Cement-based Piezoelectric Composites Research Articles

Influence of cement matrix on properties of 1–3–2 connectivity cement-based piezoelectric composite

In order to develop cement-based piezoelectric intelligent composites suitable for concrete structural health monitoring, 1–3–2 type piezoelectric composites were fabricated by using piezoelectric ceramic as the functional component and epoxy resin and different kinds of cement as the matrix. The properties of the composites were studied. The results show that, compared with pure piezoelectric ceramic, the relative dielectric factor ε33of the composite decreased while the dielectric loss tan δ33increased. The planar electromechanical coupling coefficient Kp, mechanical quality factor Qmand acoustic impedance Z of all the composites decreased, while the thickness electromechanical coupling coefficient Ktincreased. The composite with ordinary Portland cement matrix had the largest values of ε33, tan δ33, Ktand d33(piezoelectric strain factor).

Study on the microstructure of cement-based piezoelectric ceramic composites

In this paper, a study is presented on the microstructure of a cement-based PZT (Lead Zirconate Titanate) piezoelectric ceramic composite. A mechanism is proposed for chemical bonding between piezoelectric ceramic particles and cement material in the composite. The microstructure of the composite, as well as chemical bonding at the ceramic–cement interface is investigated using XRD, IR and XPS. Experimental results indicate that Ti–O in the ceramic particles links to Si–O in the cement paste via bridging oxygen, forming a Ti–O⋯Si–O bonding. And the change of chemical environment takes place for all of Ti, Si, Ca and Zr for cement-based piezoelectric ceramic composites. One prominent result pertaining to chemical reactions at the interface between ceramic particles and cement paste shows that Ti diffuses into the cement paste via Ti–O⋯Si–O bonding.

Fabrication of 1-3 Cement-Based Piezoelectric Ultrasonic Sensors for NDE Applications

This paper described fabrication and comparison of embedded ultrasonic sensors for NDE applications. A 1-3 cement-based piezoelectric composite was used as the sensing element of the ultrasonic sensor. As a front matching layer between test material and piezoelectric materials, cement/epoxy resin was selected. In order to make the backing materials for sensors had enough acoustic attenuation performance, the backing material of sensors doped with tungsten powder. When the mass ratio of tungsten/cement backing was two and the thickness of cement/epoxy resin front-face matching was 3mm, the 1-3 cement-based piezoelectric ultrasonic sensor showed a significant enhancement in both relative pulse-echo sensitivity and-6dB bandwidth. These promising results suggested the great potential for developing high-performance ultrasonic sensors using the 1-3 cement-based piezoelectric composite.

Piezoelectric properties of cement based/PVDF/PZT composites

New and novel cement-based piezoelectric composites were fabricated using lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF) and Portland cement (PC). Dielectric constant (ε33), piezoelectric charge coefficient (d33) and piezoelectric voltage coefficient (g33) of the PZT–PVDF–PC composites with 50vol% PZT and 1–20vol% PVDF content were investigated. The results indicated that PVDF as a third phase was found to enhance piezoelectric properties where piezoelectric charge coefficient (d33) and piezoelectric voltage coefficient (g33) increased to 24pC/N and 25.7×10−3Vm/N respectively when PVDF was added at 5 vol%. Moreover, a significant reduction in the poling time was found when PVDF was incorporated in the 0–3 composites.

Research on a 0–3 cement-based piezoelectric sensor with excellent mechanical–electrical response and good durability

In this study, a novel cement-based piezoelectric sensor was prepared with 0–3 cement-based piezoelectric composites as the sensing element and a mixture consisting of epoxy resin and cement as the encapsulation part, and its mechanical–electrical response measurement was carried out by dynamic load. To realize effective load transmission from the structural material to the sensing element, and to better evaluate and improve the sensor durability, the optimum encapsulation system and sensing element location were explored, and the durability of the cement-based piezoelectric sensor under complicated conditions was studied in detail. Results indicated that the sensor possessed excellent linear performance, with the regression confidence exceeding 0.99 in a large range of 0.31–2.34 MPa, when the ratio of cement to epoxy resin was 3:1 and the sensing element was put in a position near the underside of the encapsulation material. The phase shift between the output voltage and input load was nearly zero and the sensor could respond to pulse load quickly. Environmental conditions including fatigue load and water had a negligible effect on the linearity and sensitivity (slope of fitting line) of the sensor, and in the intended temperature range of 0−40 °C the sensor showed good linearity, almost independent of temperature; nevertheless, the output voltage increased with increasing temperature and the sensitivity reached 1811 mV MPa−1 at 40 °C. Generally, the sensor prepared in this research had excellent mechanical–electrical response and good durability.

