• International Journal of Highway Engineering
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• v.13 no.2
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• pp.41-48
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• 2011

Warm-mix asphalt(WMA) technology has been developed to allow asphalt mixtures to be produced and compacted at a significantly lower temperature. The WMA technology was identified as one of means to lower emissions for $CO_2$ and has been spread so quickly in the world. Recently, two innovative WMA additives has been developed to reduce mixing and paving temperatures applied in asphalt paving process in Korea. Since the first public demonstration project in 2008, many WMA projects have successfully been constructed in national highways. In 2010, the WMA field trial was conducted on new national highway construction under Dae-Jeon Regional Construction Management Administration. The two different WMA loose mixtures(WMA and WMA-P) and a HMA mixture were collected at the asphalt plant to evaluate their mechanical performance in the laboratory. The Third-scale Model Mobile Loading Simulator(MMLS3) was adopted to evaluate rutting resistance and moisture damage under different traffic and environmental conditions. In this study, plant-produced WMA mixtures using two WMA additives along with the conventional hot mix asphalt(HMA) mixtures were evaluated with respect to their rutting resistance and moisture susceptibility using MMLS3. Based on the limited laboratory test results, plant-produced WMA mixtures are superior to HMA mixtures in rutting resistance and the moisture susceptibility. The WMA additive was effective for producing and compacting the mixture at $30^{\circ}C$ lower than the temperature for the HMA mixture.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.79-86
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• 2010

Cold in-place recycling (CIR) using emulsified asphalt or foamed asphalt has become a more common practice in rehabilitating the existing asphalt pavement due to its cost effectiveness and the conservation of paving materials. As CIR continues to evolve, the engineered emulsified asphalt was developed to improve the field performances such as coating, raveling, retained stability value and curing time. The main objective of this research is to compare the laboratory responses of the engineered emulsified asphalt (CIR-EE) mixtures against the foamed asphalt (CIR-foam) mixtures using the reclaimed asphalt pavement (RAP)materials collected from the CIR project on U.S. 20 Highway in Iowa. Based on the visual observation of laboratory specimens, the engineered emulsified asphalt coated the RAP materials better than the foamed asphalt because the foamed asphalt is to create a mastic mixture structure rather than coating RAP materials. Given the same compaction effort, CIR-EE specimens exhibited lesser density than CIR-foam specimens. Both Marshall stability and indirect tensile strength of CIR-EE specimens were about same as those of CIR-foam specimens. However, Marshall stability and indirect tensile strength of the vacuum-saturated wet specimens of CIR-EE mixtures were higher than those of CIR-foam mixtures. After four hours of curing in the room temperature, the CIR-EE specimens showed less raveling than the CIR-foam specimens. On the basis of test results, it can be concluded that the CIR-EE mixtures is less susceptible to moisture and more raveling resistant than CIR-foam mixtures.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.19-29
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• 2008

To produce asphalt mixtures at temperature significantly below $135^{\circ}C$, called "Warm Mix Asphalt (WMA)", new technologies are currently being developed worldwide. To produce WMA mixtures in this research, foaming technology is adopted to effectively disperse asphalt binder at lower temperature than hot mix asphalt (HMA) in the field. The main objectives of this study are to develop WMA process using foaming technology (WMA-foam) and evaluate its performance characteristics under various temperatures and loading conditions. WMA-foam mixtures were produced by injecting PO 64-22 foamed asphalt into warm aggregates whereas WMA mixtures were produced by adding PO 64-22 asphalt (without foaming) in the warm aggregates. Both dynamic modulus and flow number of WMA-foam mixtures were higher than those of WMA mixtures. Based on the limited dynamic modulus and repeated load test results, it is concluded that the WMA-foam mixtures using warm aggregates at $100^{\circ}C$ are more resistant to fatigue cracking and rutting than WMA mixtures.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.149-158
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• 2007

Evaluation of the asphalt mixture modified with crumb rubber modifier(CRM) was performed to estimate possibility of using it as a paying material. OACs(optimum asphalt content) of CRM modified asphalt mixtures by dry process and wet process were determined by Marshall mix design and Wheel tracking test and moisture susceptibility test by freezing and thawing were carried out with CRM modified asphalt mixtures at OACs. The results from these tests, resistance of permanent deformation of CRM modified asphalt mixtures were superior to one of AP-5 while showing very low resistance of moisture sensitivity by freezing and thawing. This means that CRM modified asphalt mixtures are very sensitive to freezing and thawing. However, CRM modified asphalt mixture with anti-stripping material showed high improvement to resistance of moisture susceptibility by freezing and thawing. Therefore, it is recommended that when CRM mixtures were used in domestic, CRM modified asphalt mixtures should be with prevention against freezing and thawing resistance by moisture susceptibility.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.582-590
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• 1995

