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| 2. |
- Andersson, Louise
(author)
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Continuous Preventive Bridge Maintenance : Effect of High Pressure Washing on Concrete Bridges
- 2022
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Licentiate thesis (other academic/artistic)abstract
- In Sweden, as in many other countries, preventive maintenance of structures andbridges is considered important. It provides several benefits such as prolonged lifespan or service life, less need for repair, and hopefully reduced costs and lowerenvironmental impact.A large part of Sweden’s bridge stock is getting quite old. The idea that small actionscan improve and/or prolong the status of the bridge and postpone needs for repairor prevent damage with a reduction in life cycle cost is generally in the owner’sinterest. One such preventive maintenance measure is the annual washing ofbridges. While clear positive effects have been observed on the expansion joints,drainage system, and the bridge’s visual appearance, an important question is howthe washing affects chloride ingress, mainly from de-icing salts, in reinforcedconcrete bridge members. The hypothesis is that the high-pressure washing cleansaway the contaminants on the surface and in the long run reduces the chloridecontent. While the practical experience has been positive in Sweden, no research hasyet been done concerning the effect of high-pressure washing on chloride ingress inconcrete bridges.A study has been conducted on the preventive bridge maintenance practice of theSwedish Transport Administration (STA) and Swedish municipalities. This work hasbeen based on a literature review, a survey of municipalities’ bridge maintenance,and practical participation with contractors during annual maintenance. Field andlaboratory tests were carried out on the effect of washing on chloride ingress in twotypes of concrete. A field station was installed on an edge beam of a bridge and wasfollowed over three years’ exposure including winter seasons, winter maintenance,and annual washing in June. Also, an accelerated test method was developed in thelaboratory to simulate the yearly exposure and test the effect of high- pressurewashing in a long-term simulation over just a few weeks.The practical aspects of bridge maintenance seem to be quite similar betweenSweden and in other countries. However, in terms of descriptions of and availablemeans for maintenance and repairs, there seem to be larger differences. For the fieldstation, the results after one year’s exposure do not show anything more than theanticipated difference in chloride ingress between the two concrete types understudy. For year two, a slight difference indicated that washed samples had a reducedchloride content. For year three, however, there was no distinct difference betweenivwashed and unwashed samples. The reasons for this need to be further investigatedand examined. This will be done in the continuous tests of field exposure.The laboratory test method has been developed and successively improved. The shape and levels of chloride ingress are reasonable and comparable with fieldsamples. However, there is a need to examine the effect of natural rain exposurewhich might have the same or greater effect of diluting the chloride content aswashing the surface once a year. Other factors also need to be considered, such aswhen and how often the maintenance is performed. A first step to be able to examinethis has been completed through the development of the accelerated test method.
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| 3. |
- Butt, Ali Azhar, et al.
(author)
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Environmental friendly wax modified mastic asphalt
- 2009
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Conference paper (peer-reviewed)abstract
- Mastic asphalt products (Gussasphalt) require high working temperatures, and harder requirements concerning bitumen fumes and carbon dioxide emissions. Consequently, the need of a new means of producing and placing mastic asphalt at lower temperatures is particularly large. One way of reducing asphalt mixture temperature is by using special flow improving additives like wax. This technique has successively been tried for polymer modified mastic asphalt used for bridge decks and parking areas in Sweden. However, there still are uncertainties about possible negative impact on crack susceptibility at lower temperatures due to wax additives.In this study, 4% montan wax (Asphaltan A) was used for one particular polymer modified mastic asphalt product. Type and amount of wax additive was selected based on results from earlier studies. The impact on binder, binder/filler mixtures and mastic asphalt from production was tested in the laboratory, focusing on low temperature performance. The bending beam rheometer (BBR) was used for determining low temperature creep compliance and the tensile stress restrained specimen test (TSRST) for determining fracture temperatures. Binder properties were determined using dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) spectroscopy and conventional tests (softening point, penetration, elastic recovery, breaking point, viscosity and storage stability). Aging was performed using the rolling thin film oven test (RTFOT) at 200°C.As expected, the addition of wax to the polymer modified binder showed a viscosity reduction at higher temperatures, corresponding to a similar positive effect of more than 10°C on production and laying temperature for the mastic asphalt. DMA and BBR results showed some increase in stiffness and a more elastic response of the wax modified binder at medium and low temperatures. The TSRST fracture temperature was 5 °C higher for the mastic asphalt containing wax, indicating however no dramatic negative impact on crack susceptibility.
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| 5. |
- Dar, Pe'er, et al.
(author)
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Cell-free DNA screening for prenatal detection of 22q11.2 deletion syndrome.
