현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 반응특성 비교 Comparing Laboratory Responses of Engineered Emulsified Asphalt and Foamed Asphalt Mixtures for Cold In-place Recycling Pavement원문보기
일반적으로 유화 아스팔트와 폼드 아스팔트를 사용한 현장 상온 재생 아스팔트 포장은 노후한 아스팔트 포장을 재생하는데 가장 경제적이며 친환경적인 재활용 공법이다. 최근, 현장 상온 재생 아스팔트 혼합물의 코팅, 라벨링, 잔류안정도, 양생조건을 향상시켜주는 고점착 유화 아스팔트가 개발되었다. 본 연구의 목적은 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 실내시험에 대한 반응특성을 비교하는 것이다. 고점착 유화 아스팔트 혼합물은 폼드 아스팔트 혼합물과 비교하여 재활용 골재를 균일하게 코팅시켜주는 것으로 육안 관찰되었다. 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 마샬안정도와 간접인장강도는 유사한 반응을 보여주었다. 하지만 진공으로 포화된 습윤상태의 고점착 유화 아스팔트 혼합물의 마샬안정도와 간접인장강도는 폼드 아스팔트 혼합물보다 우수한 것으로 나타났다. 4시간 양생 후 고점착 유화 아스팔트 혼합물의 라벨링 현상은 폼드 아스팔트 혼합물보다 적게 발생하였다. 본 실내시험에 대한 반응특성으로부터 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물은 폼드 아스팔트 혼합물보다 우수한 저항성과 라벨링 저항성을 발휘하는 것으로 평가되었다.
일반적으로 유화 아스팔트와 폼드 아스팔트를 사용한 현장 상온 재생 아스팔트 포장은 노후한 아스팔트 포장을 재생하는데 가장 경제적이며 친환경적인 재활용 공법이다. 최근, 현장 상온 재생 아스팔트 혼합물의 코팅, 라벨링, 잔류안정도, 양생조건을 향상시켜주는 고점착 유화 아스팔트가 개발되었다. 본 연구의 목적은 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 실내시험에 대한 반응특성을 비교하는 것이다. 고점착 유화 아스팔트 혼합물은 폼드 아스팔트 혼합물과 비교하여 재활용 골재를 균일하게 코팅시켜주는 것으로 육안 관찰되었다. 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물과 폼드 아스팔트 혼합물의 마샬안정도와 간접인장강도는 유사한 반응을 보여주었다. 하지만 진공으로 포화된 습윤상태의 고점착 유화 아스팔트 혼합물의 마샬안정도와 간접인장강도는 폼드 아스팔트 혼합물보다 우수한 것으로 나타났다. 4시간 양생 후 고점착 유화 아스팔트 혼합물의 라벨링 현상은 폼드 아스팔트 혼합물보다 적게 발생하였다. 본 실내시험에 대한 반응특성으로부터 현장 상온 재생 아스팔트 포장을 위한 고점착 유화 아스팔트 혼합물은 폼드 아스팔트 혼합물보다 우수한 저항성과 라벨링 저항성을 발휘하는 것으로 평가되었다.
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 develop...
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.
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.
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문제 정의
Highway 20, at the east end of Highway 187 in Buchanan County, Iowa, was recycled using two different stabilizing agents in CIR: engineering emulsified asphalt called “ReFlex®”(CIR-EE) and foamed asphalt (CIR-foam). The primary objective of this research is to compare laboratory responses of CIR-EE mixtures against CIR-foam mixtures using RAP materials collected from U.S. Highway 20 in Iowa.
he main objective of this research is to compare the laboratory responses of CIR-EE against CIR-foam mixtures using RAP materials collected from the CIR project on U.S. 20 Highway in Iowa. Laboratory specimens were prepared using Marshall hammer and Superpave gyratory compactor to measure the fundamental material properties, which include 1) density, 2) Marshall stability, 3) indirect tensile strength, and 4) raveling resistance.
