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  • 1.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modèle viscoélastique-viscoplastique couplé avec endommagement pour les matériaux polymères semi-cristallins2012Manuscript (preprint) (Other academic)
  • 2.
    Balieu, Romain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Chen, Feng
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Life Cycle Sustainability Assessment of Electrified Road Systems2019In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed)
    Abstract [en]

    The widespread use of Electric Vehicles (EVs) has been one of the main directionsfor pursuing a sustainable future of road transport in which, the deployment ofthe associated charging infrastructures, static or dynamic, has been included as oneof the main cornerstones for its success. Different electrified road (eRoad) systemswhich allow for dynamic charging of EVs by transferring electrical power from theroad to the vehicle in-motion, either in a conductive or contactless way, are underactive investigation. One of the important tasks in feasibility analysis of suchinfrastructure is to quantitatively assess its environmental performance and, thus,the consequential influences to the sustainability of road electrification as a whole.Having this concern in mind, in this study, a systematic LCA study is carried out in which the environmental impacts from the different life cycle stages have beencalculated and compared among several promising eRoad systems. In a next step,suitable strategies can be accordingly made to minimize these impacts in a most effectiveway; and more importantly, the LCA results of this study can serve as one ofthe important bases for conducting a more comprehensive and objective evaluationof the potential environmental benefits EVs could bring.

  • 3.
    Balieu, Romain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Chen, Feng
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Córdoba, E.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Multiplicative viscoelastic-viscoplastic damage-healing model for asphalt-concrete materials2016In: RILEM Bookseries, Springer Netherlands , 2016, p. 235-240Conference paper (Refereed)
    Abstract [en]

    A viscoelastic-viscoplastic model based on a thermodynamic approach is developed under finite strain in this paper. By introducing a damage evolution, the proposed model is able to reproduce the behavior of Asphalt-Concrete materials until the complete fracture. Moreover, a recoverable part of the degradation is introduced to reproduce the self-healing observed under a sufficiently long rest period. The proposed model is implemented into a Finite Element code and good correlations between the numerical responses and the experiments have been observed. 

  • 4.
    Balieu, Romain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    A new thermodynamical framework for finite strain multiplicative elastoplasticity coupled to anisotropic damage2015In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 70, p. 126-150Article in journal (Refereed)
    Abstract [en]

    The thermodynamical framework of an elastoplastic model coupled to anisotropic damage is presented in this paper. In the finite strain context, the proposed model is based on the multiplicative decomposition of the strain gradient into elastic and plastic parts. The anisotropic degradation is introduced by means of a second order tensor and another intermediate configuration is introduced by fictitiously removing this degradation from the plastic intermediate configuration. To enhance the physical meaning of the Mandel-like stress measure work conjugated to the inelastic flow stated in this fictitious configuration, i.e. the "effective stress", a new damage rate tensor is defined with its associated push-forward and pull-back operations. The emphasis in this paper is placed on the description of the interesting properties of the novel definitions of the push-forward and pull-back operations which are discussed through a thermodynamical framework. Furthermore, a specific constitutive model with the plastic and damage flow rules deduced from the restrictions imposed by the second law of thermodynamics is discussed with an application on an asphalt concrete material where the anisotropic evolution of the damage is highlighted.

  • 5.
    Balieu, Romain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Lauro, F.
    Bennani, B.
    Haugou, G.
    Chaari, F.
    Matsumoto, T.
    Mottola, E.
    Damage at high strain rates in semi-crystalline polymers2015In: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 76, p. 1-8Article in journal (Refereed)
    Abstract [en]

    A specific damage characterization method using Digital Image Correlation for semi-crystalline polymers is proposed for a wide range of strain rates. This damage measurement is an extension of the SEE method [16] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials. This procedure is compared to the well-known damage characterization by loss of stiffness technique under quasi-static loading. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. The different ways used to evaluate the damage evolution are compared and the proposed technique is also suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading.

