• Corrosion Science and Technology
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• v.8 no.2
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• pp.81-88
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• 2009

Chloride induced corrosion of steel reinforcement inside concrete is a major concern for concrete structures exposed to a marine environment. It is well known that transport of chloride ions in concrete occurs mainly through ionic/molecular diffusion, as a gradient of chloride concentration in the concrete pore solution is set. In the process of chloride transport, a portion of chlorides are bound in cement matrix then to be removed in the pore solution, and thus only the rest of chlorides which are not bound (i.e. free chlorides) leads the ingress of chlorides. However, since the measurement of free/bound chloride content is much susceptible to environmental conditions, chloride profiles expressed in total chlorides are evaluated to use in many studies In this study, the capacity of chloride binding in cement matrix was monitored for 150 days and then quantified using the Langmuir isotherm to determine the portions of free chlorides and bound chlorides at given total chlorides and the redistribution of free chlorides. Then, the diffusion of chloride ion in concrete was modeled by considering the binding capacity for the prediction of chloride profiles with the redistribution. The predicted chloride profiles were compared to those obtained from conventional model. It was found that the prediction of chloride profiles obtained by the model has shown slower diffusion than those by the conventional ones. This reflects that the prediction by total chloride may overestimate the ingress of chlorides by neglecting the redistribution of free chlorides caused by the binding capacity of cement matrix. From the evaluation, it is also shown that the service life prediction using the free chloride redistribution model needs different expression for the chloride threshold level which is expressed by the total chlorides in the conventional diffusion model.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.89-94
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• 2004

Most reinforcements in concrete are constructed by steel. Corrosion of reinforcement is the main cause of damage and early failure of reinforced concrete structures. The corrosion is mainly professed by the chloride ingress. In general, chloride in concrete can be discriminated by two components, total chloride and fire chloride. This paper provides a testing method on the coefficient of chloride diffusion in concrete and the relationship between total chloride and free chloride in concrete for the composition of predicting model on diffusion rate of chloride. In order to complete this predicting model, this study will use chloride penetration characteristic, diffusion coefficient and experiment of color change on silver nitrate solution. This predicting model is going to help that grasp special quality on salt content inclusion of concrete structure that is exposed in chloride environment. Accurate predicting model can be effectively used not only in selecting of repair time but also in preventing from various deteriorations.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.240-245
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• 1988

This study was prospectively planned to realize the reduction of calcium ion in serum along with the cardiopulmonary bypass[CPB], to find out the cause of the reduction, and to verify the justification of the classical methods of calcium replacement. Nine patients with various open heart surgeries by CPB in 1987 wee selected at random. Calcium chloride was added as follows:: For each unit of ACD blood transfusion, 600mg of calcium chloride was added. In case of massive transfusion, 600 mg of calcium chloride was injected every 2 or 3 units of transfusion. On occasions such as weaning from CPB, or following defibrillation, or hypotension, weak myocardial contractility of the heart, calcium chloride was needed in an amount of 10 mg / kg. In ICU, calcium chloride was limited to use in low serum level or in emergency use. Total calcium decreased early bypass and progressively increased above the preoperative value during late bypass and three hours thereafter, Ionized calcium increased during late bypass and three hours following. Total and ionized calcium depicted similar patterns of change during open heart surgery. Decrease of the calcium at the early bypass was thought from reduction of total protein and alkalosis during bypass. Meanwhile, increase of both calciums during the end of surgery was presumably attributable to addition of calcium chloride in priming solution, injections of calcium chloride in the process of termination of bypass. We conclude that enough calcium was replaced by the classical methods of calcium supplement.

