• Advances in concrete construction
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• 제2권3호
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• pp.163-176
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• 2014

Essentially, when electrical current flows easily in concrete that has large pores filled with highly connective pore water, this is an indication of a low resistivity concrete. In concrete, the flow of current between anodic and cathodic sites on a steel reinforcing bar surface is regulated by the concrete electrical resistance. Therefore, deterioration of any existing reinforced concrete structure due to corrosion of reinforcement steel bar is governed, to some extent, by resistivity of concrete. Resistivity of concrete can be improved by using SCMs and thus increases the concrete electrical resistance and the ability of concrete to resist chloride ingress and/or oxygen penetration resulting in prolonging the onset of corrosion. After depassivation it may slow down the corrosion rate of the steel bar. This indicates the need for further study of the effect of electric arc furnace dust (EAFD) addition on the concrete resistivity. In this study, concrete specimens rather than mortars were cast with different additions of EAFD to verify the electrochemical results obtained and to try to understand the role of EAFD addition in influencing the corrosion behaviour of reinforcing steel bar embedded in concrete and its relation to the resistivity of concrete. The results of these investigations indicated that the corrosion resistance of steel bars embedded in concrete containing EAFD was improved, which may link to the high resistivity found in EAFD-concrete. In this paper, potential measurements, corrosion rates, gravimetric corrosion weight results and resistivity measurements will be presented and their relationships will also be discussed in details.

• Computers and Concrete
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• 제15권3호
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• pp.461-471
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• 2015

The permeability is the most direct indicator to reflect the durability of concrete, and the testing methods based on external electric field can be used to evaluate concrete permeability rapidly. This study aims to use an experiment method to accurately predict the permeability of concrete box beam during service. The ion migration experiments and concrete surface resistivity are measured to evaluate permeability of five concrete box beams, and the relations between these results in service concrete and electric flux after 6 hours by ASTM C1202 in the laboratory are analyzed. The chloride diffusion coefficient of concrete, concrete surface resistivity and concrete 6 hours charge have good correlation relationship, which denote that the chloride diffusion coefficient and the surface resistivity of concrete are effective for evaluating the durability of concrete structures. The chloride diffusion coefficient of concrete is directly evaluated permeability of concrete box beam in service and may be used to predict the service life, which is fit to engineering applications and the concrete box beam is non-destructive. The concrete surface resistivity is easier available than the chloride diffusion coefficient, but it is directly not used to calculate the service life. Therefore the mathematical relation of the concrete surface resistivity and the concrete chloride diffusion coefficient need to be found, which the service life of reinforced concrete is obtained by the concrete surface resistivity.

• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.119-132
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• 2015

Electrical resistivity is an important physical property of portland cement concrete which is directly related to chloride induced corrosion process. This study examined the electrical surface resistivity (SR) and bulk electrical resistivity (BR) of concrete cylinders for various binary and ternary based high-performance concrete (HPC) mixtures from 7 to 161 days. Two different types of instruments were utilized for this investigation and they were 4 point Wenner probe meter for SR and Merlin conductivity tester for bulk resistivity measurements. Chronological development of electrical resistivity as well as correlation between two types of resistivity on several days was established for all concrete mixtures. The ratio of experimental surface resistance to bulk resistance and corresponding resistivity was computed and compared with theoretical values. Results depicted that bulk and SR are well correlated for different groups of HPC mixtures and these mixtures have attained higher range of electrical resistivity for both types of measurements. In addition, this study presents distribution of surface and bulk resistivity in different permeability classes as proposed by Florida Department of Transportation (FDOT) specification from 7 to 161 days. Furthermore, electrical resistivity data for several HPC mixtures and testing procedure provide multiple promising options for long lasting bridge decks against chloride induced corrosion due to its ease of implementation, repeatability, non-destructive nature, and low cost.

• 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.

• Computers and Concrete
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• 제19권5호
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• pp.467-475
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• 2017

The purpose of this study is to establish a prediction model for the electrical resistivity ($E_r$) of self-consolidating concrete by using waste LCD (liquid crystal display) glass as part of the fine aggregate and then, to analyze the results obtained from a series of laboratory tests. A hyperbolic function is used to perform nonlinear multivariate regression analysis of the electrical resistivity prediction model, with parameters such as water-binder ratio (w/b), curing age (t) and waste glass content (G). Furthermore, the relationship of compressive strength and electrical resistivity of waste LCD glass concrete is also found by a logarithm function, while compressive strength is evaluated by the electrical resistivity of non-destructive testing (NDT). According to relative regression analysis, the electrical resistivity and compressive strength prediction models are developed, and the results show that a good agreement is obtained using the proposed prediction models. From the comparison between the predicted analysis values and test results, the MAPE value of electrical resistivity is 17.0-18.2% and less than 20%, the MAPE value of compressive strength evaluated by $E_r$ is 5.9-10.6% and nearly less than 10%. Therefore, the prediction models established in this study have good predictive ability for electrical resistivity and compressive strength of waste LCD glass concrete. However, further study is needed in regard to applying the proposed prediction models to other ranges of mixture parameters.

