• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.491-498
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• 2012

This study examines setting shrinkage, coefficient of thermal expansion, and elastic modulus of unsaturated polyester( UP)-methyl methacrylate(MMA) polymer concrete, which is generally used for repair of portland cement concrete pavement and manufacturing of precast products. In this study, a series of laboratory test were conducted with variables such as UP-MMA ratio, shrinkage reducing agent (SRA) content, and test temperature. The results showed that the setting shrinkage ranged from 29.2 to $82.6{\times}10^{-4}$, which was significantly affected by test temperature. Moreover, the findings revealed that the coefficient of thermal expansion, elastic modulus and ultimate strain of UP-MMA based polymer concrete ranged from 21.6 to $31.2{\times}10^{-6}/^{\circ}C$, 2.8 to $3.3{\times}10^4$ MPa, and 0.00381 to 0.00418, respectively. The results of this study will be used as important data for design and application of UP-MMA based polymer concrete.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.9-20
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• 2011

Most of domestic expansion joint system was applied by exposed expansion joint system. There are cases where it is damaged by driving. As the result noise and impact happened, and the social cost due to frequent repair works is increasing. So based on the Asphalt Plug Joint(APJ) system that applied in the United States and Europe, new buried expansion joint system was lately developed a system of Buried Folding Lattice Joint(BFLJ) that changed substructure. In this research, we have tested for durability and flexibility performance of buried expansion joint system that based on the type of asphalt mixture. Also we have evaluated for durability of BFLJ system against vehicle load using accelerated pavement testing. As a result of the experiment, the developed BFLJ system gives high flexibility performance and resolves transformation concentration along the joint section more than APJ system. Also it could be seen that the BFLJ system could overcome the disadvantages of APJ and prevent early damage. Because surface deflection of BFLJ system against vehicle load was measured low, and sub system in the buried expansion joint system was not damaged against vehicle load.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.177-183
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• 2011

VES-LMC(very-early strength latex modified concrete) has been widely used as repair material for bridge deck overlay or rehabilitation, because it could be opened to the traffic after 3 hours of curing. However, the bright color of VES-LMC disturb driver's sigh. A black VES-LMC, matching to asphalt concrete, was developed and applied at a filed for driver's comfort and safety. The black VES-LMC included 2% carbon black in cement weight ratio. A series of performance evaluation for black VES-LMC was done in terms of field applicability, pavement color and temperature change. The field applicability test result showed that there were no change of workability, slump and air void, and the compressive strengthen developed more than 20MPa after 4 hours of placement. The thermal stress of black VES-LMC was smaller than that of OPC and asphalt concrete, which means the stability of black VES-LMC. The performance evaluation result showed that the black VES-LMC could prevent road icing at below zero temperatures and promote thawing at melting temperature.

• Magazine of the Korea Concrete Institute
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• v.9 no.4
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• pp.197-205
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• 1997

The shrinkage of polymer concrete overlays to cement concrete causes interface shear, normal and axial stresses in the overlays. These can lead to deterioration of the polymer concrete overlays due to affection of adhesion polymer concrete and cement concrete. The shrinkage stress in the polymer concrete cause it to shorten and the shorting is measured: With the modulus of elasticity of the polymer concrete and strain known the stresses can be calculated. The purpose of this study is to provide the basic data of application of polymer concrete overlays such as bridge decks, highway and airport pavement repair and overlay materials. From the test results. It has been found that depending on the type polymer. overlay thickness, time after curing and temperature. the shrinkage stresses are eliminated by relaxation in time ranging from a few hours to a few days.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.127-133
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• 2013