Effect of aged binder on piezoelectric properties of cement-based piezoelectric composites

Age-dependent piezoelectric properties of cement piezoelectric composites containing cement-based binder and 50 vol. % PZT piezoelectric inclusions are conducted. The effect of binder with 10 to 50 % cement replaced by slag and fly ash is investigated. Specimens are polarized by 1.5 kV/mm for 30 min when the curing time reaches 7, 28 and 56 days, respectively. Experimental values are measured daily till 120 days after the polarization. Prior to polarization, dielectric loss needs to be less than 0.73 to guarantee the feasibility of polarization. Piezoelectric properties including d33, g33 and ɛr are age-dependent unless the age is higher than 60 days after the polarization. The electromechanical coupling coefficient κt is independent of the ages. The curing time shows less efficient to piezoelectric properties while hydration reaction is completed. 20 vol. % cement replaced by slag or fly ash provides optimum d33 and g33. Compared with slag replacement, fly ash replacement can diminish ɛr, but increase κt. In addition, a modified equation to calculate the dielectric constant of PZT/cement composites is also proposed.

Concrete Damage Detection Based on Embedded Acoustic Emission Sensors

A new kind of embedded acoustic emission (AE) sensor has been developed and it was made up of 1-3 cement-based piezoelectric composites. Compared with those sensors which were traditionally affixed to concrete structures, the embedded AE sensors could minimize the leakage of AE hits and improve the accuracy of data acquisition. The AE thresholds of the sensors are 45dB and they can perceive the position of source and crack extending areas in concrete. Because of the low operation cost, the admirable compatibility with concrete and the excellent durability, the sensors could be widely used in the monitoring of civil structure.

Investigations on Morphology and Domain Configurations in 0–3 Lead Magnesium Niobate Titanate–Portland Cement Composites by SEM and PFM

Lead magnesium niobate titanate (PMNT) and Portland cement (PC) composite were fabricated as a new cement-based piezoelectric composite. Scanning Electron Microscope and Piezoresponse Force Microscope were used to investigate the morphology and domain configurations at the interfacial zone of PMNT-PC composites. Angular PMNT ceramic grains were found to bind well with the cement matrix and PMNT grains can be seen to disperse randomly in the cement matrix. Moreover, the angular shape PMNT particle contributes to better mechanical interlocking with the cement paste due to the angular aggregate having rough surface appearing to provide better mechanical interlocking with the cement paste.

Effect of Pozzolanic Materials and Poling Field on Electromechanical Coupling Coefficient of Cement-Based Piezoelectric Composites

Electromechanical coupling coefficient of cement-based piezoelectric composites affected by pozzolanic materials and poling field are investigated. Specimens, through a pressure approach, are manufactured by combining PZT powders and cement-based binder with the same volume fraction. Pozzolanic materials including fly ash, slag and silica fume replace 20% cement in the binder. Three poling fields are considered to induce piezoelectricity of 0-3 cement-based composites. Results show that electromechanical coupling coefficients do not have many fluctuations in terms of material ages for any cement-pozzolanic piezoelectric composites. With the same volumetric substitutes of pozzolanic materials, the electromechanical coupling coefficient with pozzolanic materials except fly ash is lower than that with plain cement, especially for silica fume having a 7.9% decrease. Raising poling field can increase electromechanical coupling coefficients. Polarization of cement-based piezoelectric composites containing silica fume in low poling fields such as 0.5kV/mm and 1kV/mm is not easy to complete.

