• Title/Summary/Keyword: 균열 자기치유

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Influence of Exposure Environmental Conditions on the Crack Healing Performance of Self-healing Repair Mortar Specimens (노출환경 조건이 자기치유형 보수 모르타르 시험체의 균열 치유성능에 미치는 영향)

  • Lee, Woong-Jong;Lee, Hyun-Ho;Ahn, Sang-Wook;Lee, Kwang-Myong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.4
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    • pp.283-288
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    • 2018
  • Since the crack self-healing materials are activated according to the exposure environmental conditions from the time of crack occurrence, it is very important to clarify the relationship between the healing performance and the exposure environmental conditions of the crack surface. In this paper, the influence of the exposure environmental conditions on the crack healing performance of self-healing repair mortar was investigated through the water permeability test. The influence of temperature and humidity on the crack width of cracked specimens was evaluated. As a result of measuring the change of the crack width, the effect of curing temperature was negligible but it was confirmed that crack-closing occurred due to the change of dry-wet condition. The healing materials produced on the crack surface of the specimens was identified as calcite minerals. Since the minerals with high density are precipitated under the influence of gravity, the healing performance is somewhat different according to the direction of the crack surface, and the healing performance was significantly improved in the wet exposure condition than the air exposure condition.

A Study on Crack Healing Properties of Cement Composites Mixed with Self-healing Microcapsules (자기치유 마이크로 캡슐을 혼합한 시멘트 복합재료의 품질 및 균열 치유 특성에 관한 실험적 연구)

  • Choi, Yun-Wang;Oh, Sung-Rok;Kim, Cheol-Gyu;Nam, Eun-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.113-121
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    • 2019
  • In this study, self - healing microcapsules which can be mixed directly with cement composites were prepared, and the quality and crack healing performance of cement composites with self - healing microcapsules were evaluated. In the past, it has been focused on evaluating self-healing capsules and crack healing properties. Therefore, self - healing microcapsules have been studied for their effect on the quality of cement composites when mixed with cement composites. The table flow and the air flow rate of the cement composite material mixed with self-healing microcapsules were found to have no significant influence on table flow and air volume regardless of mixing ratio. Compressive strength and splitting tensile strength tended to decrease with increasing capsule mixing ratio. As a result of evaluation of crack healing properties according to water flow, initial water permeability decreased, and reaction products were generated over time and cracks were healed.

The Effect of Crack Self-Healing Hybrid Capsules Composition Ratio on the Healing Properties of Cement Composites (균열 자기치유 하이브리드캡슐 조성비에 따른 시멘트 복합재료의 치유특성에 미치는 영향)

  • Choi, Yun-Wang;Nam, Eun-Joon;Park, Jun-Ho;Oh, Sung-Rok
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.3
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    • pp.335-342
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    • 2022
  • In this study, self-healing hybrid capsules were prepared by mixing self-healing solid capsules and self-healing microcapsules using inorganic materials as core materials. Self-healing hybrid capsules were mixed with 3 % according to the composition ratio of 3:7, 5:5, and 7:3 based on the mass of the cement to prepare a self-healing cement composite material. The healing properties of crack self-healing hybrid capsules were evaluated through hydrostatic water permeability test and surface crack monitoring. It was found that the self-healing hybrid capsules prepared by mixing the composition ratio of the self-healing solid capsules and the self-healing microcapsules at 7:3 has a great effect on improving the crack self-healing performance.

