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This paper is devoted to the investigation of the density sorting of grains using water jigging. Experiments achieved in a laboratory scale water jig for two initial binary bed configurations are studied and compared to numerical results. The vertical composition of the deposit is estimated after different number of water pulses to represent the sorting evolution in time. Simulations are based on a multiscale model in which the fluid is solved at a larger scale than the grain diameter using the finite element method, while the grains are considered as rigid bodies and solved using the nonsmooth contact dynamics. Key parameters are numerically varied and observed to determine the sensitivity of the process.

ISBM 2020, RILEM International Symposium on Bituminous Materials , Lyon, FRANCE, 14-/12/2020 - 16/12/2020; The Task Group 2 of the RILEM Technical Committee 264-RAP on non-cold recycling identified the need to gather some insights about possible durability issues associated with the combination of Warm Mix Asphalt (WMA) and of Reclaimed Asphalt (RA) in order to prioritize the characteriza-tion or research needs for relevant damage types. For this purpose, an interna-tional inter-laboratory testing program was launched in 5 different laboratories. This was developed on the basis of the challenges which a road material de-signer commonly faces: reduce the temperature, add RA, but preserve the same properties. Each laboratory characterized, according to its internal protocol, two variations of the same type of mixture (similar grading curve, binder content, etc.): a Hot Mix Asphalt (HMA) without RA taken as reference and a WMA with 40% RA. The performances of all the WMA with 40% RA are then com-pared in order to see if common trends emerge from the different characteriza-tion methods and reveal property issues specific to WMA+RA combinations.

ICSMGE 2017, 19th International Conference on Soil Mechanics and Geotechnical Engineering, SEOUL, COREE, REPUBLIQUE DE, 17-/09/2017 - 22/09/2017; The scouring process represents a significant contributing factor in the destabilising and destruction of civil structures (bridges, earth embankments and buildings) during major flood events, yet our understanding of the mechanisms involved remains highly empirical. These erosion phenomena are especially complex and involve many disciplines like soil mechanics, fluid mechanics or structural mechanics... To overcome this reliance on empiricism, while building general knowledge and proposing optimised methods aimed at diagnostics, advanced warning procedures and infrastructure management, a consortium comprising six complementary Partners has been formed within the project SSHEAR ('Soils, Structures and Hydraulics: Expertise and Applied Research') financially supported by the French National Research Agency (ANR). In this paper, after a presentation of the project, a first assessment of the results achieved since the project started in 2015 is proposed: experimental developments; numerical modelling; feedback in the field.; Les processus d'affouillement sont une cause importante de destruction des constructions (ouvrages d'art, ouvrages en terre et bâtiments) notamment lors des crues majeures. La prise en compte de ces phénomènes d'érosion reste trop empirique, notamment parce qu'ils sont particulièrement complexes et font intervenir de nombreux champs disciplinaires : mécanique des sols, des fluides, des structures. Dans la perspective de dépasser cet empirisme, d'avancer sur l'amélioration des connaissances et finalement d'améliorer les méthodes de diagnostic, d'alerte et de gestion, le projet SSHEAR (« Sols, Structures et Hydraulique : Expertise et Recherche Appliquée ») met en synergie les compétences de 6 partenaires avec le soutien de l'ANR (« Agence Nationale de la Recherche »). Dans cette communication, après une présentation du projet, un premier bilan des résultats obtenus depuis le démarrage en 2015 est proposé : développements expérimentaux, modélisation numérique, observations de terrain.

La compréhension des phénomènes différés affectant le comportement mécanique des géomatériaux est essentielle pour permettre un dimensionnement plus juste des ouvrages. C'est pourquoi nous avons étudié le lien entre les différents essais permettant de caractériser les effets du temps ou de la vitesse sur le comportement mécanique des géomatériaux. Dans un premier temps, nous nous sommes attachés à caractériser l'influence du mode de sollicitation sur l'état de contrainte d'une argile en condition oedométrique. Nous avons réalisé différents types d'essais sur une argile saturée drainée : des essais à vitesse de déformation contrôlée, des essais de fluage et des essais de relaxation. D'après notre étude, il apparaît que l'état de contrainte axial et radial ne dépend pas de la vitesse de consolidation imposée, et cela, sur une large gamme de vitesses. Le chemin de contrainte en condition oedométrique est donc, au regard de nos résultats expérimentaux, à la fois une propriété de nature de l'argile et une propriété d'état du matériau. Pour étudier l'influence des facteurs environnementaux que sont la température et l'humidité relative sur le comportement mécanique de géomatériaux, nous avons développé un dispositif expérimental original permettant de contrôler la contrainte axiale, la température et l'humidité relative de l'éprouvette en condition oedométrique. Le dispositif a été testé sur un sable et sur un béton cellulaire en condition isotherme. Concernant le sable, une série d'essais oedométriques par paliers de chargement a montré que les indices de compression et de gonflement du sable ne semblent pas affectés par la température et l'humidité relative. Cependant, la température modifie le comportement hydro-mécanique du sable. En effet, à 25 °C, le chemin de contrainte et ainsi le coefficient des terres aux repos ne dépendent pas de l'humidité relative, alors qu'à 41 °C, le coefficient des terres aux repos diminue avec l'augmentation de l'humidité relative. Concernant le béton cellulaire, nous avons été contraints à travailler en condition uniaxiale, il a été montré que l'indice de compression augmente avec l'humidité relative et cela quel que soit le niveau de contrainte appliqué. Enfin, une modélisation élasto/visco-plastique a été mise en place pour rendre compte des effets de vitesse sur le comportement mécanique saturé d'un géomatériau. Après avoir discuté du rôle de chaque paramètre, nous avons identifié les paramètres permettant de reproduire l'allure des essais expérimentaux. De plus, après avoir calibré le modèle à l'aide de deux essais CRS, nous avons prédit un essai CRS à une autre vitesse de manière probante A better understanding of deferred phenomena affecting geomaterials behaviour is essential to allow a more efficient design of structures. We studied the link between tests used to characterize deferred effects on the mechanical behavior of geomaterials. First, we focused on the influence of the stress load on the stress path of clay in oedometric condition. We carried out different types of tests on saturated drained clay: strain rate tests, creep tests and relaxation tests. Our study shows that the state of axial and radial stresses and thus the earth coefficient at rest do not depend on the strain rate imposed over a wide range of strain rates. The stress path in oedometric condition is therefore, with regard to our experimental results, both a characteristic of the clay and a property of the state of the sample. To study the influence of environmental factors such as temperature and relative humidity on the mechanical behavior of geomaterials, we developed an original experimental device to control the axial stress, temperature and relative humidity of the specimen in oedometric condition. The device was tested on sand and on cellular concrete i isothermal condition. Regarding the sand, a series of oedometer tests by loading steps showed that the index of compression and the index of swelling of the sand does not seem affected by temperature and relative humidity. However, the temperature modifies the hydro-mechanical behavior of the sand. Indeed, at 25 °C, the stress path and thus the earth coefficient at rest of soil does not depend on relative humidity, whereas at 41 °C, the earth coefficient at rest decreases with an increase in relative humidity. Concerning cellular concrete, we have been forced to work in uniaxial condition, it has been shown that the compression index increases with relative humidity regardless of the level of stress applied.Finally, an elasto/visco-plastic model has been implemented to account for time effects on the mechanical behavior of a saturated geomaterial. After discussing the role of each parameter, we have identified parameters to reproduce results of the experimental tests. In addition, after calibrating the model using two CRS tests, we predicted a CRS test at another strain rate in a convincing manner

