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.