• Corrosion Science and Technology
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• v.8 no.5
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• pp.171-176
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• 2009

The chloride threshold level (CTL) in mixed concrete containing, ordinary Portland cement (OPC), pulverized fuel ash (PFA) ground granulated blast furnace slag (GGBS), and silica fume (SF) is important for study on corrosion of reinforced concrete structures. The CTL is defined as a critical content of chloride at the steel depth of the steel which causes the breakdown of the passive film. The criterion of the CTL represented by total chloride content has been used due to convenience and practicality. In order to demonstrate a relationship between the CTL by total chloride content and the CTL by free chloride content, corrosion test and chloride binding capacity test were carried out. In corrosion test, Mortar specimens were cast using OPC, PFA, GGBS and SF, chlorides were admixed ranging 0.0, 0.2, 0.4, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder. All specimens were cured 28 days, and then the corrosion rate was measured by the Tafel's extrapolation method. In chloride binding capacity, paste specimens were casting using OPC, PFA, GGBS and SF, chlorides were admixed ranging 0.1, 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binders. At 28days, solution mixed with the powder of ground specimens was used to measure binding capacity. All specimens of both experiments were wrapped in polythene film to avoid leaching out of chloride and hydroxyl ions. As a result, the CTL by total chloride content ranged from 0.36-1.44% by weight of binders and the CTL by free chloride content ranged from 0.14-0.96%. Accordingly, the difference was ranging, from 0.22 to 0.48% by weight of binder. The order of difference for binder is OPC > 10% SF > 30% PFA > 60% GGBS.

• Computers and Concrete
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• v.3 no.6
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• pp.401-422
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• 2006

A multi-species model based on the Nernst-Planck equation has been developed by using a finite volume method. The model makes it possible to simulate transport due to an electrical field or by diffusion and to predict chloride penetration through water saturated concrete. The model is used in this paper to assess and analyse chloride diffusion coefficients and chloride binding isotherms. The experimental assessment of the effective chloride diffusion coefficient consists in measuring the chloride penetration depth by using a colorimetric method. The effective diffusion coefficient determined numerically allows to correctly reproduce the chloride penetration depth measured experimentally. Then, a new approach for the determination of chloride binding, based on non-steady state diffusion tests, is proposed. The binding isotherm is identified by a numerical inverse method from a single experimental total chloride concentration profile obtained at a given exposure time and from Freundlich's formula. In order to determine the initial pore solution composition (required as initial conditions for the model), the method of Taylor that describes the release of alkalis from cement and alkali sorption by the hydration products is used here. Finally, with these input data, prediction of total and water-soluble chloride concentration profiles has been performed. The method is validated by comparing the results of numerical simulations to experimental results obtained on various types of concretes and under different exposure conditions.

• Journal of the East Asian Society of Dietary Life
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• v.4 no.3
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• pp.123-133
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• 1994

The ground pork patties were made to add two level of sodium chloride(2.5%, 3.0%) and replace part(50%) of the sodium chloride(NaCl) with either potassium chloride(KCl), magnesium chloride(MgCl2) or calcium chloride(CaCl2). These samples were analyzed for their chemical composition, VBN value, TBA value, microbial counts, and cooking loss. The ground pork with NaCl 2.5% was more desirable in saltness than the ground pork with NaCl 3.0%. Replacing 50% of the sodium chloride with potassium chloride was more desirable to flavor, color, juiciness, and overall acceptability than replacing 50% of the sodium chloride with either magnesium chloride or calcium chloride. The ground pork with NaCl 2.5% or NaCl 1.25% ＋KCI 1.60% had higher pH value than the ground pork with NaCl 1.25% ＋MgCl2 0.67% or NaCl 1.25% ＋CaCl2 0.79%. The ground pork with the ground pork with NaCl 2.5% had lower VBN value than the ground pork with either NaCl 1.25%＋KCI 1.60%, NaCl 1.25% ＋ MgCl2 0.67%, or NaCl 1.25% ＋CaCl2 0.79%. The ground pork with NaCl 1.25% ＋ CaCl2 0.67% had higher increase in total colony count than the ground pork with NaCl 2.5% or NaCl 1.25% ＋ CaCl2 0.79%. Cooking loss of ground pork with NaCl 2.5% was lowest and cooking loss of ground pork with NaCl 1.25% ＋ KCl 1.60% was highest. Potassium chloride would not be a substitute for sodium chloride in cooking loss and total colony count but potassium chloride more closely approximated the sensory properties of sodium chloride than either magnesium chloride or calcium chloride.