A study on polarization properties of the carbon black modified 0-3 cement-based piezoelectric composites

A carbon black modified 0–3 cement-based piezoelectric composite was fabricated with piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O•0.47PbTiO3•0.45PbZrO3], sulphoaluminate cement and carbon black by compressing technique. The influences of poling conditions on the piezoelectric and dielectric properties of the composites were investigated. The results show that the higher poling electric field, the longer poling time and the higher poling temperature, the composites have the higher piezoelectric strain factor d33, piezoelectric voltage factor g33, dielectric constant εr and dielectric loss tanδ. At the same time, the carbon black modified composites are polarized more easily than the unmodified composites, and have better piezoelectric and dielectric properties. Meanwhile, the optimum poling conditions were obtained, and the optimum poling field E, poling time t and poling temperature T were 4 kV/mm, 20 min and 80 °C.

Effect of Poling Temperature on the Barium Ferrite Modified 0-3 Cement-Based Piezoelectric Composites

A barium ferrite modified 0–3 cement-based piezoelectric composite was fabricated with piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O•0.47PbTiO3•0.45PbZrO3], sulphoaluminate cement and barium ferrite by compressing technique. It is well known that in the process of making piezoelectric composites，polarization is very critical, which is the process of domain structure's motion and development in a piezoelectric composites. Without the polarization, the composites will have no piezoelectric properties. So the influences of poling temperature on the piezoelectric and dielectric properties, electromechanical coupling property and acoustic impedance were investigated. And the poling temperature were selected at 30°C、50°C and 80°C. The results showed that the optimum poling temperature were 80°C.

Dynamic analysis of sandwich cement-based piezoelectric composites

Theoretical analysis of a sandwich cement-based piezoelectric composite is presented based on the theory of piezo-elasticity. The steady-state responses of two kinds of this composite under different loading cases are obtained by the use of displacement method. The effects of piezoelectric phases on the performance of this kind of devices are simulated and discussed. The solutions are compared with both the numerical and experimental results, and good agreements are found. Sandwich cement-based piezoelectric composites have great application potential in civil structure health monitoring. The results obtained in this paper are beneficial to the design of this kind of smart devices.

Effects of Polarization on the Strontium Ferrite Modified 0-3 Cement-Based Piezoelectric Composite

Strontium ferrite modified 0-3 cement-based piezoelectric composites were produced with piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O•0.47PbTiO3•0.45PbZrO3], sulphoaluminate cement and strontium ferrite by compressing technique, and the effects of poling conditions on the piezoelectric and dielectric properties were investigated. In order to contrast, a unmodified 0-3 cement-based piezoelectric composite was fabricated. The results show that the higher the poling electric field, the longer the poling time and the higher the poling temperature, the composites have the higher piezoelectric strain factor d33, piezoelectric voltage factor g33, dielectric constant εr and dielectric loss tanδ， and the strontium ferrite modified composites are polarized more easily, and have better properties than the unmodified composites. In the meantime, the optimum poling conditions were obtained, and the optimum poling field E, poling time t and poling temperature T were 5 kV/mm, 20 min and 80 °C.

High piezoelectricity 0–3 cement-based piezoelectric composites

0–3 cement-based piezoelectric composites were prepared with Portland cement as matrix, lead zirconate titanate (abbreviation PZT) as functional phase and powder with high dielectric constant and high specific surface area as enhanced phase. The composites were fabricated with compacted method and the compressive strength was 96MPa. Results indicated that, with 1.5kV/mm polarization voltage and steam curing, the 24h piezoelectric strain constant d33 was 32.4pC/N when the contents of PZT and enhanced phase were 60vol.% and 20wt.%, respectively; d33 exceeded 70pC/N after curing at room temperature and dry atmosphere for 38days; gradually, it reached a constant value 99.0pC/N after 90days. This exhibited superior piezoelectric properties.

Effect of cement matrix and composite thickness on properties of 2-2 type cement-based piezoelectric composites

In this study, 2-2 type cement-based piezoelectric composites were fabricated by dice-and-fill technique. The effects of cement matrix and composite thickness on electrical and acoustic properties of the composite were analyzed. The results show that all the 2-2 type cement-based piezoelectric composites using different kinds of cement as matrix have superior piezoelectric and electromechanical properties. Cement matrix has little influence on the acoustic impedance of the composites, which fluctuates between 13.68 and 15.84 M rayl. With decreasing composite thickness, the piezoelectric strain factor d33, the dielectric factor ερ, and dielectric loss tan δ of the composites decrease, while the piezoelectric voltage factor g33, the thickness electromechanical coupling coefficient Kt, and the mechanical quality factor Qm increase. The acoustic impedance of the composites fluctuates around 14 M rayl with increasing the composite thickness, which is obviously less than that of the pure piezoelectric ceramic. Therefore, 2-2 type cement-based piezoelectric sensors suitable for civil engineering structure can be easily tailored by adjusting the composite thickness.

