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

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.