• 대한토목학회논문집
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• 제37권2호
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• pp.497-505
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• 2017

TDF (Tire derived fuel) Fly ash는 폐타이어를 발전소의 연료원으로써 사용하고 발생된 분말형태의 산업 부산물이다. TDF Fly ash는 현재까지 국내에서 사업장 폐기물로 분류되어 적절하게 활용되지 못하고 있다. 새로운 활용 방안 모색을 위해 TDF Fly ash를 아스팔트 혼합물용 채움재(Mineral filler)로써 적용하여 사용 가능성을 알아보는 아스팔트 혼합물 기초 물성 시험을 실시하였다. TDF Fly ash는 국내 KS F 3501의 아스팔트 혼합물 채움재 기준을 만족하였으며 마샬 배합설계를 진행하여 4.5%최적아스팔트함량을 결정하였다. 채움재 함량은 3%로 결정하였으며 채움재로써 석분을 사용하여 비교 분석 하였다. 아스팔트 혼합물 기초 물성 시험은 국토교통부에서 발간한 "아스팔트 혼합물 생산 및 시공지침"에서 제시된 규정으로 평가하였다. 시험은 마샬안정도 시험, 동적수침 시험, 인장강도비 시험, 휠 트랙킹 시험을 실시하였다. 실험결과, 마샬안정도와 동적안정도는 국토교통부에서 제시된 기준에 만족하여 안정성을 확인하였고 동적수침과 인장강도비 시험은 TDF Fly ash가 석분보다 박리저항성 및 수분저항성에 효과가 있음을 확인하였다. 따라서 본 연구에서는 TDF Fly ash의 다각적 활용이 예상 되며 긍정적인 효과를 기대할 수 있을 것으로 판단된다.

• 한국도로학회논문집
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• 제18권4호
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• pp.29-35
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• 2016

PURPOSES : The new waste management policy of South Korea encourages the recycling of waste materials. One material being recycled currently is tire-derived fuel (TDF) ash. TDF is composed of shredded scrap tires and is used as fuel in power plants and industrials plants, resulting in TDF ash, which has a chemical composition similar to that of the fly ash produced from coal. The purpose of this study was to evaluate the properties of an asphalt concrete mix that used TDF ash as the mineral filler. METHODS : The properties of the asphalt concrete were evaluated for different mineral filler types and contents using various measurement techniques. The fundamental physical properties of the asphalt concrete specimens such as their gradation and antistripping characteristics were measured in accordance with the KS F 3501 standard. The Marshall stability test was performed to measure the maximum load that could be supported by the specimens. The wheel tracking test was used to evaluate the rutting resistance. To investigate the moisture susceptibility of the specimens, dynamic immersion and tensile strength ratio (TSR) measurements were performed. RESULTS : The test results showed that the asphalt concrete containing TDF ash satisfied all the criteria listed in the Guide for Production and Construction of Asphalt Mixtures (Ministry of Land, Infrastructure and Transport, South Korea). In addition, TDF ash exhibited better performance than that of portland cement. The Marshall stability of the asphalt concrete with TDF ash was higher than 7500 N. Further, its dynamic stability was also higher than that listed in the guide. The results of the dynamic water immersion and the TSR showed that TDF ash shows better moisture resistance than does portland cement. CONCLUSIONS : TDF ash can be effectively recycled by being used as a mineral filler in asphalt, as it exhibits desirable physical properties. The optimal TDF ash content in asphalt concrete based on this study was determined to be 5%. In future works, the research team will compare the characteristics of asphalt concrete as function of the mineral filler types.

• 한국지반공학회논문집
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• 제19권5호
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• pp.189-197
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• 2003

