Piezoelectric composite cements: Towards the development of self-powered and self-diagnostic materials

Piezoresistivity is the most commonly used sensing principle in cement-based smart composites for strainmonitoring applications. Nonetheless, the need for external electric power to conduct electrical resistivity measurements restricts the scalability of this technology, especially when implemented in remote structures. To address this issue, this manuscript thoroughly analyses the piezoelectric properties of cement composites doped with reduced graphene oxide (rGO) and evaluates their potential as self-powered strain sensors. To do so, a comprehensive methodology involving voltammetry measurements, open circuit potential determination, and uniaxial compression testing is developed to determine the piezoelectric coefficients of charge �33 and voltage �33. Furthermore, a novel circuital model for signal processing of the electromechanical response is developed and experimentally validated in terms of time series of output voltage, resistance, and the generated electric power. The developed methodology is applied to laboratory samples manufactured following two different filler dispersion methods. The presented results evidence that samples prepared by ultrasonic cleaner dispersion achieve optimal properties, with a piezoelectric charge coefficient of 1122.28 ± 246.67 pC/N, about 47 times greater than previously reported composites in the literature. Unlike piezoresistive cement-based composites, a remarkable nonlinear correlation between the fractional change in the intrinsic resistance of the material and the applied mechanical strain has been observed. Instead, a considerable linearity (R 2 = 0.96) between the externally applied mechanical strain and the generated (piezoelectric) electric power has been found, which suggests the great potential of the latter for conducting off-the-grid strain monitoring applications

Cement-Based Piezoelectricity Application: A Theoretical Approach

The linear theory of piezoelectricity has widely been used to evaluate the material constants of single crystals and ceramics, but what happens with amorphous structures that exhibit piezoelectric properties such as cement-based? In this chapter, we correlate the theoretical and experimental piezoelectric parameters for small deformations after compressive stress–strain, open circuit potential, and impedance spectroscopy on cement-based. Here, in detail, we introduce the theory of piezoelectricity for large deformations without including a functional for the energy; also, we show two generating equations in terms of a free energy’s function for later it will be reduced to constitutional equations of piezoelectricity for infinitesimal deformations. Finally, here is shown piezoelectric and electrical parameters of gold nanoparticles mixed to cement paste: the axial elasticity parameter Y=323.5±75.3kN/m2, the electroelastic parameter γ=−20.5±6.9mV/kN, and dielectric constant ε=939.6±82.9ε0F/m, which have an interpretation as linear theory parameters sijklD, gkij and εikT discussed in the chapter

Effective medium electrical response model of carbon nanotubes cement-based composites

The electrical properties of carbon nanotubes (CNT) cement-based composites have been modeled in previous works by circuit models or homogenization theories. An alternative approach is the use of an effective medium theory with induced polarization: In this work, a new model based on the generalized effective medium theory of induced polarization (GEMTIP) with cylindrical inclusions is proposed. The presented results and discussion show its applicability to interpret the electrical impedance spectra of cylindrical cement samples doped with multi-walled CNTs (MWCNTs). The MWCNTs were dispersed in different media: one nonionic surfactant, two superplasticizers, a cationic type polycarboxylate ether, and an anionic type naphthalene sulfonate. Particle dispersion and their sizes were analyzed by Ultraviolet–Visible (UV–Vis) spectroscopy, and Scanning Electron Microscopy (SEM) measurements. Two electrode electrical impedance spectra were measured and analyzed by circuital models and the proposed GEMTIP model. The results demonstrate the efficiency of the proposed model in describing the Alternating Current (AC) response of cement/CNT composites irrespective of the dispersant agent used to elaborate the samples.CBUAConsejería de Transformación Económica, Conocimiento, Empresas Universidades de la Junta de Andalucía P18-RT-3128MinCiencias 82779Piezoresistividad en Pasta de Cemento con Adición de Nanopartículas de Oro o Materiales CarbonososUniversidad de GranadaInstituto Colombiano de Crédito Educativo y Estudios Técnicos en el Exterio

Pypiezo-GO: A software tool for processing electromechanical measurements of piezoelectric reduced graphene oxide-cement composites

Self-diagnostic composites have become increasingly popular for structural health monitoring due to their ability to develop load-bearing strain sensors. Piezoelectric cement composites, in particular, represent an emerging area of research with vast potential for developing innovative self-powered or ultra-low power consumption sensors. In this context, this paper presents Pypiezo-GO, a software tool designed for the electromechanical characterization of reduced graphene oxide (rGO)-cement composites. The software tool, developed as an online cloud computing platform, accesses a database organized into DataFrame structures. The database contains the measurements from a set of experiments conducted on rGO-cement samples, including open circuit potential, cyclic voltammetry, and compressive testing. On this basis, Pypiezo-GO allows extracting the electrical properties of the samples, including their capacitance and piezoelectric factors. Furthermore, the platform enables the comparison of experimental time series with numerical predictions from a lumped circuit model implemented in MATLAB/Simulink, which is also included in this contribution. The presented software code is intended to represent a valuable tool for the development of new piezoelectric cement composites for strain self-sensing applications

