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Bitumen Based Intrinsically Icephobic Road Surfaces

English title Bitumen Based Intrinsically Icephobic Road Surfaces
Applicant Poulikakos Lily
Number 169122
Funding scheme Project funding (Div. I-III)
Research institution Eidg. Materialprüfungs- und Forschungsanstalt (EMPA)
Institution of higher education Swiss Federal Laboratories for Materials Science and Technology - EMPA
Main discipline Civil Engineering
Start/End 01.05.2017 - 30.04.2020
Approved amount 191'508.00
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Keywords (4)

Icephobicity; Mechanical tests; Road surfaces; Safety

Lay Summary (German)

Lead
Getragen vom gestiegenen Verständnis im Bereich der wasserabweisenden Materialien und den zunehmenden technologischen Möglichkeiten ihrer Herstellung und ihres Einsatzes in gesellschaftlich und industriell relevantem Kontext, hat sich die Schaffung einer wissenschaftlichen Grundlage und die Erforschung von intrinsisch eisabweisenden Strassenbelägen (ohne Verwendung von Frostschutzmittel) zur nächsten Herausforderung entwickelt. Dieses Forschungsprojekt soll das grundlegende Wissen zur Bildung und Anhaftung von Eis an Strassenbelägen ausbauen. Das Thema hält erhebliche Herausforderungen, jedoch gleichzeitig auch offensichtlichen Nutzen bereit.
Lay summary
 

Vereiste Strassen sind eine ernstzunehmende Gefährdung. Der Winterdienst in der Schweiz umfasst sowohl die Schneeräumung, als auch die Strassenenteisung. Die damit verbundenen, wiederkehrenden Kosten belaufen sich auf ca. 20 bis 50 Millionen CHF pro Jahr. Dies stellt 15 bis 25% der gesamten, jährlichen Strasseninstandhaltungskosten dar. Die Entwicklung von Strassenbelägen, die Vereisung verzögern oder verhindern, sowie die Anhaftung von Eis verringern, hat soziale, wirtschaftliche und ökologische Vorteile, da die Strassensicherheit erhöht, die Unterhaltskosten reduziert und die Verwendung von Enteisungsmitteln vermieden werden können. Das übergeordnete Ziel dieses Projektes ist es, die physikalischen Grundlagen der Bildung und Anhaftung von Eis auf Strassenoberflächen zu verstehen. Dies geschieht im Kontext der hohen Anforderungen an Strassenbeläge in Bezug auf Sicherheit, Langlebigkeit und Umweltverträglichkeit. Die entwickelten Materialien werden über ihre eisabweisenden Eigenschaften hinaus, auf ihre Konformität mit den Anforderungen für Strassenbeläge geprüft. Das geplante Projekt vereint das breite Fachwissen der Abteilung Strassenbau / Abdichtungen der EMPA im Bereich bituminöser Strassenmaterialien mit dem grundlegenden Wissen des Labors für Thermodynamik in neuen Technologien an der ETH Zürich im Bereich Oberflächen-Eis-Physik. Im Rahmen des Projektes werden eisabweisende, bituminöse Baustoffe entwickelt und ihre Eigenschaften in den Bereichen des mechanischen Versagens, der Sicherheit und der Umweltverträglichkeit geprüft. Dadurch wird sichergestellt, dass die Hauptanforderungen an einen Strassenbelag weiter gewährleistet werden.

Direct link to Lay Summary Last update: 19.04.2017

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Associated projects

Number Title Start Funding scheme
140210 A Multi-Scale Investigation of Recycled Asphalt Concrete 01.09.2012 Project funding (Div. I-III)
157122 High Performance Aggregates for Sustainable Road Pavements 01.04.2015 Project funding (Div. I-III)
152980 RECYCLING ASPHALT CONCRETE EXPLORING FUNDAMENTAL ASPECTS OF THE INTERFACES 01.09.2014 Project funding (Div. I-III)
157086 Modification of Asphalt Concrete using Nanofibrillated Cellulose 01.02.2015 Project funding (Div. I-III)
143651 Wetting and drying of porous asphalt pavement: a multiscale approach 01.02.2013 Project funding (Div. I-III)

