X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology

The effect of different placing methods of the self-compacting concrete (SCC) mix—from the top and from the bottom of the form—on the bond failure mechanism was investigated within the scope of this paper. Existing studies regarding the known mechanisms of bond failure do not consider the bottom-up...

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Autores principales:	Piotr Dybeł, Milena Kucharska
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	computed tomography self-compacting concrete bond mechanism bottom-up placing Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85
Acceso en línea:	https://doaj.org/article/b06d7eac6c744c1899680d36a3eb1317
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spelling	oai:doaj.org-article:b06d7eac6c744c1899680d36a3eb13172021-11-11T17:49:30ZX-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology10.3390/ma142162361996-1944https://doaj.org/article/b06d7eac6c744c1899680d36a3eb13172021-10-01T00:00:00Zhttps://www.mdpi.com/1996-1944/14/21/6236https://doaj.org/toc/1996-1944The effect of different placing methods of the self-compacting concrete (SCC) mix—from the top and from the bottom of the form—on the bond failure mechanism was investigated within the scope of this paper. Existing studies regarding the known mechanisms of bond failure do not consider the bottom-up method of concrete placing, which improves the quality of the concrete microstructure around reinforcing bars. Background tests were performed on panel elements with dimensions of 800 × 480 × 160 mm. Ribbed steel reinforcing bars with a diameter of 16 mm were used in the tests, which were placed horizontally in the forms. A pull-out method was used to investigate the bond strength. X-ray computed tomography (CT) was used as a novel and non-destructive technique that allowed a 3D insight into the bond between the rebar and the concrete after the ultimate bond stress had been reached. The results provided a clear description of the phenomena occurring during the fresh state of concrete in the vicinity of rebars (bleeding, plastic settlement, vertical density variation) and showed their significance for bond mechanisms. Finally, it was demonstrated that placing the mix from the bottom of the form resulted in the same bond failure mechanism for both bars located at the top and the bottom of the panel elements. This was translated into identical bond properties throughout the element with regard to bond stiffness and bond strength. It was found that the described and known mechanisms of bond failure are only an idealized description of the performance of the reinforcing bar-concrete joint. The analysis of the steel–concrete interface (SCI) imaging indicated that, in reality, the forming bond failure mechanisms were a complex process that could be affected by many factors.Piotr DybełMilena KucharskaMDPI AGarticlecomputed tomographyself-compacting concretebond mechanismbottom-up placingTechnologyTElectrical engineering. Electronics. Nuclear engineeringTK1-9971Engineering (General). Civil engineering (General)TA1-2040MicroscopyQH201-278.5Descriptive and experimental mechanicsQC120-168.85ENMaterials, Vol 14, Iss 6236, p 6236 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	computed tomography self-compacting concrete bond mechanism bottom-up placing Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85
spellingShingle	computed tomography self-compacting concrete bond mechanism bottom-up placing Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85 Piotr Dybeł Milena Kucharska X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
description	The effect of different placing methods of the self-compacting concrete (SCC) mix—from the top and from the bottom of the form—on the bond failure mechanism was investigated within the scope of this paper. Existing studies regarding the known mechanisms of bond failure do not consider the bottom-up method of concrete placing, which improves the quality of the concrete microstructure around reinforcing bars. Background tests were performed on panel elements with dimensions of 800 × 480 × 160 mm. Ribbed steel reinforcing bars with a diameter of 16 mm were used in the tests, which were placed horizontally in the forms. A pull-out method was used to investigate the bond strength. X-ray computed tomography (CT) was used as a novel and non-destructive technique that allowed a 3D insight into the bond between the rebar and the concrete after the ultimate bond stress had been reached. The results provided a clear description of the phenomena occurring during the fresh state of concrete in the vicinity of rebars (bleeding, plastic settlement, vertical density variation) and showed their significance for bond mechanisms. Finally, it was demonstrated that placing the mix from the bottom of the form resulted in the same bond failure mechanism for both bars located at the top and the bottom of the panel elements. This was translated into identical bond properties throughout the element with regard to bond stiffness and bond strength. It was found that the described and known mechanisms of bond failure are only an idealized description of the performance of the reinforcing bar-concrete joint. The analysis of the steel–concrete interface (SCI) imaging indicated that, in reality, the forming bond failure mechanisms were a complex process that could be affected by many factors.
format	article
author	Piotr Dybeł Milena Kucharska
author_facet	Piotr Dybeł Milena Kucharska
author_sort	Piotr Dybeł
title	X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
title_short	X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
title_full	X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
title_fullStr	X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
title_full_unstemmed	X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology
title_sort	x-ray ct investigation of bond mechanism in reinforced scc elements of different placement technology
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/b06d7eac6c744c1899680d36a3eb1317
work_keys_str_mv	AT piotrdybeł xrayctinvestigationofbondmechanisminreinforcedsccelementsofdifferentplacementtechnology AT milenakucharska xrayctinvestigationofbondmechanisminreinforcedsccelementsofdifferentplacementtechnology
_version_	1718432019659096064

X-ray CT Investigation of Bond Mechanism in Reinforced SCC Elements of Different Placement Technology

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