Influence of Crack Depth on Chloride Transport of Cracked Self-Compacting Concrete under Non-Steady State Migration Test

2011 ◽  
Vol 328-330 ◽  
pp. 1331-1334
Author(s):  
Song Mu ◽  
Geert de Schutter ◽  
Bao Guo Ma
Keyword(s):  
Chloride Transport ◽  
Crack Depth ◽  
Chloride Concentration ◽  
Chloride Content ◽  
Point Of View ◽  
Water Soluble ◽  
Test Method ◽  
Migration Test ◽  
Self Compacting Concrete ◽  
Chloride Migration

From a physical and mechanical point of view, concrete cracking is hard to avoid. So, it is meaningful to study the influence of crack depths on chloride transport in cracked self-compacting concrete. Following the NT BUILD 492 chloride migration test method, water soluble chloride conetnt, acid soluble chloride content and penetration depth were determined on cracked concrete samples which were prepared by artificial crack method. Afterwards, the migration coefficients were obtained by curve fitting on water soluble chloride contents and penetration depths seperately. The results show that the influence of crack depth on chloride concentration of concrete is significant for the concrete zone deeper than 20 mm from the surface. Secondly, the influential zone caused by the crack is limited to a distance of 10 mm at both sides from the crack. Thirdly, the existing equation of chloride transport is not applicable to concrete with different crack depths.

Chloride Binding of Self-Compacting Concrete with Different Crack Depths under Electric Migration Test

2011 ◽  
Vol 105-107 ◽  
pp. 957-960
Author(s):  
Song Mu ◽  
Bao Guo Ma ◽  
Geert de Schutter ◽  
Shou Wei Jian
Keyword(s):  
Crack Depth ◽  
Chloride Content ◽  
Chloride Ions ◽  
Test Method ◽  
Cement Matrix ◽  
Chloride Binding ◽  
Migration Test ◽  
Cracked Concrete ◽  
Chloride Migration ◽  
Binding Isotherms

Cracks can form a shortcut for transport of chloride ions in concrete structure, and provide more opportunities for chloride ions to contact and bind with cement matrix. Following the NT BUILD 492 chloride migration test method, chloride content were determined on cracked concrete samples which were prepared by artificial crack method. The results shows crack depth increased from 0 mm to 31.4 mm almost did not exert pronounced effects on chloride binding of concrete under the migration test.Besides, the binding parameter of linear binding isotherms almost did not change.

scholarly journals The Rapid Chloride Migration Test in Assessing the Chloride Penetration Resistance of Normal and Lightweight Concrete

2021 ◽  
Vol 11 (16) ◽  
pp. 7251
Author(s):  
Jorge Pontes ◽  
José Alexandre Bogas ◽  
Sofia Real ◽  
André Silva
Keyword(s):  
Lightweight Concrete ◽  
Chloride Transport ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Migration Test ◽  
Simple Method ◽  
Chloride Migration ◽  
Binder Ratio ◽  
Chloride Penetration Resistance ◽  
Water Binder Ratio

Chloride-induced corrosion has been one of the main causes of reinforced concrete deterioration. One of the most used methods in assessing the chloride penetration resistance of concrete is the rapid chloride migration test (RCMT). This is an expeditious and simple method but may not be representative of the chloride transport behaviour of concrete in real environment. Other methods, like immersion (IT) and wetting–drying tests (WDT), allow for a more accurate approach to reality, but are laborious and very time-consuming. This paper aims to analyse the capacity of RCMT in assessing the chloride penetration resistance of common concrete produced with different types of aggregate (normal and lightweight) and paste composition (variable type of binder and water/binder ratio). To this end, the RCMT results were compared with those obtained from the same concretes under long-term IT and WDT. A reasonable correlation between the RCMT and diffusion tests was found, when slow-reactive supplementary materials or porous lightweight aggregates surrounded by weak pastes were not considered. A poorer correlation was found when concrete was exposed under wetting–drying conditions. Nevertheless, the RCMT was able to sort concretes in different classes of chloride penetration resistance under distinct exposure conditions, regardless of the type of aggregate and water/binder ratio.

The Effect of Cracks on Chloride Penetration into Concrete

2007 ◽  
Vol 348-349 ◽  
pp. 769-772 ◽  
Author(s):  
In Seok Yoon ◽  
Erik Schlangen ◽  
Mario R. de Rooij ◽  
Klaas van Breugel
Keyword(s):  
Service Life ◽  
Crack Length ◽  
Significant Influence ◽  
Crack Width ◽  
Chloride Transport ◽  
Crack Depth ◽  
Chloride Penetration ◽  
Critical Crack ◽  
Chloride Migration ◽  
Migration Testing

This study is focused on examining the effect of critical crack width in combination with crack depth on chloride penetration into concrete. Because concrete structures have to meet a minimum service-life, critical crack width has become an important parameter. Specimens with different crack width / crack length have been subjected to rapid chloride migration testing (RCM). The results of this study show a critical crack width of about 0.012 mm. Cracks smaller than this critical crack width are considered not to have a significant influence on the rate of chloride transport inwards, while chloride penetration does proceed faster above this critical crack width.

