Mechanical and Shrinkage Properties of Cement Mortar Modified with Nano-graphene Oxide and Polymer
摘要
To address the issues of high brittleness and significant shrinkage of cement-based materials, the synergistic effects of nano-graphene oxide (GO) and ethylene-vinyl acetate copolymer (EVA) on the mechanical properties and shrinkage behavior of cement mortar were systematically investigated through individual and hybrid incorporation. Individual systems (GO: 0.02wt%, 0.04wt%, 0.06wt%; EVA: 3wt%, 5wt%, 7wt%) and hybrid systems were designed. The 7-day and 28-day flexural strength, compressive strength, and drying shrinkage rate were tested, while thermogravimetric analysis (TG), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM) were employed to characterize the microstructure. The experimental results indicate that, in individual systems, the G4 specimen (0.04wt% GO) exhibits 23.9% and 19.7% enhancements in 28-day flexural and compressive strengths, respectively, compared to the control specimen (PC). The E5 specimen (5wt% EVA) shows an 8.2% improvement in flexural strength. For the hybrid E5G4 specimen (5wt% EVA and 0.04wt% GO), the 28-day flexural and compressive strengths are increased by 30.6% and 25.4%, respectively, relative to PC, with a limited 32.2% rise in drying shrinkage. Microstructural analyses reveal that the lamellar structure of GO promots the densification of C-S-H gel through physical filling and nucleation effects, while EVA forms continuous polymer films to inhibit crack propagation, thereby alleviating shrinkage. This study demonstrates that the hybrid incorporation of GO and EVA synergistically optimizes the mechanical performance of cement-based materials via nano-reinforcement and polymer toughening mechanisms. These findings provide a theoretical basis for the design of high-performance cementitious composites.