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Chen, F. (2020). Vibration-induced aggregate segregation in asphalt mixtures. Materials and Structures, 53(27)
Open this publication in new window or tab >>Vibration-induced aggregate segregation in asphalt mixtures
2020 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 53, no 27Article in journal (Refereed) Published
Abstract [en]

Aggregate segregation in asphalt mixture is a bothersome engineering issue during pavement construction. The practitioners have some measures to mitigate the segregation potential based on experiences which, however, can only reduce the risk to a certain extent. In this research, the authors aim to contribute to the discussion in a rational non-empirical way, by using novel experimental and numerical techniques. A case study is carried out to investigate the vibration-induced segregation in asphalt mixtures, corresponding to the circumstance arising during material transportation to the construction site. A novel experimental test is conducted for evaluating the segregation characteristics of asphalt mixtures under vertical vibration in laboratory conditions. A numerical investigation based on discrete element method is further performed to study the phenomenon from a micromechanical point of view. The obtained experimental and numerical results indicate that vibratory loading induces aggregate size segregation in asphalt mixtures, and the degree of segregation is influenced profoundly by the adhesive properties of bituminous binders and the aggregate gradation.

Keywords
Asphalt mixture, size segregation, vibraton, discrete element method
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering, Building Materials
Identifiers
urn:nbn:se:kth:diva-268864 (URN)
Funder
Swedish Research Council Formas, 2012-1349
Available from: 2020-02-24 Created: 2020-02-24 Last updated: 2020-02-24
Chen, F., Jelagin, D. & Partl, M. (2019). Experimental and numerical analysis of asphalt flow in a slump test. International Journal on Road Materials and Pavement Design, 20, S446-S461
Open this publication in new window or tab >>Experimental and numerical analysis of asphalt flow in a slump test
2019 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 20, p. S446-S461Article in journal (Refereed) Published
Abstract [en]

The mechanical behaviour of uncompacted asphalt mixtures is still not well understood,threatening directly to the pavement practices such as control of mixture’s workability andsegregation. This situation may become even worse due to the gradually increasing complexityand advances in paving materials and technologies. This study adopts a slump flow testbased on concrete technology and a Discrete Element (DE)-based numerical tool to investigatethe mechanical behaviour of uncompacted asphalt mixture from a microstructural point ofview, particularly focusing on the bituminous binder effects. The combined experimental andnumerical analysis indicates that bitumen distinctly influences the contact interactions withinthe mixture and thus its macroscopic flow, which can be physically interpreted as a combinedeffect of lubricated friction and bonding force. Additional case studies demonstrate that the DEmodel is capable of simulating the flow response of asphalt mixtures under changed particlecontact conditions and driven force.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Asphalt mixture; slump test; discrete element method; large displacement
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-246052 (URN)10.1080/14680629.2019.1587495 (DOI)000468539800028 ()2-s2.0-85062715193 (Scopus ID)
Funder
Swedish Research Council Formas, 2012-1349
Note

QC 20190319

Available from: 2019-03-12 Created: 2019-03-12 Last updated: 2019-06-24Bibliographically approved
Ghafoori Roozbahany, E. & Partl, M. (2019). Investigation of asphalt joint compaction using discrete element simulation. International Journal on Road Materials and Pavement Design
Open this publication in new window or tab >>Investigation of asphalt joint compaction using discrete element simulation
2019 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed) Published
Abstract [en]

Constructing high quality asphalt joints plays a vital role in preventing premature failures of pavements. Previous studies suggested that many construction parameters directly and indirectly influence the quality of asphalt joints. Due to uncertainties about the influence of each parameter on the quality of the finalised joints, closer and more detailed studies are still needed for achieving further improvements in this field. This study investigates the possible impacts of thickness, bottom layer roughness, joint interface geometries and compaction techniques on the particle flow of a coarse structured mixture during compaction. Therefore, discrete element method (DEM) was utilised to evaluate the influence of each construction parameter on the interlock between the cold and the hot side of an asphalt pavement joint. The results helped to explain earlier experimental findings about the joints and revealed potential for further laboratory and field investigations.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2019
Keywords
asphalt joints, discrete element simulation, compaction
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-255197 (URN)10.1080/14680629.2019.1594055 (DOI)000472268100001 ()2-s2.0-85067446671 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-17Bibliographically approved
Fadil, H., Jelagin, D., Larsson, P.-L. & Partl, M. (2019). Measurement of the viscoelastic properties of asphalt mortar and its components with indentation tests. International Journal on Road Materials and Pavement Design
Open this publication in new window or tab >>Measurement of the viscoelastic properties of asphalt mortar and its components with indentation tests
2019 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed) Published
Abstract [en]