The mechanism of the scour process is a most challenging subject. To improve his understanding, a new test, the Wheel Erosion Test (WET), was developed. It consists of a wheel rotating upon a layer of sediments. If the stress produced by the wheel is sufficient, grains are eroded and a scour hole is observed. The dimensions of the scour hole can be characterized by video camera and acoustic measurements., Les mécanismes d'érosion et d'affouillement sont des sujets très complexes. Pour améliorer la caractérisation de ces phénomènes, un nouvel essai, le 'Wheel Erosion Test', a été développé. Il consiste à faire tourner une roue au dessus d'un lit de sédiments. A partir d'une contrainte seuil, une fosse d'érosion est obserÎe et ses dimensions peuvent être mesurées par des méthodes acoustiques ou optiques.

In massive concrete structures, cracking may occur during hardening, especially if autogenous and thermal strains are restrained. The concrete permeability due to this cracking may rise significantly and thus increase leakage (in tank, nuclear containment…) and reduce the durability. The restrained shrinkage ring test is used to study the early age concrete behaviour (delayed strains evolution and cracking). This test shows, at 20 °C and without drying, for a concrete mix which is representative of a French nuclear power plant containment vessel (w/c ratio equal to 0.57), that the amplitude of autogenous shrinkage (about 40 μm/m for the studied concrete mix) is not high enough to cause cracking. Indeed, in this configuration, thermal shrinkage is not significant, whereas this is a major concern for massive structures. Therefore, an active test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the classical restrained shrinkage ring test. It allows to take into account both autogenous and thermal shrinkages. Its principle is to create the thermal strain effects by increasing the temperature of the brass ring (by a fluid circulation) in order to expand it. With this test, the early age cracking due to restrained shrinkage, the influence of reinforcement and construction joints have been experimentally studied. It shows that, as expected, reinforcement leads to an increase of the number of cracks but a decrease of crack widths. Moreover, cracking occurs preferentially at the construction joint.

Lors de la construction de bassins d'infiltration d'eaux de ruissellement urbaines, les caractéristiques des sols de fond de bassin doivent être prises en compte tant du point de vue du risque de colmatage que de celui du transfert de polluants sous forme dissoute ou particulaire colloïdale. L'hétérogénéité des sols (structure, texture) peut influencer les écoulements d'eau. Une expérimentation en colonne de laboratoire avec un milieu poreux hétérogène en présence ou non d'un géotextile a été menée pour étudier l'influence des conditions hydriques (saturées et non saturées) et de la présence du géotextile sur l'écoulement et le transfert colloïdal. L'analyse des courbes d'élution du traceur de l'eau a montré un écoulement hétérogène dans le gravier. Le degré d'homogénéité de l'écoulement a été augmenté par la présence du géotextile dans les deux conditions hydriques du fait d'une modification de l'écoulement dans la zone proche du géotextile. La rétention colloïdale a été modifiée également en présence du géotextile dans les deux conditions hydriques étudiées. Il est montré que l'introduction d'une strate artificielle dans les bassins d'infiltration peut diminuer le transfert colloïdal en augmentant la capacité filtrante du sol.

