| 1. |
- Ahmed, Abubeker W, 1981-, et al.
(författare)
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Pavement performance follow-up and evaluation of polymer-modified test sections
- 2019
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Ingår i: The international journal of pavement engineering. - : Taylor and Francis Ltd.. - 1029-8436 .- 1477-268X. ; 20:12, s. 1474-1487
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Tidskriftsartikel (refereegranskat)abstract
- Between 2003 and 2006, a test road consisting of several conventional and polymer-modified structures was built on a motorway. Different combinations of styrene–butadiene–styrene (SBS) and ethyl vinyl acetate (EVA) polymer-modified binders were used. The test structures have been in service since then and have been monitored for over 9 years. The resistance of the different types of asphalt concrete mixes to rutting and cracking was measured and predicted. The impact of ageing on the mixes was also evaluated. Although all the sections are in good condition after 9 years of traffic, the predicted differences between the test sections based on the PEDRO (Permanent Deformation of asphalt concrete layers for Roads) approach and laboratory evaluations are noticeable. Lateral wander and transverse profile measurements indicated that studded winter tyre wear contributed to most of the rutting compared to permanent deformation due to heavy traffic. The unmodified mixes exhibited considerable ageing and the SBS-modified mixes were least affected by ageing. Furthermore, the SBS-modified base mix produced significantly better fatigue resistance than the conventional base mix. However, further investigations of the relationships between bitumen and mix properties and further follow-ups of the test sections are recommended to validate the findings.
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| 2. |
- Erlingsson, Sigurdur, 1960-, et al.
(författare)
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Mechanistic rutting modelling of a LTPP road structure
- 2019
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Ingår i: Pavement and Asset Management. - : CRC Press/Balkema. - 9780367209896 ; , s. 241-249
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Konferensbidrag (refereegranskat)abstract
- A new Mechanistic-Empirical (M-E) approach is under development to predict the structural degradation of road structures as a function of time. The aim is that the method will become one of the backbones in a new pavement asset management system. The calculation scheme is based two main steps; i) a response calculation step for the different traffic loads applied taking into account the ambient climate and ii) a performance prediction step where pavement degradation is predicted in time steps and thereafter accumulated over the entire design period of the pavement structure. The paper describes the approach briefly and is thereafter demonstrated by a calculation of the degradation of an arterial road in Southern Sweden and compared with measurements from the Swedish Long Term Pavement Performance (LTPP) database. The arterial road had reached the critical 15 mm rut after 18 years in operation. The analysis shows that the rutting development can be simulated adequately although the calculations show slower rate than the measurements towards the end of the simulated period.
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| 3. |
- Gudmarsson, Anders, et al.
(författare)
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Precision of modal analysis to characterise the complex modulus of asphalt concrete
- 2019
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Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor & Francis. - 1468-0629 .- 2164-7402. ; 20:sup 1, s. S217-S232
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Tidskriftsartikel (refereegranskat)abstract
- Modal analysis is an economic and efficient test method to characterise the complex modulus of asphalt concrete. In this paper, the precision of modal analysis was evaluated by performing testing at several laboratories on two cylindrical asphalt concrete specimens. In addition, the complex moduli characterised by modal analysis were compared to cyclic tension-compression testing. The results showed that the coefficient of variation was less than 3% at loading frequencies above 10 Hz for the complex modulus determined through modal analysis. The comparison of the complex modulus determined from modal analysis and tension-compression testing resulted in a coefficient of variation values not more than 9% for loading frequencies ranging from 0.1 to 10 9 Hz.
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| 4. |
- Lindelöf, Peter, et al.
(författare)
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Poisson’s Ratio of Asphalt Concrete Mixes Using Indirect Tensile Test
- 2019
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Ingår i: Journal of Testing and Evaluation. - : ASME Press. - 0090-3973 .- 1945-7553. ; 47:1, s. 498-510
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Tidskriftsartikel (refereegranskat)abstract
- Increased interest in mechanistic evaluation of flexible pavement structures has brought a demand for accurate and practical methods, models, or both to estimate the mechanical properties of asphalt concrete mixtures. One of these properties is the Poisson’s ratio (ν) of asphalt concrete mixtures, which is often assumed to have a constant value of 0.35 in asphalt concrete evaluations. However, investigations have reported that mixture type, air void content, and temperature produce considerable variation in measured ν-values that could have a significant effect on evaluations of asphalt concrete mixes. The objective of this study was to evaluate the effect of air voids, binder type, and testing conditions on the measured ν-values. Indirect tensile (IDT) tests were conducted to measure ν-values. The study indicated that the Poisson’s ratio of the asphalt concrete mixes, on average, attained a maximum value at a particular level of air void content. Furthermore, when comparing the Poisson’s ratio values in relation to the dynamic modulus, calculated using the Mechanistic Empirical Pavement Design Guide (MEPDG) equation, higher ν-values were attained. This demonstrates the importance of measuring the Poisson’s ratio of a mix type.
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| 5. |
- Sulejmani, Pajtim, et al.
(författare)
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Moisture Sensitivity of Asphalt Mixtures using Cycling Pore Pressure Conditioning
- 2019
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Ingår i: Transportation Research Record. - : Sage Publications. - 0361-1981 .- 2169-4052. ; 2673:2, s. 294-303
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Tidskriftsartikel (refereegranskat)abstract
- One of the major causes of premature failure in asphalt pavements is moisture damage. Asphalt mixtures designed without considering climate impacts may suffer from durability problems caused by movement of water inside the asphalt mixture. Rolling traffic over wet pavement builds up pore pressure in the mixture, which will consequently accelerate deterioration. The objective of the study was to assess the moisture damage to asphalt concrete mixtures by means of complex modulus testing of dry and moisture-conditioned asphalt specimens with various mixture compositions. The asphalt mixtures were conditioned with the Moisture Induced Sensitivity Tester (MIST), which aims to replicate pore pressure in field conditions. The results showed a decline in stiffness modulus and a reduction in elastic properties after MIST conditioning. In addition, the results indicated that binder content and air void content had a significant influence on the reduction in stiffness. To capture the relationship between air void content, binder content, and the reduction in stiffness, a relationship was developed and validated with measurements on cores extracted in the field.
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