• International Journal of Highway Engineering
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• v.14 no.5
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• pp.31-45
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• 2012

PURPOSES: In Korea, rapid maintenance of distressed concrete pavement is required to prevent traffic jam of the highway. Asphalt concrete overlay has been used as a general maintenance method of construction for aged concrete pavement. AC overlay on existing concrete pavements experience various early distresses such as reflection crack, pothole and rutting, due to different physical characteristics between asphalt overlay and existing concrete pavement. Bonded concrete overlay(BCO) is a good alternative since it has advantages that can reduce various distresses during the service life since overlay material has similar properties with existing concrete pavements. Recently, BCO which uses the ultra rapid harding cement has been applied for maintenance of highway. BCO has advantage of structural performance since it does monolithic behave with existing pavement. Therefore, it is important to have a suitable bond strength criteria for securing performance of BCO. Bond strength criteria should be larger than normal tensile stress and horizontal shear stress occurred by traffic and environmental loading at bond interface. Normal tensile stress and horizontal shear stress need to estimated for the establishment of practical bond strength criteria. METHODS: This study aimed to estimate the bond stresses at the interface of BCO using the three dimensional finite element analysis. RESULTS: As a result of this study, major failure mode and maximum bond stress are evaluated through the analysis of normal tensile stress and horizontal shear stress for various traffic and environmental load conditions. CONCLUSIONS: It was known that normal tensile stresses are dominated by environmental loading, and, horizontal shear stresses are dominated by traffic loading. In addition, bond failure occurred by both of normal tensile stresses and horizontal shear stresses; however, normal tensile stresses are predominated over horizontal shear stresses.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.1-11
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• 2009

This study focuses on evaluating the applicability of an acryl based polymer concrete to the thin bridge deck pavements. The acryl concrete developed in this study is composed of Methyl Methacrylate(MMA) resin, benzol peroxide and fillers. To study the effects of the types and amounts of the components on the physical characteristics of the acryl concrete, viscosity, compressive strength and bending tests were conducted. The optimum mixture design was then determined based on the testing results. Several different types of laboratory tests, such as water and chlorine ion penetration tests, shrinkage and thermal coefficients tests, and tensile bonding strength tests were performed for the optimum acryl concrete and conventional cement concrete. The testing results show that water and chroline ion resistance, bonding strength between acryl and cement concrete and crack resistance of the acryl concrete is better than those of the conventional cement concrete. There are shortcomings that the conventional acryl concrete has a higher shrinkage and thermal coefficients. However, it was confirmed that to use newly developed rubberized MMA resin in this study reduces the crack resistance with substantially increased ductility.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.65-70
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• 2008

Asphalt concrete pavements are susceptible to deformation and failure compared to cement concrete pavements. Epoxy is commonly used to enhance the bonding and durability of structures. Based on this concept, an epoxy and ceramics combined mixture was developed and applied to the field to estimate the pavement performance, Laboratory and field performance tests were conducted to observe the applicability of epoxy and ceramics composite materials compared to the conventional one. In this research, the epoxy and ceramics composite mixturewas used in two ways. 7 mm and 15 mm of thin surface layers using the mixture were constructed on cement and asphalt concrete pavements, respectively, after surface treatment. 12 months of field performance surveys were conducted to observe the resistances to the crack and deformation. According to the field performance tests, epoxy and ceramics combined mixture showed better bonding and field performances than the conventional one.

• International Journal of Highway Engineering
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• v.12 no.1
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• pp.47-54
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• 2010

This study had a focus on investigating technical validity of Two-Lift Concrete Pavements which had never been constructed in Korea in order to olve the problem of existing concrete pavements. This study found out the application of Steel Fiber Reinforced Concrete (SFRC) which was one of ew techniques. Also, optimal steel fiber contents and pavement thickness were determined. This study also measured compressive strengths, lexural strengths, toughness indexes, tensile strengths and fatigue strengths to estimate the performance of SFRC of according to results of aboratory experiments, slumps and air contents of concrete specimens the standards satisfied and compressive strengths to open traffic. At bending ests, Toughness Index of SFRC increased but flexural strength didn’'t increase as compared with non-steel fiber concretes. And, energy absorption of SFRC was very good and SFRC showed improvement in freezing and thawing resistances. To complete this research, we will evaluate the pplication methods and performance of SFRC at field section.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.45-54
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• 2006

