Search

The aim of this research is to define a breakage limit for the fastening system of the "Eurobalise" device of the ERTMS/ETCS rail signalling system on the European railways. The widespread presence of the system along the European railway line and the increasing of high-speed lines have led the research to find design solutions able to increase the attack system strength, avoiding its detachment from the sleepers. Mechanical tests on tensile, shear and bending configurations have been carried out to evaluate the jointing systems between Eurobalise and sleepers. Additional full-scale tests allowed the definition of the load actions and of the breaking points. The connection between balise and sleepers is able to react to the train’s aerodynamic actions, confirming the system reliability even for the passage of high-speed trains. Through the experimental approach were defined standard test procedures useful to improve the sheet data of this kind of fastening system.

Road markings visibility is usually assessed by means of the visibility level (VL). Several models have been developed to calculate the visibility distance on the road (Detect/PCDetect, Carve/Tarvip, Cost 331 and CIE 73). These models all approximate the visibility of a marking by estimating the diameter of an ‘equivalent’ disc. In this process, speculative hypotheses are made to calculate this diameter, labelled the equivalent area hypothesis, the equivalent perimeter hypothesis or the equivalent width hypothesis. To compare these hypotheses, a psychophysical experiment was conducted with eight participants and 120 stimuli. It was found that the merit of each hypothesis changed with the diameter of the equivalent disc. Above 0·1°, all the hypotheses gave good results, but the equivalent area hypothesis was found to be the best. Below 0·1°, the equivalent width hypothesis was more accurate, but further investigations are still needed.

Today the use of Construction and Demolition Materials (CDM) can be considered as a suitable solution for the construction or the rehabilitation of road pavements. In this context, it is central to minimizing waste production, favoring the reuse through new production cycles to replace virgin natural raw materials. As illustrated in this study, steel slag has mechanical properties that justify its use as aggregate in the manufacture of bituminous mixes. In road construction, their use is focused on the substitution of fine aggregate and filler in bituminous mixtures. Mechanical characterizations, Marshall stability and indirect tensile resilient modulus (ITSM) tests were used to evaluate the laboratory performance of the mixtures. The research aims are to provide the use of these materials for the construction of the entire road pavement structure, in this study authors used these materials both in the characterization of cementitious layers and in those with bituminous conglomerate. In both cases, the use of steel slag has favored an increase of stiffness in the mixtures.

Mineral fillers have a key role in controlling the mechanical characteristics of asphalt concretes (AC). The cohesion properties of bituminous mastics depend upon the fillers used, and, therefore, so do the effective strength of asphalt concretes and the durability of the pavement layers. Recent research has studied the using of waste bleaching clays from the food industry as a substitute of common limestone filler traditionally used in the production of ACs for binder layers. In this paper, a waste bleaching clay is proposed as alternative filler for the production of a porous asphalt (PA) mixture. The waste filler (Ud) comes from two consecutive stages in the industrial process for decolouring vegetable oils and producing biogas from bleaching clays. The aim of this research was to assess the performance of the PA, in terms of physical and mechanical characteristics, when compared to traditional PA. Thus, two porous asphalt mixtures with the same dosages of binder and aggregates gradation were studied in the laboratory: one with traditional limestone filler and one with waste bleaching clay. Tests results are promising in terms of increasing of Indirect Tensile Strength, stiffness, and resistance to permanent deformations.

In this paper a green waterproofing membrane for the protection of concrete decks is proposed. It is composed of a recycled rubber mat, sandwiched between two layers of SBS-modified bitumen. The rubber mat, itself, provides advantages in terms of environmental impact, because it is composed by a high density elastic mat made with granular rubber coming from the recycling of End of Life Tires, stuck with isocyanate and pressed. The polymer modified bitumen improves the interfaces adhesion and bonding, providing to the system a good water resistance. The rubber mat, different from the most common waterproofing membranes, is not supplied in rolls but can be applied in layers directly in work, according to the area to be covered. Laboratory characterization and a comparison to manufacturer's limiting values and tolerances of other available membranes confirm the overall performance and the use conformity of the proposed system.

