Multi-Layered Calcium Silicate Hydrate-Based Composites: A Nacre-Mimetic Design for Ultra-High Toughness.

Area of Science:

• Materials Science
• Civil Engineering
• Nanotechnology

Background:

• Cement-based materials are ubiquitous but limited by low toughness, hindering critical infrastructure applications.
• Calcium silicate hydrate (C-S-H), the main hydration product, dictates cementitious material properties.
• Optimizing C-S-H is a key strategy for enhancing material toughness.

Purpose of the Study:

• To develop a high toughness C-S-H composite using a nacre-mimetic design.
• To investigate the toughening mechanisms and mechanical properties of the novel composite.
• To explore potential applications in advanced functional composite systems.

Main Methods:

• Employed a nacre-mimetic design strategy with inorganic C-S-H 'bricks' and polyvinyl alcohol (PVA) 'mortar'.
• Utilized density functional theory (DFT), molecular dynamics (MD), and finite element method (FEM) simulations.
• Characterized the hierarchical structure and mechanical performance of the composite.

Main Results:

• Achieved a hierarchical soft/hard structure significantly improving mechanical properties.
• Demonstrated 1-2 orders of magnitude enhancement in tensile strength, ductility, and toughness compared to conventional composites.
• Attained ultra-high toughness (20.01±3.64 MJ m⁻³) exceeding nacre by over ten times.

Conclusions:

• The nacre-mimetic C-S-H composite exhibits superior toughness and mechanical properties.
• The study reveals intricate interface and toughening mechanisms through advanced simulations.
• Findings offer a promising pathway for toughening cement-based materials for advanced applications.