Comme dans d'autres pays européens, en France, les lignes classiques constituent la plupart du réseau ferroviaire (94%) et elles sont généralement âgées de plus d'un siècle. Aujourd'hui, on est demandé d?améliorer les réseaux pour faire face à une augmentation de la charge du trafic et de la vitesse de service. Dans ce contexte, ce travail de thèse vise à étudier expérimentalement l'influence de la vitesse et de la charge sur le comportement dynamique des matériaux constituant les voies classiques, à travers à la fois le suivi «in-situ» et des essais en laboratoire. Pour les études «in-situ», une section de ligne représentative du réseau classique a été sélectionnée dans le réseau français. Le site choisi a fait l?objet d?une prospection géophysique et géotechnique, ce qui a permis de définir les propriétés géotechniques des différents sols constituant la plateforme. L?impact de la vitesse du train et la charge à l'essieu sur la contrainte verticale, déflection/déformation, et en particulier leurs amplifications ont été évalués avec l?augmentation de la vitesse d?un train d'essai Intercités roulant à des vitesses différentes de 60 km/h à 200 km/h et les différentes charges à l'essieu appliquées par des voitures de passagers et la locomotive. Une analyse statistique est aussi réalisée afin d'évaluer la variabilité de la réponse de la voie et leur amplification dynamique avec la vitesse, en se basant sur les données enregistrées lors des passages de trains commerciaux. On observe que l?'amplification dynamique de la réponse de la voie due à la vitesse des trains est directement liée au rapport entre la vitesse des trains et la vitesse des ondes de surface du site. Un matériau représentative du sol intermédiaire des voies classiques a été préparé et testé dans une cellule triaxiale cyclique pour étudier son comportement mécanique. Deux types de charges, de forme sinusoïdale et de forme M, ont été appliqués et, en outre, deux teneurs en eau ont été examinés. Des variations des paramètres dynamiques des sols tels que le module élastique et le rapport d?amortissement avec le nombre de cycles ont été évalués, et les effets des paramètres de chargement tels que la forme de la charge, l'amplitude de la charge et la fréquence de charge ont été étudiés. L'effet de la teneur en eau a été étudié également. Il a été observé que la réponse de l'énergie développée pendant le chargement cyclique est un paramètre qui gouverne le comportement mécanique des sols à petit et grand nombre de cycles. En outre, la charge en forme sinusoïdale a été trouvée plus agressive que celle en forme de M parce que ce chargement sinusoïdal développe plus d'énergie, engendrant ainsi plus de déformations permanentes du sol à grand nombre de cycles, particulièrement le cas lorsque le sol est saturé. A partir des résultats obtenus sur le terrain et en laboratoire, deux modèles analytiques en 2-D ont été développés permettant de décrire la distribution de contrainte verticale et la propagation des déflections verticales. Certains paramètres mécaniques tels que les modules élastiques des couches de la voie, leurs rapports d'amortissement, leurs épaisseurs, ainsi que la vitesse moyenne des ondes de surface dans la section de voie considérée se sont révélés être les principaux paramètres contrôlant le comportement dynamique de la voie. Une comparaison entre les mesures effectuées sur le terrain et les résultats des essais en laboratoire a été également réalisée. La réponse de la voie sous différents types de trains, TER et TGV avec des charges équivalentes mais avec différentes configurations spatiales des essieux, est présentée. On observe que la réponse en énergie est plus élevée pour TGV que pour TER. Cette plus grande énergie développée suggère une plus grande agressivité vis-à-vis de la structure de la voie. Ainsi, la réponse en énergie est un indicateur important à prendre en compte lors d'un suivi du comportement mécanique d'une voie As in other European countries, in France the conventional lines constitute the main part of the whole railway network (94%) and they are generally over a century old. Nowadays, facing the demand of upgrading both the traffic load and speed, it is of paramount importance to acquire good knowledge on the corresponding impact on the mechanical behaviour of tracks, at both short and long terms. In this context, this PhD work aims at investigating the influence of train speed and axle load on the dynamic behaviour of materials constituting the conventional track-beds, through both ?in-situ? monitoring and laboratory testing. For the field monitoring, a representative track was selected from the French conventional network following well-defined criteria. The selected site underwent a geophysical and geotechnical prospection, allowing the site critical speed and the geotechnical properties of different soils constituting the track-bed to be determined. The first data allowed assessing the influence of the track state conditions and the traffic loading on the measurements of each sensor. The train speed and axle load impacts on the vertical stress, deflection/strain, in particular their amplifications with speed increase were evaluated based on the data with an Intercity test train running at different speeds from 60 km/h to 200 km/h and the different axle loads applied by Coaches (105 kN/axle) and Locomotive (225 kN/axle). A statistical analysis was made to assess the variability of track response and their dynamic amplification with speed based on the data with passages of commercial trains. The dynamic amplification of track response due to train speed was found to be directly related to the ratio of train speed to the surface wave velocity. The laboratory test conditions were defined based on the field measurements. A material representative of an interlayer soil was prepared and tested in a large-scale cyclic triaxial cell to investigate its mechanical behaviour. Both Sine-shaped and M-shaped loads were applied and in addition, two water contents were considered. The variations of dynamic parameters such as resilient modulus and damping ratio with number of cycles were assessed, and the effects of loading parameters such as consolidation pressure, load shape, load amplitude and load frequency were investigated. The effect of water content was studied as well. It was observed that the response of energy developed during cyclic loading is an important parameter controlling the soil mechanical behaviour at both small and large numbers of cycles. Also, the Sine-shaped loading was found more aggressive than M-shaped loading since the former results in higher energy and therefore larger soil deformation. This is particularly the case when the soil is saturated. Based on the results obtained in the field and laboratory, two 2-D analytical models were developed allowing the description of vertical stress and vertical deflection transmissions in track-beds. Some mechanical parameters such as the moduli of track-bed layers, their damping ratios, thicknesses as well as the average track surface wave velocity were found to be the key parameters governing the track dynamic behaviour. A comparison between field and laboratory results was also made. The track response to the loading by different train types, considering equivalent loads but different spatial loading configurations from TER and TGV train axles is presented. It was found that for each monitored position in the track, the response energy was higher for TGV than for TER. This larger developed energy suggests a higher aggressiveness to the track structure. Thus, the energy response is a key indicator to be taken into account when performing a track mechanical behaviour monitoring

Third Coastal and Maritime Mediterranean Conference, FERRARA, ITALIE, 25-/11/2015 - 27/11/2015; La résistance au cisaillement non drainé sur des sols fins et en particulier des sédiments, est un paramètre important pour l'étude de la stabilité de talus, de la circulation des engins sur couches déposées en bassin de lagunage, du suivi de la déshydratation et du séchage naturel, de la consistance et sensibilité des sédiments. La résistance au cisaillement non drainé peut être mise en relation avec la teneur en eau et les limites d'Atterberg. Plusieurs outils sont disponibles pour sa détermination in situ et en laboratoire. Pour l'obtention d'un profil en continu des mesures de Su, les pénétromètres à écoulement - full flow penetrometer - sont utilisés en ingénierie offshore et en modélisation en centrifugeuse avec des outils miniatures. En laboratoire, à l'aide d'un outil miniature, il est nécessaire d'étudier conditions d'utilisation et de valider les mesures acquises. Un T-bar miniature (TBT) a été développé et utilisé en même temps qu'un scissomètre de laboratoire (VST) dans des sols fins reconstitués et des sédiments. Ce dernier outil ne fournit que des mesures ponctuelles et ne permet pas d'effectuer des cycles pénétration-extraction comme le T-bar permettant d'étudier la dégradation des sols. Le T-bar de laboratoire est présenté avec la justification de sa géométrie et des conditions d'utilisation vis-à-vis des recommandations établies par l'ingénierie offshore. Les sols testés et les conditions expérimentales sont brièvement décrits. Lors de premiers essais, les influences de la taille et de la rugosité du diamètre du T-bar sont observées et commentées.

Journées géotechnique Cerema, LACANAU, FRANCE, 13-/10/2015 - 15/10/2015; Présentation des essais de cisaillement réalisés sur des interfaces béton-roche de taille métrique.

Présentation, résultats et analyses de l'essai de faisabilité du projet de recherche EDF-Ifsttar 'CIBEFHY' : essai de cisaillement d'une interface béton roche à l'échelle métrique.

Ce rapport expose l'avancée des travaux concernant la tâche 4 qui porte sur les mesures de vitesse avec contact, et de la tâche 5 qui concerne le comportement de la pollution particulaire dans les réseaux. Le rapport à T0+12 ayant été finalisé en février 2014, les avancées effectuées restent modestes après deux mois. Dans un premier temps, ce rapport rappelle les partenaires impliqués dans cette tâche. Dans un second temps, il donne les résultats concernant les cas étudiés en laboratoire : jonctions de canaux, bifurcations de canaux, coudes et sections droites équipées de banquettes. Dans un troisième temps, il expose les travaux effectués sur le terrain.

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is a major pest that has recently invaded Afro-Eurasia.[br/] Biological control, especially by Trichogramma parasitoids, is considered to be promising as a management tool for this pest. However, further development of Trichogramma-based biocontrol strategies would beneÞt from assessing the impact of released parasitoid offspring on the pest. Under laboratory conditions, we 1) compared the parasitismof five Trichogramma species-strains on the pest-plant system T. absoluta-tomato, and 2) assessed various biological traits of parasitoids, mass-reared on a factitious host (Ephestia kuehniella Zeller), when developing on T. absoluta. In addition, we evaluated the overall efÞciency of two specific Trichogramma species when released under greenhouse conditions in combination with a common natural enemy in tomato crop, the predator Macrolophus pygmaeus Rambur.[br/] Parasitoids emerging from T. absoluta on tomato showed lower parasitism rates and poor biological traits, for example, wing deformations, reduced longevity, when compared with the control reared on the factitious host. Under greenhouse conditions, the parasitoids that developed on T. absoluta after initial releases contributed little to biological control of T. absoluta, and parasitism tended to be lower when the predator was present. However, a slightly higher T. absoluta control level was achieved by combining the predator and release of the parasitoid Trichogramma achaeae Nagaraja and Nagarkatti.[br/] This study shows that Trichogramma parasitoids may not build up populations on the T. absolutaÐtomato system, but that Trichogramma parasitoids can be used in combination with M. pygmaeus to enhance biological control of the pest in tomato crops.

