• International Journal of Highway Engineering
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• v.11 no.1
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• pp.1-12
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• 2009

A new mix design procedure for cold in-place recycling using foamed asphalt (CIR-foam) has been developed for Iowa Department of Transportation. Some strengths and weaknesses of the new mix design parameters were considered and modified to improve the laboratory test procedure. Based on the critical mixture parameters identified, a new mix design procedure was developed and validated to establish the properties of the CIR-foam mixtures. As part of the validation effort to evaluate a new CIR-foam mix design procedure, dynamic moduli of CIR-foam mixtures made of seven different reclaimed asphalt pavement (RAP) materials collected throughout the state of Iowa were measured and their master curves were constructed. The main objectives of this study are to provide: 1) standardized testing procedure for measuring the dynamic modulus of CIR-foam mixtures using new simple performance testing (SPT) equipment; 2) analysis procedure for constructing the master curves for a wide range of RAP materials; and 3) impacts of RAP material characteristics on the dynamic modulus. Dynamic moduli were measured at three different temperatures and six different loading frequencies and they were consistent among different RAP sources. Master curves were then constructed for the CIR-foam mixtures using seven different RAP materials. Based upon the observation of the constructed master curves, dynamic moduli of CIR-foam mixtures were less sensitive to the loading frequencies than HMA mixtures. It can be concluded that at the low temperature, the dynamic modulus is affected by the amount of fines in the RAP materials whereas, at the high temperature, the dynamic modulus is influenced by the residual binder characteristics.

• 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.

• International Journal of Highway Engineering
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• v.1 no.1
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• pp.97-106
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• 1999

This study was conducted to develop a test system for evaluating resistance against reflection cracking in shear mode caused by wheel load in asphalt concrete overlaid on the deteriorated cement concrete pavement. Reflection cracking resistance of selected polymer modified asphalt(PMA) mixtures with and without reinforcement was evaluated using this test system. It was shown that the test results accounted for the effectiveness of materials and reinforcement characteristics in terms of the difference in the resistance against reflection cracking. A shear failure life of a certain mixture was estimated with a high coefficient of determination. when the test results were used in a well known prediction model. Therefore, it seemed to be possible to use this technique for predicting a relative service life of on overlay.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.49-58
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• 2017

PURPOSES : The objective of this study is to develop a simple regression model in designing the asphalt concrete (AC) overlay thickness using the Mechanistic-empirical pavement design guide (MEPDG) program. METHODS : To establish the AC overlay design equation, multiple regression analyses were performed based on the synthetic database for AC thickness design, which was generated using the MEPDG program. The climate in Seoul city, a modified Hirsh model for determining dynamic modulus of asphalt material, and a new damaged master curve approach were used in this study. Meanwhile, the proposed rutting model developed in Seoul city was then used to calibrate the rutting model in the MEPDG program. The AC overlay design equation is a function of the total AC thickness, the ratio of AC overlay thickness and existing AC thickness, the ratio of existing AC modulus and AC overlay modulus, the subgrade condition, and the annual average daily truck traffic (AADTT). RESULTS : The regression model was verified by comparing the predicted AC thickness, the AADTT from the model and the MEPDG. The regression model shows a correlation coefficient of 0.98 in determining the AC thickness and 0.97 in determining AADTT. In addition, the data in Seoul city was used to validate the regression model. The result shows that correlation coefficient between the predicted and measured AADTT is 0.64. This indicates that the current model is more accuracy than the previous study which showed a correlation coefficient of 0.427. CONCLUSIONS:The high correlation coefficient values indicate that the regression equations can predict the AC thickness accurately.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.88-94
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• 2012

In order to develop high performance concrete that overcome defects of asphalt and latex modified concrete for bridge deck overlay, this study aims to evaluate durability performance of concrete slab for bridge deck overlay. The present study is an exploratory research concerned with evaluation of two types of high performance concrete for bridge deck applications. This study is composed of a set of experiments, including static loading test and fatigue test and compared with data of defection, crack, concrete and steel strain. Also, experimental results were verified with analytical models by ABAQUS program. But overall behaviors of all specimens are comfortable, so those take sufficient load carrying capacity and high stiffness in cyclic load.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.402-408
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• 2002

