• International Journal of Highway Engineering
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• v.18 no.3
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• pp.1-9
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• 2016

PURPOSES : This study aims to show the difference of the binder aging level in the hot-mix asphalt (HMA) mixture after short-term aging (SA) under different aging conditions, such as mixture temperature and duration in hour. METHODS : Three SA times (i.e., 1 h, 2 h, and 4 h) at two temperatures (i.e., $160^{\circ}C$ and $180^{\circ}C$) were used for the normal mixtures prepared using a PG64-22 asphalt. The field long-term aging (LA) was simulated by applying the same LA procedure (65 h at $110^{\circ}C$) to all compacted specimens, prepared at the air void of 7% using each SA-treated mixture, in a convection oven. The binder aging level was measured in terms of large molecular size by gel-permeation chromatography (GPC) from the mixture and the absolute viscosity (AV) from the recovered binder. The aging levels were evaluated using those two properties after SA and LA, and then compared based on the normal SA (NSA) mixture (1 h at $160^{\circ}C$). The service life reduction caused by SA in various conditions was estimated based on the aging level of the field cores from different locations in various service lives. RESULTS : The results of the laboratory evaluation indicated that the binder of the mixture, which was treated at longer SA time and higher temperature, showed a significantly higher aging level than the NSA mixture. The binder aging level from a longer time, such as 2 h and 4 h SA, or at a higher temperature ($180^{\circ}C$), were estimated to be similar to that of the mixtures, which had already been in field service for several years. CONCLUSIONS : The HMA mixture should be produced at a moderate temperature, such as $160^{\circ}C$, and placed within a limited hauling and queuing time to avoid a significant short-term aging of the binder before placement in the field pavement. The SA for a longer time at a higher temperature than the NSA condition was found to be detrimental to the service life of the asphalt pavement.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.29-38
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• 2020

Since some warm-mix asphalt (WMA) concretes were known to show poorer rut resistance than the hot-mix asphalt (HMA) concretes, many studies were performed in efforts of improving its performance at high temperature. The reason is assumed to be due to the moisture remaining in aggregates dried at lower temperature. Therefore, not only the rut resistance, the crack resistance of WMA concrete was also in question. In this study, fatigue life of WMA concrete was evaluated in comparison with HMA using 3-point bending (3PB) beam test. The asphalt mixtures were prepared based on Korean mix-design guide using a 13 mm dense-graded aggregate and 6 binders; two HMA binders and four WMA binders. By 3PB fatigue test, normal (unmodified) and polymer-modified WMA concretes were evaluated in comparison with normal and polymer-modified HMA concretes at a low temperature (-5℃). The results showed that most of WMA concretes showed longer fatigue lives than HMA concretes, even though the same PG binders were used for HMA and WMA. This result indicates that the WMA concretes have stronger resistance against fatigue cracking than HMA at the low temperature, and this result is in contrast to the high-temperature performance test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.271-278
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• 2010

Semi rigid pavement is a pavement type using advantages of both flexibility of asphalt pavement and rigidity of concrete pavement by infiltrating cement paste into voids of open graded asphalt mixtures. The semi rigid pavement has better smoothness and smaller driving vibration or noise comparing to the concrete pavement, and has smaller permanent deformation and has temperature falling effect comparing to the asphalt pavement. The temperature falling effect were investigated at a semi rigid overlay pavement test section, and the temperature falling and water retaining effects were verified by measuring the temperature and weight of specimens at a housetop. Horizontal and vertical stresses and strains were compared by structural analysis of the semi rigid pavement and asphalt pavement using the Abaquser o, a commercial 3D finite element analysis program. The results were verified by Bisar 3.0, a multi-layered elastic analysis program. Performance of the semi rigid pavement and asphalt pavement were compared by predicting fatigue cracking based on the structural analysis results.

• International Journal of Highway Engineering
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• v.2 no.4 s.6
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• pp.123-131
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• 2000

The compaction equipment and the Marshall stability head are the two important testing equipment for the Marshall test. The compaction equipment is closely related to the air void, VMA and compactability of the mixtures, and the stability head is related to the Marshall stability and the flow, therefore the size and the shape of the equipment is essential for finding the accurate optimum asphalt content for the asphalt mix design. However, the size and the shape of the equipment currently used and the condition of the installation of compaction pedestal in this country are different from each agency and manufacturer. The national inspection of the Marshall equipment is necessary because the difference can affect the test results and also the performance of the asphalt pavement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4267-4273
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• 2011

In order to select the best compatibilizer for PE/asphalts mixtures, compatibilities of poly(ethylene-co-acrylic acid) and poly(ethylene-co-methacrylic acid) based ionomers with asphalts were investigated via optical microscopy, thermal analysis and rheology. By comparing the polarities of ionomers through an ultimate adsorption of moisture, it was observed that the compatibilities of ionomers increase with the increases of the polarities. By rheological investigations, some of ionomer were observed to be not only compatible but also miscible with asphalts.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.77-87
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• 2006