In recent years, warm mix asphalt (WMA) is widely used for reducing energy requirements and emissions in comparison to hot mix asphalt (HMA) industry. Besides, the use of rubberized bitumen has been spread out mainly due to environmental aspects, but high mixing and compaction temperatures are necessary due to the higher viscosity of this bitumen. A WMA mixture (using a surfactant technology) with asphalt rubber was evaluated in a field project, together with a control section. WMA mixing and placing temperature was 25ºC lower than HMA, from about 170 to 145ºC. Tensile indirect strength, resilient modulus and moisture resistance tests were conducted with loose mixture collected in the plant to evaluate field performance. Based on these tests in laboratory, the WMA technologies all performed equal to the control mixture. In addition, a simplified estimate of decreasing in fuel consumption was also determined and the results showed that the use of WMA was advantageous.

After being used as a biocontrol agent against aphids for decades without harmful consequences, the Asian harlequin ladybird Harmonia axyridis has suddenly become an invasive pest on a worldwide scale. We investigate the impact of captive breeding on several traits of this ladybird such as genetic diversity, fecundity, survival and pathogen resistance. We conducted an experiment in the laboratory to compare the fecundity and the susceptibility to the entomopathogenic fungus Beauveria bassiana of wild and biocontrol adults of H. axyridis. We compiled these new findings with already published data. Altogether, our findings suggest that mass rearing of biological control agents may strongly impact genetic diversity and life-history traits. We discuss how such changes may subsequently affect the fitness of biological control strains in natural environments.

Coaxiality between the principal directions of the stress tensor and the principal directions of the plastic strain increment tensor is assumed in conventional plasticity models. In order to investigate coaxiality, or non-coaxiality, between these two principal directions, a series of drained tests on dry Hostun sand was carried out using a precision Hollow Cylinder Apparatus (HCA). The applied stress path includes large Principal Stress Axes Rotation (PSAR). Two of the three principal stresses are kept constant. Therefore, among the three principal stresses, only the intermediate principal stress, which is confining pressure (same pressure outside the hollow cylinder for internal and external lateral surfaces), changes during loading. During these tests, at different stress levels, elastic (or quasi-elastic) properties are also investigated, using small amplitude quasi-static cycles. These small cycles are performed in two different directions by successively changing only the axial stress σzz or the shear stress σθz. Elastic experimental properties are well simulated using the DI Bendetto-Geoffroy-Sauzeat (DBGS) hypo-elastic model, which takes into account PSAR. For each test, the elastic part of deformation is calculated using the DBGS model and removed from global strain so that it is possible to to focus only on the irreversible part (plastic part). Then, the principal directions of stress and plastic strain increment are compared. Experimental results show that there is no coaxiality between these directions. This observation attests to the existence of a non-coaxial plasticity. In addition, the coupling between tge coaxial and non-coaxial part is clearly shown. Experimental results reveal that the plastic strain part is very important for the first large amplitude cycles and remains greater than the elastic part even after 20 cycles.

Several tests, devoted to the study of cracking due to autogenous and drying shrinkage, exist in the literature. They are generally not relevant for the study of massive structures for which thermal strains plays a key role. Therefore, an active ring test has been developed to study cracking due to restrained thermal shrinkage. This test is an evolution of the restrained shrinkage ring test which allows us to take into account both autogenous and thermal shrinkage. With this test, the early age cracking due to thermal restrained shrinkage (effect of the temperature rate), the influence of reinforcement and construction joints have been studied (Briffaut et al. (2011) [1] ). Nevertheless, in this test, several phenomena occur simultaneously (hydration, shrinkage, creep…) and their effect cannot be easily decoupled. So, complementary tests have been performed to study each phenomenon separately and the ring test has been numerically simulated in order to identify coupling between creep and damage and to quantify the strength decrease due to construction joints. A good agreement between experimental and numerical results has been obtained for ring with reinforcement and construction joints. With the proposed model and the identified materials parameters validated on the active restrained ring test, numerical simulations of the construction of a real massive structure have been performed, and a parametric study has been achieved to highlight the creep effect.

Deux déchets industriels contenant 10-15% d’azote, moitié sous forme nitreuse et moitié sous forme nitrique, ont servi de source d’azote à des cultures de blé et de maïs. En incubation de laboratoire, la conversion des nitrites en nitrates varie de 22 à 52 mg.kg-1.semaine-1 d’azote en sol neutre pour des températures de 10, 15 et 20 °C; en sol acide au moins un tiers de l’azote nitreux est perdu par dénitrification chimique et le fonctionnement d’une partie de la microflore semble perturbé : minéralisation accrue du carbone et production d’ammonium. Au champ la vitesse de conversion est conforme aux résultats de laboratoire lorsque le déchet est apporté en solution mais diminue de moitié avec les produits solides. La persistance du nitrite dans le sol est fonction de la dose apportée. Un apport sur blé à la montaison pénalise légèrement le rendement en grain (- 5%), les nitrites ralentissant l’assimilation azotée des plantes. Sur maïs au semis la germination est fortement perturbée par les nitrites, entraînant des diminutions de rendement en grain pouvant atteindre 30% selon la dose d’apport. Lorsque la température du sol atteint 10 °C un apport de 50 kg.ha-1 d’azote nitreux sur culture implantée (blé) permettrait la valorisation de ce type de déchets par la voie agricole., Two batches of industrial waste containing 10-15% oxidized inorganic N, half of which was in nitrite form, were used as N source for wheat and maize crops. In laboratory incubation the conversion of nitrite to nitrate varied from 22-52 mg N.kg soil-1wk-1 at temperatures of 10, 15 and 20 °C in soil with a neutral pH. In acid soil at least one-third of the nitrite N was lost by chemical denitrification and the functioning of part of the microflora appeared to be perturbed: there was an increased mineralization of C and production of ammonia. In the field, the rate of conversion corresponded with laboratory results when the waste was applied as a solution, but halved with solid products. Persistance of nitrite in the soil was a function of the dose added. Application to wheat at the beginning of stem elongation slightly reduced grain yield (- 5%), with nitrites slowing down N assimilation of the plants. Applied to maize at sowing, germination was strongly affected by nitrites, resulting in a diminution of grain yield which reached 30% depending on the application dose. When soil temperature had attained 10 °C, an application of 50 kg.ha-1 of oxidized N to the growing crop (wheat) allowed the 2 batches of waste to be used in agriculture.

