PURPOSES : The purpose of this study was to evaluate the common performance of asphalt pavements, determine the timing of preventive maintenance, and determine the optimal timing of application of the preventive maintenance methods by analyzing PMS data. METHODS : Using PMS data on asphalt pavement performance on highways, we derived the major damage factors and evaluated them according to the public period and traffic level. Among the factors evaluated, we determined those that could be improved by preventive maintenance, calculated the amount of change annually, and derived the timing of the application of the preventive maintenance method through correlation analysis. RESULTS : Among highway PMS data factors, crack variation was found to affect preventive maintenance, which increased rapidly after five years of performance. Traffic analysis showed that changes increased rapidly in the fifth, sixth, and seventh years when AADT exceeded 20,000, exceeded 10,000, and was under 10,000, respectively. Analysis of the amount of crack variation according to the pavement type showed that crack variation increased rapidly in the overlay section compared to the general AP section. CONCLUSIONS : Crack variation is the performance factor that was expected to be effective in preventive maintenance, and the PMS data showed that the initial application time of the preventive maintenance method varied by one year, depending on the traffic volume.

PURPOSES : In this study, a method to use magnesium phosphate ceramic (MPC) concrete for the surface maintenance of airport pavements with jointed concrete is developed. METHODS : To investigate the application of a material incorporated with MPC for the surface maintenance of airport pavements with jointed concrete, structures with various cross-sections and thicknesses were constructed. The cross-section of the structure was modeled for the surface maintenance of four types of pavements and typical pavement construction processes, such as cutting, cleaning, production and casting, finishing, hardening, and joint reinstallation. Subsequently, the hours required for each process was determined. RESULTS : The MPC concrete used for the surface maintenance of airport pavements with jointed concrete demonstrate excellent performance. The MPC concrete indicates a compressive strength exceeding 25 MPa for 2 h, and its hydration heat is 52.9 ℃~61.2 ℃. Meanwhile, the crushing and cleaning performed during the production and casting of the MPC require a significant amount of time. Specifically, for a partial repair process, a total of 6 h is sufficient under traffic control, although this duration is inadequate for a complete repair process. CONCLUSIONS : MPC concrete is advantageous for the surface maintenance of airport pavements with jointed concrete. In fact, MPC concrete can be sufficiently constructed using existing concrete maintenance equipment, and partial repair works spanning a cross-sectional area of 11 m2 can be completed in 1 d. In addition, if the crushing and cleaning are performed separately from production and construction, then repair work using MPC concrete can be performed at a larger scale.

PURPOSES : The purpose of this study is to evaluate the performance of an ultra-thin asphalt pavement as a preventive maintenance approach through laboratory tests. METHODS : An ultra-thin asphalt pavement of 2 cm wearing course thickness comprising modified asphalt and aggregate is a preventive maintenance method used for asphalt pavements. A mix design was carried out to determine the optimum aggregate gradation and asphalt contents. A dynamic immersion test was performed to evaluate the water-resistance of the ultra-thin asphalt pavement. A wet track abrasion test and a cohesion test were conducted to examine the applicability of the ultra-thin asphalt pavement in surface treatment. The performance of the ultra-thin asphalt pavement was evaluated through wheel loading tests, such as Hamburg wheel-tracking and third-scale model mobileloading simulator (MMLS-3). RESULTS : An optimum binder content of 4.9% was obtained in the ultra-thin asphalt mixture from the Marshall mix design. The waterresistance tests indicated a 70% dynamic immersion coverage rate of the ultra-thin asphalt pavement. The wet track abrasion test showed an abrasion rate of 0.0107 g/cm2, and the cohesion tests indicated a 19.0 kg·cm average cohesion at 30 min of operating time and 21.4 kg·cm average cohesion at 60 min of operating time. From the Hamburg wheel-tracking test, a 16.56 mm rut depth at 20,000 wheel passing was obtained. Finally, a 5.87 mm rut depth at 300,000 number of wheel passing was detected from the MMLS-3 test. CONCLUSIONS : The water-resistance of the ultra-thin asphalt pavement satisfied the recommended guidelines of the Korean Ministry of Land, Infrastructure and Transport. In addition, the applicability of the ultra-thin asphalt pavement as a surface treatment met the standard of the International Slurry Surfacing Association. Furthermore, the deformation performance of the ultra-thin asphalt pavement was 1.5 times better than that of the straight asphalt pavement, based on the results of the wheel-loading tests. Hence, it is estimated that an ultra-thin asphalt pavement has a high performance in the preventive maintenance of asphalt pavement, even though the cracking resistance was not evaluated in this study.

