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  • 1.
    Ahmed, Abubeker
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Hellman, Fredrik
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Full scale accelerated pavement tests to evaluate the performance of permeable and skeletal soil block pavement systems2016In: The Roles of Accelerated Pavement Testing in Pavement Sustainability: Engineering, Environment, and Economics, Springer International Publishing , 2016, p. 131-144Chapter in book (Other academic)
    Abstract [en]

    The increasing proportion of paved surface due to urbanization means that the conditions for urban trees and vegetation to survive have deteriorated. Factors such as air pollution, poor drainage, and the lack of usable soil for root growth contribute to the short life expectancy of urban trees. To meet this challenge, several permeable and "structural" or "skeletal soils" have been developed as alternatives to the typical compacted soil required to bear the weight of vehicular traffic in urban areas. The main objective of this study is to evaluate the resistance to permanent deformation of permeable and skeletal soil pavement structures based on full scale accelerated pavement tests (APT) using a heavy vehicle simulator (HVS). Interlocking paving stones of various types were used as permeable surface layer for the test structures. The results demonstrated that the permeable test structures exhibited higher permanent deformation than the corresponding impervious structures. The skeletal soil with bituminous base layer, however, produced performance comparable to the impervious reference test structures.

  • 2.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Characterization of heavy traffic axle load spectra for mechanistic-empirical pavement design applications2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 16, no 6, p. 488-501Article in journal (Refereed)
    Abstract [en]

     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.

  • 3.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Evaluation of a permanent deformation model for asphalt concrete mixtures using extra-large wheel-tracking and heavy vehicle simulator tests2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, no 1, p. 154-171Article in journal (Refereed)
    Abstract [en]

    This paper evaluates a mechanistic–empirical permanent strain model for asphalt concrete mixtures. The evaluation was carried out based on two different types of tests: an extra-large wheel-tracking (ELWT) test and a full-scale accelerated pavement test using a heavy vehicle simulator (HVS). Asphalt slabs from three different types of asphalt mixtures were prepared for the ELWT test and tested at several pavement temperatures and tyre inflation pressures. Lateral wandering was also incorporated.

    The measured permanent deformations in the asphalt slabs were thereafter modelled using the permanent strain model from the US Mechanistic-Empirical Pavement Design Guide and model parameters were estimated for the three types of mixes. For validation, data from an HVS tested pavement structure consisting of the same asphalt mixtures as those tested using the ELWT were used. A set of calibration factors for the three mixtures were therefore obtained between the two tests. In all cases, the calibration factors were within ±20% from unity. Differences in geometry, scale, wheel loading configuration as well as the speed of loading between the two test devices could be the possible reasons for the differences in observed calibration factors.

  • 4.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Evaluation of permanent deformation model for asphalt concrete mixtures by means of extra-large wheel tracking and full scale accelerated pavement testsManuscript (preprint) (Other academic)
  • 5.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Evaluation of permanent deformation models for unbound granular materials using accelerated pavement tests2013In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no 1, p. 178-195Article in journal (Refereed)
    Abstract [en]

    Mechanistic-empirical (M-E) pavement design methods have become the focus of modern pavement design procedure. One of the main distresses that M-E design methods attempt to control is permanent deformation (rutting). The objective of this paper is to evaluate three M-E permanent deformation models for unbound granular materials, one from the US M-E pavement design guide and two other relatively new models. Two series of heavy vehicle simulator (HVS) tests with three different types of base material were used for this purpose. The permanent deformation, wheel loading, pavement temperature, and other material properties were continuously controlled during the HVS tests. Asphalt concrete layers were considered as linear elastic where stress-dependent behaviour of unbound materials was considered when computing responses for the M-E permanent deformation models with a nonlinear elastic response model. Traffic wandering was also accounted for in modelling the traffic by assuming it was normally distributed and a time-hardening approach was applied to add together the permanent deformation contributions from different stress levels. The measured and predicted permanent deformations are in general in good agreement with only small discrepancies between the models. Model parameters were also estimated for three different types of material.

  • 6.
    Ahmed, Abubeker W
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Mechanistic modelling of HVS flexible pavement structure2012In: EPAM 2012: Malmö, Sweden, 5–7 September: 4th European pavement and asset management conference, Linköping: Statens väg- och transportforskningsinstitut, 2012, , p. 13Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    A response model to be employed in a mechanistic-empirical pavement performance prediction model based on multilayer elastic theory has been developed. An iterative approach using a method of successive over-relaxation of stress dependency model is used to account for the nonlinear behaviour of unbound materials. Asphalt and subgrade materials are assumed as linear elastic. The response model is verified using heavy vehicle simulator (HVS) response measurements made under variety of wheel load configurations and at different pavement temperatures. The permanent deformation behaviours of the HVS structure is also modelled using mechanistic empirical approach and by employing permanent deformation prediction models. A time hardening approach has been applied to combine permanent deformation contributions from stress levels of different magnitude. The response model outputs and the predicted permanent deformations are in general in good agreement with the measurements.

  • 7.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Modeling of flexible pavement structure behavior: Comparisons with Heavy Vehicle Simulator measurements2012In: Advances in Pavement Design Through Full-Scale Accelerated Pavement Testing / [ed] Jones, Harvey, Mateos & Al-Qadi, London: Taylor & Francis Group, 2012, p. 493-503Conference paper (Refereed)
    Abstract [en]

     A response model to be employed in a mechanistic-empirical pavement performance predictionmodel based on multilayer elastic theory has been developed. An iterative approach using a method of successiveover-relaxation of a stress dependency model is used to account for the nonlinear behavior of unbound materials. Asphalt and subgrade materials are assumed to be linear elastic. The response model was verified against two series of Heavy Vehicle Simulator (HVS) response measurements made under a variety of wheel loadconfigurations and at different pavement temperatures. A comparison with Falling Weight Deflectometer (FWD)data was also carried out. The model was subsequently used to predict permanent deformation from the HVS testing using simple work hardening models. A time hardening approach has been adopted to combine permanentdeformation contributions from stress levels of different magnitude.The response model outputs and the predictedpermanent deformations were generally in good agreement with the measurements.

  • 8.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Numerical validation of viscoelastic responses of a pavement structure in a full-scale accelerated pavement test2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed)
    Abstract [en]

    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.