Présentation de la technique d'expansion résiduelle pour la réaction sulfatique interne du béton et exemples d'application.

The temporal characterization of the failure risk in rock masses can be better known by tracking progression of cracks due to weathering. So this study aims at using a non-destructive method, the resonant frequency measurement, to estimate the failure scenario of a rock sample. The experiments focus on determining resonant frequency values of two limestone rocks at different known states of uniaxial stress which are linked to states of cracking. Then the resonant frequency is measured on the same limestone rocks submitted to a global mechanical stress : freeze-thaw cycles. First this study shows that the resonant frequency can give a model of the failure scenario of a rock sample submitted to local mechanical stresses. Besides the resonant frequency variations with global stresses are similar to the trend previously observed with uniaxial stresses. So this study enables to predict its failure scenario considering the trend of the resonant frequency values.

La gestion des eaux pluviales aéroportuaires en période de viabilité hivernale pose la question du devenir de la charge organique liée à l'utilisation de fondants organiques. Deux séries d'essais de biodégradation aérobie ont été réalisées en laboratoire en réacteurs statiques afin de tester l'influence de la température (20, 10 et 5°C), de la quantité de biomasse et des nutriments (phosphore et azote) sur la dégradation du propylène glycol et de l'acétate de potassium, principes actifs de produits respectivement dégivrant et déverglaçant, et des effluents pluviaux prélevés sur deux aéroports français après utilisation de fondants. Ces essais montrent que les principes actifs , une fois un temps de latence passé se dégradent plus rapidement que les effluents chargés en fondants. Cette différence pourrait être liée à une légère inhibition de la dégradation des effluents par la présence d'additifs (dont les benzotriazoles et nonylphénols) issus des préparations commerciales des fondants et/ou autres sources aéroportuaires. Ces essais montrent que la dégradation de la charge organique est effective mais fortement ralentie à faible température. Pour que cette dégradation soit suffisamment efficace à 5°C et compatible avec le temps de séjour des effluents dans le système d'assainissement, un apport de biomasses et de nutriments est nécessaire.

Summary Understanding and modeling both flow and solute transport within heterogeneous soils, such as a macroporous soil, are of primary concern nowadays in tackling the problem of predicting water resources and soil contamination. Traditional conceptual approaches have proven inadequate for describing preferential solute transfer through macropores and the dependence of such transfer on macropore characteristics (continuity, tortuosity, hydraulic properties, etc.). The enhancement of preferential flow and nonreactive solute transfer through a cylindrical macropore in a sandy matrix has been studied under hydric conditions through laboratory column experiments. Numerical modeling based on the Darcy–Buckingham Law for both the macropore and matrix along with macropore–matrix system geometry is not able to generate an accurate fit. An additional modeling step has indicated that the preferential flow path zone must be considered as extending around the macropore. Such a result illustrates that the major effect of macropores may be much more significant than would be predicted through the typical, conceptual dual-permeability approaches and thus deserves further research.

In order to estimate the influence of bitumen on the resistance to cracking and fatigue behaviour of bituminous mixes, a specifie test has been developed to estimate fracture properties. A thin film of binder between two steel protuberances, simulating the pseudo contact of two aggregates, is subjected to successive tension loads with a constant strain rate during the test. Formation and evolution of the crack size during the test was investigated using numerical methods. This paper deals with the combination of the experimental evolution of the sample stiffness and modelling of the considered test by finite element method. The modelling method, described here integrates both viscoelasticity with Prony series and the sample geometry. A quantitative method using stress intensity factor and displacement intensity factor is also presented to study the effect of strain rate on propagation of crack

The pozzolanic activity of four heated powders containing different clays has been tested. Mineral transformations during calcination from 20 to 900 °C have been followed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Compressive strength tests were performed at 1, 7 and 28 days on cement-clay mortars using 30% of pozzolanic material as a replacement by mass for cement. Calcination temperatures corresponded to the stages of potentially high reactivity identified by XRD. Results indicated that there exists incompatibility between clay minerals which can not be activated at the same temperatures. Products of recrystallisation of the earlier activated clay were already formed when the second clay type was activated. Concerning the type and the abundance of clay minerals in the raw material, this study evidences that the compressive strength is, at first approximation, correlated with the percentage of activated clay and less with the nature of the clay assemblage.

In the sustainable development context, road companies have adopted an approach which aims at accelerating convergence between environmental requirements and development of energy-saving materials called warm and half-warm asphalt mixes. This study, realised in Laboratoire Central des Ponts et Chaussées (LCPC) within the framework of a partnership between EIFFAGE Travaux Publics and LCPC aimed at determining the influence of the mix composition on the environmental properties of the half-warm mix asphalts compared to hot mix asphalt acting as reference materials. By means of the factorial experiment design approach, this study highlights the influence of the bitumen chemical nature, the additive origin and the water content on fumes generated during the manufacturing stage.

Under the framework of OECD/CEMT JTRC, an international team of road research laboratories worked together in order to evaluate technical solutions for long-life pavement. As a matter of fact, there are in many countries highly trafficked road sections where any traffic disruption brings high external costs. For such a case, the aim was to study wearing courses that could last several decades with no maintenance. The paper presents an innovative technical solution, called HPCM (High-Performance Cementitious Material), consisting of a thin layer of ultra-high performance fibre-reinforced mortar with calcined bauxite aggregate embedded in the surface at the fresh state. Many laboratory and two full-scale tests were carried out, dealing with surface resistance (abrasion, wear, shocks, freeze-and-thaw, acid attacks), cracking under restrained shrinkage and fatigue resistance due to heavy traffic loading. New projects were launched recently to continue this coordinated research : a French national project called CLEAN, and an international project called LLPS3. Both of them aim at building circulated road sections to fully validate this promising technology.

