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Influence of waxes on bitumen and asphalt concrete mixture performance
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , iii, 48 p.
Series
Trita-VT. FR, ISSN 1650-867X ; 2005:1
Keyword [en]
bitumen, asphalt, additives, wax in bitumen, polyphosphoric acid in bitumen, rheology, IR-spectroscopy, dynamic mechanic analysis (DMA), bending beam rheometer (BBR), literature study, low temperature physical hardening, highway materials, morphology, modified bitumens, temperature susceptibility, low temperature performance, ageing, microscopy, chromatography, Fourier transform infrared spectroscopy, force ductility, conventional binder tests, asphalt performance, tensile strain restrained specimen test (TSRST)
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-553OAI: oai:DiVA.org:kth-553DiVA: diva2:14419
Public defence
2005-12-16, Sal E1, Lindstedtsvägen 3, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20101006Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2010-10-06Bibliographically approved
List of papers
1. Wax in bitumen: Part 1: Classifications and General Aspects
Open this publication in new window or tab >>Wax in bitumen: Part 1: Classifications and General Aspects
2005 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 6, no 3, 281-309 p.Article in journal (Refereed) Published
Abstract [en]

Wax in bitumen has for a long time been of great interest, particularly regarding effects on bitumen quality and methods for determining wax content. Opinions about wax in bitumen have varied over the years and sometimes been contradictory. The findings of a literature study are presented in two companion papers. The main intention of the study was to give an extensive description ofthe field of knowledge concerning wax in bitumen. In this paper, classifications and general aspects on effects of wax in crude oil and bitumen are described. Theories behind possible mechanisms are also discussed, and commercial wax as additive to bitumen for different purposes described. Effects of wax are influenced by chemical composition and rheological properties of the bitumen, amount of wax in the bitumen as well as chemical composition and crystalline structure of the wax. The effect of wax on bitumen is linked to its crystallinity and melting properties. The temperature range of application as well as the definition of wax in bitumen is also of great importance. The presence of large wax crystals (macrocrystalline wax) in bitumen is considered to be most problematic. However, waxes in bitumen generally are microcrystalline and/or amorphous and can contain branched, alicyclic and aromatic components with heteroatoms, which renders crystallization considerably more difficult.

Keyword
bitumen wax, state-of-the-art, chemical composition
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8925 (URN)10.3166/rmpd.6.281-309 (DOI)000233195200001 ()2-s2.0-33845672724 (Scopus ID)
Note
QC 20101006Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
2. Wax in bitumen: Part II: Characterization and Effects
Open this publication in new window or tab >>Wax in bitumen: Part II: Characterization and Effects
2005 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 6, no 4, 439-468 p.Article in journal (Refereed) Published
Abstract [en]

A large number of different methods for isolating and characterizing wax in bitumen, as well as for determination of wax content, have been used over the years. The methods used for determining wax content all give different results for one and the same bitumen, which has caused problems for many years. Through different types of phase transition, wax in bitumen influences bitumen properties to a larger or minor extent. In some cases, such an influence may give rise to negative effects like increased sensitivity to cracking or plastic deformation in asphalt concrete pavements. In other cases, wax may even show positive effects on bitumen, such as increased stiffness at higher temperatures, leading to improved resistance to rutting. This paper is the second of two companion papers discussing the field of knowledge concerning wax in bitumen. In the first paper, classifications and general aspects on effects of wax in crude oil and bitumen are described.

Keyword
bitumen wax, state-of-the-art, rheology, test methods
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8926 (URN)10.3166/rmpd.6.439-468 (DOI)000233545600001 ()2-s2.0-33845664581 (Scopus ID)
Note
QC 20101006. Uppdaterad från in press till published (20101006).Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
3. Rheological effects of waxes in bitumen
Open this publication in new window or tab >>Rheological effects of waxes in bitumen
2003 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 17, no 3, 511-520 p.Article in journal (Refereed) Published
Abstract [en]

Rheological effects of adding two bitumen waxes (isolated from SEC-II fraction) to three bitumens were studied using dynamic mechanical analysis (DMA). Also, a commercially available slack wax was used in the study. The results show that the magnitude and type of effect on bitumen rheology depend on the bitumen and type of crystallizing fraction in the bitumen. Effects due to wax content shown in DMA temperature sweeps are well related to the corresponding effects shown in DSC thermograms. The slope of the logarithm of the complex modulus between 25 degreesC and 60 degreesC is introduced as a possible proper factor for predicting rutting sensitivity due to wax content.

