Graphene Quantum Dots as Nanoadditives in Cement Hydration: Mechanistic Insights into Pore Structure Refinement and Durability Enhancement

High Resolution Image Download MS PowerPoint Slide Graphene quantum dots (GQDs) have emerged as promising nanoscale modifiers for tailoring interfacial processes in cementitious systems; however, their mechanistic role in hydration and pore structure evolution remains insufficiently understood. The effects of dual-form GQDs (liquid and solid) on the structure–property relationships of concrete across multiple strength classes (24–42 MPa) were investigated. The results demonstrated that the incorporation of 0.1% liquid-form GQDs produced the most significant enhancement in concrete performance, achieving up to 32% improvement in 28-day compressive strength, 36% increase in splitting tensile strength, and approximately 18% increase in flexural strength compared with the control mixture. In addition, water absorption and porosity were reduced by approximately 25% and 32%, respectively, while acid resistance was significantly improved under aggressive exposure conditions. BET analysis further shows a substantial reduction (∼43%) in mesopore volume, confirming that GQDs govern pore structure evolution rather than acting solely as fillers. Notably, the dispersion state of GQDs critically influences performance, with liquid-phase GQDs exhibiting superior efficiency compared to their powdered counterparts due to improved interfacial distribution and reduced agglomeration. This study establishes a direct link between GQD-mediated cement chemistry, microstructural densification, and durability performance, providing a mechanistic framework for the design of next-generation nanoengineered cementitious materials for harsh service environments.