Ce travail de thèse concerne l'excavabilité des matériaux cimentaires pour tranchées. Il s'agit de définir des seuils d'excavabilité à la pioche de terrassement à partir d'essais de laboratoire. La bibliographie a montré l'existence de critères empiriques d'excavabilité ; cependant, ils sont insuffisamment discriminants, et ne prennent pas en compte l'énergie d'excavation, l'âge, la formulation ou le squelette granulaire des matériaux. Nous avons donc proposé une démarche scientifique, combinant une approche expérimentale en laboratoire et in situ à une approche numérique, fondée sur la méthode aux éléments finis en grandes déformations. L'étude a été réalisée sur deux familles de matériaux (mortiers à forte teneur en air et bétons très maigres) caractérisés par des essais mécaniques classiques. Un essai original de poinçonnement en laboratoire a été développé. Des simulations tridimensionnelles sur une tranchée soumise à une sollicitation équivalente à un coup de pioche, comparées à des simulations bidimensionnelles en axisymétrie sur une éprouvette soumise à un poinçonnement, ont permis de dimensionner l'essai. Celui-ci consiste à mesurer un enfoncement pour un niveau d'énergie analogue à celui d'un coup de pioche. En parallèle, un essai d'excavation mécanisé en vraie grandeur, instrumenté, consistant à mesurer l'enfoncement à la pioche et le volume excavé, a été mis au point et validé par des piochages manuels sur tranchées. L'exploitation de l'ensemble des mesures a permis la construction d'un modèle prédictif de volume de matériau excavé, grâce auquel on a construit un abaque préconisant des seuils d'excavabilité, en termes d'enfoncements au poinçon en fonction du diamètre maximal des granulats du matériau testé. The present work deals with the study of the excavatability of cement treated materials with a pick. It aims at proposing thresholds of excavatability thanks to a characterization in laboratory. Currently, there are either some classification systems or some empirical criteria of excavatability but they do not refer to the power of the digging facility nor to the age, the mix design and the granular skeleton of the material to be excavated. The study encompasses an experimental approach in laboratory and in the field, together with a numerical approach with the finite element method implemented in a geotechnical code. We focussed on the confection of an air-entrained mortar and a very lean concrete, which were characterized by classical strength tests. According to 3D and 2D axi-symmetric simulations of the penetration pick process, we set up a laboratory-punching test in order to study work-penetration curves. A field mechanized, operator-independent excavation test was developed, whom relevance was confirmed by comparison with manual excavations. Penetration depth and volume were measured for a series of trenches. Finally, all laboratory and field results were analysed and discussed. A predictive model was developed for the volume of excavated materials, from which a chart was built, suggesting excavatability thresholds as a function of penetration depth and maximum size of aggregate.

This paper presents the results of a round robin test (RRT) on binder fatigue, with data received from 11 participating laboratories. Most data were obtained with a Dynamic Shear Rheometer (DSR) equipment, one laboratory used a tension-compressiontest. In a first stage, the RRT consisted of three binders, two unmodified binders and onepolymer modified binder. These three binders had almost the same stiffness level at the testing conditions, 10°C and 10 Hz. Fatigue tests were conducted at three strain levels, and each strain level was measured in three repeats. For each test it was asked to follow the small strain stiffness during an equilibration time of 30 minutes. A second stage of this RRT including two more binders is foreseen. The same three binders were also tested in two and in four point bending mix fatigue tests. The analysis was separated into two parts, in a first part the repeatability and reproducibility of the small strain equilibrium stiffness was evaluated and in a second part the fatigue data were analyzed. Small strain stiffness data showed that the repeatability and reproducibility of G* is still not very high, and possible reasons are under evaluation. The analysis of the fatigue data showed that the overall reproducibility was not good. But when all participants that did in some way not follow the preparation procedure or that had problems with recording, were excluded, it was found that for 6 of the participating laboratories the fatigue properties gave good repeatability and reproducibility levels, for the two unmodified binders in this study. Each laboratory could distinguish the better fatigue life of the polymer modified binder compared to the unmodified binders as was also confirmed by mixture tests. This shows that the binder behavior plays an important role in the fatigue behavior of the mix, and that a binder test should be able to evaluate this role. The binder fatigue test can be used as a surrogate test for mixture fatigue, implying considerable time savings in sample preparation, however the testing of the binders is still time consuming.

The RILEM TC-ATB-TG5, in charge of recycling of bituminous materials has decided to develop a laboratory procedure with the aim of reproducing the ageing of bituminous materials until the end of their service life (milled product). This procedure will help to assess the recyclability of mixtures and will allow Recycled Asphalt Pavement (RAP) production in the laboratory in a realistic way. The ageing of bituminous materials is mainly linked to the ageing of the binder and is normally separated into short and long-term ageing : The short-term ageing simulating ageing caused by the manufacture of the material in the mixing plant, transport and paving, especially the necessity to increase the binder temperature up to 160-190°C according to the type of binder and material to be manufactured. The long-term ageing simulating the influence of the climatic conditions and traffic loading on ageing during service life. In the framework of an LCPC fatigue carousel experiment, a bituminous material with a 35/50 pure bitumen was laid in January 2008. Loose mix and components (aggregates, bitumen) of the mix have been sampled to carry out a laboratory ageing round robin test, organised between the labs of the RILEM group. Also, on the fatigue carousel, coring will be carried out at several intervals to follow the evolution of the material. In this paper, a state of the art regarding the existing methodologies for the laboratory ageing of bituminous materials is presented as well as the round Robin test, including the tested ageing procedures and the tests chosen to validate these procedures according to the field site data. The first results are discussed with the focus on distribution analysis.

From a French-Brazilian partnership among Escola Politécnica da Universidade de São Paulo (LTP - Laboratory of Pavement Technology), Ecole Spéciale de Travaux Publics ESTP (GREMACOR Laboratory) and Laboratoire Central des Ponts et Chaussées (LCPC Division SMIT), a study on warm mixes asphalt was developed. Since 2003, new asphalt mixes that are set between hot and cold mixes have been developed with the purpose of reducing mixing and compaction temperatures of hot mixes asphalt, yet maintaining the same performance. After selecting one technique that employs an additive, the temperature for producing mixes of which is 110ºC, the study was concentrated on the design of these new mixes in laboratory, by using two methodologies for evaluating the effect of the additive and the decrease in temperature on the performance of the mixture. Two similar classic designs of dense asphalt concrete with usual materials were tested : Béton Bitumineux Semi-Grenu 0/10 Class 2 in France and Grading C DNIT in Brazil. The evaluation considered compaction (air voids content) and moisture susceptibility. The first results lead to discuss the relevance of some tests to the real performance of the warm mixes tested. Besides, for complementing the technical aspect of this study from an environmental viewpoint, additional tests related to organic compounds emissions during the production in laboratory were carried out by using a TOC (Total Organic Compounds) Analyzer.

L'instrumentation des chaussées, habituellement réalisée grâce à des jauges à fil résistant, est un outil indispensable aux recherches expérimentales visant à l'optimisation des techniques de construction et d'entretien des réseaux routiers. Cet article porte sur la possibilité de remplacer des capteurs électriques par des fibres optiques noyées dans des enrobés bitumineux mis en oeuvre soit à chaud (technique de référence), soit à froid tels que les graves-émulsion afin de bénéficier des facilités de multiplexage, voire même de mesures réparties sur des distances kilométriques. Nous avons démontré, à travers des essais de laboratoire puis deux tests sur chantier en vraie grandeur, la faisabilité d'introduire des fibres optiques dans des chaussées, malgré des conditions très sévères de mise en oeuvre. Les réponses des extensomètres à fibre optique de type Bragg sont en bon accord avec celles des capteurs usuels à fils résistants ; les tous premiers tests mettant à profit la technologie de mesure répartie «Optical Backscattered Reflectometry» sont encourageants.

