scholarly journals The influence of defects at the steel/concrete interface for pitting corrosion initiation studied through X-ray Computed Tomography and image analysis

2019 ◽  
Vol 289 ◽  
pp. 10011
Author(s):  
Emanuele Rossi ◽  
Timo Nijland ◽  
Oğuzhan Çopuroğlu ◽  
Rob Polder ◽  
Branko Šavija
Keyword(s):  
Computed Tomography ◽  
Image Analysis ◽  
Reinforced Concrete ◽  
Pitting Corrosion ◽  
Ct Scans ◽  
Volume Loss ◽  
Air Voids ◽  
X Ray ◽  
X Ray Computed ◽  
Concrete Interface

Although corrosion of reinforcement is a well-known issue for the construction industry, there are still open questions about some fundamentals of corrosion in reinforced concrete. These points include, among others, which are the most sensitive locations of the steel/concrete interface for pitting corrosion to initiate and to propagate. In this study, X-ray computed tomography (CT-scan) is used to characterize eight 20-years-old reinforced concrete cores naturally deteriorated due to chloride-induced corrosion. The volume loss due to corrosion of the reinforcement was quantified through image analysis of CT-scans. The volume loss of the steel was found to be higher for steel rebars embedded in Portland cement specimens rather than in blended cement specimens. Furthermore, CT-scans revealed that the deepest and most frequent corrosion pits, as well as the consequent highest volume loss of steel, were present at the portion of the reinforcement closer to the outdoor environment and in proximity to air voids at the steel/concrete interface. As a consequence, the highest decrease of structural performance of the rebars would be likely localized at those locations. Therefore, the presence of interfacial air voids should be considered as relevant factor when assessing the risk of corrosion of reinforced concrete structures.

X-RAY TOMOGRAPHY STUDIES OF PREHISTORIC CERAMIC ARTIFACTS

2014 ◽  
Vol 27 ◽  
pp. 1460135
Author(s):  
CARMEN PAVEL ◽  
FLORIN CONSTANTIN ◽  
COSMIN IOAN SUCIU ◽  
ROXANA BUGOI
Keyword(s):  
Computed Tomography ◽  
Cultural Heritage ◽  
Nuclear Physics ◽  
Structural Information ◽  
Ct Scans ◽  
Visual Examination ◽  
X Ray ◽  
X Ray Computed ◽  
Internal Configuration ◽  
Non Destructive

X-ray Computed Tomography (CT) is a powerful non-destructive technique that can yield interesting structural information not discernible through visual examination only. This paper presents the results of the CT scans of four objects belonging to the Romanian cultural heritage attributed to the Vinča, Cucuteni and Cruceni-Belegiš cultures. The study was performed with an X-ray tomographic device developed at the Department for Applied Nuclear Physics from Horia Hulubei National Institute for Nuclear Physics and Engineering in Măgurele, Romania. This apparatus was specially designed for archaeometric studies of low-Z artifacts: ceramic, wood, bone. The tomographic investigations revealed the internal configuration of the objects and provided information about the degree to which the previous manipulations affected the archaeological items. Based on the X-ray images resulting from the CT scans, hints about the techniques used in the manufacturing of the artifacts were obtained, as well as some indications useful for conservation/restoration purposes.

scholarly journals Fiber orientation quantification utilizing X-ray micro-computed tomography

2020 ◽  
pp. 002199832096255
Author(s):  
Jennifer M Sietins ◽  
Jessica C Sun ◽  
Daniel B Knorr Jr
Keyword(s):  
Computed Tomography ◽  
Fiber Orientation ◽  
Mechanical Performance ◽  
Ct Scans ◽  
Micro Computed Tomography ◽  
Orientation Data ◽  
Orientation Analysis ◽  
X Ray ◽  
Software Analysis ◽  
X Ray Computed

It is well known that the mechanical performance of composite materials is highly dependent on the fiber orientation. Several techniques have historically been used to quantify fiber orientation experimentally. Newer methods have involved 3 D X-ray computed tomography (CT) scans due to the high resolution that is now achievable within a laboratory setting. The accuracy of the analysis, however, is a function of the resulting scan image quality and the specific parameters influencing the resulting orientation analysis. This report summarizes a methodology to quantify fiber orientation from 3 D CT scans. Optimal scanning parameters are presented taking into account both the necessary resolution, geometric unsharpness, and the scan volume size. The influence of varied software analysis parameters and their effects on the resulting orientation data is discussed. The selection of software analysis parameters was independently validated with optical microscopy on a sample with only two fibers. Lastly, the orientation analysis was applied to a 0/+45/−45/90 composite to demonstrate this technique on a larger scale.

scholarly journals Quantitative Evaluation of Soil Structure and Strain in Three Dimensions under Shear Using X-ray Computed Tomography Image Analysis

2021 ◽  
Vol 7 (11) ◽  
pp. 230
Author(s):  
Shintaro Nohara ◽  
Toshifumi Mukunoki
Keyword(s):  
Computed Tomography ◽  
Image Analysis ◽  
Shear Zone ◽  
Soil Structure ◽  
Three Dimensions ◽  
Image Correlation ◽  
Ct Scanner ◽  
Zone Formation ◽  
X Ray ◽  
X Ray Computed

The objective of this study is to quantitatively evaluate the soil structure behavior when under shear stress to understand the mechanism of shear zone formation using a micro-focus X-ray computed tomography (CT) scanner to visualize the internal samples without causing disturbance. A new image-analysis method was proposed to systematically evaluate the particle length and direction by fitting the particle as an ellipsoid. Subsequently, a direct shear experiment was conducted on soil materials, and shear band was scanned using a micro-focus X-ray CT scanner. After validating the proposed method, the soil structure was evaluated in the shear zone via image analysis on the CT images. Furthermore, the strain inside the specimen was evaluated using digital image correlation. The results showed that a partial change in the particle direction occurred when the volume expansion inside the shear zone exceeded the peak. In addition, the width of the shear zone was ~7.1 times the median grain size of the sand used; however, the region exhibiting a change in the direction of the particles was narrow and confined to the vicinity of the shear plane.

Sign in / Sign up

Export Citation Format

Share Document