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Ghafoori Roozbahany, EhsanORCID iD iconorcid.org/0000-0002-5526-5896
Publications (7 of 7) Show all publications
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
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
Ghafoori Roozbahany, E., Partl, M. & Guarin, A. (2017). Introducing a new method for studying the field compaction. International Journal on Road Materials and Pavement Design, 18, 26-38
Open this publication in new window or tab >>Introducing a new method for studying the field compaction
2017 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 18, p. 26-38Article in journal (Refereed) Published
Abstract [en]

The flow of particles during compaction may have a prominent influence on the difference of field and laboratory results as recently demonstrated by the authors with their newly developed compaction flow test (CFT). This test with a simple compaction simulator was used for studying the flow behaviour and rearrangement of particles for mixtures with different structures and thicknesses. However, validating the CFT results for practical purposes requires field measurements that provide more insight into the compaction process and eventually allowing to adjust the CFT for further use as an evaluating in-site tool. This study presents a new method for conducting such measurements during field compaction. In this method, some representative particles are tracked inside asphalt specimens and the accuracy of the results is examined by X-ray computed tomography. The results of the feasibility tests show that this method has potential for further use in the field and for building up a comprehensive basis of knowledge on field compaction towards closing the gap between the field and laboratory results.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keywords
asphalt compaction, CFT, magnetic field, X-ray computed tomography
National Category
Geotechnical Engineering
Identifiers
urn:nbn:se:kth:diva-208735 (URN)10.1080/14680629.2017.1304245 (DOI)000402301700004 ()2-s2.0-85016113084 (Scopus ID)
Note

QC 2017-06-13

Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2017-12-13Bibliographically approved
Ghafoori Roozbahany, E. & Partl, M. (2016). A new test to study the flow of mixtures at early stages of compaction. Materials and Structures, 49(9), 3547-3558
Open this publication in new window or tab >>A new test to study the flow of mixtures at early stages of compaction
2016 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 49, no 9, p. 3547-3558Article in journal (Refereed) Published
Abstract [en]

Workability is one of the most commonly used indicators for the capability of asphalt mixtures tobe placed and compacted on the roads with long lasting quality and minimum maintenancethroughout its service life. Despite of valuable previous efforts for measuring and characterizingworkability, none of them has proven successful in representing the field conditions of roadconstructions. This paper is an attempt towards developing a systematic workability test methodfocusing on compaction, the so-called Compaction Flow Test (CFT), by simulating fieldcompaction at early stages and at laboratory scale with the main focus on mixture flow. The CFTwas applied for different mixtures in order to identify the parameters with highest impact on theasphalt particle movements under compaction forces. A new setting inside X-ray ComputationalTomography (CT) allowed tracing asphalt particles during the CFT and acquiring CT imagesunderlining the reliability of the CFT results. In addition, simple Discrete Element Models (DEM)were successfully generated to justify some of the CFT results.

Place, publisher, year, edition, pages
Kluwer Academic Publishers, 2016
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-176317 (URN)10.1617/s11527-015-0738-8 (DOI)000379590900005 ()2-s2.0-84945556719 (Scopus ID)
Note

QC 20160818

Available from: 2015-11-03 Created: 2015-11-03 Last updated: 2017-12-13Bibliographically approved
Ghafoori Roozbahany, E. (2015). Investigation of asphalt compaction in vision of improving asphalt pavements. (Licentiate dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Investigation of asphalt compaction in vision of improving asphalt pavements
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing.

Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT).