New technologies are changing the sector of infrastructures design and construction. One of the most important is the I-BIM (Infrastructure Building Information Modelling), that is a management information system of digital processes for infrastructures. In this study the I-BIM approach has been used for the upgrade of a section of the SS 245 road, in the north of Italy, in order to show its benefits applied on existing road infrastructure. The project involved the design of a new road segment and its connection with the existing road network and with a railway line. These last were respectively solved by a roundabout and by a jacked tunnel under the railroad with wing walls at each exit side of the structure. The steps carried out in this study were modelling the 3D digital terrain model from point cloud; creating the horizontal alignment, vertical profiles and editing cross-sections; modelling the jacked tunnel; creating the roundabout; generating the 3D parametric model of the complete road and visualizing the infrastructure in the real-world context. The real innovation consists in the creation of a plugin that allows extrapolating directly from the design program to the compute one, all the features need to be calculated. The BIM tools used were “Autodesk AutoCAD Civil 3D” and “Revit Structure”, used respectively for road geometrical design and for tunnel structural project. The obtained results have been showed that the I-BIM approach represents not only a powerful tool to optimize and validate the road project according to norms before its construction, but also to see how the infrastructure works with the 3D real environmental context.

Besides the many advantages of porous asphalt (PA), the permanent deformation resistance, fatigue strength, stripping and moisture susceptibility are not as good as for dense graded mixtures. In this research, the effectiveness of adding crumb rubber (CR) by dry method to PA mixtures was assessed. Rubberized porous asphalt (RPA) mixtures manufactured incorporating CR into SBS modified asphalt concrete were produced and compared with a control mixture by means of Indirect Tensile Strength (ITS), Indirect Tensile Stiffness Modulus (ITSM), moisture susceptibility, permeability, Cantabro, rolling bottle, draindown and creep tests. Results proved that although the application of CR reduces the vertical permeability and permanent deformation resistance, it improves the bitumen/aggregate affinity and it controls the draindown rate without adding fibres. On the other hand, the use of CR decreased the ITSM value at low temperature, which represents a lower susceptibility to thermal cracking. Other complementary test results in this research support the effectiveness of RPA mixtures.

The adhesion between bitumen and aggregates is of paramount importance for asphalt mixtures, because it is confirmed that a weak bond strength results in a premature failure of the pavement. Methods for determining the affinity or the adhesion between components are made both on loose and compacted samples. Among the first category the rolling bottle method, which is standardized in EN 12697-11 part a, is very common. It represents a simple, rapid and low cost test for an indication of the affinity between aggregate and bitumen and its influence on the susceptibility of the mixture to stripping. This paper proposes the use of 2D image analysis to evaluate the rolling bottle test results, overcoming the limits and shortcomings of the visual analysis prescribed by the reference standard. In order to demonstrate its applicability to a broad range of materials, this procedure was applied to both light and dark aggregates, mixed with a wax modified binder. The mixing temperature was varied so that the influence of the binder viscosity on the adhesion was assessed. A comparison between visual and semi-automatic estimation is presented, demonstrating that the latter brings to far better results. The accuracies were determined through confusion matrixes that permit to identify the errors made during the process of classification.

The increasing traffic rate experienced by regional airports in Europe in recent years has had various impacts on the communities living near to the airport areas. To mitigate the negative effects of aviation noise, airports, particularly those close to dwellings and communities, have developed a number of noise abatement measures, of which the noise abatement procedures are one of the most widely adopted. Guglielmo Marconi International Airport, in Italy, is a prototypal case of an urban regional airport, which will probably be seriously constrained by environmental factors in the short–medium term, because of its proximity to the suburbs of the city of Bologna and the growth in air traffic in the last decade. This has encouraged the airport management to take appropriate countermeasures to promote awareness among carriers, encouraging them to limit, as far as possible, their departure operations over inhabited areas during certain time windows. This has led to the formulation of a new initial climb procedure for take-offs from runway 12. In this paper, the effectiveness of this procedure is evaluated by carrying out a before–after analysis of noise curves and percentage of population and sensitive buildings within the noise contours.

In recent years, the use of crumb rubber as modifier or additive within asphalt concretes has allowed obtaining mixtures able to bind high performances to recovery and reuse of discarded tires. To date, the common technologies that permit the reuse of rubber powder are the wet and dry ones. In this paper, a dry-hybrid technology for the production of Stone Mastic Asphalt mixtures is proposed. It allows the use of the rubber powder as filler, replacing part of the limestone one. Fillers are added and mixed with a high workability bitumen, modified with SBS (styrene-butadiene-styrene) polymer and paraffinic wax. The role of rubber powder and limestone filler within the bituminous mastic has been investigated through two different approaches. The first one is a rheological approach, which comprises a macro-scale laboratory analysis and a micro-scale DEM simulation. The second, instead, is a performance approach at high temperatures, which includes Multiple Stress Creep Recovery tests. The obtained results show that the rubber works as filler and it improves rheological characteristics of the polymer modified bitumen. In particular, it increases stiffness and elasticity at high temperatures and it reduces complex modulus at low temperatures. © 2016 by the authors.