  • 9.
    Ahmed, Abubeker W.
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Viscoelastic modelling of pavement structure behaviour in a full scale accelerated pavement testManuscript (preprint) (Other academic)
  • 10.
    Ahmed, Abubeker W
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Viscoelastic Response Modelling of a Pavement under Moving Load2016In: Transportation Research Procedia, 2016, Vol. 14, p. 748-757Conference paper (Refereed)
    Abstract [en]

    This paper demonstrates the application of a generalized layered linear viscoelastic (LVE) analysis for estimating flexible pavements' structural response. The procedure is based on the Multi-Layered Elastic Theory (MLET) and the elastic-viscoelastic correspondence principle using a numerical inverse Laplace transform. A comparison of the direct layered viscoelastic responses with approximate solutions based on the elastic collocation method was also carried out. Furthermore, it is proposed to use the collocation method using LVE solutions at selected time durations in order to improve the accuracy of the elastic collocation method. The LVE collocation method was further extended for analysis of moving loads. The method was 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 different pavement temperatures, were measured using various types of sensors installed in the structure. The LVE calculations agreed very well with the measurements.

  • 11.
    Ahmed, Abubeker W
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Rahman, Mohammad Shafiqur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Impact of longer and heavier vehicles on the performance of asphalt pavements: A laboratory study2018In: 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. 483-490Conference paper (Refereed)
    Abstract [en]

    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.

  • 12.
    Ahmed, Abubeker W
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Rahman, Mohammad Shafiqur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Impact of tire types and configurations on responses of a thin pavement structure2018In: Advances in Materials and Pavement Performance Prediction: Proceedings of the International AM3P Conference, 2018, London: CRC Press , 2018, p. 271-274Conference paper (Refereed)
    Abstract [en]

    The objective of this study was to assess the impact of tire and tire configurations on the responses of a thin asphalt pavement structure by means of full-scale tests using a Heavy Vehicle Simulator (HVS). A total of six different types of tires, four single and two dual tire configurations, were investigated. The structure was instrumented to measure tensile strains at the bottom of the asphalt layer and vertical stresses and strains in the unbound base, subbase and subgrade layers. The results indicated that, in general, single tire configurations produced higher tensile strain at the bottom of the asphalt layer and higher vertical stresses and strains in unbound base, subbase and subgrade layers.

  • 13.
    Arvidsson, Anna K
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Blomqvist, Göran
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Hellman, Fredrik
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Jägerbrand, Annika
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Öberg, Gudrun
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Klimatanpassning av vägkonstruktion, drift och underhåll2012Report (Other academic)
    Abstract [en]

    The global climate change is a reality and affecting society and transport systems. Climate change adaptation of transport systems will make the means of transportation more resilient and decrease the risk and magnitude of disruptions. Generally, climate change adaptations in road construction, operation and maintenance will need relatively large changes, but there is a shortage of the specific knowledge required as to what steps need to be taken, when and where, before measures can actually be implemented. Since climate change effects vary among Sweden's climatic zones, the impact of climate change on the road behavior and longevity is extremely difficult to predict. The need for winter maintenance in Sweden will generally decrease due to the warmer climate. Ploughing frequency will probably decrease as well, but preparedness should not be reduced too much since occasions with more extreme instances will increase. In order to succeed in making the road transport system resilient to climate change, we conclude that there is a need to develop more knowledge about the impact on the road infrastructure system as well as the operation and maintenance of the system including how to adapt through different types of variable and flexible climate adaptation measures and the effects of extreme weather events.

  • 14.
    Canon Falla, Gustavo
    et al.
    Technische Universitat Dresden.
    Leischner, S.
    Technische Universitat Dresden.
    Blasl, A.
    Technische Universitat Dresden.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Characterization of unbound granular materials within a mechanistic design framework for low volume roads2017In: Transportation Geotechnics, ISSN 2214-3912, Vol. 13, p. 2-12Article in journal (Refereed)
    Abstract [en]

    Unbound granular materials (UGM), used in base and subbase layers, play a major role in the structural performance of low volume roads (LVR) with a thin asphalt surface layer. A prerequisite for a proper design of such roads is the development of reliable testing techniques to simulate the behavior of UGMs under conditions similar to those that occur when subjected to traffic. Therefore, there is a need for simple and economical test methods to characterize the mechanical behavior of UGM under the action of high traffic loads. This paper presents a methodology for the experimental characterization of UGMs with a focus on mechanistic design. The results of a test campaign aimed at characterizing the elastic and plastic behavior of UGM are shown. The laboratory tests were performed using a new volumetric compaction tests and the triaxial test. Based on the results of the tests, a new classification method for UGMs intended to be used in the base course of thin asphalt pavements is suggested. 

  • 15.
    Dolk, Ellen
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Silfwerbrand, Johan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Concrete pavement Falkenberg, Sweden: a 20 year review2016Conference paper (Refereed)
    Abstract [en]

    The majority of the road network in Sweden consists of flexible pavements. Only a small fraction is rigid pavements and the most recent concrete structure was built ten years ago. This creates a problem as the national experience and knowledge in terms of design and maintenance of rigid pavements is not maintained. It is therefore important to gather and adequately document the performance of existing concrete structures.

    One such structure is along the motorway E6 close to Falkenberg on the southwest coast of Sweden built in 1993-1996. The structure is a 28 km long Jointed Plain Concrete Pavement (JPCP) resting on a cement-treated base. The climate in the area consists of a typical coastal climate with high precipitation and short, relatively warm summers and relatively cold winters with a high number of zero degree changes. Studded tire wear, normally contributing to a large extent to the total rut on the Swedish road network, is only 5 mm after these 20 years. However, the structure is suffering from longitudinal cracking along the outer wheel track that is thought to have been caused by the combined effects of erosion within the cement-treated base, resulting in cavities under the concrete slabs and the fact that the dowel bars are placed too low and thus reducing the load transfer mechanism between the slabs and acting as crack inducers.

  • 16.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Characterization of heavy traffic on the Swedish road network2010In: 11th International Conference on Asphalt Pavements 2010: ISAP Nagoya 2010, Tokyo: International Society for Asphalt Pavements, ISAP , 2010, , p. 8p. 1704-1711Conference paper (Other academic)
    Abstract [en]

    One of the key parameters in predicting the deterioration process of pavement structures is linked to the heavy traffic characteristics. The heavy traffic loading has been commonly expressed in pavement design methods through an equivalent number of repetitions of standard axle loads (ESAL’s). Recent pavement distress models, used in new mechanistic pavement design methods, require more detailed description of the heavy traffic. In Sweden, a Bridge Weigh-In-Motion (BWIM) system has been used to collect information about the heavy traffic on the road network. The system provides information about the vehicles’ time of passing, speed and lane, the number of axles and their configurations and weights. A national BWIM network was established in 2004, consisting of twelve locations which are measured during one week every year. The network consists of motorways, arterials or trunk roads as well as one county road. This, therefore, provides a basis to establish an Axle Load Spectra (ALS) which gives the load distribution of steering axles, other single axles, tandem and tridem axles. As very few quad axles are registered they have been neglected.

