The thermal conductivity of the matrix part of alumina – carbon unshaped refractory has been estimated to accurately interpret its thermophysical and thermomechanical behavior. The properties of precalcined composite matrix containing either as-received or surface-modified graphite in equal quantity (20.0 wt%) have been investigated at three different temperatures (110,550,900 °C). The thermal compatibility or degradation of both kinds of carbonaceous matrices had been correlated with respective scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analyses. The monolithic matrices were also subjected to X-ray diffraction (XRD) studies to distinguish between their phase evolution patterns. A synergestic study on an equivalent graphite-free formulation was also carried out. The thermal shock resistance profile of respective castables had been addressed to confirm the superiority of surface-treated graphites. Nanoengineering at graphite surface was conceived by Rietveld analysis of the (004) peak that substantiated the additional influence of calcium aluminate coating on selective clumping and partial exfoliation of graphite sheets. © 2020 Elsevier Ltd and Techna Group S.r.l.