Effect of MnO2 nanofibres on the properties of geopolymers fabricated from waste clay

This study focuses on fabrication of geopolymers reinforced with chemically synthesised MnO2 nanofibres, as alternatives to traditional cement-based materials. MnO2 nanofibres were investigated by X-ray diffraction technique, transmission electron microscope, and particle size analyser. Different geopolymer batches were prepared using Feeder’s waste-clay and alkali activator after curing at 70°C. These geopolymers were reinforced with 0.1, 0.3, and 0.5 wt.% MnO2 nanofibres. The mineralogical composition and microstructure of prepared geopolymers were investigated by X-ray diffraction and scanning electron microscope, respectively. The physical properties were determined according to the Archimedes rule, while the compressive strength was measured by the suitable testing machine. The results showed that MnO2 nanofibres were successfully synthesised by the proposed hydrothermal method. Moreover, the synthesised MnO2 nanofibres were successfully utilised for reinforcement of geopolymers. The addition of fibres up to 0.3 wt.% has a significant effect on the physical properties, microstructure, and compressive strength of prepared geopolymer, while the addition of 0.1% or 0.5% changed the properties. The geopolymer sample that included 0.3 wt.% MnO2 fibres exhibited the lowest porosity value (28.47%) and highest compressive strength (28 MPa) among the tested geopolymers. These interesting properties make them applicable for many structural and building applications.