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  • 1.
    Baldo, N
    et al.
    University of Padova, Padova, Italy.
    Pasetto, M
    University of Padova, Padova, Italy.
    Kringos, Nicole
    Delft University of Technology, Delft, The Netherlands.
    Kasbergen, C.
    Delft University of Technology, Delft, The Netherlands.
    Scarpas, A.
    Delft University of Technology, Delft, The Netherlands.
    Calibration and Validation of a Visco-Elasto-Plastic Constitutive Model for Bituminous Conglomerates2009In: ADVANCED TESTING AND CHARACTERISATION OF BITUMINOUS MATERIALS, Rhodes, Greece, 2009, p. 879-888Conference paper (Refereed)
    Abstract [en]

    The paper presents and discusses the calibration and validation of a three-dimensional constitutive visco-elasto-plastic model developed for the analysis of the mechanical behaviour of bituminous mixes. The methodology, an inverse problem technique, uses a one-dimensional analytic formulation of the constitutive model and four different algorithms of non-linear constrained optimisation: the Conjugate Gradient, Montecarlo, Davidon-Fletcher-Powell and Simplex. On the basis of the creep recovery data obtained from an experiment in support of the model calibration, it was verified that the values of the constitutive parameters can be reliably identified, even starting from different initial guesses. A subsequent comparison between the experimental creep curves and numerical ones of the 3-D model demonstrated minimal shifts, confirming the robustness of the identification procedure for the parameters.

  • 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.
    Butt, Ali Azhar
    et al.
    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.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Considering the benefits of asphalt modification using a new technical LCA framework2016In: Journal of Civil Engineering and Management, ISSN 1392-3730, E-ISSN 1822-3605, Vol. 22, no 5, p. 597-607Article in journal (Refereed)
    Abstract [en]

    Asphalt mixtures properties can be enhanced by modifying it with additives. Even though the immediatebenefits of using polymers and waxes to modify the binder properties are rather well documented, the effects of suchmodification over the lifetime of a road are seldom considered. To investigate this, a newly developed open technical lifecycle assessment (LCA) framework was used to determine production energy and emission limits for the asphaltadditives. The LCA framework is coupled to a calibrated mechanics based computational framework that predicts the intimepavement performance. Limits for production energy of wax and polymers were determined for the hypotheticalcase studies to show how LCA tools can assist the additives manufacturers to modify their production procedures andhelp road authorities in setting ‘green’ limits to get a real benefit from the additives over the lifetime of a road. From thedetailed case-studies, it was concluded that better understanding of materials will lead to enhanced pavement design andcould help in the overall reduction of energy usage and emissions.

  • 6.
    Butt, Ali Azhar
    et al.
    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.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Optimizing the Highway Lifetime by Improving the Self Healing Capacity of Asphalt2012In: Transport Research Arena 2012, 2012, Vol. 48, p. 2190-2200Conference paper (Refereed)
    Abstract [en]

    It is of imminent urgency to optimize the lifetime of asphalt binders from the remaining available crude sources. This paper presents a recently developed model in which the self-healing capacity of bitumen is based on fundamental chemo-mechanical parameters. The implications of the enhanced bitumen healing rates are investigated by utilizing a newly developed Open Life Cycle Assessment framework. From the case study it was concluded that using bitumen with self-healing capacity can lead to a significant reduction in Greenhouse Gas emission and energy usage. Additionally, the importance of knowing the fuels and emission of bitumen modifiers on the highway sustainability was demonstrated.

  • 7.
    Butt, Ali Azhar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    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.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Using Life Cycle Assessment to Optimize Pavement Crack-Mitigation2012In: Scarpas et al. (Eds.), 7th RILEM International Conference on Cracking in Pavements: Vol. 1, Delft, The Netherlands, 2012, p. 299-306Conference paper (Refereed)
    Abstract [en]

    Cracking is very common in areas having large variations in the daily temperatures and can cause large discomfort to the users. To improve the binder properties against cracking and rutting, researchers have studied for many years the behaviour of different binder additives such as polymers. It is quite complex, however, to decide on the benefits of a more expensive solution without looking at the long term performance. Life cycle assessment (LCA) studies can help to develop this long term perspective, linking performance to minimizing the overall energy consumption, use of resources and emissions. To demonstrate this, LCA of an unmodified and polymer modified asphalt pavement using a newly developed open LCA framework has been performed. It is shown how polymer modification for improved performance affects the energy consumption and emissions during the life cycle of a road. Furthermore, it is concluded that better understanding of the binder would lead to better optimized pavement design, hence reducing the energy consumption and emissions. A limit in terms of energy and emissions for the production of the polymer was also found which could help the polymer producers to improve their manufacturing processes, making them efficient enough to be beneficial from a pavement life cycle point of view.