  • 17.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute.
    Impact of Water on the Response and Performance of a Pavement Structure in an Accelerated Test2010In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 11, no 4, p. 863-880Article in journal (Refereed)
    Abstract [en]

    An accelerated load test using a Heavy Vehicle Simulator (HVS) was performed with the objective of investigating the response behaviour and performance of a commonly used pavement structure in Sweden. The structure consists of 10 cm asphalt bound layers, divided into surface course and bitumen base, over granular base and subbase resting on sandy subgrade. The structure was instrumented to register stresses, strains and deflections during loading.

    In the test more than 1,000,000 load cycles were applied. After applying the first 500,000 load cycles the water table was raised and a further 500,000 loading cycles were applied. Raising the groundwater table increased the rate of rutting developed in the structure in all unbound layers. A numerical analysis has been carried out to simulate the results.

    First the response was simulated to get a general overall agreement of the pavement response and the parameters of the model. Thereafter the permanent deformation behaviour in the main test was simulated using a simple three-parameter work hardening model with two sets of parameters for the unbound layers, before and after the groundwater table was raised. The permanent deformation behaviour of all layers was thereafter modelled separately for the two steps.

    Generally good agreement was established between the permanent deformation measurements and the calculations for all layers.

  • 18.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Impact of water on the structural performance of pavements2010In: The 11th international conference on asphalt pavements 2010: ISAP Nagoya 2010, Tokyo: International Society for Asphalt Pavements, ISAP , 2010, , p. 10p. 542-551Conference paper (Other academic)
    Abstract [en]

    An accelerated load test has been performed at VTI’s test facility in Sweden using a Heavy Vehicle Simulator (HVS). The objective was to investigate the response behaviour and performance of a commonly used flexible pavement structure in Sweden. The instrumented structure was built in a concrete test pit and consists of 10 cm bounded layer, a granular base and a subbase resting on sandy subgrade. The test was divided into three phases: a pre-loading phase, a response phase and the main accelerated loading test where 1,000,000 load cycles were applied. After the preloading phase 500,000 load cycles were applied and then the water table was raised and further 500,000 loading cycles were applied. Raising the groundwater table increased the rate of rutting developed in all unbound layers. From the sensor registrations it is clearly seen that the stiffness of all unbound layers decreased as the water table was raised, thus the pressure cells revealed lower registrations but the vertical strain gauges increased their readings. Further, it was observed that the rate of accumulation of permanent deformation accelerated. This has been interpreted as the impact of higher water content on the characteristics of the unbound layers, the subgrade, subbase and base course.

  • 19.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Mechanistic performance modelling of rutting in pavement structures2012In: EPAM 2012: Malmö, Sweden, 5–7 September: 4th European pavement and asset management conference / [ed] Gustafson, Kent, Linköping: Statens väg- och transportforskningsinstitut, 2012, , p. 10Conference paper (Other academic)
    Abstract [en]

    A mechanistic empirical (M–E) approach has been developed and thereafter used to calculate the degradation behaviour of two arterial roads in Southern Sweden. The results were then compared with measurements from the Swedish long term pavement performance (LTPP) database. The M-E approach used was a two-step procedure where the response of the structure was calculated mechanistically and thereafter the performance predicted empirically based on scaling of laboratory test results. Extensive laboratory testing was carried out on samples taken from the test roads. Traffic counting and Bridge Weigh-in-Motion data were used to determine the amount of traffic loading, and data from weather stations were used to take into account the temperature dependency of the asphalt bound layers. 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. The discrepancy in the rate of rutting between the measurements and the observations that was observed after about 9 years of operation might be due to the fact that no ageing or disintegration in material characterization was incorporated in the numerical analysis but surely observed in reality.

  • 20.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute. University of Iceland.
    Numerical Modelling of Thin Pavements Behaviour in Accelerated HVS Tests2007In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Road Materials and Pavement Design, ISSN 1468-0629, Vol. 8, no 4, p. 719-744Article in journal (Refereed)
    Abstract [en]

    Two thin road structures have been tested in accelerated testing by using a Heavy Vehicle Simulator (HVS). Both were surface dressed structures, one with a target 20 cm thick unbound base course layer and the other with the base divided into a 10 cm bitumen stabilized base over 10 cm unbound base. The tested road structures were instrumented to estimate deflections, strains and stresses in various locations inside the structure.

    Numerical analyses, by using two different techniques, the multilayer elastic theory (MLET) and the finite element (FE) have been carried out to simulate the response behaviour of the tested structure and compared with the actual measurements. For both techniques linear and nonlinear behaviour of the base was assumed. For the FE method both 2D axisymmetric and a 3D analysis were carried out. The results have further been used to model the permanent deformation development in each layer. The main finding of the study was that induced vertical stresses were generally well predicted in both structures. Better agreement was generally found between the vertical stresses and the actual response with the non-linear response, especially for high loading conditions.

    The best prediction of surface deflections was obtained in a three dimensional linear elastic analysis where a rectangular loading area was used instead of a circular one in the two dimensional axisymmetric solutions. Generally, poor or moderate agreement was found between the strain measurements and the numerical estimations. The simple work hardening model used to model the accumulated deformation relied on results from repeated load triaxial test results and gave generally good agreement with the results from the testing.

  • 21.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute. University of Iceland.
    On Forecasting the Resilient Modulus from the CBR Value of Granular Bases2007In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 8, no 4, p. 783-797Article in journal (Refereed)
    Abstract [en]

    The unbound granular materials (UGM), base and subbase layers, play an essential role in the overall structural performance of thin pavement structures. They show complex stress dependent elasto-plastic behaviour under external loading. Therefore the UGM are commonly tested using the Repeated Load Triaxial (RLT) testing method to estimate the stiffness of the material by applying haversine loading pulses.

