In 1924, natural roack asphalt, which is called Asbuton, was found in South East Sulawesi, Buton Island, Indonesia. Since 2006, Asbuton has been widely applied on national road, provincial road and district roads not only for low volume traffic roads but also for the medium and heavy traffic roads. The use of Asbuton in Indonesian road infrastructure development is increasing because the deposits are estimated to be 677 million tons while current annual production is only approximately 20,000 tons. Asbuton mainly consist of asphalt and mineral like a Trinidad Lake Asphalt. The asphalt content of Asbuton is about 35% or less. Many researchers agreed that pure asphalt binder should be separated from its minerals of Asbuton in order for the conventional asphalt binder to be used widely and economically. Asbuton could replace the conventional asphalt binder. In this study, fundamental and reheological properties of pure asphalt binder extrcted from Asbuton are evauluated to find a possiblity to repalce it as the conventional asphalt binder. The first, pure asphalt binder extrcted from Asbuton through extraction process. Second, penetration test, softening point test, ductility test, and flash point test are conducted to measure physical properties of pure asphalt binder extrcted from Asbuton. Third, dynami shear rheometer (DSR) test, rolling thin film ovens(RTFO) test, pressure aging vessel(PAV) test, and bending beam rheometer(BBR) test are conducted to determine perfoemance grade as a reheological properties. Based on the limited laboratory test results, pure asphalt binder extrcted from would be possibly used as modified additive to improve physical properties and the performance grade at high tempertaure.

Recently, there is an increasing the pavement distresses such as rutting with an increase in heavy vehicles on the road in Mongolia. Rutting is the longitudinal depression in the wheel path in asphalt pavements and it causes a hydroplaning and severe safety concern for users. This study aims to develop paving material that can prevent rutting on the road pavement by improving the durability of the asphalt mixture in Mongolia. Therefore, this study was carried out using the technique of reinforcing the material by adding fibers to conventional asphalt mixture. Fibers have been used to reinforce various materials for many decades in various parts of the world. It is generally understood that asphalt is strong in compression and weak in tension. Adding fibers with high tensile strength can help increase the strength of a mixture[1]. A mixture of glass fibers was used in this study to evaluate the performance characteristics. In coordination with the City of Ulaanbaatar, The test section selected in this study was Peace Avenue in Ulaanbaatar. The test section was a bus lane with severe rutting by heavy vehicles. The designated road test section performed cutting and overlay using five asphalt mixtures: Glass Fiber-reinforced Asphalt, Hot Mix Asphalt(10mm, 19mm), Polymer Modify Asphalt(2 types). The performance survey was conducted after the summer. As a result, No noticeable cracks were observed in glass-reinforced mixture section and the rut-depth of the glass-reinforced mixture is lower than other mixtures[2].

Development of high-performance eco-friendly cold asphalt and its manufacturing system

Generally, remarkable amount of Reclaimed Asphalt Pavement (RAP) is produced annually by pavement surface cutting: due to early distress on asphalt pavement layer and remodelling construction work on existing aged-asphalt pavement layer. In South Korea, various types of research on proper and optimized RAP material development and field application (including evaluation process) are performed because of increase of existing road maintenance budget and technology. The major material of RAP is recycled aggregate coated with aged asphalt binder. The advantages of application of RAP on asphalt pavement are recyclable material proportion can be increased due to re-using of existing aggregate and eco-friendly characteristics. However, more amount of specific additives (and/or agent) needs to be implemented during production with increase amount (and/or proportion) of RAP on virgin asphalt material inevitably. This action is highly needed because of recovery of penetration grade and absolute viscosity of final production. The required amount of additives tends to be vary based on different aging level of RAP, amount of RAP and types of virgin asphalt binder. But it is well known that required amount of additives tends to be increased with increase of RAP proportion compared to virgin asphalt mixture. Moreover, it also should be known that mere increase of additives on RAP asphalt can provide negative effect on its quality and mechanical performance. In this study, high penetration grade asphalt binder: contains between 200 and 300 level of penetration grade, was used for producing RAP asphalt mixture with small amount of required additive application. After the sample preparation, various characteristics of RAP asphalt were analysed with extensive experimental work.