  • 8.
    Butt, Ali Azhar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    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.
    Importance of systems approach for evaluating the life cycle environmental costs of a road projectManuscript (preprint) (Other academic)
  • 9.
    Butt, Ali Azhar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    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.
    Importance of systems approach for evaluating the life cycle environmental impacts of a road projectManuscript (preprint) (Other academic)
    Abstract [en]

    Aggregates from two different sources and the effect of using a warm mix asphalt additive(WMAA) in asphalt mixtures were investigated in the laboratory. Different pavement designalternatives were generated using the laboratory data and analysed using a road life cycleassessment (LCA) framework. It was concluded that the effects of WMAAs must beevaluated on a case by case basis since WMAA interaction with the aggregate surfacemineralogy appears to play a significant role. Asphalt production and material transportationwere found to be the most energy consuming processes having high greenhouse gasemissions. The results presented also showed that having actual pavement material propertiesas the key attributes in LCA enables a pavement focused assessment of environmental costsassociated with different design options.

  • 10.
    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.

  • 11.
    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.

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    Chen, Feng
    et al.
    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.
    Towards new infrastructure materials for on-the-road charging: A study of potential materials, construction and maintenance2014In: Electric Vehicle Conference (IEVC), 2014 IEEE International, IEEE conference proceedings, 2014, p. 1-5Conference paper (Other academic)
    Abstract [en]

    As a future-oriented industry, the electrified mobility has the potential to enhance the sustainability of our road transportation sector radically. With the aim to break the EV batteries’ bottleneck (e.g., cost, range anxiety, long waiting time) by focusing not on the battery but on the solution to charge it conveniently, different on-the-road-charging solutions have been found under active investigation. From a road infrastructure perspective, however, little attention has been given to the practical, physical roads where these charging solutions will be enabled. In reality, good performance of E-Road infrastructure in aspects such as robustness, durability, costeffectiveness will be crucial for the final success. Taking the Inductive Power Transfer (IPT) charging solution in a dynamic way as a basis, this paper mainly discusses about the physical infrastructural aspect i.e. the road infrastructural materials and the changed construction and maintenance principles. The paper aims to give developers in this field more awareness of the necessity and potential cross-coupling benefits from interdisciplinary collaboration, by taking the road infrastructure research into the concept development of E-Roads.

  • 17.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Towards new infrastructure materials for on-the-road charging A study of potential materials, construction and maintenance2014In: 2014 IEEE INTERNATIONAL ELECTRIC VEHICLE CONFERENCE (IEVC), IEEE , 2014Conference paper (Refereed)
    Abstract [en]

    As a future-oriented industry, the electrified mobility has the potential to enhance the sustainability of our road transportation sector radically. With the aim to break the EV batteries' bottleneck (e.g., cost, range anxiety, long waiting time) by focusing not on the battery but on the solution to charge it conveniently, different on-the-road-charging solutions have been found under active investigation. From a road infrastructure perspective, however, little attention has been given to the practical, physical roads where these charging solutions will be enabled. In reality, good performance of E-Road infrastructure in aspects such as robustness, durability, cost-effectiveness will be crucial for the final success. Taking the Inductive Power Transfer (IPT) charging solution in a dynamic way as a basis, this paper mainly discusses about the physical infrastructural aspect i.e. the road infrastructural materials and the changed construction and maintenance principles. The paper aims to give developers in this field more awareness of the necessity and potential cross-coupling benefits from interdisciplinary collaboration, by taking the road infrastructure research into the concept development of E-Roads.

  • 18.
    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.

  • 19.
    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.
    Kringos, Nicole
    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 materials2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526Article in journal (Other academic)
    Abstract [en]

    It is well-known that the high cost and limited performance of existing energy storage systems have significantly constrained the commercialization of the Electric Vehicle (EV) at large scale. In recent years, attention has been given not only to the improved energy storage systems but also to develop appropriate charging infrastructures that would allow the EVs to be powered in an easier way. Inductive Power Transfer (IPT) technology, also known as a near-field wireless power transfer technology, is capable of delivering electricity wirelessly with large power and high efficiency at a given gap distance. It is therefore seen as a promising solution to be applied in an electrified road (eRoad) to charge EVs dynamically, i.e. while they are moving. Various technical aspects of this contactless charging solution have been studied actively by system developers, such as the charging power, its efficiency, the optimum gap distance as well safety issues. Focus in this study is placed on the effect of pavement surfacing materials on the wireless power transfer efficiency, after the integration of the technology into the physical road structures. Specifically, a combined experimental and model prediction analysis has been carried out to investigate this potential energy loss in a quantitative way, based on which some preliminary conclusions as well as a prioritization of future focus needs are summarized in detail. This work provides thus an important beginning for understanding the pavement materials’ influence on the IPT systems that may be used for dynamic applications in an eRoad.

  • 20.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Electrification of Roads: Opportunities and Challenges2015In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 150, p. 109-119Article in journal (Refereed)
    Abstract [en]

    The Electrical Vehicle (EV) has become a potential solution for enhancing the sustainability of our road transportation, in view of the environmental impacts traditional vehicles have regarding emissions and use of fossil fuel dependence. However, the widespread use of EVs is still restrained by the energy storage technologies, and the electrification of road transportation is still in its early stages. This paper focuses on the technical aspects related to the ‘electrification of roads’ (called ‘eRoads’) infrastructure that aims to diminish the limitations for using EVs. A historical overview of the technology development towards the electrification of road transportation is presented, along with an overview of prospective technologies for implementing an eRoad charging infrastructure. Of these, the Inductive Power Transfer (IPT) technology is examined in further details. The main objective of this paper is to explore the potential knowledge gaps that need to be filled for a successful integration of IPT technology within actual road infrastructure. As such, this paper can be used as an overview of the current state-of-the-art of eRoad infrastructure and also as guidance towards future research directions in this domain.  

