Aluminum-Induced Interfacial Strengthening in Calcium Silicate Hydrates: Structure, Bonding, and Mechanical Properties
Qi Zheng, Jinyang Jiang, Jin Yu, Xinle Li, Shaofan Li
Abstract
Calcium aluminosilicate hydrate has attracted significant interests, because of its low carbon footprint, while basic questions persist concerning its molecular-level properties. In this work, the material chemistry of C-A-S-H is systematically investigated, and its micro-structure at atomic scale is reexamined based on first-principles modeling and simulation. We find that the cross-link between interlayers is crucial for mechanical strengths, which is responsible for ∼36.2% enhancement of the bulk modulus and ∼10.0% of shear modulus. Anomalous C-A-S-H exhibits zeolitic features with interatomic Al–O–Si bonding. With the reversible structural transformation and other physical incentives, C-A-S-H can be categorized into soft porous crystals. Aluminum substitution induces interfacial strengthening in calcium silicate hydrates by raising tensile and compressive strength by ∼76.1 and ∼16.9%, respectively. Uncovering these reinforcement mechanisms, including the interlayer strengthening, provides theoretical underpinnings for future design for green cement with ultrahigh performance.