Influence of polymer insertion on the dielectric, piezoelectric and acoustic properties of 1-0-3 polyurethane/cement-based piezo composite

Cement/polyurethane based piezo composite was fabricated with 1-0–3 connectivity. Microstructural analysis shows that polyurethane (PU) acts as a binder, reducing the porosity and improving the matrix adhesion to the piezoelectric phase. Dielectric characterisation shows that PU strongly reduces both the interfacial polarisation process and the ionic mobility in the matrix, thus decreasing the dielectric constant and increasing the values of voltage constant (g33) and electromechanical coupling coefficient (kt). The composite was surface mounted on a porous concrete bar and evaluated as an acoustic emission sensor (AE). The results show that this material is a highly sensitive sensor for AE detection in the frequency range 50–220 kHz.