건설공사에서 발생되는 건설잔토는 처리 및 운반에 소요되는 비용이 고가이기 때문에 현장에서 재활용하기 위한 공법의 개발이 오래 전부터 요구되어 왔다. 본 연구는 현장에서 발생하는 토사를 아스팔트에 혼합하여 제조된 아스팔트 안정처리토의 역학적 특성을 평가하기 위한 실내시험 연구이다. 아스팔트와 토사의 혼합은 폼드(foamed)장치라고 불리는 장치를 사용하여 아스팔트에 거품을 발생시켜 토사와 혼합하는 방법을 사용하였다. 아스팔트가 토사와 혼합되었을 때 성능 향상을 조사하기 위해서 마샬안정도, 간접인장강도, 회복탄성계수, 크리프 시험 및 비압밀 비배수 삼축압축시험을 실시하였으며 조건을 달리하여 제작한 시료(일반토사, 시멘트 2% 보강 토사)와 결과를 비교 분석하였다. 시험 결과 아스팔트의 혼입은 안정도, 회복탄성계수, 수분저항성이 향상되는 것으로 나타났으며 시멘트의 첨가는 이러한 역학적 성능을 더욱 크게 향상시키는 것으로 나타났다. 아스팔트 안정토는 토사의 혼합 함수비, 습윤상태는 시험 결과에 영향을 미치는 것이 확인되었는데 배합 설계시 혼합함수비, 세립분의 량을 조절함으로써 아스팔트 안정토의 역학적 특성을 향상시킬 수 있는 것으로 발견되었다.

• 한국도로학회논문집
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• 제16권4호
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• pp.21-33
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• 2014

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.37-41
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• 2021

This study aims to investigate the relationship between the exchange rate and Trade Balance. Trade Balance is used as the dependent variable, and the independent variables are Exchange Rate, Gross Domestic Product, and Inflation. Augmented Dickey-Fuller unit root test was adopted to test the stationary property of time series data, Auto Regressive Distributed Lag model was employed to find the long run and short-run relationship and long-run adjustment, Bound test approach, the unrestricted Error Correction Model and Granger Causality Test are used to analyze the data from 1977 to 2019. The research findings suggest that inflation has a positive impact on the trade balance in the short run. The exchange rate and the Gross Domestic Product have adverse effects on Trade balance in the long run. The coefficient of ER in the previous year is negative, and the coefficient of TB in the previous year is positive and significant. This is consistent with the J-Curve phenomenon, which states that devaluation may not improve trade balance in the immediate period, but will significantly impact the trade balance improvement in subsequent periods. Hence Marshall Lerner Condition exists in Sri Lanka.

• Advances in concrete construction
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• 제10권6호
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• pp.515-526
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• 2020

Cold-mixed asphalt mixture is a widely recommended asphalt pavement materials with potentially economic and environmental benefits. Due to the reduction of natural non-renewable mineral resources, powder minerals with similar properties are considered as new mineral fillers in asphalt mixtures. This study explored the feasibility of using cement to replace natural limestone powder (LP) in emulsified asphalt concrete modified by styrene-butadiene styrene copolymer. The experimental tests, including compressive strength, Marshall stability as well as moisture susceptibility test, were used to investigate the mechanical properties, the Marshall stability, flow value, as well as the moisture damage. In addition, the influence of material composition on the performance of asphalt concrete is explained by the microstructure evolution of the pore structure, the interface transition zone (ITZ), and the micromorphology. Due to mineralogical reactivity of cement, its replacement part of LP improved the mechanical properties, Marshall stability, but it will reduce the moisture susceptibility and flow value. This is because with the increase of the cement substitution rate, the pore structure of the asphalt concrete is refined, the width of ITZ becomes smaller, and the microstructure is more compact. In addition, asphalt concrete with a larger nominal particle size (AC-16) has relatively better performance.

• 한국도로학회논문집
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• 제8권2호
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• pp.23-30
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• 2006

상온아스팔트 혼합물은 생산공정이나 시공 중에 naphtha나 kerosene을 사용하는 컷백 아스팔트와 같이 환경오염물질을 생성하지 않고 골재와 아스팔트 바인더를 가열하지 않기 때문에 가열아스팔트 혼합물에 비하여 환경친화적이며 경제적이다. 그러나 일반적으로 상온아스팔트 혼합물은 가열아스팔트 혼합물에 비해 내구성이나 수분민감성에서 미흡한 점이 많다. 본 연구에서는 상온아스팔트의 수분민감성과 내구성을 증진시킬 수 있는 섬유보강 상온아스팔트 혼합물(FEAM)에 대한 평가를 하였다. 최적 유화아스팔트량(OEC), 최적함수량(OWC) 그리고 최적 섬유보강제 첨가량(OFC)를 결정하기 위해서 마샬배합설계를 수정 개발하였다. 최적의 섬유보강 상온아스팔트 혼합물과 일반 상온아스팔트 혼합물을 제작하여 마샬안정도 시험, 간접인장강도 시험 및 회복탄성계수 시험을 실시하였고 그 결과를 가열아스팔트 혼합물의 결과와 비교하였다. 결과로 FEAM과 EAM 모두 마샬배합설계 기준으로 중간 교통량에 충분한 것으로 판명되었다. 또한 섬유보강에 의하여 일반 상온아스팔트 혼합물의 수분민감성과 내구성이 증진하는 효과도 얻을 수 있는 것으로 판명되었다

