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The management of plastic waste is a massive challenge and the recycling of plastics for newer applications is a potential solution. This study investigates the feasibility of using polyethylene terephthalate (PET) powder in cementitious composites. The changes in the strength and microstructure of Portland cement incorporating PET powder with different replacement ratios were systematically analyzed through the measurements of compressive strength, isothermal calorimetry, X-ray diffraction, thermogravimetric analysis, and Raman spectroscopy. In addition, the possible chemical changes of cement paste samples were studied upon exposure to different conditions, including deionized water, seawater, and simulated pore solution. Based on the test results and analysis, no apparent chemical changes were observed in the cement paste samples, regardless of the exposure conditions. In contrast, the PET powder incorporated into concrete exhibited remarkable changes, which may have occurred during the mixing process. The results also suggested that the maximum replacement ratio of PET powder should be less than 10% of the binder (by mass) to minimize its influence on cement hydration, due to the interaction between water and PET. The PET-containing samples showed the presence of calcium aluminate hydrates which were absent in the neat paste sample.
Min Kim; Jun Park; Taek Han; JoonHo Seo; Solmoi Park. Influence of Polyethylene Terephthalate Powder on Hydration of Portland Cement. Polymers 2021, 13, 2551 .
AMA StyleMin Kim, Jun Park, Taek Han, JoonHo Seo, Solmoi Park. Influence of Polyethylene Terephthalate Powder on Hydration of Portland Cement. Polymers. 2021; 13 (15):2551.
Chicago/Turabian StyleMin Kim; Jun Park; Taek Han; JoonHo Seo; Solmoi Park. 2021. "Influence of Polyethylene Terephthalate Powder on Hydration of Portland Cement." Polymers 13, no. 15: 2551.
The present study investigated the structural evolution of Portland cement (PC) incorporating supplementary cementitious materials (SCMs) exposed to seawater. The samples were made with replacing Portland cement with 10 mass-% silica fume, metakaolin or glass powder. The reaction degree of SCMs estimated by the portlandite consumption shows that metakaolin has the highest reaction degree, thus metakaolin-blended PC exhibits the highest strength. The control exposed to seawater exhibited 14.82% and 12.14% higher compressive strengths compared to those cured in tap water at 7 and 28 days. The samples incorporating metakaolin showed the highest compressive strength of 76.60 MPa at 90 days tap water curing and this was 17% higher than that of the control. Exposure to seawater is found to retard the rate of hydration in all SCM-incorporating systems, while the strength development of the neat PC system is enhanced. The main reaction product that forms during exposure to seawater is Cl-AFm and brucite, while it is predicted by the thermodynamic modelling that a significant amount of M-S-H, calcite and hydrotalcite is to form at an extended period of exposure time.
Solmoi Park; Jun Park; Namkon Lee; Min Kim. Exploring Structural Evolution of Portland Cement Blended with Supplementary Cementitious Materials in Seawater. Materials 2021, 14, 1210 .
AMA StyleSolmoi Park, Jun Park, Namkon Lee, Min Kim. Exploring Structural Evolution of Portland Cement Blended with Supplementary Cementitious Materials in Seawater. Materials. 2021; 14 (5):1210.
Chicago/Turabian StyleSolmoi Park; Jun Park; Namkon Lee; Min Kim. 2021. "Exploring Structural Evolution of Portland Cement Blended with Supplementary Cementitious Materials in Seawater." Materials 14, no. 5: 1210.
This study aims to investigate the interfacial bond between epoxy resin coatings and concrete substrates exposed to different exposure conditions. As test variables, five different epoxy resins, three exposure conditions, and four exposure times were selected and investigated. The exposure conditions significantly affected the pull-off strength. As the exposure times increased, the pull-off strength decreased, except for bisphenol A with cresyl glycidyl ether (BGEI). BGEI showed the highest pull-off strength during exposure to tap water (3.78 MPa) and seawater (3.66 MPa). However, adding phenolic novolac resin and hexanediol diglycidyl ether, which were reactive diluents, reduced the pull-off strength during tap water exposure compared to that observed during seawater exposure, owing to the penetration of tap water. Therefore, the pull-off strength in the exposure environment must be considered before using reactive diluents and fillers in epoxy coatings.
Jun Kil Park; Min Ook Kim. The effect of different exposure conditions on the pull-off strength of various epoxy resins. Journal of Building Engineering 2021, 38, 102223 .
