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Journées techniques "Acoustique et vibration", LILLE, FRANCE, 11-/03/2020 - 12/03/2020; Le projet européen LIFE E-VIA vise à réduire les nuisances sonores liées au trafic routier, dans la perspective future où les véhicules électriques et hybrides constituent un part significative du trafic. En conjuguant les connaissances sur les revêtements de chaussée et les pneumatiques, une solution optimisée sera testée, prenant en compte la réduction du bruit en zone urbaine et le coût de cycle de vie. Une présentation du projet est effectuée, ainsi que l'implication de l'UMRAE dans LIFE E-VIA.

The importance of heavy vehicles traffic and the composition of bituminous mixes along with their mode of implementation influence the durability and the performance of wearing courses, especially resistance to polishing and the stripping of aggregates on the surface. This traffic-texture combination can be expressed through the distribution of pressures in the tyre-coating contact zone. The study presented in this article sets out an affordable methodology to measure the local pressures distribution and the real contact area between viscoelastic rubber and a surface road. The principle consists of intercalating a Prescale Fujifilm between a tyre and the road surface in specific temperature, humidity and load conditions in static mode. Then, using the analysis of images, we use the footprint left on the Fuji paper through the mechanical contact of the two surfaces to determine the distribution of local pressures and the real contact area with high precision and a good resolution. The effect caused by variations in the inflation pressure and intensity of the load is evaluated.

National audience; La texture et la porosité sont des caractéristiques du revêtement routier déterminantes pour l'émission acoustique provoquée par le contact pneumatique/chaussée. Le modèle HyRoNE (Hybrid Rolling Noise Estimation), développé dans le cadre des projets Prédit « Texure&Bruit » et Deufrako P2RN, a pour objectif la prévision du bruit de roulement à partir de profils de texture et des propriétés d'absorption acoustique des revêtements. Le modèle est basé sur des lois statistiques utilisant, d'une part, la texture « enveloppée » (partie supérieure du profil susceptible de rentrer en contact avec la gomme du pneumatique) pour l'évaluation de la composante due au phénomène de mise en vibration et rayonnement du pneumatique, et d'autre part, la texture brute pour la détermination de la composante due au phénomène de pompage d'air. L'influence d'éventuelles propriétés d'absorption du revêtement est prise en compte en introduisant l'effet de sol entre la source et le point récepteur. Le modèle est construit sur un jeu de données de niveaux de bruit et de texture, d'absorption acoustique, mesurées sur un ensemble de revêtements. L'introduction, dans ce jeu de données, d'un revêtement lisse permet de mettre en évidence et de prendre en compte dans les lois statistiques des contributions sonores indépendantes du revêtement.

The improvement of skid resistance of pavements requires some means of characterization of the surface condition on the aggregate scale (macrotexture) and of their polish (microtexture). However, to date, the microtexture, more particularly height variations from one up to about ten micrometers in amplitude, cannot be correctly apprehended by means implemented in civil engineering (owing to the limitation of the measuring range of profilometers at the required resolution). The research works carried out come within the general framework of works of the LCPC intended to reach a better understanding of the contribution of microtexture to tire/road friction. They aim at the development of a global characterization method of microtexture by using the speckle techniques, more particularly in the case of an unresolved subjective speckle. In view of the lack of information available regarding the application of speckle techniques to multi-scale surfaces, some simulations of the speckle contrast are carried out using the scalar diffraction theory of Kirchhoff in case of a two-scale surface texture and for the selected particular experimental configuration. They demonstrate the possibility to characterize by the chosen method, the coarseness of the microtexture or any changes with wear. In the second time, the first-order statistics of speckle (contrast, histogram of intensity) are examined within the framework of experiments carried out with some reference surfaces (abrasive papers with different kinds of coarseness) and some models of pavement surfaces (various rocks, various steps of wear), all samples being calibrated by recording some profiles. By means of adapted treatments of the speckle images, we achieve to discriminate the reference surfaces and in the case of the models of pavement surfaces, two different kinds of coarseness and two different steps of wear., Afin d'améliorer l'adhérence des chaussées, il est nécessaire d'accéder à une caractérisation de leur état de surface tant à l'échelle des granulats (macrotexture) que de leur rugosité locale (microtexture). Or, à ce jour, la microtexture et plus particulièrement les aspérités d'amplitude comprise entre un et quelques dizaines de micromètres, ne peut être appréhendée de manière satisfaisante par les moyens mis en œuvre en génie civil (limitation de l'étendue de mesure des profilomètres aux résolutions souhaitées). Les travaux de recherches réalisés s'inscrivent dans le cadre plus global de travaux du LCPC destinés à accéder à une meilleure compréhension de l'apport de la microtexture au frottement pneumatique/chaussée. Ils ont pour objectif l'élaboration d'une méthode de caractérisation globale de la microtexture par l'emploi des techniques du speckle, plus particulièrement dans le cas d'un speckle subjectif non résolu. Devant le peu d'informations disponibles sur l'application des techniques du speckle aux surfaces multi-échelles, des simulations du contraste de speckle dans la configuration expérimentale particulière choisie sont réalisées pour une surface comportant deux échelles de texture à l'aide du modèle de diffraction scalaire de Kirchhoff. Celles-ci démontrent la possibilité de caractériser la finesse de la microtexture ou son évolution avec l'usure par la méthode choisie. Dans un second temps, les paramètres statistiques du premier ordre du speckle (contraste, histogramme de l'intensité) sont examinés dans le cadre d'expérimentations réalisées sur des surfaces de référence (papiers abrasifs de différente finesse) et sur des modèles de surface de chaussée (différentes roches, différents stades d'usure), chaque échantillon étant étalonné par des relevés de profils. Par des traitements adaptés des images de speckle, nous parvenons à séparer les surfaces de référence et dans le cas des modèles de chaussée, deux finesses différentes et deux stades d'usure.

