Nacre-mimetic calcium silicate hydrate (C–S–H) composite with high strength and toughness

Abstract

Low toughness remains an enduring constraint of cementitious materials. Manipulating calcium silicate hydrate (C–S–H), the “genetic component” of cement, which determines the mechanical properties of cementitious materials, presents an attractive strategy for intrinsic toughening. However, its modulation is constrained by the small-length scale and limited enhancement. Herein, this work proposes an approach to fabricate nacre-mimetic C–S–H bulk composites with brick-mortar microstructures. The composite exhibits an excellent combination of high flexural strength, toughness and impact resistance, with toughness surpassing that of pure C–S–H and cement paste by factors of over 1000, even outperforming natural nacre, reinforced cement-based materials and existing reported C–S–H-based materials. The nacre-mimetic C–S–H composite also exhibits a 20- to 30-fold increase in impact resistance and flexural strength compared with pure C–S–H, respectively. Multi-scale simulations reveal strengthening and toughening mechanisms, including molecular-scale coordination, nano-asperity formation, viscoplastic deformation, and crack deflection across micro- to macro-scales. The developed C–S–H nacre not only achieves remarkably high toughness and broadens the potential for scalable application but also paves the way for designing advanced bioinspired cementitious and silicate-based materials for structural applications.