AC electrical properties of geopolymers with carbon black admixture

Abstract

Geopolymers as competitors to the cement-based construction materials are intensively studied in the present. Their competitiveness mainly arises from their high strength, favourable development of hydration heat at early age, good chemical resistance and thermal stability. Further qualitative improvement of functional properties can be achieved by adding electrically conductive admixtures. In an appropriate amount (called percolation threshold), mechanical properties remain reasonable and electrical properties become sufficient to ensure evolution of heat by acting of an external power source (self-heating), to detect material damage (self-sensing) or to harvest thermoelectric energy (energy harvesting). In this paper three geopolymers with different dosages of carbon black (CB) admixture (0 wt. %, 4 wt. %, 10 wt. %) were studied by means of LCR bridge AC measurements. It was observed significant difference in electrical behavior of the studied geopolymers. 0 wt. % geopolymer exhibited highly capacitive character, 4 wt. % geopolymer was slightly shifted to resistive behavior and 10 wt. % geopolymer behaved like resistor even to high frequencies with reasonable resistance which indicates its possible self-heating ability.