  • 6.
    Balieu, Romain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Lauro, F.
    Bennani, B.
    Matsumoto, T.
    Mottola, E.
    Non-associated viscoplasticity coupled with an integral-type nonlocal damage model for mineral filled semi-crystalline polymers2014In: Computers & structures, ISSN 0045-7949, E-ISSN 1879-2243, Vol. 134, p. 18-31Article in journal (Refereed)
    Abstract [en]

    A non-associated viscoplastic model coupled with nonlocal damage under finite strain framework is developed to simulate the non-isochoric deformation and the damage process exhibiting strain-softening of a 20% mineral filled semi-crystalline polymer. The logarithmic spin tensor properties linking the Eulerian Hencky strain with the Cauchy stress is used thanks to hypoelasticity assuming the additive decomposition of the stretching into elastic and viscoplastic parts. The constitutive model with its nonlocal formulation is implemented in an efficient manner in a commercial implicit finite element code. The proposed model exhibits mesh-independent responses and is in agreement with strain evolution observed experimentally.

  • 7.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Cordoba, Enrique
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Towards an understanding of the structural performance of future electrified roads: a finite element simulation study2018In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 20, no 2, p. 204-215Article in journal (Refereed)
    Abstract [en]

    Nowadays, many novel technologies are under investigations for making our road infrastructure functionbeyond providing mobility and embrace other features that can promote the sustainability developmentof road transport sector. These new roads are often referred to as multifunctional or ‘smart’ roads. Focusin this paper is given to the structural aspects of a particular smart road solution called electrified road or‘eRoad’, which is based on enabling the inductive power transfer technology to charge electric vehiclesdynamically. Specifically, a new mechanistic-based methodology is firstly presented, using a finiteelement simulation and an advanced constitutive model for the asphalt concrete materials. Based onthis, the mechanical responses of a potential eRoad structure under typical traffic loading conditions arepredicted and analysed thoroughly. The main contributions of this paper include thus: (1) introducing anew methodology for analysing a pavement structure purely based on mechanistic principles; (2) utilisingthis methodology for the investigation of a future multifunctional road pavement structure, such as aneRoad; and (3) providing some practical guidance for an eRoad pavement design and the implementationinto practice.

  • 8.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Potential Influences on Long-Term Service Performance of Road Infrastructure by Automated Vehicles2016In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2550, p. 72-79Article in journal (Refereed)
    Abstract [en]

    Automated vehicles (AVs) have received great attention in recent years, and an automated road transportation sector may become reality in the next decades. Many benefits of AVs have been optimistically predicted, although some benefits may be overestimated because of a lack of thinking from a holistic point of view. From a future perspective, this study investigated the potential consequences to the long-term service performance of practical physical road infrastructure after the advent of the implementation of AVs on a large scale. Specifically, the, pavement rutting performance by the possibly changed behaviors, such as the vehicle's wheel wander, lane capacity, and traffic speed, was examined carefully with the finite element modeling approach. With the use of AVs, the decreased wheel wander and increased lane capacity could bring an accelerated rutting potential, but the increase in traffic speed would negate this effect, which was shown by the simulation results of rut depth. Therefore the influence cannot be judged as positive or negative in general; judgment actually depends much on the practical road and traffic conditions. In the future the physical roads not only might serve for the mobility of the vehicles but also might be capable of enabling other new functions. An early consideration of how to lead the future development of physical road infrastructure toward multifunctionality is emphasized.

  • 9.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Sustainable implementation of future smart road solutions: a case study on the electrified road2017In: Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017) / [ed] Andreas Loizos, Imad Al-Qadi, Tom Scarpas, Athens, Greece: CRC Press, 2017Conference paper (Refereed)
    Abstract [en]

    An important feature of a future smart or multifunctional road is that an intrinsic integration of different new advances into the practical roads should be achieved, in terms of such as Car-to-Road communication, energy harvesting, autonomous driving or on-the-road charging. However, our current engineering and research communities do not necessarily allow for an optimal development of such integrated systems. To fill some of the knowledge gaps from infrastructure point of view, this research is focusing on a specific case of the electrified road (also called ‘eRoad’) that allows for on-the-road charging, in which the consequences and possible modifications of the road infrastructure are considered. Some preliminary analysis results are presented in this paper, from which it has been found that such kind of the integration could indeed influence the service performance of individual components of the whole system, while further studies should be carried out to ensure the implementation of these smart technologies is ultimately sustainable.

