scholarly journals Development of a Novel Methodology to Assess the Corrosion Threshold in Concrete Based on Simultaneous Monitoring of pH and Free Chloride Concentration

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3101 ◽  
Author(s):  
Yurena Femenias ◽  
Ueli Angst ◽  
Fabrizio Moro ◽  
Bernhard Elsener
Keyword(s):  
Chloride Concentration ◽  
Data Interpretation ◽  
Electrode System ◽  
Potentiometric Sensors ◽  
Engineering Practice ◽  
Free Chloride ◽  
Two Parameters ◽  
Condition Assessments ◽  
Traditional Indicator

Both the free chloride concentration and the pH of the concrete pore solution are highly relevant parameters that control corrosion of the reinforcing steel. In this paper, we present a method to continuously monitor these two parameters in-situ. The approach is based on a recently developed electrode system that consists of several different potentiometric sensors as well as a data interpretation procedure. Instrumented mortar specimens containing different amounts of admixed chlorides were exposed to accelerated carbonation, and changes in free chloride concentration and pH were monitored simultaneously over time. The results revealed the stepwise decrease in pH as well as corresponding increases in free chlorides, resulting from the release of bound chlorides. For a pH drop of about 1 unit (from pH 13.5 down to pH 12.5), the free chloride concentration increased up to 1.5-fold. We continuously quantified the ratio Cl−/OH− that increased steeply with time, and was found to exceed a critical corrosion threshold long before carbonation can be detected with traditional indicator spray testing, even at admixed chloride contents in the order of allowable limits. These results can strongly influence the decision-making in engineering practice and it is expected to significantly improve condition assessments of reinforced concrete structures.

scholarly journals THE EFFECT OF EPITHELIAL REMNANT AND WHOLE ORGAN GRAFTS OF THYMUS ON THE RECOVERY OF THYMECTOMIZED IRRADIATED MICE

1969 ◽  
Vol 129 (6) ◽  
pp. 1235-1246 ◽  
Author(s):  
Esther F. Hays
Keyword(s):  
Direct Action ◽  
Lymphoid Cells ◽  
Lymphoid Tissues ◽  
Functional Development ◽  
Reticular Cells ◽  
Microscopic Morphology ◽  
Two Parameters ◽  
A Minor ◽  
Cellular Components

Work has been presented which suggests that thymus epithelial reticular cells are not effective in restoring the microscopic morphology of lymphoid tissues and their immunologic capacities. They function in recruiting precursors of thymus lymphocytes from the host animals to produce an organ which, after it becomes architecturally normal, can reconstitute the defective host. Intact thymus grafts in situ from 10–14 days, but not for shorter periods of time, have been shown to result in a return toward normal of these two parameters. Evidence is offered to show that few dividing cellular components in the lymphoid tissue originate from the thymus remnant grafts, and that a minor cellular component is contributed by the intact grafts. These data support the concept that the structural and functional development of the lymphatic tissue in thymectomized animals is dependent on thymus lymphoid cells and/or their products, and that the epithelial-reticular cells do not have a direct action in peripheral lymphoid reconstitution.

Size Effects on Photocatalytic H2 Generation with CdSe/CdS Core-Shell Nanocrystals

2015 ◽  
Vol 229 (1-2) ◽  
Author(s):  
Florian Ehrat ◽  
Thomas Simon ◽  
Jacek K. Stolarczyk ◽  
Jochen Feldmann
Keyword(s):  
Hydrogen Generation ◽  
Aqueous Dispersion ◽  
Core Shell ◽  
Ni Nanoparticles ◽  
Cdse Core ◽  
Photocatalytic Hydrogen Generation ◽  
Generation Capacity ◽  
Photocatalytic H2 Generation ◽  
Two Parameters

AbstractCdSe/CdS core-shell nanocrystals with controlled CdS shell thickness and CdSe core size were synthesized for several different values of these two parameters. The particles in aqueous dispersion were in situ decorated with Ni nanoparticles and evaluated for photocatalytic hydrogen generation capacity. The highest H

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

In situ micropuncture study of pancreatic duct pH

1980 ◽  
Vol 238 (3) ◽  
pp. G263-G268 ◽  
Author(s):  
C. R. Caflisch ◽  
S. Solomon ◽  
W. R. Galey
Keyword(s):  
Chloride Concentration ◽  
Flow Conditions ◽  
Buffer Solutions ◽  
Micropuncture Study ◽  
Glass Membrane ◽  
Rabbit Pancreas ◽  
Alkaline Fluid ◽  
Ph Microelectrodes ◽  
Chloride Concentrations

