• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.311-317
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• 2018

The new asphalt surface reinforcement method (ASRM) is one of the preventive maintenance methods in asphalt concrete pavements. The adhesion performance of new ASRM satisfied the standard of non-slip pavement and bridge waterproofing materials. As a results of durability tests (as wheel load, rolling bottle and UV resistance test), the new ASRM showed sufficient resistance to traffic and environmental loads. The waterproof and chemical resistance tests of new ASRM were conducted to evaluate whether the pavement could be protected from water and chemicals and the performances of new ASRM were satisfactory. Furthermore, the new ASRM demonstrated some rejuvenation effects due to its toughness increases in recycled asphalt concrete mixture by 5% compared to the conventional hot mix asphalt mixture using reclaimed asphalt pavement. In conclusion, the new ASRM was evaluated to protect the asphalt concrete pavement and increase the lifetime.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.50-51
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• 2015

In marine and coastal environments, penetration of chloride ions is one of the main mechanisms causing concrete reinforcement corrosion. Currently, most of experimental investigations about submerged penetration of chloride ions are started after the four weeks standard curing of concrete. The further hydration of cement and reduction of chloride diffusivity during submerged penetration period are ignored. To overcome this weak point, this paper presents a numerical procedure to analyze simultaneously cement hydration reaction and chloride ion penetration process. First, using a cement hydration model, degree of hydration and phase volume fractions of hardening concrete are determined. Second, the dependences of chloride diffusivity and chloride binding capacity on age of concrete are clarified. Third, chloride profiles in hardening concrete are calculated. The proposed numerical procedure is verified by using chloride penetration test results of concrete with different mixing proportions.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.277-278
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• 2010

This study aims for development of an addition-typed releasing agent, which has improved basic properties leading to reducing defects that commonly occur in releasing agents, such as surface damage, and capable of shortening finish processing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.433-436
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• 2008

Deterioration in the concrete structure are due to carbonation, chloride ion attack and frost attack. Therefore, concrete structure is needed to surface protection for increase durability using silicate impregnants. Thus, this study is concerned with self-cleaning and durability of silicate hydrophilic impregnants of concrete structure using lithium and potassium silicates. From the experimental test results, lithium and potassium silicates have a good properties as a carbonation resistance. Lithium and potassium silicates make good use of hydrophilic impregnants of concrete structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.152-158
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• 2007

This is a fundamental research to utilize alkali activated cement(AAC) in concrete. The compressive strength of AAC concrete were measured for the various mixing ratios of activator/fly ash, and the mixing ratios of water glass, NaOH, and water among the activators. The mixing ratio of fine and coarse aggregates was maintained constantly. The relationships between the compressive strength and mixing ratios were analyzed to find the optimal mixing ratio of AAC concrete. As the results, the optimal mixing ratio of activator/fly ash in AAC concrete was 0.7, and that of water glass, NaOH, water among the activator was 4.0:1.0:2.5 for the maximum compressive strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.975-978
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• 2008

To strengthen the technological competitiveness of the construction market in Korea, researches have been performed to replace the prescriptive design codes (PD) to the performance-based ones (PBD). As one of the basic requirements for PBDs, development of the optimized concrete material models for domestic applications have been tried by comparing and verifying the pre-existing models with the observations and quality evaluations of ready mixed concretes that are used in the domestic market. This paper shows the summary of the present state of the research progress in the areas of compressive strength and elastic modulus.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.49-52
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• 2008

The tensile and bond performance of GFRP rebar are different from those of conventional steel reinforcement. It requires some studies on concrete members reinforced with GFRP reinforcing bars to apply it to concrete structures. GFRP has some advantages such as high specific strength, low weight, non-corrosive nature, and disadvantage of larger deflection due to the lower modulus of elasticity than that of steel. Bridge deck is a preferred structure to apply FRP rebars due to the increase of flexural capacity by arching action. This paper focuses on the behavior of concrete bridge deck reinforced with newly developed GFRP rebar. A total of three real size bridge deck specimens were made and tested. Main variable was reinforcement ratio of GFRP rebar. Static test was performed with the load of DB-24 level until failure. Test results were compared and analyzed with ultimate load, deflection behavior.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.346-351
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• 2006

