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Towards frost damage prediction in asphaltic pavements
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.ORCID iD: 0000-0001-8718-1411
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Roads are subjected to mechanical loads from the traffic as well as deteriorating mechanisms originating from the surrounding environment and climate. The damage arising is particularly severe during the winter season, when for example raveling, pot holes and cracks can emerge on the surfaces of asphaltic roads. These winter related damages are difficult to characterize and predict, partly due to the complexity of the asphalt material and partly since they cannot be linked to one single phenomenon but several, such as the (long term) existence of moisture, frost damage and frost heave, low temperature cracking and the embrittlement of the mastic at low temperatures. Further adding to the complexity is the combination of these phenomena which may accelerate the emergence and evolution of the damage mechanisms. This licentiate research project is mainly focusing on the emergence and development of frost damage in the asphalt layer but will include the effect of other damage mechanisms in its continuation. The goal of the project is to develop a multiscale model able to predict the damage development in an asphalt pavement during a desired period of time, to enhance maintenance predictions as well as pavement design choices. This licentiate thesis is the first part of this project and aims to lay the foundation of the multiscale model. To achieve this, a micromechanical model of frost damage in asphalt mixtures has been developed. This model couples the moisture and mechanical damage happening on the short and long term, caused by the infiltration of moisture and the expansion of water turning into ice during temperature drops. Both possible adhesive damage in the mastic-aggregate interface and cohesive damage in the mastic is included. In addition to the developed micromechanical model, this thesis presents the overall concept for the formulation of the multiscale model as well as discusses about its motivations and advantages.

Abstract [sv]

Vägar utsätts både för mekaniska laster från trafiken som kör på vägen samt för nedbrytande mekanismer härstammande från den omgivande miljön och klimatet. Skadorna som uppstår är särskilt stora under vintern, då till exempel stensläpp, potthål och sprickor kan uppstå på ytan av asfalterade vägar. Dessa vinterrelaterade skador är svåra att karakterisera och förutsäga, delvis på grund av det komplexa beteendet hos asfalt och delvis eftersom de inte härstammar från enbart ett fenomen utan flera, såsom existensen av fukt i asfalten (på lång sikt), frostskador, tjällyft, sprickbildning på grund av låg temperatur samt försprödningen av asfalt som sker vid låga temperaturer. Vidare påverkar dessa skademekanismer varandra vilket kan accelerera skadebildningen och utvecklingen, vilket ytterligare ökar komplexiteten. Detta licentiatforskningsprojekt fokuserar till största delen på uppkomsten och utvecklingen av frostskador men kommer även inkludera effekten av andra skademekanismer i dess fortsättning. Målet med detta forskningsprojekt är att utveckla en multiskalemodell som kan förutspå skadeutvecklingen i en asfaltsväg under en önskad tidsperiod, för att förbättra både underhållsprognoser samt designval. Denna licentiatuppsats är den första delen i detta projekt och syftar till att lägga grunden till multiskalemodellen. För att uppnå detta har en mikromekanisk modell av frostskador i asfalt utvecklats. Denna modell kopplar ihop fuktskadan och den mekaniska skadan som sker både på kort och lång sikt, orsakad av infiltrationen av fukt och expansionen av vatten som omvandlas till is vid sjunkande temperatur. Modellen inkluderar de möjliga skadorna som uppstår i både mastics och gränsskiktet mellan mastics och stenmaterialet. Utöver den utvecklade mikromekaniska modellen presenterar denna uppsats det övergripande konceptet för formuleringen av multiskalemodellen samt diskuterar dess motivering och fördelar.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019.
Series
TRITA-ABE-DLT ; 1917
Keywords [en]
frost damage, winter damage, asphalt, pavements, micromechanical model, microstructure, freeze-thaw cycles, finite element model
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
URN: urn:nbn:se:kth:diva-251389ISBN: 978-91-7873-222-7 (print)OAI: oai:DiVA.org:kth-251389DiVA, id: diva2:1315843
Presentation
2019-06-12, V3, Teknikringen 72, Stockholm, 10:30 (English)
Opponent
Supervisors
Note