PURPOSES : The impact performance of flexible barrier system such as structural response, vehicular motion and occupant safety vary depending on the impact point. Thus, to properly evaluate the performance of a flexible barrier system, impact should be made to a point which will lead to the worst possible results. This point is called the Critical Impact Point (CIP). This paper presents the way to determine the CIP for a SB2 class flexible barrier system which is consisted of Thrie-Beam rail and circular hollow tube post of 2m span. METHODS: Barrier VII simulations were made for impact points; Case 1 at a post, Case 2 at 1/3 span downstream from a post, Case 3 at middle of the span, Case 4 at 2/3 span downstream from a post. For the structural performance (deflections), impact simulation of 8000kg-65km/h-15degree was used, and for vehicle motion and occupant safety, simulation of 1300kg-80km/h-20degree impact was made and analysed. RESULTS: Case 1 gave the largest dynamic deflection of 75.72cm and also gave the largest snag value of 44.3cm. Occupant safety and exit angle of the vehicle after the impact were not sensitive to the impact point and were all below the allowable limit. CONCLUSIONS : For the SB2 class flexible barrier system's CIP can be regarded as a post which is sufficiently away from the end of Length of Need in order to avoid the end-effect of the barrier system. It can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Journal of the Korean Institute of Rural Architecture
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• v.17 no.2
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• pp.51-58
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• 2015

10 years ago, in Sijeon-ri, Dogo-myeon, Asan-si, the existing stream was repaired to develope Mt. Dogo trail and irrigation systems through road expansion pavement construction and small stream repair construction. The trees such as persimmon and willow are eliminated that rowed on both sides of the stream and dredging work to dig the rock and sand have been performed. As a result, wide asphalt road was built, also flood damage worries were reduced. 10 years passed and now, how did local residents think about the stream repaired before and after? Village residents, public officials, and the stream construction engineer were interviewed. Villagers indicated a problems that brook became a place where water peppers were taking over and water was stagnating due to the slow velocity so nothing could live and natural landscape like a wash place and the cascade disappeared, because rock and sand were taken out brought soil into the brook. Public officials and engineers were aware of the problems at the time of the stream. Now that construction is completed after 10 years, Both realistically and budgetary to restoration would be difficult. However, it is necessary to seek for waterfront space which can be restored or replaced by a part of the stream like similarly before. In addition, it is necessary to restore to the progression of a natural stream which connect with stairs(or slope) - small waterfalls - pools - wash place. In this paper, we hope to take a lesson from the Sijeon-ri model and make rural stream construction be prepared with consideration about not only distinct characteristics of specific area but also the opinion of local resident.

• Structural Engineering and Mechanics
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• v.90 no.5
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• pp.467-480
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• 2024

The mechanical properties and durability of concrete pavements may be degraded in extreme situations, resulting in the need for partial repair or total replacement. During the past few decades, there has been a growing body of research on substituting a portion of Portland cement with alternative cementitious materials for improving concrete properties. In this study, two different configurations of powdered and granulated blast furnace slag were implemented, replacing fine aggregates (by 12 wt.%) and Portland cement (by 0, 20, 40, and 60 wt.%) in the making of roller-compacted concrete (RCC) mixes. The specimens were fabricated to investigate the mechanical properties and durability specifications, involving freeze-thaw, salt-scaling, and water absorption resistance. The experimental results indicated that the optimum mechanical properties of RCC mixes could be achieved when 20-40 wt.% of powdered slag was added to concrete mixes containing slag aggregates. Accordingly, the increases in compressive, tensile, and flexural strengths were 45, 50, and 28%, in comparison to the control specimen at the age of 90 days. Also, incorporating 60 wt.% of powdered slag gave rise to the optimum mix plan in terms of freeze-thaw resistance such that a negligible strength degradation was experienced after 300 cycles. In addition, the optimal moisture content of the proposed RCC mixtures was measured to be in the range of 5 to 6.56%. Furthermore, the partial addition of granulated slag was found to be more advantageous than using entirely natural sand in the improvement of the mechanical and durability characteristics of all mixture plans.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.39-47
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• 2016

