| 1. |
- Ahmed, Abubeker W, 1981-, et al.
(författare)
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Impact of longer and heavier vehicles on the performance of asphalt pavements : A laboratory study
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 483-490
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Konferensbidrag (refereegranskat)abstract
- Historically, Longer and Heavier Vehicles (LHVs) have been permitted to operate in Sweden. Since 1996 and as of the beginning of 2015, the maximum gross vehicle weight of 60 tons and a length of up to 25.25 m have been permitted. The Swedish Transport Administration has decided to further increase the maximum gross vehicle weight to 74 tons and studies are undergoing to evaluate the impact of the proposed LHVs on existing transport infrastructure. To this end, repeated load triaxial tests and indirect tensile fatigue tests were conducted on selected conventional asphalt mixtures to investigate and quantify the impact of single, tandem and tridem axle configurations on permanent deformation and fatigue performances of conventional asphalt pavements. In addition, fatigue tests for selected LHV scenarios were conducted. This paper presents the results of the laboratory tests and simulations conducted. The test results have clearly demonstrated the impact of the different axle configurations on the rutting and fatigue performances of the mixture. Furthermore, such results can explain the significance of axle configuration on modelling the rutting and fatigue performances of asphalt pavements.
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| 2. |
- Erlingsson, Sigurdur, 1960-, et al.
(författare)
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Responses and performance of flexible pavements in cold climate due to heavy vehicle loading
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 451-457
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Konferensbidrag (refereegranskat)abstract
- Four instrumented test road structures have been built in northern Sweden about 100 km north of the Arctic Circle. The climate consists of cold winters and mild summers with a long spring thaw period. The pavement structures differs in material quality ranging from conventional to polymer modified structures. The objective of the test structures is to see the difference in their behaviour and performance due to the heavy loading in the ambient artic climate. Each test section is instrumented that includes pressure cells and strain sensors that measure the pavement response to external loading. Climatic variables are further monitored through a weather station as well as temperature and moisture sensors installed in the road structure. Response measurements have been carried out using 90 tons vehicles consisting of a single wheel steering axle, and triple dual wheel tridem axles. Rutting development has been monitored through four years showing some difference between the structures rutting development.
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| 3. |
- Ghafoori Roozbahany, Ehsan, 1982-, et al.
(författare)
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Influence of layer thickness on the flow of asphalt under simulated compaction
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 1435-1441
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 4. |
- Gudmarsson, A., et al.
(författare)
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Apps for modal analysis to characterize the complex modulus of asphalt concrete
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 209-215
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Konferensbidrag (refereegranskat)abstract
- The time and temperature dependent dynamic modulus of asphalt concrete is a key parameter to modern pavement design and to pavement quality. However, accurate measurements of the complex modulus through conventional cyclic testing are expensive regarding both time and costs. Novel test methods based on modal analysis facilitate economic, accurate and faster determination of linear viscoelastic material properties of asphalt concrete. The modal analysis is performed by using an impact hammer and an accelerometer to measure frequency response functions of asphalt concrete specimens with free boundary conditions. The complex modulus and complex Poisson’s ratio are determined by matching finite element computed frequency response functions to the measurements. This paper presents one software application to perform the modal testing and one application to compute and optimize frequency response functions to determine the complex modulus and complex Poisson’s ratio. The software applications greatly simplifies the methodology to determine material properties through modal analysis of asphalt concrete specimens.
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| 5. |
- Rahman, Mohammad Shafiqur, 1978-, et al.
(författare)
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Stiffness and permanent deformation characteristics of open-graded unbound granular materials
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 151-157
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Konferensbidrag (refereegranskat)abstract
- This paper presents the investigation of the deformation characteristics of two Open-Graded (OG) Unbound Granular Materials (UGMs) that are generally used in permeable pavement structures. Based on multistage Repeated-Load Triaxial (RLT) tests, the stiffness and resistance against Permanent Deformation (PD) of these materials were compared to their well graded (standard) counterparts. The OG UGMs showed similar stiffness characteristics as standard UGMs. On the other hand, the resistance against PD was slightly worse than the standard UGMs in a relatively dry state. However, the OG UGMs showed less sensitivity to moisture variation, yielding similar performance to that of standard materials at higher moisture content. The parameters of a stiffness model and a PD model were evaluated for these materials which may be used for prediction of rutting, estimating bearing capacity and for layer thickness design, using any suitable pavement design software.
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| 6. |
- Said, Safwat, 1951-, et al.
(författare)
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Prediction of heavy vehicle impact on rut development using pedro model
- 2018
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Ingår i: 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. - 9781138295957 ; , s. 1359-1366
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Konferensbidrag (refereegranskat)abstract
- Permanent deformation or flow rutting in bituminous layers is a common distress mode in flexible pavements that is exhibited as an excessive deformation of bituminous material in the wheel paths. Rutting gradually increases with repeated loading of heavy vehicles. To predict surface rutting, it is therefore essential to include the influence of heavy vehicle parameters such as the number of passages of wheel loads, axle load configuration (single or dual wheel), tire type, inflation pressure, vehicle speed and lateral wandering of the traffic in addition to variation in mixture properties at ambient temperatures over elapsed time. The linear viscoelastic permanent deformation model for a bituminous layer of roads, PEDRO, has been adopted in this work to analyse the vertical strain distribution in a flexible pavement and prediction of rutting under various combination of heavy vehicle parameters. The effects of heavy vehicles with different axle load configurations are evaluated with support of field measurements over a 14-year period.
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