Acoustic Doppler flow-meters are commonly used for continuously measuring flow-rates in sewers. They rely on velocity sensors which provide data supposed to be representative, but not equal, to the mean velocity of the flow. The relationship between a measured value and the actual mean velocity of the flow depends on the volume sampled by the velocity sensor, and on the hydrodynamic features of the measuring site. This paper focuses on the first item, because parameters of sensors are often little detailed in manufacturers’ specification sheets. The principles of testing procedures are outlined, and their implementation in an experimental benchmark is presented, along with the results obtained on a panel of flow-meters.

Le « Crumb test », essai normalisé par l'ASTM, permet une classification simple des sols selon leur sensibilité à la dispersion grâce à des évaluations visuelles donc essentiellement qualitatives. Nous proposons ici une modification de l'appareillage et une amélioration du protocole d'essai afin d'obtenir des résultats quantitatifs et une meilleure caractérisation de la dispersion des sols.

Under the framework of OECD/CEMT JTRC, an international team of road research laboratories worked together in order to evaluate technical solutions for long-life pavement. As a matter of fact, there are in many countries highly trafficked road sections where any traffic disruption brings high external costs. For such a case, the aim was to study wearing courses that could last several decades with no maintenance. The paper briefly presents an innovative technical solution, called HPCM (High-Performance Cementitious Material), consisting of a thin layer of ultra-high performance fibre-reinforced mortar with calcined bauxite aggregate embedded in the surface when in a fresh state. Many laboratory and two full-scale tests were carried out, dealing with surface resistance (abrasion, wear, shocks, freeze-and-thaw, acid attacks), cracking under restrained shrinkage and fatigue resistance due to heavy traffic loading. Although this material still requires some additional research to be implemented on scale-1 road sites, there are good expectations of its potential durability.

For several years, insofar as environmental criteria have been stricter and stricter, new moderated temperature coating and mixing technologies said "warm" - at around 130°C - or even "half-warm" - under 100°C - have appeared. This study carried out in the Laboratoire Central des Ponts et Chaussées within the framework of the partnership between EIFFAGE Travaux Publics and LCPC aimed at determining the influence of parameters such as manufacturing temperature and the additives used on the Total Organic Compounds (TOC) emissions provided from manufactured in laboratory the so-called low energy asphalt LEA around 100°C compared to traditional hot mix asphalt around 160°C. This study shows that a decrease of manufacturing temperature leads to a reduction in the level of TOC emission. The results obtained indicate that environmental properties depend on manufacturing temperature and processes (half-warm and hot mix asphalts). At short-term, the presence of steam water in half-warm mix asphalt tends to favour the TOC emission. This phenomenon could be explained by a stripping water effect. On the contrary at both mid-term and long-term, organic emissions provided by warm bitumen mixes are much lower than those of hot asphalt mixes according to the manufacturing temperature difference. However, this study has to be seen in view of the discontinuous manufacturing process used in laboratory which difference, of course, from the continuous one which may be used in plant.

Roads geometrical design rest partly on relations between the allowed speed of use, the curvature of the plotting and the banking. These relations have sometimes old justifications as in France where the documents used date from 1994. Work presented here comes in the line off a checking approach of these calculation means. In this direction, a preliminary trial run was carried out with a highly instrumented test vehicle rolling in a turn. The road wetting state influence was evaluated for dry and streaming levels. Comparison between the existing relations 'speed-curvature' and the experiments show that the rules include safety coefficients to take into account the variety of the road usages and the model simplicity. Thus, the users safety is not always assured for the using rules can be broken, if appearing badly founded. So, experiments can help to determine a signage more adapted to the encountered situations, and thus, more respected. Later studies will make it possible to extend this confrontation to various bankings, intermediate wetting states and to a panel of vehicles. These researches will finally contribute to the qualification of road safety offer in relation to the various categories of vehicles which it has to accomodate.

Ce mémoire d'habilitation à diriger les recherches de Philippe Reiffsteck comporte quatre chapitres, chacun illustrant les recherches et les contributions sur le thème de l'amélioration du modèle géotechnique, qui est au c½ur du projet scientifique : 1-Rhéologie expérimentale et théorique des sols naturels des petites aux grandes déformations ainsi que sous sollicitations réellement tridimensionnelles ; 2-Comportement des matériaux à texture ou comportement atypique ne pouvant rentrer dans le cadre précédent ; 3-Reconnaissance des sols et des sites : il s'agit d'améliorer la caractérisation des terrains par le biais du développement de nouvelles techniques d'essai ; 4-L'interaction des sols avec l'eau, lorsque cette dernière phase liquide mobile provoque l'instabilité de la phase solide. This thesis of accreditation to supervise research presented by Philip Reiffsteck include four chapters, each illustrating the research and contributions on the theme of improving the geotechnical model, which is at the heart of the scientific project: 1 - Experimental and theoretical rheology of natural soils from small to large deformations and stresses in real three-dimensional ; 2 - Behaviour of Materials with texture or atypical behavior which can not return to the previous frame ; 3 - Onvestigation and monitoring of soils and sites: trend to better characterization of ground through the development of new testing techniques ; 4 - The interaction of soil with water when the latter mobile phase fluid causes instability of the solid phase.