    The RLT testing method represents the actual stress situation quite adequately and gives satisfactorily estimates of the stiffness characteristics of UGM. A simple test that has been used for a long time in structural design of flexible pavements is the CBR (California Bearing Ratio) test. In the CBR test, the load-deformation curve is acquired while a plunger is penetrated into the material at a constant rate. In the literature one can find a number of relationships for UGM where the CBR value is used to predict the stiffness. These connections usually do not take into account that stiffness of UGM is both stress and moisture dependent.

    To investigate if a relationship between the two tests exists, twenty materials have been tested with both methods and the test results compared. The materials were of varying quality and were tested at four different moisture contents. The results indicate that a simple power law can be used to forecast the stiffness if the CBR-value is known.

  • 22.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Tunga trafikens samhällsekonomiska kostnader: accelererade tester av tre vägkonstruktioner2017Report (Other academic)
    Abstract [en]

    The Swedish Ministry of Enterprise and Innovation (Näringsdepartementet) has given VTI the assignment to update the knowledge about the society costs of the transport infrastructure. A part of that work is to improve our knowledge about the relationship between traffic axle loads and degradations of pavement structures.

    The objective of this report is to investigate if a simple relationship between axle loading and pavements degradation can be used as a tool for estimation of marginal costs for degradation of the entire road network. Three full scale test pavement structures have therefore been tested with an Heavy Vehicle Simulator using three half-axle load levels 40, 50 and 60 kN (corresponding to 8, 10 and 12 tonnes axle loads) to investigate the load intensity on the degradation progress. As a measure of the distress development has the linear rutting rate during testing been used after the initial exponential rutting phase was passed.

  • 23.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Ahmed, Abubeker
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    The Svappavaara road test sections: field coring and laboratory tests2015Report (Other academic)
    Abstract [en]

    This report describes laboratory testing of specimens taken from four new instrumented test road sections that have been built on E45 close to the Svappavaara municipality in Norrbotten County in Northern Sweden. The structures are located about 100 km north of the Arctic Circle in a climate that is characterized by long cold winters and short mild summers. The four test sections were built in a conventional manner. Each structure is about 200–250-metre-long with a central 100-metre-long part defined as the actual test section. All structures are in total 60 centimetres in thickness resting on top of a 70-centimetre-thick old existing road. The bitumen bound part of all the four structures consists of four layers; a thin surface course layer, two binder layers and a road base layer. All structures have the same wearing course, TSK 16 with a standard 160/220 penetration grade bitumen. The main difference between the structures lies in the binder as well as the two road base layers. As a part of the monitoring programme drilled asphalt specimens were taken in 2013 from the road structure and tested at VTI's material testing laboratory in Linköping. Furthermore, samples were taken from the unbound base course and tested. This report presents the test results for asphalt bound layers as well as for the unbound base course. For the bound layers the testing procedure included volumetric properties, stiffness modulus and fatigue tests for the different types of conventional and polymer modified asphalt mixtures. The tests were conducted in accordance with the Swedish or the equivalent European standards. For the unbound base course fundamental properties were estimated as well as stiffness and permanent deformation properties for different moisture contents.

  • 24.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Ahmed, Abubeker W.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Fast layered elastic response program for the analysis of flexible pavement structures2013In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no 1, p. 196-210Article in journal (Refereed)
    Abstract [en]

    One of the key components in analysing pavement structural behaviour is the response model which is used to estimate the stresses, strains and displacements of the pavement structure subjected to the existing traffic, taking into account the material properties and prevailing environmental conditions. Multilayer elastic theory (MLET) is often preferred over other methods such as the finite element method, due to its computational performance for repeated applications. A new elastic response analysis program has been developed based on the Burmister MLET theory to calculate the response of flexible pavement structures. In the development of the program, the time-consuming part of MLET processes was optimised. To improve the convergence and accuracy of responses in the vicinity of the surface of the top layer, an approach based on Richardson's extrapolation was employed. Moreover, an iterative approach to model stress dependency of unbound granular materials was incorporated. A comprehensive comparison of the program with two frequently used programs demonstrated an excellent agreement and improved performance.

  • 25.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Ahmed, Abubeker W
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Mechanistic rutting modelling of a LTPP road structure2019In: Pavement and Asset Management: Proceedings of the World Conference on Pavement and Asset Management, WCPAM 2017, CRC Press/Balkema , 2019, p. 241-249Conference paper (Refereed)
    Abstract [en]

    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.

  • 26.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Carlsson, Håkan
    Swedish National Road and Transport Research Institute, Infrastructure, Measurement technology and engineering workshop.
    Testplatser för 74 ton tunga fordon: två instrumenterade tunna vägkonstruktioner2018Report (Other academic)
    Abstract [en]

    This VTI note describes briefly the construction and instrumentation of two new test road structures that have been built during the autumn 2017 on Lv373 and Lv515 respectively in Norrbotten County in northern Sweden. One structure is placed on Lv373 east of the village Långträsk while the other structure is on Lv515 south if the intersection with Lv373. The distance between the two locations is about 10 km. Both structures are thin pavement structures. The main objective of the two new test sites is to estimate the impact that the new 74 tonnes vehicles have on the Swedish road network. This will be done through direct measurements of the pavement response from the road sensors. The sensors consist of horizontal strain sensors in both longitudinal and transversal direction at the bottom of the asphalt layer as well as vertical strain sensors over every layer down to 1.2 m depth. Soil pressure cells are further installed at two depths. The local ambient climate is monitored as well. A frost and a moisture rod were therefore installed. Further are temperature sensors installed in the asphalt concrete. Two weather stations are located within 20 km distances from the test structures. The first response measurements are planned in the late summer or early autumn 2018.

