Nacre-mimetic Calcium Silicate Hydrate (C-S-H) Composite with High Strength and Toughness

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