Recently, Cambodia has been investing a lot of money in the construction and maintenance of roads, which are social infrastructures. However, damage to the existing pavement is accelerating due to the old age of the road pavement, poor drainage facilities and increase in heavy traffic. To solve this problem, a fundamental solution such as a high-performance asphalt mixture is required to extend the life of road pavement. In this study, a high performance glass fiber reinforced asphalt mixture developed in Korea was applied to Cambodia. Prior to field application, Marshall stability tests were performed on glass fiber reinforced asphalt mixtures, SBS modified asphalt mixtures and asphalt mixtures commonly used in Cambodia. The Marshall stability test showed that the glass fiber reinforced asphalt mixture and the SBS modified asphalt mixture had the same strength (about 1.3 times higher strength than the usual asphalt mixture). In addition, the test construction was carried out on the National Highway 2 of Cambodia for the evaluation of the performance of the three mixtures. In the future, the long-term performance evaluation of each mixture will be conducted through follow-up survey of the test construction area.

One major concern of Seoul City is the premature failure occurrence such as fatigue cracking and rutting in the pavement. Due to the acceleration at intersections and low vehicle speed at bus stops that cause higher shear and critical strain on the pavement. Because of this, there is a need to develop a new mixture that can withstand bus stop and intersection traffic while preventing premature failure. In this study, a high modulus asphalt mixture was adapted and developed to address the cracking and rutting concerns at bus stops and intersections of Seoul City. Indirect tensile (IDT) and beam fatigue testing were conducted to determine the fatigue performance of the high modulus asphalt mixture (HMB). In addition, the behaviour of the HMB considering loading speed and temperature were investigated using the IDT dynamic modulus test. It was found that the HMB performs 3 and 1.5 times better compared to conventional asphalt using IDT and beam fatigue test respectively. Moreover, it was observed that modulus value of HMB is two times better at low frequency (high temperature) compared to conventional asphalt. The dynamic modulus value of the HMB was then used as input for bus stop and intersection scenario analyses. It was found that HMB can reduce the total thickness of the pavement around 4 to 6cm compared to the conventional asphalt. It can be concluded that because of the better fatigue and rutting performance and high modulus value of HMB at low frequency, it can perform better in bus stops and intersections. It is recommended to conduct field construction to further evaluate the performance of HMB asphalt mixtures in the field.

In this study, we conducted laboratory tests to evaluate the moisture resistance of the asphalt mixture containing air-cooled slag. Generally, in Korea, hydrated lime is used up to 1.5% of the aggregate weight to improve the moisture resistance of the asphalt mixture. The slag used in this study is a byproduct produced in the steel industry and can be produced through a specific process. And its chemical composition is similar to that of the hydrated lime stone and satisfies the filler quality standards of the Ministry of Land, Transport and Transport. In order to evaluate the moisture resistance of the asphalt mixture containing air-cooled slag, we conducted the dynamic immersion test, which is a non-compaction mixture test. Also we conducted the indirect tensile strength ratio test and the Hamburg wheel tracking test for compaction asphalt mixture test. As a result of the dynamic immersion test, the effect of stripping prevention was similar to that of hydrated lime because it did not show much difference from the hydrated lime mixture. In the case of indirect tensile strength test, the specimens prepared in the laboratory and on the site satisfied the quality standards of the Ministry of Land, Transport and Logistics and the TSR value increased with increasing the content of air-cooled slag. However, when the content of air-cooled slag is more than 2%, the indirect tensile strength value is getting lower. So it is judged that the appropriate content should be determined to be 2% or less. In the case of the Hamburg wheel tracking test, when the steel wheel load passed 20,000 times on the asphalt mixture containing 2% of air-cooled slag, it showed 5.27mm deformation. And the stripping point was not observed. In this study, it was found that when the air-cooled slag is used as a substitute for hydrated lime, the moisture resistance of the asphalt mixture can be improved. It is considered that the aircooled slag can be used for the asphalt pavement material through the characteristics analysis of mechanical and field application in the future