- 2022
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In: American journal of obstetrics and gynecology. - : Elsevier BV. - 1097-6868 .- 0002-9378. ; 227:1
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Journal article (peer-reviewed)abstract
- Prenatal screening has historically focused primarily on detection of fetal aneuploidies. Cell-free DNA (cfDNA) now enables noninvasive screening for subchromosomal copy number variants, including 22q11.2 deletion syndrome (22q11.2DS or DiGeorge syndrome), which is the most common microdeletion and a leading cause of congenital heart defects and neurodevelopmental delay. Although smaller studies have demonstrated the feasibility of screening for 22q11.2DS, large cohort studies with postnatal confirmatory testing to assess test performance have not been reported.To assess the performance of SNP-based cfDNA prenatal screening for detection of 22q11.2DS.Patients who had SNP-based cfDNA prenatal screening for 22q11.2DS were prospectively enrolled at 21 centers in 6 countries. Prenatal or newborn DNA samples were requested in all cases for genetic confirmation with chromosomal microarray. The primary outcome was sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of cfDNA for detection of all deletions, including the classical deletion and nested deletions that are ≥500kb, in the 22q11.2 low copy repeat A-D region. Secondary outcomes included the prevalence of 22q11.2DS and performance of an updated cfDNA algorithm that was evaluated blinded to pregnancy outcome.Of 20,887 women enrolled, genetic outcome was available in 18,289 (87.6%). Twelve 22q11.2DS cases were confirmed in the cohort, including five (41.7%) nested deletions, yielding a prevalence of 1:1524. In the total cohort, cfDNA reported 17,976 (98.3%) as low risk for 22q11.2DS and 38 (0.2%) as high-risk; 275 (1.5%) were non-reportable. Overall, 9 of 12 cases of 22q11.2 were detected, yielding a sensitivity of 75.0% (95% CI: 42.8, 94.5); specificity of 99.84% (95% CI: 99.77, 99.89); PPV of 23.7% (95% CI: 11.44, 40.24) and NPV of 99.98% (95% CI: 99.95, 100). None of the cases with a non-reportable result was diagnosed with 22q11.2DS. The updated algorithm detected 10/12 cases (83.3%; 95% CI: 51.6-97.9) with a lower false positive rate (0.05% vs. 0.16%, p<0.001) and a PPV of 52.6% (10/19; 95% CI 28.9-75.6).Noninvasive cfDNA prenatal screening for 22q11.2DS can detect most affected cases, including smaller nested deletions, with a low false positive rate.
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| 6. |
- Dar, Pe'er, et al.
(author)
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Cell-free DNA screening for trisomies 21, 18 and 13 in pregnancies at low and high risk for aneuploidy with genetic confirmation
- 2022
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In: American journal of obstetrics and gynecology. - : Elsevier BV. - 1097-6868 .- 0002-9378. ; 227:2
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Journal article (peer-reviewed)abstract
- Cell-free DNA (cfDNA) non-invasive prenatal screening for trisomy (T) 21, 18, and 13 has been rapidly adopted into clinical practice. However, prior studies are limited by lack of follow up genetic testing to confirm outcomes and accurately assess test performance, particularly in women at low-risk for aneuploidy.To compare the performance of cfDNA screening for T21, T18 and T13 between women at low and high-risk for aneuploidy in a large, prospective cohort with genetic confirmation of results.A multicenter prospective observational study at 21 centers in 6 countries. Women who had SNP-based cfDNA screening for T21, T18 and T13 were enrolled. Genetic confirmation was obtained from prenatal or newborn DNA samples. Test performance and test failure (no-call) rates were assessed for the cohort and women with low and high prior risk for aneuploidy were compared. An updated cfDNA algorithm, blinded to pregnancy outcome, was also assessed.20,194 were enrolled at median gestational age of 12.6 weeks (IQR:11.6, 13.9). Genetic outcomes were confirmed in 17,851 (88.4%): 13,043 (73.1%) low-risk and 4,808 (26.9%) high-risk for aneuploidy. Overall, 133 trisomies were diagnosed (100 T21; 18 T18; 15 T13). cfDNA screen positive rate was lower in low- vs. high-risk (0.27% vs. 2.2%, p<0.0001). Sensitivity and specificity were similar between groups. The positive predictive value (PPV) for the low and high-risk groups was 85.7% vs. 97.5%, p=0.058 for T21; 50.0% vs. 81.3%, p=0.283 for T18; and 62.5% vs. 83.3, p=0.58 for T13, respectively. Overall, 602 (3.4%) patients had no-call result after the first draw and 287 (1.61%) after including cases with a second draw. Trisomy rate was higher in the 287 with no-call results than patients with a result on a first draw (2.8% vs. 0.7%, p=0.001). The updated algorithm showed similar sensitivity and specificity to the study algorhitm with a lower no-call rate.In women at low-risk for aneuploidy, SNP-based cfDNA has high sensitivity and specificity, PPV of 85.7% for T21 and 74.3% for the three common trisomies. Patients who receive a no-call result are at increased risk of aneuploidy and require additional investigation.
