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- 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. |
- 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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| 6. |
- 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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| 8. |
- 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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| 9. |
- 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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