In this paper, first the aging level of Stone Mastic Asphalt (SMA): one of the widely applied asphalt mixture types for highway construction in South Korea, was analysed then those aging effects on various performance characteristics were studied. Then, a suitable methodology for improving performance on real asphalt pavement construction site was recommended. To fulfil the objective, Gel-Permeation Chromatography (GPC) experimental work was performed on various aged SMA mixtures by measuring Large Molecular Size (LMS) then the Absolute Viscosity (AV) value was predicted based on the findings in the previous step. As results, it was found that types of performance change on aged asphalt binders could be estimated by computed Estimated Absolute Viscosity (EAV) values. It also should be mentioned that the performances of tested SMA mixture presented negative trend after aging effect increases; even though the performance deterioration level of SMA is lower than that of regular Dense Grade Asphalt (DGA) mixture, which means proper reactions are recommended to keep its quality. Moreover, better resistance against aging effect was found by applying Hydrated-Lime (HL) or Low Density Poly-Ethylene (LDPE) compared to any other additives on asphalt mixtures. A unique Aging Quantity (AQ) model for SMA mixtures was developed by using two factors: collected aging time data set from field (and/or laboratory) and AV values based on different temperature conditions. The Predicted Absolute Viscosity (PAV) on SMA mixtures was computed by using the introduced AQ model then the aging level of asphalt binder was estimated as a final step. Additionally, five performance characteristics of asphalt binder: Dynamic Shear Rheometer(DSR) high temperature limit, Bending Beam Rheometer (BBR) low temperature limit, G*/sinδ, Creep stiffness, and m-value, were analysed. The value of AV showed the best performance for predicting and representing aging level. Finally, the aging level of given asphalt mixtures in the field can be easily predicted by choosing one of three approaches presented in this research. It can be concluded that the performance of asphalt pavement can be increased by selecting proper materials and performance prediction methodologies introduced in this study. However, only limited number of specimens were considered in this study due to limit of raw materials and laboratory equipment condition. Therefore, extensive experimental works with various types of asphalt materials are recommended for strengthen findings in this thesis as a future research.

This study shows the development of a photocatalytic technology for the road to decompose the nitrogen oxides(NOx) using a titanium oxide(TiO2) photocatalyst coating method for reducing the air pollution

The Semi-Rigid Pavement (SRP) mixture is composed of Gap Graded Asphalt (GGA) mixture (air void = 20~28%) and cement paste. By inserting cement paste into voids in GGA mixture, SRP can provide not only flexibility but also rigidity characteristics on pavement performance. SRP can mitigate pavement surface temperature increase during summer session, provide better smoothness and mitigate rutting distress due to heavy weight vehicles, successfully. In Japan, SRP is widely applied in cross section area, heavy vehicle parking lot and highway ticketing booth in highway network system. In South Korea, SRP was introduced and applied since 2005. However, still more researches and studies are needed to understand material characteristics and improve performance of SRP. Moreover, the current SRP system in South Korea merely follows and adapts the aggregate gradation information from Japan which needs to be amended and customized into original material (i.e. aggregate, binder and cement) situation of South Korea. In this paper, SRP system based on Stone Mastic Asphalt (SMA) mixture design originated from Korea Expressway Corporation (KEC) and enhanced cement paste with addition of fly-ash and slags was developed. In addition, an optimized proportion between asphalt mixture air voids and cement paste amount with consideration of economic benefit was introduced. Based on field evaluation process it can be said that the newly developed SRP system can successfully adapted not only in static site on highway: parking lots or ticketing booth, but also in dynamic site on highway: driving and wheel path.