  • 27.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Carlsson, Håkan
    Swedish National Road and Transport Research Institute, Infrastructure, Measurement technology and engineering workshop.
    The Svappavaara road test sections: instrumentation2014Report (Other academic)
    Abstract [en]

    This report describes four new instrumented test road sections that have been built on E45 close to the Svappavaara in Norrbotten County in Northern Sweden. The structures are located about 100 km north of the Arctic Circle in a climate that is characterized by long cold winters and short mild summers. Norrbotten County is a sparsely populated area where the pavement structures consist of thin pavements with relatively low traffic volume. A new ore deposit, the Kaunisvaara project, was opened in 2012, meaning that the ore will be transported along the existing road network about 160 kilometers to where it will be transferred to a railway. The ore operator has received a permit to use 90 ton vehicles instead of the permissible 60 tons, consisting of a single wheel steering axle and triple dual wheel tridem axles to transport the iron ore. When the ore processing will be in full operation around 66.000 journeys per year will pass over the network, or on average about 7–8 passes per hour with about seven and a half minutes between the passes. Due to this new ore transport it will be necessary to strengthen the local road network. As part of the process to evaluate the performance of a suitable pavement structure these four instrumented test road structures have been selected and built. The structures are instrumented with road performance and climate sensors. The structures will be monitored over the years to come, though the details of the monitoring programme have not yet been decided. Each test section is around 200 metres long, consisting of a 100 metres long inner part that constitutes the intrinsic test section. The structures were built and instrumented in the summer of 2012 except for the wearing course that was placed in the summer of 2013 along with the temperature sensors that are placed in the asphalt layers. The instrumentation in each section consists of Emu coils for vertical strain measurement devices, soil pressure cells for vertical stress measurements and tensile strain gauges located at the bottom of the bound road base layer. In addition there are moisture rods located in three of the structures and a temperature (frost) rod located in structure 3. A weather station (2527 Svappavaara) operated by the Transport Administration is located 3.2 kilometre south-east of the test site.

  • 28.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Olafsdottir, Elin Asta
    University of Iceland.
    Bessason, Bjarni
    University of Iceland.
    Stiffness of sandy sites using the Multichannel Analysis of Surface Waves method2017In: ICSMGE 2017: 19th International Conference on Soil Mechanics and Geotechnical Engineering, 19th ICSMGE Secretariat , 2017, p. 593-597Conference paper (Refereed)
    Abstract [en]

    Multichannel Analysis of Surface Waves (MASW) is seismic exploration method to evaluate shear wave velocity profiles of near-surface soil materials based on analysis of horizontally travelling Rayleigh waves. The MASW method has been applied at four loose sandy sites in South Iceland providing shear wave velocity (VS) profiles for the uppermost 25 m at each site. The VS-profile obtained for one of the test sites was compared to empirical profiles estimated on the bases of CPT measurements carried out at the site. The results indicate that the MASW profile corresponds adequately well to the empirical estimations, strengthening the results obtained by MASW. However, further comparison of MASW and CPT data is needed in order to evaluate the overall applicability of existing CPT-VS correlations at Icelandic sand sites.

  • 29.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Rahman, Mohammad Shafiqur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. KTH.
    Evaluation of permanent deformation characteristics of unbound granular materials from multi-stage repeated load triaxial test2013In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2369, p. 17p. 11-19Article in journal (Refereed)
    Abstract [en]

    Rutting in flexible pavements is often associated with permanent deformation of the unbound granular layer. The current permanent deformation models are only applicable to a single stress path in repeated load triaxial (RLT) tests. In this paper, a simple approach using the time hardening concept was introduced to continuously model the permanent deformation of unbound granular materials (UGM) in multi-stage (MS) repeated load triaxial (RLT) tests. Three existing permanent deformation models were reconstructed to be implemented with this method and one model was slightly modified to better suit this approach. This approach was validated by calibrating these reconstructed models using data from MS RLT tests on three different UGM used in base layers of flexible pavement structures. The calibrations were done by optimizing the material parameters of the models using least square curve fitting method. The shakedown ranges were also calculated for each stress path of the MS RLT tests to compare these models in simulating these ranges. Generally, very good fits were obtained for these models where the modified model showed the best agreement.

  • 30.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Rahman, Mohammad Shafiqur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Salour, Farhad
    Trafikverket.
    Characteristic of unbound granular materials and subgrades based on multi stage RLT testing2017In: Transportation Geotechnics, ISSN 2214-3912, Vol. 13, p. 28-42Article in journal (Refereed)
    Abstract [en]

    The unbound granular layers (UGM's) and the subgrade of a pavement structure provide a significant support for the structure as a whole. Hence the mechanical properties of these materials are important for the overall performance of the structure. These materials exhibit both non-linear stress dependency and their mechanical properties are highly affected by their moisture content. This paper describes two of the most important material properties of the unbound layers of the pavements, i.e. the resilient and the permanent deformation properties. The stress dependency of UGMs can be captured by the universal model or the enhanced model by Cary and Zapata (2011) for materials with high fine content. The Bishop's effective stress approach can be used for high fine content materials for estimating the effect of suction. UGMs and subgrade materials are further highly dependent on moisture content. Either the AASHTO sigmoidal model can be used to describe the moisture dependency or the simple exponential model described in this paper. The paper further discusses four models to characterize the accumulation of permanent deformation with the number of load repetitions in repeated load triaxial (RLT) testing. The models are all developed to fit single stage (SS) RLT test results but have been extended to fit multi-stage (MS) RLT test results with the aid of the time hardening scheme. The advantage of the MS RLT tests over the SS RLT tests is that it applies a range of stress paths on a single specimen, thus taking into account the effect of stress history and reducing the time and effort required to test a separate specimen for each stress path.

  • 31.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Said, Safwat
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    McGarvey, Terry
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Influence of heavy traffic lateral wander on pavement deterioration2012In: EPAM 2012: Malmö, Sweden, 5–7 September : 4th European pavement and asset management conference, Linköping: Statens väg- och transportforskningsinstitut, 2012, , p. 11Conference paper (Other academic)
    Abstract [en]

    Lateral wander of the traffic has an impact on the degradation development of pavements. This is usually not accounted for in the structural design process. Facilities with wide carriageways and broad shoulders tends to have relatively large lateral spreading while narrow road facilities lacking any shoulders can have highly channelized traffic pattern. In this research lateral wander characteristics have been measured for different road facilities. They can be assumed follow a normal distribution where the standard deviation describes their lateral spreading. Rut depth has thereafter been estimated according to two new rutting calculation scheme where lateral wander characteristics has been taken into account. The first approach is based on a two step mechanistic empirical (M-E) evaluation of the permanent strain in all layer of the structure and using a time hardening approach to sum up for all wander locations. This has thereafter been used to estimate the difference in rutting development as a function of the standard deviation. The second approach concentrates on calculating the permanent strain visco-elastically in the bound layers of the structure. Both procedures can be used to estimate the rate of relative deterioration for different road facilities. Based on the same structure the first approach give around 6 % increase in the surface rut as the standard deviation of the lateral wander increases from 10 to 20 cm. The second approach estimates this difference to be around 20 %. The difference between the two approaches are partly explained due to that the first approach estimates the rut based on all layers but the second approach from the bound layers only.

