• Structural Engineering and Mechanics
• /
• v.59 no.2
• /
• pp.373-385
• /
• 2016

During recent years researchers performed large effort to increase the service life and asphalt stability of the roads against traffic loads and weather conditions. Investigations carried out in various aspects such as changes in gradation, addition of various additives, changes in asphalt textures and etc. The objective of this research is to evaluate the advantages of adding recycled glass powder (RGP), Crumb Rubber (CR), styrene-butadiene rubber (SBR) and styrene butadiene styrene (SBS) to base bitumen with grade of 60/70 for modification of asphalt concrete. Initial studies conducted for determining the physical properties of bitumen and modifiers. A series of asphalt concrete samples made using various combinations of RGP, CR, SBR, SBS and base bitumen. All samples tested using Indirect Tensile Strength (ITS), Indirect Tensile Strength Modulus (ITSM) and Marshall Stability Tests. The new data compared with the results of control samples. The results showed that replacing RGP with known polymers improved ITS and ITSM results considerably. Also the Marshall Stability of modified mixtures using RGP is more than what is found for the base blend. Ultimately, the new RGP modifier had a huge impact on pavement performance and results in high flexibility which can be concluded as high service life for the new modified asphalt concrete.

• Journal of the Korean Mathematical Society
• /
• v.47 no.1
• /
• pp.41-62
• /
• 2010

In this article, we discuss a Grobner basis algorithm related to the stability of algebraic varieties in the sense of Geometric Invariant Theory. We implement the algorithm with Macaulay 2 and use it to prove the stability of certain curves that play an important role in the log minimal model program for the moduli space of curves.

• International Journal of Highway Engineering
• /
• v.19 no.2
• /
• pp.75-85
• /
• 2017

PURPOSES : The purpose of this study was to determine the optimum mix design of the content of 100 % reclaimed asphalt pavement (RAP) for spray injection application with different binder types. METHODS : Literature review revealed that spray injection method is the one of the efficient and economical methods for repairing a small defective area on an asphalt pavement. The Rapid-Setting Polymer modified asphalt mixtures using two types of rapid setting polymers-asphalt emulsion and a quick setting polymer asphalt emulsion-were subjected to the following tests to determine optimum mix designs and for performance comparison: 1) Marshall stability test, 2) Retained stability test, 3) Wet track abrasion test, and 4) Dynamic stability test. RESULTS and CONCLUSIONS : Type A, B, and C emulsions were tested with different mix designs using RAP aggregates, to compare the performances and determine the optimum mix design. Performance of mixtures with Type A emulsion exceeded that of mixtures with Type B and C emulsion in all aspects. In particular, Type A binder demonstrated the highest performance for WTAT at low temperature. It demonstrated the practicality of using Type A mixture during the cold season. Furthers studies are to be performed to verify the optimum mix design for machine application. Differences in optimum mix designs for machine application and lab application will be corrected through field tests.

• Elastomers and Composites
• /
• v.43 no.2
• /
• pp.72-81
• /
• 2008

Nowadays, modifying asphalt to improve the resistancy of plastic deformation or rutting on roads has been drawing attention. In this study, asphalts were modified with modifying agents and ground rubber from waste tire (GRT), and the effects of modifier and GRT on the properties of asphalt were analyzed. The Marshall stability of modified asphalt was increased by 98% and the tensile strength increased by 43% compared to straight asphalt. GRT played an important role in enhancing these properties. Viscosity tests, penetration tests and TMA analysis showed the deformation resistancy of modified asphalt. IR and GPC tests indicated that asphalt and modifier have similar chemical structures to each other, and chemical bonding between asphalt and modifier have occurred so that the molecular size lengthened.

