Promoting the mechanical features and thermal endurance of OPC - Pumice composites using functionalized multi-walled carbon nanotubes grafted with nano- silica

Abstract The negative environmental damage, exhaustion of resources, and vast energy consumption due to Portland cement (OPC) manufacturing have urged the adoption of supplementary cementitious materials (SCMs) in the form of a partial replacement of cement. The primary objective of this study is to assess the suitability of using pumice powder as a partial substitute for cement to reduce the carbon footprint and mitigate the economic impact of OPC production. Different OPC-pumice pastes were created by replacing OPC with 0%, 15%, and 20% of pumice powder by mass. To enhance the mechanical properties of the prepared pastes under various conditions, minor amounts (0.05, 0.1, and 0.2%) of a functionalized multi-walled carbon nanotubes and silica nanoparticles (MWCNTs/SN) composite were employed. (MWCNTs/SN) composite was prepared in the laboratory using a simple sol–gel method. The mechanical strength, physicochemical characteristics, and thermal stability at various elevated temperatures for different hardened pastes were investigated. Differential thermogravimetric analysis (TG/DTG), X-ray diffraction, and scanning electron microscope imaging proved the formation of many strength-giving phases like ill-crystalline and/or amorphous CSH, CASH, and CAH. The data obtained revealed that the perfect MWCNTs/SN dose is 0.20% by mass of the blend, and nominated OPC-20% Pumice-0.2 MWCNTs/SN composite to be the best choice among all investigated composites for use in construction that is exposed to elevated temperatures.