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그래핀 나노플레이트 및 카본블랙을 첨가한 아스팔트 혼합물의 공용성 평가
고동영,가현길,이시원,문성호 한국도로학회 2021 한국도로학회논문집 Vol.23 No.5
PURPOSES : Graphene nanoplates, which have recently been in the spotlight in various fields, are a layer of graphite used in pencil leads, with carbon arranged in hexagonal honeycomb shapes. The graphene is 0.2 nanometers thick, and it possesses high physical and chemical stability, high strength, and conductivity. These graphene nanoplates have been studied for application in various devices such as semiconductors and batteries, and in the construction sector, where they are used as additives to improve the durability of cement concrete. The purpose of this study was to investigate the physical, and functional properties of graphene-modified asphalt mixtures. METHODS : In this study, the graphene input content of asphalt mixture samples was determined using an asphalt performance grade (PG) test. Based on the results of the test, their strength, stiffness, thermal properties, and electrical conductivity were evaluated. Indirect tensile strength test and dynamic modulus (DM) test were conducted to evaluate the strength and stiffness, and thermal conductivity tests and electrical conductivity evaluations were conducted for determining the functionality of the graphene-modified asphalt mixtures. The thermal conduction test was used to measure the external temperature change over time by placing a general heated asphalt mixture and graphene-modified asphalt with the same raw material-specific mixing ratio inside the temperature chamber in order to measure the heat conductivity. The electrical conductivity was evaluated using a digital multimeter to measure the resistance of DC voltage and DC current via a 4-probe method. RESULTS : The performance grade (PG) test results showed that, for a dynamic shear rheometer (DSR), both tests met the baseline and that physical changes in the binder did not appear evident with graphene addition. Furthermore, each content met the baseline for the bending beam rheometer (BBR). The increasing ratio of flexural creep stiffness approached the maximum when 7.5% graphene was used. In indirect tensile strength test, an average of thrice the indirect tensile strength for graphene-modified asphalt was 0.92 N/mm2, which was approximately 0.04 N/mm2 higher than the average measured three times that of hot mix asphalt mixture, with the same raw material mixing ratio. In the thermal conduction tests, the temperature and the rate of change of temperature of the graphene-modified asphalt mixture were higher than those of the hot-mix asphalt mixture. Lastly, the results of the electric conductivity test using the 4-probe method showed that the electrical conductivity increased slightly as the graphene content increased, but overall, it showed very low electrical conductivity. CONCLUSIONS : In this study, the potential for enhancing the physical and functional performance of graphene nanoplates applied to asphalt mixtures was demonstrated. However, it is practically difficult to arrange graphene particles continuously within an asphalt mixture, which is believed to have very low electrical conductivity.
그라운드 앵커 긴장재 손상 검출을 위한 FE 시뮬레이션 기반 EM(Elasto-Magnetic) 센서 설계 및 검증
고동영 ( Ko¸ Dongyoung ),박주영 ( Park¸ Jooyoung ),이창준 ( Lee¸ Changjun ),김승우 ( Kim¸ Seung Woo ),박승희 ( Park¸ Seunghee ) 한국구조물진단유지관리공학회 2023 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.27 No.2
A design process considering the electromagnetic characteristics of the materials and target object is essential for fabricating an EM(Elasto-Magnetic) sensor. However, several studies have not considered this. Therefore, in this study, the sensor parameters were initially determined through a finite element (FE) simulation, considering the size and form of an actual ground anchor. Subsequently, an indoor experiment was performed to verify the possibility of detecting tendon damage using a fabricated EM sensor by measuring the electromotive force (EMF). Finally, the experiment results were compared with the FE simulation results.