Graphene oxide-coated fly ash for high performance and low-carbon cementitious composites

Abstract

Graphene oxide (GO) opens a new pathway for reducing carbon footprint in the construction industry and fabricating high-strength cementitious composites. However, due to the dispersion limitation, the application of GO in practical engineering has not been widely accepted. Hence, we evaluated the potential of the GO-fly ash hybrid as additives in cement under a coating method to assist the dispersion of the GO nanosheets. The results demonstrated that the GO could be successfully coated on the surface of the fly ash particles with good dispersion and strong connection via the proposed coating method. Besides, the coating method allowed more GO nanosheets to concentrate in the interfacial transition zone (ITZ) between fly ash and cement particles, making GO application more economical. The coated GO could then generate nucleation effects to promote the hydration process and provide pore-infilling effects to decrease the ITZ width (about 12.5%) and the crack ratio in ITZ (over 10%). Compared with the plain cement pastes, the workability, mechanical strength, and impermeability of the GO-coated fly ash modified cementitious slurry can be significantly reinforced up to 21.6%, 38.4% and 106.4%, respectively. The enhancement rate is further improved by about 7.1–58.5% compared with the traditional ultrasonic dispersion method. We expect the proposed innovative coating method would provide a good perspective of the future application of high-performance, cost-effective and environmentally friendly cementitious composites.

Keywords

• Cementitious composites
• Nano-modification
• Coating
• Graphene oxide
• Interfacial transition zone