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Investigating effects of salts on the coalescence process in bitumen emulsions
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.ORCID iD: 0000-0003-3968-6778
(English)In: Article in journal (Refereed) Submitted
Abstract [en]

The breaking and coalescence process in bitumen emulsions during their application strongly influences the resulting long-term mechanical performance of the cold mix asphalt. This phase separation process is affected by physico-chemical changes at the bitumen/water interface. This paper describes the effects of addition of different salts on the destabilization of bitumen emulsions. This study is limited mainly to cationic rapid setting (CRS) bitumen emulsions and salts which are very commonly added to these emulsions as a stabilizer. However, a few samples with non-ionic emulsifiers were also prepared and analyzed comparatively to understand the electrostatic force balance with varying concentrations of selected salts. The experimental part includes a bitumen droplet relaxation test, droplet size distribution measurement, microscopy, and evaluation of physico-chemical properties of prepared soap solutions e.g. interfacial tension and density measurements. Some experiments on the effect of selected water-soluble organic solvents on the coalescence process were also carried out. The results showed that coalescence was delayed after the addition of salts, while the water soluble organic solvents proved not to affect the emulsion significantly. 

Keywords [en]
Cold Mix Asphalt, Bitumen Emulsions, Breaking, Coalescence, Relaxation, Salts, Organic Solvents.
National Category
Engineering and Technology
Research subject
Civil and Architectural Engineering
Identifiers
URN: urn:nbn:se:kth:diva-223443OAI: oai:DiVA.org:kth-223443DiVA, id: diva2:1184455
Note

QC 20180221

Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-02-23Bibliographically approved
In thesis
1. Towards the enhanced applicability of cold mix asphalt:: An experimental study focusing on surface free energies and the breaking and coalescence of bitumen emulsions
Open this publication in new window or tab >>Towards the enhanced applicability of cold mix asphalt:: An experimental study focusing on surface free energies and the breaking and coalescence of bitumen emulsions
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The environmental, social and economic sustainability of our infrastructure network is clearly of paramount importance to the road-engineering sector as well to society at large. Sustainable road materials and reduced transport of those materials therefore play a significant role. Cold mix asphalt (CMA) emulsion technology could be one of the better options for the road industry to explore more thoroughly. Given its lower start-up and equipment installation costs, lower energy consumption and reduced environmental impact, CMA should offer a reliable alternative to some of the Hot Mix Asphalt (HMA) or Warm Mix Asphalt (WMA) options. As CMA is not a new technology, there are many reasons why this material is not currently being used as extensively as it might be. Though risk adverseness of the market may be partly to blame for this, a number of technical challenges and uncertainties related to material behavior are certainly responsible. This thesis has addressed some of the important technical challenges, aiming to provide more guidance in material selection and design, and prediction of the behavior of emulsion-based CMAs. To do so, this research has focused on aspects of the correct formulation of the bitumen emulsions, how to select the correct combinations of material components, and how to control the breaking and coalescence processes in bitumen emulsions better, resulting in usable and predictable adhesive and cohesive bond strengths. Though most of the laboratory and modeling choices that were made in this thesis are based on theoretical considerations, the main contribution is the test protocol development. The systematic surface free energy measurements of the material components, combined with the test set-up to monitor controllably the breaking and coalescence behavior of bitumen droplets in an emulsified environment, gives a new way to approach the design of CMA. It is recommended that future research is focused on taking the developed protocols as a basis for enhanced mix design and making a direct link to validated long-term mechanical properties on the asphalt mixture scale.

Abstract [sv]

Miljömässig, social och ekonomisk hållbarhet är av största betydelse för vår infrastruktur både inom vägbyggnadsområdet och inom samhället i stort. Där kan hållbara vägbyggnadsmaterial och minskade transporter av vägbyggnadsmaterial ge ett betydande bidrag. Tekniken med kallblandade asfaltemulsionsbeläggningar (CMA) är en av de bättre lösningarna för vägbyggnadsindustrin som skulle kunna användas i större utsträckning än som görs för närvarande. Givet teknikens låga uppstarts- och investeringskostnader, minskad energiförbrukning och minskad miljöpåverkan, kan CMA bli ett attraktivt alternativ till varmblandade (HMA) och halvvarma (WMA) asfaltmassor. Då CMA inte är någon ny teknik, finns många skäl att fundera över varför denna teknik inte praktiseras i så stor omfattning idag. Obenägenheten att ta risker med ny teknik på marknaden delvis kan beskyllas för detta, men också ett flertal osäkerheter kopplade till materialegenskaper hos CMA kan också bidra. Denna avhandling har studerat några viktiga tekniska utmaningar med syfte att ge mer vägledning vid materialval och utformning, samt att förutse materialbeteenden hos emulsionsbaserade CMA. För att nå detta har denna forskning fokuserats på sammansättningen av bitumenemulsioner, hur man väljer rätt kombination av materialkomponenter och hur man får en bättre kontroll på brytförloppet och koalescensen, med målet att kunna förutsäga adhesiv och kohesiv bindningsstyrka. Då de flesta laborativa och modelleringsmässiga valen i denna avhandling är baserade på teoretiska överväganden, är det viktigaste bidraget i denna rapport utvecklingen av testprotokollen. De systematiska mätningarna av fri ytenergi hos materialkomponenterna, kombinerat med testmetoder för att på ett kontrollerat sätt studera bryt- och koalescensbeteendet hos droppar i en emulsionsmiljö, ger en ny möjlighet att optimera sammansättningen av CMA. Det rekommenderas att framtida forskning fokuseras på att ta de föreslagna protokollen som bas för förbättrad proportionering och att göra en direkt koppling till validerade mekaniska långtidseffekter på asfaltbeläggningen.

 

 

Nyckelord

 

Bitumen, Kallblandad Asfalt, Mineraler/Aggregat, Fri Ytenergi, Sorption, Kontaktvinkel, Bitumenemulsioner, Brytning och Koalescensen, Emulgatorer, Adhesionsegenskaper.

Place, publisher, year, edition, pages
Stockholm, Sweden: KTH Royal Institute of Technology, 2018. p. 58
Series
TRITA-ABE-DLT ; 1802004
Keywords
Bitumen, Cold Asphalt Mixtures, Minerals/Aggregates, Surface Free Energy, Sorption, Contact Angle, Bitumen Emulsions, Breaking and Coalescence, Emulsifiers, Adhesion Promoters., Bitumen, kallblandad asfalt, mineraler/aggregat, fri ytenergi, sorption, kontaktvinkel, Bitumenemulsioner, brytning och koalescensen, emulgatorer, adhesionsegenskaper
National Category
Engineering and Technology
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-223445 (URN)978-91-7729-699-7 (ISBN)
Public defence
2018-03-16, Kollegiesalen, Brinellvägen 8, KTH Royal Institute of Technology, Stockholm, Sweden, 10:00 (English)
Opponent
Supervisors
Note

QC 20180221

Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-03-06Bibliographically approved

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