Monitoring the Electrochemical Response of Chloride Sensors Embedded in Cement Paste

2015 ◽  
Vol 1768 ◽  
Author(s):  
F. Pargar ◽  
D.A. Koleva ◽  
E.A.B. Koenders ◽  
K. van Breugel
Keyword(s):  
Cement Paste ◽  
Electrochemical Impedance ◽  
Chloride Concentration ◽  
External Solution ◽  
Chloride Content ◽  
Open Circuit ◽  
Water Soluble ◽  
Free Chloride ◽  
Chloride Determination ◽  
Bound Chloride

ABSTRACTThis work presents the electrochemical behavior of Ag/AgCl electrodes (chloride sensors) in cement paste environment, monitored over a period of 180 days via open circuit potential (OCP) readings and electrochemical impedance spectroscopy (EIS). The EIS response indicates modification of the sensors’ morphology, in particular alteration of the AgCl layers, as a result of continuous chloride penetration into the bulk matrix towards the vicinity of the sensor/cement paste interface. A gradual shift to more cathodic OCP values and stabilization at approximately -1mVSCE to 2mVSCE was observed at the end of the test, reflecting chloride content of 820mM to 930mM in the pore solution surrounding the sensors, which differs 5-10% from the chloride concentration in the external solution. The water soluble chloride content in the cement pate, as destructively measured wet chemically by Volhard method and photometry, was in the range of 1100mM - 1300mM i.e. about 30-50% more than the chloride concentration in the external solution. This difference of maximum 50% in the recorded chloride levels is attributed to the fact that the sensors “read” the average amount of free chloride at the interface sensor/cement paste, while the destructively measured water soluble chloride reflects the average free (with possible contribution of physically bound chloride) in the total volume of analyzed cement paste. It can be concluded that for the conditions of this experiment, more reliable free chloride content is measured via the sensors’ readings. Hence, if chloride thresholds for corrosion initiation are to be determined, the sensors’ readings will be more representative and accurate if compared to destructive water soluble chloride determination.

scholarly journals Autogenous Healing of Cracked Mortar Using Modified Steady-State Migration Test against Chloride Penetration

2021 ◽  
Vol 13 (17) ◽  
pp. 9519
Author(s):  
Fahad ul Rehman Abro ◽  
Abdul Salam Buller ◽  
Tariq Ali ◽  
Zain Ul-Abdin ◽  
Zaheer Ahmed ◽  
...  
Keyword(s):  
Steady State ◽  
Chloride Ions ◽  
Test Method ◽  
The Self ◽  
Chloride Ingress ◽  
Self Healing ◽  
Migration Test ◽  
Steady State Condition ◽  
Chloride Migration ◽  
Short Period

Concrete is a popular building material all over the world, but because of different physiochemical processes, it is susceptible to crack development. One of the primary deterioration processes of reinforced concrete buildings is corrosion of steel bars within the concrete through these cracks. In this regard, a self-healing technique for crack repair would be the best solution to reduce the penetration of chloride ions inside concrete mass. In this study, a rapid chloride migration (RCM) test was conducted to determine the self-healing capacity of cracked mortar. With the help of the RCM test, the steady-state migration coefficient of cracked and uncracked specimens incorporating expansive and crystalline admixtures was calculated. Based on the rate of change of the chloride ion concentrations in the steady-state condition, the migration coefficient was calculated. Furthermore, bulk electrical conductivity tests were also conducted before and after the migration test to understand the self-healing behavior. It was evident from the test results that the self-healing of cracks was helpful to reduce the penetration of chloride ions and that it enhanced the ability of cracked mortar to restrict the chloride ingress. Using this test method, the self-healing capacity of the new self-healing technologies can be evaluated. The RCM test can be an acceptable technique to assess the self-healing ability of cement-based materials in a very short period, and the self-healing capacity can be characterized in terms of the decrease of chloride migration coefficients.

scholarly journals Effects of load-induced micro-cracks on chloride penetration resistance in different types of concrete

2020 ◽  
Vol 53 (6) ◽  
Author(s):  
Nicoletta Russo ◽  
Matteo Gastaldi ◽  
Pietro Marras ◽  
Luca Schiavi ◽  
Alberto Strini ◽  
...  
Keyword(s):  
Crack Width ◽  
Crack Depth ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Migration Test ◽  
Exposure Test ◽  
Durability Design ◽  
Micro Cracks ◽  
Chloride Migration ◽  
Chloride Penetration Resistance