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| 7. |
- Edwards, Ylva, et al.
(author)
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Beläggningssystem på betong i parkeringshus och garage : en översikt
- 2012
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Reports (peer-reviewed)abstract
- Skador i form av rostande armering i olika typer av parkeringshus och garage uppstår enligt CBIs erfarenheter huvudsakligen i bjälklag, ramper och i de nedre delarna av väggar och pe-lare. Men denna typ av skador kan undvikas med rätt betongkvalitet, tillräckligt tjocka täck-skikt över armeringen och väl fungerande tätskiktsbeläggning. _x000D_ _x000D_ Det finns olika typer av beläggningar för parkeringshus. Mest vanligt är polymermodifierad gjutasfalt (PGJA) på tätskiktsmatta, men även betongpågjutningar förekommer. Sedan 2000-talets början har det blivit allt vanligare med olika typer av härdplastbaserade beläggningar. En anledning till detta är att beläggningen kan utformas i valfri färgsättning vilket ger stora estetiska möjligheter. Det är emellertid viktigt att valet av en sådan förhållandevis tunn be-läggning inte görs utan att krav samtidigt ställs på beläggningens egenskaper. Slitage, sprick-bildning och vidhäftningsförluster utgör de största problemen och utmaningarna för parker-ingsdäck. Beträffande beläggningens slitstyrka utsätts denna för dubbdäcksslitage i svenska parkeringshus, vilket inte är fallet i de flesta andra länder. Detta måste beaktas vid val av be-läggning och inte minst provningsmetod för bestämning av nötningsresistens hos belägg¬ningen i fråga. Beständighet mot klorider och andra på ett parkeringsdäck förekommande kemikalier är en annan viktig egenskap som måste redovisas._x000D_ _x000D_ I denna rapport beskrivs bland annat några av de olika typer av härdplastbaserade belägg-ningssystem som marknadsförs till parkeringshus och garage i Sverige, samt ges viss grund-läggande information om uppbyggnad, egenskaper och krav som kan ställas på systemen. Bitumenbaserade system, i huvudsak med tätskiktsmatta och gjutasfalt, behandlas också, lik-som specifikationer. Exempel på beläggningar på marknaden listas och en bilaga med refe-rensobjekt och exempel på förekommande skador avslutar rapporten._x000D_ _x000D_ I slutsatserna konstateras bland annat att:_x000D_ • En relevant och för parkeringsdäck anpassad kravspecifikation bör tas fram för att under-lätta för såväl beställare som tillverkare och entreprenörer. Bestämning av slitstyrka är centralt._x000D_ • Det finns behov av ytterligare forskningsinsatser inom området beläggningssystem på betong i parkeringshus och garage. Val av system, inverkan av betongkvalitet, underhålls- och reparationsåtgärder samt uppföljningar av befintliga system bör tas upp. En annan åt-gärd kan vara att även använda katodiskt skydd.
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| 18. |
- Edwards, Ylva, et al.
(author)
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ByggaBAD 2020
- 2012
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In: Badmästaren. ; :8, s. 34-35
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Journal article (other academic/artistic)
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| 19. |
- Edwards, Ylva, et al.
(author)
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Chemical resistance and wear for concrete protection systems to be used in biological treatment plants : Laboratory testing and results
- 2013
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In: Sustainable Construction Materials and Technologies. - : International Committee of the SCMT conferences. - 9789198009811 ; , s. 371-374
-
Conference paper (peer-reviewed)abstract
- This paper describes a project regarding degradation and corrosion problems for concrete at biological treatment plants in Sweden. An initial study shows that concrete used in such plants cannot resist attack by leachate from food waste, and therefore needs surface protection. In a second project part, requirements specification was developed trying to ensure the function of such protection products and systems, together with concrete, in different parts of a plant. The third part of the project involves laboratory testing of different types of products possibly suitable for the protection of concrete in biological treatment plants. Performance parameters studied and tested in the laboratory are chemical resistance and resistance to wear. Chemical resistance concerns acidic leachate water at temperatures up to 70°C. The laboratory study involves epoxy, polyurea, polyurethane, methyl methacrylate, vinyl ester, bituminous products and silica. Results and experience are reported, showing significant differences between types of material.
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| 20. |
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| 21. |
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| 22. |
- Edwards, Ylva, et al.