• 한국구조물진단유지관리공학회 논문집
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• 제18권6호
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• pp.90-96
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• 2014

콘크리트의 전기저항은 철근부식 개시 이전인 잠복기와 철근부식되는 진전기 두과정과 유관된다. 염소이온에 노출된 콘크리트 구조물의 전기저항은 초기 부식율의 위험도를 표현할 수 있는데, 낮은 전기저항은 빠른 염소이온 침투와 높은 부식속도를 의미하기 때문이다. 콘크리트의 전기저항은 인가된 전압과 전류간의 비율인 전기저항으로 표현된다. 이전의 연구에 의하면 콘크리트의 전기저항은 콘크리트내 수분량, 미세구조 및 탄산화 등에 크게 의존하였다. 습윤량과 전기저항의 관계를 다룬 연구가 적지만 존재하는 반면, 염소이온이 전기저항에 미치는 연구를 행한 연구는 매우 드물다. 본 연구의 목적은 염소이온이 콘크리트의 전기저항에 미치는 영향을 고찰하는 것이다. 실험결과에 의하면 염소이온량은 전기저항을 떨어뜨리는 것으로 나타났으며 이는 선형의 관계가 성립되었다. 초기 양생 50일 이전까지 전기저항의 감소추세는 뚜렷하였으며, 이후로는 염소이온량과 상관없이 일정하였다. 결과적으로 본 연구는 염소이온량을 함유한 콘크리트의 전기저항을 표현하는데 결정적인 방법을 제안하였다.

• 한국도로학회논문집
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• 제19권3호
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• pp.57-63
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• 2017

PURPOSES : The pole electrode method damaged the concrete pavement on inserting the electrode into the pavement surface. This study examined the feasibility of the flat electrode method to observe the concrete pavement instead of the pole electrode method and analyzed the resistivity characteristics of the concrete by performing laboratory tests. METHODS : The resistivity of the concrete specimens manufactured with three different mixing ratios (38.50%, 39.50%, and 40.50%) were measured using the pole and flat electrode methods according to the concrete age (7 and 28 days) and electrode spacing (20 mm, 30 mm, and 40 mm). RESULTS :In both pole and flat electrode methods, the resistivity increased with increasing fine aggregate proportion regardless of the concrete age. The resistivity measured at a concrete age of 28 days was slightly larger than that measured at 7 days. In the case of a concrete age of 7 days, the resistivity measured by the flat electrode method was larger than that measured by the pole electrode method. The difference disappeared at 28 days. CONCLUSIONS :The results suggest that the flat electrode method can replace the pole electrode method because the resistivity measured by both methods was similar. Hence, the development of a technology to apply the flat electrode method to actual concrete pavement is necessary.

• 한국구조물진단유지관리공학회 논문집
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• 제17권6호
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• pp.122-129
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• 2013

콘크리트의 전기저항은 염소이온 확산계수와 비교하여 빠르고 간단히 측정할 수 있기 때문에, 염소이온 확산계수를 제어하기 위한 간접적인 지표로서 활용될 수 있다. 전기저항은 해양구조물의 유지관리 전략을 수립하는데 매우 중요하다. 본 연구의 목적은 전기저항측정의 프로토콜을 설계하는 것이다. 본 연구는 염소이온과의 관계성을 토대로 콘크리트의 성능을 파악하는 중요한 비파괴 접근방법을 제시하였다. 수분, 공극량, 공극간 굴곡특성 등과 같은 미세구조 특성이 전기저항에 미치는 영향을 배합조건별 수화단계별로 고찰하였다. 전기저항과 염소이온 확산계수의 관계로부터 정규적인 전기저항의 측정을 토대로 염소이온 확산계수를 간접적으로 통제하는데 본 성과가 이용될 수 있다.

• Computers and Concrete
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• 제21권1호
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• pp.1-9
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• 2018

Electrical resistivity is a property associated with both the physical and chemical characteristics of concrete. It allows the evaluation of the greater or lesser difficulty with which aggressive substances penetrate the concrete's core before the dissolution of the passive film process and the consequent reinforcement's corrosion begin. This work addresses the steel fiber addition to concrete with two types and various contents from 0% to 1.3%, correlating it with its electrical resistivity. To that effect, 9 different mixes of steel fiber reinforced concrete (SFRC) were produced. The electrical resistivity was evaluated on the on six years aged SFRC by direct measurement at different frequency from 0.1 kHz to 100 kHz. The results indicate that steel fiber content is strongly conditioned by the type and quantity of the additions used. It was also found that long type of fibers has more effect on decreasing the electrical resistivity of concrete than short fibers. Therefore, they increase the corrosion risk of concrete depending on fiber volume fraction and moisture percentage.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.457-459
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• 2006

In this paper was analyzed and compared the resistivity characteristic of concrete between moisture condition and dry condition to measure the variation of resistivity by water after making concrete scale block. The resistivity was decreased when the moisture of concrete block was gradually increased.