• Advances in concrete construction
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• v.12 no.6
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• pp.451-459
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• 2021

The mechanical behaviors and chloride resistance performance of fiber reinforced cementitious composites (FRCC) with hybrid polyethylene (PE) and steel fiber (in total 2% by volume) were investigated. Based on micro-mechanics and fracture mechanics, the reason why the tensile strain capacity of FRCC changed obviously was obtained. Besides, the effects of the total surface area of fiber in FRCC on compressive strength and chloride content were clarified. It is found that the improvement of the tensile strain capacity of FRCC with hybrid fiber is attributed to the growth of strain-hardening performance index (the ratio of complementary energy to crack tip toughness). As the total surface area of fiber related with the interfacial transition zone (ITZ) between fiber and matrix increases, compressive strength decreases obviously. Since the total surface area of fiber is small, the chloride resistance performance of FRCC with hybrid PE and steel fiber is better than that of FRCC containing only PE fiber.

• Computers and Concrete
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• v.13 no.6
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• pp.695-707
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• 2014

This study investigated the chloride binding isotherms of various cement types, especially the contributions of C-S-H and AFm hydrates to the chloride binding isotherms were determined. Ordinary Portland cement (OPC), Modified cement (MC), Rapid-hardening Portland cement (RHC) and Low-heat Portland cement (LHC) were used. The total chloride contents and free chloride contents were analyzed by ASTM. The contents of C-S-H, AFm hydrates and Friedel's salt were determined by X-ray diffraction Rietveld (XRD Rietveld) analysis. The results showed that OPC had the highest chloride binding capacity, and, LHC had the lowest binding capacity of chloride ions. MC and RHC had very similar capacities to bind chloride ions. Experimental equations which distinguish the chemically bound chloride and physically bound chloride were formulated to determine amounts of the bound chloride basing on chloride binding capacity of hydrates.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.2
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• pp.71-79
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• 2003

The estimation functions were proposed for calculating diffusion coefficient, chloride binding, and evaporable water. The program estimating chloride ion penetration was developed on the basis of these functions and the effects of humidity, curing temperature, water-cement ratio, and $C_3$A on chloride penetration were analyzed. The relative humidity increases the depth of chloride ion penetration and the trend becomes greater with aging. On the contrary, the influence of curing temperature on chloride ion penetration decreases with aging. By the way, the rise of $C_3$A in cement increases total chloride concentration on the surface as the bound chloride concentration increases but it decreases total chloride concentration on the inner part as the diffusion velocity of free chloride decreases. The fall of water-cement ratio decreases the chloride penetration depth rapidly. Therefore, the reduction of water-cement ratio may be the most effective method for reducing of the steel corrosion by chloride penetration.

• Journal of Sericultural and Entomological Science
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• v.41 no.3
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• pp.211-215
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• 1999

The pure-separation of calcium chloride-treated fibroin hydrolysates could be carried out using gel filtration chromatography. Also, the effect of its enzymatic hydrolysis was investigated in order to find out the enhancement of their functionality. The average molecular weight(Mw), solubility and free amino acid compositions of three hydrolysates samples (calcium chloride, calcium chloride-flavourzyme and calcium chloride-thermoase)were measured to compare their characteristics. The molecular weight of calcium chloride hydrolysate was about Mw 46,800 and it can be reduced to Mw 12,500 and 1,070 upon the enzymatic hydrolysis by flavourzyme and thermoase, repectively. A solubility of calcium chloride-treated samples shows about 60% while calcium chloride/enzyme-treated samples are perfectly soluble (100% solubility). The total amino acid composition of calcium chloride enzymatic hydrolysates are much higher than that of calcium chloride hydrolysate.