Metakaolin/carbon black geopolymer with enhanced electrical properties

Abstract

Alkali-activated binders represent a promising material for composites with self-sensing properties both for their lower environmental impact and ability to transfer the electric charge through ionic mobility. Metakaolin geopolymers with carbon black conductive admixture up to 4% were produced to test their electrical properties, mechanical properties and microstructure. Electrical capacitance, resistance and relative permittivity were determined via impedance spectroscopy analysis. Notable enhancement of all mentioned electrical parameters was registered from 2% carbon black content, especially at lower frequency range. Another carbon black addition was rather unreasonable due to only slight improvement in electrical properties but significant drop of compressive strength and unfavourable changes in pore volume and binder microstructure determined by mercury intrusion porosimetry and electron microscope.