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Influence of water–cement ratio on the properties of 2–2 cement based piezoelectric composite
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Materials Letters 61 (2007) 5217 – 5219 www.elsevier.com/locate/matlet
Influence of water–cement ratio on the properties of 2–2 cement based piezoelectric composite Huang Shifeng, Xu Dongyu, Chang Jun, Ye Zhengmao, Cheng Xin ⁎ School of Materials Science and Engineering, University of Jinan, Jinan 250022, China Received 14 January 2007; accepted 6 April 2007 Available online 19 April 2007
Abstract Composites with 2–2 connectivity were fabricated from plates of “PMN” ceramic embedded in a sulphoaluminate cement matrix by a cut-filling process. The influences of the water–cement ratio in the matrix on the properties of the composite were analyzed. The results show that when the water–cement ratio is less than 0.4, the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase smoothly. When the water–cement ratio is larger than 0.4, d33 and g33 increase obviously with increasing the water–cement ratio. This is attributed to a more effective contact between the active and matrix phases. d33 = 322 pc N− 1 and g33 = 20.9 mV mN− 1 at a water–cement ratio of 0.45. The planar electromechanical coupling coefficient Kp of the composite is nearly independent of the water–cement ratio. With increasing the water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease. © 2007 Elsevier B.V. All rights reserved. Keywords: 2–2 cement based piezoelectric composite; Water–cement ratio; Piezoelectric properties; Electromechanical coupling coefficient
1. Introduction The health monitoring and active-vibration control of structures is of increasing importance in civil engineering fields [1]. The intelligent materials commonly used are often those well used in other fields. These include optical fibres, piezoelectric ceramics and piezopolymers etc. However, the most important structural material in civil engineering is concrete, a kind of solid colloid with many pores. During solidifying process, the effect of hydration, changes in external temperature such as freeze and thaw, moisture and dryness, or heating and cooling can lead to temperature gradient. These lead to an unsymmetrical volume change in the concrete which results in the incompatibility, such as the acoustic impedance matching, temperature coefficient and shrinkage and creep characteristics of concrete, interface bond etc., between intelligent materials suitable for other fields and concrete [2–5]. Therefore, traditional intelligent materials are not suitable for applications in civil engineering fields.
In order to explore intelligent materials suitable for civil engineering, 0–3 cement based piezoelectric composites have been fabricated by Zongjin et al. [5]. The results showed that cement based piezoelectric composite has superior compatibility with concrete. A 0–3 cement based piezoelectric composite using sulphoaluminate cement with characteristic early and high strength as the matrix was first fabricated by our group [6,7]. It was shown that this composite has good electromechanical properties, that is, the voltage has a direct relationship with the force acting on the composite. Although some results of significance have been obtained for cement based piezoelectric composites, many problems remain to be solved. In this paper, a 2–2 sulphoaluminate cement based piezoelectric composite was fabricated and the influence of the water–cement ratio in the matrix phase on the properties of the composite was studied. 2. Experimental procedures 2.1. Sample preparation
⁎ Corresponding author. E-mail address: [email protected] (C. Xin). 0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2007.04.053
A 2–2 cement based piezoelectric composite was fabricated by a cut-filling technique using sulphoaluminate cement and PMN
5218
H. Shifeng et al. / Materials Letters 61 (2007) 5217–5219
ceramic as raw materials. Initially, the piezoelectric ceramic was cut using J5060-1 cutter (Shanghai Wireless Machine Corporation, China) in the parallel direction with polarization axis of the piezoelectric ceramic. The spacing of the ceramic plates is 1 mm, and the thickness for every ceramic plate is also 1 mm. After cut, the ceramic plates were washed. Then the samples were put into the mould for casting cement with continuously vibrating. The water– cement ratio (by weight) is 0.30, 0.35, 0.40, 0.45 and 0.50, respectively. After casting, the fabricated composites were moist-cured (temperature 20 ± 1 °C, relative humidity ≧ 90%) for 7 days. The upper and lower surfaces of the composite were polished until the ceramic plates of the two surfaces appear completely. After polishing, a silver paint was applied on the surfaces of the composites for measurement. The dimensions of all the samples are 15 mm × 7 mm × 1 mm. Fig. 1 shows the surface of the samples and a cross-section of the interface between the ceramic and the cement matrix. The bonding between the ceramic plates and the cement is good. 2.2. Performance test The piezoelectric strain factor d33 of the composite was directly measured using a Model ZJ-3A d33 piezometer (Institute of Acoustics, Chinese Academy of Sciences). Capacitance, resonance frequency, anti-resonance frequency and impedance were measured with an Agilent 4294A Impedance Phase Analyzer. The piezoelectric voltage factor g33, electromechanical coupling coefficient Kp, Kt and mechanical quality factor Qm were calculated, respectively. 3. Results and discussion 3.1. Piezoelectric properties Fig. 2 shows the influence of different water–cement ratio on the piezoelectric properties of the composite. It can be seen that with increasing the water–cement ratio, both the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase. When the water–cement ratio is less than 0.40, d33 and g33 increase smoothly. When the water–cement ratio is larger than 0.40, d33 and g33 increase obviously with increasing water–cement ratio. The reason may be that with increasing water–
Fig. 2. Influence of different water–cement ratio on piezoelectric properties of composite.