(author)
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Energy saving and environmental friendly wax concept for polymer modified mastic asphalt
- 2010
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In: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 43, s. 123-131
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Journal article (peer-reviewed)abstract
- This paper focuses on the addition of commercial wax as flow improver in polymer modified bitumen intended for use in mastic asphalt pavements under Nordic climatic conditions. Different aspects are dealt with. The aim of the project is to make mastic asphalt used in Sweden today (for bridges, parking decks etc.) more environment friendly and easier to handle. However, wax modification must not have any noticeable negative impact on the performance of mastic asphalt at medium and lower temperatures. The project involves laboratory testing of wax and polymer modified binder mixtures as well as mastic asphalt mixtures. Effects of adding two commercial waxes to one polymer modified bitumen have been studied. The results show that both waxes have a flow improving/viscosity depressant impact on the polymer modified bitumen at higher temperatures, indicating a possible lower laying temperature for the mastic asphalt if modified with such waxes. Moreover, there is a stiffening effect at medium and high temperatures (below placing temperature), indicating a certain positive effect on stability. Concerning low temperature performance, there are results indicating some negative impact on crack susceptibility at low temperatures, more by the addition of one of the waxes than by addition of the other. However, it could be concluded that using up to at least 4% of either wax additive will improve workability for the mastic asphalt product under investigation making it possible to lower working temperatures without seriously affecting its good performance in any negative way.
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| 23. |
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| 28. |
- Edwards, Ylva, et al.
(author)
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Garage och p-hus
- 2010
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In: Betong. - 1101-9190. ; :1, s. 32-35
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Journal article (other academic/artistic)
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| 29. |
- Edwards, Ylva
(author)
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Gjutasfalt : ett vackert och hållbart material i byggande
- 2012
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Reports (peer-reviewed)abstract
- Gjutasfalt har använts sen början av 1800-talet till beläggningar av olika slag. Till skillnad_x000D_ från konventionell asfaltbetong gjuts produkten ut i täta skikt i form av t.ex. golvbeläggning,_x000D_ isolering, takbeläggning, beläggningar på gator och trottoarer, på broar och parkeringsdäck._x000D_ Gjutningen kan utföras för hand eller med hjälp av gjutasfaltläggare. Gjutasfalt kan modifieras_x000D_ och/eller pigmenteras genom val av stenmaterial eller i olika färger för användning till_x000D_ dekorativa beläggningar på t.ex. torg eller i byggnader. Gjutasfalt kan även skulpteras och_x000D_ användas som konstmaterial._x000D_ Den största gjutasfaltmarknaden finns i Tyskland och Frankrike. Gjutasfalt används nästan_x000D_ inte alls i USA och Kanada, men användningen har däremot börjat växa på senare tid i Asien._x000D_ Två stora fördelar med gjutasfalt är slitstyrka och täthet. Gjutasfalt består av bitumen med_x000D_ eventuell tillsats av polymerer, blandat med välgraderat stenmaterial, filler, sand och i vissa_x000D_ fall även finmakadam. Genom tillsats av en rad additiv (tillsatsämnen) kan gjutasfaltens sammansättning_x000D_ varieras och anpassas för olika typer av applikationer och önskemål._x000D_ Gjutasfaltens sammansättning anpassas efter typ av applikation, mekanisk -, termisk - och_x000D_ kemisk belastning samt efter rådande klimatförhållanden på plats. Numera tillverkas gjutasfalt_x000D_ i specialutformade stationära industriella verk. I dessa proportioneras materialen, torkas eller_x000D_ upphettas stenmaterialet samt blandas de olika komponenterna under välkontrollerade förhållanden._x000D_ Modern arkitektur ställer höga krav, inte minst på golvbeläggningar, med individuell och elegant_x000D_ design i kombination med perfekt funktion. Slipad gjutasfalt, såsom Bitu Terrazzo® är_x000D_ ett innovativt beläggningsval t.o.m. i privatbostäder. Utläggningen går snabbt och golvet kan_x000D_ belastas på kort tid. Det är vidare fogfritt, hygieniskt, energisnålt, ljudabsorberande och lätt att_x000D_ rengöra. Genom individuellt urval av mineraler kan både struktur och färg hos beläggningen_x000D_ varieras. Med tillsats av färgat stenmaterial eller metall öppnas ytterligare designmöjligheter._x000D_ Diamantslipning i flera steg understryker gjutasfaltens karaktär och tidlösa elegans. Myckt_x000D_ hårt bitumen används i kombination med filler, sand och grövre stenmaterial. Tjockleken_x000D_ ligger mellan 3 och 4 cm._x000D_ I Sverige används gjutasfalt mest för broar, parkeringsdäck, gårdar och terrasser. För broar_x000D_ och parkeringsdäck används i huvudsak polymermodifierat bitumen. Exemplen på andra användningsområden_x000D_ och objekt från övriga Europa är emellertid många, ofta vackra och imponerande._x000D_ I rapporten beskrivs gjutasfaltens många möjligheter som hållbart, miljövänligt och inte minst_x000D_ vackert material i byggande av olika slag._x000D_ Rapporten visar att gjutasfaltmarknaden i Sverige bör kunna växa, utvecklas och förnyas avsevärt_x000D_ inte minst mot nya användningsområden .
