Nickel plated carbon nanotubes reinforcing concrete composites: from nano/micro structures to macro mechanical properties
View/
Accepted manuscript (1.993Mb)
Download
Publication date
2021-02Keyword
Carbon nanotubesCarbon nanofibers
Carbon nanofibres
Carbon nanotubes and nanofibers
Carbon nanotubes and nanofibres
Nanocomposites
Mechanical properties
Microstructural analysis
Rights
© 2020 Elsevier. Reproduced in accordance with the publisher's self-archiving policy. This manuscript version is made available under the CC-BY-NC-ND 4.0 license.Peer-Reviewed
YesMetadata
Show full item recordAbstract
Owing to their small size, good wettability, uniform dispersion ability and high thermal properties, the nickel-plated carbon nanotubes (Ni-CNTs) with different aspect ratios are used to reinforce reactive powder concrete (RPC) through modifying the nano/micro- structural units of concrete. Incorporating only 0.075 vol% of Ni-CNTs (0.03 vol% of CNTs) can significantly increase mechanical properties of RPC. The enhancement effect on compressive strength caused by the incorporation of Ni-CNTs with aspect ratio of 1000 reaches 26.8%/23.0 MPa, mainly benefiting from the high polymerization C-S-H gels, low porosity, and refined pore structure. The 33.5%/1.92 MPa increases of flexural strength can be attributed to the decrease of large pore, original cracks, molar ratio of CaO to SiO2, and gel water content when Ni-CNTs with aspect ratio of 125 are added. Ni-CNTs with aspect ratio of 1500 have the largest utilization rate of being pulled-out, resulting from the improvement of dispersibility and the pining effect of nickel coating and then leading to the increased toughness. Therefore, incorporating Ni-CNTs can fundamentally modify the nano/micro- scale structural nature of RPC, providing a bottom-up approach for controlling the properties of RPC.Version
Accepted manuscriptCitation
Dong S, Wang D, Ashour AF et al (2021) Nickel plated carbon nanotubes reinforcing concrete composites: from nano/micro structures to macro mechanical properties. Composites Part A: Applied Science and Manufacturing. 141: 106228.Link to publisher’s version
https://doi.org/10.1016/j.compositesa.2020.106228Type
ArticleCollections
Related items
Showing items related by title, author, creator and subject.
-
Polynuclear complexes as precursor templates for hierarchical microporous graphitic carbon: An unusual approachA highly porous carbon was synthesized using a coordination complex as an unusual precursor. During controlled pyrolysis, a trinuclear copper complex, [CuII3Cl4(H2L)2]·CH3OH, undergoes phase changes with melt and expulsion of different gases to produce a unique morphology of copper-doped carbon which, upon acid treatment, produces highly porous graphitic carbon with a surface area of 857 m2 g–1 and a gravimetric hydrogen uptake of 1.1 wt % at 0.5 bar pressure at 77 K.
-
Dolomite study for in situ CO 2 capture for chemical looping reformingThe non-isothermal kinetic and thermal behaviour of a naturally formed dolomite in conditions that approach in situ CO2 capture in chemical looping reforming, were investigated. The performance of this dolomite was studied at micro-scale in ‘dry’ conditions, as well as at macro-scale in ‘dry’ and ‘wet’ conditions to investigate the effects of scale (3 mg, 2.5 g), partial pressures of CO2 (<15 kPa) and steam, and deactivation upon limited cycling. The carbonation and calcination kinetics were modelled using an improved iterative Coats–Redfern method. Increasing CO2 partial pressures on the ‘dry’ macroscale exacerbated the experimental carbonation conversions in an inversely proportional trend when compared with those at micro-scale. The presence of steam had a positive effect on CO2 chemisorption. Steam had a negligible influence on the calcination activation energies. The activation energies of carbonation were increased for the experiments at the highest CO2 partial pressures under wet conditions.
-
Gas purification by short cycle pressure swing adsorption. Experimental and theoretical studies of a fixed bed adsorption process for the separation of carbon dioxide from air at ambient temperatures using molecular sieve 5A and activated charcoal adsorbents.An experimental pressure swing adsorption unit has been constructed and used to investigate the separation of carbon dioxide from carbon dioxide enriched air using both an activated carbon and a type 5A molecular sieve adsorbent. Continuous, cyclic operation was achievedusing a pair of fixed bed adsorbers. At any one time the feed gas entered one bed at a high pressure and part of the purified gas was returned to the other bed at a reduced pressure to provide countercurrent regeneration of the adsorbent. The beds of adsorbent used were each nominally 0.165m diameter and Im. deep. Separations were carried out at approximately ambient temperature using air flow rates in the range 0.15 to 0.95 kg/m2s and inlet carbon dioxide concentrations'in the range 0.1 to 1.5% v/v. Adsorption pressures of 2 to 6.4 bar were examined, the desorption pressure being maintained throughout at essentially 1.0 bar. The period time was varied from 30 to 900 seconds and the revert ratio (i. e. the ratio of the product gas returned for desorption to the total feed rate to the unit) was varied from 0 to 1.0. The carbon dioxide separation efficiency was found to increase markedly as the adsorption pressure and the revert ratio were increased whereas it was relatively insensitive to variations in feed rate and, more particularly, feed concentration. The performance of the molecular sieve adsorbent was found to be very sensitive to the presence of moisture in the feed gas. In contrast the carbon dioxide efficiencies observed with Lhe activated carbon were unaffected by the presence of small amounts (circa 100 ppm) of moisture in the feed. A theoretical model has been proposed for predicting the performance of pressure swing adsorption systems of the type investigated and approximate analytical equations and more precise numerical techniques have been established to represent its solution. The approximate analytical solutions were found to give close agreement with the more precise methods examined under conditions corresponding to low values of a dimensionless period time parameter. The proposed theoretical model incorporates an effective irean mass transfer coefficient to represent the diffusion process within the adsorbent particles. Methods for estimation of the value of this coefficient based on the limiting conditions of a periodic constant surface flux or a periodic constant surface concentration are presented. The experimental performance data were analysed in terms of the proposed analytical solution to give values of the apparent solid phase mass transfer coefficient for comparison with those predicted theoretically. In general the apparent experimental values were consistently less than the predicted values. In addition the relationship between the experimental and predicted coefficients was found to be dependent on both the nature of the adsorbent and a parameter formed by the product of the revert ratio and the adsorption to desorption pressure ratio. Empirical correlating equations which incorporate this dependence are presented.