Development of Crack Monitoring System for Self-healing Repair Mortar Surface Using Image Processing Technique (이미지 처리 기법을 이용한 자기치유 보수 모르타르 시공표면의 균열 모니터링 시스템 개발)

  • Oh, Sang-Hyuk;Moon, Dae-Jung;Lee, Kwang-Myong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.3
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    • pp.359-366
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    • 2021
  • In this study, It was developed an monitoring cracks system based on image processing techniques in order to measure cracks, which are major damages in concrete, and to convert them into a database. The crack monitoring system consists of crack image captured equipment and a crack detection and analysis software. This system provides objective and quantitative data by replacing the conventional visual inspection. The crack detection algorithm w as verified through an indoor test using virtual cracks, and the amount of crack detection and crack width change was monitored by applying it to the self-healing repair mortar construction site. In the case of the crack width detected through image analysis, the maximum difference from the actual crack width was 0.0334mm. It was possible to detect microcracks of 0.1mm or less, and the effect of crack healing over time of the self-healing repair mortar was confirmed trough the field test.

Evaluation Method of Healing Performance of Self-Healing Materials Based on Equivalent Crack Width (등가균열폭에 기반한 자기치유 재료의 치유성능 평가 방법)

  • Lee, Woong-Jong;Kim, Hyung-Suk;Choi, Sung;Park, Byung-Sun;Lee, Kwang-Myong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.3
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    • pp.383-388
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    • 2021
  • In this study, constant head water permeability test was adopted to evaluate self-healing performance of mortars containing inorganic healing materials which consist of blast furnace slag, sodium sulfate and anhydrite. Clinker powder and sand replaced for a part of cement and fine aggregates. On constant head water permeability test for self-healing mortars, unit water flow rate of mortar specimens were measured according to crack width and healing period. As a result of evaluating the healing performance of self-healing mortar, it was confirmed that with the initial crack width of 0.3mm, the healing rate at healing period of 28 days increased by more than 30%p compared to plain mortar, greatly improving the healing performance. Furthermore, the coefficient(α) which was estimated from the relationship between crack width and unit water flow rate was used for calculating equivalent crack width. By analyzing the correlation of healing rate and equivalent crack width, the time and initial crack width attaining healing target crack width were predicted.

Evaluation of Self-Healing Performance for Mortar Beams Containing Self-Healing Materials (자기치유 재료 혼입 모르타르 보의 자기치유 성능 평가)

  • Shin, DongIk;Muhammad, Haroon;Min, Kyung Sung;Lee, Kwang-Myong;Lee, Jung-Yoon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.1
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    • pp.67-73
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    • 2020
  • In this study, the self-healing performance of mortar beams containing self-healing materials was evaluated through experiments. Normal mortar beams and self-healing mortar beams were used In the experiments. The self-healing performance was evaluated by comparing the mortar compressive strength, member strength, and self-healing effects of cracks. The experimental results showed that the compressive strength of mortar containing self-healing material was smaller than that of normal mortar, but the ratio of 118 days compressive strength to 28 days compressive strength was the same. The member strength tended to increase with increasing curing period. In normal mortar specimens, the member strength did not recover even if the curing period increased, but the strength of the self-healing mortar specimens tended to recover as reaction products were produced. The crack width tended to decrease after the healing periods in both specimens, but the reaction product was observed only in the self-healing mortar specimens.

Healing Performance of Concrete Containing Hybrid Self-healing Materials (하이브리드 자기치유 소재를 혼입한 콘크리트의 치유성능)

  • Mih-ho, Hwang;Hyuk, Kwon;Hyung-Suk, Kim;Sung, Choi;Kwang-Myong, Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.569-576
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    • 2022
  • In this study, the healing performance of hybrid self-healing concrete was investigated by mixing bacterial pellets(BP) and solid phase capsules(SC), respectively, based on organic-inorganic self-healing material(MC). Constant water head permeability test was applied as a method of evaluating the healing performance, and the healing rate and the healed crack width calculated by the equivalent crack width were used as evaluation indicies. As a result of the water permeability test, when the initial crack width was 0.3 mm, the healing rates of MC-BP and MC-SC were 2.1~3.0 %pt higher than that of MC, and the healed crack width of hybrid concrete increased by 0.017~0.018 mm. In conclusion, it was found that the self-healing performance was not significantly improved even if the two types of healing materials are used together.