AMA StyleJun Kil Park, Min Ook Kim. The effect of different exposure conditions on the pull-off strength of various epoxy resins. Journal of Building Engineering. 2021; 38 ():102223.
Chicago/Turabian StyleJun Kil Park; Min Ook Kim. 2021. "The effect of different exposure conditions on the pull-off strength of various epoxy resins." Journal of Building Engineering 38, no. : 102223.
This study aims to investigate the effects of different exposure conditions on the interfacial bond between steel plates and epoxy resin coatings at early ages. Test variables include the epoxy resin types, exposure conditions, exposure periods, and coating equipment. The selected epoxy resins were applied to prepared steel plates and cured at each exposure condition for 7, 28, 56, or 91 days, and the pull-off bond strength and coating thickness were measured. Scanning electron microscopy (SEM) images were obtained to study the interfacial bond for some representative coatings. Three different exposure conditions (indoors and actual marine environment) were considered in this study. This study is also focusing on the improvement of previously developed underwater coating equipment and evaluating the performance. Experiments were conducted to evaluate the performance of the improved equipment types under different environmental conditions: indoors (tap water and seawater) and outdoor conditions. The improved equipment types were confirmed to be effective for underwater coating and easier to use than the previous equipment under real sea conditions. The experimental results also confirmed that the bond strength of the coating decreased as the curing time increased.
Sungwon Kim; Hyemin Hong; Jun Kil Park; Sangmin Park; Seoung Ik Choi; Min Ook Kim. Effect of Exposure Conditions on the Interfacial Bond Properties of SS400 Plate Coated with Various Epoxy Resins. Coatings 2020, 10, 1159 .
AMA StyleSungwon Kim, Hyemin Hong, Jun Kil Park, Sangmin Park, Seoung Ik Choi, Min Ook Kim. Effect of Exposure Conditions on the Interfacial Bond Properties of SS400 Plate Coated with Various Epoxy Resins. Coatings. 2020; 10 (12):1159.
Chicago/Turabian StyleSungwon Kim; Hyemin Hong; Jun Kil Park; Sangmin Park; Seoung Ik Choi; Min Ook Kim. 2020. "Effect of Exposure Conditions on the Interfacial Bond Properties of SS400 Plate Coated with Various Epoxy Resins." Coatings 10, no. 12: 1159.
This study summarizes existing studies on plastic recycling to determine whether ocean plastics with high pollution degrees could be used for cement-based materials. In particular, the methods to recycle plastic waste, the effects of recycled plastic on the physical and mechanical properties of cement-based materials, and their effective usage were investigated. Workability, density, compressive strength, split tensile strength, and flexural strength of cement-based materials with recycled plastics were reviewed and divided into recycled aggregates and fibers. Based on the previous investigation, the direction of research necessary to recycle marine plastics is suggested. As the amount of recycled plastic aggregate increased, the mechanical strength of cement-based materials decreased. The recycled plastic aggregate lowered the density and increased porosity of the cement-based material. Meanwhile, recycled plastic fibers reduced the compressive strength but improved the tensile strength; to effectively improve tensile strength, a volume content of less than 1.5% should be added to prevent balling fibers. Furthermore, an appropriate aspect ratio should be determined based on the type of plastic to be used.
Jun Park; Min Kim. Mechanical Properties of Cement-Based Materials with Recycled Plastic: A Review. Sustainability 2020, 12, 9060 .
AMA StyleJun Park, Min Kim. Mechanical Properties of Cement-Based Materials with Recycled Plastic: A Review. Sustainability. 2020; 12 (21):9060.
Chicago/Turabian StyleJun Park; Min Kim. 2020. "Mechanical Properties of Cement-Based Materials with Recycled Plastic: A Review." Sustainability 12, no. 21: 9060.
In this study, recycled waste fishing net (WFN) short fibers were proposed to be used as short fiber reinforcements. The pullout resistance of WFN short fibers embedded in cement mortar was investigated by conducting fiber pullout tests. Three types of WFN short fibers and two types of commercial polypropylene (CP) fibers were investigated. To quantitatively compare the pullout resistance of WFN short fibers and CP fibers, pullout parameters, including peak pullout load (peak bond strength), peak fiber stress, slip at peak load, and pullout energy (equivalent bond strength) of the pullout specimens, were analyzed. In addition, the analysis of fiber images, captured by using a stereoscopic digital microscope, before and after pullout tests, elucidated the different mechanisms of fiber pullout corresponding to the type of fibers. The bundled structures of the WFN fibers generated mechanical interaction between fiber and matrix during fiber pullout; consequently, they produced higher bond resistance and more damage on the surface of fibers after the pullout. Therefore, the bundled WFN fibers showed comparable pullout resistance with CP fibers.
