Low-cost flash graphene from carbon black to reinforce cementitious composites for carbon footprint reduction

Abstract

With the merits of high quality, cost-effectiveness, and high yield efficiency, flash Joule heating (FJH) emerges as an efficient means for mass production of flash graphene (FG). It creates prerequisites for the large-scale application of graphene in reinforcing cementitious composites, thus opening innovative possibilities for curbing carbon emissions and fostering the sustainable evolution of cementitious composites. In this study, two types of FGs, including high-purity FG (FG-G) and conductive FG (FG-D), are successfully synthesized via FJH process using carbon black as the carbon source. FG-G features a low ID/IG of 0.52, and exhibits higher graphitization and structural orderliness with fewer defects compared to the FG-D. The addition of 0.25 wt% FG-D increases the compressive strength, flexural strength, and flexural ultimate strain of cementitious composites by 16.48 MPa/16.8%, 1.43 MPa/37.2%, and nearly 2600 με/550%, respectively. The microstructure characterization results reveal that FG reduces the matrix defects, enhances both the matrix microstructure and calcium silicate hydrate gel nanostructure, which is advantageous for matrix refinement, inhibition of microcrack aggregation and propagation, and load transfer efficiency. Its disorderly stacked turbine structure also contributes to robust interface bonding and friction with cement matrix, thus facilitating the strengthening and toughening of cementitious composites. This study introduces a potential avenue to develop widely applicable and versatile silicon-based cementitious composites with high performance and low CO2 emission by using small carbon-based graphene as reinforcement.