultaneously enhance the interlayer bond strength and flexural performance of 3D printed structures. Three SHCC mixtures with different rheological properties were designed by the adjustment of the viscosity modifying agent (VMA) dosage, and they were used as the interlayer bonding agents, followed by evaluating the interlayer bond strength via splitting tensile test. SHCC-concrete beams, featuring various configurations of SHCC layers, were fabricated and tested via four-point bending to evaluate the flexural per-formance. The results indicate a remarkable increase of 79.58% in interlayer bond strength with the incorporation of SHCC as the bonding agents. In the SHCC-concrete beams, the specimen with an optimal SHCC-layer configuration exhibits a ductile flexural hardening behavior. The flexural strength and deflection increase by 25.53% and 182%, respectively, compared to that of beams without SHCC bonding agents. The findings reveal that the newly developed printing scheme has great potential to simultaneously address the weak interlayer and reinforcement integration problems in 3DCP.