High electric permittivity of polymer-modified cement due to the capacitance of the interface between polymer and cement

Wang, Min; Chung, D.D.L.

doi:10.1007/s10853-018-2088-8

Cited by 10 publications

(6 citation statements)

References 56 publications

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“…Thus, the poling of a large concrete structure is not feasible and the elimination of the need for poling is practically important. Partly due to the effect of admixtures on the permittivity [64][65][66], piezoelectric behavior can also be present in some cement-based materials that do not contain a piezoelectric admixture, but contain conductive admixtures such as carbon nanotubes [67]. In a recent report [47] by this research group, capacitance-based stress sensing in cement paste without any admixture requirement was observed and it was noted that the sensing stems from the direct piezoelectric effect of the cement paste.…”

Section: Piezoelectric Cement-based Materialsmentioning

confidence: 96%

Piezoelectricity-based self-sensing of compressive and flexural stress in cement-based materials without admixture requirement and without poling

Shi¹,

Chung²

2018

Smart Mater. Struct.

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The self-sensing of compressive and flexural stress in cement-based materials (without embedded or attached sensors, without admixture requirement and without poling) by capacitance measurement has been demonstrated. The sensing involves two coplanar electrodes in the form of aluminum foil adhered to the cement-based material by using adhesive tape, which also serves as a dielectric film. The normal force associated with compressive or flexural loading is applied to the region between the electrodes. The stress regimes are the low-stress regime (up to 1500 Pa), the medium-stress regime (1500–7400 Pa) and the high-stress regime (7400–65 000 Pa). The lowest compressive/flexural stress demonstrated for effective sensing is 300 Pa. The fractional decrease in capacitance per unit stress is up to 2.2 × 10−6 Pa−1 and tends to decrease as the regime is changed from low to medium and to high-stress. The sensitivity tends to be greater for the compressive stress than flexural stress. However, when the normal stress (relevant to weighing) is considered, the sensitivity is higher for flexural loading than compressive loading. The strain contributes negligibly to the capacitance decrease, though the near-surface deformability of the cement-based material contributes. The change in capacitance upon stress application is attributed to the direct piezoelectric effect. The sensitivity is comparable for cement paste, mortar and concrete. Capacitance-based self-sensing is advantageous over resistance-based self-sensing in terms of the low-stress sensing effectiveness, absence of admixture or aggregate proportion requirements, essential absence of self-sensing effectiveness reduction by the presence of aggregates, wide applicability to existing concrete structures, and ease of applying electrodes.

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Section: Piezoelectric Cement-based Materialsmentioning

confidence: 96%

Piezoelectricity-based self-sensing of compressive and flexural stress in cement-based materials without admixture requirement and without poling

Shi¹,

Chung²

2018

Smart Mater. Struct.

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“…In a similar vein, the permittivity of the cement‐based material after hydration increases with the humidity 10 and with increasing water/cement ratio, 11–14 though the opposite trend of the permittivity decreasing with increasing water/cement ratio has also been reported 15 . The permittivity is also affected by the admixtures, such as latex (styrene butadiene), methylcellulose, silica fume, graphite, and slag, which introduce interfaces and additional phases in the material 16–20 . Interfaces affect the permittivity, whether space charge polarization occurs at the interfaces or not.…”

Section: Introductionmentioning

confidence: 99%

“…Admixtures (e.g., latex, silica fume, graphite, etc.) affect the AC permittivity of cement‐based materials 16–20 . However, the effect of admixtures on the DC polarization characteristics of cement‐based materials has received less attention as previously reported only for silica fume 22 and the combination of carbon fiber and either silica fume or latex 23 .…”

Section: Introductionmentioning

confidence: 99%

“…15 The permittivity is also affected by the admixtures, such as latex (styrene butadiene), methylcellulose, silica fume, graphite, and slag, which introduce interfaces and additional phases in the material. [16][17][18][19][20] Interfaces affect the permittivity, whether space charge polarization occurs at the interfaces or not.…”

Section: Introductionmentioning

confidence: 99%

“…affect the AC permittivity of cement-based materials. [16][17][18][19][20] However, the effect of admixtures on the DC polarization characteristics of cement-based materials has received less attention as previously reported only for silica fume 22 and the combination of carbon fiber and either silica fume or latex. 23 The addition of silica fume decreases the extent of DC polarization, but the effect is small.…”

Section: Introductionmentioning

confidence: 99%

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DC electric polarization of cured cement paste being unexpectedly hindered by free water

Öztürk

Chung

2021

J Am Ceram Soc.

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Electric polarization is basic to the dielectric behavior, which is pertinent to the science and applications of cement‐based materials. This work reports the dynamics of the DC‐current‐induced electric polarization/depolarization of cured cement paste and their dependence on the water/cement ratio. This dependence has not been previously reported for any cement‐based material. The extent of the polarization is unexpectedly found in this work to decrease as the water/cement ratio increases, indicating that the free water hinders the polarization. This hindrance is due to (i) the dominance of ions behind the polarization (as supported by the previously reported increase in permittivity with increasing temperature), and (ii) the polar water molecules partly shielding the ions from the applied electric field. The fraction of ions in the pore solution that participates in the polarization increases with the polarization time and is 4.5 × 10‐14 for 570 s of polarization at a current of 1 μA for water/cement ratio 0.35. Upon increasing the water/cement ratio (0.3–0.4), the polarization rate decreases, the polarization extent at a given polarization time decreases, and the time to reach polarization saturation decreases. The polarization/depolarization rate decreases as the current application progresses because the polarization/depolarization hinders further polarization/depolarization. The degree of this hindrance increases with increasing water/cement ratio. Thus, a higher water/cement ratio is preferred if less polarization is desired as in resistance‐based self‐sensing, whereas a lower water/cement ratio is preferred if more polarization is desired as in capacitance‐based self‐sensing.

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Development, design and applications of structural capacitors

Chung

2018

Applied Energy

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High electric permittivity of polymer-modified cement due to the capacitance of the interface between polymer and cement

Cited by 10 publications

References 56 publications

Piezoelectricity-based self-sensing of compressive and flexural stress in cement-based materials without admixture requirement and without poling

Piezoelectricity-based self-sensing of compressive and flexural stress in cement-based materials without admixture requirement and without poling

DC electric polarization of cured cement paste being unexpectedly hindered by free water

Development, design and applications of structural capacitors

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