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| 2. |
- Ahmed, Abubeker W., 1981-, et al.
(författare)
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Characterization of heavy traffic axle load spectra for mechanistic-empirical pavement design applications
- 2015
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Ingår i: The international journal of pavement engineering. - : Taylor & Francis Group. - 1029-8436 .- 1477-268X. ; 16:6, s. 488-501
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Tidskriftsartikel (refereegranskat)abstract
- Heavy traffic axle load spectrum (ALS) is one of the key inputs for mechanistic-empirical analysis and design of pavement structures. Frequently, the entire ALS is aggregated into Equivalent Number of Single Axle Loads (ESAL) or assumed to have Constant Contact Area (CCA) or Constant Contact Pressure (CCP). These characterizations affect the accuracy and computational performance of the pavement analysis. The objective of this study was to evaluate these characterizations based on predicted performances to rutting and fatigue cracking of several pavement structures subjected to ALS data collected from 12 Bridge-Weigh-In-Motion stations. The results indicated that for layers below the top 25 cm, all characterizations produced similar values of predicted rutting. However, for the top 25 cm, the methods differed in the predicted performances to rutting and fatigue cracking. Furthermore an improvement to the CCA approach was proposed that enhanced the accuracy while maintaining the same level of computational performance.
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| 3. |
- Ahmed, Abubeker W., 1981-, et al.
(författare)
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Numerical validation of viscoelastic responses of a pavement structure in a full-scale accelerated pavement test
- 2015
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Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X.
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Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates the application of a generalised layered linear viscoelastic (LVE) analysis for estimating the structural response of flexible pavements. A comparison of the direct layered viscoelastic responses with approximate solutions based on the linear elastic (LE) and LVE collocation methods was also carried out. The different approaches were implemented by extending a layered elastic program with an improved computational performance. The LE and LVE collocation methods were further extended for analysis of pavements under moving loads.The methods were illustrated by analysing a pavement structure subjected to moving wheel loads of 30, 50, 60 and 80 kN using a Heavy Vehicle Simulator (HVS). The various responses (stresses and strains) in the pavement, at pavement temperatures of 0, 10 and 20°C, were measured using various types of sensors installed in the structure. It was shown that the approximated LVE solution based on the LE collocation method agreed very well with the measurements and is computationally the least expensive.
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| 4. |
- 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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| 5. |
- Alzubaidi, H., et al.
(författare)
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Statistical Analysis of Gravel Road Rating
- 2002
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Ingår i: The international journal of pavement engineering. - Nottingham. - 1029-8436 .- 1477-268X. ; 3:1, s. 35-42
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Bagampadde, Umaru, et al.
(författare)
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Influence of aggregate chemical and mineralogical composition on stripping in bituminous mixtures
- 2005
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Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 6:4, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- The influence of aggregate chemical and mineralogical composition on moisture sensitivity was investigated using 11 aggregates from typical tropical and temperate climates and one bitumen. Mix design and compaction were based on Swedish Road 94 hot mix base specifications and moisture damage was determined using resilient modulus and tensile strength ratios. As much as practically possible, air voids, gradation, compaction level, bitumen content and curing were controlled. Mixtures from aggregates containing sodium and potassium exhibited relatively high moisture sensitivity. The converse was apparent for aggregates with calcium, magnesium and iron. No significant correlation was observed between the strength ratios and contents of Al2O3 and SiO2. Stripping was generally high for aggregates with quartz and alkali feldspars, although one aggregate with practically 100% quartz showed low moisture sensitivity. Statistical analysis showed good correlation between resilient modulus and tensile strength ratios.
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| 7. |
- Biligiri, Krishna Prapoorna, et al.
(författare)
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Understanding the fundamental material properties of low-noise poroelastic road surfaces
- 2013
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Ingår i: The international journal of pavement engineering. - : Taylor & Francis. - 1029-8436 .- 1477-268X. ; 14:1, s. 12-23
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this study was to characterise the fundamental material (stiffness) properties of the poroelastic road surfaces (PERS) relevant to the pavement design. The research encompassed preparation of five variants of PERS mixtures in the laboratory based on the combinations of rubber, aggregate and binder components. Two standard test procedures were utilised: stress–strain sweep test and dynamic modulus E* test. First, stress–strain sweep test was performed at 1 mm/min strain rate to investigate the PERS mixtures' elastic characteristics. Hysteresis loops were plotted between force and strain change, which indicated that in all the mixes, the samples were stable to resist against higher hysteresis losses during successive cycles of testing. Also, lower losses were observed with increasing rubber contents; the results can be used in optimising the rubber content in the PERS to further assess rolling resistance and friction. Next, dynamic modulus E* test was performed on the PERS. The dynamic moduli varied based on the blending of rubber and aggregates proportion; the PERS mixes with higher amount of aggregates and lower amount of rubber had higher moduli. A comparison of moduli between the PERS mixtures and a typical asphalt concrete (AC) mix indicated that the PERS were softer than the AC mix by about 20–1500 times; the softness characteristics of the PERS would plausibly provide higher noise-dampening response. The methods employed so far covered stress–strain, and stiffness characteristics, which could be used in pavement design and the evaluation of rolling resistance and noise-reducing properties. Although this study is just a portion of a much more comprehensive laboratory test programme, these tests along with the upcoming laboratory tests are envisaged to aid in selecting the most promising PERS materials for the application on trafficked roads
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| 8. |
- Birgisson, Björn, et al.
(författare)
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Characterisation of asphalt mixture cracking behaviour using the three-point bending beam test
- 2011
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Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 12:6, s. 569-578
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Tidskriftsartikel (refereegranskat)abstract
- The use of a three-point bending beam (3PB) test was investigated to characterise hot mix asphalt (HMA) cracking behaviour. Fundamental HMA fracture properties, identified as tensile strength and fracture energy density at first fracture, were determined for six different asphalt mixtures (two natural and four SBS polymer modified) applying the HMA Fracture Mechanics framework. Full-field strain maps obtained from an in-house developed digital image correlation-based method were observed to better understand the crack initiation and propagation mechanisms in the 3PB specimen. The resulting fracture behaviour was predicted using a displacement discontinuity boundary element method to model the microstructure of the six asphalt mixtures and to predict their fracture properties. Both numerical and experimental results indicate that the fracture mechanism of asphalt mixtures can be properly described from 3PB test results when appropriate interpretation models are used.
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| 9. |
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| 10. |
- Butt, Ali Azhar, 1984-, et al.
(författare)
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Life Cycle Assessment Framework for Asphalt Pavements : Methods to Calculate and Allocate Energy of Binder and Additives
- 2014
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Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 15:4, s. 290-302
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Tidskriftsartikel (refereegranskat)abstract
- The construction, maintenance and disposal of asphalt pavements may lead to considerable environmental impacts, in terms of energy use and emissions during the life of the pavement. In order to enable quantification of the potential environmental impacts due to construction, maintenance and disposal of roads, an open life cycle assessment (LCA) framework for the asphalt pavements is presented in this paper. Emphasis was placed on the calculation and allocation of energy used for binder and additives at the project level. It was concluded from this study that when progressing from LCA to its corresponding life cycle cost, the feedstock energy of the binder becomes highly relevant as the cost of the binder will be reflected in its alternative value as fuel. Regarding additives like wax, a framework for energy allocation was suggested. The suggested project level LCA framework was demonstrated in a limited case study of a Swedish asphalt pavement. It was concluded that the asphalt production and transporting materials were the two most energy-consuming processes, emitting most greenhouse gases depending on the fuel type and electricity mix.
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