Fabrication And Properties Of1-3Orthotropic Polymer/Cement Based Piezoelectric Composite

Cement-based piezoelectric composites which offered good piezoelectric property andgood combination with concrete have gained widely attention. However, due to the transverseisotropy of the piezoelectric ceramics, the common cement-based piezoelectric compositesmade by cutting-casting technique have isotropic characteristic, they receive stress wave inthe plane with the same sensitivity, thus, they cannot be used to effectively detect stress wavetransmitting in a specific direction.In this paper, PZT-5, polymer, sulphoaluminate cement and DAD-91E conducting resinwere used to prepare orthotropic piezoelectric composite by cutting-casting andarranging-casting technique. The piezoelectric property and orthotropic characteristic werestudied, the results show that, the piezoelectric strain constant of1-3orthotropic piezoelectriccomposite is much larger than piezoelectric and1-3piezoelectric composite; the signalvoltage received by piezoelectric ceramic and1-3piezoelectric composite in the orthogonaldirection are nearly identical while the voltages of1-3orthotropic piezoelectric composite arequite different, the value in the0°direction is double that in the90°direction. It demonstratesthat PZT-51and1-3piezoelectric composite show isotropic while1-3orthotropicpiezoelectric composite offers an obvious orthotropic characteristic.The influence factor of1-3orthotropic polymer/cement piezoelectric composite werestudied, the influence of the properties of orthotropic piezoelectric composites were studied aswell. The results show that, the piezoelectric strain constant of1-3orthotropic piezoelectriccomposite increase with the increasing cement mass fraction, the orthotropic piezoelectriccomposites show orthotropic characteristic with different cement mass fraction; thepiezoelectric strain constant of1-3orthotropic piezoelectric composite increase with theincreasing PZT volume fraction, the orthotropic piezoelectric composites show orthotropiccharacteristic with different PZT volume fractions; the piezoelectric strain constant of1-3orthotropic piezoelectric composite increase with the increasing length-width ratio, theorthotropic piezoelectric composites show orthotropic characteristic when the length-widthratio is greater than2; the piezoelectric strain constant of1-3orthotropic piezoelectriccomposite has no change with the increasing thickness, the orthotropic piezoelectric composites show orthotropic characteristic with different thickness; the piezoelectric strainconstant of1-3orthotropic piezoelectric composite decrease with the increasing electrodewidth, the orthotropic piezoelectric composites show orthotropic characteristic with differentelectrode width; the piezoelectric strain constant of1-3orthotropic piezoelectric compositeincrease with the increasing electrode numbers, the orthotropic piezoelectric composites showorthotropic characteristic when the electrode number is greater than2The response rule in the plane and the signal attenuation of1-3orthotropic piezoelectriccomposite were studied. The results show that, the signal amplitude and signal voltagereceived by the piezoelectric ceramic and1-3piezoelectric composite change little from0°to360°while that of1-3orthotropic piezoelectric composite distribute as “cosine curve” withincreasing angles from0°to360°. The signal amplitude and signal voltage received byorthotropic piezoelectric composite decrease exponentially with the increasing distance. Thefarthest distance orthotropic piezoelectric composite can test is1200mm.1-3orthotropicpiezoelectric composite can receive much less signal amplitude on the concrete piece than theceramic title and aluminum plate, this is due to the rough surface and complex structure ofconcrete piece.The orthotropic piezoelectric sensor was developed by using1-3orthotropicpiezoelectric composite as sensing element. The polymer, cement and tungsten powder wereused as matching layer, the polymer and cement were used as backing layer, silver paste wasused for shielding. The properties of orthotropic piezoelectric sensor were studied, the resultsshow that, orthotropic piezoelectric sensor show obvious orthotropic characteristic, it has highsensitivity and wide bandwidth. The orthotropic piezoelectric sensors were used for linearlocation and planar location on the concrete; the results show that, it is accurate with smallerrors.