Bioinspired design of architected cement-polymer composites

Recent advances in the design of structural composites often mimic natural microstructures. Specifically, the structure of abalone nacre with its high stiffness, tensile strength, and toughness is a source of inspiration from the process of evolution. The inspiration from nacre can lead to design of a new class of architected structural materials with superb mechanical properties. This work presents a combined experimental and computational study on a set of bioinspired architected composites created using a cement mortar cast with brick-and-mortar and auxetic polymer phases. The impact of this unit-cell polymer phase on the flexural and compressive strengths, resilience, and toughness is thoroughly studied as a function of architected geometry. All mechanical properties of the architected composite specimens are found to be greater than those of control samples due to prevention of localized deformation and failure, resulting in higher strength. The architected composites showed more layer shear sliding during fracture, whereas the control samples showed more diagonal shear failure. After initial cracking, the architected composites gradually deformed plastically due to interlocking elements and achieved high stresses and strains before failure. Results also show that composites with the architected polymer phase outperform control samples with equal volume fraction of a randomly oriented polymer fiber phase. Extensive computational studies of the proposed unit cells are also performed and the results suggest that the orientation of cells during loading is critical to achieve maximum performance of a cementitious composite. The implications of these results are immense for future development of high performing construction materials.