cement ratio, the fluidity of the cement paste was improved, which makes the specimens easier to cast and the structure of the composite and the cement is likely more symmetrical. But the content of water cannot be too much, otherwise the whole mechanical properties of the composite decrease, which is not suitable for the practical application of the composite. 3.2. Electromechanical coupling properties The planar and thickness electromechanical coupling coefficient of cement based piezoelectric composite were calculated in this paper. Table 1 shows the electromechanical coupling properties of the cement based piezoelectric composite under different water–cement ratio. Kp can be obtained from Kp ∼ ▵f/fs chart. Kt and Qm can be concluded by the following equations [8]:
Kt2
p fs p fp fs ¼ tan fp 2 fp 2 1
Qm ¼
2pfs RC
ðfp2 fs2 Þ fp2
Where, fs and fp are series and parallel resonance frequency, respectively. C and R are the capacitance and the minimum impedance value. It can be seen from Table 1 that the planar electromechanical coupling coefficient Kp is nearly independent of the water–cement ratio. With the increasing water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease, which indicates that the larger the water–cement ratio is, the higher resolution factor for the cement based piezoelectric composite to be used as the transducer is.
Table 1 Electromechanical coupling properties of composite with different water– cement ratio Properties
Fig. 1. Surface and interface combination of the composite.
Kp/% Kt/% Qm
W–C ratio 0.30
0.35
0.40
0.45
0.50
43.1 45.8 7.6
43.1 53.5 5.3
41.7 56.5 4.7
43.1 57.8 4.9
41.7 58.5 4.1
H. Shifeng et al. / Materials Letters 61 (2007) 5217–5219
4. Conclusions (1) 2–2 cement based piezoelectric composites were fabricated using sulphoaluminate cement as matrix and PMN layers as the active component. (2) When the water–cement ratio is less than 0.40, the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase smoothly. When the water–cement ratio is larger than 0.40, d33 and g33 increase obviously with increasing the water–cement ratio. (3) The planar electromechanical coupling coefficient Kp of the composite is nearly independent of the water–cement ratio. With increasing the water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease. Acknowledgments This work is supported by the National Science Foundation of China (grant no. 50672032, 50502017) and Natural Science Foundation of Shandong Province (grant no. Y2005F08).
5219
References [1] [2] [3] [4] [5] [6]
S. Aizawa, T. Kakizawa, M. Higasino, Smart Mater. Struct. 7 (5) (1998) 617. Dong Zhang, Kure Wu, Zongjin Li, J. Build. Mater. 5 (2) (2002) 141. Dong Biqin, Zongjin Li, Compos. Sci. Technol. 65 (9) (2005) 1363. Z.J. Li, D. Zhang, K.R. Wu, Mater. Struct. 34 (2001) 506. Zongjin Li, Dong Zhang, Kure Wu, J. Am. Ceram. Soc. 85 (2) (2002) 305. Shifeng Huang, Jun Chang, Futian Liu, et al., J. Mater. Sci. 39 (23) (2004) 6975. [7] Xin Cheng, Shifeng Huang, Jun Chang, et al., J Eur Ceram. Soc. 25 (2005) 3223. [8] IEEE Standard on Piezoelectricity [S]. ANSI/IEEE Std. 176-1987. USA: American National Standard. (1987) p.227.
