• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.409-417
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• 2009

In this study, autogenous crack healing and artificial crack healing using electrochemical electro deposition method were conducted to compare in the aspects of corrosion monitoring. Furthermore, the analysis of impressed voltage characteristics, galvanic current and linear polarization resistance comparison, and photo image processing technique were performed for quantitative comparisons of healing ratio. As a result, it was found that, in view of impressed voltage of artificial crack healing, the measured voltage was increased as time goes by. From the galvanic test results of artificial crack healing, the current vs. potential distribution value were formed widely in comparison with autogenous crack healing. In this point, it was shown that artificial crack healing has more eleatic resistance capacity than autogenous crack healing technique. Finally, it was found that artificial crack healing was 1.63 times higher than autogenous healing in view of crack healing ratio.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.689-696
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• 2009

In this study, electro-deposition method was applied to heal cracks in various blended concrete. The performance of the method was indirectly monitored by measuring impressed voltage, electrolyte, galvanic current monitoring, linear polarization resistance, and directly by image analysis of the cracks. The indirect and direct monitoring values are compared to develop guidelines for relating the indirect measures to actual crack healing. As a result, It was found that impressed voltage was convergence to 2.9V after 20000 minutes. From the galvanic current test results of artificial crack healing, the corrosion resistance showed that the order of 0.4 $>$ 0.6 $>$ 0.5 water to cement ratio. Furthermore, in view of binder, the corrosion resistance order was calculated OPC $>$ 60%GGBS $>$ 10%SF $>$ 30%PFA. Finally, It was found that 76.47% of healed crack surface calculated from the artificial crack healing technique using electrochemical deposition method.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.492-498
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• 2017

A thermal barrier coating (TBC) with self-healing property for cracks was proposed to improve reliability during gas turbine operation, including structural design. Effect of healing agent on crack propagation behavior in TBCs with and without buffer layer was investigated through furnace cyclic test (FCT). Molybdenum disilicide ($MoSi_2$) was used as the healing agent; it was encapsulated using a mixture of tetraethyl orthosilicate and sodium methoxide. Buffer layers with composition ratios of 90 : 10 and 80 : 20 wt%, using yttria stabilized zirconia and $MoSi_2$, respectively, were prepared by air plasma spray process. After generating artificial cracks in TBC samples by using Vickers indentation, FCTs were conducted at $1100^{\circ}C$ for a dwell time of 40 min., followed by natural air cooling for 20 min. at room temperature. The cracks were healed in the buffer layer with the healing agent of $MoSi_2$, and it was found that the thermal reliability of TBC can be enhanced by introducing the buffer layer with healing agent in the top coat.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.435-441
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• 2017

Studies on self-healing have currently been diversified and the methods to evaluate the studies have become more diversified as well. Among them, the back-scattered electron (BSE) image acquired through the scanning electron microscope (SEM) is attempted as the means to evaluate the self-healing effect on cracks. In order evaluate by the BSE image, sophisticated pre-processing of specimen is critical and this injected inside the particle, pore and artificial crack of the hardener to stabilize the structure of the newly generated self-healing product and it enables to endure the stress on polishing without deformation. The impregnated specimen smoothen the surface to obtain the BSE image of high resolution that polishing is made for diamond suspension for wet polishing after dry polishing. As a result of evaluating the self-healing product on the impregnated and polished self-healing specimen, the generated product is formed from the surface of the artificial crack and the self-healing substances are confirmed as $Ca(OH)_2$ and C-S-H.

• Journal of the Korean Ceramic Society
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• v.56 no.5
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• pp.483-488
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• 2019

We studied whether chemical strengthening can heal the flaws on soda-lime silicate glass. Artificial surface cracks were introduced on the glass by sharp indentation with various loads of 0.1 to 10 N. Then, the glasses with flaws were treated by ion-exchanging in KNO₃ melt. The change in the dimension of the crack on glass was measured by a digital microscope and a scanning electron microscope. The chemical strengthening treatment enhances the strength of the glass with flaws. It is thought that the melted KNO₃ not only forms the depth of the compressed layer of 7.5 ㎛, but also heals the cracks by infiltrating them and expanding the glass on both sides of the cracks. The critical length (2c) of the cracks on soda-lime glass that can be healed by chemical strengthening is 50 ㎛ or less.

• 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.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.565-572
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• 2009

In this study, corrosion resistance of palm oil fuel ash (POFA) concrete as a blended concrete is evaluated by using electrochemical technique. The POFA is an industrial byproduct obtained from fuel ash after extracting palm oil from palm-tree. In order to obtain basic material characteristics of the POFA concrete, tests on compressive strength, slump, weight loss, bleeding and expansion ratio were carried out the early-aged POFA concrete. On the other hand, durability characteristics, both chloride penetration and carbonation depth test, were also conducted. Finally, corrosion resistance were evaluated by applying electro-chemical artificial crack healing technique, and the tests on the impressed voltage characteristic, galvanic current and linear polarization resistance. From the experimental results, it was found that long-term strength, bleeding, lower slump ratio, expansion ratio, chloride penetration, carbonation and corrosion resistance were improved by using the POFA due to activated pozzolanic reaction. It can be also mentioned that POFA concrete has a potential to be used as a cementitious binder for green-recycling resources.