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An introduction to emulsion technology.ppt
- 1. Shell Global Solutions Emulsion Technology by Frits de Jonge Shell Global Solutions, Singapore
- 2. Shell Global Solutions Cutbacks and Emulsions largely used in Spray Applications: • Primer coats • Tack coats • Surface Dressing (or Chip Seal, or Surface Seal, or Spray Seal, or Surface treatment, or ....................)
- 5. Shell Global Solutions Function of Surface Treatment - waterproof the pavement - provide dust free surface - provide wear resistant surface - provide skid resistant surface
- 7. Shell Global Solutions Prime Coatings
- 9. Shell Global Solutions Surface Dressings • Single surface dressing - Spray and chip • Multiple surface dressings - Sandwich (chip/spray/chip) - racked in (spray/chip/chip) - triple (spray>chip>spray>chip - cape seal (single seal/slurry seal)
- 12. Shell Global Solutions Spray Seal Design Aggregate Spread Rate - Over Spread Minimum Binder Contact ALD Maximum Binder Contact Correct Spread Rate
- 13. Shell Global Solutions Surface Treatments Performance problems • Chipping loss - Short term - Long term - Localised • Smooth surface - polishing , embedment • Bitumen rich surface - fatting up - bleeding
- 16. Shell Global Solutions Slurry Seal • Versatile • Quick & easy • Rapid trafficking • Preventive maintenance • Corrective maintenance • Aesthetic value • Economical
- 17. Shell Global Solutions Details slurry seal / microsurfacing equipment
- 20. Shell Global Solutions - 1st generation, simple chemistry systems slow break, slow set, Low Traffic Intensity open to traffic > 7h - 2nd generation, complex chemistry slow break, but fast set, Medium Traffic Intensity open to traffic 2h - 3rd generation, special complex chemistry, polymer modified system, slow break and fast set microsurfacing for High Traffic Intensity (Expressway) open to traffic < 1 h Slurry Seal Techniques
- 25. Shell Global Solutions Bitumen Emulsions - Key Aspects Critical for Emulsion stability viscosity pumpabilty/spraying breaking rate film formation / coating adhesion Critical for Binder emulsifiability fatting up crack arresting/cohesion adhesion durability Binder Options paving grades premium binders
- 26. Shell Global Solutions Binder Adhesion / Cohesion
- 27. Shell Global Solutions Bitumen emulsion production bitumen water emulsifier (acid, additives) bitumen emulsion ~50 °C 145 - 160 °C ~80 °C Production parameters • colloid mill type • gap width • rotor speed (6000, 9000 rpm) • rotor/stator (grooved, smooth) • temperatures
- 28. Shell Global Solutions Some typical cationic emulsifier systems R - NH - (CH2)3 - NH2 Diamine Rapid Polyamine R - (NH - (CH2)3)n - NH2 Medium/Slow Emulsion class basic formula Amido amine R - CO - NH - (CH2)3 - NH2 Medium/Slow Imidazolin e Rapid/Mediu m H R - C N - CH2 N - CH2 Quartenary ammonium R - N - CH3 R CH3 + Medium/Slow
- 29. Shell Global Solutions Bitumen emulsion - role of the emulsifier • Reduce interfacial tension (dynamic interfacial tension) • Facilitate droplet formation and break-up • Reduce coalescence • stabilisation by electrostatic repulsion • electrical double layer (z-potential) • presence of micelles
- 30. Shell Global Solutions Bitumen emulsions approach Bitumen manufacturing From crude oil to emulsion grade bitumen emulsifiability, stability Emulsion production Settling, viscosity, breaking, adhesion consistancy in quality Application on road Coating, breaking, stiffness build-up Fit-for-purpose in local situations » Traffic density, load, weather conditions, local aggregates, dustiness aggregates
- 31. Shell Global Solutions Bitumen Emulsion - Sedimentation • Based on stokes formula: v = g d2 (rb - rw) / 18 hc
- 32. Shell Global Solutions Bitumen emulsion viscosity • Particle size distribution • Packing density fm d n(d) bitumen content f viscosity h • Effective volume fraction ‘trapped’ water phase h h h 0 1 m m Dougherty-Krieger • Salt content, interfacial tension, polarity
- 33. Shell Global Solutions Water content in bitumen emulsion • Dean-stark distillation - total water content • Differential scanning calorimetry - continuous phase water -200 -150 -100 -50 0 50 100 -55 -45 -35 -25 -15 -5 5 15 25 Temperature (°C) Heat Flow Endo Up (mW) melting peak total water crystallisation peak 'free' water crystallisation peak 'trapped' water
- 34. Shell Global Solutions Model for bitumen emulsion setting Phase 1 Aggregate is wetted with emulsion still intact. Emulsion droplets and aggregate particles can move freely. Emulsion can be distributed to obtain homogeneous mixture and good coating.
- 35. Shell Global Solutions Model for bitumen emulsion setting Phase 2 Phase 3 The emulsion droplets start to coalesce. The droplets are still well recognisable. The emulsion droplets are fixed on the surface of the aggregate and cannot move freely anymore. The conglomerates have coalesced and no individual emulsion droplets canbe seen. The emulsion is broken and the bitumen phase has separated from the water. The aggregate should be fully coated with good adhesion. This state is the “cheesy” state. Mixes are crumble-like.
- 36. Shell Global Solutions Model for bitumen emulsion setting Phase 4 Phase 5 The islands of bitumen phase are linked and start to produce cohesion. This is the first phase in which the bitumen forms a continuous phase. The danger is that water can become trapped. In this last phase the bitumen film is continuous and full adhesion and cohesion are developed. It will take some time before all the water has been evaporated.
- 37. Shell Global Solutions Adhesion and cohesion build-up
- 39. Shell Global Solutions Bitumen emulsion applications balance in properties application In service bitumen film formation abrasion resistance emulsion spraying no settling,no run-off stability fast breaking,adhesion workability slow breaking emulsion mix voids,stiffness fast breaking,coating,adhesion Surface dressing Asphalt mixes
- 40. Shell Global Solutions Emulsion Product Services Selection of base bitumen Selection of effective, efficient emulsion recipes Production of high quality ‘fit for purpose’ emulsion - specification (storage stability, viscosity) - fast breaking, e.g. tack coating - slow breaking, e.g. primer sealing, cold mixes - special, e.g. slurry seal
- 41. Shell Global Solutions Emulsion Product Services Product application ‘the code of practice’ - emulsion storage and handling advice - recommendation on application conditions - performance recommendation and testing field samples aggregate analysis (gradation, sand equivalent) emulsion/aggregate mix testing (coating, breaking, cohesion, wet track abrasion)