PURPOSES: The objectives of this study are to analyze the current status of pothole during a rainy season and to suggest a future pavement maintenance method via pothole analysis. METHODS: Potholes are caused by moisture submerged in pavement. The pore pressure caused by traffic and environmental loads causes failure between the aggregate and asphalt binder. Thus, heavy rain is a primary pothole creator, especially in aged pavement. To prevent accidents on roadways, Gyeonggi-do has initiated a fast pothole repair program. However, the number of potholes increase every year. In this study, the current status of potholes and maintenance methods are analyzed. Based on these results, a future pavement maintenance method is suggested. RESULTS AND CONCLUSIONS : Gyeonggi-do’s pothole situation is worse than Seoul’s. Problems were founded, as follows. The amount of potholes was large, and the number increased annually. Pothole management is done at a basic level, because there is no long-term plan. Potholes occur frequently at the same site because of the poor quality of emergency repair. Finally, there is no systematic and comprehensive pavement management. Thus, pothole prevention measures are ill-prepared. Therefore, to reduce potholes and to manage high quality pavement, it is necessary to make a long-term pavement management plan.

PURPOSES: Case studies of an asphalt-overlay project with a performance-based contract method were conducted on a national highway in Korea to evaluate the effect of the method on asphalt pavement maintenance. This study evaluated the procedure of the performance-based contract method. METHODS: In this study, an asphalt-pavement maintenance project for a national highway was assessed with a performance-based contract to investigate the advantage of the new contract procedures. This is the first trial applying the performance-based contract to a pavementrehabilitation project in Korea. In the four case studies, the warranty period of the performance-based contract was designed for seven years. The research team monitored the construction site to compare the normal contract method with the performance-based contract method. The case studies’project sites were investigated after the end of the construction. RESULTS : Based on the limited case studies, the performance-based contract method could extend the service life of the asphalt pavement and reduce the pavement-maintenance budget because the quality control was well managed by the contractors. However, a few construction laws would be necessary to apply the performance-based contract method in the future. CONCLUSIONS : Using the performance-based contract, the construction company made great efforts to guarantee the warranty period and to apply the optimal maintenance method, based on the pavement distress condition. The contractor and the agency would need to understand the new performance-based contract system for it to be activated. Therefore, a proper education program for the performancebased contract system would be needed to educate the stakeholders regarding the procedures and their effects on the pavement management and maintenance.

PURPOSES:The objectives of this study are to develop a new cold-applied crack sealant and to evaluate its properties and field applicability by comparing with other conventionally used crack sealants.METHODS :A new cold-applied crack sealant was developed by using neoprene latex to improve material properties. The fundamental properties such as viscosity, residue %, penetration, and softening point of the developed crack sealant were tested by TxDOT criteria to evaluate crack sealing capability. Moreover, the performance of the developed cold-applied crack sealant was evaluated under both laboratory and field conditions. In the laboratory, the bond property was evaluated using the developed cold-applied crack sealant and conventional hotapplied crack sealant by the bond-properties test standardized under ASTM D 6690. In the field, test sections were constructed on three areas: a trunk road, bus-only lane, and motorway, with the developed crack sealant and three conventional crack sealants. After construction, early field-inspection was performed on the test sections.RESULTS AND CONCLUSIONS :Overall, the developed cold-applied crack sealant demonstrates reasonable storage stability, durability, and bond property compared to conventional hot-applied crack sealants. From the test sections, it was established that the developed cold-applied crack sealant does not pose construction issues. Moreover, the early performance was verified through field inspection. However, as the field inspection was conducted a week after the construction, it is necessary to conduct an inspection of performance from a long-term point of view.

