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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 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.