  • 32.
    Erlingsson, Sigurdur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Ullberg, J.
    Trafikverket.
    Responses and performance of flexible pavements in cold climate due to heavy vehicle loading2018In: 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. 451-457Conference paper (Refereed)
    Abstract [en]

    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.

  • 33.
    Franzén, Gunilla
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Lindh, Per
    PEAB.
    Åhnberg, Helen
    SGI.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Terrasstabilisering: kunskapsdokument2012Report (Other academic)
    Abstract [en]

    In situ stabilisation of sub-grade is a method used in order to improve the bearing capacity in foundations on fine-grained soils with low bearing capacity. The method is applied in order to improve the bearing capacity for, for example, temporary roads during construction, but mainly for optimizing the pavement of the final road. The method is commonly used outside of Sweden and has proved to give well-functioning constructions.

    The aim of the study has been to compile existing knowledge of the possibilities and limitations of the method to create opportunities for an increased use. The document deals with in situ stabilisation of existing fine-grained soil. Stabilization of the unbound layers in the road construction itself is not included in the study. Since the main purpose has been to study the method itself, the focus has been on traditional binders such as lime, concrete and slag. Some of the findings:

    • In order to use the full potential of the method it is necessary to further develop execution practice and requirements.
    • •The financial advantages of the method are mainly notable considering the life-cycle costs instead of investment costs.
    • •Under certain circumstances, the method has a potential to contribute to energy efficiency.
  • 34.
    Lundberg, Joacim
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment. KTH.
    Janhäll, Sara
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Gustafsson, Mats
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. KTH.
    Calibration of the Swedish Studdded Tyre Abrasion Wear Prediction Model and the Implication for the NORTRIP Road Dust Emission Model2018In: Transportation Research Board 97th annual meeting, Washington, D.C., 2018Conference paper (Refereed)
    Abstract [en]

    An experimentally based prediction model of rut development due to studded tyres is available in Sweden and which had been found to work well. However, since it has not been validated since 2007, during which traffic as well as road and tyre design have developed, the question has arisen regarding the model’s current validity. Also, since the prediction model is used in the NORTRIP (NOn-exhaust Road Traffic Induced Particle emission) emission model, a natural question is how a change in the wear model will affect the emission model. In this paper, two versions of the abrasion model are compared to measurements at several recently constructed roads in Sweden to investigate the validity, while also proposing changes to allow for continued use. In addition, the impact on NORTRIP is briefly investigated. The paper first describes the abrasion models and their calibration, as well as the test sections for calibration. Both versions of the model, as expected, overestimated the wear and an update was suggested. It was also found that NORTRIP is indicatively affected by overestimating the contribution of pavement wear to the emissions.

  • 35.
    Lundberg, Joacim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. VTI - Statens Väg- och Transportforskningsinstitut.
    Janhäll, Sara
    VTI - Statens Väg- och Transportforskningsinstitut.
    Gustafsson, Mats
    VTI - Statens Väg- och Transportforskningsinstitut.
    Erlingsson, Sigurdur
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. VTI - Statens Väg- och Transportforskningsinstitut / Islands Universitet.
    Calibration of the Swedish Studded Tyre Abrasion Wear Prediction Model and the Implication for the NORTRIP Road Dust Emission Model2018In: Transportation Research Board 97th annual meeting, Washington, D.C., 2018Conference paper (Refereed)
    Abstract [en]

    An experimentally based prediction model of rut development due to studded tyres is available in 3 Sweden and which had been found to work well. However, since it has not been validated since 4 2007, during which traffic as well as road and tyre design have developed, the question has 5 arisen regarding the model’s current validity. Also, since the prediction model is used in the 6 NORTRIP (NOn-exhaust Road Traffic Induced Particle emission) emission model, a natural 7 question is how a change in the wear model will affect the emission model. In this paper, two 8 versions of the abrasion model are compared to measurements at several recently constructed 9 roads in Sweden to investigate the validity, while also proposing changes to allow for continued 10 use. In addition, the impact on NORTRIP is briefly investigated. The paper first describes the 11 abrasion models and their calibration, as well as the test sections for calibration. Both versions of 12 the model, as expected, overestimated the wear and an update was suggested. It was also found 13 that NORTRIP is indicatively affected by overestimating the contribution of pavement wear to 14 the emissions.

  • 36.
    Lundberg, Joacim
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Janhäll, Sara
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Gustafsson, Mats
    Swedish National Road and Transport Research Institute, Society, environment and transport, Enviroment and traffic analysis.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Calibration of the Swedish studded tyre abrasion wear prediction model with implication for the NORTRIP road dust emission model2019In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed)
    Abstract [en]

    An experimentally based prediction model of road abrasion wear due to studded tyres is available in Sweden and has been found to work well. However, it has not been validated since 2007, and since then road surfaces and tyre design have developed, and the question has arisen regarding the model’s current validity. The abrasion wear model is used in the NORTRIP emission model (NOn-exhaust Road Traffic Induced Particle emission modelling), and the effect of a recalibrated abrasion wear model on the emission model is shown. In this paper, the abrasion wear model is compared to full-scale field measurements at several recently constructed roads in Sweden to investigate its validity, while also proposing changes to allow for continued use. It is concluded that the model overestimates the wear and an update is suggested. In addition, the impact on NORTRIP emission predictions is briefly investigated. There were also indications that NORTRIP is affected by the abrasion model overestimating the contribution of pavement wear to the particle emissions.

  • 37.
    Olafsdottir, Elin Asta
    et al.
    University of Iceland.
    Bessason, Bjarna
    University of Iceland.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Combination of dispersion curves from MASW measurements2018In: Soil Dynamics and Earthquake Engineering, ISSN 0267-7261, E-ISSN 1879-341X, Vol. 113, p. 473-487Article in journal (Refereed)
    Abstract [en]

    Multichannel analysis of surface waves (MASW) is a seismic exploration method for determination of near-surface shear wave velocity profiles based on analysis of horizontally travelling Rayleigh waves. This paper aims to propose a methodology and recommendations for combining dispersion data from several multichannel records. The dispersion curves are added up within logarithmically spaced wavelength intervals and the uncertainty of the mean phase velocity estimates is evaluated by using classical statistics and the bootstrap. The results indicate that combining multiple dispersion curves, which have been gathered by receiver spreads of different lengths (but with the same midpoint), can increase the investigation depth of the survey, improve its resolution at shallow depth and overall improve the reliability of the results as compared to the use of a single record. Moreover, the uncertainty of the combined mean dispersion curve can be determined and further used to present the shear wave velocity profile with upper and lower boundaries.

