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Packing theory-based framework to evaluate permanent deformation of unbound granular materials
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.ORCID iD: 0000-0003-0889-6078
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.ORCID iD: 0000-0002-0596-228X
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
2013 (English)In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 14, no 3, 309-320 p.Article in journal (Refereed) Published
Abstract [en]

Permanent deformation of unbound granular materials plays an essential role in the long-term performance of a pavement structure. Stability of unbound granular materials is defined by the particle-to-particle contact of the system, the particle size distribution and the packing arrangement. This paper presents a gradation model based on packing theory to evaluate permanent deformation of unbound granular materials. The framework was evaluated by using 10 unbound granular materials from different countries. The disruption potential, which determines the ability of secondary structure (SS) to disrupt the primary structure (PS), is introduced. This study also identified the amount of PS and SS that may eventually be used as a design parameter for permanent deformation of unbound road layers. The evaluation of the model regarding permanent deformation behaviour of granular materials is found to compare favourably with experimental results.

Place, publisher, year, edition, pages
Taylor & Francis, 2013. Vol. 14, no 3, 309-320 p.
Keyword [en]
gradation, unbound materials, packing theory, primary structure, secondary structure, disruption potential, permanent deformation
National Category
Civil Engineering
Identifiers
URN: urn:nbn:se:kth:diva-97750DOI: 10.1080/10298436.2012.736620ISI: 000322305800008Scopus ID: 2-s2.0-84873576997OAI: oai:DiVA.org:kth-97750DiVA: diva2:533656
Note

QC 20150625. Updated from submitted to published.

Available from: 2012-06-14 Created: 2012-06-14 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Performance model for unbound grnular materials pavements
Open this publication in new window or tab >>Performance model for unbound grnular materials pavements
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Recently, there has been growing interest on the behaviour of unbound granular material in road base layers. Researchers have studied that the design of a new pavement and prediction of service life need proper characterization of unbound granular materials, which is one of the requirements for a new mechanistic design method in flexible pavement.

Adequate knowledge of the strength and deformation characteristics of unbound layer in pavements is a prerequisite for proper thickness design, residual life determination, and overall economic optimization of the pavement structure. The current knowledge concerning the granular materials employed in pavement structures is limited. In addition, to date, no general framework has been established to explain satisfactorily the behaviour of unbound granular materials under the complex repeated loading which they experience.

In this study, a conceptual method, packing theory-based model is introduced; this framework evaluates the stability and performance of granular materials based on their packing arrangement. In the framework two basic aggregate structures named as Primary Structure (PS), and Secondary Structure (SS). The Primary Structure (PS) is a range of interactive grain sizes that forms the network of unbound granular materials. The Secondary Structure (SS) includes granular materials smaller than the primary structure. The Secondary Structures fill the gaps between the particles in the Primary Structure and larger particles essentially float in the skeleton.

In this particular packing theory-based model; the Primary Structure porosity, the average contact points (coordination number) of Primary Structure, and a new parameter named Disruption Potential are the key parameters that determine whether or not a particular gradation results in a suitable aggregate structure.

Parameters mentioned above play major role in the aggregate skeleton to perform well in terms of resistance to permanent deformation as well as load carrying capacity (resilient modulus). The skeleton of the materials must be composed of both coarse enough and a limited amount of fine granular materials to effectively resist deformation and carry traffic loads.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xiii, 18 p.
Series
Trita-TSC-LIC, 12-004
Keyword
unbound granular materials, aggregate, packing theory, gradation, primary structure, secundary structure, permanent deformation, resilient modulus
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-97752 (URN)978-91-85539-89-5 (ISBN)
Presentation
2012-06-01, B26, KTH, Brinellvägen 23, Stockholm, 09:00 (English)
Opponent
Supervisors
Note
QC 20120601Available from: 2012-06-14 Created: 2012-06-14Bibliographically approved
2. Packing theory-based Framework for Performance Evaluation of Unbound Granular Materials
Open this publication in new window or tab >>Packing theory-based Framework for Performance Evaluation of Unbound Granular Materials
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Enhancing the load bearing quality of granular layers is fundamental to optimize the structural performance of the pavements. Unbound granular materials are one of the most used materials in the base layers of pavements. There have been growing interests on the behavior of unbound granular material in road base layers. Both design of a new pavement and prediction of service life need proper characterization of unbound granular materials, which is one of the requirements for a new mechanistic pavement design methods.

Adequate knowledge of the strength and deformation characteristics of unbound layers in pavements is essential for proper thickness design, residual life determination, and economic optimization of the pavement structure. The current knowledge concerning granular materials employed in pavement structures is limited. In addition, to date, no general framework has been established to explain and evaluate satisfactorily the behavior of unbound granular materials under the complex repeated loading which they experience.

This thesis presents a packing theory-based framework to evaluate the mechanical properties of unbound granular materials. The framework was developed based on the particle-to-particle contact, the particle size distribution and the packing arrangement. The skeleton of the unbound materials should be composed of both coarse enough particles and a limited amount of fine granular materials to effectively resist deformation and carry traffic loads. Based on this, the framework identifies the two basic components of unbound granular materials, namely the primary structure (PS) - a range of interactive coarse grain sizes that forms the main load carrying network in granular materials and the secondary structure (SS) - a range of grain sizes smaller than the PS providing stability to the aggregate skeleton.

In the framework, disruption potential (DP), PS porosity, PS coordination number and void ratio of skeleton (PS+SS) are among the key packing parameters which were established from the framework. These parameters were validated by evaluating the permanent deformation, resilient modulus and California bearing ratio of unbound granular materials using different materials with various experimental results.

Furthermore, in this thesis a new moisture distribution model (Birgisson-Jelagin-Yideti (BJY) moisture distribution model) was introduced. In the model, SS particles associated with water retention. The water is stored as meniscus water between these small particles and fully filled in small voids. The volume of meniscus water between SS particles and the measured matric suction values are the two key parameters considered in the model. The results showed that the model developed is capable of predicting the experimentally measured matric suction values for a range of gradations.

Finally, the application of shakedown and packing theories to characterize permanent deformation behaviour of unbound aggregate materials is presented. A simple finite element analysis has also been simulated in order to find out the effect of disruption potential on the shakedown limit load. Experimental results were used for the simulation of the finite element and compared favourably with the predicted mean stress and dimensionless shakedown load using DP values.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. viii, 60 p.
Series
TRITA-TSC-PHD, 14:001
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-143487 (URN)978-91-87353-36-9 (ISBN)
Public defence
2014-04-11, Kollegiesalen (the old chapel), Brinellvägen 8, KTH, Stockholm, 09:30 (English)
Opponent
Supervisors
Note

QC 20140324

Available from: 2014-03-24 Created: 2014-03-21 Last updated: 2014-03-25Bibliographically approved

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Birgisson, BjörnJelagin, Denis

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