Abstract

Driven by recently improved understanding of superhydrophobicity and the increasing availability of technologies to realize it for surfaces with direct societal and industrial relevance, the next emerging frontier is to develop a science base for icephobic road surfaces, going beyond traditional periodic application of chemical treatments. The aim of this proposal is to advance our fundamental knowledge of ice formation and ice adhesion on road surfaces, a topic which carries with it significant challenges but also obvious significant benefits.Icy roads are an important hazard and winter maintenance in Switzerland includes the removal of snow as well as anti-icing measures. There are considerable recurring costs associated to this maintenance, ca. 20 to 50MCHF, adding up to 15-25% of the yearly road maintenance budget. Developing road surfaces that resist and/or retard the formation of ice and/or reduce ice adhesion has social, economic and environmental benefits as it can improve safety, reduce maintenance costs and reduce the use of anti-icing chemicals that affect the environment. The overall goal of this project is to understand the physics of ice formation and ice adhesion on road surfaces, which come with stringent requirements stemming from their required functionality with respect to safety, longevity and environmental compatibility as well as to point to directions on how such knowledge could be employed to develop road surfaces in the future that, in addition, offer intrinsically (based on their structure and composition) highly resistive properties to ice formation and/or adhesion. Current state of knowledge indicates that surface texture topography and its design can play an important role in producing such surfaces. Such topographies for asphalt surfaces will be investigated during the proposed project. Furthermore, the mechanical compliance (deformability) of the road surface and its role in retardation of ice formation and adhesion will be studied. The third important parameter targeted by the proposed project is road material chemical composition with respect to ice formation retardation, a key aspect that will be studied simultaneously with the two structural properties mentioned above. The study will cover a broad range of sub-zero temperatures, corresponding to typical winter and cold region environments conducive to icy roads. Finally all developed materials will be tested for compliance with standard requirements for road materials. The proposed project brings together the broad know-how on bituminous road materials and their re-quirements from the Empa laboratory for road engineering/sealing components complemented by the fundamental know-how in the general area of surface ice physics and engineering from the laboratory for thermodynamics in emerging technologies at ETH Zurich. The project will develop icephobic bitu-minous materials and also investigate their adherence with standard road material requirements re-garding mechanical failure, safety and environmentally benign performance, to assure that the main functionality in terms of mechanical and safety requirements are not compromised. In order to understand and develop the necessary solutions for a rational method to develop ice-phobic road surfaces a multi-scale approach is necessary and will be realized as listed below. Parts A, B and C comprise the novel developments in this project and Parts D and E focus on the necessary functionality requirements. Part A Investigation of the role of surface texture (hierarchical micro- and nanoscale) and surface complianceThe effect of wetting in terms of contact angles of water and ice with the surface will be investigated using various relevant surface textures with the goal of developing surfaces that help retard the ice nucleation and adhesion. Of particular interest is the freezing delay time as a function of hierarchical roughness (roughness at various scales) values for minimal water or ice contact (mm to micron as well as sub-micron length scales are relevant in this respect) and the effect of such textures on the freezing temperature. In this context, the effect of surface compliance or deformability, on ice adhesion is expected to be an important aspect, which will be investigated using nano-indentation techniques. Furthermore, the effect of anti-icing additives (see also Part B) that are able to survive attrition or abrasion over time under road service environment, to enhance the anti-icing properties will be studied. The use of specially engineered fibers in terms of micro- and nanostructure and combined hierarchical topography with the required strength that would be compatible for asphalt and deliver the desired surface texture are important options for the targeted material composition and will be explored. Part B Investigation of the role of “built-in” surface chemistry (nano- and subnanoscale) and (nano to micro-scale)The effects of surface chemistry of both the binder and the mineral aggregates will be studied. It is important to consider both these component of the surfaces as well as their combination, typically found in the road material composite, as they both come in contact with water and ice and they have very different physical and chemical properties. Specifically, we will study the wettability with respect to water, determine ice and water contact angles and observe how the consequent freezing behavior and ice adhesion are affected.Part C Anti-icing property characterization (micro and meso-scale mm)Ice adhesion strength and the corresponding force characterization as related to ice-surface contact area, which will be measured at the micro scale using a force sensor method already successfully em-ployed in the lab of the ETH national collaborator (LTNT). At the meso-scale shear tests will be per-formed in a conditioning chamber in order to determine the shear strength needed to separate ice blocks from compacted asphalt mixtures with the designed surface textures. To this end, using the modified Layer-Parallel Direct Shear Test (LPDS), ice adhesion performance will be determined. Part D: Investigation of the mechanical properties in the laboratory scale (meso-scale-mm) The laboratory-produced mixtures have to perform as required by the road material standards. Here it will be shown that the materials and surfaces developed in this work do not compromise performance with respect to durability and safety.Part E: Environmental assessment. The environmental effect of the developed mixtures will be de-termined with respect to leaching of compounds for example polycyclic aromatic hydrocarbons (PAHs), run-off water chemical characteristics and UV sensitivity.
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