Bitumen undergoes ageing, which leads to changes in its chemical and rheological properties, causing it to become harder and more brittle with time. This study aims to compare the effects of different laboratory ageing methods on the chemistry and rheology of three bitumen types: a Pen 40=60, a Pen 70=100, and a polymer-modified bitumen (PmB). Four ageing protocols were applied: ageing at room temperature, oven ageing, pressure ageing vessel (PAV), and rolling thin-film oven test (RTFOT) combined with PAVageing. The effects of temperature, pressure, and ageing time were studied using dynamic shear tests and infrared spectroscopy. The results highlight the relationship between chemistry and rheology of bitumen. Bitumen hardening, which was revealed by an increase in complex modulus and a decrease in phase angle, was reflected in the growth of specific chemical functional groups. Among all materials, soft bitumen showed the greater tendency to oxidize. Different behavior was observed for PmB, which presented the highest resistance against oxidation among the studied bitumens, even though the reaction with oxygen caused the deterioration of the added polymer modifiers.

Today the use of recycled and second-hand materials can be considered as a suitable solution for the construction or the rehabilitation of road pavements. The increasing interest in this process lead to the study and the evaluation of different waste materials, not directly connected to the construction field, among these Crumb Rubber from end-of-life tires. To date, this recycled material has been added into bituminous mixes for road pavements according to several technologies, for the production of different mixtures. In the present paper, the crumb rubber was used for the production of Stone Mastic Asphalt (SMA) according to a new dry-hybrid technology. A full laboratory investigation and a trial field study are here presented. A complete physical and mechanical characterization was carried out to define a specific mix design. Once defined these properties, a full-scale test section was constructed: specific in situ tests and collection of samples were planned. In both the laboratory and trial field phases, tests results were always compared to those obtained with a traditional SMA mixture. In an environmental prospective, fumes and emissions during laying were also analyzed. The goal of this research project was to analyze and evaluate the different physical, mechanical and functional characteristics induced by the use of Crumb Rubber for the production of SMA mixtures according to the proposed new dry-hybrid technology. As overall result, the presence of Crumb Rubber does not seem to negatively affect the volumetric properties of the mixture. SMA1.20 shows mechanical properties comparable to the reference mixture and higher if compared to SMA0.75. As for the acoustic properties, both the rubberized surfaces reduce the emission of noise if compared to the traditional SMA layer. The monitoring of pollutants during paving operations confirms the effective environmental benefits deriving from the use of the new dry-hybrid technology here proposed.

Undoubtedly, the most commonly used method for road maintenance includes the use of winter service vehicles to clear thoroughfares of snow and the spraying of chemicals to prevent ice formation on the road surface. The application of these traditional methods on road and airport pavements possesses numerous environmental, organizational, and technical challenges. To overcome these critical issues, new nontraditional technologies that act within the pavement, thereby increasing its temperature, have been developed. In relation to the heat source used, these are classified into chemical and physical methods. The purpose of this research is to study the temperature variation under the thermal transient process produced by the action of the physically heating device installed in the road pavement. The heating device is a ribbon, made of amorphous material, which is able to produce heat to warm up the pavement and its surface. Based on its principle of operation, it is classified among the nontraditional physical methods for the treatment of snow and ice. In this work, the performance of the heating ribbons on an experimental site at the G. Marconi International Airport in Bologna (Italy) is presented.

This paper summarizes a laboratory investigation into the wear of Stone Mastic Asphalt road surfacing material. Review of harmonized European test methods found no specific Wear Test and this is an important knowledge gap relating to laboratory prediction. The UK Wear Test using the Road Test Machine was applied to assess Stone Mastic Asphalt test specimens. This uses full size pneumatic tires to wear asphalt test specimens, under slow speed high stress conditions. This found 14 mm and 10 mm SMA to behave in similar ways. Relationships between variables for newly compacted test specimens quickly change with the onset of simulated trafficking. This raises issues with laboratory investigations that do not involve some aspect of tire/test specimen wear at their interface. Contact area is a better property to measure than macrotexture. Poor relationships between contact area and pendulum tester suggest that either something additional at the contact interface has to be measured or there are limitations with the pendulum tester. More research is required to better understand wear at the tire–asphalt interface and the prediction/measurement/monitoring/modeling of properties such as skid resistance, rolling resistance and noise generation.

