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        41.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        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.
        4,000원
        42.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In this study, we aimed to investigate the heat transfer characteristics of asphalt mixtures by water saturation. METHODS : On the basis of the literature review, the heat transfer characteristics of the samples were analyzed using a thermal accumulation experiment. The types of samples used were WC2 (dense asphalt mixture), ReWC2 (used 30% recycled aggregate), and PA13 (drainage asphalt mixture). The samples were compacted using a gyratory compactor. An infrared lamp simulating insolation was used to continuously heat the asphalt sample. Through this experiment, the upper and lower temperatures and heat flux of the specimen according to its thickness and condition were measured, and the change in its thermal conductivity was analyzed. RESULTS : The results of the laboratory experiment indicated that the dry sample showed lower thermal conductivity than the saturated sample. The amount of evaporation varied depending on the internal pores of the sample. Additionally, the amount of evaporation changed the heat transfer characteristics of the specimen. CONCLUSIONS : An asphalt mixture with high porosity decreased the degree of increase in thermal conductivity, compared to mixtures with low porosity, under semi-saturated conditions; this was attributed to the difference in thermal conductivity between air and water during saturation. The results of this study on the heat transfer characteristics of asphalt pavements could be used as basic data for thermal energy harvesting of asphalt pavements.
        4,000원
        43.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study was to evaluate newly developed Guss mastic asphalt with polymer modifier as a elastomer and a plastomer in to polymer content. METHODS : As polymer modifiers, 10%, 20% of elastomer and 10%, 20% of plastomer, and 10% of elastomer and 10% of plastomer are all added to the binder, and the physical properties of the Guss mastic asphalt mixture with these binders are changed. The properties of mixtures with workability, penetration depth and dynamic stability were compared with the existing Guss mastic asphalt mixture. RESULTS : When using the elastomer and the plastomer, the dynamic stability of the Guss mastic asphalt mixture was improved compared to the conventional asphalt mixture, and when the amount of the elastomer was 20%, the workability was reduced. In addition, when 10% of the elastomer and 10% of the plastomer were used, the workability was not significantly deteriorated and the dynamic stability was increased. CONCLUSIONS : In order to improve the dynamic stability of the Guss mastic asphalt mixture using the polymer-modified binder, it is effective to use an elastomer and a plaststomer.
        4,000원
        44.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This study aims to develop drainage minor-structure materials using asphalt mixtures, and to apply construction methods. METHODS : The AP-5, 120-150A, and 150-200A binders were adopted to select the optimal asphalt binder for the domestic application of asphalt concrete in curb construction. The mixture design of asphalt mixtures has applied the standard for evaluating asphalt curb mixtures in Korea. Test construction utilized asphalt curb equipment to evaluate asphalt mixtures, according to the type of asphalt binder. RESULTS : The results of the asphalt mixture design indicated that the optimum asphalt content was determined at 2–3% air void for each type of asphalt binder, and the quality of the asphalt mixture applied with asphalt curb binder was excellent. In addition, the quality difference was significant, depending on the temperature of the asphalt mixture at each phase of the asphalt curb construction. CONCLUSIONS : Asphalt curb construction using asphalt materials has a large impact on the quality, depending on the temperature of the asphalt mixture, therefore management at the appropriate temperature is important when applying it to the site. Further research is also required on the production, transportation, and dedicated equipment of asphalt mixtures.
        4,000원
        45.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study was to evaluate the newly developed Guss mastic asphalt mixtures, called EQ-mastic asphalt mixtures, which contain melted additives for decreasing cooking time. METHODS : A series of experiments were performed to investigate the effectiveness of the melted additives in EQ-mastic asphalt mixtures. Both the existing Guss mastic asphalt mixture and the EQ-mastic asphalt mixture were produced with the same amounts of asphalt binders, aggregates, and fillers, but the existing Guss mastic asphalt mixture contained 3% Trinidad lake asphalt (TLA). The EQ-mastic asphalt mixture contained 3% of additives, including TLA and polyolefin. The physical material performances of both mastic asphalt mixtures were obtained by conducting the Luer fluidity test, penetration test, dynamic stability test, and low-temperature bending test. The results of the tests for the existing Guss mastic and EQ-mastic asphalt mixtures were compared. RESULTS : The fluidity, penetration, dynamic stability, and low-temperature bending strains of both the existing Guss mastic and EQmastic asphalt mixtures all satisfied the standard values provided in the production and construction guides of the Guss mastic asphalt pavement. CONCLUSIONS : When melted additives containing polyolefin are used in the production of Guss mastic asphalt mixtures, the cooking time decreases, so that the corresponding energy consumption and asphalt fume amount can be reduced. Therefore, an EQ-mastic asphalt mixture is proposed for use as an eco-friendly pavement material.