우리 나라에서 건설될 중저준위폐기물 처분장의 기본설계개념에 따르면, 중준위폐기물 동굴에는 점토질 뒷채움재가 설치될 예정이다. 이 뒷채움재의 후보물질로는 원료 입수의 용이성 및 경제성 측면에서 천연점토와 분쇄암석의 혼합물이 고려되고 있다. 그러나 이 혼합물이 폐기물처분장의 뒷채움재로 사용되기 위해서는 주요특성들이 뒷채움재의 요구사항을 만족시켜야한다. 이 보고서에서는 경상북도 연일지역에서 산출되는 천연점토와 분쇄암석 혼합물에 대해 핵종유출저지 관점에서 가장 중요한 특성인 수리특성과 방사성핵종 확산특성 및 역학적 특성을 측정하여 뒷채움재료로서의 사용 가능성을 평가하였다. 혼합물의 수리전도도는 동일 밀도에서 점토함량이 감소함에 따라 증가되었으나, 점토함량이 적은 경우에도 상당히 낮은 값을 유지하여 뒷채움재를 통한 핵종이동의 주요 메커니즘은 확산이 될 것이라는 것을 보여주었다. 압축점토에 대한 방사성핵종 복산계수 측정결과, 동일밀도의 나트륨벤토나이트에서 측정된 값의 범위 내에 있었으며, 점토-분쇄암석 혼합물의 액소성한계, 다짐특성, 압축강도및 압밀계수등의 역학적 특성도 나트륨벤토나이트-모래 혼합물에서 얻어진 값과 유사하였다. 이러한 결과들로부터 연일산 천연점토-분채암석 혼합물을 고가의 나트륨벤토나이트 대용으로 처분장 뒷채움재로 사용할 수 있다는 것을 알 수 있었다.

• 한국도로학회지:도로
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• v.2 no.4 s.6
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• pp.37-49
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• 2000

이 보고서는 수퍼페이브의 개념으로 설계된 혼합물이 시방규정에 만족하기 위하여 꼭 필요한 혼합물의 생산, 포설 및 다짐에 대한 내용을 정리한 것이다. 이 보고서 단독으로는 큰 의미가 없으며, 기존의 일반적인 혼합물에 사용되었던 훌륭한 시공기술이 동시에 사용되어야한다. 수퍼페이브가 적용됨으로 해서 발생되는 혼합물의 가장 큰 변화는 굵은입도의 혼합물사용 및 보다 많은 양의 모난골재사용 그리고 개질아스팔트의 사용 등이다. 이러한 변화들은 약간의 시공순서의 수정을 필요로 하게 된다. 이 보고서는 이러한 것에 대한 몇 가지 제안을 포함하고 있다.

• International Journal of Highway Engineering
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• v.3 no.3 s.9
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• pp.119-133
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• 2001

The stiffness of chemcrete modified asphalt mixtures increase rapidly with time in the presence f oxygen and high temperature, Sometimes the asphalt pavements that have chemcrete modified asphalt mixture applied on the surface none show premature cracking because of the excessive increase in the stiffness f the asphalt mixtures. To mitigate this premature cracking, the chemcrete modified mixtures have been used as a base course material. In this study, the performance of the chemcrete modified asphalt binder and mixtures are investigated through a course of various laboratory tests including dynamic shear rheometer and bending beam rheometer tests for binders and uniaxial tensile fatigue, wheel tracking, and moisture damage tests for the mixtures. And also the resilient modulus of the conventional and chemcrete modified mixtures are compared based on the test results conducted on the specimens obtained from various in-situ test sections. It can be concluded from the tests results that the chemcrete modified mixtures show better rutting resistance than conventional mixtures. The chemcrete modified mixtures may have low temperature cracking when it is applied in the cold region. The stiffness of chemcrete modified mixtures is approximately 50 percent higher than that of conventional mixtures more than two years after the chemcrete modified mixture was applied in the base course.

• Resources Recycling
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• v.7 no.2
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• pp.53-58
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• 1998

Wheel tracking and ravelling tests were conducted on the hot mix crumb rubber modified asphalt concrete usmg waste tire t to evaluate the mechanical prope$\pi$ies in comparison with conventional asphalt concrete. According to the test results, the m modified product, lias superior to the conventional one by 50% in the resistance of permanent deformation and by 15% in the m resistance of dmability. The experimental results should recommend thut the waste tir$\xi$ is positively recycled for asphak concrete.

• Journal of the Society of Disaster Information
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• v.7 no.1
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• pp.32-42
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• 2011

Many researches have been conducted to evaluate the performance of modified asphalt concrete mixtures. The research was conducted to estimate the laboratory mechanical characteristics of Elvaloy-modified asphalt concrete mixture. To achieve its intended objective, indirect tensile test and resilient modulus test were performed. The rest results revealed that indirect tensile strengths and resilient moduli of the Elvaloy-modified asphalt concrete mixture were higher than those of the conventional dense-graded. As a result, within the limits of the tests conducted in this research, it is predicted that the performance and stability of the Elvaloy-modified asphalt concrete mixture are better than that of the conventional dense-graded one.

• International Journal of Highway Engineering
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• v.5 no.2 s.16
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• pp.1-14
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• 2003

This study is a fundamental research for developing self-deicing function of snow-melting asphalt concrete for roadway pavement. The objective of this study is to develop technology of making self-snow-melting asphalt pavement and evaluate properties of the asphalt concrete containing deicers. Asphalt concrete with deicers and CRM was produced by dry process. The $\alpha$-deicer, CRM and F-deicer were used for sand asphalt mixtures of thin-layer pavement on the existing pavement. The $\alpha$-deicer, $\beta$-deicer, CRM A, CRM B and C were used for 13mm dense-graded mixtures on surface course. Penetration grade of 60-80 asphalt was used for asphalt mixtures. Marshall mix-design, indirect tensile strength, freezing and thawing test, analysis of extracted water were carried out to evaluate performance of self deicing function of asphalt mixtures. The study result showed that snow-melting asphalt mixtures had not only good mechanical characteristics and good snow-melting function, but also chemically safe in environmental point of view.