Evaluation of alkali-activated binders suitability for the stabilization/solidification of tunnel boring muds

In Europe, two major civil engineering projects, the “Grand Paris” automatic metro lines and the “Lyon-Turin” high speed railway tunnel, brought forth for the construction industry an unprecedented prerequisite within schemes of this scale: the necessity to recycle all forms of waste that comes out of the excavation process. By 2030, up to 100 million tons of muds retrieved from the boring operations, likely contaminated with sulphate and heavy metals, will have to be dealt with. Please click Additional Files below to see the full abstract

Relations entre la composition, la structure et les propriétés thermo-mécaniques des matériaux bitumineux

Le mémoire d'Habilitation à Diriger les Recherches (HDR) de François OLARD présente les principaux travaux de recherche et de diffusion scientifique, depuis sa thèse (2000-2003) jusqu'à aujourd'hui. Comme l'indique en partie le titre du mémoire - " Relations entre la composition, la structure et les propriétés thermo-mécaniques des matériaux bitumineux " -, le fil conducteur de ses travaux de recherche est l'optimisation des performances des matériaux bitumineux par une meilleure compréhension des relations entre leur composition, leur structure et leurs propriétés thermo-mécaniques. Une particularité des travaux de recherche de François OLARD tient à son statut de responsable de projets R&D en entreprise, impliquant la mise en adéquation du savoir et du besoin industriel. Le mémoire d'Habilitation à Diriger les Recherches met ainsi en exergue que nombre d'innovations ont pu naître de l'échange entre recherches appliquée et fondamentale, participant ainsi à l'évolution indispensable du savoir-faire en formulation et en production des matériaux bitumineux. Six thématiques majeures ont été abordées au cours des travaux de recherche: 1) Comportement thermo-mécanique des enrobés bitumineux à basses températures. Relation entre les propriétés du liant et de l'enrobé. 2) Influence des propriétés élastiques ou viscoélastiques des revêtements sur le comportement des ponts à dalle orthotrope (Projet ANR ORTHOPLUS). 3) Formulation d'enrobés bitumineux à hautes performances grâce à l'optimisation de l'empilement granulaire et l'emploi de bitumes modifiés en polymères. 4) Propriétés viscoélastiques linéaires et en fatigue des enrobés bitumineux contenant des agrégats d'enrobés recyclés. 5) Comportement des matériaux composites traités au liant hydraulique et des bétons compactés routiers incluant des fraisâts bitumineux et des fibres métalliques (Projet ANR RECYROUTE). 6) Procédés d'enrobage à basses émissions et à température réduite: enrobés dits " semi-tièdes ". Les thématiques 2 à 4 sont très liées et découlent pour partie du travail initial réalisé en thèse (thématique 1). Ainsi, les approches expérimentales et de modélisation des matériaux bitumineux, testés dans le domaine linéaire principalement, y sont très proches. La thématique 5 présente quant à elle une démarche expérimentale et d'analyse similaire, mais appliquée à deux familles de matériaux composites (graves et bétons) traitées au liant hydraulique et incluant des fraisâts bitumineux. La présence de ces fraisâts bitumineux confère en effet un comportement visco-élastique aux mélanges testés. La thématique 6 présente enfin les recherches liées à l'invention des enrobés à basses émissions et à température réduite, les enrobés bitumineux dits " semi-tièdes ", avec une évaluation des caractéristiques mécaniques et environnementales. La supervision de 23 stages étudiants (Ingénieurs et Mastères) et de 4 doctorants (Génie Civil) a rendu possible une bonne partie de ces travaux et résultats. L'ensemble du travail de recherche a donné lieu à 2 chapitres d'ouvrages scientifiques, 23 publications au sein de revues internationales à comité de lecture, 3 publications au sein de revues françaises à comité de lecture, 54 publications et présentations en conférences internationales, 30 publications de vulgarisation dans la littérature technique & professionnelle, ainsi que 3 brevets internationaux

Comportement thermomécanique des enrobés bitumineux à basses températures. Relations entre les propriétés du liant et de l\u27enrobé.

Cette thèse traite des relations entre les propriétés des liants et des enrobés bitumineux à basse température. Le comportement des bitumes fut évalué avec : i)l\u27essai de module complexe, ii)l\u27essai de fluage au BBR, iii)l\u27essai de traction SHRP à vitesse de déformation constante et températures constantes. Un essai de flexion trois points sur éprouvettes de bitume préentaillées a aussi été développé. Le comportement thermomécanique des enrobés fut étudié en réalisant i)des essais de module complexe, ii)des mesures du coefficient de contraction thermique, iii)des essais de traction à vitesses de déformation constantes, iv)des essais de retrait thermique empêché. Des liens pertinents entre les propriétés des liants et des enrobés, et des caractéristiques suffisamment discriminantes au regard des propriétés à basse température des enrobés ont été mis en évidence. Un travail de modélisation du comportement des liants et des enrobés a enfin été réalisé en petites et grandes déformations

