Chapter 7 Fog and Rejuvenating Seals

1. Chapter 7Fog and Rejuvenating Seals From… Maintenance Technical Advisory Guide (MTAG)

2. Manager’s Overview From… Maintenance Technical Advisory Guide (MTAG)

3. Introduction to Fog/Rejuvenating Seals • What are Fog and Rejuvenating Seals? • Why use them? • When to use them? • Where to use them?

4. What is a Fog Seal? A mixture of asphalt emulsion and water applied to the asphalt surface of a road, street or highway. The primary purpose is to seal the road surface and defer surface degradation.

5. Fog Seals - Description • Light application of diluted slow-setting asphalt emulsion • Common uses • Seal aged surface • Improve lane delineation • Cost: 0.15 to 0.20 $/m2 (0.12 to 0.17 $/yd2) • Typical treatment life: 1 to 2 years

6. A Fog Seal Job

7. Why Use Fog Seal? • An inexpensive way of arresting raveling and adding binder back to aged surfaces • Fog seals are also useful in chip seal applications to hold chips in place in fresh seal coats to help prevent vehicle damage arising from flying chips • improve sealing or waterproofing • improve the surface appearance

8. When to Use Fog Seal? • Pavement surface condition – Dry mixes, high air voids, and surfaces showing minor and/or moderate raveling. • When chip seals are in need to prevent aggregate loss. • Pavement age – relatively newer pavement (not more than 2 years in service)

9. Where to Use Fog Seal? • Pavement surface condition – Dry mixes, high air voids, and surfaces showing minor and/or moderate raveling. • Pavement surface mix – can be used on dense-, gap-, and open-graded mixes; however, the seal must penetrate.

10. What is a Rejuvenating Seal? A combination of various chemicals or a mixture of asphalt emulsion and recycling agents applied to the asphalt pavement surface. The primary purpose is to soften the stiffness of the oxidized AC pavement surface and to extend the life of the pavement surface by adjusting properties of the AC mixture.

11. Why Use a Rejuvenating Seal? • A way to soften the hardness of oxidized asphalt concrete surface, making it less brittle. • The major benefit of the rejuvenating seals is to improve the flexibility of the asphalt binder and slow down the rate of aging and oxidization.

12. When to Use a Rejuvenating Seal? • Old and fairly oxidized pavement surface or surface starting to oxidize or show raveling. • In addition to oxidation a pavement surface may begin to show evidence of distress cracking; if this is the case a rejuvenating scrub seal should be used. • Generally used on pavement over 2 years or more.

13. Heavily aged, dense-graded HMA Open-graded HMA Where to Use Rejuvenating Seal? • Can be used on dense-, gap- and open-graded pavement surface mixes

14. Module 7-1 Design, Materials & Specifications From… Maintenance Technical Advisory Guide (MTAG)

15. Project Selection – Fog Seals • Pavement surface condition – Dry mixes, high air voids, and surfaces showing minor and/or moderate raveling. Fog seal can also be used on chip seals to prevent aggregate loss. • Pavement age – relatively newer pavement (not more than 2 years in service) • Pavement surface mix – can be used on dense-, gap-, and open-graded mixes; however, the seal must penetrate.

16. Heavily aged, dense-graded HMA Open-graded HMA Fog Seals - Suitable Surfaces

17. Fog Seals - Unsuitable Surface Dense-graded HMA with closed surface

18. Fog Seals - Before and After Fog seal over existing chip seal

19. Project Selection – Rejuvenating Seals • Pavement surface condition – old and fairly oxidized surface or surface starting to oxidize or show raveling. In addition to oxidation a pavement surface may begin to show evidence of distress cracking; if this is the case a rejuvenating scrub seal should be used. • Pavement age – generally used on pavement over 2 years or more. • Pavement surface mix – Can be used on dense-, gap- and open-graded mixes

20. Design Considerations • The design objective is to determine the application rate and sometimes dilution rate. The actual application rates may vary during the construction.

21. Materials - What is an emulsion? • Mixture of asphalt binder, water, and emulsifying agent • 50 to 75% of mix is asphalt • “Breaking”—separation of water and asphalt • “Curing”—development of asphalt mechanical properties

22. Materials – General Terminology • Original emulsion – A mixture of asphalt cement and water that contains a small amount of emulsifying agent. Original slow-setting grade emulsions contain up to 43 percent water and original rapid setting grade • Diluted emulsion – An original emulsion that has been diluted by adding an amount of water equal to or more than the total volume of original emulsions contain up to 45 percent water. • Residual asphalt content – The amount of asphalt remaining on the pavement surface after the emulsion has broken and cured (after all water has evaporated).