• 한국도로학회논문집
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• 제18권2호
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• pp.61-71
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• 2016

PURPOSES: The objective of this study was to determine the optimum ratio of mix design, for a reclaimed asphalt pavement (RAP) content of 100%, for spray injection application. METHODS: A literature review revealed that spray injection is an efficient and cost-effective application for fixing small defective regions of an asphalt pavement. Rapid-setting polymer-modified asphalt mixtures prepared from two types of rapid-setting polymer asphalt emulsion were subjected to Marshall stability and wet track abrasion tests, in order to identify the optimum mix designs. RESULTS and CONCLUSIONS : Different mix designs of type A and type B emulsions were prepared using RAP and virgin aggregates, in order to compare the performance and determine the optimum mix design. The performance of mixtures prepared with RAP was superior to that of mixtures containing virgin aggregates. Moreover, for optimum ratio of the design, the binder content prepared from RAP was set to 1~2% lower than that consisting of virgin aggregates. Compared to their Type A counterparts, type B mixtures consisting of a reactive emulsion performed better in the Marshall stability and wet track abrasion tests. The initial results confirmed the advantages associated with using RAP for spray injection applications. Further studies will be performed to verify the difference in the optimum mix design and performance obtained in the lab-scale test and tests conducted at the job site by using the spray injection machine.

• 한국도로학회논문집
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• 제4권4호
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• pp.13-21
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• 2002

본 연구에서는 아스팔트 혼합물의 특성을 평가하는 대표적인 방법인 마샬안정도와 간접인장강도 시험시 양생온도와 양생시간 및 시험온도에서의 처리시간이 결과에 미치는 영향을 비교분석 하였다. 마샬안정도 시험은 공시체를 $60^{\circ}C$로 유지되는 수조에 30분 수침 후 수행하지만, 공시체의 양생시간에 관한 기준은 없다. 간접인장강도 시험의 경우는 시험온도는 $25^{\circ}C$라고 정해져 있지만 마샬안정도 시험과 마찬가지로 양생시간에 관한 기준은 없다. 또한 간접인장강도 시험을 하기 전 공시체의 온도를 $25^{\circ}C$로 맞추기 위하여 항온항습기 등과 같은 장치에 일정시간 보관해야 하는데 이것 역시 정해진 규정이 없다. 연구결과, 공시체의 양생온도에 따라 안정도와 간접인장강도 값은 많은 차이를 나타냈다. 따라서, 실험실 온도가 $25^{\circ}C$보다 높거나 낮으면, 혼합물의 양생이 제대로 되지 않아 시험결과의 신뢰성이 떨어질 것이다. 양생온도 변화에 따른 시험값 변화를 최소화하기 위하여. 마샬안정도 시험시 공시체를 $60^{\circ}C$ 수조에 수침해야 하는 시간과 간접인장강도 시험 전 공시체를 $25^{\circ}C$에 보관해야 하는 시간을 제안하였다.

• 한국도로학회논문집
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• 제19권2호
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• pp.75-85
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• 2017

PURPOSES : The purpose of this study was to determine the optimum mix design of the content of 100 % reclaimed asphalt pavement (RAP) for spray injection application with different binder types. METHODS : Literature review revealed that spray injection method is the one of the efficient and economical methods for repairing a small defective area on an asphalt pavement. The Rapid-Setting Polymer modified asphalt mixtures using two types of rapid setting polymers-asphalt emulsion and a quick setting polymer asphalt emulsion-were subjected to the following tests to determine optimum mix designs and for performance comparison: 1) Marshall stability test, 2) Retained stability test, 3) Wet track abrasion test, and 4) Dynamic stability test. RESULTS and CONCLUSIONS : Type A, B, and C emulsions were tested with different mix designs using RAP aggregates, to compare the performances and determine the optimum mix design. Performance of mixtures with Type A emulsion exceeded that of mixtures with Type B and C emulsion in all aspects. In particular, Type A binder demonstrated the highest performance for WTAT at low temperature. It demonstrated the practicality of using Type A mixture during the cold season. Furthers studies are to be performed to verify the optimum mix design for machine application. Differences in optimum mix designs for machine application and lab application will be corrected through field tests.