  • 21.
    Chen, Feng
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Taylor, Nathaniel
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    A study on dielectric response of bitumen in the low-frequency range2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, p. 153-169Article in journal (Refereed)
    Abstract [en]

    From the current state of literature, the dielectric property of bitumen has not been understood extensively, nor its relation with other properties such as polarity and rheology. In this study, dielectric spectroscopy measurement in a low-frequency range (10−2–106 Hz) was performed on both pure bitumen in different grades and wax-modified bitumen (WMB). From the performed tests we found the following: (i) the dielectric response of base bitumen is strongly temperature and frequency dependent, which is also highly linked to the rheology of the system. (ii) No remarkable differences in the dielectric constant (Formula presented.) among different grades of bitumen from the same crude oil source can be seen. (iii) Regular changes of dielectric loss tangent (tan δ) among the different grades of bitumen can be observed, which can be a good indicator for the linkage between the dielectric and rheological responses. In addition, it can also be perceived that the dielectric spectroscopy may have the potential to become a new approach for the multi-scale characterisation of road infrastructure materials.

  • 22. Copeland, A.
    et al.
    Kringos, Nicole
    TU Delft, The Netherlands.
    Determination of Bond Strength as a Function of Moisture Content at the Aggregate-Mastic Interface2006In: 10th International Conference on Asphalt Pavements, 2006, p. 709-718Conference paper (Refereed)
    Abstract [en]

    Moisture infiltration into asphalt mixes can have a negative effect on the material characteristics of the individual components and damages the bond between the components, leading to separation of the aggregates from the asphalt mixture (i.e. stripping). The phenomenon of stripping is a complicated process, which involves a combination of physical, chemical and mechanical processes. In this paper, focus is placed on damage to the aggregate-mastic bond caused by a weakening of the interface due to diffusion of moisture. The adhesive tensile strength of the interface between thin film asphalt mastic and a diabase aggregate substrate is determined via a modified version of ASTM D 4541 Pull-Off Strength of Coatings Using Portable Adhesion Testers. Experimental results of the pull-off test are linked to moisture diffusion simulations via the finite element analysis tool RoAM (Raveling Of Asphaltic Mixtures), developed at Delft University of Technology. On the basis of this combination of experimental measurements and computational analyses, for the first time, bond strength degradation as a function of the amount of moisture at the mastic-aggregate interface is established. The paper gives an extensive description of the proposed methodology and identifies future research on the topic.

  • 23. Copeland, A.
    et al.
    Kringos, Nicole
    TU Delft, The Netherlands.
    Youtcheff, J.
    Scarpas, A.
    Measurement of Aggregate-Mastic Bond Strength in the Presence of Moisture: A Combined Experimental - Computational Study2007In: Proceedings 86th Annual Meeting, Transportation Research Board, January 2007, 2007Conference paper (Refereed)
  • 24. Das, Prabir Kumar
    et al.
    Baaj, Hassan
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Tighe, Susan
    Coupling of oxidative ageing and moisture damage in asphalt mixtures2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, p. 265-279Article in journal (Refereed)
    Abstract [en]

    In this paper, a possible way to capture the combined effect of oxidative ageing and moisture damage on mixture performance has been proposed. The formulations that are needed for finite element (FE) modelling of oxygen and moisture diffusion process have been established. The proposed model should be able to link the in-time changes to the mastic as function of mixture morphology, ageing propensity and the moisture diffusion properties to the physical properties of the asphalt mixture due to the loss of adhesive and/or cohesive bonding. Such an FE model can help find the trends and relationships that can assist in the development of predictive pavement performance model. Also, from this, one can figure out the key parameters that are mainly responsible for ageing-moisture-induced premature damage of asphalt pavements.

  • 25. Das, Prabir Kumar
    et al.
    Baaj, Hassan
    Tighe, Susan
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Atomic force microscopy to investigate asphalt binders: a state-of-the-art review2016In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 17, no 3, p. 693-718Article in journal (Refereed)
    Abstract [en]

    Atomic force microscopy (AFM) is a non-destructive imaging tool, which is capable of qualitative and quantitative surface analysis with sub-nanometer resolution. Simultaneously with the topology at the micro-scale, AFM is capable of acquiring micro-mechanical information such as relative stiffness/Young's modulus, stickiness/adhesion, hardness, energy loss and sample deformation quantitatively. This paper presents an extensive review on the applications of AFM to investigate different physiochemical properties and performances of asphalt binder. AFM techniques and principles, different sample preparation techniques and its effect on observed micro-structures, chemical origin, surface or bulk phenomenon and temperature sensitivity of these micro-structures are also discussed in this paper. All of the studies conducted on this topic clearly indicated that AFM can successfully be utilised as a tool to better understand how the surface morphology and its physicochemical properties are interlinked and related to the binder performances.

  • 26.
    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.

