Understanding the role of graphene oxide nanoribbons–functionalized carbon nanotubes–graphene oxide (GNFG) complex in enhancing the fire resistance of cementitious composites

Abstract

• The effect of GNFG on the fire resistance of cementitious composites was tested. • GNFG had better thermal stability than CNTs at high temperatures. • GNFG presented excellent dispersion and promoted the hydration of cement clinkers within the cement paste. • GNFG better preserves the microstructure and mechanical strength of cement paste at high temperatures. In this study, the enhancement effect of synthesized graphene oxide nanoribbons–functionalized carbon nanotubes–graphene oxide (GNFG) complex on the fire resistance of cementitious composites was investigated by comparing it with two traditional nano-reinforcements, carbon nanotubes (CNTs) and graphene oxide (GO). Ordinary Portland cement (OPC) paste reinforced with GNFG, CNTs, and GO at 0.05 wt% were heated to a target temperature of 200, 400, 600, and 800 °C, and the changes in mass loss, bulk density, surface morphology, and mechanical strength were compared with unreinforced OPC paste. The transformation of the microstructure and variation in the hydration products were also analyzed. GNFG exhibited excellent dispersion in the aqueous solution and good thermal stability at high temperatures. Furthermore, it promoted the hydration of anhydrous cement clinkers to produce a denser microstructure and limit the deterioration of the microstructure and mechanical properties of the cement paste at high temperatures. These results suggest that GNFG can play a crucial role as a novel nano-reinforcing agent to improve the mechanical properties and fire resistance of cementitious materials.