• 한국도로학회지:도로
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• v.5 no.4 s.18
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• pp.36-46
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• 2003

포장구조체에서 요구되는 강도를 갖게 하는 구조 설계의 방법은 경험적 절차부터 반역학적 절차까지 발전되어 왔다. 재생 가열아스팔트혼합물이 기존의 가열아스팔트혼합물(HMA)과 비교하여 비슷하거나 때에 따라 더 좋은 성능을 가져오므로, AASHTO설계지침서에서는 본질적으로 재생(recycled) HMA 재료와 신생(virgin) HMA 재료간의 차이가 없다고 기술하고 있으며, 기존 HMA 재료에 사용되는 덧씌우기설계법의 구조회복 분석방법(structural rehabilitation analysis method)을 재생포장설계에도 권장하고 있다. 재생 가열아스팔트의 설계를 위한 AASHTO 방법은 설계교통량, 교통량 및 수행능력예측의 신뢰수준, 공용기간, 그리고 포장상태 평가지수에 의하여 결정된 포장구조체에서 요구되는 포장두께지수(SN)에 기초한다. 포장두께지수(SN)는 포장층 두께, 상대강도계수, 각 층의 배수조건들의 곱의 조합으로서 나타내어질 수 있다. 덧씌우기로 간주될 수 있는 재생된 층의 포장두께지수(SN)는 기존 포장에서의 포장두께지수와 보강된 포장에서 요구되는 포장두께지수의 차이에 의하여 계산되어질 수 있다. 상대강도계수의 값은 AASHTO 설계지침에 명시되어 있다. AI 방법은 교통량, 노상의 회복탄성계수, 그리고 설계두께를 계산하기 위한 표층과 기층의 종류를 사용한다. 이 방법은 재생된 가열혼합물질과 기존의 가열혼합물질과는 거의 비슷한 성능을 나타낸다고 본다. 또다른 AI 방법에 의하면 재생된 층은 덧씌우기층이라고 간주하고, 현재의 포장두께와 요구되어지는 포장두께 사이의 차를 이용하여 재생될 층의 두께를 산정한다. 소요되는 덧씌우기 두께는 포장의 현장 상태지수(condition rating)와 각 종류에 따른 포장체와 포장재료가 아스팔트 콘크리트층의 등가두께로 전환되어 나타나는 방법에 근거하여 결정될 수 있다. 또 다른 방법은 포장체 각 층의 물성과 하중을 이용한 컴퓨터 프로그램에 의하여 산정된 하중-변형 응답에 의한 설계 방법을 포함한다. 이런 방법들에서는 포장체는 탄성이나 점탄성층 위에서 탄성이나 점탄성 거동을 보인다고 가정한다. 재생 상온혼합물에서의 AASHTO 설계 방법은 가열혼합물의 설계방법과 유사하다. 그러나, 재생 상온혼합물에서의 상대강도계수는 시공방법에 좌우되므로, 기술자의 판단을 근거로 하여 결정되어져야 한다. AI방법에서는 포장구조체를 다층탄성구조라고 보고, 노상의 강도와 설계 교통량을 근거로 요구되는 포장두께를 결정한다. 재생 상온혼합물 기층의 두께는 재생 상온혼합물 기충 위에서 가열아스팔혼합물에 대하여 산정된 덧씌우기 두께를 이용하여 결정할 수 있다. 아스팔트 표면의 재생은 기존 포장의 구조적 능력을 정상적으로 개선할 수 없으므로, 표면 재생의 두께를 설계하는 방법은 없다. 그러나, 임의의 덧씌우기 두께는 기존의 덧씌우기 설계법에 기초하여 산정 할 수 있다. 만약 덧씌우기가 승차감만을 개선시킨다고 여겨진다면, 혼합물에서 사용되어지는 최대 골재 크기에 기초한 최소 두께를 결정할 수 있다.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.41-48
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• 2011

Warm-Mix Asphalt(WMA) mixtures, which meet environmental protection and have high energy efficiency, are emerging as an alternative to hot-mix asphalt mixtures. The objective of this study is to evaluate WMA made with Aspha-min in the laboratory and to compare the design results accomplished by new Mechanistic-Empirical Pavement Design Guide(MEPDG) with control mixture. An asphalt mixture with a nominal maximum size of 12.5mm and PG64-28 binder was used. Resilient modulus tests for a control mixture and WMA with 0.3% and 0.5% of Aspha-min were conducted. The results obtained by MEPDG after inputting the test output into the design indicated that the predicted rut depth of WMA using Aspha-min was much lower than that of control mixture, and showed that WMA was more resistant to rutting than control mixture.

