• Computers and Concrete
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• 제10권3호
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• pp.219-229
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• 2012

Carbonation is a widespread degradation of concrete and may be coupled with more severe degradations. An experimental investigation was carried out to study the effect of carbonation on chloride ion diffusion of concrete. The characteristic of concrete after carbonation was measured, such as carbonation depth, strength and pore structure. Results indicated that carbonation depth has a good linear relation with square root of carbonate time, and carbonation can improve compressive strength, but lower flexural strength. Results about pore structure of concrete before and after carbonation have shown that carbonation could cause a redistribution of the pore sizes and increase the proportion of small pores. It also can decrease porosities, most probable pore size and average pore diameters. Chloride ion diffusion of concrete after carbonation was studied through natural diffusion method and steady state migration testing method respectively. It is supposed that the chloride ion concentration of carbonation region is higher than that of the sound region because of the separation of fixed salts, and chloride ion diffusion coefficient was increased due to carbonation action evidently.

• 한국구조물진단유지관리공학회 논문집
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• 제18권5호
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• pp.27-33
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• 2014

전기저항은 콘크리트의 내구성을 판단하기 위하여 빠르고 간단히 측정하여 활용될 수 있으나, 탄산화가 진행되면 콘크리트의 미세구조가 크게 변화하기 때문에 측정의 오차를 초래한다. 본 연구의 목적은 콘크리트의 탄산화가 전기저항에 미치는 영향을 분석하고 정량화 하는데 있다. 다양한 물시멘트비 조건에서 시험편을 제조하여 330일동안 탄산화 촉진을 시키면서 전기저항의 변화율을 고찰하였다. 탄산화된 콘크리트에서 전기저항 측정치가 높은 것으로 나타났으며, 이러한 경향은 탄산화가 진행됨에 따라 더욱 뚜렷한 경향을 보였다. 전기저항과 탄산화깊이와의 상관관계를 도출하였으며, 기중 상태 대비 탄산화된 콘크리트의 전기저항 비율은 일정한 탄산화깊이까지는 급격히 낮아지는 경향을 보였으나, 포화상태 대비 탄산화된 콘크리트의 전기비율은 탄산화 깊이와 선형관계를 보였다. 본 연구를 토대로 탄산화로 인하여 전기저항치의 측정오차를 보정할 수 있는데 실질적으로 활용될 수 있을 것으로 기대된다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권4호
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• pp.163-171
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• 1999

In this study, we executed fundamental experiment to investigate properties of accelerated carbonation with changing chloride content of concrete used sea sand in order to examine durability. So we obtained the results of following properties of mechanics, durability, concrete with sea sand, determined concrete w/C 30%, 40%, 50%, and fine aggregate 40% and changing containing chloride 0, 0.3, 0.6, $0.9kg/m^3$ by the experiment of accelerated neutralization. The results of this study as follows: 1) As result of changing chloride content of concrete used sea sand augmented in stages $0.3kg/m^3$, accelerated carbonation was increased as increment chloride content. The increment depth was decreased as it went long term age. It was shown the chloride content effected increment of carbonation depth in concrete 2) As a result of changing W/C of concrete used sea sand augmented in stages 10% at a time from 30% to 50%, accelerated carbonation depth of concrete was increased as W/C ratio. 3) As the carbonation concrete used sea sand, compressive strength between 8 weeks and accelerated carbonation depth of 1 weeks, 2 weeks, 4 weeks, 8 weeks was inversion proportion.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.197-198
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• 2021

The temperature and humidity inside concrete affects the depth of carbonation. In this study, the temperature and humidity inside concrete were predicted by the numerical method under the boundary conditions of ambient temperature, humidity, solar radiation, and wind. Using the results of the thermal humidity analysis, diffusion of carbon dioxide and the reaction of cement hydration products were calculated for carbonation depth.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.71-72
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• 2012

The purpose of this study is to evaluate the depth of carbonation considering the relative humidity in concrete using the FEM model. The difference of relative humidity in concrete has not been considered in calculating the carbonation depth in analytic model. That reason can make the over estimation in expectation of RC structure durability. The temperature and R.H. expectation model and the carbonation depth expectation model are development in past author's studies. The two models are coupled in this study. The fact that there is the difference between actual environment and acceleration test is revealed from FEM numerical analysis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.90-93
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• 2003

The most common deteriorating processes of concrete structures in the world-wide are carbonation and chloride ion. In this paper, chloride profiles of carbonated concrete is predicted to considering two layer composite model, which is based on Fick's 2nd law. From the experimental result on combined deterioration of chloride and carbonation, it was examined that high chloride concentration was built up to 3-5㎜ over depth from carbonation depth. The analytical modeling of chloride diffusion, which was based on the Fick's 2nd law of diffusion, was suggested to depict the relative influence of the carbonation depth.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.30-31
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• 2015

