Effect of bottom-up placing of self-compacting concrete on microstructure of rebar-concrete interface

Dybeł, Piotr

doi:10.1016/j.conbuildmat.2021.124359

Cited by 6 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, in the bottom-up technology, there is no risk of introducing extra air into the mixture connected with the dropping of concrete. These observations were also confirmed by the studies [ 16 ]. CT images and the visual inspection of the surface after splitting clearly indicated that with the above-mentioned technology, the quality of SCC surrounding the rebar was significantly improved in comparison with the top-down placed concrete.…”

Section: Discussionsupporting

confidence: 87%

“…However, one could notice that samples located in the top part of the elements acquired the lowest values of compressive strength, regardless of the placing method. A-sample used for pull-out test; C-sample used in another study [16]; COV-coefficient of variation.…”

Section: Compressive Strengthmentioning

confidence: 99%

“… A—sample used for pull-out test; C—sample used in another study [ 16 ]; COV—coefficient of variation. …”

Section: Figurementioning

confidence: 99%

“…Moreover, in spite of the great research interest in the subject, studies related to SCCs have so far received little attention. Known solutions and analyses of the bond failure mechanism do not consider the variant of thr bottom-up placing of the SCC mixture, which, according to [ 16 ], significantly affects the microstructure of the rebar–concrete interface. In view of the discussed problems, the aim of this work is to analyze the influence of placing the self-compacting mixture—from the top and bottom of the form—on the mechanism of bond failure between rebar and SCC.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Dybeł

Kucharska

2021

Materials

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionsupporting

confidence: 87%

Section: Compressive Strengthmentioning

confidence: 99%

“… A—sample used for pull-out test; C—sample used in another study [ 16 ]; COV—coefficient of variation. …”

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Dybeł

Kucharska

2021

Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“… Ultrasound tomography, which can be used to visualize the internal behavior of a concrete structure [ 18 , 19 ]. X-ray microtomography (XCT, µCT, X-ray CT), covering the entire spectrum of materials [ 20 , 21 ]; applications of extended XCT scanning and neutron CT are also known [ 22 ]. …”

Section: Introductionmentioning

confidence: 99%

Application of X-ray Computed Tomography to Verify Bond Failures Mechanism of Fiber-Reinforced Fine-Grain Concrete

et al. 2022

View full text Add to dashboard Cite

This paper proposes the use of X-ray computed tomography (µCT, xCT) measurements together with finite element method (FEM) numerical modelling to assess bond failures mechanism of fiber-reinforced fine-grain concrete. Fiber-reinforced concrete is becoming popular for application in civil engineering structures. A dynamically developing topic related to concretes is the determination of bond characteristics. Nowadays, modern technologies allow inspecting the inside of the element without the need to damage its structure. This paper discusses the application of computed tomography in order to identify damage occurring in the structure of fiber-reinforced fine-grain concrete during bond failure tests. The publication is part of a larger study to determine the bonding properties of Ukrainian steel fibers in fine-grain concrete. The authors focused on the visual evaluation of sections obtained from tomographic data. Separately, the results of volumetric analysis were presented to quantitatively assess the changes occurring in the matrix structure. Finite element analysis is an addition to the substantive part and allows us to compare real damage areas with theoretical stress concentration areas. The result of the work is the identification of a path that allows verification of the locations where matrix destruction occurs.

show abstract

Experimental investigation of corrosion effect on bending deflection of shield tunnel segment containing transverse cracks

Zhang

Jin

et al. 2022

Structural Concrete

View full text Add to dashboard Cite

Corrosion of the steel rebar will be generated in the cracked concrete of the shield tunnel during the operation period, which will reduce the bending performance of the tunnel segment. In this study, the effect of the rebar corrosion on the bending deflection of the shield tunnel segment that contains transverse cracks is investigated by experimental tests. The initial transverse cracks of the segment are simulated by a bending load device, and the galvanostatic method is used to simulate the corrosion of the segment rebar. The degradation of the segment bending deflection after the rebar corrosion process is measured and compared with the non‐corroded segment. The results reveal that when the depth of the transverse crack does not exceed the thickness of the protective layer, the corrosion of the rebar has little effect on the bending degradation. However, when the width and depth of the transverse crack reach approximately 1.2 and 210 mm, respectively, the degradation rate of bending deflection begins to increase rapidly.

show abstract

Effect of bottom-up placing of self-compacting concrete on microstructure of rebar-concrete interface

Cited by 6 publications

References 19 publications

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

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

Application of X-ray Computed Tomography to Verify Bond Failures Mechanism of Fiber-Reinforced Fine-Grain Concrete

Experimental investigation of corrosion effect on bending deflection of shield tunnel segment containing transverse cracks

Contact Info

Product

Resources

About