  • 38.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    A model for predicting permanent deformation of unbound granular materials2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, no 3, p. 653-673Article in journal (Refereed)
    Abstract [en]

    A simple model has been proposed to characterise the accumulation of permanent deformation (PD) in unbound granular materials (UGMs) under cyclic loading of variable magnitudes. The model was developed based on multi-stage (MS) repeated-load triaxial (RLT) tests. The material parameters of this model can be evaluated using an MS RLT test. The model was validated by calibrating it for a few UGMs with a range of grain size distributions, moisture contents and degrees of compaction.

    The calibrated model was further validated by predicting the PD behaviour of some of these UGMs for different stress conditions. Generally, quite satisfactory predictions were obtained with this model with the advantage of reduced effort required for its calibration compared to some existing models. Additionally, the sensitivity of the parameters of this model to moisture, degree of compaction and grain size distribution was investigated with the aim of incorporating them into the model in future.

  • 39.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Influence of moisture on Resilient Deformation behaviour of Unbound Granular Materials2014In: Asphalt Pavements: Proceedings of the International Conference on Asphalt Pavements, ISAP 2014, 2014, p. 571-580Conference paper (Refereed)
    Abstract [en]

    This study investigated the influence of moisture on the Resilient Deformation (RD) properties of Unbound Granular Materials (UGMs). A typical UGM used in pavement constructions with three different grain size distributions were tested with a range of moisture contents using Repeated Load Triaxial tests (RLTTs). From the European standard, the procedure for the study of the RD behaviour was used where each stress path is applied for 100 cycles. Additionally, the Multi-Stage (MS) loading procedure for the study of the permanent deformation behaviour were used where each stress path is applied for 10,000 cycles, to compare the results using the two test procedures. Results showed that resilient modulus (MR) generally decreased with increase in moisture, where the finer grading was more affected. However, for the MS RLTTs, after a large number of load applications, some increase in MR with increasing moisture was observed. This happened when the moisture content increased up to close to the optimum; above the optimum, MR always decreased. This may be due to Post-Compaction (PC) aided by moisture in MS RLTTs where a large number of load cycles were applied.

  • 40.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Influence of post compaction on the moisture sensitive resilient modulus of unbound granular materials2016In: Procedia Engineering, Elsevier, 2016, p. 929-936Conference paper (Refereed)
    Abstract [en]

    The impact of moisture on the resilient modulus (MR) of unbound granular materials (UGMs) was investigated based on repeated load triaxial (RLT) tests and considering the effect of post compaction (PC) from cyclic loading. Results showed that although MR decreases with increased moisture, it may appear to increase with increased moisture if the PC process is aided by moisture for a relatively large number of load applications. When limited PC was involved, the parameter k1 of the k-θ model decreased with increased moisture while the parameter k2 was unaffected. On the other hand, when significant amount of PC took place, k2 increased with increased moisture.

    The mechanistic-empirical pavement design guide (MEPDG) model worked well to capture the influence of moisture on the stiffness when MR decreased with increased moisture. However, it did not work when MR increased with increased moisture due to the PC effect. On the other hand, an alternative approach expressing k1 and k2 as functions of moisture worked well for both situations. Generally, this study suggested that the effect of PC should be considered in modelling the impact of moisture on MR for better accuracy.

  • 41.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Modelling the moisture dependent permanent deformation behavior of unbound granular materials2016In: Procedia Engineering, Elsevier, 2016, p. 921-928Conference paper (Refereed)
    Abstract [en]

    The impact of moisture on the permanent deformation (PD) behavior of unbound granular materials (UGMs) was investigated based on multistage (MS) repeated load triaxial (RLT) tests. Two UGMs with different particle size distributions were tested for a range of moisture contents and the accumulation of permanent strains for the different moisture contents were modelled using a simple predictive model.

    Moisture was found to increase the accumulation of PD in the materials. Analyses of the variation of the parameters of the model with respect to moisture showed that it is possible to capture the moisture dependent PD behavior of the materials assuming a simple linear relationship between one of the parameters of the model and the moisture content.

  • 42.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Moisture influence on the resilient deformation behaviour of unbound granular materials2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed)
    Abstract [en]

    The influence of moisture on the resilient deformation properties of unbound granular materials was investigated based on repeated load triaxial tests. Results showed that the resilient modulus (MR) decreased with increasing moisture for a relatively low number of load cycles (N) where the deformation behaviour was mostly resilient with a negligible amount of associated accumulated permanent deformation (PD). Modelling attempts on this behaviour were quite satisfactory.

    Furthermore, the MR showed an increasing trend with increasing moisture, up to the optimum, when the N was relatively large with a significant amount of accumulated PD. Above the optimum, the MR generally decreased. Further investigation suggested that moisture aided the post-compaction (PC) and possible particle rearrangement that resulted in the increased PD and increased MR. The existing model did not work in this case indicating that the effect of PC on MR should be considered in modelling.

  • 43.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. Kungliga Tekniska Högskolan.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Predicting permanent deformation behaviour of unbound granular materials2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 16, no 7, p. 587-601Article in journal (Refereed)
    Abstract [en]

    To reliably predict the permanent deformation behaviour of unbound granular materials (UGM) in a pavement structure, the material parameters of the constitutive models used in design should be evaluated using a multi-stage (MS) loading approach. This paper investigated the prediction of the accumulation of permanent strain in UGM using some current models, extended applying the time-hardening approach, based on MS repeated load triaxial tests (RLTTs).

    The material parameters of these models were optimised for five different UGM used in pavement construction using the MS RLTT data with a specific set of stress levels. With these models, the accumulations of permanent strain in the same materials for MS RLTTs with a different set of stress levels were predicted. Using this approach, three out of the four models performed very well, which may be further developed for field conditions for better prediction of rutting.

  • 44.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Hellman, Fredrik
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Stiffness and permanent deformation characteristics of open-graded unbound granular materials2018In: 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. 151-157Conference paper (Refereed)
    Abstract [en]

    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.