The permeable polymer-modified concrete has a lot of internal voids, which has more excellent performance in permeability and durability than asphalt and cement concrete. Therefore, the purpose of this study is to ascertain the strength properties of water-permeable polymer concretes with SBR latex and redispersible polymer powder. The water-permeable polymer concretes using SBR latex and redispersible polymer powder with water-binder ratio of 29 ％, polymer-cement ratios of 0, 5, 10, 15 and 20 ％ are prepared, and tested for compressive strength, splitting tensile strength, flexural strength, water permeablility. From the test results, improvements in the strength properties of the water-permeable polymer concretes due to the addition of the SBR latex and redispersible polymer powder are discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.185-195
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• 2001

Latex Modified Concrete(LMC) has been widely used for the pavement of highway bridges over the past 35years around the world since it is more resistant to the intrusion of chloride ions, has higher tensile, compressive, and flexural strength, and has greater freeze-thaw resistance. However, in Korea, it has not been introduced to fields due to higher initial construction cost for its overlay compared with that of conventional pavement materials. Due to durable characteristics, it should be noted that the LMC may be more cost-effective than conventional pavements such as asphalt pavement, when life-cycle cost(LCC) concept is considered. The objective of this study is intended to suggest a practical LCC analysis model for pavement projects and to demonstrate relative cost-effectiveness of the LMC overlays in comparison with conventional pavement techniques. It may be stated that the procedure proposed in this study may be utilized for making optimal decision on cost-effective pavement design.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.401-408
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• 2017

In preparation of self-repairing polymer-modified waterproofing asphalt-montmorillonite (MMT) composite, silylation-modification characteristics of cation ($Na^+$) exchanged K-10 (Na-MMT-K) using 3-aminopropyltriethoxysilane (APS) were studied and the optimal conditions of its silylation-modification process were proposed by use of the results of XRD analysis on silylation-modified Na-MMT-K (S-Na-MMT-K) under various conditions. According to XRD results, it was confirmed that peaks of Na-MMT-K were simultaneously consistent with those of K-10 and natural or Ca-MMT modified Na-MMT. Similarly, S-Na-MMT-K was observed to have two basal spacings ($d_{001}$), among which the area-ratio of a secondary (001) peak ($2{\theta}=3.9{\sim}4.2^{\circ}$) to a primary (001) peak ($2{\theta}{\sim}8.838^{\circ}$) was suggested to be a criterion to represent a degree of APS silylation-modification. Then, the optimal conditions on APS-stirring period prior to APS-MMT reaction, APS-MMT reaction period, APS concentration and reaction temperature at the highest area-ratio were turned out to be 20 min, 2~3 hr, 7.5 w/v% and $50^{\circ}C$, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.931-940
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• 2015

Roller Compacted Concrete Pavement (RCCP), is a type of pavement using compaction roller and asphalt finisher on concrete mixture that contains low amount of water. RCCP strength and durability are greatly affected by compaction level. Quality control is performed by ensuring the degree of compaction at site based on dry density. In the field, Modified Proctor Test is used in order to obtain optimum dry density. However, there is no clear compaction curve analysis criteria of Modified Proctor Test for RCCP. In this study, compaction curve built by three samples of Modified Proctor Test was produced and it was used to compare with compaction curve contented lower number of samples (one and two samples) in order to analyze their reliability. Thus, a conclusion was drawn from the results; by comparing to the result from Modified Proctor Test of three samples, the use of two samples represented result with only 0.5% of error which means the reliability is 99.5%.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.653-660
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• 2007

Since the temperature of asphalt for deck plate of steel bridge during paying procedure is relatively high as $240^{\circ}C\;to\;260^{\circ}C$, the temperature of deck plate of bridge rises mere than $100^{\circ}C$ and excessive displacement and stress could occur. In order to avoid undesirable failure of base plate and determine the optimal pavement pattern, a thorough thermal analysis is needed. General structural model which is made of beam and plate element should be modified for transient heat transfer analysis; asphalt pavement material and convection effect on surface of structure need to be added. A new technique with the Equivalent Heat Source (EHS) for numerical thermal analysis for steel bridge under thermal load of Guss asphalt pavement is proposed. Since plate/beam elements which were generally used for structural analysis for bridge cannot explain convection effect easily on plate/beam surface, EHS which is determined based on calculated temperature with convection effect is used. To verify the EHS proposed in this study, numerical analyses with plate elements are performed and the results are compared with estimated temperatures. EHS might be used for other thermal analyses of steel bridge such as welding residual stress analysis and bridge fire analysis.