Influence of functionalized carbon nanotubes on the mechanical properties of cementitious materials: Insights from molecular to coarse-grained modeling

Carbon-based one-dimensional nanomaterials, like carbon nanotubes (CNTs), are regarded as excellent options for developing high-performance gelling materials. The mechanical improvement achieved by CNT-reinforced gels is comparable to that of standard cement slurry, likely due to the interactions between the nanomaterials and the products formed during cement hydration. This study aimed to deepen the understanding of how functionalized CNTs influence the mechanical properties of gelled materials. To achieve this, molecular models of CNT-modified cementitious materials with various functional groups were constructed to investigate the impact of these functional groups on improving interfacial strength. On this basis, we further construct the corresponding coarse-grained model by combining the large regular Monte Carlo method and find that the polar functional groups have a strong attraction and a wide range of influence on the particles, which promotes the formation of larger clusters in the system and shows higher mechanical properties. The study hopes to provide molecular and coarse-grained scale insights for future modification applications of carbon nanomaterials in cement concrete. • Nanoscale and mesoscale models of functionalized CNT/C-S-H were built. • Mechanism of enhanced mechanical properties in C-S-H gel by functionalized CNTs was uncovered. • Carboxyl, hydroxyl, and amino groups on CNTs boost bonding with C-S-H gel. • Functionalized CNTs increase adsorption sites for C-S-H nanoparticles.