Engineering cementitious composite with nature-inspired architected polymeric reinforcing elements using additive manufacturing method

Concrete, known for its excellent compression strength, faces challenges in tensile strength, requiring additional steel or polymers reinforcements. Incorporating nature-inspired patterns in reinforced cementitious composites (RC) has shown promise in enhancing mechanical properties by introducing stress distribution and energy absorption mechanisms. Various nature-inspired architectures, inspired by plant stems, Bouligand structures, nacre, and honeycomb structures, exhibit favorable mechanical improvements. However, implementations of natural architectures in RC may need adjustments for specific applications. Additive manufacturing (AM) in concrete elements offers the potential to include intricate and nature-inspired RC designs. While AM provides advantages in rapid and cost-effective construction, reinforcing concrete with steel in this process poses challenges in terms of energy and time constraints. As an alternative, polymers in AM have drawn attention due to their capability to create complex, including nature-inspired, designs in RC construction. However, concerns persist regarding the mechanical properties of additively manufactured polymers compared to conventional counterparts. The current study initially delves into optimizing the mechanical properties of additively manufactured polymers by exploring various printing process parameters. It highlights the potential of AM to introduce sophisticated and nature-inspired architectures at micro-scale including twisted patterns into the reinforcing element, addressing issues such as tensile strength and ductility of polymeric reinforcement. Additionally, the study contributes advanced insights into systematically introducing nature-inspired macro-scale architectural designs in reinforcement layout to develop architected polymeric reinforced cementitious composites (APRCs) with enhanced flexural performance. Macro-scale architectures include investigations of cellular patterns such as hexagonal and sinusoidal architectures, and hollow patterns including single and double tubular architectures in APRC. Furthermore, the work studies the synergic integration of nature-inspired hollow patterns into Mechanics of Materials (MoM)-based reinforcement layout design to further enhance flexural response and develop bio-inspired engineered polymeric reinforced cementitious composite (EPRC). Numerical and experimental methods are used simultaneously for predicting and evaluating the impact of nature-inspired architected reinforcing elements on the mechanical behavior of cementitious composites. Results verify that incorporating twisting nature-inspired micro-architectures (e.g., Bouligand, and Sinusoidal) into reinforcing elements enhances their tensile strength and toughness; consequently, this can improve the flexural properties of RC. It is found that hollow macro-architectures contribute to a higher APRC flexural strength than cellular architectures. Additionally, promising enhancement in EPRC flexural response was observed when nature-inspired hollow patterns were integrated into MoM-based reinforcement layouts. This work shows that developments of APRC and EPRC can lead to promising enhancements in the flexural performance of RC and can be implemented in the design of future advanced civil infrastructure. Indeed, further investigations are required to study the long-term temperature-dependent dimensional and durability performance of APRC and EPRC.