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| 30. |
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| 31. |
- Edwards, Ylva
(author)
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Hållbara brobaneplattor - tätskikt : state of the art
- 2011
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Reports (peer-reviewed)abstract
- Skador på brobaneplattor av betong, främst till följd av kloridinducerad korrosion, är ett kost-samt problem över hela världen och har under lång tid varit föremål för omfattande forsk-nings- och utvecklingsinsatser. Att förse brobaneplattan med högkvalitativ isolering är därför en viktig åtgärd för längre livslängd hos betongbroar. Tätskiktets uppgift är att skydda be-tongen från i huvudsak vatten- och vägsaltinträngning, så att inte betong eller armering skadas och brons bärighet därmed reduceras. Andra möjligheter som provats som korrosions-hämmande åtgärd är epoxibehandlade armeringsjärn och katodiskt skydd. Även skydds-behandling av armering med zink och nickel förekommer, liksom rostfri armering (rostfritt stål) och armering av fiberförstärkt polymer. Slitlager av betong anses vara ett alternativ om slitbetongen kan göras tillräckligt tät och sprickfri. I norra Sverige, där vägarna normalt inte saltas vintertid och trafiken är låg, finns ett stort antal broar med slitbetong._x000D_ _x000D_ Rapporten behandlar olika typer av tätskikts- och beläggningssystem, med problem, möjlig-heter, för- och nackdelar. De idag vanligast förekommande typerna av material för tätskikt till brobaneplattor av betong har sammanställts. Här ingår system med tätskiktsmatta, asfaltmastix och flytapplicerat system av härdplasttyp (epoxi, akrylat, polyuretan och polyurea). I ett system med gjutasfalt som skydds- och/eller beläggningslager på tätskiktet kan även gjutasfalten räknas som tätskikt. Gjutasfalt beskrivs därför kortfattat i ett eget avsnitt. Betongunderlagets och primerns betydelse för tätskiktets funktion tas upp och diskuteras._x000D_ _x000D_ Regelverk i Sverige och andra länder tas upp liksom forskning samt forsknings- och utvecklingsbehov. Blåsbildning, uppföljning av befintliga tätskiktssystem, val av sprutapplicerade system, inverkan av betongkvalitet på tätskiktets funktion över tiden samt vidareutveckling av en del provningsmetodik, är förslag som tas upp i rapporten._x000D_ _x000D_ Underlag för LCC-analyser presenteras i form av materialkostnader och beräknad livslängd._x000D_ _x000D_ I slutsatserna konstateras bl.a. att: _x000D_ • Den vanligast förekommande typen av tätskikt i Europa idag är polymermodifierade bitumenbaserade tätskiktsmattor, ett system som ökat i användning under de senaste 20 åren. Även flyt¬applicerade system med härdplast ökar._x000D_ • Erfarenheten av flytande/sprutapplicerade tätskiktssystem på betongunderlag i Sverige är begränsad, och inga egentliga kravspecifikationen finns idag för vägbroar under Trafik-verkets ansvar._x000D_ • Tätskikts- och beläggningssystem med epoxiförsegling, tätskiktsmatta och beläggnings-lager av gjutasfalt ger det säkraste och mest hållbara systemet (under förutsättning att appliceringsarbetet utförs enligt gällande regler)._x000D_
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| 32. |
- Edwards, Ylva, et al.
(author)
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Influence of commercial waxes and polyphosphoric acid on bitumen and asphalt concrete performance at low and medium temperatures
- 2006
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In: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 39:7, s. 725-737
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Journal article (peer-reviewed)abstract
- The influence of adding four types of commercial wax and one polyphosphoric acid to a non-waxy bitumen was investigated with regard to binder and asphalt concrete mixture performance. Binder properties were determined using dynamic shear rheometer (DSR), bending beam rheometer, force ductilometer and various conventional test methods. Asphalt concrete performance was investigated using tensile stress restrained specimen test (TSRST), creep test at -25 degrees C, dynamic creep test at 40 degrees C and complex modulus test at 0, 10 and 20 degrees C. Totally eleven binders and eight asphalt mixtures were investigated. TSRST fracture temperatures of the asphalt mixtures were marginally influenced by the addition of any of the additives, and significant physical hardening of the binders, observed by BBR testing, could not be established using TSRST. Also in creep testing of asphalt mixtures at -25 degrees C, recorded effects were less pronounced compared to binder testing. In dynamic creep testing, the smallest permanent strains were recorded for the asphalt mixtures containing FT-paraffin or montan wax, indicating better resistance to rutting. Adding polyethylene wax or polyphosphoric acid to the non-waxy bitumen used, showed considerable positive stiffening effects on the binder at medium and higher temperatures. However, this increase in stiffness could not be shown in dynamic creep testing (at 40 degrees C) of asphalt concrete mixtures containing these additives.
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| 33. |
- Edwards, Ylva, et al.