Method for fabricating self-powered cement sensors based on gold nanoparticles

Nowadays, cement industry researchers are working hard to develop cement sensors based on nanocomposites because they can be used to develop intelligent and sustainable civil structures, self-powered, self-healing, or self-monitoring. In this light, this paper shows a methodology to obtain piezoelectric cement sensors, which produce enough energy not to require an external power source in sensing-strain applications. Mainly, two proposed experimental procedures increased the piezoelectric properties of these cement-based composites: add gold nanoparticles in the proper concentrations and apply a constant electric field during the curing stage. Firstly, the gold nanoparticles were obtained through a pulsed laser ablation system, and their particle size distribution was measured with a particle analyzer Litesizer 500 from Anton Paar, and their morphology was corroborated using a scanning electron microscope. Two concentrations (442 ppm and 658 ppm) of gold nanoparticles were obtained by changing the total ablation time. Next, we fabricated the cement sensors as described by ASTM standards C39-C39M. Hence, the cement was hand mixed with a water-to-cement ratio (w/c) of 0.47 for then poured on cylindrical molds saving the proportions recommended by the ASTM standard; in this stage, the gold nanoparticles were already part of the water ratio. Then, the cement sensors were cured under an external electric field and dried for 24 hours more in an oven to be finally ready for electromechanical characterization. Meanwhile, the electric response in altern current and the piezoelectric behavior were corroborated through electrical impedance spectroscopy and open circuit potential measurements, respectively. The piezoelectric behavior was obtained when a compressive strength was applied to the sensor, and the generated voltage was simultaneously measured. Finally, the electrical and mechanical characterization measurements were processed and analyzed using Python scripts. • The particle size and the families amount of Au NPs are affected by the ablation time. • The correct proportion of Au NPs increases the inherent piezoelectricity of cement paste. • The piezoelectric response can be addressed by coupling electric and mechanical tests

Curva característica de voltaje y corriente de un ADN autoensamblado

This paper shows a research on the transport properties of two-dimen-sional square lattice patterns built from a telomeric DNA sequence. A tight-binding model, and the recursive Green’s function method were used. It is showed that the self-assembled DNA structures based on telomeric DNA strands have current-voltage (I-V) characteristics, with robust plateau structures that favor the scrutiny of DNA-lead, as well as interference effects. An increase of the current, dependent on the distance between the crosses in the self-assembled square lattice structures, is observed, which makes the system eligible for nanoelectronic applications.Este artigo mostra um trabalho no qual se pesquisam numericamente as propriedades de transporte dos padrões de uma rede quadrada bidimen-sional construída a partir de uma sequência de DNA telomérico, por meio de um modelo tight-binding efetivo para a estrutura eletrônica, enquanto a corrente é obtida dentro do âmbito de funções de Green. Mostra-se que as estruturas de DNA autoassembladas baseadas em correntes de DNA teloméricas têm características de voltagem de corrente com uma robusta sequência de etapas que favorecem o controle do DNA com os contatos, bem como os efeitos de interferência. Observam-se variações interessantes do mecanismo de percolação, que dependem da competição entre a longitude de localização e a distância entre os cruzamentos nas estruturas de rede quadrada bidimensional autoensambledas, as quais fazem que o sistema seja elegível para aplicações nano eletrônicas.Este artículo muestra un trabajo en el que se investigan numéricamente las propiedades de transporte de los patrones de una red cuadrada bidimensio-nal construida a partir de una secuencia de ADN telomérico, a través de un modelo tight-binding efectivo para la estructura electrónica, mientras que la corriente se obtiene dentro del marco de funciones de Green. Se muestra que las estructuras de ADN autoensambladas basadas en cadenas de ADN teloméricas tienen características de voltaje de corriente con una robusta secuencia de escalones que favorecen el control del ADN con los contactos, así como los efectos de interferencia. Se observan variaciones interesantes del mecanismo de percolación, que dependen de la competen-cia entre la longitud de localización y la distancia entre los cruces en las estructuras de red cuadrada bidimensional autoensambladas, las cuales hacen que el sistema sea elegible para aplicaciones nanoelectrónicas

Time-Stability Dispersion of MWCNTs for the Improvement of Mechanical Properties of Portland Cement Specimens

This study shows the energy optimization and stabilization in the time of solutions composed of H2O + TX-100 + Multi-Wall Carbon Nanotubes (MWCNTs), used to improve the mechanical properties of Portland cement pastes. For developing this research, sonication energies at 90, 190, 290, 340, 390, 440, 490 and 590 J/g are applied to a colloidal substance (MWCNTs/TX-100 + H2O) with a molarity of 10 mM. Raman spectroscopy analyses showed that, for energies greater than 440 J/g, there are ruptures and fragmentation of the MWCNTs; meanwhile at energies below 390 J/g, better dispersions are obtained. The stability of the dispersion over time was evaluated over 13 weeks using UV-vis spectroscopy and Zeta Potential. With the most relevant data collected, sonication energies of 190, 390 and 490 J/g, at 10 mM were selected at the first and the fourth week of storage to obtain Portland cement specimens. Finally, we found an improvement of the mechanical properties of the samples built with Portland cement and solutions stored for one and four weeks; it can be concluded that the MWCNTs improved the hydration period