Green synthesis of graphene by flash joule heating for reinforcing low-carbon cement-based composites

Graphene has exceptional mechanical, electrical, and thermal properties, as well as ultra-high specific surface area, which has attracted interest as a potential modifier for reinforcing cement-based composites. However, traditional graphene production methods are often time-consuming, costly, and involve chemical solvents, limiting their widespread application in cementitious materials. This study employed a green and solvent-free flash Joule heating (FJH) technique to rapidly synthesize high-quality, low-defect flash graphene (FG) from inexpensive carbon black, which was subsequently used to produce high-performance cement-based composites. Experimental results indicated that both discharge voltage and discharge duration are critical factors influencing FG quality. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed that FG synthesized at 200 V and 0.5 s exhibits a turbostratic stacking structure with an interlayer spacing (0.343 nm) larger than that of traditional AB-stacked graphene (0.335 nm). Such structural features enhanced its dispersion in the cementitious matrix. Incorporating 0.20 wt% FG significantly enhanced cement hydration and improved the pore structure, resulting in a 161% increase in compressive strength. Life cycle analysis revealed that FG-reinforced cement composites achieved 30% carbon emission reduction and 144% improvement in performance-cost index. This study combines eco-friendly, rapid graphene synthesis with low-carbon cementitious materials, offering a novel approach for efficient utilization of carbon-rich solid waste. It holds significant implications for reducing construction-related carbon emissions and advancing sustainable building materials.