  • 10.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Thermodynamics-based finite strain viscoelastic-viscoplastic model coupled with damage for asphalt material2017In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 129, p. 61-73Article in journal (Refereed)
    Abstract [en]

    A thermodynamics based thermo-viscoelastic-viscoplastic model coupled with damage using the finite strain framework suitable for asphalt material is proposed in this paper. A detailed procedure for model calibration and validation is presented, utilizing a set of experimental measurements such as creep recovery, constant creep, and repeated creep-recovery tests under different loading conditions. The calibrated constitutive model is able to predict the sophisticated time- and temperature-dependent responses of asphalt material, both in tension and in compression. Moreover, a scenario case study on permanent deformation (rutting) prediction of a practical asphalt pavement structure is presented in this work. This paper presents the main features of this new constitutive model for asphalt: (1) A thermodynamics-based framework developed in the large strain context to derive the specific viscoelastic, viscoplastic and damage constitutive equations; (2) A viscoelastic dissipation potential involving deviatoric and volumetric parts, in which Prony series representations of the Lame constants are used; (3) A modified Perzyna's type viscoplastic formulation with non-associated flow rule adopted to simulate the inelastic deformation, using a Drucker-Prager type plastic dissipation potential; (4) A specific damage model developed for capturing the evolution disparity between tension and compression. As such, the developed model presents a robust, fully coupled and validated constitutive framework that includes the major behavioral components of asphalt materials, enabling thus an optimized simulation of predicted performance under various conditions. Further development improvements to the model in continued research efforts can be to include further environmental and physico-chemical material behavior such as ageing, healing or moisture induced damage.

  • 11.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Thermodynamics-based finite strain viscoelastic-viscoplastic model coupled with damage for asphalt materialArticle in journal (Other academic)
    Abstract [en]

    A thermodynamics based thermo-viscoelastic-viscoplastic model coupled with damage using the finite strain frameworksuitable for asphalt material is proposed in this paper. A detailed procedure for model calibration and validationis presented, utilizing a set of experimental measurements such as creep-recovery, constant creep, and repeated creeprecoverytests under dierent loading conditions. The calibrated constitutive model is able to predict the sophisticatedtime- and temperature- dependent responses of asphalt material, both in tension and in compression. Moreover, a scenariocase study on permanent deformation (rutting) prediction of a practical asphalt pavement structure is presentedin this work. This paper presents the main features of this new constitutive model for asphalt: 1) A thermodynamicsbasedframework developed in the large strain context to derive the specific viscoelastic, viscoplastic and damageconstitutive equations; 2) A viscoelastic dissipation potential involving deviatoric and volumetric parts, in whichProny series representations of the Lam´e constants are used; 3) A modified Perzyna’s type viscoplastic formulationwith non-associated flow rule adopted to simulate the inelastic deformation, using a Drucker-Prager type plastic dissipationpotential; 4) A specific damage model developed for capturing the evolution disparity between tension andcompression. As such, the developed model presents a robust, fully coupled and validated constitutive framework thatincludes the major behavioral components of asphalt materials, enabling thus an optimized simulation of predictedperformance under various conditions. Further development improvements to the model in continued research eortscan be to include further environmental and physico-chemical material behavior such as ageing, healing or moistureinduced damage.

  • 12.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Coronado, Carlos F.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Structural performance of electrified roads: A computational analysis2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 195, p. 1338-1349Article in journal (Refereed)
    Abstract [en]

    Given its promise for enhanced sustainability, electrified road (eRoad) has become a realistic option to support the clean and energy efficient Electrical Vehicles (EVs). To investigate the structural implications, this study focuses on a promising eRoad system which is a dynamic application of the Inductive Power Transfer (IPT) to provide electrical power wirelessly to EVs in-motion. A computational study is made in which, via a series of Finite Element Modeling (FEM) analyses on the eRoad structural response under various rolling conditions, is found that eRoads could have quite different pavement performances comparing to the traditional road (tRoad). Importantly, harsh loading due to vehicle braking or accelerating could incur higher potential of premature damage to the structure, whereas sufficient bonding at the contact interfaces would improve the structural integrity and delay the damage risks. In addition, localized mechanical discontinuities could also be a critical threat to the performance of the overall structure. To ensure that eRoads fulfill their sustainability promise, it is thus recommended that more focus should be placed on the possible measures, such as new structures and materials, to improve the structural integrity and thus the overall pavement performance of the integrated system.

