Properties of CNTs-modified lead-free BCTS ceramic–Portland fly ash cement composites

Abstract

Fly ash (FA) is widely used as a supplementary cementitious material in the production of Portland cement concrete. The effect of addition of carbon nanotubes (CNTs) and FA on the properties of barium calcium stannate titanate (BCTS) ceramic–Portland FA cement composites was investigated. These composites have potential for use as sensors and transducers in the monitoring of structural health in concrete structures containing FA. CNTs were found to have filled the pores of the composites. All composites showed good compatibility with the concrete mix. The dielectric constant and electrical conductivity of composites were in the range 200–257 and 1.04 × 10–6 to 1.66 × 10−6 S/m, respectively. The presence of FA in composites increased the piezoelectric voltage coefficient (g33). Adding CNTs increased the piezoelectric charge coefficient (d33), thickness electromechanical coupling coefficient (Kt), and also g33 but decreased mechanical quality factor (Qm), which is related to good for the receiving sensor and transducer application. CNTs can improve the properties of these composites and composite with FA content at 10 vol.%, and CNTs at 1 vol.% exhibited the highest compressive strength and piezoelectric values (d33 = 44 pC/N, g33 = 20.21×10–3 V m/N, and Kt = 18.9%), along with higher g33 values, than pure BCTS ceramic.