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Binders Trevor Distin

Learn about the latest developments in road binders, including the use of crumb rubber binders and polymer-modified bitumen emulsions, as well as strategies for overcoming bitumen supply challenges in Southern Africa. Discover insights on performance-based binder specifications and innovative techniques for improving road durability.

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Binders Trevor Distin

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  1. Binders Trevor Distin

  2. Learn more about Use of crumb rubber binder CRB in seals and asphalt Use of polymer modified bitumen emulsions in seals Development of performance based specifications for binders

  3. Bitumen supply • RSA has traditionally been a net exporter of bitumen • Current demand exceeds 450,000 tonnes pa • Experiencing shortfalls due to: • unplanned refinery shut down • increase peak demand • limited storage facilities • green fuels specifications • Refineries supply penetration and cutback grades

  4. Sasol Sasolburg Secunda Crude oil refinery Natref Enref Synfuel plant Sapref Mosgas Calref Bitumen supply Messina Windhoek Pietersburg Gaborone Pretoria Maputo Johannesburg Mbabane Richards Bay Kimberly Bloemfontein Pofadder Maseru Durban Saldanha East London Port Elizabeth Cape Town Mossel Bay

  5. Refinery bitumen grades

  6. Comparison of specs Penetration ranges @ 25 ⁰C Viscosity ranges @ 60⁰C

  7. SANS 307 framework Low Temp Ave. Service Hot Mixing & Cracking Temperature Summer Compaction Consistency Pen R&B Visc @ Visc @ 60 C 135 C 0 25 50 75 100 125 150 Temperature (degC) After aging Before aging

  8. Development of PG specs • Link binder properties to pavement performance • Develop a ‘simple’ performance grade specification • Seamless test regime across all types and grades of binders for seals & asphalt • Using following performance criteria and tests: • Stiffness (G*) and elastic behaviour (phase angle) with the dynamic shear rheometer at maximum in-service temperature • Short term aging temperature susceptibility using dynamic viscosity after RTFOT • Long term aging performance using PAV and DSR

  9. RTFOT ageing of SBS G*/Sinδ Softening point

  10. Polymer blind spec Based on achieving end binder properties Covers both hot and cold PMB’s use in: Spray seals Asphalt Microsurfacing Crack sealants Bond coats Modified binders

  11. Modified binders

  12. Crumb rubber bitumen TG1 has specifications for CRB for use in seals & asphalt # 30 mesh crumb rubber used

  13. Properties of bitumen rubber

  14. Viscosity with time vs temp Hand held Rion

  15. Manufacture of CRB

  16. Digestion of CRB Spray with belly auger Compartment tank

  17. New construction Priming Invert cutback Oil in water Tack/bond coats Ultra thin asphalt Spray sealing in winter Tack spray Penetration spray Cover spray Rehab & maintenance In-situ stabilisation Enrichment sprays Dilute emulsion Proprietary cutback emulsions Slurry & microsurfacing Rutfilling Texture treatments overlays Cold mix asphalt Cold pour crack sealants Use of emulsions

  18. Use of PMBE’s

  19. Curing of Cationic Emulsion + latex droplet + + + - + - - - Strong chemical attraction - + - + - - - - + aggregate bitumen droplet 3 phase emulsion

  20. Spray sealing Construction of Cape seals Cover sprays Use emulsions allows construction of seals when road surface temperatures >10°C

  21. Overlays Rutfilling Microsurfacing

  22. Cost effectiveness of enrichment sprays Prolong life of existing seal by ± 3 years Apply up to 3 times before resealing

  23. Seal Type Distribution(Western Cape 6 – year average)

  24. Hardening/ Oxidation (WCPA) S-E1 SC-E1 S-R1

  25. Summary • Increased use of CRB for improved performance • Only high speed field blended CRB use in spray seals • On-site measurement of viscosity before use • Augers in digestion tanks & sprayers • >20 % rubber crumb used • Use of preblended CRB for asphalt wearing courses

  26. Summary • Increased use of emulsions • To allow construction of new seals in winter • Dilute sprays used to enriched aged seals to extend service life • Development of PG specs for binders • Use of DSR to measure binder properties across temperature spectrum • More suitable for measuring PMB degradation after RTFOT

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