Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Investigation of the asphalt mixture morphology influence on its ageing susceptibility
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.ORCID-id: 0000-0003-0889-6078
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.ORCID-id: 0000-0002-0596-228X
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.ORCID-id: 0000-0003-3968-6778
2015 (Engelska)Ingår i: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, nr 4, s. 987-1000Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The main objective of this study is to investigate the influence that asphalt mixture morphology aspects have on its overall ageing behavior. Since mixture morphology is controllable, having insight into how the various morphological parameters influence the mixture’s long-term behavior can be of great value to optimize its design, regardless of the individual material properties. To do so, this study is utilizing a new framework to characterize the combined effect of aggregate packing, average air void size, porosity and level of compaction on ageing for a large set of data from different sources of field compacted and laboratory produced asphalt mixtures. The paper also hypothesizes about the mechanisms that lay behind the found influences and how thus mixture design improvements can be made. From all the investigated cases, it was found that the framework can be used to optimize the durability performance of asphalt mixtures. It was also observed that prediction of ageing behavior without considering the influence of mixture morphology may lead to erroneous conclusions and non-optimal mix design.

Ort, förlag, år, upplaga, sidor
2015. Vol. 48, nr 4, s. 987-1000
Nyckelord [en]
Ageing, Asphalt mixture morphology, Gradation, Average air void size, Aggregate packing
Nationell ämneskategori
Samhällsbyggnadsteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-145050DOI: 10.1617/s11527-013-0209-zISI: 000350889100014Scopus ID: 2-s2.0-84924220970OAI: oai:DiVA.org:kth-145050DiVA, id: diva2:715942
Anmärkning

QP 201406

Tillgänglig från: 2014-05-07 Skapad: 2014-05-07 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
Ingår i avhandling
1. Ageing of Asphalt Mixtures: Micro-scale and mixture morphology investigation
Öppna denna publikation i ny flik eller fönster >>Ageing of Asphalt Mixtures: Micro-scale and mixture morphology investigation
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

There are many variables that affect the viscoelastic properties of asphalt mixtures with time, among which age hardening may be considered one of the important ones. Age hardening of asphalt mixtures is an irreversible process, which contributes to a reduction of the durability of pavements and eventually increases the maintenance cost. Beside the environmental effects, ageing in asphalt mixture depends on the physicochemical properties of bitumen and mixture morphology which is a combined effect of aggregate packing, porosity, air void distribution and their interconnectivity. Thus, a clear understanding on the physicochemical properties of bitumen and mixture morphology may help to predict the performance of asphalt mixtures, which will contribute to longer-lasting and better performing pavements.

When looking at the bitumen at micro-scale, one can see microstructures appearing under certain conditions which can be partially explained by the interaction of the individual phases. Since the thermo-rheological behavior of bitumen depends largely on its chemical structure and intermolecular microstructures, studying these can lead to understanding of the mechanism, speed and conditions under which this phase behavior occurs. Linking this to the changes in properties of bitumen can thus lead to better understanding of the causes of ageing, its dominant parameters and the resulting diminished mechanical response.

To investigate ageing in asphalt pavements, along with physicochemical properties of bitumen one needs to also focus on the influence of mixture morphology.  It is known that asphalt mixtures with similar percentages of air-voids can have different morphologies and thus can age differently. Prediction of ageing behavior without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. Hence, it is important to understand the interplay between the mixture morphology and ageing susceptibility and relate this to the long term mixture performance.

The aim of this Thesis was to develop fundamental understanding on ageing in asphalt mixtures that can contribute to the asphalt community moving away from the currently used accelerated ageing laboratory tests and empirical models that can lead to erroneous conclusions.

To reach this aim, experimental and numerical micro-scale analyses on bitumen and meso-scale investigations on mixture morphology have been performed which, collectively, allowed for the development of a method for the prediction of asphalt field ageing, incorporating both mixture morphology and micro-scale bitumen mechanisms. For this, first, the mechanisms of surface ageing and diffusion controlled oxidative ageing were identified. Secondly, the influence of mixture morphology on asphalt ageing susceptibility was investigated. Procedures to determine the controlling parameter were then developed and an empirical framework to quantify the long-term field ageing of asphalt mixtures was set-up. For this, a combination of experimental and numerical methods was employed.

An extensive experimental study was carried out to understand the fundamental mechanisms behind the micro-structural phase appearance and the speed or mobility at which they change. Atomic Force Microscopy (AFM) was utilized at different temperatures to investigate the phase separation behavior for four different types of bitumen and co-relate it with the Differential Scanning Calorimetry (DSC) measurements. Based on the experimental findings, it was concluded that the observed phase separation is mainly due to the wax/paraffin fraction presence in bitumen (Paper I). A hypothesis was developed of the appearance of a thin film at the specimen surface due to ageing which is creating a barrier, restricting thus the microstructures to float towards the surface. Furthermore, investigation showed that depending on the bitumen and exposure types this surface thin film is water soluble and thus the moisture damage becomes more severe with the ageing of asphalt pavement (Paper II and IV).

A new empirical relation to obtain the primary structure coating thickness was established utilizing mixture volumetric properties and gradation using a large set of data from different literature sources. It was found that the enhanced morphological framework can be used to optimize the long term performance of asphalt mixtures (Paper III).  Thereafter, the effect of diffusion controlled oxidative ageing on different mixture morphologies based on oxidative ageing mechanism of bitumen and diffusion-reaction process was investigated using the Finite Element Method (FEM). From the FE analyses, the effect of air-void distribution and their interconnectivity combined with the aggregate packing was shown to have a significant effect on age hardening (Paper IV).

It was shown that focusing only on the percentage of air-void as the main predictive ageing parameter may lead to an erroneous conclusion and non-optimal predictions of long-term behavior.  To replace such approaches, a new way to predict the long-term ageing was proposed in this Thesis, utilizing the found influences of mixture morphology and fundamental mechanism. Though additional mechanisms and non-linear coupling between them may be still needed to reach the ‘ultimate’ ageing prediction model, the current model was found to be a significant improvement to the currently used methods and may lead the way towards further enhancing the fundamental knowledge towards asphalt mixture ageing (Paper V).

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2014. s. xi, 94
Serie
TRITA-TSC-PHD ; 14:002
Nyckelord
Ageing, Aggregate packing, Atomic force microscopy, Asphalt mixture, Bitumen, Diffusion, Finite element analysis, Gradation, Micro-structure, Mixture morphology, Oxidative ageing, Surface ageing
Nationell ämneskategori
Samhällsbyggnadsteknik
Identifikatorer
urn:nbn:se:kth:diva-145051 (URN)978-91-87353-37-6 (ISBN)
Disputation
2014-05-23, Q2, Osquldas väg 10, KTH, Stockholm, 09:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20140509

Tillgänglig från: 2014-05-09 Skapad: 2014-05-07 Senast uppdaterad: 2014-05-09Bibliografiskt granskad

Open Access i DiVA

Fulltext saknas i DiVA

Övriga länkar

Förlagets fulltextScopus

Personposter BETA

Birgisson, BjörnJelagin, DenisKringos, Niki

Sök vidare i DiVA

Av författaren/redaktören
Das, Prabir KumarBirgisson, BjörnJelagin, DenisKringos, Niki
Av organisationen
Väg- och banteknik
I samma tidskrift
Materials and Structures
Samhällsbyggnadsteknik

Sök vidare utanför DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 247 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf