scholarly journals Impact of leaching on chloride ingress profiles in concrete

2021 ◽  
Vol 55 (1) ◽  
Author(s):  
Alisa Machner ◽  
Marie Bjørndal ◽  
Aljoša Šajna ◽  
Nikola Mikanovic ◽  
Klaartje De Weerdt
Keyword(s):  
Service Life ◽  
Laboratory Testing ◽  
Chloride Content ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Standard Laboratory ◽  
Total Chloride ◽  
Chloride Profiles ◽  
The Impact

AbstractTo investigate the effect of leaching on chloride ingress profiles in concrete and mortar, we exposed concrete and mortar specimens for 90 and 180 days to two different exposure solutions: 3% NaCl, and 3% NaCl with KOH added to limit leaching. The solutions were replaced weekly. After exposure, we determined total chloride profiles to investigate the chloride ingress, and portlandite profiles to assess the extent of leaching. The results showed that leaching during exposure greatly affects the chloride ingress profiles in mortar and concrete. We found that leaching leads to considerably higher maximum total chloride content and deeper chloride penetration into the concrete than in the specimens where leaching was limited. We recommend therefore that leaching should be taken into account in standard laboratory testing and that more mechanistic service life models should be used to take into account the impact of leaching.

scholarly journals Perpendicular-to-crack chloride ingress in cracked and autonomously healed concrete

2018 ◽  
Vol 199 ◽  
pp. 02011
Author(s):  
Bjorn Van Belleghem ◽  
Philip Van den Heede ◽  
Kim Van Tittelboom ◽  
Nele De Belie
Keyword(s):  
Concrete Structures ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Crack Healing ◽  
Crack Location ◽  
Spray Method ◽  
Surface Visualization ◽  
Chloride Profiles ◽  
Concrete Matrix

Cracks in reinforced concrete structures exposed to a marine environment or de-icing salts can cause major durability issues due do accelerated ingress of chloride ions. In this study, the influence of autonomous crack healing by means of encapsulated polyurethane on the chloride ingress perpendicular to cracks was evaluated. This was done quantitatively by determining perpendicular-to-crack chloride profiles by means of profile grinding followed by potentiometric titration and qualitatively through visualization of the chloride penetration front by means of the AgNO3 spray method. The resulting chloride profiles showed that the healing mechanism was able to reduce the chloride concentrations in the direct vicinity of the crack to a large extent and to reduce the perpendicular-to-crack chloride penetration, especially further away from the exposed surface. Visualization of the chloride penetration front showed some variation in crack healing. For some healed samples almost no additional chloride ingress was found compared to uncracked samples, others showed a slightly enhanced ingress at the crack location but less perpendicular-to-crack chloride penetration compared to untreated cracked samples. Generally, the reduced amount of chlorides present in the concrete matrix due to crack healing will enhance the durability and service life of concrete structures.

Influence of Boundary and Initial Condition on Durability of Concrete Structures Exposed to Chloride Environment

2012 ◽  
Vol 166-169 ◽  
pp. 1946-1953
Author(s):  
Xin Gang Zhou ◽  
Fang Zhao
Keyword(s):  
Service Life ◽  
Initial Conditions ◽  
Error Function ◽  
Concrete Structures ◽  
Life Time ◽  
Chloride Penetration ◽  
Analytical Models ◽  
Chloride Ingress ◽  
Chloride Environment ◽  
Penetration Profile

According to investigations of apparent surface chloride contents and chloride penetration profile of concrete structures exposed to chloride environment, the influences of boundary and initial conditions, geometry parameters such as the geometry dimension and section shape, etc. were discussed. Based on the Fick’s second law of diffusion and different boundary and initial conditions, different analytical models to predict the chloride penetration profile in concrete structural members with different boundary and initial conditions were derived. Some calculations examples were made using those analytical models. Computational results show that the boundary and initial conditions have remarkable influences on chloride penetration profile and service life time of concrete structures. Using prevailing error-function solution model based on the semi-infinite assumption of chloride ingress, the prediction of service life time of concrete structures are over evaluated, in particular for the steel reinforcement in corner of the section. Some modify coefficients should be taken into consideration, concerning the influences of boundary and initial conditions.

Service Life Prediction of RC Member in Chloride Environments under Different Loading Level

2013 ◽  
Vol 438-439 ◽  
pp. 491-496
Author(s):  
Yun Fen Feng ◽  
Jin Xin Gong ◽  
Xiao Yan Yang ◽  
Qin Zhang
Keyword(s):  
Monte Carlo Simulation ◽  
Service Life ◽  
Life Prediction ◽  
Loading Condition ◽  
Model Error ◽  
Chloride Penetration ◽  
Reinforced Concrete Structures ◽  
Chloride Ingress ◽  
Probabilistic Framework ◽  
Flexural Member

Chloride ingress is a major factor affecting durability of reinforced concrete structures. In the present study, service life of a RC flexural member in chloride environments is predicted. First, model for service life is established considering model error and the coupling effects of loading condition and environmental factors on the chloride penetration. Then, service life is predicted in probabilistic framework of Monte Carlo simulation. The results show that the use of a lognormal distribution for the service life seems relevant; the service life shows a great scatterings.

scholarly journals Structural health assessment of reinforced concrete structure

2021 ◽  
Vol 1197 (1) ◽  
pp. 012019
Author(s):  
A A Raut ◽  
P D Pachpor ◽  
D P Mase
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Chloride Content ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Chloride Ingress ◽  
Commercial Building ◽  
Reinforced Concrete Structure ◽  
Chemical Test

