Effect of graphene quantum dots on mechanical properties and microstructure of serpentine concrete

In order to explore the feasibility of using graphene quantum dots (GQDs) as admixtures to improve the properties of serpentine concrete, effects of GQDs dosage on strength, crystal water loss rate, and microstructure of serpentine concrete were investigated at 25, 150, 300, 450, and 600℃. The results show that strength of serpentine concrete at room temperature (25℃) is enhanced with the increase in the dosage of GQDs, and the best enhancement is achieved when the dosage is 0.12wt%, and its 7 days and 28 days compressive strength and 28 days splitting tensile strength are increased by 26.4%, 20.9%, and 27.7%, respectively, compared with the baseline group. The addition of 0.12wt% GQDs reduces the crystal water loss rate of serpentine concrete by 1.8%~20.0%, and increases the compressive strength and splitting tensile strength by 18.0%~34.0% and 29.4%~39.8%, respectively, as compared to serpentine concrete without GQDs during the entire heating period. Microscopic tests show that high temperature environment promotes the hydration of serpentine concrete, as well as GQDs possess better thermal conductivity and nano-filling properties, which together significantly improve the micro-density of serpentine concrete, and the micro-density is highest at 300℃.