  • 13.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Dynamic application of the Inductive Power Transfer (IPT) systems in an electrified road: Dielectric power loss due to pavement materials2017In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 147, p. 9-16Article in journal (Refereed)
    Abstract [en]

    Inductive Power Transfer (IPT) technology is seen as a promising solution to be applied in an electrified road (eRoad) to charge Electric Vehicles (EVs) dynamically, i.e. while they are in motion. Focus in this study was placed on the dielectric loss effect of pavement surfacing materials on the inductive power transfer efficiency, induced after the integration of the technology into the physical road structure. A combined experimental and model prediction analysis was carried out to calculate this dielectric loss magnitude, based on which some preliminary conclusions as well as a prioritization of future focus needs were summarized in detail.

  • 14.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    On the Oxidative Ageing Mechanism and Its Effect on Asphalt Mixtures Morphology2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 15, p. 3113-3127Article in journal (Refereed)
    Abstract [en]

    This paper investigates the influence of mixture morphologies and microstructures on oxidative ageing of asphalt mixtures. For this, an oxidative ageing mechanism based on a diffusion–reaction process was developed. Previously, most asphalt oxidative ageing modeling research focused on unidirectional diffusion of continuous oxygen flow through bitumen films, which is far from the actual boundary conditions in asphalt mixtures. For this reason in the current study, a finite element (FE) analysis has been conducted in which 3D mixture morphology was considered. Mixture morphology is the combination of mineral aggregate packing, porosity, air-void distribution and their interconnectivity. One dense and one open graded field asphalt mixture core were scanned with a computerized tomography X-ray scanner. In the analyses, the developed oxidative ageing model was implemented. The FE analysis showed that the effect of the air-void distribution, their interconnectivity and the mineral aggregate packing has a significant effect on the resulting age hardening of the overall mixture. Furthermore, from the microstructural investigation done in this research, strong indications were found that, depending on the bitumen and its conditioning, water soluble thin films are formed due to ageing. This means that ageing and moisture damage are strongly interlinked and this should thus be considered in the design of the asphaltic materials and the prediction of their long term performance. © 2014, RILEM.

  • 15.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modelling coalescence process during breaking of bitumen emulsions2016In: / [ed] International Society for Asphalt Pavements (ISAP), 2016, p. 1-12, article id Paper 61Conference paper (Refereed)
    Abstract [en]

    Cold mix bitumen emulsion technology is getting a lot of focus by the road industries since a few decades due to the diminished environmental impacts and reduced energy associated with it. The durability and mechanical performance of cold asphalt mixtures very much depend on the breaking, coalescence and phase separation processes in bitumen emulsions; however, the exact nature of the breaking mechanism of bitumen emulsion is not completely understood today. During coalescence or relaxation process, two bitumen droplets are completely fused into a unique spherical droplet and their kinetic is usually recorded in terms of time, denoted as relaxation time or τrelaxation.  In this work, a two dimensional Phase Field model was used to simulate the coalescence process of two bitumen droplets in water phase. The numerical model is based on Finite Element Method and solves Navier-Stokes system of equations coupled with the Cahn-Hilliard equation. The model predictions are validated by direct comparison with the experimental measurements performed in our previous work. Moreover, the study was extended to the small size (order μm) bitumen droplets which are difficult to produce and handle via experimental methods.  

  • 16. Lauro, Franck
    et al.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE).
    Bennani, Bruno
    Haugou, Gregory
    Bourel, Benjamin
    Chaari, Fahmi
    Matsumoto, Tsukatada
    Mottola, Ernesto
    Damage characterization for particles filled semi-crystalline polymer2015In: DYMAT 2015 - 11Th International Conference on The Mechanical And Physical Behaviour of Materials Under Dynamic Loading, EDP Sciences, 2015, Vol. 94, p. 01009-, article id 01009Conference paper (Refereed)
    Abstract [en]

    Damage evolution and characterization in semi-crystalline polymer filled with particles under various loadings is still a challenge. A specific damage characterization method using Digital Image Correlation is proposed for a wide range of strain rates considering tensile tests with hydraulic jacks as well as Hopkinson's bars. This damage measurement is obtained by using and adapting the SEE method [1] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials in dynamic. To validate the characterization process, various damage measurement techniques are used under quasi-static conditions before to apply the procedure in dynamic. So, the well-known damage characterization by loss of stiffness technique under quasi-static loading is applied to a polypropylene. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. A good correlation is obtained between all these techniques and consequently the proposed technique is supposed suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading. By applying it to the semi-crystalline polymer at moderate and high speed loadings, the damage evolution is measured and it is observed that the damage evolution is not strain rate dependent but the failure strain on the contrary is strain rate dependent.

