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Oxidative aging is responsible for the irreversible asphalt stiffening and embrittlement leading to asphalt pavements of increased susceptibility to fatigue and thermal cracking. In recent years, various flexible binders have been introduced in asphalt industry to produce long-life pavements and the epoxy asphalt binders are among them. Nevertheless, in-depth understanding of the oxidative aging mechanism of epoxy asphalt binders and binding systems is still needed to enable reliable predictions of material degradation through service life. In this research, the compositional and rheological changes of epoxy asphalt, with and without filler, were analysed by means of Fourier Transform Infrared spectroscopy and Dynamic Shear Rheometer. Especially, kinetics (Arrhenius) parameters of epoxy asphalt have been determined by tracking the chemical composition changes. Oxidation of carbon species in epoxy asphalt is compositional dependent, and low values of activation energy accompany in low values of reaction rate are shown by adding epoxy in asphalt. Furthermore, the epoxy asphalt mastics (binders with filler) have been subjected to rheological testing to evaluate the stiffening effect as oxidation proceeds. Increase of modulus over a wide range of frequencies, decrease of frequency dependency of modulus of epoxy asphalt and shifting of phase angle to lower values are some important observations noticed as well. Overall, oxidation in epoxy asphalt materials occurs slowly yielding to oxygen-resistant binders when epoxy compounds are incorporated in asphalt binders. [ABSTRACT FROM AUTHOR]

The adhesive bonding strength of the membrane layers between the asphalt concrete surface layers and the decks of steel bridges has a strong influence on the fatigue life of orthotropic steel deck bridges (OSDBs). The interfacial properties between the membrane and the layers bonded to it have not been extensively studied in the current orthotropic steel deck bridge system. For the adequate characterisation of the adhesive-bonding strength of various membranes and surrounding materials on OSDBs and for the collection of the necessary parameters for finite element model, details of the membrane adhesion test (MAT) are introduced and simulated by using the adhesive traction-separation interface element which was developed in a companion paper to this contribution (Liu, X., Kasbergen, C., Li, J., & Scarpas, A. (2019). Modelling of membrane bonding response: part 1 development of an adhesive contact interface element. International Journal of Pavement Engineering). Parametric studies of the adhesive contact element utilised for modelling the membrane bonding layer in the MAT test have been performed on the basis of the combination of different critical strain energy release rates and the characteristic opening length in the constitutive model. Comparison of membrane deformation profiles and the in-time debonding force distribution between experimental observations and finite element simulations have been presented. [ABSTRACT FROM AUTHOR]

The adhesive bonding strength of the membrane layers between the asphalt concrete surface layers and the decks of steel bridges has a strong influence on the fatigue life of orthotropic steel deck bridges (OSDBs). The most important requirement for the application of membrane materials to orthotropic steel deck bridges is that the membrane adhesive layer is able to sufficiently bond to its surrounding material layers. The interfacial properties between the membrane and the layers bonded to it have not been extensively studied in the current orthotropic steel deck bridge system. In this paper, details of the contact interface element utilised to model the interfacial bonding properties will be discussed. Furthermore, the traction-separation material law will be chosen to describe the bonding response of the interfacial properties of the membrane to its surrounding surfacing layers on OSDBs. Some numerical examples, in which various aspects of the finite elements response of the contact interface model will be presented. Utilisation of the model in finite element analyses has enabled the investigation of the response of a 3D orthotropic steel deck bridge subjected to the different traffic loading conditions. [ABSTRACT FROM AUTHOR]

The orthotropic steel deck bridges (OSDBs) in the Netherlands consists mostly of multilayer system: top porous asphalt layer, guss asphalt layer, steel deck and two membrane layers. The five-point bending (5PB) beam test is the standard device in France for characterization of fatigue response of asphalt concrete surfacings used on orthotropic steel deck bridges. In this paper, an analytical solution for the 5PB beam test setup is presented first. In order to better understand the influence of geometrical, mechanical and structural parameters on the performance of the typical multilayer surfacing system of OSDBs, the 5PB test specimens with five structural layers have been investigated. The parametric study is performed at the numerical platform CAPA-3D that was developed at the Section of Structural Mechanics of TU Delft. The influences of the thickness of the asphalt layers and the mechanical properties of both top and bottom membrane layers are studied. The sensitivities of those influence factors are evaluated by the examination of the maximum tensile stress at the top surface of the porous asphalt layers and the strain distributions through the entire thickness of the specimen at two cross-sections. [ABSTRACT FROM AUTHOR]

Induction heating driven polymerisation is an in-situ curing technique for epoxy-asphalt systems that maintains most of the advantages of temperature-driven polymerisation and it solves the need for longer curing time periods at lower temperatures before traffic can be allowed. In particular, induction heating can be utilised to accelerate the polymerisation of paving mixes with a thermo-hardening nature. In this study, steel fibres are dispersed in a mix and during exposure to an alternating electro-magnetic field generated by induction coils, they are heated leading to the rapid initiation of epoxy-asphalt polymerisation. This research presents the implementation of a finite element model analysis for assessing the potential of utilising steel fibres for the development of inductive mixes with sufficient induction heating efficiency. A produced and compacted mix with steel fibres was reconstructed by means of CT scans on samples from the mix and its effective electrical conductivity was calculated. Also, the electro-magnetic induction-driven polymerisation of epoxy-asphalt is simulated by extending a model developed elsewhere. The extended method can be used to predict the evolution of the curing process, and further of mechanical properties thereby indicating that electro-magnetic induction represents a reliable polymerisation method to cure epoxy-asphalt systems. [ABSTRACT FROM AUTHOR]