Dynamic stability (DS) in the wheel tracking (WT) test is used as a basic index of rut-resistance for asphalt mixtures. In general, the deeper rut depth is obtained from the weaker mixture, resulting in the lower DS value. On the other hand, the shallower rut depth is obtained from the stronger mixture, resulting in the higher DS. However, it is not always the case when the DS is calculated by the existing method because the DS is simply determined based on the slope at the final stage of the rut depth-cycle curve. Specifically, in the case of the depth-cycle curve showing a steeper slope in the early part but flatter slope in last part, the DS is calculated to be higher than the curve showing a ever-increasing slope throughout the test. As long as the last part of slope is flatter, the deeper final rut depth is evaluated to show a higher DS than the little final rut depth. Therefore, a reasonable method for DS evaluation need to be established. Several new methods were suggested by considering the early, middle and final parts of rut depth to determine a reasonable DS. The results have shown that those new methods have demonstrated a significant improvement in distinguishing similarly performing mixtures. The result also showed that $DS_2$ had better correlation with SD than any other methods , representing the rutting resistance of asphalt mixture very well. The new DS calculation method is relatively simple and easy to follow. More validatin study is required for practical application.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.91-102
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• 2005

This study dealt with correlation analysis of binder stiffness with deformation strength and dynamic creep property of asphalt mixtures for evaluation of applicability of deformation strength $(S_D)$. Two aggregates, with maximum size of 13mm and eight binders were used to produce 16 different mixtures. The stiffness of binder $(G^*/sin\delta)$ was measured using DSR at $64^{\circ}C$. Final deformation(FD) and dynamic stability(DS) were measured by dynamic creep (DC) test, and SD was measured by Kim test for each mixture. Results of correlation analysis between $G^*/sin\delta$, and $S_D$, m and DS showed that correlation with binder stiffness and deformation strength was the highest $(R^2>0.88)$. There was good correlation between DS, FD with $S_D$. The results indicated that rut-resistance property of mixture is better reflected in $S_D$ test than FD or DS of dynamic creep test. Therefore, it is concluded that $S_D$ can be possibly used for evaluation of rut resistance of asphalt concretes with a good reliability if the procedure is standardized.

• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.1-13
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• 2004

This study dealt with size effect of specimen in measuring deformation strength and estimating rut resistance of asphalt concretes under static loading using Kim test. Two aggregates, a normal asphalt (pen 60-80) and 6 polymer-modified asphalt (PMA) binders were used for preparation of 14 dense-graded mixtures. Mixtures were prepared based on optimum asphalt content by Marshall compactor (S= 10cm) and gyratory compactor (S= 15cm) for Kim test and for wheel tracking test. In statistical analysis by general linear model (GLM) procedure of SAS, the diameter of specimen was found not to be a significant factor that affect the Kim test result. Therefore, it was found that either loom-diameter or 15cm-diameter of specimen gave no significant difference in deformation strength ($K_D$) values in Kim test for any aggregate mixture. However, the thickness of specimen was found to be a significant factor in determining $K_D$. It is estimated that $K_D$ is a function of y, vertical deformation, and y has something to do with thickness of specimen. Therefore, it is suggested that the thickness of specimen should not be higher than 6.6cm, and the correction factor depending on the thickness value should be developed in the future study.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.37-46
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• 2004

This study was performed to establish valid methodology for determining dynamic stability(DS) of deformation-cycle curve which is obtained through wheel tracking(WT) test, the most widely used method for forecast of rutting tendency of asphalt mixture. Existing Korean and Japanese methods for DS are unrealistic and do not really reflect characteristics of rut resistance of asphalt concretes especially when the slope of deformation-cycle curve is stabilized at the end. It was proved that the new DS developed in this study reflected rut resistance characteristics better than existing methods. It is especially effective to distinguish the mixtures with high DR(depth of rut) but stable slope at the end of curve from the mixture with lower DR and continuous slope. The field evaluation must be followed to prove whether the mixture which shows a high DS value this method perform well in the filed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.947-954
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• 2014

In general, Fracture of the material is not occurring of the maximum normal stress or the maximum shear stress failure in the state. Maximum normal stress and maximum shear stress in the state of Critical coupling from being destroyed based on the Mohr-Coulomb theory. Couple of different mixtures, including permeable asphalt pavement, SMA and dense-graded asphalt mixture, were used for compression triaxial test at $45^{\circ}C$ and $60^{\circ}C$. Mohr-Coulomb theory to the analysis of compression triaxial test result of the internal friction angle $38.9^{\circ}{\sim}46.9^{\circ}$ measured somewhat irregularly, but in the case of cohesion, depending on whether the temperature and immersion of the specimen appeared differently. In addition, Indirect tensile test and compression triaxial test of the asphalt mixture to determine the correlation between compression triaxial test results assessed as cohesion and internal friction angle calculated using the theoretical Indirect tensile strength and measured indirectly tensile strength were analyzed. The Measured & Predicted IDT St values tended to be proportional.