Since the first development of asphalt emulsion in 1920, the asphalt emulsions have been in existence for almost 100 years. The advantages of asphalt emulsion compared to hot asphalt and cut back binders are related to the low application temperature, compatibility with other water-based binders like rubber latex and cement, and lowsolvent content. Surface active agents(surfactants), also known as emulsifiers or emulsifying agents, are needed to provide the stability required over time. The type of asphalt emulsion is largely divided into two for the mixture which acts as a binder by mixing with the aggregate and for the bonding strength between asphalt pavement layers. The cold recycled asphalt mixture is affected the binding strength between asphalt and aggregate, depending on the properties of the asphalt binder as well as the emulsifier properties. Four kinds of emulsifiers(alkyl amines, ligine amine, fatty amine, alkyl amido polyamines) were used to make emulsified asphalt, and their basic properties (storage stability, cement mixing test, penetration, etc.) and aggregate film separation were measured. As a result, the penetration of the asphalt emulsion made by the type of alkyl amido polyamines emulsifier was measured to be about 10.4% higher, and the stripping of the bitumen-aggregate film was also lower about 21%. This is because polyamine has two or more primary amino groups –NH2 forms a strong binding force.

Asphalt pavement is covered over 90% of Korea road network. There are various causes for damage to asphalt pavement such as crack, stripping, and joints et al. A longitudinal joint occurs in an asphalt pavement when a new batch of hot-mix asphalt (HMA) is laid adjacent to an existing lane for maintenance of asphalt road. It is required to pave the width of a road in multiple lanes because paving the full width of the pavement in a single pass is usually impossible. The durability of longitudinal joints in asphalt pavements is strongly related with the pavement service life. This longitudinal joint is generated attachment sites where the old pavement surface and the new pavement surface are adhered to each other. In the short period of time, early cracks are generated due to the adherence failure of the new and old pavement. Rainwater penetrates into cracks at the time of rainfall. The cracks are enlarged to be connected by labeling and pothole generation, resulting in durability of the pavement deterioration of its service life. Therefore, there is a desperate need for a preventive material that can prevent the expansion of cracks in the longitudinal joint. Compare performance sealing tape with tack coating material, the research team is adopted freeze-thaw and wheel tracking loading test methods. The sealing tape shows the better performance than tack coating material under traffic loading and freeze-thawing test.

The ride quality (i.e. smoothness) is a key factor for evaluating the construction quality of expressway asphalt pavement. Conventionally, three paving devices are widely used to control the surface layer thickness: leveling sensor (i.e. LS), short-range-surfacing-contact-ski (i.e. SSCS) and long-range-surfacing-contact-ski (i.e. LSCS). However, each of these levelling tools presents one major drawback. In the case of LS, if the original sub-layer evenness is poor, the final asphalt pavement surface and its smoothness will be negatively affected. The SSCS cannot assure satisfactory smoothness when relatively long paving section (in the order of 10 km) are paved. While the LSCS would reduce the drawback of the SSCS, its weight on the one hand and its length on the other discourage its use in the paving site especially for curved sections. In this paper, a next generation pavement smoothness leveling equipment, known as non-contact-digital-ski (i.e. NCDS) was implemented, evaluated and compared to the conventional equipment leveling device. The international Roughness Index (IRI m/km) was measured on sections paved with and without NCDS and the results visually and statistically compared. In addition, for the same sections, the modulus of the pavement layers was computed and compared by means of Falling Weight Deflectometer (i.e. FWD). It was observed that when NCDS is used for asphalt pavement overlay of existing concrete pavement, significant improvement in IRI (i.e. IRI<1.0m/km) and consistently uniform elastic modulus could be achieved compared to the conventional levelling and paving method.

Generally, asphalt binder experiences short-term aging during mixing and constructing processes in high temperature environments and long-term aging during the service life after opening the road. Binder aging inside asphalt mixtures incurs changes in strength of asphalt paved roads, which then changes physical properties of the mixture such as cracks and rutting resistance. This study aims to measure bond strength of aging asphalt binder using asphalt bond strength (ABS) test that can measure a bonding force of asphalt binder and aggregate surface using Pneumatic Adhesion Tensile Testing Instrument (PATTI) used previously in the paint industry as a testing method specified in AASHTO TP-91.