Asphalt concrete (AC) recycling is probably the most cost-effective technique for the rehabilitation of stressed road pavements and for the construction of new ones. The increased interest in this technology comes from the need of reducing the costs connected to the production processes and to the use of virgin raw materials. In fact, the benefits connected to the use of Reclaimed Asphalt Pavement (RAP) are related to the possibility of substituting the natural aggregates and the virgin binder of an AC mixture, without negatively affecting its mechanical properties. When this process is made at ambient temperature (Cold Recycled Mixes – CRM), more advantages are brought about with, above all, the reduction in energy consumption and emissions during in plant production and laying, in addition to the actual possibility of achieving durable pavement layers. A CRM totally made of RAP is proposed in this research, the main goal of which was to evaluate the different physical and mechanical characteristics derived by the large use of recycled materials. According to the final mix-design, CRM does not show significant differences in terms of physical properties, when compared to a Hot Mix Asphalt (HMA) for base layers. Moreover, even if the experimental mixture shows lower mechanical values, these are acceptable and higher than the limits imposed by the most common Italian technical specifications for Cold Mix Asphalts containing up to 30% RAP.

Asphalt concrete mixtures are composed of two main components: aggregates and binder. The fraction of aggregates passing through the 63μm sieve is traditionally considered as filler. During years, several researches have shown the importance and the influence of filler in controlling the physical and mechanical properties of Hot Mix Asphalts (HMAs). The main objective of this research is to investigate and to assess the effects given by the use of Mining Waste Powder (MWP) within HMAs in total substitution of traditional limestone filler. The MWP used in this study is a residual of the tungsten extraction process in Panasqueira (Portugal) mine. The evaluation of properties conferred by the presence of the MWP filler within asphalt mixtures is based on a physical and mechanical laboratory characterization. For this purpose, tests have been performed both on bituminous mastics and on HMAs. Results indicate that the use of MWP in total substitution of limestone filler does not negatively affect the performances of HMAs and their bituminous mastics.

This work is based on the characterization of road materials that combine high performance and reduction of the environmental impact during road construction and maintenance. In particular polymer modified bitumens with and without wax additives have been studied. The first increase the elasto-plasticity of the mixture, increasing its durability and fatigue resistance. As for the second the presence of paraffinic additive reduces the bitumen viscosity and consequently the asphalt mixing and compaction temperatures. A number of studies have shown that the mechanical characteristics of pavement are strongly influenced by the oxidation degree of the organic components of the bitumen during mixing and compaction phases. This phenomenon is known as short-term aging. Binders modified with polymer and wax were analyzed according to the viscoelasticity theory and different aging conditions were simulated. Tests of advanced rheological characterization were carried out by using the Dynamic Shear Rheometer and the short-term aging was simulated by Rolling Thin Film Oven Test. A new procedure of bitumen aging at the equiviscous temperature or T mixing was proposed. Further rheological tests on aged binders were carried out at this temperature. The results have been supported by FTIR (Fourier Transform Infrared Spectroscopy) analytical chemical tests, analyzing the molecular changes on the aged binders. The standard temperature of 163 °C does not correctly simulate the short term aging of polymer modified and waxes bitumens.

Driving simulators have been becoming little by little a suitable tool oriented to improve the knowledge about the domain of driving research. The investigations that can be conducted with this type of tool concern the driver’s behaviour, the design/control of vehicles, testing assistance systems for driving and the roadway infrastructure’s impact. The benefits of simulation studies are many: lack of any real risk to users, reproducible situations, time savings and reduced testing costs. In addition, their flexibility allows to test situations that do not exist in reality or at least they rarely and randomly exist. The topic of the present work concerns the development of a brand new dynamic model for an existing car simulator owned by LEPSIS laboratory (Laboratoire d’Expliotation, Perception, Simulateurs et Silulations – Laboratory for Road Operations, Perception, Simulators and Simulations) belonging to COSYS (COmposants et SYStems), which is a department of IFSTTAR institute (Institut Français des Sciences et Technologies des Transports, de l’Aménagement et des Réseaux – French Institute of Science and Technology for Transport, Spatial Planning, Development and Networks) site. Once uses and advantages of driving simulators are listed and described, imperfections and limitations of the existing driving vehicle model belonging to the two Degrees of Freedom (DoF) driving simulator of the laboratory are highlighted. Subsequently, structure of the brand new vehicle model, designed by means of Matlab Simulink software, are illustrated through the theoretical framework. Since the vehicle model must refer to a real one, an instrumented Peugeot 406 has been chosen because all its technical features are provided and inserted both on the present model and Prosper/Callas 4.9 by OKTAL software to create a highly sophisticated and accurate virtual version of the commercial car. The validation of this new vehicle model is performed, where the results returned by several different driving scenarios are compared with the ones provided by Prosper software. All the scenarios are simulated with both existing and new vehicle model uploaded in the driving simulator, and the outputs are subsequently compared with the ones returned by Prosper in order to demonstrate the improvements done. Finally, being the number of outputs provided by the new model definitively higher with respect to previous one, additional validations concerning the further results are accomplished.