(author)
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Influence of commercial waxes on bitumen aging properties
- 2005
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In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 19:6, s. 2519-2525
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Journal article (peer-reviewed)abstract
- Aging properties of wax-modified 160/220 bitumens and the influence of wax on these properties were evaluated using dynamic mechanical analysis (DMA), bending beam rheometer (BBR) analysis, force ductility testing, Fourier transform infrared (FTIR) spectroscopy, and thin-layer chromatography (TLC-FID). The binders were aged by means of the rolling thin-film oven test (RTFOT) and a pressure aging vessel (PAV). It was observed that aging resulted in oxidation of the bitumen (increase in carbonyl absorbance and in resin and/or asphaltene content by TLC-FID.) Changes in rheological properties of aged wax-modified binders depended on the base bitumen as well as on the type and amount of wax additive. Aging increased the complex modulus as well as elasticity, indicated by a decrease in phase angle at medium temperatures. For the polyethylene wax (PW)-modified binders, originally showing a large decrease in phase angle at higher temperature, this decrease was markedly reduced by aging, indicating network damage. Results and aging indexes obtained in this study indicate no or marginally positive influence of wax on bitumen aging properties.
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| 34. |
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| 35. |
- Edwards, Ylva, 1948-
(author)
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Influence of waxes on bitumen and asphalt concrete mixture performance
- 2005
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Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis consists of a literature review, presented in two papers, and another six papers describing experimental studies of the influence of different kinds of wax and polyphosporic acid on bitumen and asphalt concrete mixture properties. The literature review should give an extensive description of the field of knowledge concerning wax in bitumen. Effects of wax in crude oil, bitumen and asphalt concrete as well as test methods for studying these effects are described. Theories behind possible mechanisms are also discussed, and commercial wax as additive to bitumen for different purposes included. The experimental parts comprise laboratory studies involving totally five 160/220 penetration base bitumens from different sources, two isolated bitumen waxes, five commercial waxes and one polyphosphoric acid. Asphalt concrete slabs, containing base or modified bitumen were prepared and tested. Binder properties were evaluated using different types of laboratory equipment, such as dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimeter (DSC), force ductilometer, as well as equipment for determining conventional parameters like penetration, softening point, viscosity, and Fraass breaking point. Fourier Transform Infrared (FTIR) spectroscopy and Thin Layer Chromatography (TLC-FID) were used for chemical characterization. The binders were aged by means of the rolling thin film oven test (RTFOT) and pressure ageing vessel (PAV) in combination. Asphalt concrete properties were evaluated at low temperatures using the tensile strain restrained specimen test (TSRST) and creep test at -25°C. Dynamic creep testing was performed at 40°C, as well as complex modulus tests between 0 and 20°C. Binder test results indicated that the magnitude and type of effect on bitumen rheology depend on the bitumen itself, type of crystallizing fraction in the bitumen and/or type and amount of additive used. Bitumen composition was found to be of decisive importance. Adding polyethylene wax or polyphosphoric acid, especially to a non-waxy 160/220 penetration grade bitumen, showed no or positive effects on the rheological behaviour at low temperatures (decrease in stiffness) as well as medium and high temperatures (increase in complex modulus and decrease in phase angle). However, the corresponding positive effects could not be shown in dynamic creep testing (at 40°C) of asphalt concrete mixtures containing these modified binders. Adding FT-paraffin decreased the physical hardening index for all bitumens. Also polyethylene wax and montan wax showed this effect for some bitumens. Slack wax showed a large increasing effect on physical hardening, and polyphosphoric acid none or a minor negative effect. No correlation between physical hardening index (PHI) and wax content by DSC was found in this study, involving both natural bitumen wax and commercial wax. Addition of the commercial waxes used showed no or marginally positive influence on bitumen ageing properties for the bitumens and test conditions used. Comparing asphalt mixture test results to the corresponding binder test results, the effects on asphalt mixtures from adding commercial wax or polyphosphoric acid were less evident. Significant binder physical hardening by BBR could not be confirmed by TSRST.