• The Korean Journal of Applied Statistics
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• v.20 no.2
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• pp.267-280
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• 2007

Various single-valued design optimality criteria such as D-, G-, and V-optimality are used often in constructing optimal experimental designs for mixture experiments in a constrained region R where lower and upper bound constraints are imposed on the ingredients proportions. Even though they are optimal in the strict sense of particular optimality criterion used, it is known that their performance is unsatisfactory with respect to the prediction capability over a constrained region. (Vining et at., 1993; Khuri et at., 1999) We assume the quadratic polynomial model as the mixture response surface model and are interested in finding efficient designs in the constrained design space for a mixture. In this paper, we make an expanded list of candidate design points by adding interior points to the extreme vertices, edge midpoints, constrained face centroids and the overall centroid. Then, we want to propose a robust design with respect to D-optimality, G-optimality, V-optimality and distance-based U-optimality. Comparing scaled prediction variance quantile plots (SPVQP) of robust designs with that of recommended designs in Khuri et al. (1999) and Vining et al. (1993) in the well-known examples of a four-component fertilizer experiment as well as McLean and Anderson's Railroad Flare Experiment, robust designs turned out to be superior to those recommended designs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4832-4836
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• 2012

In general, there are needed lots of time and experiments for determination of optimum asphalt content and mix design. The experimental results are highly depended on the skill of testers. Bailey suggested the proper aggregate gradation of hot mix asphalt are a function of special size and passing percent of the specified aggregate to reduce the test errors. In this paper, the asphalt mix designs of 19mm dense graded mix and PA-20mm for FHWA were carried out, using Bailey's method. The use of Bailey method can cut down the testing times to get the proper aggregate gradation for asphalt mix design. In case of 19mm dense graded asphalt mixture, the measured values of CA, $FA_c$, $FA_f$ are 0.724, 0.440, and 0.455, which are within the suggested values by Bailey. Also, in case of PA-20 graded asphalt mixture, the measured values of CA, $FA_c$, $FA_f$ are 0.646, 0.476, and 0.450, respectively.

• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.28-34
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• 2006

In general engineering problems, the purpose of an optimization is to get optimal design variables. It is the same problem to fix the total amount of the design variables and to judge the optimal mixing proportions of the design variables. That is to say, we can recompose the engineering problems in the concepts of the mixture amount experiments. The goal of mixture amount method is to get the response surfaces of varying both the mixing proportion of component and the total amount of the mixture. The solution of the aircraft fuselage optimization problem is obtained by the mixture amount method and genetic algorithm. In this study, it is shown that the mixture amount method can be utilized for the aircraft structural optimization problem. Also, this method in this study can be applied for the optimization problems over 12 design variables which is impossible for D-optimal design.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.181-187
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• 2008

This paper presents the results of the effects on the inclusion of the pigment in the color asphalt mixture. The particle size of the pigment is extremely finer than that of the filler and should be reduced the amount of the filler used. It was found in the present practise that the total weight of 2% of the pigment in the weight of the total aggregate was used during the mix design. The extra inclusion of the pigment in the mixture increased the amount of the filler and affected on the volumetric properties such as void ratio and VMA. It has related with the performance and distress of the pavement and found that the mechanical properties have decreased.

• 한국도로학회지:도로
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• v.2 no.4 s.6
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• pp.37-49
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• 2000

이 보고서는 수퍼페이브의 개념으로 설계된 혼합물이 시방규정에 만족하기 위하여 꼭 필요한 혼합물의 생산, 포설 및 다짐에 대한 내용을 정리한 것이다. 이 보고서 단독으로는 큰 의미가 없으며, 기존의 일반적인 혼합물에 사용되었던 훌륭한 시공기술이 동시에 사용되어야한다. 수퍼페이브가 적용됨으로 해서 발생되는 혼합물의 가장 큰 변화는 굵은입도의 혼합물사용 및 보다 많은 양의 모난골재사용 그리고 개질아스팔트의 사용 등이다. 이러한 변화들은 약간의 시공순서의 수정을 필요로 하게 된다. 이 보고서는 이러한 것에 대한 몇 가지 제안을 포함하고 있다.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.65-73
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• 2004

Marshall stability and flow don't reflect mechanical property of asphalt mixtures and have little correlation with rutting-related performance. There is often rutting occurred on the asphalt pavement which was constructed using a mixture passing the specification for stability and flow. This study dealt with comparison of volumetric properties of mixtures from Marshall mix design and from Superpave mix design. This study used one binder, three aggregates and two gradations. The mixtures were manufactured by each mix design method. Result showed that OAC, VMA and VFA by Marshall mix design were higher than those by Superpave mix design. This is because Mashall mixture has the gradation prone to rutting and it should be further investigated whether or not the high OAC is direct cause of rutting in asphalt pavement.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.3
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• pp.59-67
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• 2007

For the time being, HMA test specimen were prepared by Marshall Compaction Method for hot mix asphalt design and evaluated the mechanical properties of HMA at the specified air voids. Gyratory Compaction can simulate the field compaction process and measure the degree of compaction just after field compaction in laboratory. Superpave mix design with Gyratory compactor has been used for characterization of performance. The curve of gyratory compaction can be used to evaluate the permanent deformation potential of hot mix asphalt. In this paper, couple of indices for hot mix asphalt have been showed for hot mix asphalt in Korea. The major properties from gyratory compaction curve are compaction energy index and traffic compaction index. The specific guide line for the potential of hot mix asphalt has been proposed.