  • 17.
    Ledesma, Enrique Córdoba
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Chen, Feng
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Towards an understanding of the structural integrity of electrified roads through a combined numerical and experimental approach2017In: TRB 96th Annual Meeting Compendium of Papers, 2017Conference paper (Refereed)
    Abstract [en]

    The continuous growth in road transportation demands further development towards sustainable strategies. The electrification of road infrastructure (commonly referred to as ‘e-Road’) to enable wireless charging solutions for Electric Vehicles (EVs) is arising as one of the most promising and yet challenging alternatives for the future mobility by road. In this context, the introduction of charging facilities in the pavement structure and its adequate performance from an infrastructural perspective is determining for the successful implementation of these systems.This study aims to evaluate the structural integrity of e-Roads, considering the embedment in the pavement of a solid module denominated ‘Charging Unit’ (CU) in which the charging facilities are assumed to be installed. To do so, the critical locations of an e-Road pavement structure were identified through computational modelling for its further representation as small-scale e-Road samples in the laboratory. Afterwards, this structure was subjected to different loading conditions using mechanical hydraulic devices and compared with conventional road samples produced under the same conditions. Finally, e-Road samples were scanned with X-ray Computed Tomography (CT) prior to, during and after loading for additional inspection. Results provided valuable learnings of the potential mechanisms of failure of such structure and a better understanding of the e-Road infrastructure. 

  • 18.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A Coupled Micromechanical Model of Frost Damage in Asphalt2018In: Transportation Research Board 97th Annual Meeting, Washington DC, January 7-11, 2018, 2018Conference paper (Refereed)
    Abstract [en]

    Frost damage in asphalt pavements is an important factor influencing the performance of the pavement. This type of damage occurs during freeze-thaw cycles when ice forms in the air voids, causing microstructural changes and degradation of material properties, thus affecting the performance of the pavement. It is therefore necessary to understand the process of frost damage in order to prevent it. However, experimental testing is often expensive and time consuming and only a limited number of numerical models dealing with the topic exist. In this work, a numerical micromechanical model has been developed that couple the diffusion of moisture in the asphalt to the damage occurring in a freezing and thawing environment. In this paper, the model is presented and applied on an asphalt microstructure obtained by x-ray scanning of a real asphalt sample. The effect of including frost damage is shown by comparing the behavior of a damaged microstructure to the behavior of an undamaged microstructure. It is revealed that the strength of the damaged microstructure reduces to about 50% of the strength of the undamaged microstructure. Furthermore, the coupling of the moisture content in the air voids to the expansion of the air voids is proved to be important since the assumption that all air voids are fully saturated overestimates the decrease in strength. The next step in this research will be to validate the model with laboratory data. A validated model can assist in improving the predictions of frost damage and help in developing better laboratory tests.

  • 19.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A micromechanical model of freeze-thaw damage in asphalt mixturesIn: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed)
    Abstract [en]

    Freeze-thaw damage in asphalt pavements is a complex phenomenon depending on many parameters such as moisture infiltration, temperature and mechanical properties of the asphalt constituents as well as the interface between them. As a first step in creating a comprehensive multiscale model including all of these parameters, a micromechanical model has been developed. This model couples the infiltration of moisture and the associated damage, the expansion caused by the water inside the air voids freezing, and the mechanical damage. The expansion of the air voids is implemented by applying a volumetric expansion in the air voids dependent on the temperature. The cohesive damage in the mastic and adhesive damage in the mastic-aggregate interface are included by implementing an energy based damage model and the cohesive zone model, respectively. To show the capabilities of the model, two different graded microstructures were exposed to 10 freeze-thaw cycles each and their stiffness was evaluated before and after the simulated freeze-thaw cycles. In addition, the sensitivity of the resulting damage to the time the microstructure was exposed to temperatures below zero was evaluated by simulating freeze-thaw cycles with a total time ranging between 10 hours and 14 days. From the analyses it was concluded that the model was capable of capturing the deteriorating effect of an increasing number of freeze-thaw cycles, and was sensitive to the freezing time in the freeze-thaw cycles.    

