På 60-talet genomfördes det försök, både i Sverige och i USA, med olika typer av gummiasfalt. I Sverige utvecklads den torra processen som bygger på att blanda gummifraktioner, tillverkade från gamla däck, samt stenmaterial innan bitumen blandas in för att skapa en asfaltsmassa. I USA utvecklades den våta processen som bygger på att blanda gummifraktioner och bitumen innan detta tillsätts till stenmaterialet för att skapa en asfaltsmassa. Under 2000-talet har Trafikverket startat projekt med gummiasfalt gjord genom den våta processen. Mindre fält- och laboratoriestudie med GMB i bland annat det bundna bärlagret har genomförts vid en industrianläggning. I detta arbete har en omfattande litteraturstudie gjorts inom ämnet med fokus på beläggningar med gummimodifierat bitumen. Utländska erfarenheter och kunskaper har studerats. Svenska tester i fält och i laboratorier har studerats närmare och har utvärderats genom modellering. En gummimodifierad asfalt (GAP 16) har jämförts med en referensbeläggning ABS 16. Spårdjup på grund av permanent deformation och livslängd genom utmattning har blivit modellerad baserat på tidigare resultat från laboratoriestudier och fältstudier. Modelleringen av spårdjup i slitlager på grund av permanent deformation har genomförts med visko-elastisk analys. Modelleringen har tagit hänsyn till ett antal olika klimat, trafikbelastningar och hastigheter som är typiska för svenska förhållanden. För att definiera nödvändiga reologiska egenskaper har masterkurvor blivit skapade av laboratorieresultat. En linjärelastisk analys har blivit utförd för att undersöka livslängd baserad på utmattning då olika beläggningskombinationer används i konstruktioner. Samt undersöks fördelningen av olika lagertjocklekar för slitlager, bindlager och bundet bärlager. Resultatet från den visko-elastiska analysen visade att en beläggning med gummimodifierat bitumen har mindre permanent deformation jämfört med en vanlig svensk slitlagerbeläggning. Detta gällde vid samtliga undersökta ställen i Sverige. Den linjärelastiska analysens resultat påvisade tekniska mervärden vid användning av gummimodifierat bitumen i bundet bärlager jämfört med konventionell svenskt bundet bärlager. Det tekniska mervärdet var att längre livslängd av konstruktionen med avseende på utmattning. Dessutom kan den totala beläggningskonstruktionens tjocklek minskas vid användning av gummimodifierat bitumen i det bundna bärlagret. Skillnaden mellan beläggningarna i den visko-elastiska analysen var temperaturberoende. Det innebär att ju varmare klimat, desto bättre presterar det undersökta slitlagret med GMB jämfört med den vanliga undersökta slitlagerbeläggningen ABS 16. Resultaten visade att om GMB användes i något av de övre lagren, slitlager och/eller bindlager, ökar töjningar i underkant bundet bärlager i teorin. Det innebär att det bundna bärlagret klarar färre antal belastningar innan sprickbildning uppstår i underkant, dvs att livslängden på konstruktionen minskar. / Various types of rubberized asphalt was tested and evaluated in the 1960s in both Sweden and the United States. In Sweden, the dry process was developed. It is based on mixing tire rubber granulates, with the aggregates before the addition of bitumen in the asphalt mixing process. In the USA, the wet process was developed. It is based on mixing tire rubber granulates and bitumen before adding it to the aggregates in the asphalt mix. The last decade the Swedish Transport Administration has evaluated pavements based on the wet process in laboratory and field tests. In addition, a minor field and laboratory study on the performance of rubbermodified bitumen used in bound base mix was conducted on an industrial site. In this work, a comprehensive literature review focusing on rubbermodified pavement mix performance has been compiled. Foreign experience and knowledge have been studied along Swedish laboratory tests and field studies. The results has been used for modeling of rubbermodified pavement mix performance. A rubbermodified asphalt mix (GAP 16) has been benchmarked with a typical Swedish reference asphalt mix (ABS 16). Plastic rutting and fatigue life time has been modelled based on laboratory tests and field study results from Swedish projects. Modelling of permanent deformations (rutting) has been conducted based on viscoelastic analysis for different climate scenarios, traffic load and velocities typical for Swedish conditions. Master curves to define the rheological properties has been constructed from laboratory data. A linear elastic analysis was conducted to analyze the fatigue lifetime of different pavement layouts, i.e. distribution of thickness between wearing course, binder course and bound base. The results of the viscoelastic analysis showed that the rubber modified bitumen mix has less permanent deformation compared with the standard wearing course mix. This applies to all studied climate conditions in Sweden. It was also found that bound base course with rubbermodified bitumen has added technical value compared to a conventional base course by a higher resistance towards fatigue failure. There is a possibility to reduce the total thickness of the pavement when using the rubber modified bitumen in the bound base layer. The results showed that the difference between the asphalts mixes in the viscoelastic analysis was temperature dependent. The performance of rubbermodified mix is better in warmer climate conditions compared to colder. Since rubber modified bitumen has lower stiffness modulus the use in in any of the upper layers, wearing course and / or binder course, increases the strain in the lower edge of the bound base course. It reduces the fatigue life time of the pavement. If rubbermodified bitumen is used in the bound base layer it increases the life time since it has higher resistance towards fatigue failure.

No description available.

A series of laboratory accelerated immersion tests are used to examine the effects of different chemicals found in municipal solid waste leachate, geomembrane thickness, and incubation temperatures on the degradation of different high density polyethylene geomembranes. It was found that surfactant was the key leachate constituent affecting antioxidant depletion while salts accelerated degradation of the mechanical properties, especially stress crack resistance. Immersed in synthetic leachate, the time to nominal failure at 35oC was predicted to be 62% longer for the 2.5 mm, and 12% longer for the 2.0 mm, than for the 1.5 mm geomembrane tested. The antioxidant depletion in synthetic leachate and air at temperatures > 85oC was consistent with what would be expected from Arrhenius modeling based on data from lower temperatures (≤ 85oC). However, the early depletion rates in water incubation decreased with the increase of the temperature above 100oC. It was also found that at temperatures above 100oC, there was significant change in the polymer morphology that affected the stress crack resistance at early incubation times prior to polymer degradation. Large-scale geosynthetic liner longevity simulators (GLLSs) which simulated field conditions were used to investigate the susceptibility of pre-aged high density polyethylene geomembranes to stress cracking and to evaluate the performance of geomembranes under a 150 mm sand protection layer. A pre-aged geomembrane with a 560 g/m2 geotextile protection layer experienced brittle rupture at local gravel indentations. The time to failure was correlated to the incubation temperatures. The use of a sand protection layer not only delayed antioxidant depletion compared to that with a traditional geotextile protection but also substantially reduced the long-term tensile strains in the geomembrane below the allowable strain limits. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-11-26 12:36:01.538