QC20190515

Available from: 2019-05-15 Created: 2019-05-15 Last updated: 2019-05-15Bibliographically approved
List of papers
1. Freeze-thaw damage in asphalt: a set of simplified simulations
Open this publication in new window or tab >>Freeze-thaw damage in asphalt: a set of simplified simulations
2018 (English)In: Proceedings of Canadian Technical Asphalt Association 63rd Annual Conference / [ed] Stephen Goodman, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Winter damage in pavements, such as potholes, dislodging of stones and structural layer separation, occurs during and after winter seasons. This damage is caused by several processes, such as freezing and thawing action, moisture accumulation, traffic loads and winter maintenance actions, which combined makes winter damage a highly complex phenomenon. To better understand this process and, in the future, being able to predict the damage propagation by modeling, this paper discusses the possibility to separate these actions and phenomena into different cases. The focus in this paper is on the freezing -and thawing damage and how it is affected by different environmental conditions, inspired by real weather data from the City of Luleå in the north of Sweden. To investigate this, a microscale model is utilized. The results from the simulations show an increasing adhesive damage with the number of freeze-thaw cycles while the cohesive damage in the viscoelastic mastic increases is the most severe for a period with several days of freezing temperatures. A discussion of how the separation of winter damage into different cases will contribute to the ultimate goal of a multiscale model is also included.

Keywords
Asphalt, Micromechanics, FEM
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-247712 (URN)
Conference
Canadian Technical Asphalt Association 63rd Annual Conference
Note

QC 20190513

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-05-15Bibliographically approved
2. Modeling the evolution of winter damage in an asphalt concrete microstructure
Open this publication in new window or tab >>Modeling the evolution of winter damage in an asphalt concrete microstructure
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Winter damage in asphalt pavements is a complex phenomenon which may cause pothole formation, dislodging of stones and structural layer separation. In order to reduce the winter damage, knowledge about the process in both the pavement and on a microstructural level is required. This paper focuses on modeling the process of damage evolution on a microstructural level in order to identify and understand the different phenomena influencing the degradation process. In this paper the evolution of winter damage in an asphalt concrete microstructure was modeled throughout the course of two winter seasons. The simulations include freezing and thawing cycles as well as additional damage originating from snow plows, both based on real weather data from Luleå in the north of Sweden. The results show a large increase of damage in both the mastic and the aggregate-mastic interface, and thereby also vertical displacement of the top surface, after the first freeze-thaw cycle. During the following freeze-thaw cycles the mastic damage continuous to increase but with a decreasing rate while the damage in the aggregate-mastic interface is only affected by the manually added damage from the snow plow. These results indicate a need to include the growth of -and emergence of new air voids in the model as well as an investigation of the actual behavior and influence of the damage evolution in the interface regions.

Keywords
Asphalt, pavement engineering, damage, FEM, Micromechanics
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-247715 (URN)
Conference
The Transportation Research Board (TRB) 98th Annual Meeting, Washington DC, January 13–17, 2019
Note

QC 20190513

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-05-15Bibliographically approved
3. A micromechanical model of freeze-thaw damage in asphalt mixtures
Open this publication in new window or tab >>A micromechanical model of freeze-thaw damage in asphalt mixtures
(English)In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268XArticle in journal (Refereed) Submitted
Abstract [en]

Freeze-thaw damage in asphalt pavements is a complex phenomenon depending on many parameters such as moisture infiltration, temperature and mechanical properties of the asphalt constituents as well as the interface between them. As a first step in creating a comprehensive multiscale model including all of these parameters, a micromechanical model has been developed. This model couples the infiltration of moisture and the associated damage, the expansion caused by the water inside the air voids freezing, and the mechanical damage. The expansion of the air voids is implemented by applying a volumetric expansion in the air voids dependent on the temperature. The cohesive damage in the mastic and adhesive damage in the mastic-aggregate interface are included by implementing an energy based damage model and the cohesive zone model, respectively. To show the capabilities of the model, two different graded microstructures were exposed to 10 freeze-thaw cycles each and their stiffness was evaluated before and after the simulated freeze-thaw cycles. In addition, the sensitivity of the resulting damage to the time the microstructure was exposed to temperatures below zero was evaluated by simulating freeze-thaw cycles with a total time ranging between 10 hours and 14 days. From the analyses it was concluded that the model was capable of capturing the deteriorating effect of an increasing number of freeze-thaw cycles, and was sensitive to the freezing time in the freeze-thaw cycles.    

Keywords
Frost damage; Moisture damage; Modelling; Asphalt mixture; Microstructure; FEM
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-251375 (URN)
Note

QCR 20190514

Available from: 2019-05-13 Created: 2019-05-13 Last updated: 2019-05-15Bibliographically approved

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