The Construction policy of government ever since 1970s have brought the economical growth, but has been causing environmental problems. Most roads were paved either asphalt concrete or portland cement concrete. These types of pavements has caused to rise temperature by making local heat islands in urban during summer time. Recently the wet-mixing solidified soil pavement, a kind of soil-cement, has developed and has been applied to the environment-oriented pavement. The solidified soil wet-mixed is placed on the subgrade along with asphalt concrete and portland cement concrete. Thermistors are laid in these field test pavements. The temperature gradients of these pavements are automatically measured with time. As the results of this test, the equation estimating surface temperature of pavement is proposed by analyzing measured temperature data. It is shown that the temperature change within the surface layer due to the change of air temperature is the greatest in the asphalt mixture and the least in the solidified soil mixture. Since it is proven that this wet-mixing solidified soil pavement emit less radiant heat than other existed pavements. Therefore this type of pavement can be successfully applied to the roads, such as walks, parkways, and bikeways, which are required to be human-friendly and environment-oriented.

• Structural Engineering and Mechanics
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• v.40 no.2
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• pp.149-165
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• 2011

In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic $150{\times}150{\times}150$ mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using a soil-based compaction method and the optimum moisture content obtained from the pertaining experiments, and by adding different percentages of Iranian pozzolans as well as different amounts of steel fibers, each one accompanied by 0.1% of poly-propylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease, but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers, but neither steel nor PP fibers did contribute to increase in the rupture modulus independently. Also, the toughness indices increased when steel fibers were used.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.5
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• pp.1-10
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• 2007

A laboratory investigation is conducted to characterize and quantify fatigue lives of continuously reinforced concrete pavements (CRCP) with initial design parameters. Eight specimens scaled were made based on results of finite-element analyses and stress-strain curve comparisons. Static tests were firstly performed to obtain magnitudes of static failure loads and to predict crack patterns before fatigue tests. The fatigue lives measured in the study were compared based on each initial design parameter. The comparison indicates that the fatigue lives of CRCP specimens with initial cracks increases with increasing the initial crack spacing, and CRCP specimens with reinforcements at top of the concrete slab have more fatigue lives than those with reinforcements at midheight of the concrete slab. In addition, the fatigue lives were significantly affected by soil conditions under the CRCP specimens. The results obtained in the study can be used for maintenance and retrofit of the continuously reinforced concrete pavements.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.493-498
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• 1999

Many concrete pavements closed to the end of service life in out country need to repair. We investigated material and mix designs for thin bonded concrete overlay and applied it to concrete pavement rehabilitation. The concrete with Type III cement showed earlier strength and better durability than the concrete with Type I cement. Designed concrete mixture with TypeIII cement made it possible to open the road earlier against heavy vehicles, increased traffic despite of cold weather in winter. In the field examination after four month, there was no defects like as shrinkage crack, spalling, surface abrasion and scaling, and good traffic condition has been maintained.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.125-129
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• 2004

Hydrating concrete pavement is typically subjected to temperature-induced stresses that drive cracking mechanisms at early concrete ages. Undesired cracking plays a key role in the long-term performance of concrete pavement systems. The loss of support beneath the concrete pavement due to curling caused by temperature changes in the pavement may induce several significant distresses such as punch out pumping, and erosion. The effect of temperature on these distress mechanisms is both significant and intricate. Because thermal conductivity dominates temperature flow in hydrating concrete over time, this material property is back-calculated by transforming governing equation of heat transfer and test data measured in laboratory. Theoretically, the back- calculated thermal conductivity simulates the heat movements in concrete very accurately. Therefore, the back- calculated thermal conductivity can be used to calibrate concrete temperature predicted by models.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.507-512
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• 2002

In road pavements, it is known that cement concrete pavement has superior durability. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We developed special cement developing 1 day strength of over 30.0N/$mm^2$ to open the road within 1 day and workable time is maintained over 1 hour so that it can be used as ready mixed concrete. We performed experimental overlay construction with concrete and evaluated the properties of the fresh and hardened concrete. The flexural strength was over 5.0N/$mm^2$ and the compressive strength was over 30N/$mm^2$ at 1 day. So it is thought that the road can be open to traffic within 1 day after placement.