• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.183-186
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• 2008

Carbonation is measured as Phenolphthalein Solution, it is possible to confirm the scope of alkali through acid and basic reaction. Then, Concrete Basic Reaction is decided according to alkali concentration depending on Potassium Hydroxide Now that Carbonation is gradually produced toward inner side from outer side, with time going by, it doesnt work, to some adequate depth, in as fast time as compulsory facilitating test. Thus, this research thesis made a comparative analysis on concrete phenomenal discoloration borderline following Phenolphthalein Solution, as part of a bid to measure Carbonation. Also, the thesis measured Concrete Alkali Concentration. The result showed that concrete coloring is classified into red and scarlet according to alkali concentration, and into borderline breakpoint of the speckle of scarlet and carbonation reaction. The higher chroma becomes with concrete decolorizing, the higher alkali concentration becomes.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.569-572
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• 2008

A series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges since 1995. In this study, based on the test results of the in-depth inspection, the identification of the extent of the chloride content and the incidence of the carbonation depth was conducted, and construction age and member type, environment condition were considered in this analysis. According to simple regression of the tested carbonation depth, the carbonation rate coefficient of the bridges in metropolises was estimated 5.41 and greater than 3.89 and 1.91 in case of marine condition and etc respectively. After measuring chloride content in concrete member, it was concluded that the chloride content of the bridges in marine condition was 4.7 times greater than the others. Especially, slabs had the most highly chloride content and it was estimated 0.709 $kg/m^3$

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.218-224
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• 1996

The purpose of this syudy is to set up a proper repair plan and to extend the remaining lifetime of them by measuring the remaining lifetime of reinforced concrete structures quantitatively. This method is based on the actual research on age deterioration, carbonation depth and covering depth of the reinforced concrete structures. Also, it measure the remaining lifetime through quantitatively defining the probability of steel corrosion by the damage of steel corrosion. By doing that, we proceed the proper repair plan after reviewing the possibility of lifetime extension.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.1 s.4
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• pp.143-152
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• 2002

The objectives of this paper were to obtain the fundamental data to analyze the causes of deterioration of 39 freeway concrete viaducts in Seoul metropolitan area. To investigate the degree of concrete deterioration, carbonation depth, soluble chloride concentration in hardened concrete and half-cell potentials of reinforcement were measured. The number of structures which carbonation depth penetrates to reinforcement was 25% of total. The model of carbonation .ate was induced to 3.92 $\sqrt{t}$, which was 5% faster than 3.727 $\sqrt{t}$ assumed 60% water-cement ratio, R=1 in that of kishitani. After measuring chloride concentration in concrete, it was concluded that about 24% of all readings on samples from concrete exceed the critical content to minimize the risk of chloride-induced corrosion. About 31% of the freeway viaducts structures had a value lower than -350mV(vs. CSE), so it could conclude that the excessive chloride concentration was the major cause of reinforcement corrosion. Among the structures which measured half-cell potentials less than -350mV, about 50% exceeds the maximum acceptable limit of chloride concentration.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.223-228
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• 1998

This study is to investigate on the remaining life of reinforced concrete apartment by using the probability of a reinforcing-steel corrosion and the carbonation tendency of domestic reinforced concrete apartments by using the statistic method. The results are as follow. ·To compare with the carbonation velocity of Kishitani's formula (x=3.727{{{{ SQRT { t} }}) when water-cement ratio is w=0.6, R=1, it is founded out that the carbonation velocity is slow a little in all area investigated and inland area, and fast a bit in coastal area. ·In the influencing factors in regard to the probability of reinforcing-steel corrosion, It seems that the influence of elapsed time is more effective than that of region. Therefore, it is necessary that it makes sure of the cover depth under apartment construction in recent so far as the durability is considered.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.727-730
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• 2005

The purpose of this study evaluates possibilities of waste phosphogypsum into concerts by steam curing admixture. The waste phosphogypsum is made use of 4 forms(Dehydrate, $\beta$-Hemihydrate, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. The penetration depth and compressive strength of cement mortar are investigated to evaluate the chloride ion and carbonation resistance. As a result, chloride ion and carbonation resistance of cement mortar admixed with waste phosphogypsum are more excellent than cement mortar contained OPC alone. The internal pores of cement mortar are decreased by using waste phosphogypsum, because the hydrates of ettringite which is denesified in structure is much formed in early ages at steam curing. These densified effect is concluded with improving the resistance to attack of cement mortar including waste phospogypsum.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.69-80
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• 2000

This paper presents the prediction of remaining service life of the concrete due to steel corrosion caused by the following three cases; carbonation, using sea sand and using deicing salts. The assessment of initiation period was generalized considering the existing perdiction models in the literature, corrosion experiment and field assessment. To evaluate the prediction equation of rust growth, the corrosion accelerating experiments was performed. The polarization resistance was measured by potentiostat and the conversion coefficient of polarzation resistance to corrosion rate was determined by the measurement of real mass loss. Chloride content, carbonation, cover depth, relative humidity, water-cement ratio(W/C), and the use of deicing salts were taken into account and the resulting prediction equation of rust growth was proposed on the basis of these properties. The proposed equation is to predict the rust growth during any specified period of time and be effective in particular for predicting service life of concrete in the case of using sea sand.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.315-322
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• 2012

Alkali-activated slag (AAS) is the most obvious alternative materials that can replace OPC. But, AAS industrial usage as a structural material should be evaluated for its durability. Carbonation resistance is one of the most important factors in durability evaluation. Test results for 18 slag-based mortars activated by sodium silicate and 6 OPC mortars were obtained in this study to verify the carbonation property. Main variables considered in the study were flow, compressive strength before and after carbonation, and carbonation depth. Mineralogical and micro-structural analysis of OPC and AAS specimens prior to and after carbonation was conducted using XRD, TGA, FTIR FE-SEM. Test results showed that CHS was major hydration products of AAS and, unlike OPC, no other hydration products were found. After carbonation, CSH of hydration product in AAS turned into an amorphous silica gel, and alumina compounds was not detected. From the analysis of the results, it was estimated that the micro-structures of CSH in AAS easily collapsed during carbonation. Also, the results showed that this collapse of chemical chain of CSH lowered the compressive strength of concrete after carbonation. By increasing the dosage of activators, carbonation resistance and compressive strength were effectively improved.

• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.119-126
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• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.730-737
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• 2014

In this study, chloride content of marine concrete bridge at the south coast in 5~34years was calculated based on the measured data and the validity of the proposed value was evaluated. Also, correlation of existence of salt injury prevention coating, chloride content, carbonation depth and the compressive strength of marine concrete bridges were derived and relationship of the four was evaluated. According to the research results, surface chloride content value in the tidal zone proposed form KCI 2009 and value in the splash zone and atmospheric zone proposed form Cheong et al.(2005) was the most valid. Also, salt injury prevention coating of marine concrete bridges had the outstanding effect of preventing chloride content penetration, carbonation depth and reduction in the compressive strength. Compressive strength of concrete was reduced by the increase of carbonation depth and chloride content.