Use of image analysis to predict the sound absorption coefficient of bituminous mixtures

International audienc

Calculation of Viscous Energy Dissipation in Asphalt Pavements

This paper presents a method to evaluate the energy dissipation in the pavement, induced by the viscous behaviour of bituminous constituents. The introduced method starts from the experimental characterization of each material and goes to the determination of stress and strain field, as well as viscous dissipated energy, in a pavement structure under a rolling wheel. A classical French pavement structure is considered as an application example. First, the behaviour of bituminous materials is characterized with advanced complex modulus tests. Second, a rheological model is used to describe the linear visco-elastic behaviour of bituminous materials. This model was previously developed at the Civil Engineering and Buildings Department of University of Lyon/ENTPE and has already shown its ability to describe completely and precisely the observed behaviour of bituminous materials. In order to make calculation the Finite Element software is then used in a third step, with the previous material model. Detailed hypotheses to perform the simulation of a rolling wheel on the pavement structure are explained. Results of the simulation are presented in terms of dissipated energy inside the pavement for a 40 ton truck. To give an order of magnitude, an estimation of the fuel consumption excess is given. Different temperature and vehicle speeds are considered. The Time Temperature Superposition Principle has been applied to estimate the dissipated energy at any temperature and vehicle speed. The simulation results show that energy dissipation in bituminous pavement due to the rolling weight of the considered 40 ton truck may induce a fuel consumption excess of a few percent for very unfavourable climatic conditions

Laboratory investigations on the Total Organic Compounds emissions of half-warm mix asphalt technology versus traditional hot mix asphalt

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

Viscoelastic Behaviour Characterization of a Gap-graded Asphalt Mixture with SBS Polymer Modified Bitumen

International audienc

Influence of the low-emission asphalt LEA® composition on total organic compounds emissions using the factorial experimental design approach

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 the 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 LEA® (acronym of low-emission and low-energy asphalt) produced at 95°C compared to the corresponding hot mix asphalt acting as a reference. 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

Prediction of LVE Behavior of Mixtures Containing RAP from Properties of Base Constituents

AbstractConsiderable research efforts are made to develop methods to predict mechanical behavior of bituminous mixtures from properties of basic components. In particular, such methods would be most useful for the design of mixtures containing Reclaimed Asphalt Pavement (RAP) material. The objective of the study is the simulation of Linear ViscoElastic (LVE) behavior of bituminous mixtures containing RAP from LVE properties of base constituents.Five mixtures were produced and tested, a reference mixture produced only with 35/50 binder, a mixture containing 100% RAP and three mixtures produced with 35/50 binder and different RAP contents (20%, 40% and 60%). All mixtures had the same granular size distribution curve. Complete LVE characterization was carried out on all materials. DSR and Tension/Compression (T/C) tests were performed on base and RAP-extracted binders (from -30 ̊C to +70 ̊C and from 0.01Hz to 30Hz). T/C tests were carried out on mixtures (from -25 ̊C to 40 ̊C and from 0.001Hz to 10Hz). Test results on both binders and mixtures were successfully fitted with 2S2P1D (2 Springs, 2 Parabolic elements, 1 Dashpot) model.LVE behavior of mixtures containing RAP was simulated by using as input data only LVE properties of base binders (35/50 and RAP-extracted binders) and of the reference mixture (produced with 35/50 binder, without RAP). In order to do this, two existing procedures, previously developed at the ENTPE, were used conjunctly. The first procedure was applied to predict LVE behavior of binder blends of pure base and RAP-extracted binders over the whole range of frequency and temperature. This procedure allows estimating 2S2P1D parameters of binder blends from those of base bitumens, according to their proportions in the blend. Therefore, LVE properties of blends can be predicted over the whole range of frequency and temperature. The second procedure used is SHStS (Shift, Homothety, Shift in time, Shift) transformation. This analytical tool is useful to determine the relationship between LVE behavior of mixtures and their corresponding binders. Experimental data of pure 35/50 binder and its corresponding mixture (without RAP) were used to calibrate SHStS transformation, depending mainly on aggregate skeleton. LVE behavior of mixtures produced with RAP was then estimated from simulations of LVE properties of blends, having the same proportions of base binders, obtained with the first procedure.Simulations of LVE behavior of mixtures containing RAP were finally compared to T/C test data. Successful correspondence was found between predicted and experimental results. Small discrepancies observed can be reasonably attributed to incomplete blending of base and RAP binders within the mixture. Therefore, as a first approximation, the proposed procedure can be used to predict LVE behavior of mixtures produced with RAP, over the whole range of frequency and temperature, from LVE properties of base binders and of a reference mixture (with the same granular size distribution) are known