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| 36. |
- Edwards, Ylva
(author)
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Influence of Waxes on Bitumen and Asphalt Concrete Mixture Performance
- 2009
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In: International Journal on Road Materials and Pavement Design. - 1468-0629 .- 2164-7402. ; 10:2, s. 313-335
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Journal article (peer-reviewed)abstract
- This paper deals with scientific work carried out to study the influence of different kinds of wax on bitumen and asphalt concrete mixture properties. Experimental parts involve base bitumens from different sources, isolated bitumen waxes and commercial waxes. Asphalt concrete slabs, containing base or wax modified bitumen were prepared and tested. Binder properties were evaluated using different types of laboratory equipment, such as dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimeter (DSC), as well as equipment for determining more conventional parameters. Asphalt concrete properties were evaluated at low temperatures using the tensile strain restrained specimen test (TSRST) and creep test at -25 degrees C At higher temperatures, dynamic creep testing was performed at 40 degrees C, and complex modulus tests between 0 and 20 degrees C Binder test results indicated that the magnitude and type of effect on bitumen rheology depend on the bitumen itself hype of crystallizing fraction in the bitumen and for type and amount of additive used. Adding polyethylene wax, showed no or positive effects on the rheological behaviour at low temperatures (decrease in stiffness) as well as medium and high temperatures (increase in complex modulus and decrease in phase angle). However, the corresponding positive effects could not be shown in dynamic creep testing (at 40 degrees C) of asphalt concrete mixtures containing these modified binders. Adding FT-paraffin decreased the physical hardening index (obtained using BBR) for all bitumens. Also polyethylene war and montan wax showed this effect for some bitumens. Slack wax showed a large increasing effect on physical hardening. No correlation between physical hardening index (PHI) and wax content by DSC was found in this study. Addition of commercial waxes used showed no or marginally positive influence on bitumen ageing properties for bitumens and test conditions used. Asphalt mixture test results were compared to the corresponding binder test results, and found to be less evident. Significant physical hardening by BBR could not be confirmed by TSRST.
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| 37. |
- Edwards, Ylva
(author)
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Influence of waxes on polymer modified mastic asphalt performance
- 2010
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In: PROCEEDINGS OF THE 4TH EURASPHALT AND EUROBITUME CONGRESS.
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Conference paper (peer-reviewed)abstract
- The use of wax additives in polymer modified coarse aggregate mastic asphalt in Europe is reviewed. Commercial wax such as FT-paraffin and montan wax are typical so-called bitumen flow improvers, which are used for asphalt pavements and mastic asphalt to reduce the mixing temperature and thereby energy consumption and emissions. Workability may be improved as well. These waxes differ a great deal from natural bitumen wax with respect to molecular weight and molecular weight distribution. They have high congealing points around 100degreesC and higher melting areas than natural wax in bitumen. Results are presented from an ongoing joint Swedish project about wax as flow improver in polymer modified bitumen for mastic asphalt production. Wax modification should not have any noticeable negative impact on the performance of mastic asphalt products at medium and lower temperatures. The project involves laboratory testing of wax and polymer modified binders and mastic asphalt mixtures, as well as field studies. Effects of adding two commercial waxes to one polymer modified bitumen are presented in this paper. The results show that both waxes have a flow improving/viscosity depressant impact on the polymer bitumen at higher temperatures, indicating a possible lower laying temperature for the mastic asphalt if modified with such waxes. Moreover, there is a stiffening effect at medium and high temperatures (below laying temperature), indicating a certain positive effect on stability. Concerning low temperature performance, there was a negative impact on crack susceptibility at low temperatures, which was larger with the addition of FT-paraffin than the addition of montan wax. For the covering abstract see ITRD E157233
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| 40. |
- Edwards, Ylva, et al.
(author)
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Kartläggning av vittrings- och korrosionsproblem vid hantering av matavfall : etapp III Verifiering av metodik
- 2012
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Reports (peer-reviewed)abstract
- Två inledande studier om vittrings- och korrosionsskador på betong i biologiska_x000D_ behandlingsanläggningar har genomförts under 2009/2010 inom Waste Refinery projekt_x000D_ WR-27 respektive WR-34. Resultaten visar att betong inte har tillräcklig motståndskraft i_x000D_ den aktuella aggressiva anläggningsmiljön. Vidare konstateras att någon form av_x000D_ tätskiktsbeläggning behövs för att säkerställa betongkonstruktionernas funktion, och att_x000D_ beläggningen måste tåla den aggressiva miljön och den trafik som förekommer på plats. Ett_x000D_ förslag till kravspecifikationer för tätskikt på betong i aggressiv matavfallsmiljö har därefter_x000D_ tagits fram och en tredje studie har föreslagits. Syftet med den tredje studien har varit att_x000D_ utvärdera och verifiera föreslagen provningsmetodik genom laboratorieprovning på utvalda_x000D_ produkter och system. Resultat från denna tredje studie redovisas i föreliggande rapport._x000D_ Metoderna avser resistens mot lakvatten i kombination med hög temperatur respektive_x000D_ slitage. Provningen har genomförts i samarbete med tillverkare och entreprenörer, vilka_x000D_ också bekostat sin egen provning. Innan den egentliga provningen kunde genomföras_x000D_ måste emellertid metodiken modifieras och anpassas till applikationen biologiska_x000D_ behandlingsanläggningar genom en förstudie. Målet med laboratoriestudien har varit att_x000D_ kunna leverera:_x000D_ Metodbeskrivning för provning av tätskiktbeläggningars resistens mot lakvatten i_x000D_ biologiska behandlingsanläggningar._x000D_ Metodbeskrivning för provning av tätskiktbeläggningars slitstyrka i biologiska_x000D_ behandlingsanläggningar._x000D_ Specifikation som skall kunna gälla specifikt för tätskikt på betong i biologiska_x000D_ behandlingsanläggningar._x000D_ Dessa mål har uppfyllts._x000D_ Provningsresultat vad gäller resistens mot lakvatten och resistens mot avnötning, enligt_x000D_ föreslagen metodik, redovisas i rapporten för ett stort antal produkter och system._x000D_ Resultaten varierar kraftigt för olika typer av system och anledningar till detta diskuteras_x000D_ relativt ingående._x000D_ Projektet förväntas följas av provläggningar i fält vid lämplig anläggning._x000D_ Slutligen kan nämnas att projektet även ansluter till ett SBUF-projekt (Svenska_x000D_ Byggbranschens Utvecklingsfond) som startats upp av gjutasfaltbranschen för_x000D_ genomförandet av provningar inom det aktuella Waste Refinery projektet, men också för_x000D_ mer ingående studier av ingående komponenter (stenmaterial och bindemedel) i utvalda_x000D_ gjutasfaltprodukter speciellt lämpade för biologiska behandlingsanläggningar, samt för_x000D_ kommande fältprovning. Id för SBUF-projektet är 12553.