Keyword
Addition reactions, Crystallization, Dynamic mechanical analysis, Elastic moduli, Rheology, Sensitivity analysis, Temperature, Bitumen, Crystallizing fraction, Rheological effects, Rutting sensitivity
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8927 (URN)10.1021/ef020202b (DOI)000183089500001 ()
Note
QC 20101006Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
4. Rheological effects of commercial waxes and polyphosphoric acid in bitumen 160/220: High and medium temperature performance
Open this publication in new window or tab >>Rheological effects of commercial waxes and polyphosphoric acid in bitumen 160/220: High and medium temperature performance
2007 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 21, no 10, 1899-1908 p.Article in journal (Refereed) Published
Abstract [en]

The effects of adding three commercial waxes and a polyphosphoric acid to three bitumens of 160/220 penetration grade were studied using different types of laboratory equipment, such as Dynamic Shear Rheometer (DSR), Differential Scanning Calorimeter (DSC), Force Ductilometer (FD) as well as equipment for determining conventional parameters like penetration, softening point and Fraass breaking point. The paper deals with effects at medium and high in-service temperatures likely to affect the rutting performance of an asphalt concrete pavement. The results show that magnitude and type of effect on bitumen theology depend on the bitumen as well as 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 bitumen, showed considerable positive effects on the theological behaviour at medium and higher temperatures.

Keyword
bitumen rheology, wax, polyphosphoric acid, dynamic shear rheometer, differential scanning calorimeter
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8928 (URN)10.1016/j.conbuildmat.2006.07.012 (DOI)000248778100001 ()2-s2.0-34250862062 (Scopus ID)
Note
QC 20101006. Uppdaterad från submitted till published (20101006).Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
5. Rheological effects of commercial waxes and polyphosphoric acid in bitumen 160/220: low temperature performance
Open this publication in new window or tab >>Rheological effects of commercial waxes and polyphosphoric acid in bitumen 160/220: low temperature performance
2006 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 85, no 7-8, 989-997 p.Article in journal (Refereed) Published
Abstract [en]

Effects of adding three commercial waxes and a polyphosphoric acid to three bitumens of 160/220 penetration grade were studied using different types of laboratory equipment, such as dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimeter (DSC), force ductilometer (FD) as well as equipment for determining conventional parameters like penetration, softening point and Fraass breaking point. The paper deals with low-temperature effects, which could influence the thermal cracking resistance of asphalt concrete pavements. The results show that magnitude and type of effect on bitumen rheology depend on the bitumen itself as well as type and amount of additive used. Bitumen composition was found to be of decisive importance. Adding polyethylene wax or polyphosphoric acid, especially to nonwaxy 160/220-penetration grade bitumen, showed positive effects on the rheological behaviour at low temperatures.

Keyword
bitumen rheology, wax, polyphosphoric acid
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-25034 (URN)10.1016/j.fuel.2005.09.014 (DOI)000235648600012 ()2-s2.0-29744459909 (Scopus ID)
Note
QC 20101006Available from: 2010-10-06 Created: 2010-10-06 Last updated: 2017-12-12Bibliographically approved
6. Influence of commercial waxes on bitumen aging properties
Open this publication in new window or tab >>Influence of commercial waxes on bitumen aging properties
2005 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 19, no 6, 2519-2525 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Aging of materials, Dynamic mechanical analysis, Elasticity, Fourier transform infrared spectroscopy, Oxidation, Polyethylenes, Rheology, Rheometers, Thin layer chromatography, Aging properties, Bending beam rheometer (BBR) analysis, Bitumens, Force ductility testing, Polyethylene wax (PW)-modified binders, Pressure aging vessel (PAV), Rolling thin-film oven test (RTFOT)
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8929 (URN)10.1021/ef050166r (DOI)000233419100042 ()2-s2.0-29044437191 (Scopus ID)
Note
QC 20101006. Uppdaterad från in press till published (20101006).Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
7. Effects of commercial waxes on asphalt concrete mixtures performance at low and medium temperatures
Open this publication in new window or tab >>Effects of commercial waxes on asphalt concrete mixtures performance at low and medium temperatures
2006 (English)In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 45, no 1, 31-41 p.Article in journal (Refereed) Published
Keyword
bitumen wax, asphalt mixtures, rheology, low temperature cracking, TSRST, dynamic creep
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8930 (URN)10.1016/j.coldregions.2006.01.002 (DOI)000238183200004 ()2-s2.0-33646469720 (Scopus ID)
Note
QC 20101006. Uppdaterad från submitted till published (20101006).Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved
8. Influence of commercial waxes and polyphosphoric acid on bitumen and asphalt concrete performance at low and medium temperatures
Open this publication in new window or tab >>Influence of commercial waxes and polyphosphoric acid on bitumen and asphalt concrete performance at low and medium temperatures
2006 (English)In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 39, no 7, 725-737 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Additives, Asphalt, Binders, Concretes, Creep, Fracture, Low temperature effects, Rheology, Stiffness, Strain, Waxes, Bending beam rheometer, Dynamic shear rheometer (DSR), Force ductilometer, Polyphosphoric acid, Tensile stress restrained specimen test (TSRST)
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-8931 (URN)10.1617/s11527-006-9134-8 (DOI)000243151500006 ()2-s2.0-33747091314 (Scopus ID)
Note
QC 20101006. Uppdaterad från submitted till published (20101006).Available from: 2005-01-08 Created: 2005-01-08 Last updated: 2017-12-14Bibliographically approved

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