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Slippage cracking in asphalt overlays occurs because of bonding failure between the asphalt concrete and Portland cement concrete layers. A direct shear test was adopted to simulate common and critical bonding failures. The effects of temperature and tack coat have already been studied by previous researchers; however, the effects of texture have not been sufficiently considered. In this study, clamping shear strength was used to characterize the pure shear strength of the pavement. It is defined as the difference between the total shear strength and plane shear strength. The results indicated that the interlayer behaved in an elastic manner at lower temperatures, generating brittle failures with cracking, whereas viscoelastic behavior dominated at higher temperatures, producing ductile failure that led to slippage at the interface layer. The surface texture effects can be quantitatively characterized using the clamping shear strength. In addition, the clamping shear strength can be used to optimize the asphalt mixture to enhance the bonding performance. Key words: asphalt concrete (AC) overlay, interlayer bonding failure, clamping strength, texture, Portland cement concrete (PCC) rehabilitation. La fissuration parabolique de glissement des couches d'asphalte se produit a la suite d'une defaillance de l'adherence entre les couches de beton asphaltique (BA) et le beton de ciment Portland (BCP). Un essai de cisaillement direct a ete adopte pour simuler la defaillance d'adherence commune et critique. Les effets de la temperature et de la couche d'adherence ont deja ete etudies par des chercheurs precedents, mais les effets de la texture n'ont pas ete suffisamment pris en compte. Cette etude a utilise la resistance au cisaillement de serrage pour caracteriser la resistance au cisaillement pure dans la chaussee. Elle est definie comme la difference entre la resistance totale au cisaillement et la resistance au cisaillement normale. Les resultats ont montre que l'inter couche s'est comportee de maniere elastique a des temperatures plus basses, generant des ruptures fragiles avec fissuration, tandis que le comportement viscoelastique a domine a des temperatures plus elevees, produisant une rupture ductile qui conduit au glissement a la couche d'interface. Les effets de texture de surface peuvent etre caracterises quantitativement en utilisant la resistance au cisaillement de serrage, et cette resistance peut etre utilisee pour optimiser le melange d'asphalte dans l'amelioration des performances de l'adherence. [Traduit par la Redaction] Mots-cles : rechargement de beton asphaltique (BA), defaillance de l'adherence entre les couches, force de serrage, texture, readaptation du beton de ciment Portland (BCP)., Introduction Asphalt concrete (AC) overlay is one of the most typical pavement maintenance strategies used in Portland cement concrete (PCC) pavements to extend their service life. The life of an [...]

Reflection cracking is a critical issue in asphalt overlay pavement. Temperature variation and traffic loading are the main fracture modes acting on the material. In this paper, a multi-modal overlay tester is proposed for the evaluation of the reflection cracking resistance of an asphalt mixture, an approach that simulates three loading modes on asphalt specimens. A fine dense-grade hot mix asphalt is used as the test specimen and subjected to different loading conditions such as single Mode I, II, and III loading simulations and combined I+II and I+II+III loading simulations. Results show coefficients of variation (CVs) of 2.5%, 10.3%, and 7.4% for the Mode I, II, and III loading simulations, respectively. Furthermore, the [beta] coefficient, with a CVof 7%, is used to represent the crack resistance of the asphalt mixture. Finally, the crack propagation occurs rapidly when subjected to tension and lateral displacement prior to repeated traffic loading simulations. Key words: fatigue test, mixed loading mode, reflection cracking, asphalt overlay tester. La fissuration par reflexion est un probleme critique pour les chaussees asphaltees. La variation de temperature et la charge de roulage sont les principaux modes de rupture agissant sur le materiau. Dans le present document, un appareil d'essai de revetement multimodal est propose pour l'evaluation de la resistance a la fissuration par reflexion d'un melange d'asphalte, une approche qui simule trois modes de chargement sur des echantillons d'asphalte. Un asphalte melange a chaud a base d'agregat a haute densite est utilise comme echantillon d'essai et soumis a differentes conditions de chargement, comme des simulations de chargement en mode I, II et III simples et des simulations de chargement combinees I+II et I+II+III. Les resultats montrent des coefficients de variation (CV) de 2,5, 10,3 et 7,4 % pour les simulations de chargement des modes I, II et III, respectivement. De plus, le coefficient [beta], avec un CV de 7 %, est utilise pour representer la resistance a la fissuration du melange d'asphalte. Enfin, la propagation des fissures se produit rapidement lorsqu'elles sont soumises a une traction et a un deplacement lateral avant les simulations repetees de charges de roulage. [Traduit par la Redaction] Mots-cles : essai de fatigue, mode de chargement mixte, fissuration par reflexion, appareil d'essai de revetement bitumineux., Introduction Reflection cracking is a major problem that needs to be overcome in asphalt overlays on Portland cement concrete (PCC) pavement. Accordingly, the design of an asphalt overlay requires accurate [...]

