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Interested in concrete, mortar, paste, aggregate, phase change materials and so on.
An enormous amount of energy is required to maintain a comfortable indoor temperature. This increases carbon dioxide emission, which is problematic. Phase-change materials have been widely used to resolve this problem and improve the energy efficiency of buildings. However, phase change materials have a fundamental drawback—leakage and low thermal conductivity. A novel thermal energy storage aggregate (TESA) was developed to solve the drawbacks of zeolites impregnated with paraffin wax and coated with epoxy resins, silicon carbide, and silica fume. A mortar which 100% replacement of TESA presented compressive strength that achieved the requirement for building material. To investigate the thermal properties, thermogravimetric analysis (thermally stable below 142 °C), differential scanning calorimetry (melting point: 36.46 °C, freezing point 46.39 °C, latent heat storage capacity: 19.76 J/g), thermal conductivity and thermal behavior of mortar measurements were conducted. Thermal shock cycling was tested to evaluate the reliability of the TESA. Finally, the thermal energy storage performance was evaluated by laboratory-sized cell tests. A laboratory-sized cell test was conducted using a self-designed room model that resemble the actual construction. The indoor temperature of the cell specimen via 100% integration of TESA, reduced the maximum temperature during the heating period by approximately 22% compared with the control cell specimen. The experimental results indicate that TESA can be applied to wall-plastering cement mortar, reducing energy consumption by decreasing the indoor temperature and reducing the temperature fluctuation.
Dong Ho Yoo; In Kyu Jeon; Byeong Hun Woo; Hong Gi Kim. Performance of energy storage system containing cement mortar and PCM/epoxy/SiC composite fine aggregate. Applied Thermal Engineering 2021, 198, 117445 .
AMA StyleDong Ho Yoo, In Kyu Jeon, Byeong Hun Woo, Hong Gi Kim. Performance of energy storage system containing cement mortar and PCM/epoxy/SiC composite fine aggregate. Applied Thermal Engineering. 2021; 198 ():117445.
Chicago/Turabian StyleDong Ho Yoo; In Kyu Jeon; Byeong Hun Woo; Hong Gi Kim. 2021. "Performance of energy storage system containing cement mortar and PCM/epoxy/SiC composite fine aggregate." Applied Thermal Engineering 198, no. : 117445.
Incineration bottom ash is generated by the incineration of solid waste. Household solid waste is increasing every year and so is incineration bottom ash. This is a problem to treat the incineration bottom ash because the ash has many toxic components. Cement composites can solve this problem and there are many studies for using the bottom ash as fine aggregate. To evaluate the usage of incineration bottom ash, compressive strength, mercury intrusion porosimetry, scanning electron microscopy-backscatter electron, X-ray diffraction, and toxicity characteristic leaching processes were performed. When using incineration bottom ash up to 20% of substitution, the compressive strength in all cases was increased. This study showed how the filler effect appeared well in the cement composites through the scanning electron microscopy-backscatter electron, and mercury intrusion porosimetry. X-ray diffraction indicated the possibility of an alkali-silica reaction of the aggregate with the components of incineration bottom ash. This problem is an obstacle to applying the incineration bottom ash as a fine aggregate. In addition, the toxicity characteristic leaching process was shown to be under the threshold of the Korean standard, however, this should nuanced by the consideration of amorphity. Comprehensively, incineration bottom ash could be used as a fine aggregate of up to 20% of substitution. However, the pre-treatment would need to eliminate or reduce alkali reactive components and heavy metals.
Byeong-Hun Woo; In-Kyu Jeon; Dong-Ho Yoo; Seong-Soo Kim; Jeong-Bae Lee; Hong-Gi Kim. Utilization of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortars. Sustainability 2021, 13, 8832 .
AMA StyleByeong-Hun Woo, In-Kyu Jeon, Dong-Ho Yoo, Seong-Soo Kim, Jeong-Bae Lee, Hong-Gi Kim. Utilization of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortars. Sustainability. 2021; 13 (16):8832.
Chicago/Turabian StyleByeong-Hun Woo; In-Kyu Jeon; Dong-Ho Yoo; Seong-Soo Kim; Jeong-Bae Lee; Hong-Gi Kim. 2021. "Utilization of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortars." Sustainability 13, no. 16: 8832.