        4,000원
        48.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The objective of this study is to quantitatively evaluate the visibility of a mixed-color asphalt pavement. METHODS : The visibility was compared and evaluated using a color pavement specimen, i.e., a pigment was added to the asphalt binder, which was used to fabricate a color pavement specimen, with red aggregate as the coarse aggregate, and the resultant difference in visibility was quantitively evaluated. The color asphalt mixture to which the pigment was added was prepared by varying the amount of pigment added — i.e., 3 %, 5 %, and 7 % of the total weight of the mixture — to confirm the change in visibility according to the amount of pigment added. For the color asphalt mixture with color aggregates, red-colored mudstone coarse aggregates(13mm and 10mm) were used. It is assumed that the surface of the produced specimen simulates the initial performance periods and the cut section of the specimen simulates the state of completion of the performance periods. RESULTS : The initial ΔE for the colored pavement exhibited the best visibility of WC-2-R. However, when considering the value of a in the red color pavement, the visibility of SMA13-R and WC-2-R was assessed as best; this is because SMA13-R exhibits a lower color difference than WC-2-R at the beginning of the performance periods but the red color is better. Upon completion of the colored pavement performance periods, the ΔE of each specimen using the SMA13-0C specimen as the reference specimen was high in SMA13-RC and ΔE using the WC-2-0C specimen as the reference specimen was also high in SMA13-RC. In addition, the a value is also higher than that of other mixtures so it is judged that the visibility of SMA13-RC is best when the performance periods are completed. CONCLUSIONS : The a value tended to increase with the increasing amount of pigment added at the beginning of the performance; however, it was found to decrease rapidly as the performance was completed. However, in the case of using SMA13-RC as the colored aggregate, since the color of the aggregate itself is red, it exhibits a constant value of 5.67 from the performance start to completion. Therefore, it is judged that a constant red color can be expressed during the performance period when the colored pavement using red colored aggregate is applied to the exclusive bus lane.
        4,000원
        49.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The cooling characteristics of the asphalt mixture in a moving dump truck were analyzed using a numerical simulation method. The cooling characteristic can be used to determine the optimum transport path for minimizing the temperature drop of the asphalt mixture. METHODS : In this research, a coupled analysis of the discrete element method (DEM) with computational fluid dynamics (CFD) was applied for cooling characteristic analysis of asphalt mixtures in transit. Two different transit speeds, 30 km/h and 60 km/h, were considered to evaluate the effect of speed on the temperature drop of the asphalt mixture. Velocity, pressure, and temperature contours were plotted and temperature variations were compared. RESULTS : Most of the temperature drops in the asphalt mixture were observed in the middle of the dump box in the longitudinal direction. It was confirmed that a faster speed causes a greater temperature drop for the same travel time and a slower speed causes the more temperature to reach the same travel distance as expected. CONCLUSIONS : It is concluded that the coupled analysis method can be used to quantitatively evaluate the effect of vehicle speed on temperature drop in asphalt mixtures. In addition, the method can be used to determine the optimum travel path considering environmental conditions and traffic congestion.
