Abstract
Cementitious composites generally suffer from low tensile strength, poor toughness, and insufficient durability, which significantly compromise their structural integrity and stability and shorten service life. To address these drawbacks, two-dimensional nanomaterials are innovatively introduced as admixtures for fabricating cementitious composites in this work. Within the composite matrix, hexagonal boron nitride (h-BN) and MXene generate synergistic effects via pore filling, hydration product refinement, microcrack bridging and hydration acceleration, greatly densifying and homogenizing the matrix to comprehensively improve the composite performance. The obtained hybrid specimen containing 0.5 wt% h-BN and 0.5 wt% MXene displays excellent integrated properties over the pristine and single-doped specimens, with tensile strength, compressive strength and impermeability increased by 12.7%, 40.4% and 80.7%, respectively, alongside remarkable improvements in thermal stability and fire resistance. Among single-doped groups, the specimen modified with 1.0 wt% h-BN achieves a 65% improvement in flexural strength, whereas the sample filled with 0.5 wt% MXene delivers a 16% enhancement in compressive strength. Although existing theoretical simulations predict considerable strengthening potential for functionally graded composites reinforced with two-dimensional nanofillers, these quantitative predictions cannot be directly transferred to reactive cementitious systems. This study provides quantitative experimental data on mechanical and durability enhancements originating from synergistic h-BN/MXene modification. It validates the feasibility of employing 2D nanofillers to reinforce cementitious matrices and offers a new pathway for developing next-generation high-performance cementitious composites.