Anisotropy is a mechanical characteristic of soil behaviour; this characteristic is widely admitted in case of overconsolidated or layer deposited soils. This feature is generally overlooked in projects and ignored in laboratory studies. The assumption of isotropic behavior of soils is widely used in practice in order to simplify calculations and ease of design of geotechnical structures. Use of isotropic behavior laws for anisotropic material or not taking account of anisotropy in the calculations result in poor assessment of structures stability. An approach for observe and underscore the anisotropy has been implemented during this work to identify the influence of this phenomenon. We studied for this purpose two main types of soil anisotropy:- induced anisotropy, case of "homogeneous" soil with anisotropic behavior due to historical loads,- inherent anisotropy, case of soil with structural anisotropy. We followed an experimental program based on a laboratory study of soil samples that were not reconstituted to simulate a natural soil accurately but to have a marked anisotropy so that we can observe unequivocal. We just wanted to create a behavior of reference for anisotropic soil and study their anisotropic behavior. The works of this thesis consist of studying in laboratory the behaviour of two types of anisotropy (inherent and induced) of soils under various loads in order to characterize:- the variation of the elasticity parameters of soils according to type of load at small strains,- the evolution of elastic domain from small to high strains level,- the apparition of plastic deformations and the yield surface,- the experimental flow rules. Obtained results showed that the transverse anisotropy influence significantly on the behaviour of soil near the civil engineering works such as diaphragm wall, deep foundations or tunnels. The perspective of this experimental work is to improve constitutive models for soils in numerical modelling tools such as finite element method used for design of civil engineering works., L'anisotropie est une caractéristique du comportement mécanique des sols dont l'existence est bien connue dans le cas des sols surconsolidés ou déposés par couches au cours de leur formation. Généralement cette caractéristique est négligée dans les projets et ignorée lors des études en laboratoire. L'hypothèse du comportement isotrope des sols est ainsi très largement utilisée en pratique pour des raisons de simplification des calculs et de facilité de dimensionnement des ouvrages. L'emploi des lois de comportement isotrope pour un matériau anisotrope ou la non prise en compte de l'anisotropie dans les calculs des massif de sols entraîne une mauvaise appréciation de la stabilité des ouvrages en service. Une démarche d'observation et de mise en évidence de l'anisotropie a donc été mise en oeuvre durant ce travail afin de cerner l'influence de ce phénomène. Nous avons étudié à ces fins deux types principaux d'anisotropie des sols :-l'anisotropie induite, cas des sols « homogènes » ayant un comportement anisotrope, due à des surcharges historiques,-l'anisotropie inhérente, cas de l'anisotropie structurelle des sols. Nous avons suivi un programme expérimental s'appuyant sur une étude en laboratoire d'éprouvettes de sol reconstitué qui n'étaient pas destinées à simuler un sol naturel précis mais à présenter une forte anisotropie afin que l'on puisse l'observer sans équivoque. Nous avons voulu simplement créer un comportement de référence pour les sols anisotropes et étudier leur comportement anisotrope. Le travail a consisté à étudier en laboratoire le comportement de sols à anisotropie matérielle ou de chargement sous chemins de sollicitation triaxiaux pour caractériser :-l'évolution du domaine élastique des petites aux grandes déformations,-l'apparition de la plasticité et lors de l'atteinte de la surface de charge,-la loi d'écoulement expérimentale. La forme de la surface de charge et l'influence de l'anisotropie transverse sur la loi d'écoulement sont en effet des éléments importants du comportement du sol à proximité des ouvrages de génie civil tels que les parois de soutènement, les fondations ou les tunnels. Une des retombées du travail expérimental a été de tester des modèles de comportement utilisés classiquement pour ces types de sollicitations, dans les outils de calcul comme la modélisation des ouvrages par éléments finis.

In a political context in which energy and environmental stokes become increasingly stron, road engineering evolves to energy savings and environmentally friendly practices. In this context, cold mixes treated with bitumen emulsion appear as suitable techniques. Cold mix design and manufacture are empirical and usually controlled thanks to local competences. Based on experimental principles, these methods do not provide fundamental answers to issues such as mixing, transport, workability, compactability, mechanical resistance and coating quality. A research program is started at LCPC with the collaboration of the French Road and Bridges Regiional Laboratories to answer this waiting. An emulsion treated gravel (GE 0/14) with a residual bitumen content of 4,5% ws implemented on a French experimental jobsite in October 2006. Loose jobsite materials and samples manufactured in Laboratory with materials (aggregates and emulsion) coming from jobsite have been characterized. Traditional tests used in the French hot mix design methodology as well as more specific techniques such as triaxial apparatus for cyclic loadings, used to assess mechanical characteristic of unbound granular materials, have been used. This paper presents current normative and also innovating properties linked to implementation behaviour, rheological behaviour and time-dependance (cohesion increase) of emulsion treated gravel.

Increasingly there are more demanding health and environmental criteria involved in the construction field and thus in the road construction and maintenance domain. This requires a better understanding of the fumes generated during the manufacturing of hydrocarbon based materials. This study carried out at the Laboratoire Central des Ponts et Chaussées (LCPC) is part of a research partnership between Shell Bitumen and LCPC in order to determine the nature of the organic compounds emitted during mixing of hydrocarbon maerials used as road construction products, such as the fundamental parameters influencing emissions (mixture features an process used). These organic components include Polycyclic Aromatic Hydrocarbons (PAHs) and Total Organic Compounds (TOC). In this study LCPC has developed a device allowing the collection of fumes from bituminous mixtures. The analysis of emitted TOC was continuously carried out during mixing, using a FID type TOC analyser. The analysis of PAHs trapped on filters was performed in the Shell Bitumen laboratory using high pressure liquid chromatography HPLC equipped with a fluorescence detector. Firstly, feasibility measurements were performed to establish a reliable test protocol and to determine the test repeatability. Then, the evolution of the organic emissions with time was studied. The results obtained highlight the influence of mixing conditions on the nature and the quantity of the emitted compounds.

L'étude présentée dans cet article vise, au travers d'une méthodologie de caractérisation des propriétés des granulats, à mieux connaître la dynamique d'évolution du polissage des microrugosités de revêtements routiers. Si les études de formulation des enrobés et le respect des normes relatives aux constituants permettent une assez bonne prévision de la texture des revêtements neufs, il est en revanche beaucoup plus difficile de prévoir la durabilité de leurs propriétés en fonction du trafic et des conditions climatiques, notamment celle de la microtexture qui évolue par polissage. Pourtant, pouvoir maîtriser cette prévision afin d'anticiper la gestion de l'entretien dès le stade de la conception constitue un enjeu important pour les gestionnaires routiers. Il est probable, dans le contexte actuel, que les marchés s'orientent de plus en plus vers les obligations de résultats, d'où la nécessité de prévoir les performances d'usage. Un moyen d'essai innovant est présenté au laboratoire « la machine Wehner et Schulze », qui simule le polissage des granulats et des surfaces de revêtements routiers. Les résultats obtenus sur quatre natures pétrographiques sont exposés, avec une corrélation entre le Polished Stone Value (PSV) des granulats et le frottement correspondant mesuré avec cette machine, puis une loi simulant la dynamique de polissage des granulats est proposée.

This paper presents a laboratory test method for the prediction of the skit-resistance evolution due to the traffic. This work has been carried out at LCPC since 2004 and aims at providing road engineers and managers with tools to optimize asphalt mixes and forecast the road maintenance. Results are first presented on the test method simulating the polishing process on road specimens. The so-called Wehner/Schulze (WS) polishing and friction machine is briefly described. The polishing procedure is given. Simulated friction-time curves are compared to actual data obtained from trafficked roads. This step validates the relevance of the test method regarding its capability to reproduce actual skid-resistance evolutions. Comparisons are then performed between friction-time curves of respectively asphalt- and aggregate specimens. This step is important since results show to that extent polishing tests on aggregates could be used to assess the behaviour of asphalt mixes. The relationship between WS and PSV tests for the aggregate component is also discussed. The last part of the paper deals with the polishing test duration (N) necessary to reach a given friction value, and its relationship with the traffic (T). It is shown that a linear relationship N = k.T is a good approximation. Values of the "k" factor are presented and discussed. Attempts to predict actual skid-resistance evolutions with traffic from Wehner/Schulze tests are presented.