제안 방법
In the future, it is recommended that additional performance tests such dynamic modulus and repeated load tests should be performed. Since all tests were performed using only one RAP source, it is recommended that all tests should be repeated for various sources of RAP materials for a broader picture of the performance of the recycled pavements using the engineered emulsified asphalt or foamed asphalt.
The findings should be interpreted for such a condition only. The readers are cautioned not to extrapolate beyond the single point design with a restricted number of test temperatures. In the future, it is recommended that additional performance tests such dynamic modulus and repeated load tests should be performed.
The study was based on a single point design and one asphalt content for each. The findings should be interpreted for such a condition only.
To prepare the laboratory CIR specimens, as summarized in Table 1, the engineered emulsified asphalt and water contents were selected as 3.0% and 2.0%, respectively, by weight of the RAP materials. Given the residual asphalt content of 65% in engineered emulsified asphalt, 3.
A pugmill mixer (Figure 4(a)) was used for CIR-EE mixtures and standard bowl mixer (Figure 4(b)) was used for CIR-foam mixtures. To simulate the compactive efforts in the field, the following two compaction methods were used to prepare laboratory specimens of CIR-EE and CIR-foam mixtures: 50 blows of Marshall hammer and 30 gyrations of Superpave gyratory compactor.
대상 데이터
0% asphalt content. The base asphalt for the engineered emulsion was a PG 64-34. The foamed asphalt and water contents were selected as 2.
The reclaimed asphalt pavement(RAP) materials were collected from the westbound section of U.S. Highway 20, located approximately 6.5km west of the intersection of U.S. Highway 20 and Highway 13 in Iowa. The collected RAP materials were dried outside at 32℃ for two days.
To develop the field RAP gradation, first, RAP materials were divided into five stockpiles which were retained on the following sieves: 25mm, 19mm, 9.5mm, 4.75mm and passing 4.75mm. After discarding RAP materials bigger than 25mm, the divided RAP materials were weighed and their relative proportions were computed.
이론/모형
To determine the moisture susceptibility, indirect tensile strength of dry and wet conditioned CIR-EE and CIR-foam specimens were measured following ASTM D 6931 (ASTM 2007) . The same conditioning procedure used for the Marshall stability test was adopted for the indirect tensile test with one difference that all tests were conducted at 25℃. The indirect tensile strength and the tensile strength ratio (TSR) of the laboratory specimens can be computed as follows:
성능/효과
Our preliminary investigation seemed to indicate a better performance of CIR-EE mixtures compared with CIR-foam mixtures, particularly in wet conditioned indirect tensile strength and raveling tests. It should be noted, however, that a pug-mill mixer was used to mix the CIR-EE mixtures with RAP materials whereas a bowl mixer was used to mix CIR-foam mixtures with RAP materials.
Although the indirect tensile strengths of dry conditioned CIR-foam specimens were slightly higher than those of dry conditioned CIR-EE specimens, indirect tensile strengths of wet conditioned CIR-EE specimens were significantly higher than those of wet conditioned CIR-foam specimens. Overall, the CIR-EE specimens achieved higher TSR values of approximately 70% than the CIR-foam specimens which exhibited TSR values of about 50%.
Figure 8 shows the average Marshall stability values of dry and wet conditioned CIR-EE and CIR-foam specimens and Marshall stability ratio for two compaction methods. Overall, the Marshall stability values of the CIR-EE specimens were quite similar to those of CIR-foam specimens, with the exception of the Marshall hammer compacted wet specimens, although the CIR-EE specimens were less dense than the CIR-foam specimens. Due to the moisture conditioning, the reduction in Marshall stability of CIR-EE specimens is a slightly less than that of CIR-foam specimens.
However, when the specimens were cured for a longer period of time, say 8 hours, virtually no raveling was observed from either specimen. Therefore, it can be concluded that the raveling test is very sensitive to the curing time of the test specimens, but the behavior after four hours curing would imply that the CIR-EE mixture develops cohesive strength more quickly than the CIR-foam mixture.
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