Jun Kil Park; Min Ook Kim; Dong Joo Kim. Pullout Behavior of Recycled Waste Fishing Net Fibers Embedded in Cement Mortar. Materials 2020, 13, 4195 .
AMA StyleJun Kil Park, Min Ook Kim, Dong Joo Kim. Pullout Behavior of Recycled Waste Fishing Net Fibers Embedded in Cement Mortar. Materials. 2020; 13 (18):4195.
Chicago/Turabian StyleJun Kil Park; Min Ook Kim; Dong Joo Kim. 2020. "Pullout Behavior of Recycled Waste Fishing Net Fibers Embedded in Cement Mortar." Materials 13, no. 18: 4195.
In this study, we investigated the mechanical behavior of waste fishing net (WFN) fiber-reinforced cementitious composites (FRCCs) subjected to direct tension to evaluate the possibility of using WFN fibers as reinforcement in cementitious composites. Three different WFN fibers, two commercial (C) polypropylene (PP) fibers, and two fiber volumes (0.5 and 1.0%) were considered as test variables to explore the effect of adding WFN fiber to a cement mortar. As the fiber volume was increased, both the compressive and first cracking strengths decreased, while the post-cracking strength increased. Reinforced samples (WFN3-FRCCs) with a 0.5% fiber volume exhibited the highest compressive strength, while those with a fiber volume of 1.0% had the highest post-cracking strength. The compressive and post-cracking strengths of WFN3-FRCCs were 6–10% and 2–13% higher than those of C-FRCCs, respectively. Therefore, WFN-fibers consisting of twisted yarns, which generate mechanical bonds during fiber pull-out, are appropriate for reinforcing cement mortar, thereby improving their strength and ductility under tensile loads.
Jun Kil Park; Dong Joo Kim; Min Ook Kim. Mechanical behavior of waste fishing net fiber-reinforced cementitious composites subjected to direct tension. Journal of Building Engineering 2020, 33, 101622 .
AMA StyleJun Kil Park, Dong Joo Kim, Min Ook Kim. Mechanical behavior of waste fishing net fiber-reinforced cementitious composites subjected to direct tension. Journal of Building Engineering. 2020; 33 ():101622.
Chicago/Turabian StyleJun Kil Park; Dong Joo Kim; Min Ook Kim. 2020. "Mechanical behavior of waste fishing net fiber-reinforced cementitious composites subjected to direct tension." Journal of Building Engineering 33, no. : 101622.
This is an experimental study showing the effect of four types of polymers (acrylate polymer (AC), polyvinyl alcohol (PVA), styrene–butadiene rubber (SBR), and ethylene-vinyl acetate (EVA)) on the mechanical properties of polymer-modified cement mortars (PCMs). One polymer dosage was used in this study (3%), and the effect of this dosage on PCMs was compared with a control mortar mix with 0% polymer. The compressive, flexural, and pull-off bond strengths were measured and compared with previous results in works of literature. The effect of polymer addition on improving the mechanical properties of PCMs was clarified, and this effect was more obvious on the flexural strength than that on the compressive strength. The PCMs containing EVA showed the best performance, with up to 33% and 63% increases in compressive and flexural strengths after 28 days, respectively. In comparison, AC, PVA, and SBR produced smaller (16%–46% compared to control) improvements in the flexural strength after 28 days. In general, PCMs containing EVA showed the best mechanical properties.
Min Ook Kim. Influence of Polymer Types on the Mechanical Properties of Polymer-Modified Cement Mortars. Applied Sciences 2020, 10, 1061 .
AMA StyleMin Ook Kim. Influence of Polymer Types on the Mechanical Properties of Polymer-Modified Cement Mortars. Applied Sciences. 2020; 10 (3):1061.
Chicago/Turabian StyleMin Ook Kim. 2020. "Influence of Polymer Types on the Mechanical Properties of Polymer-Modified Cement Mortars." Applied Sciences 10, no. 3: 1061.