Electrical Response of Cement-Based Piezoelectric Ceramic Composites under Mechanical Loadings

Electrical responses of cement-based piezoelectric ceramic composites under mechanical loadings are studied. A simple high order model is presented to explain the nonlinear phenomena, which is found in the electrical response of the composites under large mechanical loadings. For general situation, this nonlinear piezoelectric effect is quite small, and the composite is suitable for dynamic mechanical sensor as holding high static stability. The experimental results are consistent with the relationship quite well. The study shows that cement-based piezoelectric composite is suitable for potential application as dynamic mechanical sensor with excellent dynamic response and high static stability.

Dielectric, ferroelectric and piezoelectric properties of 0-3 barium titanate–Portland cement composites

In this work, barium titanate (BT) and cement composites of 0-3 connectivity were produced with BT concentrations of 30%, 50% and 70% by volume using the mixing and pressing method. The dielectric constant (er) and the dielectric loss (tan δ) at room temperature and at various frequencies (0.1–20 kHz) of the ferroelectric BT-Portland cement composites with different BT concentrations were investigated. The results show that the dielectric constant of BT-PC composites was found to increase as BT concentration increases, and that the highest value for er—of 436—was obtained for a BT concentration of 70%. In addition, the dielectric loss tangent decreased with increasing BT concentration. Moreover, several mathematical models were used; the experimental values of the dielectric constants are closest to those calculated from the cube model. The 0-3 cement-based piezoelectric composites show typical ferroelectric hysteresis loops at room temperature. The instantaneous remnant polarization (Pir), at an applied external electrical field (E0) of 20 kV/cm (90 Hz) of 70% barium titanate composite, was found to have a value ≈3.42 μC/cm2. Furthermore, the piezoelectric coefficient (d33) was also found to increase as BT concentration increases, as expected. The highest value for d33 was 16 pC/N for 70% BT composite.

Exact Analysis of 0-3 Cement-based Piezoelectric Composites

Exact static and dynamic analysis of 0-3 cement-based piezoelectric composites is presented based on the theory of piezoelasticity. Displacement method is used and the solutions of four different kinds of piezoelectric composites under different loading cases are obtained. The effects of volume fraction of piezoelectric powder and piezoelectric parameters on the performance of this kind of devices are simulated and discussed. The solutions are compared with both the numerical and experimental results, and good agreements are found. The results obtained in this article are beneficial to the design of this kind of smart devices.

Influence of Base Thickness on Performance of 1-3-2 Piezoelectric Composite

Sulphoaluminate cement and Lead Niobium-Magnesium Zirconate Titanate ceramic [P(MN)]ZT were used as matrix and functional phase respectively to fabricate 1-3-2 cement-based piezoelectric composites by dice and filling technique. The influences of base thickness on piezoelectric properties, electromechanical properties and acoustic impedance properties of the composites were discussed. The results show that as the base thickness increases, the piezoelectric stain factor d33 increases gradually, while the piezoelectric voltage factor g33 decreases. The planar electromechanical coupling coefficient Kp exhibits the trend of decrease, while the thickness electromechanical coupling coefficient Kt and acoustic impedance show the increasing trend. The mechanical quality factor Qm reaches the minimum (1.49) when base thickness is 2.00 mm. The results reveal that the 1-3-2 piezoelectric composite will be suitable for application by changing the base thickness.

Static analysis of 2-2 cement-based piezoelectric composites

Exact static analysis of 2-2 cement-based piezoelectric composites is presented based on the theory of piezo-elasticity in this paper. Displacement method was used, and the solutions of four different kinds of piezoelectric composites under load were obtained. The effects of polarization direction of piezoelectric layers and material parameters on the solutions are discussed. The relationship between the blocking force and the applied voltage for the actuators was obtained. The solutions were compared with both numerical and experimental results, and good agreement was found.