Mechanical and Photocatalytic Properties of Cement Composites Containing Metal and Oxide Nanoparticles

In this communication, we report cement composites containing Fe₂O₃ (iron oxide), TiO₂ (titanium dioxide), SiO₂ (silicon dioxide) and Cu (copper) nanoparticles added to ordinary portland cement (OPC) in various wt.%. Compressive strength measurements on the OPC-Fe₂O₃, OPC-TiO₂, OPC-SiO₂ and OPC-Cu samples are carried out systematically at the standard curing ages of 3, 7, 14 and 28 days, which show significant improvement in the mechanical strength at the optimum dose (wt.%) of nanoparticles. Highest increase in the compressive strength (33%) and flexural strength (20%) is seen for OPC-Fe₂O₃ (3 wt.% Fe₂O₃) at a curing age of 28 days. Studies on the OPC-TiO₂, OPC-SiO₂ and OPC-Cu composites show improvement in mechanical strength compared to that of reference OPC. Increase in mechanical strength is a result of faster and better cement hydration product (C-S-H gel) caused by the availability of higher active surface area of added nanoparticles. X-ray diffraction studies show the presence of C-S-H gel phase in the oxide-cement composites. Thermal treatment on OPC-Fe₂O₃ composites shows drastic degradation of compressive strength beyond 100 °C due to microcrack formation. Based on the compressive strength with optimum dose, we have carried out smart photocatalytic dye degradation (rhodamine-6G) studies on all the composites. OPC composites ground powder re-dispersed in de-ionized water and ultrasonicated before ultraviolet-visible dye degradation studies. The studies show faster dye degradation for all the composites compared to reference OPC. Highest degradation rate (~ 2.5 time) is obtained with OPC-Fe₂O₃ composite. Our studies show that these multifunctional oxide-cement composites can be used for dye degradation producing cleaner environment without loss of mechanical strength prerequisite for building application.