  • 27.
    Das, Prabir Kumar
    et al.
    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.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Investigation of the asphalt mixture morphology influence on its ageing susceptibility2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 4, p. 987-1000Article in journal (Refereed)
    Abstract [en]

    The main objective of this study is to investigate the influence that asphalt mixture morphology aspects have on its overall ageing behavior. Since mixture morphology is controllable, having insight into how the various morphological parameters influence the mixture’s long-term behavior can be of great value to optimize its design, regardless of the individual material properties. To do so, this study is utilizing a new framework to characterize the combined effect of aggregate packing, average air void size, porosity and level of compaction on ageing for a large set of data from different sources of field compacted and laboratory produced asphalt mixtures. The paper also hypothesizes about the mechanisms that lay behind the found influences and how thus mixture design improvements can be made. From all the investigated cases, it was found that the framework can be used to optimize the durability performance of asphalt mixtures. It was also observed that prediction of ageing behavior without considering the influence of mixture morphology may lead to erroneous conclusions and non-optimal mix design.

  • 28.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    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.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Atomic Force Microscopy to Characterize the Healing Potential of Asphaltic Materials2012In: Atomic Force Microscopy - Imaging, Measuring and Manipulating Surfaces at the Atomic Scale / [ed] Victor Bellitto, InTech, 2012, p. 209-230Chapter in book (Refereed)
  • 29.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    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.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Micro-Mechanical Investigation of Low Temperature Fatigue Cracking Behaviour of Bitumen2012In: 7th RILEM International Conference on Cracking in Pavements: Mechanisms, Modeling, Testing, Detection and Prevention Case Histories / [ed] Scarpas, A.; Kringos, N.; Al-Qadi, I.; Loizos, A., Springer Netherlands, 2012, p. 1281-1290Conference paper (Refereed)
    Abstract [en]

    In an effort to understand the effect of low temperature fatigue cracking, atomic force microscopy (AFM) was used to characterize the morphology of bitumen. In addition, thermal analysis and chemical characterization was done using differential scanning calorimetry (DSC) and thin-layer chromatography/flame ionization detection (TLC/FID), respectively. The AFM topographic and phase contrast image confirmed the existence of bee-shaped microstructure and different phases. The bitumen samples were subjected to both environmental and mechanical loading and after loading, micro-cracks appeared in the interfaces of the bitumen surface, confirming bitumen itself may also crack. It was also found that the presence of wax and wax crystallization plays a vital role in low temperature cracking performance of bitumen.

  • 30.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Wallqvist, Viveca
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Micromechanical investigation ofphase separation in bitumen bycombining atomic force microscopywith differential scanning calorimetryresults2013In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no S1, p. 25-37Article in journal (Refereed)
    Abstract [en]

    The thermo-rheological behaviour of bitumen depends largely on its chemical structure and intermolecular microstructures. Bitumen is a complex mixture of organic molecules of different sizes and polarities for which the micro-structural knowledge is still rather incomplete. Knowledge at that level can have great implications for behaviour at a larger scale and will help to optimise the bitumen in its production stage. The present study is focused on understanding the fundamental mechanisms behind the micro-structural phase appearance and the speed or mobility at which they change. To do so, atomic force microscopy was utilised at different temperatures to investigate the phase separation behaviour for four different types of bitumen and co-relate it with the differential scanning calorimetry measurements. Based on the experimental evidences, it was found that the observed phase separation is mainly due to the wax/paraffin fraction presence in bitumen and that the investigated bitumen behaves quite differently. Recommendations are made to continue this research into qualitative information to be used on the asphalt mix design level.

  • 31.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    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.
    Micro-scale investigation of oxygen diffusion on bitumen surfaces2014In: Asphalt Pavements - Proceedings of the International Conference on Asphalt Pavements, ISAP 2014, CRC Press, 2014, Vol. 1, p. 935-942Conference paper (Refereed)
    Abstract [en]

    This study investigates the evolution of microstructures due to oxygen diffusion on bitumen surface and its effect on bulk properties utilizing Atomic Force Microscopy (AFM) and Differential Scanning Calorimetry (DSC). The bitumen specimens were conditioned in four different modes: both light and air, only air but no light, only light but no air and neither light nor air, for 15 and 30 days. From the AFM investigation after 15 and 30 days of conditioning period, it was found that the percentages of microstructure on the surface reduced with ageing. The DSC heating scan showed that the amount of wax remains constant even after the systematic conditioning. Interestingly, during the cooling cycle, crystallization of wax molecules started earlier for the oxidized specimens than the non-oxidized one. The analysis of the obtained results indicated that the oxidation created a thin film upon the exposed surface, which acts as a barrier and creates difficulty for the wax induced microstructures to float up at the surface. From the DSC analysis, it can be concluded that the oxidation product induced impurities in the bitumen matrix, which acts as a promoter in the crystallization process.