• International Journal of Highway Engineering
• /
• v.18 no.3
• /
• pp.67-74
• /
• 2016

PURPOSES : This study evaluated the field applicability and laboratory performance of glass fiber-reinforced asphalt (GFRA) mixtures. METHODS : The general hot-mix asphalt (HMA) and GFRA mixtures were paved in five sites, including three national highways, one express highway, and an arterial road, to evaluate field applicability and durability. The plant mixing and construction method for the GFRA were similar to those for the general HMA. The lab performances of the field samples were relatively compared through the mechanical measures from the Marshall stability, indirect tensile strength, and dynamic stability. The field performance was surveyed after a year. RESULTS : The lab tests verified the superior lab performances of the GFRA compared to the general HMA. The Marshall stability of the GFRA increased for about 128% of the general HMA. The indirect tensile strength of the GFRA was 115% greater than that of the general HMA. The dynamic stability of the GFRA resulted in 16,180 reps/mm, which indicated that high rut resistance may be expected. No noticeable defects, such as cracks or deformation, were observed for the GFRA sections after a year. CONCLUSIONS : The lab tests and field survey for the five GFRA sites resulted in superior performances compared to the general HMA. The relatively low-cost GFRA, which required no pre-processing procedures, such as polymer modification, may be a promising alternative to the polymer-modified asphalt mixtures. The long-term performance will be verified by the superior field durability of the GFRA in the near future.

• International Journal of Highway Engineering
• /
• v.8 no.1 s.27
• /
• pp.15-23
• /
• 2006

Criteria of the current asphalt mix design, Marshall method, includes the stability and flow which are not related with field performance of HMA mixture, together with the air void, Void filled with asphalt (VFA) and/or Void of mineral Aggregate(VMA). In addition, the limits of stability and flow are satisfied in most cases, the Optimum asphalt content (OAC) is determined based on volumetric properties, such as the air void and/or VFA and/of VMA. Therefore, many researchers have sought mechanistic properties which can replace the stability and flow, making the designed mixture having potential for better field performance. This study initiated to develope a mix design by introducing two performance-related mechanistic properties, the deformation strengh and fracture energy, in place of the stability and flow of the Marshall method. The deformation strength $(S_D)$ from the Kim Test has a high correlation with rutting property and the fracture energy(FE) from the indirect tensile test represents the fatigue cracking property of asphalt mixture. Four types of asphalt mixture were prepared for examining possibility of using the suggested mix design method in comparison with current methods. The results showed that mechanical properties were reflected in determination of OAC with this suggested mix design, unlike the existing Marshall method.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.3
• /
• pp.305-312
• /
• 2017

This paper presents a laboratory investigation into the effects of fillers using industrial by-product such as coal ash, IGCC slag on properties of hot-mixed asphalt concrete variation with filler content. For comparison, existing mixture with lime and dust have also been considered. Marshall and flow test has been considered for the purpose of mix design as well as evaluation of mixture. Other performance tests such as indirect tensile strength test, tensile strength ratio(moisture susceptibility), dynamic stability have also been carried out variation with filler content. It is observed that the mixes with industrial by-product exhibit conform with quality standard. Therefore, it has been recommended to utilize industrial by-product based on fly ash wherever available, not only reducing the produce cost but also partly solve the industrial by-product utilization and disposal problem.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3888-3893
• /
• 2014

The number of waste tires is increasing. One effective recycling method is the pyrolysis of waste tires. Using the pyrolyzed carbon black from waste tires, the characteristics of permanent deformation for PA-13mm porous mixture were evaluated. The confining pressure of 138 kPa and deviatoric stress of 551 kPa were adopted. The testing temperature was $45^{\circ}$ and 50 gyrations of the gyratory compactor was used to simulate the medium traffic level. The mixture modified by 10% PCB showed the largest Marshall Stability of 3.41 kN. The stability of the mixtures with PCB was 50% higher than that of mixture without PCB. The limited laboratory test showed that the use of PCB in a porous pavement decreases the permanent deformation and will be an effective alternative method to reducing the permanent deformation of a porous pavement.

• Safety and Health at Work
• /
• v.4 no.1
• /
• pp.46-51
• /
• 2013

Objectives: Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. Methods: Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. Results: Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. Conclusion: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.113-116
• /
• 2007

This is a research for evaluated recycled glass powder to add asphalt concrete filler. To make a comparative study, Mechanical performance of lime stone and slag dust Mixtures was evaluated according to test procedure. Lab. performance tests included marshall stability, indirect tensile strength, resilient modulus and wheel tracking. Water resistance tests were evaluated by marshall strength ratio and tensile strength ratio. In conclusion, Results of mechanical performance showed that recycled glass powder mixtures were equivalent to conventional mixtures. Especially, result of tensile strength ratio tested recycled glass powder mixtures was superior to conventional mixtures.