  • 45.
    Rahman, Mohammad Shafiqur
    et al.
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Hellman, Fredrik
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Investigation of the permanent deformation properties of open-graded permeable unbound granular materials2019In: Pavement and Asset Management - Proceedings of the World Conference on Pavement and Asset Management, WCPAM 2017, CRC Press/Balkema , 2019, p. 105-114Conference paper (Refereed)
    Abstract [en]

    Open-Graded (OG) Unbound Granular Materials (UGMs) are generally used in permeable pavement constructions. In this study, the Permanent Deformation (PD) characteristics of two OG UGMs were investigated by means of Multistage (MS) Repeated- Load Triaxial (RLT) tests. The influence of moisture on the PD behavior was also investigated. Compared to a few standard UGMs, these OG UMGs exhibited slightly lower resistance against PD in relatively dry state. On the other hand, these materials were less sensitive to moisture. Therefore, at higher moisture content, the OG UGMs and the standard UGMs showed identical PD behavior. Furthermore, the accumulation of PD was modelled using a simple model which may be used for prediction of rutting, estimating bearing capacity, and for layer thickness design, using a suitable pavement design software.

  • 46. Rahman, Shafiqur
    et al.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Moisture sensitivity of unbound granular materials2012In: EPAM 2012: Malmö, Sweden, 5–7 September: 4th European pavement and asset management conference / [ed] Kent Gustafson, Linköping: Statens väg- och transportforskningsinstitut, 2012, , p. 12Conference paper (Other academic)
    Abstract [en]

    One of the main structural units in thin flexible pavement is the unbound aggregate base course. It contributes to the overall load spreading mechanism of the structure due to traffic loading and provides an underneath support to the asphalt concrete layer. The material characteristic of unbound layers are therefore of great importance for the performance of the structure. Unbound base courses show stress as well as moisture dependent behaviour during external loading. This is true for both their stiffness and resistance against permanent deformation properties. A series of Repeated Load Triaxial (RLT) tests has been carried out on a typical unbound aggregate base layer to investigate its behaviour in order to improve the modelling of the moisture sensitivity. Both the resilient test and multi-stage loading approach have been used providing information on the resilient as well as the permanent deformation characteristics. Results showed that the stiffness decreases and permanent deformation increases with increasing moisture content.

  • 47.
    Saevarsdottir, Thorbjorg
    et al.
    University of Iceland.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Deformation Modelling of Instrumented Flexible Pavement Structure2016In: Procedia Engineering, 2016, p. 937-944Conference paper (Refereed)
    Abstract [en]

    A flexible test road structure was built and tested in an Accelerated Pavement Test (APT) using a Heavy Vehicle Simulator (HVS) to monitor its performance behaviour. In the tests more than one million load cycles were applied, but mid-way the water table was raised, allowing the structure to be analysed in "moist" and "wet" state. The raised water level had a significant effect, decreasing the resilient modulus and increasing the rate of accumulation of permanent deformation (PD). The structure was instrumented to measure stress, strain and deflection responses as a function of load repetitions as well as PD manifested on the surface as rutting. The structure has been modelled in an axisymmetric analysis using a 2D multi layer elastic theory (MLET) as well as a 3D finite element method (FEM).

    The methods generally both agreed well with the measurements. The observed accumulation of PD of the unbound layers was modelled using three different material models, both stress and strain based with responses gained from both MLET and FEM. The modelled deformation, is compared to the measured deformation in both "moist" and "wet" state, with some difference observed between models and methods but generally reasonably agreement was established.

  • 48.
    Saevarsdottir, Thorbjorg
    et al.
    University of Iceland.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Modelling of responses and rutting profile of a flexible pavement structure in a heavy vehicle simulator test2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, no 1, p. 1-18Article in journal (Refereed)
    Abstract [en]

    A flexible test road structure was tested in a heavy vehicle simulator test to monitor its performance behaviour. Water was added to the structure half-way through the test. The raised water level had a significant effect, decreasing the resilient modulus and increasing the rate of accumulation of permanent deformation. Numerical analyses to simulate the pavement responses have been carried out using both a two-dimensional multi-layer elastic method as well as three-dimensional finite element analysis, with material properties based on field and laboratory testing.

    Little difference was found between the two methods and both methods generally agreed well with the measurements. The observed accumulation of permanent deformation manifested on the surface as rutting was modelled using two simple work hardening material models; a stress-based model and a strain-based model. The stress-based model was found to be sensitive to slight response changes and had a closer fit than the strain-dependent model.

  • 49.
    Saevarsdottir, Thorbjorg
    et al.
    University of Iceland.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Water impact on the behaviour of flexible pavement structures in an accelerated test2013In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no 2, p. 256-277Article in journal (Refereed)
    Abstract [en]

    Two flexible test road structures were built and tested in an accelerated pavement test using a heavy vehicle simulator, with the aims of investigating their performance behaviour for a validation in a mechanistic performance scheme and the accuracy of repeated tests. In the test more than one million load cycles were applied, but after the first half million the water table was raised. The structures were therefore analysed in moist' and wet' states, before and after raising the water level. The increased water level had a significant effect on the structure with decreased resilient modulus and increased permanent deformation. Numerical analyses have been carried out to simulate the pavement responses, where the material properties used in the response analyses were based on field and laboratory testing. The observed accumulation of permanent deformation of the unbound layers was modelled using work hardening material models. Generally good agreement was established between the measurements and calculations.

  • 50.
    Saevarsdottir, Thorbjorg
    et al.
    University of Iceland.
    Erlingsson, Sigurdur
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology. University of Iceland.
    Carlsson, Håkan
    Swedish National Road and Transport Research Institute, Infrastructure, Measurement technology and engineering workshop.
    Heavy Vehicle Simulator tests at VTI2014In: Asphalt Pavements - Proceedings of the International Conference on Asphalt Pavements, ISAP 2014, 2014, p. 823-833Conference paper (Refereed)
    Abstract [en]

    Flexible test road structures have been built and tested in Accelerated Pavement Tests (APT) using a Heavy Vehicle Simulator (HVS) at VTI in Sweden for 15 years. The objectives have been to investigate pavement responses and pavement performance behaviour which can be used to validate mechanistic performance schemes. The pavement structures have been instrumented to measure their responses and performance and the surface profile was estimated.

    The accuracy of the measurements was estimated and a performance prediction was carried out. The registrations of the measurements were rather smooth with good repeatability and acceptable accuracy. The response, performance and accumulation of permanent deformation were modelled and generally good agreement was established between the measurements and calculations. From the analysis a performance prediction can be carried out as a function of time to evaluate the performance of new road concepts and maintenance strategies. The performance prediction provides the option of performing a life cycle cost analysis which can decrease both costs and environmental impacts.

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