  • 32.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    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.
    Microscale investigation of thin film surface ageing of bitumen2014In: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 254, no 2, p. 95-107Article in journal (Refereed)
    Abstract [en]

    This paper investigates the mechanism of bitumen surface ageing, which was validated utilizing the atomic force microscopy and the differential scanning calorimetry. To validate the surface ageing, three different types of bitumen with different natural wax content were conditioned in four different modes: both ultraviolet and air, only ultraviolet, only air and without any exposure, for 15 and 30 days. From the atomic force microscopy investigation after 15 and 30 days of conditioning period, it was found that regardless the bitumen type, the percentage of microstructure on the surface reduced with the degree of exposure and time. Comparing all the four different exposures, it was observed that ultraviolet radiation caused more surface ageing than the oxidation. It was also found that the combined effect was not simply a summation or multiplication of the individual effects. The differential scanning calorimetry investigation showed that the amount of crystalline fractions in bitumen remain constant even after the systematic conditioning. Interestingly, during the cooling cycle, crystallization of wax molecules started earlier for the exposed specimens than the without exposed one. The analysis of the obtained results indicated that the ageing created a thin film upon the exposed surface, which acts as a barrier and creates difficulty for the wax induced microstructures to float up at the surface. From the differential scanning calorimetry analysis, it can be concluded that the ageing product induced impurities in the bitumen matrix, which acts as a promoter in the crystallization process.

  • 33.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    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.
    Numerical study on the effect of mixture morphology on long-term asphalt mixture ageing2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 16, no 8, p. 710-720Article in journal (Refereed)
    Abstract [en]

    Asphalt mixtures with similar percentages of air voids can have different morphologies and can age differently. Prediction of ageing behaviour without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. This article investigates the long-term field ageing of asphalt mixtures by incorporating mixture morphology. For this, a computational analysis on diffusion-reaction process has been conducted by implementing fundamental mechanism of ageing and conducting a parametric sweep of the morphology. To investigate the ageing gradient along the depth of asphalt mixture, diffusion controlled oxidative ageing on one dense and one open-graded field core was investigated. The proposed model based on the mixture morphology information was able to predict the aged viscosity better than the existing model. As mixture morphology is controllable, having insight into how the morphology parameter influences the mixture's ageing susceptibility can be of great value to its design.

  • 34.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    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.
    Towards a Multi-scale Framework to Optimize Ageing Resistance of Asphaltic Materials2013In: Multi-Scale Modeling and Characterization of Infrastructure Materials: Proceedings of the International RILEM Symposium Stockholm, June 2013 / [ed] Niki Kringos, Björn Birgisson, David Frost, Linbing Wang, Springer Netherlands, 2013, , p. 434p. 285-295Conference paper (Refereed)
    Abstract [en]

    This paper describes an ongoing research project that is aiming at developing a comprehensive multi-scale approach to optimize the ageing resistance of asphaltic mixtures. In this, ageing has been focused on oxidative ageing, but allows future extension to other ageing mechanisms. The developed framework considers three different scales: the nano, micro and meso-scale which are defined as the bitumen phase, the mastic phase and the mixture phase, respectively. In nano-scale, atomic force microscopy and calorimetry are coupled to each other to give insight into how bitumen phase separation evolves and the mobility of microstructure changes with temperature and ageing. On the micro-scale, the energy dissipation as a function of ageing is measured and coupled to the phase behavior information from the nano-scale. On the meso-scale a morphology framework is defined, capable of identifying the dominant mixture morphology parameters that control mixture performance under ageing conditions. By coupling the three scales, the dominant parameters that control ageing of asphaltic mixtures can be defined, modeled and analyzed and as such a tool is created that has the potential of enhancing the sustainability of asphaltic mixtures.

  • 35. Drescher, A
    et al.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    On the Behavior of a Parallel Elasto-Visco-Plastic Model for Asphaltic Materials2010In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 42, no 2, p. 109-117Article in journal (Refereed)
    Abstract [en]

    The paper considers a dissipation energy based elasto-visco-plastic constitutive modelformulated by coupling in parallel visco-elastic and elasto-plastic components, which has been developed at Delft University of Technology for the response prediction ofasphaltic materials. To discuss the various aspects of the model under different creep loads, a simplified one-dimensional analytical solution is derived. Three different analytical cases are treated: visco-elastic response, elasto-visco-plastic response in which plasticity develops during the loading and instantaneous plasticity. The analyses show that the interaction between the parallel visco-elastic and elasto-plasticcomponents of the model are an important aspect of the predictive capabilities of themodel. A case is derived in which short duration loading of the model could lead to aprediction of increasing strains during the unloading phase. Care should be taken when choosing the material parameters of the model to avoid this erroneous prediction. 

  • 36.
    Guarin, Alvaro
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Khan, Abdullah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Butt, Ali Azhar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. Aston University School of Engineering and Applied Science, Aston Triangle, Birmingham, United Kingdom.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    An extensive laboratory investigation of the use of bio-oil modified bitumen in road construction2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 106, p. 133-139Article in journal (Refereed)
    Abstract [en]

    Several roads in Iceland with bio-oil modified surface dressings exhibited severe distresses such as bleeding, binder drain down, and eventually as surface dressing sticking to tires. Samples from six road sections were evaluated in the laboratory to determine the causes of the failure. Binders with and without bio-oil, rapeseed oil and fish oil, were evaluated through a comprehensive rheological and chemical characterization. Both oils, exhibited solubility issues with the bitumen; consequently, the oils covered the aggregates, preventing bonding between binder and stones. It appears that fish oil worked a little better than rapeseed oil for binder modification.

