• 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 $kg/m^3$

• International Journal of Concrete Structures and Materials
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• v.6 no.3
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• pp.155-163
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• 2012

In order to predict the neutralization of concrete which is the reaction of carbonation dioxide from the outside and cement hydration product, such as calcium hydroxide and C-S-H, it was studied the numerical analysis method considering change of the pore structure and relative humidity during the neutralization reaction. Diffusion-reaction neutralization model was developed to predict the neutralization depth of concrete with coating finishing material. In order to build numerical analysis models considering outdoor environment and finishing materials, the adaption of proposed model was shown the results of existing outdoor exposure test results and accelerated carbonation test.

• Journal of the Korea Institute of Building Construction
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• v.13 no.2
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• pp.139-147
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• 2013

The purpose of this study was to investigate the durability performance of concrete that includes rice husk ash. Chloride diffusion coefficient obtained through a rapid chloride penetration test and depth of $CO_2$ penetration obtained through a rapid carbonation test were used to evaluate latent durability. Durability characteristics for rice husk ash replacement and age were determined. Through the experiment, it was found that when the replacement ratio of rice husk ash was increased from 0% to 10%, the compressive strength of concrete containing rice husk ash was similar to that of concrete containing silica fume. This shows that the durability performance of concrete containing rice husk is excellent compared to other concretes containing admixtures.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.77-82
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• 1996

The study was performed for the purpose of obtaining the fundamental data to improve the durability of concrete structures due to de-icing salts. To assume the degree of concrete deterioration, soluble chloride content in concrete, the depth of carbonation and compressive strength of core specimens were measured. The porgress of corrosion of concrete bridge was electrochemically monitored. The results show that the concrete structure was deteriorated and reinforced steel in concrete was corroded due to de-icing salts.

• 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 Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.373-380
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• 2023

This study investigated the carbonation of concrete brick cured in a CO₂ environment for the utilization of CO₂ captured in power plants. Concrete brick specimens were produced with electric arc furnace reducing slag (ERS) and electric arc furnace oxidizing slag (EOS), and cured for 3 days in a CO₂ chamber with a concentration of 20 % or in a constant temperature and humidity chamber. The weight change, compressive strength, flexural strength and carbonation depth of concrete bricks were measured. From the results, it was found that when subjected to CO₂ curing, CO₂ was absorbed at the level of 2.4 % of the weight of the specimen. The specimen incorporating ERS showed the highest carbonation depth, and satisfied KS F4004 standards for the concrete brick. Therefore, it is expected that the captured CO₂ can be utilized in the CO₂ curing process of concrete brick.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.128-138
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• 2015

Carbonation is one of the most critical deterioration phenomena to concrete structures exposed to high $CO_2$ concentration, sheltered from rain. Lots of researches have been performed on evaluation of carbonation depth and changes in hydrate compositions, however carbonation modeling is limitedly carried out due to complicated carbonic reaction and diffusion coefficient. This study presents a simplified carbonation model considering diffusion coefficient, solubility of $Ca(OH)_2$, porosity reduction, and carbonic reaction rate for low concentration. For verification, accelerated carbonation test with varying temperature and MIP (Mercury Intrusion Porosimetry) test are carried out, and carbonation depths are compared with those from the previous and the proposed model. Field data with low $CO_2$ concentration is compared with those from the proposed model. The proposed model shows very reasonable results like carbonation depth and consuming $Ca(OH)_2$ through reduced diffusion coefficient and porosity compared with the previous model.

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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• pp.73-78
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• 2009

Coal ash is a by-product of the combustion of pulverized coal, and much of this is dumped in landfills. The disposal of coal ash is one of the major issues for environmental problems. In this paper, the effects of the kinds and replacement ratio of coal ash on the durabilities of concrete mixtures are investigated. Fine aggregate was replaced with coal ash(fly ash and bottom ash) in five different ratios, of 0%, 10%, 20%, 35%, and 50% by volume. Test results indicated that the compressive strength increased with the increase in fly ash percentage. The loss of compressive strength of bottom ash concrete mixes after immersion in sulphuric acid solution was less than in the control mix(BA0). In addition, the carbonation depth of fly ash concrete mixes was lower than the control mix(FA0).

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.391-397
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• 2020

This study is to compare and analyze the strength, drying shrinkage and carbonation properties of lightweight aggregate mortar using recycling water as prewetting water and mixing water. The flow, compressive strength, split tensile strength, drying shrinkage and carbonation depth of lightweight aggregate mortar with recycling water were measured. As test results, the mortar flow was similar in all mixes regardless of the recycling water content. The compresseive strength of the RW5 mix with 5% recycling water as prewetting water and mixing water was the highest value, about 53.9 MPa after 28 days. In addition, the tensile strength of lightweight mortar was about 3.4 to 3.8 MPa, indicating 7 to 9% of the compressive strength value regardless of recycling water content. In the case of drying shrinkage, the RW2.5 mix using 2.5% recycling water showed the lowest shrinkage rate as about 0.107% at 56 days. The drying shrinkage of the plain mix without recycling water was relatively higher than the RW2.5 and RW5 mix. The RW5 mix showed lowest carbonation depth compared to other mixes. In this study, the RW5 lightweight aggregate mortar with 5% recycling water exhibits excellent compressive strength and carbonation resistance. Therefore, it is considered that if the recycling water, a by-product of the concrete industry, is properly used as prewetting water and mixing water of lightweight mortar and concrete, it will be possible to increase the recycling rate of the by-product and contribute to improve the property of lightweitht aggregate mortar and concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.669-674
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• 2003

The purpose of this study is to identify the diffusion coefficients of carbon dioxide for various concrete mixtures. The test results indicate that the diffusion coefficient increases with the increase of water-cement ratio. The diffusion coefficient decreases with the increase of relative humidity at the same water-cement ratio. The diffusion of carbon dioxide reached the steady-state within about five hours after exposure. It was found that the diffusion coefficient of cement paste is larger then that of concrete or mortar. The quantitative values of diffusivity of carbon dioxide in this study will allow more realistic assessment of carbonation depth in concrete structures.