AbstractChloride penetration resistance of concrete is one of the key parameters for the durability design of reinforced concrete structures located in chloride-bearing environments. In all the current available durability models, service life is evaluated considering concrete in uncracked conditions, which is rarely found in practice. This work investigates chloride penetration resistance of concrete in uncracked and micro-cracked configurations, evaluated in terms of chloride migration coefficient through non-steady state migration test (Rapid Chloride Migration test). Prismatic specimens were manufactured considering six different concrete types and two different times of curing. In micro-cracked configuration, cracks were obtained with a specifically developed loading procedure. Micro-cracks were characterized at the end of the exposure test, in terms of crack width at the exposed surface and crack depth. Results showed that cracks were 5–70 μm wide and up to 40 mm deep, always causing an increase in chloride penetration, that should be evaluated considering both crack width and crack depth, with respect to sound conditions. The effects on the chloride penetration seemed to be more pronounced on the more impervious concretes.

scholarly journals Using the Steady-State Chloride Migration Test to Evaluate the Self-Healing Capacity of Cracked Mortars Containing Crystalline, Expansive, and Swelling Admixtures

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1865 ◽  
Author(s):  
Fahad ul Rehman Abro ◽  
Abdul Salam Buller ◽  
Kwang-Myong Lee ◽  
Seung Yup Jang
Keyword(s):  
Steady State ◽  
Diffusion Coefficients ◽  
Chloride Ions ◽  
Test Method ◽  
The Self ◽  
Self Healing ◽  
Migration Test ◽  
Stage Of Development ◽  
Chloride Migration ◽  
Cement Based Materials

Interest in self-healing-crack technologies for cement-based materials has been growing, but research into such materials remains in the early stage of development and standardized methods for evaluating healing capacity have not yet been established. Therefore, this study proposes a test method to evaluate the self-healing capacity of cement-based materials in terms of their resistance to chloride penetration. For this purpose, the steady-state chloride migration test has been used to measure the diffusion coefficients of cracked mortar specimens containing crystalline, expansive, and swelling admixtures. The results of the present study show that the time to reach a quasi-steady-state decreased and the diffusion coefficients increased as the potential increased because of the potential drop inside the migration cell and self-healing that occurred during the test. Therefore, use of a high potential is recommended to minimize the test duration, as long as the temperature does not rise too much during the test. Using this test method, the self-healing capacity of the new self-healing technologies can be evaluated, and an index of self-healing capacity is proposed based on the rate of charged chloride ions passing through a crack.

scholarly journals Numerical Simulation of Non-Uniformly Distributed Corrosion in Reinforced Concrete Cross-Section

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3975
Author(s):  
Magdalena German ◽  
Jerzy Pamin
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Chloride Transport ◽  
Chloride Concentration ◽  
Corrosion Current ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Initiation Phase ◽  
Chloride Corrosion ◽  
Cover Thickness

Reinforced concrete structures can be strongly damaged by chloride corrosion of reinforcement. Rust accumulated around rebars involves a volumetric expansion, causing cracking of the surrounding concrete. To simulate the corrosion progress, the initiation phase of the corrosion process is first examined, taking into account the phenomena of oxygen and chloride transport as well as the corrosion current flow. This makes it possible to estimate the mass of produced rust, whereby a corrosion level is defined. A combination of three numerical methods is used to solve the coupled problem. The example object of the research is a beam cross-section with four reinforcement bars. The proposed methodology allows one to predict evolving chloride concentration and time to reinforcement depassivation, depending on the reinforcement position and on the location of a point on the bar surface. Moreover, the dependence of the corrosion initiation time on the chloride diffusion coefficient, chloride threshold, and reinforcement cover thickness is examined.

scholarly journals A Review on Coordination Properties of Al(III) and Fe(III) toward Natural Antioxidant Molecules: Experimental and Theoretical Insights

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2603
Author(s):  
Luana Malacaria ◽  
Giuseppina Anna Corrente ◽  
Amerigo Beneduci ◽  
Emilia Furia ◽  
Tiziana Marino ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Natural Antioxidants ◽  
Point Of View ◽  
Water Soluble ◽  
Natural Antioxidant ◽  
Theoretical Point ◽  
Structure And Properties ◽  
Coordination Properties ◽  
Soluble Molecule ◽  
Living Organisms

This review focuses on the ability of some natural antioxidant molecules (i.e., hydroxycinnamic acids, coumarin-3-carboxylic acid, quercetin, luteolin and curcumin) to form Al(III)- and Fe(III)-complexes with the aim of evaluating the coordination properties from a combined experimental and theoretical point of view. Despite the contributions of previous studies on the chemical properties and biological activity of these metal complexes involving such natural antioxidants, further detailed relationships between the structure and properties are still required. In this context, the investigation on the coordination properties of Al(III) and Fe(III) toward these natural antioxidant molecules might deserve high interest to design water soluble molecule-based metal carriers that can improve the metal’s intake and/or its removal in living organisms.

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