Structural strain and crack monitoring based on the fluorescence response of graphene quantum dots

Graphene quantum dots (GQDs), a novel nanomaterial, offer new avenues for structural health monitoring owing to the remarkable fluorescence response. In this study, the GQDs-epoxy resin composites were fabricated and applied to structural surface. Tests including tension, compression, bending, and fatigue were conducted to explore the fluorescence response of composites to structural strain and cracks. Results show that composites exhibited a heightened fluorescence sensitivity to structural strain. During the tensile tests of coated steel specimens, the fluorescence intensity of composites exhibited positive and negative correlation responses with increasing strain. Whereas in the compression test of coated concrete specimens, solely increased fluorescence intensity with rising strain was observed. Composites demonstrated excellent crack characterization on concrete and steel structures, whether penetrating or developing cracks. The fluorescence response of composites to cracks was based on the fluorescence