  • 20.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A micromechanical model of freeze-thaw damage in asphalt mixtures2019In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed)
    Abstract [en]

    Freeze-thaw damage in asphalt pavements is a complex phenomenon dependent on many parameters such as moisture infiltration, temperature and mechanical properties of the asphalt constituents as well as the interface between them. As a first step in creating a comprehensive multiscale model including all of these parameters, a micromechanical model has been developed. This model couples the infiltration of moisture and the associated damage, the expansion caused by the water inside the air voids freezing, and the mechanical damage. The expansion of the air voids is implemented by applying a volumetric expansion in the air voids dependent on the temperature. The cohesive damage in the mastic and adhesive damage in the mastic-aggregate interface are included by implementing an energy-based damage model and the cohesive zone model, respectively. To show the capabilities of the model, the effect of different parameters (the number of freeze-thaw cycles, the gradation of the microstructure, and the freezing time) was investigated through simulations. From the analyses it was concluded that the model was capable of capturing the deteriorating effect of an increasing number of freeze-thaw cycles, and was sensitive to the freezing time in the freeze-thaw cycles.

  • 21.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Freeze-thaw damage in asphalt: a set of simplified simulations2018In: Proceedings of Canadian Technical Asphalt Association 63rd Annual Conference / [ed] Stephen Goodman, 2018Conference paper (Refereed)
    Abstract [en]

    Winter damage in pavements, such as potholes, dislodging of stones and structural layer separation, occurs during and after winter seasons. This damage is caused by several processes, such as freezing and thawing action, moisture accumulation, traffic loads and winter maintenance actions, which combined makes winter damage a highly complex phenomenon. To better understand this process and, in the future, being able to predict the damage propagation by modeling, this paper discusses the possibility to separate these actions and phenomena into different cases. The focus in this paper is on the freezing -and thawing damage and how it is affected by different environmental conditions, inspired by real weather data from the City of Luleå in the north of Sweden. To investigate this, a microscale model is utilized. The results from the simulations show an increasing adhesive damage with the number of freeze-thaw cycles while the cohesive damage in the viscoelastic mastic increases is the most severe for a period with several days of freezing temperatures. A discussion of how the separation of winter damage into different cases will contribute to the ultimate goal of a multiscale model is also included.

  • 22.
    Lövqvist, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modeling the evolution of winter damage in an asphalt concrete microstructure2019Conference paper (Refereed)
    Abstract [en]

    Winter damage in asphalt pavements is a complex phenomenon which may cause pothole formation, dislodging of stones and structural layer separation. In order to reduce the winter damage, knowledge about the process in both the pavement and on a microstructural level is required. This paper focuses on modeling the process of damage evolution on a microstructural level in order to identify and understand the different phenomena influencing the degradation process. In this paper the evolution of winter damage in an asphalt concrete microstructure was modeled throughout the course of two winter seasons. The simulations include freezing and thawing cycles as well as additional damage originating from snow plows, both based on real weather data from Luleå in the north of Sweden. The results show a large increase of damage in both the mastic and the aggregate-mastic interface, and thereby also vertical displacement of the top surface, after the first freeze-thaw cycle. During the following freeze-thaw cycles the mastic damage continuous to increase but with a decreasing rate while the damage in the aggregate-mastic interface is only affected by the manually added damage from the snow plow. These results indicate a need to include the growth of -and emergence of new air voids in the model as well as an investigation of the actual behavior and influence of the damage evolution in the interface regions.

  • 23.
    Onifade, Ibrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Birgisson, B.
    Interpretation of the Superpave IDT strength test using a viscoelastic-damage constitutive model2016In: Mechanics of time-dependant materials, ISSN 1385-2000, E-ISSN 1573-2738, p. 1-19Article in journal (Refereed)
    Abstract [en]

    This paper presents a new interpretation for the Superpave IDT strength test based on a viscoelastic-damage framework. The framework is based on continuum damage mechanics and the thermodynamics of irreversible processes with an anisotropic damage representation. The new approach introduces considerations for the viscoelastic effects and the damage accumulation that accompanies the fracture process in the interpretation of the Superpave IDT strength test for the identification of the Dissipated Creep Strain Energy (DCSE) limit from the test result. The viscoelastic model is implemented in a Finite Element Method (FEM) program for the simulation of the Superpave IDT strength test. The DCSE values obtained using the new approach is compared with the values obtained using the conventional approach to evaluate the validity of the assumptions made in the conventional interpretation of the test results. The result shows that the conventional approach over-estimates the DCSE value with increasing estimation error at higher deformation rates.