Usually, carbonation of concrete causes pH reduction and corrosion of steel, it leads to decrease of durability. However, CaCO₃, as results of reaction with hydrates products and CO₂, can contribute to improvement of compressive strength. Based on this theory, using carbonation depth, the researches about CO₂ absorption of plain concrete and concrete containing CO₂ reactive materials has been performed. But, the researches has limitation about using one material, therefore, for this study, considering various CO₂ reactive materials, experiment has been proceeded. With water to binder ratio 50%, after initial curing for 2days, accelerated carbonation was performed for 28days, and carbonation depth and compressive strength were measured. As results of carbonation depth, specimen containing desulfurized slag, zeolite showed the highest CO₂ absorption, in case of compressive strength, specimens with MgO were indicated as highest compressive strength.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.55-64
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• 2017

The paper concerns concrete carbonation, the phenomena that occurs in every type of climate, especially in urban-industrial areas. In European Standards, including Eurocode (EC) for concrete structures the demanded durability of construction located in the conditions of the carbonation threat is mainly assured by the selection of suitable thickness of reinforcement cover. According to EC0 and EC2, the thickness of the cover in the particular class of exposure depends on the structural class/category and concrete compressive strength class which is determined by cement content and water-cement ratio (thus the quantitative composition) but it is not differentiated for various cements, nor additives (i.e., qualitative composition), nor technological types of concrete. As a consequence the selected thickness of concrete cover is in fact a far estimation - sometimes too exaggerated (too safe or too risky). The paper presents the elaborated "self-terminated carbonation model" that includes abovementioned factors and enables to indicate the maximal possible depth of carbonation. This is possible because presented model is a hyperbolic function of carbonation depth in time (the other models published in the literature use the parabolic function that theoretically assume the infinite increase of carbonation depth value). The paper discusses the presented model in comparison to other models published in the literature, moreover it contains the algorithm of concrete cover design with use of the model as well as an example of calculation of the cover thickness.

• 한국컴퓨터산업학회논문지
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• 제9권4호
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• pp.143-148
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• 2008

콘크리트의 탄산화를 진행시키는 가장 주요한 영향인자는 대기 중의 농도이다. 본 연구에서는 대기 중의 이산화탄소 농도에 따른 탄산화 진행 정도를 개발한 프로그램을 통하여 해석적으로 접근하였다. 또한 해석 프로그램을 통하여 이산화탄소 농도에 따른 내구수명을 산정하였다. 이산화탄소 표면농도가 0.1%인 경우도 탄산화 깊이가 50mm 정도로 나타났다. 콘크리트의 피복두께를 40mm를 유지한다면 이산화탄소 표면농도가 0.1%일 때 콘크리트의 내구수명은 67년으로 검토되었다.

• 한국해안·해양공학회논문집
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• 제22권4호
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• pp.272-278
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• 2010

탄산화에 미치는 온도의 영향에 대해서는 매우 상반된 2가지의 주장이 존재하는데, 온도증가는 탄산화 반응을 가속화시켜 탄산화 깊이를 증가시킨다는 주장과 탄산화 반응을 일으키는 최적의 온도조건이 있으며, 탄산화 깊이는 이러한 최적의 온도조건에서 가장 큰 값을 가진다는 주장이다. 일반적으로 탄산화는 시멘트 수화물 중 수산화칼슘과 이산화탄소의 화학반응으로 생성되는 것으로 알려져 왔고 많은 탄산화 연구들도 이에 집중되어 왔다. 그러나, 최근의 몇몇 연구에서는 수산화칼슘을 제외한 다른 시멘트 수화물도 탄산화 반응이 일어난다는 결과를 발표하고 있다. 본 연구에서는 온도의 탄산화에 미치는 영향을 파악하기 위하여 탄산화 온도에 따른 탄산화 깊이와 탄산화 반응물과 생성물에 대한 실험을 수행한다. 또한, 실험결과의 분석을 통하여 수산화칼슘이외의 수화생성물이 탄산화에 미치는 영향을 파악하고자 하였다. 탄산화 깊이는 페놀프탈레인 용액법으로 측정하였고, 탄산화 전후의 반응물과 생성물은 열중량분석기(Thermogravimetric analyzer)를 이용하여 측정하였다. 탄산화 온도가 $20^{\circ}C$에서 $30^{\circ}C$로 증가하면 탄산화 깊이가 크게 증가하였지만 온도가 $30^{\circ}C$에서 $40^{\circ}C$로 증가하면 탄산화 깊이가 거의 증가하지 않았다. 이것은 탄산화 반응에 대한 최적의 온도조건이 존재할 수 있다는 증거일 수 있다. 페놀프탈레인 용액법에 의한 탄산화 깊이는 수산화칼슘과 탄산칼슘의 양이 변화하여 교차하는 영역에 존재한다. 탄산화 온도 $30^{\circ}C$와 $40^{\circ}C$에서의 수산화칼슘 이외의 시멘트 수화물에 의해 생성된 탄산칼슘양은 온도가 증가하면 감소함을 관찰할 수 있었다.