Influence of detection methods on chloride threshold value for the corrosion of steel reinforcement

2009 ◽  
Vol 23 (5) ◽  
pp. 1902-1908 ◽  
Author(s):  
Jinxia Xu ◽  
Linhua Jiang ◽  
Jingxiang Wang
Keyword(s):  
Threshold Value ◽  
Steel Reinforcement ◽  
Detection Methods ◽  
Chloride Threshold ◽  
Corrosion Of Steel

Anaerobic Corrosion of Reinforcement

2013 ◽  
Vol 569-570 ◽  
pp. 1124-1131 ◽  
Author(s):  
Ross O’Donovan ◽  
Brian D. O’Rourke ◽  
Kieran D. Ruane ◽  
John Justin Murphy
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Product ◽  
Steel Corrosion ◽  
Electrochemical Process ◽  
Steel Reinforcement ◽  
Detection Methods ◽  
Anaerobic Corrosion ◽  
The Subject ◽  
Corrosion Of Steel

Anaerobic corrosion of steel reinforcement is rarely reported and limited literature is available on the subject. Corrosion of steel is an electrochemical process requiring a supply of oxygen in the presence of moisture. Steel corrosion product usually occupies a much larger volume than the un-corroded steel resulting in cracked or spalled concrete. If the supply of oxygen is restricted, black rust may be formed by the process of anaerobic corrosion. Black rust is not expansive, which makes it particularly difficult to detect in reinforced concrete. This paper presents a case study of anaerobic corrosion in the Mizen Bridge, together with an in-depth review of anaerobic corrosion of reinforcement in concrete, outlining black rust formation, characteristics and detection methods.

Influence of Mineral Admixtures on Chloride Threshold Value for the Corrosion of Steel Reinforcement

2011 ◽  
Vol 335-336 ◽  
pp. 1168-1173
Author(s):  
Peng Ping Li ◽  
Jian Bo Xiong ◽  
Zhi Hong Fan ◽  
Sheng Nian Wang
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Average Pore Size ◽  
Threshold Value ◽  
Mineral Admixtures ◽  
Splash Zone ◽  
Tidal Zone ◽  
Average Pore ◽  
Chloride Threshold ◽  
Corrosion Of Steel

The influence of mineral admixtures on chloride threshold value was investigated by EIS method, MIP test and TG test, respectively. The experimental results showed that the chloride threshold value decreased with increasing the fly ash and slag content in composite cementitious. The increasing of fly ash and slag replacement resulted in the decreasing of porosity, average pore size and Ca(OH)2content. The effect of mineral admixtures on the chloride threshold value was the comprehensive results of concrete pore structure and Ca(OH)2content. The chloride threshold value decreased with decreasing the Ca(OH)2content in concrete, and there was an approximate linear relationship between the logarithm of chloride threshold value and the logarithm of CCa(OH)2content when the specimens exposed in tidal zone. The specimen exposed in tidal zone has a higher chloride threshold value than that exposed in splash zone was due to the lower dissolved oxygen around steels in concrete.

The investigation of pH threshold value on the corrosion of steel reinforcement in concrete

2017 ◽  
Vol 19 (3) ◽  
pp. 257-262 ◽  
Author(s):  
Qi Pu ◽  
Yan Yao ◽  
Ling Wang ◽  
Xingxiang Shi ◽  
Jingjing Luo ◽  
...  
Keyword(s):  
Threshold Value ◽  
Steel Reinforcement ◽  
Corrosion Of Steel

Peak detection in sediment - charcoal records: impacts of alternative data analysis methods on fire-history interpretations

2010 ◽  
Vol 19 (8) ◽  
pp. 996 ◽  
Author(s):  
Philip E. Higuera ◽  
Daniel G. Gavin ◽  
Patrick J. Bartlein ◽  
Douglas J. Hallett
Keyword(s):  
Data Analysis ◽  
Fire History ◽  
Threshold Value ◽  
Decomposition Methods ◽  
Peak Detection ◽  
Detection Methods ◽  
Statistical Framework ◽  
Analysis Methods ◽  
Decomposition Models ◽  
Data Analysis Methods