The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. p. xiv, 23
Series
TRITA-BYMA, ISSN 0349-5752 ; 2015:5
Keywords
Cold asphalt pavement joints, asphalt joint laboratory production, IDT joint evaluation, DTT joint evaluation, 4PB joint evaluation, joints FEM analysis. Discrete Element Modeling (DEM), X-ray Computed Tomography (CT), Compaction Flow Test (CFT), Compactability
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-176319 (URN)
Presentation
2015-11-24, B3, Brinellvägen 23, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20151104

Available from: 2015-11-04 Created: 2015-11-03 Last updated: 2015-11-04Bibliographically approved
Ghafoori Roozbahany, E., Partl, M. N. & Guarin, A. (2015). Particle Flow during Compaction of Asphalt Model Materials. Construction and Building Materials, 100(15), 273-284
Open this publication in new window or tab >>Particle Flow during Compaction of Asphalt Model Materials
2015 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 100, no 15, p. 273-284Article in journal (Refereed) Published
Abstract [en]

Compaction is one of the key phases of the pavement construction and has been subject of research for a long time. However, very little is known regarding what really happens during compaction and how the pavement structure and the aggregate skeleton of the asphaltic layer are formed. Studies on that matter are of special practical importance since they may contribute to reduce the possibility of over-compaction and aggregate crushing. In this study, a new test method (Flow Test) was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by model materials to lower the level of complexity for checking the feasibility of the new test method as well as modeling purposes. Geometrically simple materials with densest possible combinations were tested for both dry and coated mixtures. X-ray radiography images were used for evaluating the material flow during compaction for different model mixtures. Results showed the capability of the test method to clearly distinguish mixtures with different properties from one another and also the potential of such a method to be used as an evaluating tool in the field. In addition, a simple discrete element model was applied for better understanding the flow of the model material during compaction as a basis for further improvement when moving from the asphalt model material to real mixtures. Therefore, real mixtures were prepared and tested under the same test configuration as for the model materials. The overall results of the real mixtures were found to support the model material test results.

Place, publisher, year, edition, pages
Elsevier, 2015
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-176318 (URN)10.1016/j.conbuildmat.2015.09.061 (DOI)000364608000029 ()2-s2.0-84944346091 (Scopus ID)
Note

Updated from Accepted to Published. QC 20160210

Available from: 2015-11-03 Created: 2015-11-03 Last updated: 2017-12-13Bibliographically approved
Ghafoori Roozbahany, E., Partl, M. & Witkiewicz, P. J. (2013). Fracture testing for the evaluation of asphalt pavement joints. International Journal on Road Materials and Pavement Design, 14(4), 764-791
Open this publication in new window or tab >>Fracture testing for the evaluation of asphalt pavement joints
2013 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no 4, p. 764-791Article in journal (Refereed) Published
Abstract [en]

Asphalt joints are inevitable parts of every pavement. Although much attention is dedicated to the construction of such joints, reliable tools for assessing the mechanical properties of joints for design and performance assessment are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing pavement as in the case of large patches for pavement repair. This paper intends to evaluate different new or modified static fracture testing methods for ranking existing joint construction techniques. Some of these testing methods, such as indirect tensile test, direct tensile test and 4-point bending test are familiar in the field of asphalt pavement characterisation, but have scarcely been used for assessing the quality of joints so far. These three test types were adopted and evaluated for joints and the test results were analysed with finite element (FE) software ABAQUS. Different joints for testing were prepared in the laboratory using a special specimen construction procedure. The results suggest that joints with inclined interfaces seem to show more promising behaviour than vertical joints. It was confirmed that starting compaction from the hot side of the joint generally produces better results than compaction starting from the cold side of the joint. Pre-heating of the joint surface and using a bond sealant appears to provide the best results.

Keywords
cold asphalt pavement joints, asphalt joint laboratory production, IDT joint evaluation, DTT joint evaluation, 4PB joint evaluation, joints FE analysis
National Category
Infrastructure Engineering
Research subject
SRA - Transport
Identifiers
urn:nbn:se:kth:diva-134179 (URN)10.1080/14680629.2013.812979 (DOI)000330015900002 ()2-s2.0-84888129020 (Scopus ID)
Note

QC 20140122

Available from: 2013-11-18 Created: 2013-11-18 Last updated: 2017-12-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5526-5896

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