Comparative effects of sterically stabilized functionalized carbon nanotubes and graphene oxide as reinforcing agent on physico-mechanical properties and electrical resistivity of cement nanocomposites

The study presents the comparison of enhanced mechanical properties of cement nanocomposites (CNCs) incorporating polycarboxylate superplasticizer (PCE-SP) modified graphene oxide and functionalized carbon nanotubes (SP@GO and SP@FCNT). FCNT and GO are stable in aqueous medium but agglomerates in cement solution due to presence of alkaline cement pore solution. So, here an attempt has been made to sterically stabilize GO and FCNT via SP and further their use as reinforcing material is accessed. The extent of stabilization of GO and FCNT by two types of SP in aqueous solution was monitored with the help of UV-Visible spectroscopy. The results have shown that incorporation of 0.02% SP@GO by wt of cement produces the maximum enhancement in compressive strength by 23.2% while utilization of 0.04% SP@GO produces improvement in tensile strength by 38.5%. On the contrary, 0.08 wt% of SP@FCNT improved compressive strength by 16.5% while 0.04 wt% enhances tensile strength by 35.8% with respect to the control sample. In addition to microstructural and crystallization observations, the trends in the physico-mechanical properties and enhanced degree of hydration of calcium silicates as compared to control sample have also been supported by the electrical resistivity values. Moreover, incorporation of SP modified nanomaterials was advantageous for pore structure refinement: the total porosity reduced by 25% and 31% for 0.02% SP@GO-CNCs and 0.08% SP@FCNT-CNCs respectively, as compared to control sample. (C) 2019 Elsevier Ltd. All rights reserved.