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Topics In Concrete
Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 12 Abstracts search results
Document:
22-298
Date:
September 1, 2024
Author(s):
Junhyung Kim and Raissa Douglas Ferron
Publication:
Materials Journal
Volume:
121
Issue:
5
Abstract:
Embedding magnetic particles into cement paste produces a smart material in which the rheological properties of the resultant paste can be actively controlled through the use of magnetorheological (MR) principles. This research investigates the rheological behavior of cement-based MR pastes with and without air entrainment to gain a better understanding of the effects of air-entrained bubbles on MR cement pastes. Such information would be critical for the use of such MR pastes in three-dimensional (3-D) concrete printing applications. It is revealed that the incorporation of entrained air increases the MR response, and this effect is related to the bubble-bridge effect.
DOI:
10.14359/51742113
22-063
January 1, 2023
G. H. Nalon, J. C. L. Ribeiro, L. G. Pedroti, E. N. D. de Araujo, J. M. F. de Carvalho, G. E. S. de Lima, and S. O. Ferreira
120
1
Post-fire rehydration is an interesting method to recover the structural performance of fire-damaged concrete. This paper evaluated the viability of using cementitious materials containing carbon nanotubes (CNTs) or carbon-black nanoparticles (CBNs) for damage recovery detection and self-monitoring of strain and stress of fire-damaged structures subjected to post-fire curing. Nanomodified mortars were subjected to high temperatures, rehydration, and measurements of capacitive behavior, electrical resistivity, and self-sensing properties. After 600°C and rehydration, mortars with 9.00% of CBN presented the ability of self-detection of damage recovery, as also verified in mortars with 0.4 to 1.20% of CNT and 6.00% of CBN after 400°C and rehydration. The post-fire curing method filled the pores and microcracks of the cementitious matrix with nonconductive rehydration products, increasing their electrical resistivity. Mortars with 0.80 and 1.20% of CNT presented self-monitoring of strain and stress after 400°C and rehydration, as also observed in mortars with 9.00% of CBN after 600°C and rehydration. The post-fire curing process also increased the selfsensing properties because nonconductive rehydration products obstructed conductive stretches, improving tunneling conduction mechanisms rather than contacting conduction. These self-sensing materials are promising alternatives to evaluate post-fire curing processes and self-monitor the strain and stresses of next-generation smart structures.
10.14359/51738459
20-464
November 1, 2021
Aparna S. Deshmukh, Reed T. Heintzkill, Rosalba A. Huerta, and Konstantin Sobolev
118
6
Systematically designed cement mixtures incorporating various proportions of portland cement (PC), high-ferrous Class F fly ash (FA), nanosilica (NS), and nanoalumina (NA) were blended and characterized for rheological response with and without the application of a magnetic field to better understand the effects of doping cement with magnetic material for application in four-dimensional (4D) printing of cementitious smart materials (SM). Control groups doped with industrial-grade magnetite powder (primarily used as pigment) were likewise mixed and characterized to provide contrast to coal-combustion byproduct FA. Mixtures supplemented with ferromagnetic particles showed increased yield stress when exposed to applied magnetic field, leading to non-Newtonian rheological models exhibiting ‘sticky particles’ paradigms as discussed herein. These results suggest that the principle of using an applied magnetic field to modify the flow and slump of cementitious materials extruded through a three-dimensional (3D) printing apparatus is worthy of further pursuit and development.
10.14359/51733128
16-304
May 1, 2018
Fadi Oudah and Raafat El-Hacha
Structural Journal
115
3
The ability to sense the environment and react on thermal and mechanical stimulus make the use of smart materials a promising alternative in the design of structures. The design of concrete plastic hinge regions reinforced using shape memory alloy (SMA), a class of smart material, was considered in this study to further enhance the self-centering ability, while reducing the material direct cost. This was achieved through introducing an innovative detail of concrete plastic hinge regions reinforced using SMA bars. The system was examined experimentally by testing a large-scale concrete beam-column connection and comparing it with steel reinforced counterparts. Test results indicated the ability of the system to achieve a self-centering behavior when subjected to positive and negative bending while sustaining minimal damage. Future research trend should be directed toward mitigating the premature failure of the SMA bars at the anchorage to further use the energy dissipation ability of the SMA bar.
10.14359/51702132
16-080
January 1, 2017
Iman Abavisani, Omid Rezaifar, and Ali Kheyroddin
114
A novel feasibility study was launched into real-time structural behavior controlling and improving properties of flexural reinforced concrete (RC) members, using alternating magnetic field (AMF) and alternating current (AC) electricity of different intensities. Hence, a strong AMF of 0.5 tesla (T) was directly applied to some small-scale RC beams in both pasty and solid phases. To allow for better discussion about the effect of AMF, some compressive cube plain concrete (PC) specimens were prepared and exposed to AMF at the same stages as the RC beams were. Then the results were compared and they were found to correlate with each other. Also, the effect of applying AC of different intensities up to 36 ampere (A) to the steel reinforcement system of RC beams was evaluated. It was observed that applying AMF in pasty phase facilitates concrete placing process for RC structures but it has a marginal effect on structural properties of RC beams. As to solid phase, applying AMF to hardened RC beams affected their structural properties such as load-bearing capacity, deflection, bending stiffness, and ductility during the loading history. Regarding AC, ductility of RC beams was found to increase with increase in current intensity, following a cubic function. The results can be a base for construction of a new generation of smart structures through magnetic fields and electric currents.
10.14359/51689452
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