In Korea, concrete pavements were first applied to highways in 1981 and as a result of continued increase in length over the past years, 2,592 km of concrete pavement network is currently in service, of which 1,399 km(54%) of concrete pavements is 10 years or older, and 233km(9%) is 20 years or older. The length of concrete pavement sections nationwide has been steadily on the rise every year (EXTRI, 2017). Approximately 54% of current concrete pavement highway network will reach the service life limit in 2025 which means around 660 billion won is needed for future pavement repair project (EXTRI, 2017). Given that concrete pavements beyond design life still have a remaining service life, it is economically advantageous to repair them before reconstruction. Asphalt overlays are a major repair method for older concrete pavements. Depending on the concrete pavement condition, thickness and mixture of asphalt overlays are determined. Service life of asphalt overlays varies by the presence, time and size of cracks in existing concrete pavements and reflecting crack at joints. Temperature change of concrete pavement is among the major reaction parameters of reflecting crack. Reflecting crack develops when asphalt bottom-up cracking by longitudinal shrinkage and expansion due to temperature change of the concrete base layer, top-down cracking by temperature difference between top and bottom of concrete, and shear stress by traffic loading are combined (Baek, 2010). Crack and joint behaviors of concrete pavement vary between the base layer and the concrete surface of composite pavement system, and different conductivity by mixture and thickness of asphalt overlay leads to temperature change of concrete base course. This study measured temperatures of each layer of diverse composite pavements in place on site and analyzed differences in temperature change of concrete base layer depending on mixture and thickness of asphalt overlays. Overlay thickness parameters were 5cm and 10cm, two values most widely used, while mixture parameters were SMA and porous asphalt. Based on temperature change of concrete surface, this study also evaluated the difference of temperature change in concrete base layer with an asphalt overlay on top. Findings from this study are expected to be utilized for studies on mechanism and modeling of reflecting crack in old concrete pavements with asphalt overlays.

Road construction and maintenance of deteriorated pavement has been continued since industrialization. Demand for aggregate with a good quality has been increasing from limited resources, but it is difficult to supply aggregates smoothly due to environmental protection regulations (Jo et al., 2015). Accordingly, efforts are being made in the road construction industry to utilize industrial products for the purpose of efficient use of resources and environmental preservation. Steel slag which contains a non-reactive CaO is used primarily as a material for embankment and soil covering depending on the expansion and environmental issues. On the other hand, steel slag shows a variety of performance improvements as including increased elasticity factors, increased indirect tensile strength, and improved plastic deformation resistance when handling the expansion issue with sufficient aging processing (Ali et al., 1991, Asi et al., 2007). In this study, the behavior characteristics of the slag asphalt concrete mixture were analyzed according to temperature to encourage the use of steel slag aggregate. Specimens with steel slag showed a higher initial strain than those with natural aggregates. But strain of specimens were nearly similar over the repeated temperature changes. The experimental results for specimens with these characteristics were less likely to cause the performance problems from temperature because the measured strains were relatively small than strain caused from other loads. In conclusion, it is necessary to design and construction process reflecting the behavior characteristics according to temperature to encourage the use of steel slag aggregate.

Recently, road cave-in and depression in urban area due to subsurface cavity are emerging as a social issue in Korea. These phenomena enable to cause not only damage to human lives and properties, but also an anxiety of the citizens. Furthermore, it is a problem that needs more fundamental solution to countermeasure. The objective of this study is to evaluate the stiffness characteristics of asphalt pavement with existence of subsurface cavity using Falling Weight Deflectometer (FWD) deflection and backcalculation analysis using GAPAVE program developed the KICT. The characteristics of FWD deflections are analysed for cavity and intact asphalt pavements. The stiffness reduction in the asphalt pavement due to subsurface cavity was evaluated as a result of this FWD test. The Seoul Metropolitan Government has conducted a Ground Penetrating Radar (GPR) test, coring, and image photographing in four different locations to determine the presence of the cavity and figure out the cavity depth and size underneath asphalt pavements. The cavity depths measured in this section range between 17cm to 51cm, and its lengths are at least 70cm to up to 310cm. It is found from this analysis that the deflections measured from cavity section are generally higher than intact section in same locations. As results of backcalculation analysis, it appears that the backcalculated moduli are generally decreasing with increase of cavity depth. After comparing with AC moduli obtained from intact and cavity section, it is observed that about 80% of moduli was reduced with existence of subsurface.