Self Healing System for Concrete Surface Crack using Polymer based Coating Agent Incorporating Microencapsulated Healing Agent (마이크로캡슐을 함유한 폴리머 코팅제의 콘크리트 표면균열 자기치유시스템)

  • Shin, Ki-Su;Ryu, Byung-Chul;Wang, Xiao-Yong;Park, Ki-Bong
    • Journal of the Korea Institute of Building Construction
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    • v.15 no.6
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    • pp.579-587
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    • 2015
  • In this paper, microencapsulated healing agent was embedded in the polymer matrix to obtain self healing properties. Microencapsulation of methacrylate using polyurea-formaldehyde as a shell material and studied the effect of agitation rate on capsule characteristics such as size, shell thickness, and surface morphology. The formation of microcapsules was confirmed by FTIR and TGA, and capsule characteristics were studied by optical microscopy and SEM. The self-healing effect was evaluated using permeability measurements and further confirmed by surface analytical tools including optical microscope. According to the experimental results, the microencapsulated healing system has the self-heaing ability for artificial cracks.

Assessment of Recovery of Chloride Penetration Resistance of Self-healing Cement Mortars Containing Layered Double Hydroxide (이중층수산화물을 혼입한 자기치유 시멘트 모르타르의 염화물 침투 저항성 회복 평가)

  • Kyung Suk, Yoo;Seung Yup, Jang
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.600-608
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    • 2022
  • This study investigates the effect of layered double hydroxide (LDH) on the healing performance of self-healing concrete by assessing the chloride penetration resistance of self-healing cement mortars using electrical chloride ion migration-diffusion test. Test results show that both mortars containing healing materials only and mortars containing healing materials and Ca-Al LDH together mostly had higher migration-diffusion coefficients right after cracking, but the migration-diffusion coefficients decreased more than that of OPC with increasing healing ages, and thus, they yielded higher healing capacities than OPC. Also, mortars containing Ca-Al LDH together with healing materials showed higher reduction of their migration-diffusion coefficients, and thus, higher healing capacities than mortars containing healing materials only. This suggests that as the self-healing product increases on the crack surface, the binding of chloride ions by LDH inside the crack increases.

The Self-healing and Ageing Effect of OPC-GGBFS Cement in Sea-water and Tap-water (해수와 담수에서 OPC-GGBFS 시멘트의 자기치유와 재령효과)

  • Kim, Tae-Wan;Kang, Choonghyun
    • Journal of the Korea Concrete Institute
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    • v.29 no.1
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    • pp.11-21
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    • 2017
  • The paper presents experimental results of self-healing effects of OPC-GGBFS paste with cracked and uncracked specimens. The self-healing of cracked specimens is processes of crack closing with re-hydration of unhydrated in crack surface. The OPC paste with GGBFS replacement ratios of 0%, 10%, 20% and 30% were prepared having a constant water-binder ratios of 0.5. The OPC-GGBFS paste specimens immersed in tap-water and sea-water. The temperature of tap and sea-water was $5^{\circ}C$, $15^{\circ}C$ and $25^{\circ}C$. The cracked specimens after deterioration were immersed for 60 days. The relationship between self-healing effect and age-effect was calculate based upon the experimental results. The self-healing effect was measured in ultrasonic pulse velocity (UPV) before and after loading. When the relative change rate of UPV is increases with the increase in GGBFS replacement ratios. Moreover, the self-healing effect is increased with the temperature of tap-water is increase. But the cracked specimens immersed in sea-water was unclear effects of different temperature. Furemore, most of the healing for OPC-GGBFS specimens immersed in tap-water and sea-water occurred during the first 30 days. The self-healing effect until 30 days is higher than that the age-effect. After 30 days, self-effect and age-effect was largely decreases. SEM/EDS analysis of crack on the surface of the specimens in tap-water were covered with aragonite, and sea-water were covered with brucite.