In this study, coating equipment for the effective underwater repair of submerged structures was developed. The tensile bond characteristics of selected epoxy resin coatings were investigated by coating the surface of a specimen using each of the four types of equipment. Using the experimental results, the tensile bond strength and the coating thickness were analyzed according to the type of equipment, coating, and curing time. The results show that the type of coating equipment used had the greatest effect on the measured bond strength and coating thickness of the selected coatings. However, the effect of coating type and curing time on the bond strength and the thickness was observed to be insignificant. Compared with the developed equipment, the surface treatment of the coating was observed to be more effective when using the pre-existing equipment, and thus the bond performance of the coating was improved compared to using the pre-existing equipment. Based on the experimental results, improvements and needs involving the equipment for further research were discussed.
Sungwon Kim; Hyemin Hong; Taek Hee Han; Min Ook Kim; Kim; Hong; Han. Early-Age Tensile Bond Characteristics of Epoxy Coatings for Underwater Applications. Coatings 2019, 9, 757 .
AMA StyleSungwon Kim, Hyemin Hong, Taek Hee Han, Min Ook Kim, Kim, Hong, Han. Early-Age Tensile Bond Characteristics of Epoxy Coatings for Underwater Applications. Coatings. 2019; 9 (11):757.
Chicago/Turabian StyleSungwon Kim; Hyemin Hong; Taek Hee Han; Min Ook Kim; Kim; Hong; Han. 2019. "Early-Age Tensile Bond Characteristics of Epoxy Coatings for Underwater Applications." Coatings 9, no. 11: 757.
Interfacial bond properties of six different epoxy resins used to coat submerged concrete structures were investigated. Test variables included coating type, coating equipment, and underwater curing time. Coating thickness and pull-off bond strength were measured using commercially available test equipment. Coating thickness and bond strength varied greatly depending on the manufacturer. The standard (control) coating equipment positively influenced the bond strength compared to other equipment. The effect of curing time on the bond properties was not significant within the range of 24 to 72 h. Lastly, some important considerations for the underwater coating of actual marine and coastal concrete structures were discussed, and suggestions for future research are presented.
Boreum Won; Min Ook Kim; Sangmin Park; Jin-Hak Yi. Effects of Water Exposure on the Interfacial Bond between an Epoxy Resin Coating and a Concrete Substrate. Materials 2019, 12, 3715 .
AMA StyleBoreum Won, Min Ook Kim, Sangmin Park, Jin-Hak Yi. Effects of Water Exposure on the Interfacial Bond between an Epoxy Resin Coating and a Concrete Substrate. Materials. 2019; 12 (22):3715.
Chicago/Turabian StyleBoreum Won; Min Ook Kim; Sangmin Park; Jin-Hak Yi. 2019. "Effects of Water Exposure on the Interfacial Bond between an Epoxy Resin Coating and a Concrete Substrate." Materials 12, no. 22: 3715.
Despite considerable efforts focused on the utilization of industrial wastes, the application of low-calcium fly ash to the construction industry is limited to the partial substitution to ordinary Portland cement. High-temperature curing is a method via which fly ash can be completely utilized as an alkali-activated construction material; however, additional energy is required. In this study, the dual reaction of alkali activation and the pozzolanic reaction was proposed to manufacture ambient-condition-curable structural mortars. For this purpose, calcium hydroxide was used in fly ash activated by sodium hydroxide and sodium silicate solutions. A series of experiments, including compressive strength tests, X-ray diffraction, thermogravimetric analysis, heat of reaction, and mercury intrusion porosimetry, were conducted. The continuous pozzolanic reaction on the pre-formulated geopolymeric skeleton was found to significantly enhance the material properties. By the addition of silica fume and a 7:3 mixture of sodium hydroxide and sodium silicate solutions, the material strength increased to greater than 60 MPa at 56 days. The added silica fume as well as the reduced alkali content of the solution enhanced the reactions due to the active participation of the calcium ion supplied by the added hydrated lime in a high pH environment.
Sung-Hoon Kang; Yeonung Jeong; Min Ook Kim; Juhyuk Moon. Pozzolanic reaction on alkali-activated Class F fly ash for ambient condition curable structural materials. Construction and Building Materials 2019, 218, 235 -244.
AMA StyleSung-Hoon Kang, Yeonung Jeong, Min Ook Kim, Juhyuk Moon. Pozzolanic reaction on alkali-activated Class F fly ash for ambient condition curable structural materials. Construction and Building Materials. 2019; 218 ():235-244.
Chicago/Turabian StyleSung-Hoon Kang; Yeonung Jeong; Min Ook Kim; Juhyuk Moon. 2019. "Pozzolanic reaction on alkali-activated Class F fly ash for ambient condition curable structural materials." Construction and Building Materials 218, no. : 235-244.