아스팔트 혼합물의 용적 및 강도 특성에 근거한 적정 다짐온도의 결정 연구

다국어 초록 (Multilingual Abstract)

In order to determine the optimum compaction temperature range based on volumetric and strength properties of asphalt mixtures, this experimental study was conducted using Marshall compactor and Superpave gyratory compactor. Two dense-graded aggregates with maximum size of 13mm and 19mm for surface course asphalt mixtures, which is most widely in use in Korea, were used in this study. Two hot mix asphalt (HMA) mixtures and a warm mix asphalt (WMA) mixture were prepared. The binder for HMA mixtures were a PG64-22 normal asphalt and a PG76-22 polymer modified asphalt (PMA), and the binder for a WMA mixture was a PG70-22 asphalt. The bulk density (Gmb), air-void ratio, voids in mineral aggregates (VMA), void filled with asphalt (VFA), and deformation strength as strength property were used as variables for analyses of the effect of compaction temperature. The compaction temperatures used for evaluation of WMA were 75, 95, 115 and 135oC, those of HMA were 115, 135, 155, and 175oC. The conclusions drawn from this experimental study are as follows:

1. The method of determining compaction temperature using viscosity, which was originally used for determination of compaction temperature, was found to be only appropriate for normal (non-modified) asphalt binder. When it was applied to polymer-modified asphalt (PMA) and WMA binder, the temperature determined thereby were too high to use practically. Because of too high temperature level, if the temperature is used, the asphalt may be damaged, which is a similar result to the previous foreign study.

2. When determining compaction temperature using volumetric and strength properties, the compaction temperatures of HMA with Marshall compactor and Superpave gyratory compactor showed, in general, no meaningful difference between two compactors, even though there were somewhat minor differences depending on the binder grade. From the study results, the suggested compaction temperatures which were adjusted for practically usage for HMA are 130～155℃ for PG64-22 and 135～160℃ for PG76-22. Those are as much as 40℃ lower than what was obtained by the viscosity method.

3. The WMA mixture was less influenced by compactor and aggregate grain size because its compaction was possible even at 95℃, but the optimal temperature was found to be 115∼140℃. By virtue of the WMA additive used for reducing viscosity of binder and workable temperature, it showed almost the same compaction work as for HMA at those lower temperature ranges.

4. In case of 13㎜ HMA, the gyratory compaction was possible at a temperature approximately 20℃ lower than the Marshall compaction. This mean the former provided more efficient compaction. On the other hand, in the case of 19㎜ HMA, the temperature was found to be almost the same for the two compactors, showing that there is some influence of compaction temperature due to aggregate size.

5. Analyses of compaction properties of gyratory compactor and marshall compactor found out that 21 out of 24 mixtures showed Air-void differences within 1%. This shows that the gyratory compaction level has the same compaction amount as the Marshall level. Therefore, the gyratory compaction level in the 2009 Guide by Ministry of Land, Transportation and Maritime Affairs was proved to be a reasonable value.

6. Analyses of compaction temperature based on the deformation strength (SD) by Kim Test indicated that the gyratory compactor had similar compaction work at the temperature almost 20℃ lower than the Marshall compactor. Also, in case of Marshall compaction of WMA mixture, some SD values was fallen below standard limit at some temperatures, but the gyratory compactor showed similar results as those of HMA, demonstrating gyratory compactor more efficiency for WMA.

7. Based on above study results, a method for preliminary determination of an optimum compaction temperature was suggested using an estimated asphalt content and the compaction temperature for binder and compactor given in Table 4-15. After preliminary determining an optimum temperature, it can be used for mix design of the same mixture. Following the determination of OAC, the determined temperature can be provided to the plant to control the manufacturing temperature so that the issue of discrepancy of mix-design results between the lab and the plant may be resolved.

From the above results, the method developed in this study for determining an optimum compaction temperature may be applied to newly developed asphalt binders or existing asphalt binders and mixtures as the most effective way for compaction temperature determination.

목차 (Table of Contents)

• I. 서 론 1
• 1. 연구배경 1
• 2. 연구목적 3
• II. 연구사 4
• 1. 다짐온도 관련 연구 4
• 2. 변형강도 관련 연구 9
• III. 재료 및 방법 15
• 1. 사용 재료 15
• 1.1. 바인더 15
• 1.2. 골재 17
• 1.3. 준고온화 첨가제(Warm-mix additive) 19
• 2. 시험 방법 21
• 2.1. 배합설계 21
• 2.2. 회전점도(Rotational viscosity) 24
• 2.3. 용적특성관련 시험 26
• 2.4. 변형강도 시험 26
• IV. 결과 및 고찰 30
• 1. 회전점도(Rotational viscosity) 시험 결과 31
• 2. 마샬 다짐기를 사용한 배합설계 결과 34
• 3. 선회 다짐기를 사용한 배합설계 결과 61
• 4. 다짐온도별 다짐 특성 분석 85
• 5. 다짐기별 다짐 특성 분석 92
• 6. 다짐온도에 따른 변형강도 특성분석 96
• 6.1. 마샬 다짐기 96
• 6.2. 선회 다짐기 102
• 7. 다짐온도 결정방법 107
• V. 결 론 110