  • 37.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Bidewell, Nathan
    Griffith School of Engineering .
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Evaluation of Environmental Susceptibility of Bituminous Mastic Viscosity as a Function of Mineral and Biomass Fillers: 2013In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2371, p. 23-31Article in journal (Refereed)
    Abstract [en]

    Bituminous mastics influence many other important asphalt mixture properties in addition to their own allowance for the load transfer in the aggregate skeleton. The influence of bituminous mastics extents to the overall stability of a mixture, air void distribution, bitumen draindown during transport, a mixture's workability during the laying process, and the overall in-time performance of the pavement. To understand the properties of asphalt mixtures and their resistance to environmentally induced failure mechanisms, it is paramount to study not only bitumen and the asphalt mixture but also the mastic itself. Current asphalt design procedures do not take mastic behavior into account, however; this omission leads to a significant flaw in the ability to design and predict asphalt concrete response. This paper presents the results of an ongoing research project to enhance the understanding of the mastic phase as well as to develop a new test protocol to characterize mastics. A description is given of the measurements of mastic viscosity for different types of mastics in which the bitumen source is kept as a constant but with varying fillers as well as concentrations. Environmental susceptibility was investigated by subjecting the samples to aging and moisture conditioning. Biomass fillers were included in some of the mastics, in addition to some of the traditional fillers, to show their impact on the viscosity under varying conditions. Results showed that the developed test protocol was able to identify clearly the impact of filler properties on the mastic viscosity. A critical filler concentration was identified beyond which the viscosity behavior became nonlinear. The results also showed that moisture and aging had significant effects on the viscosity of mastics.

  • 38.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Effect of mixing sequence on the workability and performance of asphalt mixtures2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, p. 197-213Article in journal (Refereed)
    Abstract [en]

    In Sweden, during recent years, a new type of mixing protocol has been applied, in which the order of mixing is changed from the conventional method. Improved workability and diminished mixing and compaction energy needs have been important drivers for this. Considering that it is the mastic phase, which is modified by changing the mixing order, it provides an interesting case study for explaining the mechanisms of workability in connection with the mastic phase. To do so, an analytical viscosity framework was combined with a mixture morphology framework to upscale to the mixing level and tribology principles to explain the interaction between the mastic and the aggregates. From the mastic viscosity protocol, it was found that the mixing order significantly affects the resulting mastic viscosity. To analyse the effect of this on the workability and resulting mixture performance, X-ray computed tomography was used to analyse mixtures produced by the two different mixing sequences. Mechanical testing was utilised to determine the long-term mechanical performance. In this part of the study, mastic viscosity as a function of particle concentration and distribution was directly coupled to improved mixture workability and enhanced long-term performance.

  • 39.
    Hesami, Ebrahim
    et al.
    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.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    A new protocol for measuring bituminous mastic viscosity as a function of its filler concentration2014In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 15, no 2, p. 420-433Article in journal (Refereed)
    Abstract [en]

    In this contribution the development and results of a new test protocol for measuring the viscosity of bituminous mastics are presented. The paper describes the various considerations that need to be taken into account when dealing with mastics, gives a detailed description of the sample preparation, the test set-up and the actual test performance. A demonstration of the use of the test procedure is given by developing three types of mastics in which different filler types, but a similar bitumen base, were used. From the results it can be seen that the developed protocol is sensitive enough to allow for detailed studies of the effect of filler shape, chemistry and size distribution. In continuation of this work, more types of mastics will be investigated and the test results will be linked to additional chemical and mechanical test results to further enhance the fundamental understanding of mastics.

  • 40.
    Hesami, Ebrahim
    et al.
    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.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Effect of mixing sequence on the workability and performance of asphalt mixturesIn: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Other academic)
  • 41.
    Hesami, Ebrahim
    et al.
    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.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Numerical and experimental evaluation of the influence of the filler-bitumen interface in mastics2014In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 47, no 8, p. 1325-1337Article in journal (Refereed)
    Abstract [en]

    The successful use of additives in modified asphalt mixtures, such as warm mix asphalt, depends largely on the effect such modification has on the mastic. Previous research indicated that such modifiers do not simply change the bitumen properties, but can also change the interaction between the filler and the bitumen matrix. Understanding the effect of the properties of the fillers, the bitumen and their interaction is thus important for future asphalt mix design. In order to investigate this and to define the dominant relationships, this paper combines a numerical and experimental approach. In the experiments, the viscosities of modified and unmodified mastics with different filler concentrations and types were systematically investigated utilizing a novel testing protocol. In the numerical analyses, the Finite Element Method was utilized for a micro-mechanical analysis, in which the shape and size of the filler particles were varied in the bitumen matrix. Combining the experimental and numerical results allowed for a detailed investigation of the effect of the interface properties, with and without modifiers. The research further indicated that the effect of the shape and size of the fillers varied, depending on the interface properties. From the research relationships were established between the overall mastic viscosity and the influence of the filler-bitumen interface, considering shape and size. The conclusion of this paper can thus be useful for the effective development of modified asphalt mixtures and gives strong indications towards future research directions.