Materials Letters 61 (2007) 5217 – 5219 www.elsevier.com/locate/matlet
Influence of water–cement ratio on the properties of 2–2 cement based piezoelectric composite Huang Shifeng, Xu Dongyu, Chang Jun, Ye Zhengmao, Cheng Xin ⁎ School of Materials Science and Engineering, University of Jinan, Jinan 250022, China Received 14 January 2007; accepted 6 April 2007 Available online 19 April 2007
Abstract Composites with 2–2 connectivity were fabricated from plates of “PMN” ceramic embedded in a sulphoaluminate cement matrix by a cut-filling process. The influences of the water–cement ratio in the matrix on the properties of the composite were analyzed. The results show that when the water–cement ratio is less than 0.4, the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase smoothly. When the water–cement ratio is larger than 0.4, d33 and g33 increase obviously with increasing the water–cement ratio. This is attributed to a more effective contact between the active and matrix phases. d33 = 322 pc N− 1 and g33 = 20.9 mV mN− 1 at a water–cement ratio of 0.45. The planar electromechanical coupling coefficient Kp of the composite is nearly independent of the water–cement ratio. With increasing the water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease. © 2007 Elsevier B.V. All rights reserved. Keywords: 2–2 cement based piezoelectric composite; Water–cement ratio; Piezoelectric properties; Electromechanical coupling coefficient
1. Introduction The health monitoring and active-vibration control of structures is of increasing importance in civil engineering fields [1]. The intelligent materials commonly used are often those well used in other fields. These include optical fibres, piezoelectric ceramics and piezopolymers etc. However, the most important structural material in civil engineering is concrete, a kind of solid colloid with many pores. During solidifying process, the effect of hydration, changes in external temperature such as freeze and thaw, moisture and dryness, or heating and cooling can lead to temperature gradient. These lead to an unsymmetrical volume change in the concrete which results in the incompatibility, such as the acoustic impedance matching, temperature coefficient and shrinkage and creep characteristics of concrete, interface bond etc., between intelligent materials suitable for other fields and concrete [2–5]. Therefore, traditional intelligent materials are not suitable for applications in civil engineering fields.
In order to explore intelligent materials suitable for civil engineering, 0–3 cement based piezoelectric composites have been fabricated by Zongjin et al. [5]. The results showed that cement based piezoelectric composite has superior compatibility with concrete. A 0–3 cement based piezoelectric composite using sulphoaluminate cement with characteristic early and high strength as the matrix was first fabricated by our group [6,7]. It was shown that this composite has good electromechanical properties, that is, the voltage has a direct relationship with the force acting on the composite. Although some results of significance have been obtained for cement based piezoelectric composites, many problems remain to be solved. In this paper, a 2–2 sulphoaluminate cement based piezoelectric composite was fabricated and the influence of the water–cement ratio in the matrix phase on the properties of the composite was studied. 2. Experimental procedures 2.1. Sample preparation
⁎ Corresponding author. E-mail address: [email protected] (C. Xin). 0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2007.04.053
A 2–2 cement based piezoelectric composite was fabricated by a cut-filling technique using sulphoaluminate cement and PMN
5218
H. Shifeng et al. / Materials Letters 61 (2007) 5217–5219
ceramic as raw materials. Initially, the piezoelectric ceramic was cut using J5060-1 cutter (Shanghai Wireless Machine Corporation, China) in the parallel direction with polarization axis of the piezoelectric ceramic. The spacing of the ceramic plates is 1 mm, and the thickness for every ceramic plate is also 1 mm. After cut, the ceramic plates were washed. Then the samples were put into the mould for casting cement with continuously vibrating. The water– cement ratio (by weight) is 0.30, 0.35, 0.40, 0.45 and 0.50, respectively. After casting, the fabricated composites were moist-cured (temperature 20 ± 1 °C, relative humidity ≧ 90%) for 7 days. The upper and lower surfaces of the composite were polished until the ceramic plates of the two surfaces appear completely. After polishing, a silver paint was applied on the surfaces of the composites for measurement. The dimensions of all the samples are 15 mm × 7 mm × 1 mm. Fig. 1 shows the surface of the samples and a cross-section of the interface between the ceramic and the cement matrix. The bonding between the ceramic plates and the cement is good. 2.2. Performance test The piezoelectric strain factor d33 of the composite was directly measured using a Model ZJ-3A d33 piezometer (Institute of Acoustics, Chinese Academy of Sciences). Capacitance, resonance frequency, anti-resonance frequency and impedance were measured with an Agilent 4294A Impedance Phase Analyzer. The piezoelectric voltage factor g33, electromechanical coupling coefficient Kp, Kt and mechanical quality factor Qm were calculated, respectively. 3. Results and discussion 3.1. Piezoelectric properties Fig. 2 shows the influence of different water–cement ratio on the piezoelectric properties of the composite. It can be seen that with increasing the water–cement ratio, both the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase. When the water–cement ratio is less than 0.40, d33 and g33 increase smoothly. When the water–cement ratio is larger than 0.40, d33 and g33 increase obviously with increasing water–cement ratio. The reason may be that with increasing water–
Fig. 2. Influence of different water–cement ratio on piezoelectric properties of composite.
