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.

The Expression of Surface Chloride Concentration in Ecological Concrete and Service Life Prediction

2011 ◽  
Vol 368-373 ◽  
pp. 2204-2210 ◽  
Author(s):  
Si Feng Liu
Keyword(s):  
Fly Ash ◽  
Service Life ◽  
Life Prediction ◽  
Chloride Concentration ◽  
Total Chloride ◽  
One Dimensional ◽  
Dimensional Diffusion ◽  
Diffusion Depth ◽  
Chloride Concentrations

The total chloride concentrations of concrete with 0.51 of water to cementitous from three contents of Fly ash, GGBS, two kinds of corrosion solution for one dimensional diffusion at different diffusion depth and time were measured by chemical titration. The influence of Fly ash and GGBS content on total chloride concentration and the surface chloride concentration were analyzed. The expressions of the surface chloride concentration were discussed in terms of the experimental results related with content of Fly ash, GGBS and solution. The numerical analysis results indicated that the expression of the surface chloride concentration has a significant impact on the long-term service life of concrete in chloride environments.

Study on Corrosion Resistance of 2205 Stainless Steel Reinforcement in Simulated Concrete Pore Solution

2013 ◽  
Vol 838-841 ◽  
pp. 119-122
Author(s):  
Long Chen ◽  
Yu Qu ◽  
Yan Bing Tang ◽  
Xiang Fang
Keyword(s):  
Stainless Steel ◽  
Reinforced Concrete ◽  
Passive Film ◽  
Pore Solution ◽  
Concrete Structures ◽  
Chloride Concentration ◽  
Chloride Content ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structures ◽  
Current Time

The steel rebar inside reinforced concrete structures is susceptible to corrosion when the chloride content at the surface of the steel exceeding the critical chloride concentration. Stainless steel reinforcements have proved to be the most reliable methods to assure the durability of reinforced concrete structures in marine environment for the compact passive films forming on its surfaces and higher critical chloride concentration. In the present work, the compactness of passive film on 2205 stainless steel in simulated concrete pore solution (SPS) is compared with carbon steel (Q235). the critical chloride concentration of Q235 and 2205 stainless steel reinforcement are discussed. Results indicate the slope(k) of double-log plot of current time for 2205 stainless steel is higher than Q235 , thekvalue is related with the compactness of passive film, the critical chloride concentration of 2205 stainless steel is much higher than Q235 steel in SPS.

scholarly journals ALTERNATE APPROACH FOR LIMITING CHLORIDES IN CONCRETE MIX

2020 ◽  
Vol 9 (6) ◽  
pp. 72-76
Keyword(s):  
Reinforced Concrete ◽  
Nuclear Power ◽  
Concrete Structures ◽  
Coastal Region ◽  
Chloride Content ◽  
Water Soluble ◽  
Reinforced Concrete Structures ◽  
Time Saving ◽  
Total Chloride ◽  
Concrete Mix

Chloride is considered as an important parameter in concrete as it accelerates corrosion of reinforcement, which is one of the main causes of deterioration of reinforced concrete structures. Different Codes describe different limits for either one or more constituents of concrete. The Indian Standard 269 – 2013 “Ordinary Portland cement, 33 grade – fifth revision” prescribes a limit of total chloride content in cement used in prestressed concrete structures and long span reinforced concrete structures, while Indian Standard 456- 2000 ”Code of practice for plain & reinforced concrete – fourth revision” imposes a limit of total amount of chloride (as Cl) in the concrete at the time of placing, without any mention about the methodology of determining the total amount of chloride (acid soluble or water soluble). Further, Italian standard prescribes limit for aggregates. American Concrete Institute (ACI) publication has given a new direction to the study of chloride induced corrosion by taking limit of water soluble chloride in concrete mix as the criteria for evaluation of risk of corrosion. This novel & improved approach which avoids confusion in interpreting specifications and results, was applied to some concrete ingredients samples received from a Nuclear Power Project of coastal region of India. The alternate approach suggested in this Paper does away with te laborious process of casting cubes and and waiting for twenty eight days before test could be carried out. Where different quarries of coarse and fine aggregates have been identified, the alternate approach can at the initial stage itself rule out of the possibility of casting cubes of different grades of concrete mixes, resulting in time saving and economy.