  • 42.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    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.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Towards a New Experimental and Numerical Protocol for Determining Mastic Viscosity2012In: 7th RILEM International Conference on Cracking in Pavements, 2012, p. 103-113Conference paper (Refereed)
    Abstract [en]

    The rheological characteristics of mastics, or filler-bitumen mixtures, as a component of asphalt mixtures have a significant effect on the overall in-time performance of asphalt pavements such as low temperature cracking, fatigue and rutting behaviour. Viscosity is one of the rheological characteristics which is influenced by the physico-chemical filler-bitumen interaction. In this study, after reviewing some of more often used theories for calculating the viscosity of suspensions, a framework for calculating the viscosity of mastics is presented. This framework aims at covering the entire range of filler concentrations that is found in mastics. Also, a procedure for measuring viscosity mastic from dilute to high concentration mastic using a vane rotor viscometer is introduced. The paper is presenting the first experimental results and discusses the effect of the shape of the investigated fillers on the measured viscosity of the mastics.

  • 43.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    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.
    An empirical framework for determining asphalt mastic viscosity as a function of mineral filler concentration2012In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 35, p. 23-29Article in journal (Refereed)
    Abstract [en]

    Sufficient coating, easy paving and good compaction are desirable parameters, which are approachable with the optimum viscosity of the mastic. In many studies, models have been developed for calculating the viscosity for different types of suspensions at various particle-to-fluid ratios. Unfortunately, none of them are applicable to asphalt mastics, since this material has a much wider range of mineral filler concentration from dilute to very concentrate. To give an overview of the existing viscosity models and to evaluate their range of applicability to asphalt mastics, an extensive literature review was performed. A new empirical framework was developed that removes some of the stipulated limitations of the existing theories.

  • 44.
    Hesami, Ebrahim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Nejad Ghafar, Ali
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Multi-Scale Characterization of Asphalt Mastic Rheology2013In: Multi-Scale Modeling and Charactrization of Infrastructure Materials: Proceedings of the International RILEM Symposium Stockholm, June 2013 / [ed] Niki Kringos, Björn Birgisson, David Frost and Linbing Wang, Springer, 2013, p. 45-61Conference paper (Refereed)
    Abstract [en]

    Understanding the influence of the fundamental parameters on asphalt mastic rheology is an important step towards improving the quality of asphalt mixtures. Due to the size of fillers and the sensitivity of the rheological behaviour of mastic, it is not always possible to study the effect of all parameters at one scale. Hence in this study, a theoretical framework is established for calculating the relative viscosity of asphalt mastics as a function of its filler concentration. Furthermore, a new test protocol is introduced for measuring the viscosity of asphalt mastic at higher temperatures and different filler concentrations.  To characterize the fillers and their agglomeration and distribution inside solid mastics, X-ray tomography, laser scattering, scanning electron microscopy, BET and Helium Pycnometery were utilized. To characterize the energy dissipation potential of the mastics under cyclic loads, as a function of their fillers, the dynamic mechanical analyzer was utilized. The research shown in this paper further investigated the various dominant parameters related to fillers and bitumen in mastics and relate them to the workability and resulting mechanical properties and developed an overall framework to connect different scales. The developed characterization protocols have the potential to allow the asphalt engineers to design their hot and warm asphalt mixtures on a more fundamental and thus sustainable basis.         

  • 45.
    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.  

  • 46.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Effects of surfactants and adhesion promoters on the bitumen-minerals interfacial bond during breaking of bitumen emulsionsIn: Article in journal (Refereed)
    Abstract [en]

    Cold mix asphalt (CMA) emulsion technology has been the subject of research for many decades due to its proven environmental and economic benefits. However, issues relating to its mechanical performance still need to be investigated in order to understand the breaking mechanisms of bitumen emulsions and the surface chemistry involved. Bitumen emulsions are designed to break in a controlled manner to achieve the required level of performance for producing good quality cold asphalt mixtures. In this work, experiments on the coalescence of two bitumen droplets were carried out on a selected grade of Nynas bitumen. In an emulsion environment, the cohesion between bitumen droplets as well as their adhesion to a mineral surface was investigated. The cohesion and adhesion properties were analyzed by varying selected surfactant types and adhesion promoters in the water phase. The research showed that the presence of emulsifiers (with concentrations above the critical micelle concentration) in the water phase inhibits the adhesion of bitumen droplets to the mineral surface. However, a very small addition (0.02%) of adhesion promoter reverses the situation completely, and adhesion is dominant rather than cohesion. Moreover, the kinetics of the coalescence process is strongly controlled by the water phase temperature.