Abstract There is a magnificent rise in repair, retrofitting and rehabilitation in construction industry in recent years. Concrete is a major used material in construction for various structures mainly because it deteriorates at a low rate. Concrete alone is durable but for structural application, Reinforced concrete is used. Reinforced concrete structures are not that durable because of number of reasons such as variation in construction methods, loading condition in service life and subsequent attack by environmental factors. The external symptoms range from cracking to spalling of concrete. In maximum field cases the main cause of deterioration are penetration of water and aggressive chemicals attack. Carbonation, Chloride ingress, leaching, sulphate attack, alkali-silica reaction are known responsible causes. Due to these reasons, during service life the structure deteriorates, and hence monitoring is required. If the condition of structure is below acceptable limit considering various parameters considered, the structure requires repair and retrofitting. For the study, we have considered G+3 Storey commercial building with a basement. Non-Destructive and Chemical Test. The Rebound hammer, Ultrasonic Pulse Velocity Test, Cover Meter Test, pH Test, Carbonation Test and Chloride Content Test are carried out to understand and analyze the current condition of the structure. The result computed from field and lab test were used as parameters for analyzing the structure in STAAD PRO Software. After assessing, the strengthening scheme for reinforced concrete structural components such as beams, columns and slab is discussed and suggested to increases the service life of structure.

Chloride Penetration Capacity in NPP Structures Caused by Crack

2011 ◽  
Vol 217-218 ◽  
pp. 830-834
Author(s):  
Ki Beom Kim ◽  
Do Gyeum Kim ◽  
Jang Hwa Lee
Keyword(s):  
Model Prediction ◽  
Laboratory Testing ◽  
Crack Width ◽  
Concrete Surface ◽  
Chloride Penetration ◽  
Chloride Profile ◽  
Definition Of ◽  
The Impact ◽  
Crack Widths

The speed of chloride penetration caused by cracking at the concrete surface is determined by the crack width. In this study, the impact of the cracks that can occur on the concrete surface (occurring from the contraction during concrete curing) on the chloride penetration speed was revealed through modeling. The accuracy of the established model was also verified through laboratory testing. The definition of the minimum crack width that affects the chloride penetration speed was established, based on testing and consideration of literature. The comparison of crack widths (20, 85, 125μm) based on the chloride profile and model prediction showed that there is virtually no chloride penetration at 20 μm, while the chloride penetration speed increased sharply at crack widths of 85 μm and 125 μm.

Study of the environment factor from Fick’s and electrical resistivity models by simulation of chloride diffusivity prediction

2020 ◽  
Vol 23 (10) ◽  
pp. 2097-2109
Author(s):  
Ronaldo A Medeiros-Junior ◽  
Diogo H Bem
Keyword(s):  
Electrical Resistivity ◽  
Service Life ◽  
Chloride Concentration ◽  
Chloride Content ◽  
Reinforced Concrete Structures ◽  
Type Ii ◽  
Total Chloride ◽  
Chloride Diffusivity ◽  
Resistivity Model ◽  
Environment Factor

The penetration of chlorides in concrete is the main reason for the beginning of corrosion in reinforced concrete structures exposed to a marine environment, reducing their service life. This article proposes correlations between the surface chloride content ( Cs) of Fick’s model and the ambient factor ( kCl) of a resistivity model. Literature data for three types of cement were used to simulate chloride diffusivity: (1) CEM I 52.5 R; (2) CEM II/A-P 42.5 R (with 6%–20% of pozzolans); and (3) CEM type II (with 12% of pozzolans and 8% of silica fume). Concretes containing these cements were analyzed for different environmental conditions: atmosphere zone, seawater immersion, and tidal/splash zones. The surface chloride contents were determined by a combination of Fick’s and resistivity models. In this article, it was noticed that the estimated Cs value varies with the exposure class from 0.484% to 0.644% (total chloride concentration by weight of cement). An equation has been proposed to correlate Cs with the ambient factor kCl of the resistivity model.

Durability of Concrete under Combined Exposure Conditions of Chlorides and Sulfates

2016 ◽  
Vol 711 ◽  
pp. 319-326 ◽  
Author(s):  
Kwang Jin In ◽  
Y.R. Jiang ◽  
Sang Hwa Jung ◽  
Myung Kue Lee ◽  
Sung Won Yoo ◽  
...  
Keyword(s):  
Concrete Structures ◽  
Construction Materials ◽  
Chloride Content ◽  
Chloride Penetration ◽  
Experimental Program ◽  
Chloride Ingress ◽  
Combined Exposure ◽  
Realistic Assessment ◽  
Set Up ◽  
Penetration Behavior

Concrete structures are generally subjected to serious deterioration under harsh environment, even though the concrete materials exhibit inherently higher durability than any other construction materials. The service life of concrete structures is directly affected by the durability performance under various conditions. In this regard, many studies have been conducted on the deterioration of concrete structures under various environmental conditions. However, previous studies were confined mostly to the deterioration of concrete structures under single deteriorating factor such as chloride ingress only or sulfate attack only, although real environment is actually a combination of such factors. The purpose of the present study is, therefore, to explore the effects of combined deterioration due to chlorides and sulfates in concrete structures. To this end, comprehensive experimental program has been set up to observe the chloride penetration behavior under combined deterioration conditions of chlorides and sulfates. The test results indicate that the chloride penetration is more pronounced for the case of combined attacks of chloride and sulfates than the case of single chloride attack. The surface chloride content is found to increase with time and this phenomenon is also more pronounced under the combined exposure of chlorides and sulfates. The present study may allow more realistic assessment of durability for such concrete structures which are subjected to combined attacks of chlorides and sulfates.

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