        4,000원
        50.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : This paper presents a quality evaluation of Korean foamed asphalt, which uses the maximum expansion ratio and half-life method. The maximum expansion ratio and half-life method are used to determine the optimum water content to produce a foamed asphalt mixture. The foamed asphalt mixture according to determine an optimum water content with this method; the mixture quality was compared with hot mix asphalt mixture. METHODS : For the foamed asphalt mixed design, the water content was determined in addition to the Marshall mixing design method. The water content was determined using the ratio of the maximum to minimum volume and the time for the volume to decrease to half of the maximum volume. We conducted stability, indirect tensile strength, tensile strength ratio, dynamic immersion, and absorption rate tests to compare the foamed and hot mixed asphalt mixtures. RESULTS : The foam asphalt mixture exhibited less performance reduction due to temperature change than the hot mixed asphalt mixture. Most of the two mixture types exhibited similar performance. In addition, both mixtures should use an anti-stripping agent to improve water resistance. CONCLUSIONS : As a result of the laboratory test, the foamed asphalt mixture was able to ensure a similar performance to the hot-mixed asphalt mixture.
        4,000원
        51.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study is to analyze the effect of ions in emulsion asphalt on recycling cold asphalt concrete and suggest the possibility of using anionic and nonionic emulsion asphalt. METHODS : In this study, indirect tensile strength, toughness, tensile strength ratio, and dynamic immersion tests were conducted to determine the effects of cation, anion, and non-ion emulsified asphalt on the cold recycled asphalt mixture. Crack resistance was evaluated through indirect tensile strength and toughness tests and the tensile strength ratio and dynamic immersion test were evaluated through tensile strength ratio and dynamic water immersion test. RESULTS : Indirect tensile strength and toughness measurement results demonstrated that the mixture using anion and non-ion emulsified asphalt tended to be higher than that using cation emulsified asphalt; this is due to the high content of reclaimed asphalt pavement with a cationic or ionic surface, which is related to the use of cation-emulsified asphalt in the mixture and has shown a low strength tendency. The tensile strength ratio measurement demonstrated that the mixture using non-ion emulsified asphalt tended to be approximately 15 % higher than that of the anion mixture. This demonstrated that the chemical additive used in the mixture showed a complete hydration reaction with the distribution to the mixture. The dynamic immersion test indicates that the aggregate film rate of asphalt is highly influenced by the surface electric charge of the new aggregate while the ionicity effect appears to be insignificant, at 75 - 85 %, when circular aggregates are used. CONCLUSIONS : High reclaimed asphalt pavement content in cold recycled asphalt mixture, as well as non-ion and anionic emulsified asphalt, is advantageous, reducing cracking and improving moisture resistance. It is believed that anions and non-ions may be better utilized than applying the existing criteria to the cold temperature recycled asphalt mixture with high reclaimed asphalt pavement content. In addition, if the scope of the emulsified asphalt is expanded, various additives can be used, which will require analysis of materials, such as fertilizers and additives.
        4,000원
        52.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The objective of this study is to address various problems, such as an increase in material cost and premature failure (e.g., cracks and potholes) of porous pavements, and to develop multifunctional asphalt and asphalt mixtures to ensure the long-term commonality of porous asphalt pavements. METHODS : A basic quality test of two types of porous asphalt mixtures was performed. One type consisted of the existing porous asphalt mixture, using domestically presented grading, and the other a porous asphalt mixture using high-viscosity modified asphalt with enhanced low-temperature properties, aimed at improving strain resistance and developed by applying the grading suggested by the Federal Highway Administration (FHWA). RESULTS : The cantabros loss rate was 19.62 % for conventional modified asphalt (PG 82-22) and 5.95 % for the developed highviscosity modified asphalt (PG 88-28), indicating that both mixtures passed the criteria. Regarding the drain-down loss rate, mixtures using both types of asphalt were found to pass all quality standards. The average permeability coefficients for each porous asphalt mixture were 0.023 and 0.018 and both types of porous asphalt mixtures satisfied the quality standard of 0.01 cm/s, as given by the Asphalt Concrete Pavement Guidelines of the Ministry of Land, Infrastructure, and Transport. CONCLUSIONS : As a result of the mix design of the two porous asphalt mixtures, the mixture developed in this study was found to be superior to the conventional porous asphalt mixture using conventional porous asphalt grading and modified asphalt.
        4,000원
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