  • 47.
    Khan, Abdullah
    et al.
    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.
    Evaluation of adhesive properties of mineral-bitumen interfaces in cold asphalt mixtures2016In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 125, p. 1005-1021Article in journal (Refereed)
    Abstract [en]

    The performance of asphalt mixtures is strongly influenced by the physical and chemical properties of the minerals and binders used, at various micro to macro scales. In cold asphalt mixtures a process that particularly strongly influences adherence between the minerals and binders (and thus performance) is the wetting of bitumen on the minerals’ surfaces. Their adhesion is influenced by numerous factors and parameters, such as surface free energies of both binders and aggregates in the presence of moisture or dust on the surface of aggregates, mixing temperatures, surface textures including open porosity, nature of the minerals and their surface chemical composition, as well as additives present in the binder phase. However, the relationships involved are not fully understood. Thus, iowever

    n this study the surface free energies of both minerals/aggregates and binders were characterized using two approaches, one based on contact angles and the other on vapor sorption methods. Precise specific surface areas of four aggregates and seven minerals were determined using BET (Brunauer, Emmett and Teller) theory, by measuring the physical adsorption of selected gas vapors on their surfaces, and calculating amounts of adsorbed vapors corresponding to monolayer occupancy on the surfaces. Interfacial bond strengths between bitumen and aggregates were also calculated, based on measured surface free energy components of minerals/aggregates and binders, in both dry and wet conditions. The adhesive bond strength for the binder with each mineral/aggregate combination in wet condition has been improved by using additives. The presented study has highlighted the need for accurate measurements of aggregates’ and minerals’ specific surface areas and (hence) requirements to develop new approaches to resolve problems associated with BET-based methods.

     

  • 48.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Investigating effects of salts on the coalescence process in bitumen emulsionsIn: Article in journal (Refereed)
    Abstract [en]

    The breaking and coalescence process in bitumen emulsions during their application strongly influences the resulting long-term mechanical performance of the cold mix asphalt. This phase separation process is affected by physico-chemical changes at the bitumen/water interface. This paper describes the effects of addition of different salts on the destabilization of bitumen emulsions. This study is limited mainly to cationic rapid setting (CRS) bitumen emulsions and salts which are very commonly added to these emulsions as a stabilizer. However, a few samples with non-ionic emulsifiers were also prepared and analyzed comparatively to understand the electrostatic force balance with varying concentrations of selected salts. The experimental part includes a bitumen droplet relaxation test, droplet size distribution measurement, microscopy, and evaluation of physico-chemical properties of prepared soap solutions e.g. interfacial tension and density measurements. Some experiments on the effect of selected water-soluble organic solvents on the coalescence process were also carried out. The results showed that coalescence was delayed after the addition of salts, while the water soluble organic solvents proved not to affect the emulsion significantly. 

  • 49.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Redelius, Per
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Surface energy measurements and wettability investigation of different minerals and bitumen for cold asphalts2014In: Asphalt Pavements - Proceedings of the International Conference on Asphalt Pavements, ISAP 2014, CRC Press, 2014, Vol. 1, p. 61-70Conference paper (Refereed)
    Abstract [en]

    For environmental reasons, low installation cost and initial investment; low energy infrastructure materials are becoming of high interest. A potential option to replace current hot mix asphalts is emulsifications, where bitumen binder is dispersed in a water phase aided by emulsifier and shear forces, and mixed at ambient temperature with unheated stones. Long term performance must, however, be guaranteed, otherwise the application benefits will be significantly diminished. In this paper, the main issues of cold mix (emulsion based) asphalt, like wetting in the presence of moisture and dust, and coalescence issues are discussed. Since both bitumen droplets and mineral surfaces were upscaled, pure mineral surfaces were investigated as stone material consists of different minerals. As a measure of the interfacial bond strength, surface free energies of different mineral aggregates and bitumen have been investigated in this paper as a stepping stone for further analyses of emulsions. From the analyses it was found that bitumen has only dispersive forces whereas most of the minerals surfaces have polar nature. According to Fowke's additive nature of the forces, bitumen and water are roughly equally strongly adsorbed to plagioclase and calcite, whereas water will displace bitumen from quartz, gypsum, potassium feldspar and mica surface.

  • 50.
    Khan, Abdullah
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Redelius, Per
    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.
    Toward a new experimental method for measuring coalescence in bitumen emulsions: A study of two bitumen droplets2016In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 494, p. 228-240Article in journal (Refereed)
    Abstract [en]

    Cold mix asphalt (CMA) emulsion technology could become an attractive alternative for the road industry due to low startup and equipment installation costs, diminished energy consumption and reduced environmental impact. The performance of cold asphalt mixtures produced from emulsions is strongly influenced by a good control of the breaking and coalescence process. The wetting of bitumen on the surface of the aggregates is hereby of major importance for the performance of the asphalt. Premature coalescence of the bitumen emulsions away from the surface, could lead to poor adhesion and decreased mechanical strength of the asphalt. Today, the breaking and coalescence mechanisms of bitumen emulsions are still not fully understood due to their complexities and the lack of fundamental experimental methods and existing models. However, in the past years efforts have been made in defining relationships for understanding the bitumen emulsions. In this paper, a new experimental method is presented to study coalescence of bitumen by using shape relaxation of bitumen droplets in an emulsion environment. The coalescence of spherical droplets of different bitumen have been correlated with neck growth, densification and surface area change during the coalescence process. The test protocol was designed in a controlled climate chamber, to study the coalescence process with varying environmental conditions. The kinetics of the relaxation process was influenced by the temperature as well as other parameters. The research showed that the developed test procedure is repeatable and able to study the coalescence process on a larger scale. However, the relationship between the measured parametric relationships at the larger scale and the bitumen emulsion scale still needs further investigation.

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