Electrical and Thermal Properties of Wollastonitebased Inorganic Phosphate Cement Modified with Fibres and Recycled Rubber Aggregates

Abstract

The use of fibres and recycled rubber aggregates to improve the fracture properties of wollastonite-based inorganic phosphate cement would have corresponding effects on the functional properties of the material. In this research, cement composites were designed to incorporate rubber aggregates (i.e. 7.5-17.5 wt%), 1.5% volume fibre contents (i.e. macro polypropylene, amorphous metallic and carbon fibres), and a hybrid blend of both inert materials into the cement matrix. The electrical resistivity of the developed cement composites was measured using the Gamry device while their thermal conductivity was determined based on the guarded hot plate steady state method. It was found that the electrical resistivity of wollastonite-based inorganic phosphate cement increased with increasing curing age at room temperature. The incorporation of rubber aggregates into the cement matrix caused a significant increase and decrease in the electrical resistivity and thermal conductivity respectively, of cementitious composites formed. Meanwhile, as expected, the conductive fibres lowered the electrical resistivity and simultaneously increased the thermal conductivity of the inorganic cement. However, the polypropylene fibres increased both the electrical and thermal properties. Therefore, inert additives which have insulating properties (rubber aggregates and polypropylene fibre) favoured the production of cement composites with improved energy savings in buildings while the conductive (amorphous metallic and carbon) fibres can contribute to the material's smart potential.