• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.295-299
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• 2021

Recently, interest in maintenance has been increasing due to the enlargement and aging of infra structures. Therefore, a new paradigm is required to secure and improve the durability of structures differentiated from the past. Accordingly, research on smart concrete incorporating the concept of self-healing into concrete is being actively conducted. In this study, the crack healing performance and durability performance of self-healing concrete applied with a hydrogel containing biomineral-forming microorganisms were evaluated. As a result of evaluating the dispersion of the hydrogel in concrete, it was confirmed that the hydrogel was well distributed in concrete matrix with a dispersion coefficient of 0.35 to 0.46. The crack healing performance evaluation was verified by a water permeability test, and showed a recovery rate of 95% or more at the age of 28 days, confirming the applicability of self-healing concrete. The durability performance of self-healing concrete was evaluated in terms of resistance to penetration of chloride ion and freezing and thawing. Regardless of the mixing of the hydrogel, the same level of durability performance was shown for various compressive strength level. Therefore, it was confirmed that the microbial admixture did not affect concrete durability. In the future, long-term crack healing performance and durability verification studies should be supplemented.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.577-583
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• 2022

In this study, the characteristics of self-healing mortars produced using an inorganic self-healing material consisting of ground granulated blast furnace slag, expansion agent, and anhydrite, were investigated. For three types of self-healing mortars with different amounts of the inorganic healing material, compressive strength was measured and the self-healing performance was evaluated through the constant water head permeability test. The healing rate and equivalent crack width according to crack-induced aging were used as indicies of healing performance evaluation. Considering the development of compressive strength of the self-healing mortars, the change in the healing rate with healing periods, and the economic feasibility, the optimal amount of inorganic self-healing materials was suggested as 20 % of the mass of cement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.531-538
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• 2022

In this study, the self-healing hybrid capsules were prepared, were mixed with 3 %, 5 %, and 7 % based on cement mass. The healing performance were evaluated according to mixing ratio self-healing hybrid capsule. As a result of the experiment, it was found that the crack healing performance improved as the mixing rate of the self-healing hybrid capsule increased, but the quality performance tended to decrease. Therefore, it is judged that using the mixing ratio of the hybrid capsule within 5 % reduces the quality performance to within about 10 % and secures about 90 % or more of the healing performance.

• Advances in concrete construction
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• v.15 no.1
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• pp.11-22
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• 2023

Autogenous healing of concrete can be helpful in structural maintenance by healing cracks using a healing material created by the precipitation of calcite and by the hydration of unhydrated binder around the cracks. Against this backdrop, this study investigated the physicochemical properties and autogenous healing performance of ternary blended binder composed of ordinary Portland cement (OPC), blast furnace slag (BFS), and calcium sulfoaluminate (CSA) clinker. Ternary blended binders with various contents of OPC-BFS-CSA clinker were prepared, and their physicochemical properties and autogenous healing performances were examined using various analytical techniques and visually observed using a microscope. The obtained results indicated that increase in the BFS content accompanied the increased the amount of unreacted BFS even after 28 days of curing and had a positive effect on the autogenous healing performance due to its latent hydration. However, replacing the CSA clinker did not increase the autogenous healing performance owing to an insufficient sulfate source for the formation of ettringite. The main precipitates around the cracks were calcite, C-S-H. Other hydration products such as portlandite, monosulfate, and ettringite, which were not found in the Raman and scanning electron microscope analyses.

• 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.

• 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.

• 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.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.109-114
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• 2012

This study is the things to experiment and evaluate the performance of self-healing water-proofing on the concrete to be using the crystal growth composite waterproofing admixture. The cylinder to be making on the concrete by ${\varnothing}150{\times}300$ mm for evaluating the performance of self-healing water-proofing was aging 90 days and cut on a 50 mm. So, it prompted the crack and applied. After it measured the quantity of water to be flow the water throughout the crack part of the cylinder, it applied the basic formular of Darcy's law and calculated the coefficient of water permeability. So, it verified the performance of self-healing water-proofing on the basis of the changing shape of the water permeability. This experiment is the thing to be applied the general evaluation of the structure to demand the real watertightness on doing for the evaluating of performance of the quantity of water leak and self-healing water-proofing about the various penetration crack.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.673-684
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• 2021

Background and objective: This study seeks to investigate domestic agro-healing farm resources so that preliminary data can be obtained on the systematic provisions for agro-healing programs in order to improve service quality and to identify the quality of agro-healing policy services. Methods: For this study, owners of agro-healing facilities were asked 24 questions via an online survey. An importance-performance analysis (IPA) was conducted to identify service quality for each policy sector. Results: Respondents' satisfaction levels were low when compared to agro-healing farm owners' perceptions of the above-average importance of each sector. The results from the resource analysis of domestic agro-healing farms indicated that the main operational purposes of farms were, in descending order, experience (90.0%), healing (86.7%), and education (84.0%). With respect to the type of program that was operated, cultivating crops (horticultural therapy) was identified most frequently at 83.3%. Conclusion: As a result of this study, the resources possessed by agro-healing farms were identified. In addition, the results of the IPA analysis in terms of service quality are not as good as expected, and performance levels should be increased to improve this. The results of this study are expected to provide useful information not only to improve the quality of agro-healing services, but also to revitalize the agro-healing industry while developing a systematic agro-healing program.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.367-374
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• 2021

In this study, the applicability of mechanochemical process for the manufacture of self-healing admixtures and the effect of mechanochemical process on the self-healing performance were evaluated. The self-healing admixtures were adopted as a highly reactive materials(expansive agent, swelling material and crystal growth agent) for mechanochemical processes. The self-healing admixtures for the mechanochemical process application were evaluated by X-Ray Diffraction and Fourier Transform Infrared Spectroscopy analysis, water permeability performance was used to evaluate self-healing performance of mortar. As a result of the evaluation, the self-healing performance of the WM(With-Mortar)3 sample to which mechanochemical process increased by 4.1% compared to the WM1 sample that was not treated, and the average healing index was 94.3%.