PURPOSES: This study focuses on conducting pavement rehabilitation for more deteriorated roads given a limited government budget. METHODS: Therefore, we apply a optimization programming model of the permutation algorithm used for rehabilitating more deteriorated pavement areas, which is subjected to the limited budget. RESULTS: The permutation algorithm was evaluated in terms of determining the maximized rehabilitation of deteriorated pavement areas, using the newly developed performance models such as fatigue cracking, rutting, international roughness index(IRI) through the surveying data from 2006 to 2012. When compared with a traditional model of the so-called worst-first sequence(WFS) method, the permutation algorithm worked better than the WFS method, resulting in covering more deteriorated pavement areas given the limited government budget. CONCLUSIONS : Through a case study, it could be concluded that the permutation algorithm provides more reliable results in terms of rehabilitating more deteriorated pavement areas given the limited budget.

PURPOSES: Surface treatment is a favorable method in the pavement preventive maintenance. This study (Part Ⅰ) aimed to develop the low viscosity filling material for waterproof characteristics and high penetrable and weather resistance, and a series of companion study (Part Ⅱ) presents the coating characteristics and performance analysis using field and lab tests. METHODS : Hydrophobic characteristics of the advanced surface treatment material are observed and measured the filling depth and the permeability for sand and asphalt pavement specimen using the water absorption test and permeability test, X-RAY CT test. Color difference for the weather resistance using ultraviolet ray accelerated weathering test is compared with asphalt pavement specimens. RESULTS : The developed material shows the decreased water absorption and increased impermeable effect because of the hydrophobic characteristics. It is found that the filling depth is about 6mm and weather resistance is better than asphalt pavement specimen. CONCLUSIONS: The advanced hydrophobic - low viscosity filling treatment material is developed in this study (Part Ⅰ) to improve the waterproof characteristics and high filling capacity and weather resistance for the pavement preventive maintenance.

PURPOSES : Surface treatment material for pavement preventive maintenance should be inspected field applicability. This study(Part Ⅱ) aimed to checkup coating characteristics and performance analysis using lab and field tests. The hydrophobic - low viscosity filling material for pavement preventive maintenance is presented in Part Ⅰ, which is a series of companion study. METHODS: Relative comparison between general asphalt mixtures and surface treatment asphalt mixtures are analyzed and measured for the field application such as indirect tensile strength ratio(TSR), abrasion resistance, crack propagation resistance, temperature resistance, coating thickness, permeability resistance and skid resistance in terms of british pendulum number(BPN). RESULTS: It is found that TSR, crack propagation resistance and permeability resistance is increased as against uncoated asphalt specimen. Abrasion resistance and temperature resistance is secured from the initial coating thickness point of view, which is about 0.2~0.3mm. Skid resistance on the surface treatment pavement is satisfied with the BPN criteria of national highway because of exposed aggregate and crack sill induced pavement deterioration and damage cracks. CONCLUSIONS : The hydrophobic - low viscosity surface treatment material for pavement preventive maintenance is validated on field applicability evaluation based on quantitative analysis of coating thickness and performance analysis using lab and field tests.

PURPOSES : This study aims at proposing the methodology for benefit evaluations in pavement maintenance methods and timings using KoPMS(Korean Pavement Management System) software which was developed for efficient pavement management. METHODS : This study classified pavement sections into 4 clusters considering AADT(Annual Average Daily Traffic) and ESAL(Equivalent Single-Axle Load) using cluster analysis and used the deterioration models in each cluster. Increased user costs due to pavement deterioration as time goes by and agent costs for maintenance were estimated. Based on deterioration model and KoPMS software, Methodology for benefit evaluation was proposed in pavement maintenance methods and with/without implementation using real pavement section data. RESULTS : This study verified that considering agent costs only would be constrained to decide pavement maintenance methods and timings, and ascertained that decision making with agent and user costs would be effective. In addition, this study revealed that pavement maintenance methods and timings can be affected by AADT and ESAL and frequent pavement maintenances can be more efficient for benefits in pavement sections with more AADT and ESAL. Also this study found that user costs would be more affected to decision making than agent costs. Moreover, Delay of conducting pavement maintenance caused increased vehicle operating costs and environmental costs because of poor conditions of pavements. CONCLUSIONS : This study proposed LCCA and benefit estimation methodology of pavement with considering agent and user costs. The results of this study can be used for baseline data of efficient pavement asset management.