Nanoengineering of cement using graphite platelets to refine inherent microstructural defects

Abstract

We use surface-modified graphite nanoplatelets (GNPs) to engineer cement materials at the nanoscale to effectively tailor their macroscale crucial mechanical properties suitable for harsh conditions. Concerning long-term public health and global warming, nanoengineering of cement as a primary barrier for providing zonal isolation by sealing in areas requiring very low risk of serious accidents becomes imperative. Cement inherently possesses microstructural defects, such as, pores/voids and microcracks, which can jeopardize its sealing functionality under large confining in-situ stresses. Here, we develop a chemical methodology for the surface treatment of GNPs, enabling us to enhance chemical and physio-mechanical properties of the produced cement nanocomposite. This surface modification not only changes the hydrophobicity of nanoparticles to hydrophilicity and provides a uniform dispersion of nanoplatelets in aqueous media but also results in the formation of a strong bonding at the GNP/matrix interfaces. The innovative nanoengineered cement composite shows extraordinarily enhancement in the compressive strength, flexural strength, Young's modulus, and the ductility up to 317%, 209%, 255% and 131%, respectively, as compared to the neat cement without using any sort of vibrations during curing. We utilize 3D X-ray computed tomography (CT) in conjunction with the optical microscopy (OM) to visualize the quality of nanoparticles' dispersion. Moreover, scanning electron microscopy (SEM) is used to discern the formation of strong bonding at the GNP/cement matrix interfaces, pore/void refinement and crack bridging.