본 논문은 콘크리트 표면 균열 영상에서 균열의 특징을 추출하기 위해, 영상 처리 기법을 적용하여 균열의 특징(길이, 폭, 방향)을 자동으로 추출 및 처리 할 수 있는 기법을 제안한다. 본 논문에서 적용된 영상 처리 기법으로는 균열 영상의 빛을 보정하기 위하여 모폴로지 기법인 채움(Closing)기법을 적용한다. 균열의 경계를 명확히 추출하기 위하여 고주파 강화 필터링을 적용한 후, 8가지 색상(검정, 빨강, 파랑, 초록, 노랑, 자주, 주황, 하늘)으로 명암 값을 분류하고 그 중 빈도수가 가장 높은 색상을 가진 명암 값을 제거한 후에 추출한 영상을 이진화한다. 이진화된 영상에서 콘크리트 표면 균열의 실거리 측정을 위한 임의의 선을 제거하기 위하여 위치 히스토그램을 적용하여 임의의 선을 제거한다. 임의의 선이 제거된 균열 영상에서 $5\times5$ 마스크를 적용하여 균열을 확대시키고, 3차례에 걸쳐 잡음 제거연산을 수행하여 균열의 후보 영역을 선택한 후, 후보 영역으로부터 특정 균열들을 추출한다. 추출된 특정 균열을 모폴로지 기법인 제거(Opening) 연산을 수행하여 균열의 특징이 일정하게 유지되게 하고 미세하게 끊어진 부분을 보정하여 균열의 특징(길이, 방향, 폭)을 측정한다. 실제 콘크리트 표면 균열영상을 대상으로 실험한 결과, 특정 균열이 효율적으로 추출되었고, 특정 균열의 길이, 방향, 폭의 등이 정확히 추출 및 계산되었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.273-276
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• 2008

The use of FRP(Fiber Reinforced Polymer) bars to replace conventional steel bars in reinforcing concrete structures is currently encouraged by many structural engineers, especially for their noncorrosive properties. The partial inferiority of the bond and mechanical properties for FRP bars, however, leads to wider and deeper cracks compared with those of steel reinforced concrete structures. This paper presents experimental results of concrete beams reinforced with FRP bars tested under static loading conditions up to failure. The study focuses on the effects of the reinforcement ratio on the behavior of concrete beams at various stages during loading. The study also attempts to establish a theoretical basis for the development of simple and rational design procedures for concrete beams reinforced with FRP bars.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.83-91
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• 2015

With varying conditions of concrete surface, induced chloride contents are changed and this is a key parameter for steel corrosion and service life in RC (Reinforced Concrete) structures. Many surface enhancement techniques using impregnation have been developed, however the evaluation techniques for chloride behavior through doubly layered media and time-dependent diffusion are rarely proposed. This paper presents an analysis technique considering double-layer concrete and time-dependent diffusion behavior, and the results are compared with those from the previous test results through reverse analysis. The chloride profiles from the surface-impregnated concrete exposed to atmospheric, tidal, submerged zone for 2 years are adopted. Furthermore surface chloride contents and diffusion coefficients are obtained, and are compared with those from Life365. Through consideration of time effect, the relative error decreases from 0.28 to 0.20 in atmospheric, 0.29 to 0.11 in tidal, and 0.54 to 0.40 in submerged zone, respectively, which shows more reasonable results. Utilizing the diffusion coefficients from Life365, relative errors increases and it needs deeper penetration depth (e) and lower diffusion coefficient ratio ($D_1/D_2$) due to higher diffusion coefficient.