The pH and chloride concentration in the extralobular duct system of the rabbit pancreas was investigated by using glass-membrane pH microelectrodes and microsampling techniques. The response of pH microelectrodes was compared to that of a pH macroelectrode system in buffer solutions containing common interfering substances and it was found that the electrodes were insensitive to these substances. Final pancreatic juice electrolyte concentrations and osmolality were found to be similar to that observed by others. Under free-flow conditions, a significant pH gradient was found between small extralobular ducts (7.47) and final juice (8.03). This gradient was nearly obliterated on stimulation with secretin. Duct chloride concentrations were found to be similar in all duct sizes and final juice under unstimulated conditions and after stimulation with secretin. It is concluded that glass-membrane pH microelectrodes are reliable and accurate indicators of pH in this system. The present experiments suggest that the entire extralobular ductal system may participate in the secretion of an alkaline fluid.

S7-13 Detecting Voids in Tendon Ducts of Post-Tensioned Bridge Girders

2013 ◽  
Vol 639-640 ◽  
pp. 1015-1020
Author(s):  
Gui Hua Dai ◽  
Xian Yan Zhou
Keyword(s):  
Frequency Domain ◽  
Data Interpretation ◽  
Bridge Girders ◽  
Impact Echo ◽  
Condition Evaluation ◽  
Load Carrying ◽  
History Of ◽  
Post Tensioned

The tendon ducts in post-tensioned bridge girders must be grouted fully so as to prevent water and oil stain from entering the ducts, which will decrease the durability and load-carrying capacity of post-tensioned bridges badly. This paper describes the motivations for and recent history of Impact-Echo (IE) scanning applications to internal grout condition evaluation of tendon ducts in post-tensioned girders. The tendon ducts’ internal injection quality of a railway bridge in Yichang city was evaluated using IE technology. During the in-situ testing, the IE signals were collected firstly, then the transformation from the time to the frequency domain was carried out using the principles of the fast Fourier transform, data interpretation was much simpler and quicker in the frequency domain. The grout condition of tendon ducts could be determined according to the frequency analysis, poorly grouted sections can be differentiated from the well-grouted sections within the tendon ducts. Results show that the IE method can be employed to detect voids in the grouted tendon ducts of many types of post-tensioned structures.

In situ study on the influence of bicarbonate, chloride and outer electrode potential on crevice corrosion occurrence and development of X70 steel

2019 ◽  
Vol 66 (5) ◽  
pp. 651-660 ◽  
Author(s):  
Qian Hu ◽  
Saiwen Lu ◽  
Jing Liu ◽  
Feng Huang
Keyword(s):  
Corrosion Behavior ◽  
Electrode Potential ◽  
Crevice Corrosion ◽  
Chloride Concentration ◽  
Current Density Distribution ◽  
Outer Electrode ◽  
Active Dissolution ◽  
Content Type ◽  
Modeling And Experiments

Purpose The purpose of this paper is to clarify the influence of bicarbonate, chloride and outer electrode potential on crevice corrosion occurrence and development of X70 steel. Design/methodology/approach The crevice corrosion behavior in NaHCO3 and NaCl solutions was investigated through modeling and experiments. The electrode potential and current density distribution were simulated, and the acidification of crevice solution was monitored in situ. Findings The bicarbonate concentration and outer electrode potential remarkably influenced the occurrence of crevice corrosion. The former changes the passivation curves, and the latter alters the initial potential. Moreover, chloride concentration exerted minimal influence. The location of acidification and pitting occurrences depended on the potential difference between the outer electrode and electrode at the active dissolution current peak. Originality/value This study provides a better understanding of the crevice corrosion behavior and mechanism under natural conditions.

In Situ Potentiometry and Ellipsometry: A Promising Tool to Study Biofouling of Potentiometric Sensors

2016 ◽  
Vol 88 (6) ◽  
pp. 3009-3014 ◽  
Author(s):  
Grzegorz Lisak ◽  
Thomas Arnebrant ◽  
Andrzej Lewenstam ◽  
Johan Bobacka ◽  
Tautgirdas Ruzgas
Keyword(s):  
Potentiometric Sensors ◽  
Promising Tool
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