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Evaluation of permanent deformation models for unbound granular materials using accelerated pavement tests
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
2013 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, Vol. 14, no 1, 178-195 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
2013. Vol. 14, no 1, 178-195 p.
Keyword [en]
rutting, unbound granular materials, stress dependency, traffic wandering, mechanistic empirical methods, response model, permanent deformation models
National Category
Other Civil Engineering
URN: urn:nbn:se:kth:diva-119728DOI: 10.1080/14680629.2012.755936ISI: 000315352600011ScopusID: 2-s2.0-84878253785OAI: diva2:612785

QC 20130325

Available from: 2013-03-25 Created: 2013-03-21 Last updated: 2014-05-12Bibliographically approved
In thesis
1. Mechanistic-Empirical Modelling of Flexible Pavement Performance: Verifications Using APT Measurements
Open this publication in new window or tab >>Mechanistic-Empirical Modelling of Flexible Pavement Performance: Verifications Using APT Measurements
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mechanistic-Empirical  (M-E)  pavement  design  procedures  are  composed  of  a  reliable  response model to estimate the state of stress in the pavement and distress models in order to predict the different types of pavement distresses due to the prevailing traffic and environmental conditions. One of the main objectives of this study was to develop a response model based on multilayer elastic  theory   (MLET)  with  improved  computational  performance  by   optimizing  the   time consuming parts of the MLET processes. A comprehensive comparison of the developed program with  two  widely  used  programs  demonstrated  excellent  agreement  and  improved  computational performance.  Moreover,  the  program  was  extended  to  incorporate  the  viscoelastic  behaviour  of bituminous materials through elastic-viscoelastic correspondence principle. A procedure based on collocation of linear viscoelastic (LVE) solutions at selected key time durations was also proposed that improved the computational performance for LVE analysis of stationary and moving loads. A comparison  of  the  LVE  responses  with  measurements  from  accelerated  pavement  testing  (APT) revealed a good agreement. Furthermore the developed response model was employed to evaluate permanent deformation models  for  bound  and  unbound  granular  materials  (UGMs)  using  full  scale  APTs.  The  M-E Pavement  Design  Guide  (MEPDG)  model  for  UGMs  and  two  relatively  new  models  were evaluated  to  model  the  permanent  deformation  in  UGMs.  Moreover,  for  bound  materials,  the simplified  form  of  the  MEPDG  model  for  bituminous  bound  layers  was  also  evaluated.  The measured  and  predicted  permanent  deformations  were  in  general  in  good  agreement,  with  only small discrepancies between the models. Finally, as heavy traffic loading is one of the main factors affecting the performance of flexible pavement, three types of characterizations for heavy traffic axle load spectrum for M-E analysis and design of pavement structures were evaluated. The study recommended an improved approach that enhanced the accuracy and computational performance. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 60 p.
Flexible Pavement; Pavement Performance Models; Multilayer Elastic Theory; Linear Viscoelasticity; Rutting; Accelerated Pavement Testing; Heavy Vehicle Simulator
National Category
Infrastructure Engineering
Research subject
Transport Science; Civil and Architectural Engineering
urn:nbn:se:kth:diva-145136 (URN)978-91-87353-39-0 (ISBN)
Public defence
2014-05-23, Q2, Osquldas väg 10, KTH, Stockholm, 13:30 (English)

QC 20140512

Available from: 2014-05-12 Created: 2014-05-12 Last updated: 2014-05-19Bibliographically approved

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Ahmed, Abubeker W.
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