• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.45-52
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• 2019

Steel corrosion due to carbonation in RC (Reinforced Concrete) structures easily occurs in urban cities with high CO₂ concentration. RC structures are always subjected to external loading with various boundary conditions. The induced stress level causes changes in diffusion of harmful ion like CO₂. In this work, a quantification of carbonation progress with stress level is carried out and carbonation prediction is derived through the relations. Determining the design parameters like cover depth, CO₂ diffusion coefficient, carbonatable materials, and exterior CO₂ concentration as random variables, service lifes under carbonation with design parameter's variation are obtained through MCS(Monte Carlo Simulation). Additionally the service life with different stress level is derived and the results are compared with those from deterministic method. Cover depth and cement hydrates are evaluated to be very effective to resist carbonation, and the proposed method which can consider the effect of stress on service life can be applied to maintenance priority determination.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.1-9
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• 2015

In this study, the objective of the study is to evaluate the effect of calcium carbonate powder, produced by the microbial reactions, on the strength of soft ground (sand). To analyze the cementation effects of calcium carbonate powder produced by microbial reactions on the strength of the sand, six different types of specimens (untreated, calcium carbonate, cement, carbonate+cement (1:9, 3:7, 5:5)) were made. The specimen were tested after curing (7 and 28 days). Uniaxial compressive strengths were measured on $D5cm{\times}H10cm$ specimens. Based on the test results, as both the weight ratio and the curing period increase, calcium carbonate, cement, and calcium carbonate+cement specimens showed an increase in the strength. In addition, compared with the strength of the specimen with cement, the strengths of the specimens with mixing ratios of 1:9, 3:7, and 5:5 (carbonate : cement) were found to be 93.5~95.8%, 825.%, 65.2~70.6%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.623-631
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• 2018

In this study, the degree of deterioration of concrete was investigated in the laboratory under conditions of carbonation and freeze-thaw cycling, which are the major causes of the deterioration of its performance. In this test, the carbonated concrete was subjected to combined freeze-thaw deterioration tests for up to 300 cycles, and its dynamic elastic modulus and compressive strength were measured. The evaluation of the effect of the water-binder ratio on normal concrete subjected to combined carbonization and freezing-thawing showed that its resistibility against such combined deterioration decreased more rapidly in the concrete with a water-binder ratio of 55 % compared with that having a water-binder ratio of 35 %. In the case where the concrete was blended with a mineral admixture consisting of fly ash and blast furnace slag at the same water-binder ratio, it showed an increase of its resistibility against combined deterioration.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.11
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• pp.597-606
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• 2015

This work investigates the carbonation of KOH-dissolved methanol and ethanol solution systems carried out for $CO_2$ fixation. Potassium methyl carbonate (PMC) and potassium ethyl carbonate (PEC) were synthesized during the reaction in each solution as the solid powder, and they were characterized in detail. The amount of $CO_2$ chemically absorbed to produce the PMC and PEC precipitates were calculated to be 97.90% and 99.58% of their theoretical values, respectively. In addition, a substantial amount of $CO_2$ was physically absorbed in the solution during the carbonation. PMC precipitates were consisted of the pure PMC and $KHCO_3$ with the weight ratio of 5:5, respectively. PEC precipitates were also mixture of the pure PEC and $KHCO_3$ with the weight ratio of 8:2, respectively. When these two precipitates were dissolved in excess water, methanol and ethanol were regenerated remaining solid $KHCO_3$ in the solutions. Therefore, the process has the potential to be one of the efficient options of CCS and CCU technologies.

• Current Research on Agriculture and Life Sciences
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• v.8
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• pp.83-88
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• 1990

This experiment was conducted to investigate the effect of $CO_2$ treatment on quality of strawberry during storage. Gas composition in polyethylene(P.E.) film bag during storage was changed markedly at early stage of storage and then kept at the level of 8-9% $CO_2$and 1-2% $O_2$. Weight loss and decay were restricted by $CO_2$ pretreatment and P.E. film packaging. Titratable acidity, PH and soluble solids were not changed greatly during storage. Firmness of flesh was increased by $CO_2$ treatment till 14 days of storage and decrease of a value reduced by $CO_2$ treatment and P.E.film packaging, too. Ascorbic acid contents were more high in not packed samples than packed untill 14 days of storage but after that those were more high in P.E.film packed and $CO_2$ treated samples.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.147-151
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• 2012

Carbon dioxide ($CO_2$) could be stored in the form of Ca and Mg compounds including alkaline earth metal by carbonation. The possibility of $CO_2$ storage was tested by using desulfurized ash from fluidized bed type boiler as raw material. Autoclave was used for maintaining the reaction pressure and temperature for the carbonation. The analysis of weight change rate, XRD, and TG/DTA proved that more than 15 % of carbonation rate was obtained under 10 $kgf/cm^2$ and $120^{\circ}C$-10 min.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.577-584
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• 2012

Carbonation resistance is one of the most influencing factors on durability of concrete. Alkali activated slag (AAS) is known to have weaker resistance for carbonation than OPC due to the low calcium contents. In this paper, the carbonation characteristic of AAS mortar which is related to the basicity (CaO/$SiO_2$) was investigated. In order to give the various basicity conditions, SM (source material) was blended with quicklime (CaO) and silicon dioxide ($SiO_2$) by adopting mechano-chemical treatment method. Experiments including flow test, compressive strength test, carbonation depth test, together with XRD, FTIR and TGA were employed to evaluate the effects of basicity of SM on the carbonation characteristics. The test results showed that the carbonation resistance effectively increased with the increase of the basicity of SM.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.116-121
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• 2012

The construction of underground structures such as box culverts for electric power transmission is increasing more and more, and the life extension of these structures is very important. Carbonation-induced corrosion in concrete may often occur in a high carbon dioxide environment. In this study, the risk of carbonation of two concrete box culverts in an urban area was evaluated by measuring the carbonation rate and concrete cover depth. Then, the carbonation-free service life at the depth of the steel was calculated, based on in situ information, by the Monte Carlo simulation. The service life of box culvert due to carbonation was estimated over 250 years via Monte Carlo simulation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.228-236
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• 2015

In this research, the influence of painting materials and applying timing on carbonation and chloride resistances of high volume SCMs concrete was evaluated. As a durability improving method, comparative tests were conducted with painting materials of ERCO (emulsified refined cooking oil), RCO (refined cooking oil), WR (water repellent agent), and ERCO + WR and with painting timings of right after demolding, and 28 days after the wet curing. From the experiment results, in the case of carbonation and chloride resistance, the carbonation depth and chloride penetration depth were decreased when the painting materials were applied in 28 days of wet curing. Additionally, for painting materials, with the order of ERCO, RCO, ERCO+WR, and WR, the carbonation and chloride penentration was delayed. Hence it is considered that ERCO shows the most favorable performance of resistance against carbonation and chloride penetration.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.70-76
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• 2012

For Analysis and evaluation of ALC carbonation, ALC with various specific gravity was fabricated and silicate and siloxane were used for spraying on ALC surface. Silicon oil of water repellent was added to ALC slurry. ALC carbonation related with specific gravity and carbonation degree was decreased with specific gravity. It was guessed that permeation of $CO_2$ gas reduced depend on compact structure of ALC. ALC which sprayed silicate and siloxane represented more excellent carbonation resistance than Ref. ALC. ALC added silicon oil represented most excellent carbonation resistance.