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| 41. |
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| 46. |
- Edwards, Ylva
(author)
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Polymer modified bitumen for airfields : Pristina Airport
- 2007
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Conference paper (peer-reviewed)abstract
- Airfield pavements are exposed to special conditions such as the effects of runway and aircraft deicing chemicals, which may result in accelerated deterioration of the pavement. Aircraft safety may be jeopardised through stones loosening from the pavement, causing damage to aircraft engines. Accelerated deterioration of the pavement also shortens pavement life, resulting in increased capital costs. Special requirements therefore are needed for airfield pavements and binders used in such pavements. In Sweden, polymer modified bitumen frequently is used for asphalt concrete pavements on civil airfields. Special requirements specifications based on climatic conditions have been developed for such binders to ensure good performance as well as good resistance to deicing chemicals. Within a project run by Swedavia, renovation was carried out since spring 2004 at Pristina airport in Kosovo. The selection of bitumen is based on climatic conditions in the Kosovo area and Swedish experience of polymer modified binders for airfields since 1998. For the wearing course, the selected binder will be polymer modified bitumen fulfilling the requirements of PG (Performance Grade) 76-22 according to SHRP (Strategic Highway Research Program) with certain additional tests and requirements. In this paper, Swedish experience of polymer modified binders for airfields is summarized and the binder design for Pristina airport discussed. For the covering abstract see ITRD E139491.
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| 47. |
- Edwards, Ylva, et al.
(author)
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Polymer modified waterproofing and pavement system for the High Coast bridge in Sweden : Research, testing and experience
- 2001
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Reports (pop. science, debate, etc.)abstract
- The High Coast Bridge is one of the world´s longest suspension bridges. Thewaterproofing andpavement for this bridge had to be chosen with care. A lowest averagetemperature of -–20°C, a minimumtemperature of -–40°C and a maximum temperature of +30°C have been recorded inthis reigon ofSweden.To be able to recommend the most suitable system for the bridge, a researchproject was started by theSwedish National Road Administration as early as 1992. As a result ofresearch and testing during theproject period, a suitable system for the bridge was suggested by the SwedishRoad Administration in1996.The waterproofing and pavement system chosen for the High Coast bridgeconsists of an epoxyprimer system, an SBS-modified bituminous sheet layer, coarse aggregatemastic asphalt with SBSmodifiedbitumen and split mastic asphalt with SBS-modified bitumen and fibres.Various waterproofing and pavement producst and systems were tested in theresearch project, bothseparately and in different combinations for evaluation.Laboratory testing was performed at the Swedish National Road and TransportResearch Institute(VTI), starting in 1992. Testing covered characteristics and performance ofthe various products andsystems at low and high temperatures. Important parameters studied for totalbuilt-up systems includedadhesion (to steel deck and between layers), shear and sliding resistance.Systems with SBS-modified bituminous sheet (3.5 mm thick), SBS-modified fineaggregate masticasphalt (4 mm) and conventional fine aggregate mastic asphalt (4 mm) werecompared.In 1993, eight different systems were laid on a steel bridge at Pitsund(further north than the HighCoast Bridge) for evaluation on site and laboratory testing at VTI.Fatigue tests of the entire waterproofing and pavement system were performedfor four possiblesystems and the reference system at the Otto Graf Institute (FMPA) inStuttgart. Testing was performedin accordance with the German ZTV-BEL ST-92 “Dauerschwellbiegeprüfung”, butat temperatures from-–30°C to+3°C.The public procurement was completed in July 1996. The system was laid duringlate summer andautumn of 1997.Quality control testing was performed. Samples of all products used weretaken during work on thebridge.
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