To solve the problem of black ice, many studies are being carried out. The key in recent days is enhancing the thermal conductivity of concrete. In this study, to improve the thermal conductivity, silicon carbide was used to substitute 50% and 100% of the fine aggregate. In addition, steel fiber is not only for enhancing the mechanical properties but could enhance thermal conductive material. Hence, the arched-type steel fiber was used up to a 1% volume fraction in this study. Furthermore, graphite was used for 5% of the volume fraction for enhancing the thermal conductivity. However, thermal damage would occur due to the difference in thermal conductivity between materials. Therefore, the thermal durability must be verified first. The target application of the concrete in this study was its use as road paving material. To evaluate the thermal durability, freeze–thaw and rapid cyclic thermal attacks were performed. The thermal conductivity of the specimens was increased with the increase in thermal conductive materials. Graphite has already been reported to have a negative effect on mechanical properties, and the results showed that this was the case. However, the steel fiber compensated for the negative effect of graphite, and the silicon carbide provided a filler effect. Graphite also had a negative effect on the freeze–thaw and rapid cyclic thermal attack, but the steel fiber compensated for the reduction in thermal durability. The silicon carbide also helped to improve the thermal durability in the same way as steel fiber. Comprehensively, the steel fiber enhanced all of the properties of the tests. Using 100% silicon carbide was considered the acceptable range, but 50% of silicon carbide was the best. Graphite decreased all the properties except for the thermal conductivity. Therefore, the content of graphite or using other conductive materials used should be carefully considered in further studies.
Byeong-Hun Woo; Dong-Ho Yoo; Seong-Soo Kim; Jeong-Bae Lee; Jae-Suk Ryou; Hong-Gi Kim. Effects of Thermal Conductive Materials on the Freeze-Thaw Resistance of Concrete. Materials 2021, 14, 4063 .
AMA StyleByeong-Hun Woo, Dong-Ho Yoo, Seong-Soo Kim, Jeong-Bae Lee, Jae-Suk Ryou, Hong-Gi Kim. Effects of Thermal Conductive Materials on the Freeze-Thaw Resistance of Concrete. Materials. 2021; 14 (15):4063.
Chicago/Turabian StyleByeong-Hun Woo; Dong-Ho Yoo; Seong-Soo Kim; Jeong-Bae Lee; Jae-Suk Ryou; Hong-Gi Kim. 2021. "Effects of Thermal Conductive Materials on the Freeze-Thaw Resistance of Concrete." Materials 14, no. 15: 4063.
This study focused on the assessment of the ice-melting performance of cement composites using silicon carbide as fine aggregate. To assess the ice-melting performance, two mechanical and three thermal properties were measured and the results were discussed. After measuring the mechanical and thermal properties, the ice-melting test was conducted to confirm the ice-melting performance and the mechanical variation was confirmed through a splitting tensile test. The specimen that used 30% of silicon carbide as fine aggregate showed the highest compressive strength of 68.24 MPa at the 28 days of curing age and the specimens that used 100% of silicon carbide as fine aggregate were the lowest compressive strength of 38.93 MPa at the 28 days of curing age. However, the compressive strength that the case of used 100% of silicon carbide was in the acceptable range. The flexural strength increased with silicon carbide contents of up to 70%. The thermal properties including the thermal conductivity, diffusivity, and specific heat capacity showed nearly the same behaviors. These properties increased with the increase of silicon carbide content. The reason for this phenomenon was related to the volumetric occupancy of silicon carbide in the cement composite. The ice-melting test showed the decreasing of melting time with the increase of the silicon carbide content. Comprehensively, it was demonstrated that the ice-melting performance enhanced for the same reason as the thermal properties and, silicon carbide could be used as fine aggregate for improving the thermal properties.
Byeong Hun Woo; In Kyu Jeon; Dong Ho Yoo; Hong Gi Kim; Jae-Suk Ryou. Ice-melting performance assessment of cement composites using silicon carbide as fine aggregate. Applied Thermal Engineering 2021, 194, 117113 .
AMA StyleByeong Hun Woo, In Kyu Jeon, Dong Ho Yoo, Hong Gi Kim, Jae-Suk Ryou. Ice-melting performance assessment of cement composites using silicon carbide as fine aggregate. Applied Thermal Engineering. 2021; 194 ():117113.
Chicago/Turabian StyleByeong Hun Woo; In Kyu Jeon; Dong Ho Yoo; Hong Gi Kim; Jae-Suk Ryou. 2021. "Ice-melting performance assessment of cement composites using silicon carbide as fine aggregate." Applied Thermal Engineering 194, no. : 117113.