  • 24.
    Onifade, Ibrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Birgisson, Björn
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Energy-Based Damage and Fracture Framework for Viscoelastic Asphalt Concrete2015In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 145, p. 67-85Article in journal (Refereed)
    Abstract [en]

    A framework based on the continuum damage mechanics and thermodynamics of irreversible processes using internal state variables is used to characterize the distributed damage in viscoelastic asphalt materials in the form of micro-crack initiation and accumulation. At low temperatures and high deformation rates, micro-cracking is considered as the source of nonlinearity and thus the cause of deviation from linear viscoelastic response. Using a non-associated damage evolution law, the proposed model shows the ability to describe the temperature-dependent processes of micro-crack initiation, evolution and macro-crack formation with good comparison to the material response in the Superpave indirect tensile (IDT) strength test.

  • 25.
    Zhu, Jiqing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lu, Xiaohu
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Microstructure evaluation of polymer-modified bitumen by image analysis using two-dimensional fast Fourier transform2018In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 137, p. 164-175Article in journal (Refereed)
    Abstract [en]

    Aiming to quantitatively evaluate the microstructure of polymer-modified bitumen (PMB) for roads, this paper employs the two-dimensional fast Fourier transform(2D-FFT) to process the microscopic and numerical images of four PMBs. The related derivative parameters, including the characteristic frequency and wavelength, are computed from the 2D-FFT power spectrum. The results show that the absence/presence of a characteristic frequency (range) on the power spectrum can indicate the lack/existence of the corresponding periodical structural pattern(s) in the original PMB image. A lower characteristic frequency usually represents a coarser PMB microstructure while a higher one implies a finer PMB microstructure. The 2D-FFT method is thus valid for differentiating various PMB microstructures. The proposed method is also capable of quantitatively evaluating the effects of temperature and the temporal evolution of PMB microstructure during phase separation. As the separation continues, the decrease of characteristic frequency indicates the coarsening process of a PMB microstructure. Additionally, the numerical reproduction of the observed phase separation is evaluated with the same method. The quantitative comparison with the experimental results reveals that the simulations fairly reproduced the microscopy observation results despite some deviation. The proposed method provides a foundation for the microstructure-based modelling of PMB performance in the future.

  • 26.
    Zhu, Jiqing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lu, Xiaohu
    Nynas AB.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Numerical investigation on phase separation in polymer modified bitumen: Effect of thermal condition2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 11, p. 6525-6541Article in journal (Refereed)
    Abstract [en]

    With the aim to understand the effect of thermal condition on phase separation in polymer-modified bitumen (PMB), this paper numerically investigates four PMB binders under five thermal conditions between 140 and 180 °C. Based on a phase-field model previously developed by the authors for PMB phase separation, the updated model presented in this paper uses temperature-dependent parameters in order to approach the concerned temperature range, including mobility coefficients, interaction and dilution parameters. The model is implemented in a finite element software package and calibrated with the experimental observations of the four PMBs. The experimental results are well reproduced by the model, and it is thus believed that the calibrated parameters can represent the four PMBs. The simulation results indicate that the model proposed in this paper is capable of capturing the stability differences among the four PMBs and their distinct microstructures at different temperatures. Due to the transition of some PMBs from the thermodynamically stable state at 180 °C to the unstable state at 140 °C, a homogenization process may occur during the cooling applied numerically. After the transition, the PMBs start to separate into two phases and gradually form the binary structures controlled by the temperature. It is indicated that the cooling rate slightly affects the final pattern of the PMB binary microstructure, although the process can be more complicated in reality due to the potential dynamic reasons.