The purpose of roads in areas of seasonal frost is to attenuate frost penetration and thus permit the design pavement thickness to be reduced. Early indications from actual use are that polystyrene insulation will meet these requirements. Two 100-ft (32.8-m) sections of street were constructed in Sudbury, Ontario, Canada, in September 1964 using 2-by-4-ft by 2-in. (0.610-by l.220-m by 5.08-cm) sheets of extruded polystyrene insulation in the pavement structure at a depth of 16 in. (0.406 m). In the summer of 1965 two additional insulated road sections were constructed in Ottawa, Ontario, Canada. Two types of insulation and methods were used. Extruded polystyrene boards were placed by hand (the same as at Sudbury) at the desired elevation. Polyurethane was foamed in place by spraying the chemicals on the road bed with a specially constructed self-propelled spraying machine. This paper discusses the relative merits of the different methods of roads and, in a broader context, the protection against freezing of underground utilities, such as water mains and sewers.

The results of two field studies on the performance of a novel sulphur/asphalt composite pothole repair system are described, as well as the material properties and equipment development. More than 100 potholes at each location (Ville St-Laurent, Quebec, and Winnipeg, Manitoba) were repaired under both summer and winter conditions. Control patches using conventional cold patch material were made whenever possible. Road types repaired included concrete pavement with and without asphalt overlays and asphalt pavement on a granular base. The potholes were prepared using various methods of cleaning and preheating, tack coat, wire mesh reinforcement, crushed stone filler and edge cutting. The composite system performed better, by far, than the conventional cold patch material.

Changes in the dimensions and heat content of hydrated cement specimens were determined as a function of temperature and concentration of deicing agent in cooling- warming cycles between +15 degrees C and -70 degrees C. The concentration of the polar deicer (NaCl) solution varied from 0 to 26% and that of the nonpolar (urea) solution from 0 to 40%. The w/c raios were 0.4, 0.6, and 0.8 plain and 0. 5 air-entrained. Experiments were also conducted to clarify the effect of cooling rate and sample size. The observations can be explained by the mechanism previously proposed for phase transitions of adsorbates. In the presence of salts, freezing and melting of liquid exuded from the pores on cooling proceed according to the bulk phase diagram, producing double peaks in the thermograms except at extreme concentrations. The detrimental effect of deicers is attributed mainly to the high degree of saturation, a consequence of the low vapor pressure of the solutions. A beneficial aspect is the widening of the temperature range in which transitions occur. These opposing effects result in the worst conditions at a low deicer concentration (5% NaCl) and optimum conditions at a moderately high concentration (13% NaCl). Since the effect of deicers is physical, it should be common to all chemicals. Air entrainment, although beneficial in most circumstances, can be detrimental. The best protection against "salt scaling" appears to be reduction of porosity.

The reinforced sulphur/asphalt composite repair material discussed in this paper was developed primarily for the repair of potholes in roads. 15000 pounds of repair material and 1000 pounds of reinforced sulphur/asphalt binder have been produced by a prototype blending system developed by the Ontario Research Foundation. Quality control tests were conducted on samples to assess appearance, density, stability, hardness and compressive strength. The paper describes the tests and the results.

This paper is a report of a cooperative research program carried out in 1958 and 1959 by the National Research Council, Canada, and the Ontario Department of Highways to study the performance of some existing roads over muskeg in northern Ontario. Investigation of close to 50 different muskeg areas included classification of the muskeg, determination of the depth and type of fill, depth of the organic deposit, and type of mineral soil substratum. Roads over the muskeg areas were assessed on the basis of performance and surface condition relative to adjacent sections of road on mineral soil terrain. Many peat samples were obtained for laboratory analyses, which included water content, specific gravity, acidity, and ash content. During the second stage of the project an extensive series of field vane tests was carried out in certain selected muskeg areas that were typical for a certain region. Three different sizes of vanes were used. It is shown that road performance is better in muskeg areas with tall tree growth than in areas with little or no tree growth, other factors being equal. No correlation was evident between road condition and type of firm mineral soil substratum. However, an intermediate unstable layer of soft mineral soil is shown to be an important factor in road performance and condition. Although vane testing appears to be a feasible method for determining the shear strength of peat and excellent duplication of results was possible for any particular size of vane, these tests revealed a marked variation in the shear results depending on the vane size. Laboratory test results indicate correlations between moisture content and depth, specific gravity and moisture content, and acidity and carbon content., Reprint from: Highway Research Board Bulletin no. 316, 1962, p. 32-43.