Reliable determination of material properties is a key component for modelling and performance prediction of asphalt pavements. This paper deals with the potential use of instrumented indentation tests for viscoelastic characterisation of asphalt mortar as a new alternative to existing techniques. The main focus lies on the potential of indentation tests for multi-scale measurement of the shear relaxation modulus. A three-dimensional finite element model of a rigid spherical indenter penetrating an asphalt mortar sample is developed and used to model indentation tests performed at different material scales. The asphalt mortar is modelled as an idealised fine aggregate composite with elastic spheres, suspended within a viscoelastic bitumen mastic matrix. Based on the obtained numerical results the scale-dependency of the shear relaxation modulus measured with the indentation test is investigated. It is shown that the measurement scale is effectively controlled by the size of the indenter-specimen contact area, while the effect of indentation depth is minimal. The minimum contact area size required for obtaining representative properties, measured at the mortar scale, is determined. The viscoelastic parameters obtained from the indentation model are compared to those obtained using a representative volume element (RVE) for the asphalt mortar. In this way, the paper provides a new impulse for linking the mortar and asphalt scales in the multiscale modelling of asphalt mixtures. Feasibility of the proposed testing technique is further evaluated experimentally. Viscoelastic indentation tests are performed on asphalt mastics and mortar at two different sizes of contact areas. Experimental results indicate that indentation tests allow reliable characterisation of mortars relaxation modulus on both macro-scale as well as on individual component level.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2019
Keywords
indentation testing, asphalt mortar, bitumen-filler mastics, multiscale, viscoelasticity, FEM
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-255414 (URN)10.1080/14680629.2019.1628434 (DOI)000473928500001 ()2-s2.0-85068229189 (Scopus ID)
Note

QC 20190815

Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2020-03-09Bibliographically approved
Ghafoori Roozbahany, E., Partl, M. & Elaguine, D. (2019). Modelling the flow of asphalt under simulated compaction using discrete element. Construction and Building Materials, 227, Article ID 116432.
Open this publication in new window or tab >>Modelling the flow of asphalt under simulated compaction using discrete element
2019 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 227, article id 116432Article in journal (Refereed) Published
Abstract [en]

The flow differences between the particles of asphalt mixtures compacted in the laboratory and in the field have been identified as one of the reasons for the discrepancies between laboratory and field results. In previous studies, the authors developed a simplified test method, the so-called compaction flow test (CFT), for roughly simulating the flow of particles in asphalt mixtures under compacting loads in laboratory. The CFT was used in different studies to examine its capability of revealing the differences between the flow behavior of different asphalt mixtures under various loading modes. The promising results encouraged further development of the CFT by investigating the possible impacts of simplifications and boundary conditions on the results of this test. For this reason, discrete element method (DEM) was utilized to investigate possible impacts of the mold size, geometry of the loading strip as well as the loading rate on the results of the CFT. The results of the simulation indicate that in case of wearing course layers with nominal maximum aggregate size of 11 mm, the length of the CFT mold can be increased from 150 mm to 200–250 mm for reducing flow disturbances from the mold walls. However, since the majority of the flow of asphalt mixture particles is expected to take place within the first 100–150 mm length of the mold, reasonable results can still be obtained even without changing the size of the CFT mold. Moreover, comparing results with different loading strip geometries and loading rates indicates that the current CFT setup still appears to provide consistent results.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Asphalt compaction, Boundaries, Compaction flow test, Discrete element, Compaction, Finite difference method, Mixtures, Molds, Semiconductor insulator boundaries, Testing, Flow behaviors, Flow disturbances, Flow of particles, Flow tests, Loading strips, Maximum aggregate sizes, Simplified test, Wearing course, Asphalt mixtures
National Category
Building Technologies Other Materials Engineering
Research subject
Materials Science and Engineering; Civil and Architectural Engineering, Building Materials
Identifiers
urn:nbn:se:kth:diva-263465 (URN)10.1016/j.conbuildmat.2019.07.158 (DOI)000496830500013 ()2-s2.0-85070383471 (Scopus ID)
Note

