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양성린,임정혁,황성도,백철민,Yang, Sung Lin,Im, Jeong Hyuk,Hwang, Sung Do,Baek, Cheolmin 한국도로학회 2015 한국도로학회논문집 Vol.17 No.4
PURPOSES : The objective of this study is to evaluate the SDAR (solvent deasphaltene residue), which is obtained from the solvent deasphalting (SDA) process, as a pavement material. METHODS : The physical properties of the SDAR were evaluated based on its chemical composition, and asphalt mixtures with the SDAR were fabricated and used for the evaluation of mechanical properties. Firstly, the chemical composition of SARA (saturate, aromatic, resin and asphaltene) was analyzed using the TLC-FID (thin-layer chromatography-flame ionization detector). Moreover, the basic material properties of the asphalt binder with the SDAR were evaluated by the penetration test, softening point test, ductility test, and PG (performance grade) grade test. The rheological properties of the asphalt binder with the SDAR were evaluated by the dynamic shear modulus ($G^*$) obtained using the time-temperature superposition (TTS) principle. Secondly, the mechanical properties of the asphalt mixtures with the SDAR were evaluated. The compactibility was evaluated using the gyratory compacter. Moreover, the tensile strength ratio (TSR) was used for evaluating the moisture susceptibility of the asphalt mixtures (i.e., susceptibility to pothole damage). The dynamic modulus $E^*$, which is a fundamental property of the asphalt mixture, obtained at different temperatures and loading cycles, was used to evaluate the mechanical properties of the asphalt mixtures. RESULTS AND CONCLUSION : The SDAR shows stiffer and more brittle behavior than the conventional asphalt binder. As the application of the SDAR directly in the field may cause early failures, such as cracks on pavements, it should be applied with modifiers that can favorably modify the brittleness property of the SDAR. Therefore, if appropriate additives are applied on the SDAR, it can be used as a pavement material because of its low cost and strong resistance to rutting.
Laboratory Performance Evaluation of Recycled Asphalt Binders with Differing Rejuvenators
김영민,임정혁,황성도,정규동,이석근,Kim, Yeong Min,Im, Jeong Hyuk,Hwang, Sung Do,Jeong, Kyu Dong,Rhee, Suk Keun Korean Society of Road Engineers 2015 한국도로학회논문집 Vol.17 No.6
PURPOSES : The objective of this study is to investigate the properties of recycled asphalt binders with five different rejuvenators, in order to evaluate the applicability of the recycled asphalt binders compared with the original asphalt binder. METHODS : In order to simulate recycled asphalt binders, fresh asphalt binders are aged by various Superpave aging procedures, such as the rolling thin-film oven (RTFO) and the pressure aging vessel (PAV). Then, selected rejuvenators are added to the aged asphalt binders in the amount of 5%, 10%, and 15%. The asphalt binder properties are evaluated by the dynamic shear rheometer (DSR), the rotational viscometer (RV), and the bending beam rheometer (BBR). In this study, AP-5 (penetration grade 60-80, PG 64-16) asphalt binder is used. A total of five types of rejuvenators are employed. RESULTS AND CONCLUSIONS : When considering aged asphalt without a new asphalt binder, it seems that the percentage of rejuvenator used in Korea is a bit too low, and that it fails to possess the characteristics of the original binder. From the current practice of evaluating the properties of recycled binder based on penetration ratio only, the amount of rejuvenator required is similar for the long-term-aged binder, but is excessive for the longest-term aged binder, causing deterioration of workability and stiffness of the recycled binder.
서영국(Seo Youngguk),백철민(Bak Chul-Min),김영수(Kim Y. Richard),임정혁(Im Jeong-Hyuk) 대한토목학회 2008 대한토목학회논문집 D Vol.28 No.6D
이동하중에 의한 아스팔트 포장의 변형률과 피로수명을 예측할 수 있는 유한요소해석 프로그램을 개발하고 그 성능을 현장 및 가속시험의 계측결과로 검증하였다. 본 논문에서는 아스팔트 혼합물의 점탄성 연속체 손상(ViscoElastic Continuum Damage, VECD)모형을 유한요소해석 프로그램인 VECD-FEP++(Finite Element Program in C++)로 구현하는 과정을 다 루고 있다. 아스팔트 혼합물의 피로손상은 열역학 이론에 근거한 Schapery의 일 포텐셜 이론(work potential theory)과 일축 단일 변형률 인장 시험으로 정의하고 이를 VECD 모형의 입력변수로 사용하였다. 실제 포장의 동적 변형률을 예측하기 위하여 한국도로공사 시험도로에서 이동하중 시험을 실시하고 그 결과를 비교하였다. 또한 4가지 서로 다른 아스팔트 혼합물(일반밀입도, SBS, Terpolymer, CR-TB)을 사용한 포장가속시험을 실시하고 각각의 피로 특성을 유한요소해석으로 예측하였다. 아스팔트 기층상부와 기층하부에서의 횡방향 변형률은 계측과 수치해석결과가 잘 일치하였다. 반면에, 표층과 중간층에 서의 응답은 차량접지하중의 복잡한 영향으로 인하여 이를 반영할 수 없는 현재의 유한요소해석모델의 예측결과와는 다소 차이가 있었다. 포장가속시험결과 SBS 혼합물의 피로저항능력이 가장 우수한 것으로 평가 되었으나 VECD-FEP++에 의한 수명은 이와는 다르게 Terpolymer가 가장 우수한 것으로 예측되었다. This paper deals with the development of ViscoElastic Continuum Damage Finite Element Program (VECD-FEP++) and its verification with the results from both field and laboratory accelerated pavement tests. Damage characteristics of asphalt concrete mixture have been defined by Schapery's work potential theory, and uniaxial constant crosshead rate tests were carried out to be used for damage model implementation. VECD-FEPH predictions were compared with strain responses (longitudinal and transverse strains) under moving wheel loads running at different constant speeds. To this end, an asphalt pavement section (AS) of Korea Expressway Corporation Test Road (KECTR) instrumented with strain gauges were loaded with a dump truck. Also, a series of accelerated pavement fatigue tests have been conducted at pavement sections surfaced with four asphalt concrete mixtures (Dense-graded, SBS, Terpolymer, CR-TB). Planar strain responses were in good agreement with field measurements at base layers, whereas strains at both surface and intermediate layers were found different from simulation results due to the complexity of tire-road contact pressures. Finally, fatigue characteristics of four asphalt mixtures were reasonably described with VECD-FEP++.