Electrical and Sulfate-Sensing Properties of Alkali-Activated Nanocomposites

Abstract We investigated the formation of the conductive network of carbon nanotubes (CNTs) in alkali-activated nanocomposites for sulfate-sensing applications. The matrix was a one-part blend of fly ash and ground granulated blast-furnace slag, activated by sodium silicate and water. Sodium dodecylbenzenesulfonate was used as the surfactant for dispersion of the CNTs in the aqueous media. The nanocomposites were investigated by a laboratory-developed setup to study the electrical and sensing properties of the alkali-activated material. The electrical properties (i.e., conductivity) were calculated and assessed to discover the percolation threshold of the nanocomposites. Furthermore, the sensing behavior of nanocomposites was studied upon sulfate ( $${\mathrm{SO}}_{4}^{2-}$$ SO 4 2 - ) exposure by introduction of sulfuric acid ( $$({\mathrm{H}}_{2}{\mathrm{SO}}_{4})$$ ( H 2 SO 4 ) ) and magnesium sulfate ( $${\mathrm{MgSO}}_{4}$$ MgSO 4 ). The sensors were able to preliminarily exhibit a signal difference based on the introduced media ( $${\mathrm{H}}_{2}{\mathrm{SO}}_{4} \&\mathrm{ Mg}{\mathrm{SO}}_{4}$$ H 2 SO 4 & Mg SO 4 ), CNT content and $${\mathrm{H}}_{2}{\mathrm{SO}}_{4}$$ H 2 SO 4 volumetric quantity. The results of this research demonstrated a sensing potential of CNT alkali-activated nanocomposites and can be applied in the concrete structural health monitoring.