Modified asphalt pavements are needed to resolve pavement distress problems like rutting, pot-hole and warm asphalt pavements are needed to solve energy saving, reduction of noxious gasses emission and early traffic opening. To present these two characteristics, we developed polymer-modified warm-mix asphalt binder and mixtures and evaluated their performance by optimizing polymer-modified warm-mix additive. As results, physical properties and rheological characteristics of polymer-modified warm-mix asphalt binder are similar to normal modified binder. And we confirmed that polymer-modified warm-mix asphalt mixtures satisfied quality standard of Ministry of Land, Infrastructure and Transport.

In recent years, there have been applied methods for minimizing noise by adjusting the method of installing soundproof walls, soundproof tunnels, soundproofing rims, environmental facilities, etc., and the shape of the surface texture of tire treads and packaging materials for the purpose of reducing road noise. Low noise pavement methods such as rubber asphalt (CRM), open graded asphalt concrete (OGAC), permeable Friction Courses (PFC), open graded friction courses (OGFC) and porous asphalt have been applied to reduce road noise. Especially, porous pavement is the most widely used low noise pavement with porous structure, which can reduce noise and drain water through continuous void of pavement. On the other hand, porous asphalt pavement has problems such as reduction of noise reduction effect and difficulty of road surface management due to void closing and increase of construction cost. The purpose of this study is to develop ultra-thin layer hot mix asphalt pavement method which maximizes road noise reduction effect by surface micro voids (Recover asphalt pavement) to improve void clogging of present porous pavement method. For this study, maximum size 5mm aggregate and cationic-treated fiber reinforced asphalt modifier (CSM) were used. The Marshall design method was applied grain-size distribution curve was based on SMA mix design. Marshall test, TSR, MMLS3 test and Hamburg test were carried out to evaluate the mechanical properties of ultra -thin layered asphalt pavement method with surface micro voids. Also, the effect of road noise reduction was evaluated through field application in urban area.

In this study, several approaches in evaluating moisture sensitivity of asphalt mixtures were investigated and compared. To evaluate the moisture damage resistance, twenty types of asphalt mixtures with and without anti stripping additives were tested in the laboratory. Uniaxial compressive strength (UCS) and indirect tensile (IDT) testing were performed to determine the Tensile Strength Ratio (TSR) and Cohesion Strength Ratio (CSR). Stone Mastic Asphalt (SMA) mixtures were found to provide good moisture damage resistance compared to other mixtures. It also does not require anti stripping additives to improve its moisture resistance. Moreover, the correlation coefficient between the TSR test and CSR tests is 0.99 with an average error of 1.5%, which indicates that the TSR test following AASHTO T-283 is still the most reasonable criteria in evaluating the moisture damage of AC mixtures. Marshall Stability Ratio (MSR) and Marshall Stability to Flow Ratio (MSFR) were conducted and were compared to TSR test results. It was found that MSFR value may be used to evaluate the moisture damage resistance of AC mixtures instead of TSR test. Finally, Dynamic Immersion (DI) test was performed to evaluate moisture resistance for loose asphalt mixtures. The DI results showed good correlation also when evaluating moisture resistance compared to TSR. When using DI testing in evaluating moisture resistance, it is recommended to test after 48 hours since it showed higher correlation with the TSR values. Further study is recommended to improve current testing evaluating moisture susceptibility of asphalt mixtures to properly associate it with TSR values.