1 / 64

Bitumen Wax & Impact on Asphalt Performance Good or bad?

Bitumen Wax & Impact on Asphalt Performance Good or bad?. Per Redelius and Xiaohu Lu Nynas Bitumen. NaBin Seminar October 26 2004. Definition of wax in bitumen? All materials in bitumen, which crystallise on cooling

hunter
Download Presentation

Bitumen Wax & Impact on Asphalt Performance Good or bad?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Bitumen Wax & Impact on Asphalt Performance Good or bad? Per Redelius and Xiaohu Lu Nynas Bitumen NaBin Seminar October 26 2004 Nynas Bitumen R&D

  2. Definition of wax in bitumen? • All materials in bitumen, which crystallise on cooling • Paraffin wax (or macrocrystalline wax): n-paraffins with few or no branches • Microcrystalline wax: aliphatic hydrocarbons with considerable amount of iso- and cycloparaffins • Aromatic molecules or molecules with polar functional groups showing ability to crystallise upon cooling Nynas Bitumen R&D

  3. Definition of wax in bitumen Wax in bitumen could be: • Natural wax which is present in the crude oil (Bitumen produced from waxy crudes) • Wax unintentionally produced through refining procedures like visbreaking or hydrocracking • Synthetic wax added to bitumen to change certain properties. This presentation is limited to “natural wax”. Nynas Bitumen R&D

  4. Impacts of Waxy Bitumen on asphalt performance? • Melting of wax at high temperatures (60oC) • - decrease in viscosity  more sensitive to rutting • Crystallisation of wax at low temperatures • - increase in stiffness, physical hardening  more sensitive to low temperature cracking • Poor adhesion to aggregates (stripping) • Wax crystals  reduced cohesion (effect on fatigue?) • … ... Nynas Bitumen R&D

  5. Project Overview • Determination of wax content of bitumen (I) • Isolation and chemical characterisation of wax (II) • Wax morphology (III) • Rheological study (IV) • Impact of wax on asphalt performance (V) Nynas Bitumen R&D

  6. Determination of Wax Content of Bitumen • Differential scanning calorimetry (DSC) • EN 12606-1 (DIN 52015) • Wax from IEC neutral fraction • Wax from SEC II Nynas Bitumen R&D

  7. Differential scanning calorimetry (DSC) Nynas Bitumen R&D

  8. Size Exclusion Chromatography (SEC) SEC-I: the most polar and associating components (“dispersed phases” or “asphaltenes”) SEC-II: non-associating components (“bitumen solvent moieties”) Precipitation of wax at -20°C from SEC-II (toluene/methyl ethyl ketone) Nynas Bitumen R&D Toluene

  9. Comparison of Wax Contents Determined by Different Methods Nynas Bitumen R&D

  10. 6 y = 0.23x + 0.61 4 2 R = 0.55 Paraffin by EN12606-1 (%) 2 0 0 2 4 6 8 Wax by DSC (%) Correlation between DSC and EN12606-1 Method Nynas Bitumen R&D

  11. Test Methods Crystal. Temp. Test methods SEC EN higher lower • Paraffin wax (macrocrystalline wax) • Microcrystalline wax (iso- and cycloparaffins) • Waxes with aromatic or polar groups DSC Nynas Bitumen R&D

  12. Chemical Characterisation of Wax Isolated from Bitumens • Differential scanning calorimetry (DSC) • Gas chromatography and mass spectrometry (GC-MS) • High temperature gas chromatography (HTGC) • Wide angle X-ray scattering (WAXD) • Gel permeation chromatography (GPC) • Thin layer chromatography with flame ionisation detection (TLC-FID) • Fourier transform infrared spectroscopy (FTIR) • Ultraviolet and visible spectroscopy (UV-Vis) Nynas Bitumen R&D

  13. Differential Scanning Calorimetry (DSC) of wax isolated from bitumen through the SEC procedure- 38ºC & 63ºC, 101J/g 61ºC, 64J/g Nynas Bitumen R&D

  14. n-C23 GC-MS: Wax from G40-96 Nynas Bitumen R&D

  15. Isolated Waxes n-Paraffins WG36 C18-C54, 10% WG37 C21-C52, 40% WG38 C18-C53, 18% WG40 C18-C58, 47% WG67 C18-C54, 23% Nynas Bitumen R&D

  16. Conclusions (I) • Wax (content) determination is method dependent; • Waxes differ in crystallisation/melting process, and in enthalpy; • Waxes differ in the content and distribution of n-paraffins; • Waxes also contain other materials, such as iso-paraffins, mono-, and di-naphthenes, and aromatics. Nynas Bitumen R&D

  17. Wax Morphology • Development of methodology • Classification of wax crystals • Effects of time and temperature • Temperature cycling • Freezing and melting experiments Nynas Bitumen R&D

