• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.3
• /
• pp.335-342
• /
• 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.

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

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.1
• /
• pp.67-73
• /
• 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 Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.569-576
• /
• 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
• /
• v.10 no.4
• /
• pp.577-583
• /
• 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 Korea institute for structural maintenance and inspection
• /
• v.23 no.1
• /
• pp.113-121
• /
• 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.

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

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.600-608
• /
• 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.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.4
• /
• pp.289-296
• /
• 2016

In this study, the self-healing effect of a fiber-reinforced cement composite (FRCC) was examined using a drying-wetting test and an outdoor exposure test. The influence of various curing conditions on the self-healing effect of the FRCC was also investigated. The effect of self-healing was evaluated using a permeability coefficient and by investigating the cracks using a optical microscope. The results confirmed that the FRCC was capable of self-healing under a long wetting time and a low drying temperature. In addition, watertight performance by self-healing was shown to have a significant influence on wetting time. Meanwhile, this self-healing effect was enhanced by hydration as a result of rainfall when the FRCC was put under actual environmental conditions. Moreover, it was determined that cracking self-healing can be improved by using the appropriate admixture materials.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.3
• /
• pp.383-388
• /
• 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.