QC 20191205

Available from: 2019-12-05 Created: 2019-12-05 Last updated: 2020-01-07Bibliographically approved
Olsson, E., Jelagin, D. & Partl, M. (2019). New discrete element framework for modelling asphalt compaction. International Journal on Road Materials and Pavement Design
Open this publication in new window or tab >>New discrete element framework for modelling asphalt compaction
2019 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed) Published
Abstract [en]

During asphalt mixture compaction, loads in the material are mainly transferred through contact between the stones and the interaction between the stones and the binder. The behaviour of such materials is suitable to model using the Discrete Element Method (DEM). In this study, a new DEM modelling approach has been developed for studying the asphalt compaction process, incorporating contact and damage laws based on granular mechanics. In the simulations, aggregate fracture is handled by a recently developed method of incorporating particle fracture in DEM, based on previously performed fracture experiments on granite specimens. The binder phase is modelled by adding a viscoelastic film around each DEM particle. This surface layer has a thickness that obtains the correct volume of the binder phase and has mechanical properties representative for the binder at different temperatures. The ability of the model to capture the influence of mixture parameters on the compactability and the eventual stone damage during compaction is examined for the cases of compaction flow test and gyratory compaction. Explicitly, the influence of different aggregate gradations, mixture temperatures and binder properties are studied. The results show that the proposed DEM approach is able to capture qualitatively and quantitatively responses in both cases and also provide predictions of aggregate damage. One large benefit with the developed modelling approach is that the influence of different asphalt mixture parameters could be studied without re-calibration of model parameters. Furthermore, based on comparative DEM simulations, it is shown that the proposed approach provides more realistic force distribution networks in the material.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2019
Keywords
asphalt compaction, discrete element method, modelling, aggregate damage
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-255412 (URN)10.1080/14680629.2019.1633750 (DOI)000473843200001 ()2-s2.0-85068530634 (Scopus ID)
Note

QC 20190814

Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2020-03-09Bibliographically approved
Ghafoori Roozbahany, E., Partl, M. & Guarin, A. (2018). Influence of layer thickness on the flow of asphalt under simulated compaction. In: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017: . Paper presented at 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, 28 June 2017 through 30 June 2017 (pp. 1435-1441). CRC Press/Balkema
Open this publication in new window or tab >>Influence of layer thickness on the flow of asphalt under simulated compaction
2018 (English)In: Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, CRC Press/Balkema , 2018, p. 1435-1441Conference paper, Published paper (Refereed)
Abstract [en]

Compaction is one of the most important phases in the life cycle of asphalt pavements and has therefore been a hot subject of research for a long time. However, despite of valuable research efforts on this topic, a remarkable gap between laboratory and field measurements still remains. Moreover, whereas most of the experimental methods are carried out on compacted pavement material, methods for evaluating compactability of asphalt mixtures for increasing the fundamental knowledge about internal movements within the asphalt during compaction are only scarce. Hence, in this study, a recently developed tool for simulating the compaction process with respect to the particle flow, i.e. Compaction Flow Test (CFT), was used along with simultaneous X-ray imaging for investigating the impact of thickness changes on two different asphalt mixture structures in terms of the compaction effort as well as flow pattern differences. The results of the investigation provided reasonably useful input for building up a better understanding of the behavior of mixtures under compaction loads. This method was able to successfully reveal the differences of the structural rearrangements within the asphalt mixtures for three different lift thicknesses. It also helped to explain some of the previous research studies results in a more comprehensive way. The achievements of this study may serve for developing an in-site evaluating test method for assessing compactability of asphalt mixtures before placing them on the roads.