Permeable pavement is widely used to improve the water circulation system in urban areas. The advantages of using permeable pavement are the storage of rainwater, reduction of runoff, out-flow delay, and reduction of peak discharge. The outflow characteristics of different types of permeable pavements are explained by runoff coefficients, which define the relationship between runoff and infiltration rate. This study presents a model of cumulative outflow with respect to time explaining the discharge characteristics of permeable pavement. The model can be used to explain storage capacity, delay time, peak discharge rate, and outflow of pavement structure by accumulating total discharge at the surface and subsurface relative to time. For further verification of the model, a rainfall simulation experiment was performed in the field. Based on the data analysis through the developed model, the advantages of different permeable pavements can be characterized. Key words: permeable pavement, pavement storage capacity, cumulative water flow, time and space model. Les chaussees permeables sont utilisees pour ameliorer le systeme de circulation d'eau dans les zones urbaines. Elles presentent les avantages suivants : l'entreposage de l'eau de pluie, la reduction du ruissellement, le delai des ecoulements et la reduction du debit de pointe. Les caracteristiques des rejets pour divers types de chaussees permeables sont expliquees en tant que coefficient de ruissellement, lequel definit la relation entre le ruissellement et le taux d'infiltration. Cette etude presente un modele de rejet cumulatif qui tient compte du temps, expliquant les caracteristiques de decharge des chaussees permeables. Le modele peut servir a expliquer la capacite d'entreposage, le delai, le debit de pointe et le rejet par la chaussee en accumulant, dans le temps, la decharge totale a la surface et dans la sous-surface. Pour pousser la verification du modele, une experience de simulation de precipitations a ete realisee sur le terrain. En se basant sur l'analyse des donnees par le modele mis au point, il est possible de caracteriser les avantages des diverses chaussees permeables. [Traduit par la Redaction] Mots-cles: chaussee permeable, capacite d'entreposage des chaussees, debit d'eau cumulatif, modele de temps et d'espace., 1. Introduction As urbanization continues, the convenience of the living environment has improved with efficient land utilization. The water circulation system of the city changes as ground coverage increases. The [...]

The primary objective of the present study is to assess the use of the maturity method to determine the joint sawing window and the traffic opening time on whitetopping construction in Korea. To determine the joint sawing time, it is necessary to determine the minimum strength not to have raveling and to identify the safe time of drying shrinkage. The present study found that the minimum compressive strength for joint sawing was 4.41 MPa (45 kg/[cm.sup.2]) and drying shrinkage occurred just after the concrete temperature peaked. The Nurse-Saul function was used for determining the joint sawing window and the traffic opening time because it better predicted in-place strength. The present study determined that the joint sawing window ranged from 210°C x h to 310°C x h (actual time of 6.5 to 9 h) and that the traffic opening time was after maturity values reached 390°C x h for the mix at 20°C. Key words: maturity, Nurse-Saul function, Arrhenius equation, whitetopping. Le principal objectif de la presente etude est d'examiner l'utilisation de la methode d'evaluation de la maturite afin de determiner la fenetre de coupage du joint a la scie et le moment d'ouverture a la circulation apres un resurfacage sur asphalte en Coree. Pour definir le moment de coupage du joint a la scie, il faut determiner la resistance minimale de maniere a ne pas provoquer d'arrachement et a identifier le temps adequat de retrait de sechage. La presente etude a decouvert que la resistance en compression minimale pour la coupe du joint a la scie etait de 4,41 MPa (45 kg/[cm.sup.2]) alors que le retrait de sechage est survenu une fois que le beton avait atteint sa temperature maximale. La fonction Nurse-Saul a ete utilisee pour determiner la fenetre de coupage du joint a la scie et le moment d'ouverture a la circulation parce qu'elle predisait mieux la resistance en place. Cette etude a determine que la fenetre de coupage du joint a la scie etait de 210°C-heure a 310 °C-heure (temps reel de 6,5 a 9 heures) et le moment d'ouverture a la circulation se produisait une fois que les valeurs a maturite avaient atteint 390 °C-heure pour le melange a 20°C. Mots-cles : maturite, fonction Nurse-Saul, equation d'Arrhenius, resurfacage sur asphalte. [Traduit par la Redaction], Introduction The maturity method was first applied to whitetopping construction in Korea. Because there were no reported cases of the application of maturity methods to whitetopping construction, a laboratory test [...]

The objective of this research is to evaluate how the physical properties and thickness of asphalt pavements influence behaviors of ultra thin whitetopping (UTW). The results of the three-dimensional finite-element method reveal that properties of asphalt and concrete layers, bonding between the two layers, and temperature strongly affect the distress of UTW. Based on results of FEM analysis, a wheel tracking device called the 'heart wheel load simulator (HWLS)' was developed and used to perform an experiment to observe behavior variation in accordance with asphalt and concrete layer thicknesses as well as temperature. The results of HWLS simulation show that the effect of temperature is not significant and the increase of the tensile strain with the increase of a load is relatively small for a 100 mm concrete layer, as compared to a 50 mm concrete layer. In addition, for a 50 mm concrete layer with a less than 150 mm asphalt layer, the increased ratio of the tensile strain at the bottom of the concrete slab is significantly higher. Therefore, this research recommends that an at least 150 mm asphalt layer after milling be required in order to apply UTW safely. DOI: 10.1061/(ASCE)0733-947X(2006) (880) CE Database subject headings: Rehabilitation; Asphalt pavements; Simulation.

Byline: Do Hyun Ahn, Jae Kyeong Kim, Il Young Choi, Yoon Ho Cho With the advance of e-commerce, the importance of recommender systems grows larger than before. Collaborative filtering is the most successful recommendation method, but its widespread use has exposed some problems such as sparsity and scalability. To overcome such limitations, this paper proposes hybrid recommendation methodologies based on web usage mining and dimensionality reduction techniques to enhance the recommendation quality and performance of current collaborative filtering-based recommender systems. Web usage mining populates the rating database by tracking customers' shopping behaviours on the web, thereby leading to better quality recommendations. The product taxonomy and SVD (Singular Value Decomposition) are used to improve the performance of searching for nearest neighbours through dimensionality reduction of the rating database. Experiments on real e-commerce data show that the proposed methodologies provide higher quality recommendations and better performance than existing collaborative filtering methodologies.