| The objectives of this thesis are to develop and apply a new smart composite for the sensing and actuation application of civil engineering. Piezoelectric ceramic powder is incorporated into cement-based composite to achieve the sensing and actuation capability.; The research investigates microstructure, polarization and aging, material properties and performance of cement-based piezoelectric ceramic composites both theoretically and experimentally. A hydrogen bonding is found at the interface of piezoelectric ceramic powder and cement phase by IR (Infrared Ray), XPS (X-ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectroscopy). It largely affects the material properties of composites. A simple first order model is introduced to explain the poling mechanism of composites and the dependency of polarization is discussed using electromechanical coupling coefficient kt. The mechanisms acting on the aging effect is explored in detail.; Dielectrical, piezoelectric and mechanical properties of the cement-based piezoelectric ceramic composites are studied by experiment and theoretical calculation based on modified cube model (n=1) with chemical bonding . A complex circuit model is proposed to explain the unique feature of impedance spectra and the instinct of high-loss of cement-based piezoelectric ceramic composite.; The sensing ability of cement-based piezoelectric ceramic composite has been evaluated by using step wave, sine wave, and random wave. It shows that the output of the composite can reflects the nature and characteristics of mechanical input.; The work in this thesis opens a new direction for the current actuation/sensing technology in civil engineering. The materials and techniques, developed in this work, have a great potential in application of health monitoring of buildings and infrastructures. |
