An increase in environmental awareness and energy concerns had recently prompted efforts to make pavement construction cheaper and more environmentally friendly. Warm mix asphalt (WMA) is an asphalt mixture production technology that promises to reduce production costs and greenhouse gas emissions. Foamed asphalt binder is increasingly being used to produce WMA. This dissertation addresses several issues related to the use of foamed asphalt binder for WMA applications. The first objective of the research presented in this dissertation is to develop a method and metrics to precisely quantify the characteristics of asphalt binder foams. Laboratory measurements were obtained using the newly developed method to evaluate the extent and stability of foams produced using different asphalt binders at different water contents and laboratory foaming devices. Results demonstrate that the method developed is promising in terms of its ability to provide a detailed history of the behavior of foamed asphalt binder as the foam collapses. In addition, results indicate that the method is sensitive to distinguish between foaming characteristics of different asphalt binders as well as different water contents and foaming devices. The second objective of this study was to relate intrinsic properties of the asphalt binder to its foaming characteristics. A physical model was developed for expansion of asphalt binder foam based on foam physics and fluid mechanics of micro-droplets. The model relates foamant water and asphalt binder mixing efficiency with the surface tension of the asphalt binder. The model can be used to predict which binder can be effectively foamed and used, and whether any chemical modification to the binder is necessary to achieve the same. Results indicate that only a small percentage of water is effective in foaming the asphalt binder. The last objective of this research was to evaluate the influence of foaming on asphalt binder residues and mixture workability and coatability. The influence of foaming process on the rheological properties of asphalt binder residue was investigated. In addition, the significance of foamed asphalt binder characteristics on mixture workability and coatability was evaluated. Results from this last part of the study can be used to optimize binder foaming such that the resulting mixture is coated and compacted without compromising performance. / text

Constitués de plusieurs composants (granulats naturels et pâte de ciment adhérente), les GBR ne sont à l’heure actuelle pas utilisés largement dans la formulation de nouveaux bétons. Les propriétés médiocres des GBR compliquent considérablement la détermination de la quantité d’eau efficace dans le béton frais. Tout d’abord, une étude bibliographique va mettre en évidence la grande dispersion des résultats des essais de caractérisation des GBR et des propriétés des bétons recyclés à l’état frais et durci. Ensuite, une étude vise à analyser l’hétérogénéité des GBR et des granulats de béton concassé (GBC) par rapport à différents paramètres : aux impuretés granulaires, à la densité et à la teneur en pâte de ciment, au malaxage du béton parent, et au niveau de la capacité d’absorption d’eau des GBC en fonction de leur état de pré-humidification. Enfin, une dernière partie est destinée à améliorer la maîtrise de l’eau efficace réelle dans la fabrication du béton recyclé. La cinétique d’absorption des GBC dans une pâte de ciment est tout d’abord étudiée. Ensuite, l’évolution de l’eau efficace durant le malaxage de bétons à base de GBC est investiguée au moyen d’une méthode originale basée sur le suivi des courbes de puissance du malaxeur. Finalement, l’effet d’un malaxage sous vide relatif sur les propriétés des bétons à base de granulats naturels et des bétons à base de GBC est étudié. / Composed of several components (natural aggregates and adherent cement paste), RCA are not widely recommended in new concrete formulations. Their poor properties considerably complicate the determination of the effective water in fresh concrete. In a first part, a bibliographic study will highlight the wide dispersion of the results of characterization tests of RCA and the properties of fresh and hardened recycled concrete. In a second part, the heterogeneity of RCA and crushed concrete aggregates (CCA) is studied according to different parameters: granular impurities, density, cement paste content, mixing of parent concrete, and water absorption capacity according to their pre-humidification. The third part consists of three experimental studies that intend to improve effective water control in the manufacture of recycled concrete. The absorption kinetics of CCA in a cement paste is first studied. Then, the evolution of effective water in fresh concrete during mixing is studied using an original method based on the power evolution of the mixer. Finally, the effect of vacuum mixing on the properties of ordinary and recycled concretes is investigated.