[Numberless Heading] Abstract[Normal] Manuscript preparation for CETRA 2014 proceedings is a fairly simplified process. Everything you need for a properly formatted article is contained in this template document which uses a feature of Microsoft Word called Styles. A style is a set of formatting characteristics that you can apply to text in your document to quickly change its appearance. When you apply a style, you apply a whole group of formats in one simple step. For example, you may want to format the sections headers to make them stand out. Instead of changing the headings one by one, you can give them a style and change them all at once. All the styles in this document are preformatted so you only need to pick an appropriate one for the part you are working on. In this example document each section that uses a specific style starts with a style name surrounded by square brackets for easy identification. The text you are reading at the moment is formatted using [Normal] style, whilst the heading above it uses [Numberless Heading] style and so on. These words serve only as a reference and should be omitted in the paper you submit. Figure 2. This group may be expanded to a list by clicking on the icon in its lower-right corner which will open a window similar to the one in Figure 3.
The judicious pavement design is the key factor in achieving the longest service life and the lowest maintenance and rehabilitation costs. It is based on the consideration of the phenomena in which the pavement structures are subjected to exploitation and the limitation of their destructive effects.The aim of this study is to verify the possibility of implementing in the flexible pavement structures design practice of another design criterion based on limiting the bituminous mixtures creep phenomenon and that to be called: The criterion of admissible octahedral shear stresses in the bituminous layers.Estimation of octahedral shear stresses is done with a calculation model based on finite element method, and hereafter referred to as 2D ASFEM (2D Axi-Symmetric Finite Element Model). The paper presents the results obtained by modeling several specific calculation assumptions for the behaviour of flexible pavement structures in service.The study underlines the fact that the Octahedral Shear Stresses Ratio (OSSR) can be an additional design criterion to be taken into account when designing flexible pavement structures alongside other established criteria. Keywords: flexible pavement structures, octahedral shear stresses, permanent deformation RésuméLa conception judicieuse des structures de chaussée est le facteur clé pour atteindre la durée de vie la plus longue et les coûts d'entretien et de réhabilitation les plus bas. Il est basé sur la prise en compte des phénomènes dans lesquels les structures de chaussée sont soumises à l'exploitation et la limitation de leurs effets destructeurs.Le but de cette étude est de vérifier la possibilité de mettre en oeuvre dans la pratique de conception de structures de chaussées flexibles un autre critère de conception basé sur la limitation du phénomène de fluage des mélanges bitumineux: Le critère des contraintes de cisaillement octaédrique admissibles dans les couches bitumineuses.L'estimation des contraintes de cisaillement octaédriques est faite avec un modèle de L'étude souligne le fait que le Ratio de Contraintes de Cisaillement Octaédrique (RCCO) peut être un critère de conception additionnel à prendre en compte lors de la conception de structures de chaussées flexibles parallèlement à d'autres critères établis.
Asphalt mixtures are mixtures of mineral aggregates, filler, bitumen and eventually additives in proportions determined by recipe designed in the laboratory. Asphalt mixtures used as base course are bituminous concrete. The natural aggregates are granular materials of mineral origin that come from natural or artificial crushing of the rocks. In our country there are the various rocks: eruptive or magmatic rocks, metamorphic rocks, sedimentary rocks. To the category of sedimentary rocks belong limestone. Sedimentary rocks are characterized by relatively high porosity and a pronounced stratification, which causes mechanical resistance to be low and vary by direction of load. Due to the structure less dense and weaker mechanical resistance, the limestone are used less in heavy traffic pavement structures. This paper presents an asphalt mixture recipe for the base layer developed in the Laboratory of Roads from Technical University of Civil Engineering Bucharest (TUCEB), using limestone aggregates extracted from Hoghiz Quarry. The paper contains laboratory test results to determine the recipe and laboratory findings leading to the schedule of product.
As a result of the economic crisis of 2009-2010, the road traffic on the national road network, for the period 2011-2014, decreased considerably. Thus, the evolution coefficients, for the period 2020-2025, registered a trend of decrease in road traffic. Based on the analysis of the results of the automatic traffic records, it was found that the average daily average traffic increased by about 4.7% in 2016 compared to 2015 (the year of the last general circulation census) and is in continuous growth, one of the reasons being removal of car registration tax. In 2015, for the development of evolution coefficients and the rates of evolution of traffic on the national road network, the linear regression method was used which took into account both the evolution of road traffic reported in 1995, 2000, 2005 and 2010, as well as the evolution of road traffic on the traffic counters network for the period 2010-2015. The paper analyzes aspects of the efficiency of the method used until the present and the need to develop coefficients and rates of evolution based on more complex methods, based on several economic and social indicators, including the projected evolution of GDP.
“Warm Mix Asphalt” (WMA) is a technology developed to obtain an asphalt mixture at lower temperatures. The method has significant benefits for the economic and environmental area. As known, “warm mix asphalt” uses additives in bitumen having the purpose to reduce the viscosity in order to decrease the mixing and compaction temperatures. Hot mix asphalt used in the airport area, especially the area of taxiway and the apron must satisfy beside usual requirements for roads, some requirements related to fuel resistance and de-icing agents according to European norms. Does warm mix asphalt for airport use meet the requirements according to European norms? This is the question from this paper which aims to determine the characteristics of asphalt mixtures for airports BBA16 when using or not using an additive, considering a series of laboratory tests: cyclic triaxial compression test, fatigue test, stiffness modulus test and resistances to fuels test.
Asphalt mixtures are being used in road construction more and more, to the deficit of concrete surfaces. Due to the additives as well as the new technologies being used to obtain asphalt mixtures, the results are vastly improved which can lead to a better behavior in day to day situations, even under heavy traffic. This study means to show the way in which changing the binder influences the properties of the mixture. So, the chosen binder course, type BAD 22.4, will use different types of binder (bitumen), more specifically: a 50/70pen bitumen; a 50/70pen bitumen modified with flexible semi-rigid polymers and a PmB 45/80-65 bitumen, modified with polymers by crosslinking. The asphalt mixtures will be characterized by their volumetric properties, Marshall Characteristics and their behavior to dynamic tests. The results presented in the form of charts and tables were obtained in the Road Laboratory of the Technical University of Civil Engineering of Bucharest. The conclusion that can be drawn is that depending on the type of binder used, the results obtained differ with a noted improvement of the resistance to permanent deformation and creep, in the mix which uses the binder modified with polymers by crosslinking technology.
Under the current conditions of road traffic growth, importance should be given to the use of construction products whose technical characteristics have to be tested and to comply with the regulations in force. In our country at present there is the European standard EN 13043:2003 regarding the conditions that natural and artificial aggregates must meet in order to be used in asphalt mixtures. As is well known, these conditions are presented in the form of categories of values to be set by the designer to result in an asphalt mix with certain characteristics. However, this standard does not contain a national annex with specifications on the aggregate categories depending on the type of asphalt mix correlated with the technical class / road / street technical category. The majority of beneficiaries that use aggregates in the production of asphalt mixtures have problems on the national market because there is no correlation between this standard and the national provisions in force, namely the AND 605/2016 (version in force on this date). This paper analyzes the conditions that the natural aggregates for the bituminous mixtures must have and correlates the performance of the aggregates with the performance of the asphalt mix.
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