cement ratio, the fluidity of the cement paste was improved, which makes the specimens easier to cast and the structure of the composite and the cement is likely more symmetrical. But the content of water cannot be too much, otherwise the whole mechanical properties of the composite decrease, which is not suitable for the practical application of the composite. 3.2. Electromechanical coupling properties The planar and thickness electromechanical coupling coefficient of cement based piezoelectric composite were calculated in this paper. Table 1 shows the electromechanical coupling properties of the cement based piezoelectric composite under different water–cement ratio. Kp can be obtained from Kp ∼ ▵f/fs chart. Kt and Qm can be concluded by the following equations [8]:
Kt2
p fs p fp fs ¼ tan fp 2 fp 2 1
Qm ¼
2pfs RC
ðfp2 fs2 Þ fp2
Where, fs and fp are series and parallel resonance frequency, respectively. C and R are the capacitance and the minimum impedance value. It can be seen from Table 1 that the planar electromechanical coupling coefficient Kp is nearly independent of the water–cement ratio. With the increasing water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease, which indicates that the larger the water–cement ratio is, the higher resolution factor for the cement based piezoelectric composite to be used as the transducer is.
Table 1 Electromechanical coupling properties of composite with different water– cement ratio Properties
Fig. 1. Surface and interface combination of the composite.
Kp/% Kt/% Qm
W–C ratio 0.30
0.35
0.40
0.45
0.50
43.1 45.8 7.6
43.1 53.5 5.3
41.7 56.5 4.7
43.1 57.8 4.9
41.7 58.5 4.1
H. Shifeng et al. / Materials Letters 61 (2007) 5217–5219
4. Conclusions (1) 2–2 cement based piezoelectric composites were fabricated using sulphoaluminate cement as matrix and PMN layers as the active component. (2) When the water–cement ratio is less than 0.40, the piezoelectric stain factor d33 and piezoelectric voltage factor g33 increase smoothly. When the water–cement ratio is larger than 0.40, d33 and g33 increase obviously with increasing the water–cement ratio. (3) The planar electromechanical coupling coefficient Kp of the composite is nearly independent of the water–cement ratio. With increasing the water–cement ratio, the thickness electromechanical coupling coefficient Kt of the composite increases, while the mechanical quality factor Qm exhibits the trend of decrease. Acknowledgments This work is supported by the National Science Foundation of China (grant no. 50672032, 50502017) and Natural Science Foundation of Shandong Province (grant no. Y2005F08).
5219
References [1] [2] [3] [4] [5] [6]
S. Aizawa, T. Kakizawa, M. Higasino, Smart Mater. Struct. 7 (5) (1998) 617. Dong Zhang, Kure Wu, Zongjin Li, J. Build. Mater. 5 (2) (2002) 141. Dong Biqin, Zongjin Li, Compos. Sci. Technol. 65 (9) (2005) 1363. Z.J. Li, D. Zhang, K.R. Wu, Mater. Struct. 34 (2001) 506. Zongjin Li, Dong Zhang, Kure Wu, J. Am. Ceram. Soc. 85 (2) (2002) 305. Shifeng Huang, Jun Chang, Futian Liu, et al., J. Mater. Sci. 39 (23) (2004) 6975. [7] Xin Cheng, Shifeng Huang, Jun Chang, et al., J Eur Ceram. Soc. 25 (2005) 3223. [8] IEEE Standard on Piezoelectricity [S]. ANSI/IEEE Std. 176-1987. USA: American National Standard. (1987) p.227.