Mechanisms of carbon black in multifunctional cement matrix: Hydration and microstructure perspectives

Zhang, Qian; Luan, Congqi; Yu, Chongxiu; Huang, Yuguang; Zhou, Zhen

doi:10.1016/j.conbuildmat.2022.128455

Cited by 32 publications

(3 citation statements)

References 46 publications

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“…Among them, the content of C element is the most; this is because yak dung is not burned sufficiently in the muffle furnace, which is mainly found in carbon black. The small size of carbon black in relation to cement particles allows it to be dispersed within the cement matrix during the preparation of cement mortars, where it can fill some of the pores and improve the microstructure of the matrix [ 39 ]. On the other hand, the elements Si, Al and Ca are mainly present in the form of oxides in YDA and can be directly involved in the hydration reactions of cement.…”

Section: Resultsmentioning

confidence: 99%

Synergistic Effect of Yak Dung Fiber and Yak Dung Ash on the Mechanical and Shrinkage Properties of Cement Mortar

Zhu

Li²,

Tian³

et al. 2023

Materials

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The high value use of agricultural and livestock waste resources in the context of a low carbon economy is a challenge that currently plagues many countries. Yak dung, as a waste resource from livestock farming in the plateau, is considered to be a misplaced treasure. In this work, yak dung was processed into yak dung fiber (YDF) and yak dung ash (YDA), respectively, and the microscopic morphology of the YDF and YDA was assessed using scanning electron microscopy (SEM). The elements in the YDA were analyzed by energy dispersive X-ray spectroscopy (EDX). Moreover, cementitious composites were prepared with YDF at 0%, 0.3%, 0.5% and 0.7% and by replacing cement with YDA at 5%, 10% and 15% to assess the workability, mechanical properties and shrinkage properties of cementitious composites containing different YDF types (alkali treated and untreated), contents and different YDA contents. The results showed that alkali-treated YDF and YDA contain a large number of honeycomb structure pores, and the strength of cementitious materials with alkali-treated YDF was higher. The addition of YDF had a negative effect on the fluidity and compressive strength of the cementitious material, but the 0.3% YDF was beneficial in increasing its flexural strength. The compressive strength and flexural strength first increased and then decreased with the increase of YDA content. Both YDF and YDA inhibited the shrinkage of the cement paste, and the shrinkage strain of the cement matrix composites containing 0.3% YDF and 10% YDA was reduced by 51.1% compared to the control group. This work is expected to promote the application of yak dung waste in cementitious materials.

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Section: Resultsmentioning

confidence: 99%

Synergistic Effect of Yak Dung Fiber and Yak Dung Ash on the Mechanical and Shrinkage Properties of Cement Mortar

Zhu

Li²,

Tian³

et al. 2023

Materials

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“…The conductive paths are created by the conductive particles directly in contact with each other as cementitious crystals nucleate during the hydration process and repel SWCNT and nCB to the boundaries. Furthermore, since the distance between the adjacent nanoparticles is diminishing, junctions are formed, enabling electrons to easily pass through this junctions via “hopping” or “tunneling” mechanisms. , The electrical conductivity and the Seebeck coefficient of the organic TE materials are determined by the doping level. Increasing the doping level can lower S while increasing σ.…”

Section: Resultsmentioning

confidence: 99%

Structural Carbon-Enhanced Cementitious Thermoelectric Generators (TEGs): Optimal Energy Filtering and TEG Design for Outstanding Energy Harvesting

Vareli,

Gkaravela,

Polyviou

et al. 2023

ACS Appl. Electron. Mater.

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We report on the development of a cementitious structural thermoelectric generator (TEG), exhibiting a significantly improved power density of 1.2 W/m 2 , via the optimization of the thermoelectric response of individual thermoelements and the TEG assembly. Toward this aim, we combined nano carbon black (nCB) and single-walled carbon nanotubes (SWCNTs) within the cementitious matrix to maximize the carrier-filtering effect for optimal thermoelectric efficiency. The multidimensional carbon nanomaterials self-assembled through electrostatic forces during the dispersion process in aqueous media and formed conductive networks inside the cement matrix at low filler contents. Simultaneously, the additional interfaces between the nCB and the SWCNT nano-reinforcement supported the selective scattering of low-energy carriers. Thus, cementitious thermoelements with significantly enhanced Seebeck coefficient were produced. To our knowledge, the Seebeck, S (+4644.2 μV/K), and power factor, PF (1.51 × 10 4 μW/mK 2 ), values attained in this study are the highest ever reported to date for nanoadditivebased cementitious thermoelectric nanocomposites. The optimal design of the proposed Hybrid TEG device (utilizing thermoelements with only SWCNTs and with SWCNTs/nCB reinforcement) resulted in a decrease of the internal electrical resistance of our cementitious thermoelectric generator, further optimizing its power output, which enabled, under a small ΔΤ of 25 K, the generation of enough power for the autonomous operation of microelectronic devices, like wireless sensors.

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“…The agglomeration of carbon black within the cementitious matrix forms a conductive network in SSM. However, it should be noted that pores tend to appear around the regions with carbon black, as it acts as an inert filler and does not form chemical bonds with the surrounding cementitious matrix (Qian et al 2022). These pores contain air, an insulating medium in dry conditions, and contain water, a conducting medium when moisture is present.…”

Section: Sem Observationmentioning

confidence: 99%

Stress Self-sensitivity of Carbon Black-filled Mortar under Nondestructive Compression and the Effects of Electric Circuit and Specimen Dimensions

Chi,

Hai,

Lan

et al. 2023

ACT

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Cement-based materials with self-sensing capabilities have the potential to be used as compression load cells in various applications. This study aims (i) to clarify the change in resistivity in self-sensing mortar (SSM) under nondestructive compressive stress and the underlying mechanism of this change, (ii) to examine the effects of different conditions such as electric circuit and specimen dimension on this relationship. The study involved SSM specimens containing 7% carbon black powder with various parameters, including excitation voltage, intermediate resistor for the electric circuit, and electrode distance, dimensions of the cube SSM specimen. Additionally, scanning electron microscopy (SEM) observations were performed to investigate the dispersion of carbon black in the cementitious matrix. SEM observations reveal the agglomeration and dispersion of carbon black within the cementitious matrix, creating a conductive network in SSM. The measurement results showed the resistivity change was nonlinear but displayed nearly linear behavior within a specific range of compressive stress. The slope of this change increased with larger specimen cross-section, shorter electrode distance, and a smaller value for the intermediate resistor in the electric circuit. A regression analysis was conducted to predict the change in resistivity of SSM under nondestructive compressive stress, while taking these effects into account.

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Mechanisms of carbon black in multifunctional cement matrix: Hydration and microstructure perspectives

Cited by 32 publications

References 46 publications

Synergistic Effect of Yak Dung Fiber and Yak Dung Ash on the Mechanical and Shrinkage Properties of Cement Mortar

Synergistic Effect of Yak Dung Fiber and Yak Dung Ash on the Mechanical and Shrinkage Properties of Cement Mortar

Structural Carbon-Enhanced Cementitious Thermoelectric Generators (TEGs): Optimal Energy Filtering and TEG Design for Outstanding Energy Harvesting

Stress Self-sensitivity of Carbon Black-filled Mortar under Nondestructive Compression and the Effects of Electric Circuit and Specimen Dimensions

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