Place, publisher, year, edition, pages
CRC Press/Balkema, 2018
Keywords
Compactability, Lift thickness, Particle flow, X-ray computed tomography, Bearing capacity, Compaction, Computerized tomography, Flow patterns, Life cycle, Mixtures, Railroads, Compaction effort, Compaction process, Experimental methods, Field measurement, Structural rearrangement, Asphalt mixtures
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-247234 (URN)10.1201/9781315100333-205 (DOI)2-s2.0-85058531077 (Scopus ID)9781138295957 (ISBN)
Conference
10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017, 28 June 2017 through 30 June 2017
Note

QC 20190402

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-02Bibliographically approved
Partl, M. (2018). Introduction. In: RILEM State-of-the-Art Reports: . Paper presented at RILEM State-of-the-Art Reports (pp. 1-14). Springer Netherlands
Open this publication in new window or tab >>Introduction
2018 (English)In: RILEM State-of-the-Art Reports, Springer Netherlands , 2018, p. 1-14Conference paper, Published paper (Refereed)
Abstract [en]

An overview on the background and motivation for this report on the achievements of the technical committee RILEM TC 237-SIB on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems is presented, together with a short summary on the scope of this voluntary international team effort. Challenges and key research paths towards modern “green” asphalt pavements are addressed, focusing on general aspects associated with the increasing variety of approaches and their implication on testing and characterization of innovative asphalt pavement materials. As example for the complexity of the experimental challenges and the potential necessity to break free from traditional testing patterns, selected specific aspects of reinforced asphalt pavements are considered and discussed. It is emphasized that testing must be consistent with the purpose of the reinforcement, answering the key questions in what respect, under what conditions and in what loading direction reinforcement should be achieved and tested. This “garbage-in-garbage-out” awareness is also valid for all other fields dealing with testing and characterization of innovative bituminous materials and systems, of course. 

Place, publisher, year, edition, pages
Springer Netherlands, 2018
Keywords
Aging, Asphalt structure, Green asphalt, Healing, Maturing, Reinforcement, Sustainability
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-227494 (URN)10.1007/978-3-319-71023-5_1 (DOI)2-s2.0-85041555477 (Scopus ID)
Conference
RILEM State-of-the-Art Reports
Note

Export Date: 9 May 2018; Editorial; Correspondence Address: Partl, M.N.; Empa, Swiss Federal Laboratories for Materials Science and TechnologySwitzerland; email: manfred.partl@empa.ch. QC 20180516

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-05-16Bibliographically approved
Partl, M. (2018). Towards improved testing of modern asphalt pavements. Materials and Structures, 51(6), Article ID 166.
Open this publication in new window or tab >>Towards improved testing of modern asphalt pavements
2018 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 51, no 6, article id 166Article in journal (Refereed) Published
Abstract [en]

During the last 50 years, Rilem was continuously active in pre-standardization efforts aiming at gradually improving scientific and technological testing and analysis methods for refined understanding and characterization of bituminous binders and asphalt, both under well-defined laboratory and performance driven in-field conditions. This paper intends to highlight and provide a short overview on the international activities of Rilem’s to date 18 technical committees (TC) on asphalt and bituminous binders. After some general background information, underlining the specific complexity of asphalt pavement materials in terms of rheological behavior and basic structural functioning, it is shown that these activities resulted in numerous recommendations, state of the art reports and conference proceedings, all produced on a voluntary basis by scientific and technical commitment of individual experts. This wealth of results was created by the TCs following an own systematic methodology for many years which, at the end of the day, allowed building up activities through the new TCs of today in a much more specialized but at the same time also more diverse way. In view of this new flexibility and keeping in mind the previous success story of Rilem towards improved testing of asphalt pavements, future developments, challenges and interdisciplinary issues regarding bituminous road materials are outlined as potential starting point for future TC initiatives.

Place, publisher, year, edition, pages
Springer Netherlands, 2018
Keywords
Asphalt, Bitumen, Rilem, Testing, Asphalt pavements, Binders, Background information, International activities, Performance-driven, Rheological behaviors, Systematic methodology, Technical committees
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-247014 (URN)10.1617/s11527-018-1286-9 (DOI)000452071600004 ()2-s2.0-85057625363 (Scopus ID)
Note

QC 20190626

Correction in:Doi: 10.1617/s11527-019-1418-x

WOS: 000502802100005

Available from: 2019-06-26 Created: 2019-06-26 Last updated: 2020-04-02Bibliographically approved
Partl, M. (2017). Editorial. International Journal on Road Materials and Pavement Design, 18, 1-1
Open this publication in new window or tab >>Editorial
2017 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 18, p. 1-1Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Taylor & Francis, 2017
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-208734 (URN)10.1080/14680629.2017.1305526 (DOI)000402301700001 ()2-s2.0-85020161424 (Scopus ID)
Note

QC 20170626

Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2017-06-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1041-0244

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