Repair methods of aging concrete pavement are generally used composite structure pavements, such a composite structure is subjected to a large impact on the mechanical behavior and ensure long-term commonality integrated under vehicle loads, environmental loads of the public in accordance with the bond strength between old and new concrete. A common of bonded concrete overlays that are currently available is Interface arrangements using a variety of equipment to ensure the excellent bond strength between old and new concrete than standard concrete, mixed with a material such as a polymer in order to improve the adhesion with the material itself. However, these method of constructions are being applied, depending on the developer site presents no special specifications apply when a specific application criteria objectively, this is due to the situation of each individual method, which is based on the difficulty in quality control of the site manager. In this study by performing a field test for polymer content via the variables that contribute most significantly to ensure bond strength and the field element core of the interface processing method and materials to ensure bond strength between the old and the new concrete, it was to derive the construction site construction method that can improve the performance of the bond strength through a review of the construction around the correlations and the bond strength according to the effective performance analysis of the conventional surface treatment process and variation of polymer volume fraction.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.43-49
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• 2002

Asphalt pavements have to perform under the conditions of heavily-loaded vehicles due to the industrialization and large temperature variance between the summer and the winter. Due to these factors, a characteristics change of early permanent deformation becomes a big issue, and to remedy this problem many research to use modified asphalt are being widely conducted. However, most of the modified asphalt is being paved after milling the surface course and applying tackcoating, and it is being used mostly for the repair and maintenance purpose rather than pavement of new national road. The purpose of this investigation is to obtain some fundamental data for the evaluation of the performance and long-term performance of the construction material mixtures by the laboratory test and field experiments. For the field experiment, 200m of two-lanes national road, that is being paved for the new national road under the direction of Pusan Regional Construction Management Office, was paved with SBS PMA and PSMA asphalt mixtures, which are an modified asphalt mixtures used for the surface course, on top of the base course paved with other modified asphalt mixtures. The remaining section of the new national road was paved with dense grade mixture. The laboratory tests assessed and analyzed the mixture characteristics by Marshall's stability test, strength tests and wheel-tracking test. On the basis of the evaluation result of the temperature control and roughness of the newly constructed road at the field experiment site, it is desired to evaluate and identify the most economic modified asphalt mixtures by long-term performance evaluation and LCC(Life Cycle Cost) analysis in order to apply the test result to the design of new road construction in the future.

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.85-95
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• 2015

PURPOSES : Recently, bonded concrete overlay has been used as an alternative solution in concrete pavement rehabilitation since its material properties are similar to those of the existing concrete pavements. Deteriorated concrete pavements need rapid rehabilitation in order to prevent traffic jams on Korean expressways. Moreover, speedy and effective repair methods are required. Therefore, the use of bonded concrete overlay with ultra-rapid hardening cement has increased in an effort to reopen promptly the expressways in Korea. However, mobile mixer is required for ultra-rapid hardening cement concrete mixing in the construction site. The use of mobile mixer causes various disadvantages aforementioned such as limitation of the construction supply, open-air storage of mixing materials, increase in construction cost, and etc. In this study, therefore, hydration accelerator in-situ mixing on polymer modified concrete produced in concrete plant is attempted in order to avoid the disadvantages of existing bonded concrete overlay method using ultra-rapid hardening cement. METHODS : Bonded concrete overlay materials using ultra-rapid hardening cement should be meet all the requirements including structural characteristics, compatibility, durability for field application. Therefore, This study aimed to evaluate the application of hydration accelerator in-situ mixing on polymer modified concrete by evaluating structural characteristics, compatibility, durability and economic efficiency for bonded concrete overlay. RESULTS : Test results of structural characteristics showed that the compressive, flexural strength and bond strength were exceed 21MPa, 3.15MPa and 1.4MPa, respectively, which are the target strengths of four hours age for the purpose of prompt traffic reopening. In addition, tests of compatibility, such as drying shrinkage, coefficient of thermal expansion and modulus of elasticity, and durability (chloride ions penetration resistance, freezing-thawing resistance, scaling resistance, abrasion resistance and crack resistance), showed that the hydration accelerator in-situ mixing on polymer modified concrete were satisfied the required criteria. CONCLUSIONS : It was known that the hydration accelerator in-situ mixing on polymer modified concrete overlay method was applicable for bonded concrete overlay and was a good alternative method to substitute the existing bonded concrete overlay method since structural characteristics, compatibility, durability were satisfied the criteria and its economic efficiency was excellent compare to the existing bonded concrete overlay methods.