Preventing cement-based materials failure by embedding Fe2O3 nanoparticles

M Laanaiya and A Zaoui, CONSTRUCTION AND BUILDING MATERIALS, 260, 120466 (2020).

DOI: 10.1016/j.conbuildmat.2020.120466

Calcium silicate hydrate (C-S-H), the major component of hydrated cement, is responsible for the main mechanical properties of concrete. The aim of this work is to study the structural and mechanical properties of C-S-H modified by embedding Fe2O3 nanoparticles through molecular dynamics simulations. Nanoparticles with different diameters ranging from 2.1 nm to 3.0 nm were selected to analyze the size effect on interactions between the inserted nanoparticles and C-S-H matrix. Results show that the smallest nanoparticle gives the best adhesion with C-S-H. Furthermore, two insertion modes of nanoparticles inside the C-S-H matrix were compared in order to elucidate how nanoparticles distribution affects the mechanical response of the hybrid composite Fe2O3/C-S-H. The structure with "well-dispersed" nanoparticles exhibits remarkable mechanical performance in both elastic and plastic regimes. Mechanical properties were enhanced with at least 24% increase compared to pure C-S-H. The strength of modified C-S-H with uniformly distributed Fe2O3 nanoparticles is substantially enhanced along the three directions. In the plastic phase, the "group effect" of inserted nanoparticles gives rise to a higher ductility. Finally, the necking phenomenon and structural hardening were both observed in response to tensile loading, indicating a ductile failure mode of Fe2O3-reinforced C-S-H. (C) 2020 Elsevier Ltd. All rights reserved.

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