  18. Techniques for Studying Wax Morphology • Polarised Light Microscopy (PLM) • Confocal Laser Scanning Microscopy (CLSM) • Freeze Fracture - Transmission Electron Microscopy (FF-TEM) Nynas Bitumen R&D

  19. Polarised Light Microscopy (PLM) 1h heat at 120°C & homogenise Slides at room temp. for 1h • Wax crystals in bitumen are anisotropic, which appear bright in PLM • Using transmitted light, sample has to be thin enough to let light pass through (10 m) • Crystals have to be large enough to be detectable (1 m) Nynas Bitumen R&D

  20. Confocal Laser Scanning Microscope (CLSM) Slides Metal cup • Scan the specimen with an illuminating spot (laser) • A small pinhole in front of detector • Controllable depth of field • Applicable to thin and thick specimen • Reflective light used to record images Nynas Bitumen R&D

  21. PLM CLSM FF-TEM U1393-02 10 m 10 m 100 nm T8-00 10 m 10 m 100 nm Nynas Bitumen R&D

  22. 2% wax G40-96 T63-02 T76-02 4% wax G36-96 G38-96 T9-00 Nynas Bitumen R&D

  23. Elongated Spots: G40-96 Crescents: T63-02 Flakes: T9-00 T8-00 Nynas Bitumen R&D

  24. Effect of Crystallisation Time and Temperature • Temperatures: -19°C, 0°C, 22°C, 40°C • Time: 1h, 4h, 24h • New sample for each temperature-time combination • Same temperatures for taking micro-photos and • for crystallisation Nynas Bitumen R&D

  25. 0ºC 22ºC 40°C 1 h 24 h Nynas Bitumen R&D

  26. After 1h crystallisation at 22°C, heat the sample to 60°C at 10°C/min 60°C after 15 min Heating to 80°C for 15 min 60°C after 30 min Nynas Bitumen R&D

  27. Conclusions (II) • Waxy bitumens may differ in waxy morphology; • The size and shape of wax crystals are not related to wax content; • The time and temperature show great effects on wax morphology; • At low temperatures, the time for visible wax crystals is longer and the • crystals are smaller as compared with crystallisation at room temperature. • At high temperatures, few crystals with large size are detected. • With increasing time, the wax crystals become more distinct. • For the bitumens studied, the temperatures for complete melting of wax • crystals are found between 40 and 80°C. Nynas Bitumen R&D

  28. Impact of Wax on Asphalt Performance • - Rutting • - Low temperature cracking • - Water sensitivity Nynas Bitumen R&D

  29. Nynas Bitumen R&D

  30. T8-00 Nynas Bitumen R&D

  31. f = 0.05 Hz Nynas Bitumen R&D

  32. Correlation between ZSV and SHRP rutting parameter Nynas Bitumen R&D

  33. 3000 50/70 grade 2500 70/100 grade 160/220 grade 2000 1500 G*/sin(delta) at 60°C and 10 rad/s (Pa) 1000 500 0 0 2 4 6 8 Wax Content (%) Nynas Bitumen R&D

  34. Nynas Bitumen R&D

  35. Nynas Bitumen R&D

  36. Wax (%) 2.3 0 4.1 6.2 0 2.4 2.9 4.1 4.2 Pen 65 83 101 86 196 214 181 180 180 Nynas Bitumen R&D

  37. Wax (%) 2.3 0 4.1 6.2 0 2.4 2.9 4.1 4.2 Pen 65 83 101 86 196 214 181 180 180 Nynas Bitumen R&D

  38. Mixture rutting (after 1500 wheel passes) versus bitumen softening point Nynas Bitumen R&D

  39. Mixture rutting (after 1500 wheel passes) versus bitumen dynamic viscosity Nynas Bitumen R&D

  40. Mixture rutting (after 1500 wheel passes) versus bitumen G*/sin (delta) and ZSV Nynas Bitumen R&D

  41. Low Temperature Properties • Binders • Glass transition temperature by DSC • Creep test by bending beam rheometer (BBR) • Isothermal physical hardening • Asphalt mixtures • Thermal stress restrained specimen test (TSRST) Nynas Bitumen R&D

  42. Binder creep test with BBR Physical hardening Nynas Bitumen R&D

  43. LST for 160/220 bitumens Nynas Bitumen R&D

  44. Nynas Bitumen R&D

  45. Thermal Stress Restrained Specimen Test (TSRST) Nynas Bitumen R&D

  46. Mixture test (TSRST): fracture temperature vs wax content Nynas Bitumen R&D

  47. Mixture test (TSRST): fracture strength vs wax content Nynas Bitumen R&D

  48. Nynas Bitumen R&D

  49. Nynas Bitumen R&D

  50. Comparison of Water Sensitivity of Asphalt Mixtures Wax in bitumen 2.3 0 4.1 6.2 0 2.4 2.9 4.1 4.2 (%, by DSC) Penetration 65 83 101 86 196 214 181 180 180 Nynas Bitumen R&D

More Related