  • 27.
    Zhu, Jiqing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lu, Xiaohu
    Nynas AB.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Numerical Prediction of Storage Stability of Polymer-Modified Bitumen: A Coupled Model of Gravity-Driven Flow and Diffusion2017In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, Vol. 2632, p. 70-78Article in journal (Refereed)
    Abstract [en]

    A coupled diffusion–flow model by phase-field method is proposed in this paper with the goal of predicting the storage stability of polymer-modified bitumen (PMB). In this study, the incompressible Navier–Stokes equations were coupled with a previously developed phase-field model for PMB phase separation. The coupled model was implemented in a finite element software package with experimentally calibrated parameters and reported data in the literature. Effects of the parameters (bitumen density and dynamic viscosity) that affected the gravity-driven flow and phase separation in PMB were evaluated at 180°C with the simulation results. The results indicate that the coupled diffusion–flow model can predict the storage stability (and instability) of PMBs. A good correlation between the simulation results and the previously reported experimental results (storage stability tube test) was observed. The different gravity-driven phase separation behaviors of PMBs might have resulted from the different composition of the equilibrium phases in the PMBs as well as the different densities and dynamic viscosities of the individual components (polymer and bitumen). A bigger polymer–bitumen density difference, a lower bitumen dynamic viscosity, or both caused a faster flow and separation in the PMB at storage temperature. The investigated variation of bitumen dynamic viscosity had a more significant influence than the investigated variation of bitumen density in this study, but this finding might depend on the specific values of the model parameters. With this study as a foundation, further experimental and numerical studies will be conducted to increase understanding of storage-stable PMB binders and to develop a more efficient test method for determining PMB storage stability.

  • 28.
    Zhu, Jiqing
    et al.
    Swedish Natl Rd & Transport Res Inst VTI, Linkoping, Sweden..
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Wang, Haopeng
    Delft Univ Technol, Fac Civil Engn & Geosci, Sect Pavement Engn, Delft, Netherlands..
    The use of solubility parameters and free energy theory for phase behaviour of polymer-modified bitumen: a review2019In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed)
    Abstract [en]

    Advances related to the use of solubility parameters and free energy theory for the phase behaviour study of polymer-modified bitumen (PMB) are reviewed in this paper. The origin and effects of PMB phase behaviour are criticised with a focus on PMB storage stability, morphology and swelling ratio. An overview of the solubility approach for studying PMB is given regarding the historical and future developments. Free energy expressions for PMB systems are analysed, including the free energy of mixing, elastic free energy and gradient energy. The kinetic aspects are discussed with respect to the diffusion and flow processes. It is indicated that the solubility bodies in the three-dimensional Hansen space and their degree of intersection can be useful for analysing the PMB thermodynamic equilibrium and thus storage stability. But they give no indication by themselves on the PMB morphology. With solubility parameters linked to the PMB free energy, however, an integrated thermodynamic approach can assist in understanding both PMB storage stability and morphology comprehensively. Due to the chemical complexity of bitumen and certain modifiers, the solubility body centres and radiuses should be both considered for a proper expression of the polymer-bitumen interaction in PMB. A hypothetical dilution process can simplify this process, but with limitations. The introduction of elastic free energy may lead to a new and more realistic expression of free energy for PMB system. With this overview, it is expected that a preliminary foundation is established towards a comprehensive and realistic thermodynamic framework for interpreting and predicting PMB phase behaviour.

  • 29.
    Zhu, Jiqing
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Lu, Xiaohu
    Nynas AB.
    Balieu, Romain
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modelling and numerical simulation of phase separation in polymer modified bitumen by phase-field method2016In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 107, p. 322-332Article in journal (Refereed)
    Abstract [en]

    In this paper, a phase-field model with viscoelastic effects is developed for polymer modified bitumen (PMB) with the aim to describe and predict the PMB storage stability and phase separation behaviour. The viscoelastic effects due to dynamic asymmetry between bitumen and polymer are represented in the model by introducing a composition-dependent mobility coefficient. A double-well potential for PMB system is proposed on the basis of the Flory-Huggins free energy of mixing, with some simplifying assumptions made to take into account the complex chemical composition of bitumen. The model has been implemented in a finite element software package for pseudo-binary PMBs and calibrated with experimental observations of three different PMBs. Parametric studies have been conducted. Simulation results indicate that all the investigated model parameters, including the mobility and gradient energy coefficients, interaction and dilution parameters, have specific effects on the phase separation process of an unstable PMB. In addition to the unstable cases, the model can also describe and predict stable PMBs. Moreover, the phase inversion phenomenon with increasing polymer content in PMBs is also well reproduced by the model. This model can be the foundation of an applicable numerical tool for prediction of PMB storage stability and phase separation behaviour.

1 - 29 of 29
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