Bleaching clays are mostly used in food industries to clarify vegetal oils. After use they are generally dumped as waste (stage 1) or used in green innovative plants to feed biogas reactors (stage 2). In latter stage the initial residual oil content (approx. 25 % by mass) is reduced to less than 1 % by the biological process. In this study the bleaching clays effects on bituminous mastics of a traditional binder course Hot Mix Asphalt have been investigated. The physical characteristics of the two bleaching clays and of a traditional limestone filler were also studied. DSR rheological tests at high and low temperatures were performed on mastics samples containing different amounts of fillers (limestone, stage 1 or stage 2). The addition of the different waste bleaching clays significantly affects the rheological behavior of the mastics: the filler from stage 2 increases the mastic stiffness improving the resistance to permanent deformations as shown by repeated creep tests, while the filler from stage 1 strongly interacts with the bitumen reducing the mechanical characteristics of the mastics at all temperatures.

The infrastructure system has experienced an unprecedented development in the last fifty years. Most of the road pavements have been used for over twenty years and today require increasing maintenance to keep acceptable their levels of performance. In addition, the use of virgin and raw materials has been strongly restricted by raising price and eco-friendly policies. As a result, researchers and companies have focused their attention on recycling techniques with waste and second-hand materials that could lead to the construction and restoration of civil infrastructures without negatively affecting their mechanical properties. The study presented in this paper pursues this trend of research, by the evaluation of the performance of two different 100% Recycled Cement Bound Mixture (RCBM) for base layers. Data were always compared to those obtained for a traditional Cement Bound Mixtures (CBM) entirely made of virgin aggregates. The experimental programme was divided into two different and consecutive phases: a laboratory study and a trial field phase. In the first, the aim was the mix design and the physical and mechanical characterization of three mixtures. In the second phase, a full-scale trial field was realized: in situ tests and sampling were planned in four dates, corresponding to 0, 60, 180 and 365 days of trafficking. Based on results, the replacement of virgin aggregates with waste materials in CBMs, according to these specific mix designs seems to be a practicable solution for the construction of base layers with suitable performance.

This paper presents laboratory study results, including both bituminous mastics and mixtures tests, to assess the use of glass powder (GP) as possible surrogate to limestone filler in recycled dense-graded asphalt mixtures. To achieve a comprehensive approach, the analysis has been divided into three parts including filler, mastics and mixture characterisation. The GP has been completely studied with chemical and physical tests to compare the fundamental characteristics to the commonly used limestone filler. In the second part, rheological tests using the Dynamic Shear Rheometer has been implemented to evaluate fillers interaction with not modified and modified bitumen. Finally, the mechanical properties of the asphalt mixtures containing GP filler were investigated in terms of indirect tensile strength, indirect tensile stiffness modulus and creep characteristics. According to the obtained results, GP filler provided comparable values to limestone filler within both mastic and mixture study. It is noteworthy that from the permanent deformation analysis, both MSCR and RLAT tests confirmed the improvement of rutting resistance with using GP filler.

There has been a significant increase in the demand for using recycled materials in construction because of the lack and limitation of available natural resources. A number of industrial and domestic waste products are being used in the replacement of traditional materials for road construction, and many studies have been carried out in recent years on the use of different recycled materials in substitution of conventional fillers in Asphalt Concretes (AC). The aim of this laboratory research is to analyze the physical characteristics of three different recycled fillers and compare them with those of a traditional limestone filler. The alternative fillers presented in this paper are: a waste bleaching clay that comes from two consecutive stages in the industrial process for decolouring vegetable oils and producing biogas (Ud filler), a dried mud waste from a tungsten mine (MW filler) and a recycled glass powder (Gl filler). Results show significant differences between the fillers, and, in particular, Rigden Voids (RV) seem to have the largest potential influence on the rheology of ACs.