Steel microfibres in fly ash geopolymer for multifunctional conductive composites

Steel fibres in construction materials not only enhance their mechanical and fracture properties but also increase their capability of electrical conductivity. This feature thus enables the material to obtain advanced multifunctional properties that can be utilized in self-sensing and other smart applications. Fly ash geopolymers with steel microfibres in 5-30% wt. were prepared to assess the influence of the fibres on selected electrical properties of the composite (resistance, capacitance and relative permittivity) with respect to mechanical performance. Microstructure and interfacial bonding of matrix and steel fibres was observed by electron microscopy imaging. Steel fibres caused an improvement in all assessed electrical properties but only above a certain frequency values. Furthermore, steel reinforced samples exhibited increase in both compressive and flexural strength.