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 Chloride Binding Capacity and Its Effect on the Microstructure of Mortar Made with Marine Sand

2021 ◽  
Vol 13 (8) ◽  
pp. 4169
Author(s):  
Congtao Sun ◽  
Ming Sun ◽  
Tao Tao ◽  
Feng Qu ◽  
Gongxun Wang ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Chloride Content ◽  
Chloride Ions ◽  
Fine Aggregate ◽  
Chloride Binding ◽  
River Sand ◽  
Total Chloride ◽  
Curing Period ◽  
Marine Sand ◽  
Bound Chloride

Chloride binding capacity and its effect on the microstructure of mortar made with marine sand (MS), washed MS (WMS) and river sand (RS) were investigated in this study. The chloride contents, hydration products, micromorphology and pore structures of mortars were analyzed. The results showed that there was a diffusion trend for chloride ions from the surface of fine aggregate to cement hydrated products. During the whole curing period, the free chloride content in the mortars made by MS and WMS increased firstly, then decreased and stabilized finally with time. However, the total chloride content of three types of mortar hardly changed. The bound chloride content in the mortars made by MS and WMS slightly increased with time, and the bound chloride content included the MS, the WMS and the RS arranged from high to low. C3A·CaCl2·10H2O (Friedel’s salt) was formed at the early age and existed throughout the curing period. Moreover, the volume of fine capillary pore with a size of 10–100 nm increased in the MS and WMS mortar.

TURBIDITY OF SUSPENSIONS AND MORPHOLOGY OF RED HALOPHILIC BACTERIA AS INFLUENCED BY SODIUM CHLORIDE CONCENTRATION

1960 ◽  
Vol 6 (5) ◽  
pp. 535-543 ◽  
Author(s):  
Dinah Abram ◽  
N. E. Gibbons
Keyword(s):  
Sodium Chloride ◽  
Salt Concentration ◽  
Morphological Changes ◽  
Halophilic Bacteria ◽  
Chloride Concentration ◽  
Chloride Content ◽  
Wall Structure ◽  
Abrupt Decrease ◽  
High Sodium ◽  
Rigid Cell Wall

The optical densities of suspensions of cells of Halobacterium cutirubrum, H. halobium, or H. salinarium, grown in media containing 4.5 M sodium chloride, increase as the salt concentration of the suspending medium decreases, until a maximum is reached at about 2 M; below this concentration there is an abrupt decrease in optical density. The cells are rod shaped in 4.5 M salt and change, as the salt concentration decreases, through irregular transition forms to spheres; equal numbers of transition forms and spheres are present at the point of maximum turbidity, while spheres predominate at lower salt concentrations. Cells suspended in 3.0 M salt, although slightly swollen, are viable, but viability decreases rapidly with the more drastic changes in morphology at lower salt concentrations. Cells grown in the presence of iron are more resistant to morphological changes but follow the same sequence. Cells "fixed" with formaldehyde, at any point in the sequence, act as osmometers and do not rupture in distilled water although their volume increases 10–14 times. The results indicate that the red halophilic rods require a high sodium chloride content in their growth or suspending medium to maintain a rigid cell wall structure.

Physical and Chemical Deterioration of Reinforced Concrete Reefs in Tongyeong Reefs Coastal Waters, Korea

2008 ◽  
Vol 42 (3) ◽  
pp. 110-118 ◽  
Author(s):  
H. S. Kim ◽  
C. G. Kim ◽  
W. B. Na ◽  
J. Woo ◽  
J. K. Kim
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Dissolved Oxygen ◽  
Extreme Event ◽  
Chemical Properties ◽  
Chloride Concentration ◽  
Concrete Cover ◽  
Marine Habitat ◽  
Seawater Salinity ◽  
Physical And Chemical

As part of a marine habitat enhancement project, the physical and chemical deterioration of reinforced concrete reefs that were fully immersed in Tongyeong waters of Korea was investigated. For the investigation, marine environmental factors such as seawater, salinity, pH, dissolved oxygen, sea-bottom materials, and water depth of the targeted sites were surveyed from 1997 to 2001. Then, four reinforced concrete reefs from four different sites were recovered and tested by using various destructive and nondestructive methods. Based on the observations and test results, it was seen that the reinforced concrete reefs have sound physical and chemical properties, except for chloride concentration and its associated factors. However, because of the lack of dissolved oxygen in the targeted seawaters and its continuous supply, it is concluded that the originally designed service life will be achieved, and in fact the concrete reefs will have an even longer service life than expected. By considering an extreme event such as impact loading under installation and construction, a new minimum concrete cover depth of 40 mm is introduced into practice.

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