Over the past several decades, high-resolution sediment–charcoal records have been increasingly used to reconstruct local fire history. Data analysis methods usually involve a decomposition that detrends a charcoal series and then applies a threshold value to isolate individual peaks, which are interpreted as fire episodes. Despite the proliferation of these studies, methods have evolved largely in the absence of a thorough statistical framework. We describe eight alternative decomposition models (four detrending methods used with two threshold-determination methods) and evaluate their sensitivity to a set of known parameters integrated into simulated charcoal records. Results indicate that the combination of a globally defined threshold with specific detrending methods can produce strongly biased results, depending on whether or not variance in a charcoal record is stationary through time. These biases are largely eliminated by using a locally defined threshold, which adapts to changes in variability throughout a charcoal record. Applying the alternative decomposition methods on three previously published charcoal records largely supports our conclusions from simulated records. We also present a minimum-count test for empirical records, which reduces the likelihood of false positives when charcoal counts are low. We conclude by discussing how to evaluate when peak detection methods are warranted with a given sediment–charcoal record.

scholarly journals Experimental Assessment of Rebar Corrosion in Concrete Slab Using Ground Penetrating Radar (GPR)

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ahmad Zaki ◽  
Megat Azmi Megat Johari ◽  
Wan Muhd Aminuddin Wan Hussin ◽  
Yessi Jusman
Keyword(s):  
Ground Penetrating Radar ◽  
Structural Damage ◽  
Concrete Slab ◽  
Steel Corrosion ◽  
Steel Reinforcement ◽  
Reinforcement Corrosion ◽  
Dc Power ◽  
Reinforcement Bar ◽  
Ground Penetrating ◽  
Corrosion Of Steel

Corrosion of steel reinforcement is a major cause of structural damage that requires repair or replacement. Early detection of steel corrosion can limit the extent of necessary repairs or replacements and costs associated with the rehabilitation works. The ground penetrating radar (GPR) method has been found to be a useful method for evaluating reinforcement corrosion in existing concrete structures. In this paper, GPR was utilized to assess corrosion of steel reinforcement in a concrete slab. A technique for accelerating reinforcement bar corrosion using direct current (DC) power supply with 5% sodium chloride (NaCl) solution was used to induce corrosion to embedded reinforcement bars (rebars) in this concrete slab. A 2 GHz GPR was used to assess the corrosion of the rebars. The analysis of the results of the GPR data obtained shows that corrosion of the rebars could be effectively localized and assessed.

CONDITIONS OF ODOR THRESHOLD DETERMINATION 2.1 Requirements for the test area Olfactonetric measurement should be undertaken in a roan or area which is kept free frcm odors. There should be an atmosphere of ccmfort and relaxation in the test chamber, which will encourage panel members to concentrate on the testing task and not to be distracted by external sti­ muli. The test should be carried out at roan temperature and normal humi­ dity. 2.2 General conditions for test procedure Odor measurements must be carried out with the help of a team leader, who instructs the panelists and operates the measuring equipment. Ccmnu-nication between the team leader and the panel has to be kept to an abso­ lute minimum. Because of fatigue, the duration of a test series as well as the time of the whole session should be limited. Breaks of at least the same duration as the proceeding test period should be provided. Germany France Nether­ United lands Kingdcm Panel leader yes yes yes yes duration of 15-30 min 20 min 15 min test series duration of breaks 15-30 min 20 min ? 5 min 30 min 2 test 2 hours time of a test 300 tests/ series of period day 20 tests Table 1: General conditions 3. DETECTION METHODS 3.1 Presentation of odor stimulus 3.1.1 Method of limits The most used method for establishing an absolute threshold in en­ vironmental studies is the Method of Limits. In its classical form, the stimuli are presented in alternating ascending and descending series, starting at different points to avoid having the subject fall into a rou­ tine. During this procedure there is a chance that adaptation phenomena may develop. An effort to minimize these effects is for example to use only an ascending series of stimuli. The threshold value for each sepa­ rate test series is defined as a point in-between the last undetected and the first detected point in the stimulus continuum. A modification of the method of limits is the "up and down" method. A stimulus is presented: if the response is positive, the next lower sti­ mulus is presented, if it is negative, the next higher is presented and so on. The primary advantage is, that it automatically concentrates near the mean and a considerable number of observations can be saved.

1986 ◽  
pp. 70-70
Keyword(s):  
Test Procedure ◽  
Test Chamber ◽  
Absolute Threshold ◽  
Threshold Value ◽  
Team Leader ◽  
Test Series ◽  
Detection Methods ◽  
Odor Stimulus ◽  
Primary Advantage ◽  
General Conditions
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