When concrete structures are exposed to fire and high temperatures for an extended period of time, they become significantly less durable due to the decomposition of major hydration products and the evaporation of capillary water. A change in internal properties does not guarantee the stability of concrete structures and may reduce their life cycle. To preserve the durability and stability of concrete structures upon exposure to fire and high temperatures, fire-resistant mortar for exterior walls was developed in this work using zeolite, a phase change material (PCM), and magnesium hydroxide (MH). Zeolite was first coated with paraffin wax. Primary coated aggregates were then coated with MH, which was mixed with dissolved polyvinyl acetate to enhance adhesion on the surface of pre-coated aggregates. The physical and chemical properties of mortar mixed with different percentages of coated aggregates as a replacement for normal aggregates were evaluated by compressive strength tests, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Fire-resistant properties were investigated by residual compressive strength measurement tests, mass loss calculations, and mock-up tests to compare the internal temperature of mortar covered with normal and coated aggregate when heated in an electric furnace at 1000 °C. The residual compressive strength results showed a decrease in strength with a larger percentage of coated aggregates in the mortar. However, according to the mock-up test, control mortar covered with plain mortar took 5430 s (90.5 min) to reach a maximum temperature of 842 °C, while the mortar covered with 100% coated aggregate took 7170 s (119.5 min) to reach a maximum temperature of 735 °C. The obtained results indicate that the coated aggregate is a proper replacement for conventional aggregate in the development of fire-resistant mortar.
Dong Ho Yoo; In Kyu Jeon; Hong Gi Kim; Jun Suk Lee; Jae-Suk Ryou. Experimental evaluation of fire resistance performance of cement mortar with PCM/Mg(OH)2-based composite fine aggregate. Construction and Building Materials 2021, 287, 123018 .
AMA StyleDong Ho Yoo, In Kyu Jeon, Hong Gi Kim, Jun Suk Lee, Jae-Suk Ryou. Experimental evaluation of fire resistance performance of cement mortar with PCM/Mg(OH)2-based composite fine aggregate. Construction and Building Materials. 2021; 287 ():123018.
Chicago/Turabian StyleDong Ho Yoo; In Kyu Jeon; Hong Gi Kim; Jun Suk Lee; Jae-Suk Ryou. 2021. "Experimental evaluation of fire resistance performance of cement mortar with PCM/Mg(OH)2-based composite fine aggregate." Construction and Building Materials 287, no. : 123018.
In this paper, the effect of nano-SiO2 (NS) and MgO on the hydration characteristics and anti-washout resistance of non-dispersible underwater concrete (UWC) was evaluated. A slump flow test, a viscosity test, and setting time measurement were conducted to identify the impacts of NS and MgO on the rheological properties of UWC. The pH and turbidity were measured to investigate the anti-washout performance of UWC mixes. To analyze the hydration characteristics and mechanical properties, hydration heat analysis, a compressive strength test, and thermogravimetric analyses were conducted. The experimental results showed that the fine particles of NS and MgO reduced slump flow, increased viscosity, and enhanced the anti-washout resistance of UWC. In addition, both NS and MgO shortened the initial and final setting times, and the replacement of MgO specimens slightly prolonged the setting time. NS accelerated the peak time and increased the peak temperature, and MgO delayed the hydration process and reduced the temperature due to the formation of brucite. The compressive results showed that NS improved the compressive strength of the UWC, and MgO slightly decreased the strength. The addition of NS also resulted in the formation of extra C–S–H, and the replacement of MgO caused the generation of a hydrotalcite phase.
In Jeon; Byeong Woo; Dong Yoo; Jae Ryou; Hong Kim. Evaluation of the Hydration Characteristics and Anti-Washout Resistance of Non-Dispersible Underwater Concrete with Nano-SiO2 and MgO. Materials 2021, 14, 1328 .
AMA StyleIn Jeon, Byeong Woo, Dong Yoo, Jae Ryou, Hong Kim. Evaluation of the Hydration Characteristics and Anti-Washout Resistance of Non-Dispersible Underwater Concrete with Nano-SiO2 and MgO. Materials. 2021; 14 (6):1328.
Chicago/Turabian StyleIn Jeon; Byeong Woo; Dong Yoo; Jae Ryou; Hong Kim. 2021. "Evaluation of the Hydration Characteristics and Anti-Washout Resistance of Non-Dispersible Underwater Concrete with Nano-SiO2 and MgO." Materials 14, no. 6: 1328.