23. Materials – Fog Seals • Usually asphalt emulsion and water. In some cases, the emulsions are made with a range of additives for special purposes. • Emulsion types - may be • Cationic (i.e., a positive surface charge on the asphalt particles), or • Anionic (i.e., a negative surface charge on the asphalt particles). • Primary types used: CSS-1h and SS-1h. In some circumstances, CQS-1h (and LMCQS-1h) will give a faster set.

24. Emulsion - Classification

25. cationic rapid-setting high viscosity (65% asphalt) slow-setting cationic hard asphalt 57% asphalt high-float with solvent medium-setting(anionic) 65% asphalt EmulsionClassification Names CRS - 2 CSS - 1h HFMS - 2s

26. Materials – Rejuvenating Seals • They may be emulsions of rejuvenating additives and may include asphalt, polymers, and other additives • Types of products commonly used in California • Reclamite • Emulsified Recycling Agent (ERA ) • Topein C • Styraflex • PASS

27. Materials – Rejuvenating Seals • Reclamite - Emulsified recycling agent using heavy oils • ERA - Emulsified recycling agent combined with a softer asphalt • Topein C - Mixture of tall oil pitch, asphaltene resin, and petroleum asphalt emulsified with water • Styraflex - Mixture of recycling agent, polymer and emulsified asphalt • PASS - Mixture of recycling agent, polymer and emulsified asphalt

28. Specifications • Fog Seals - NSSP 37-050 • Rejuvenating Seals - NSSP 37-600

29. Module 7-2 Construction and Inspection From… Maintenance Technical Advisory Guide (MTAG)

30. Fog Seal Construction • Confirmation of Site Conditions • Surface preparation • Material preparation • Emulsion application • Sand blotter and sweeping (if necessary)

31. Confirmation of Site Conditions • Consideration of site conditions is essential to proper curing • Little or no chance of rain • Temperature conditions • Air: 5 °C (40 °F) • Pavement: 15 °C (60 °F) • Traffic control

32. Pavement Surface Preparation

33. Equipment Inspection • Broom • Spray distributor • Sand spreader • Trucks • All equipment

34. Materials Preparation • Slow setting emulsion recommended • Check compatibility of water used to dilute the emulsion • Dilute emulsion no more than 24 hours before application

35. Emulsion Application

36. Emulsion Application—Distributor Calibration • Pre-construction • Pump rate • Application rate • Coverage test

37. Emulsion Application • Application rate: 0.45 to 0.70 l/m2 (0.10 to 0.15 gal/yd2) • Spray temperature range: 20 to 70 °C (70 to 160 °F)

38. Emulsion Application (gal/yd2)

39. h h h Double Overlap Triple Overlap Roadway Surface Roadway Surface Asphalt Distributor—Spray Bar Height Spray Bar and Nozzles Single Overlap Roadway Surface

40. 90o 45o 15o Travel Direction Lateral Coverage Asphalt Distributor—Spray Nozzles

41. Distributor Truck Applying a Seal

42. Post Treatment Procedures • Sand blotter and sweeping (if necessary) • Pavement should NOT be opened to traffic until adequate friction is restored

43. Rejuvenating Seal ConstructionRejuvenator Application

44. Rejuvenating Seal ConstructionApplication of Sand

45. Dos and Don’ts • Do check water compatibility before dilution • Do check dilution - has it been done, by whom, and when? • Do ensure that there is no contamination of the base emulsion by water, oils, or other liquids. • Do prevent contamination by other emulsions. • Do protect emulsions from freezing or localized boiling due to the application of direct heat. • Do heat emulsion gently and ensure heating coils are under the liquid level (max 122F (50C)). • Do load from the bottom of tankers or sprayers to avoid foaming. • Do check equipment and nozzles. • Do check application rates. • Do exercise proper traffic control. • Do ensure the know-how is available on the job. • Do add water to emulsion, not emulsion to water.

46. Dos and Don’ts • Don’t store diluted emulsion longer than 24 hours. • Don’t continuously stir or circulate emulsion. • Don’t apply emulsion if air temperature is < 50°F (10C) and pavement temperature < 60°F (15C). • Don’t apply emulsion if rain or cool temperatures are imminent. • Don’t continue application if adequate breaking period is not available. • Don’t open treated surface to traffic until coefficient of friction is at least 0.30 as determined by CT 342.

47. Identify Problem Determine Cause Identify Solution Troubleshooting - Approach

48. Troubleshooting Summary A=Anionic; C=Cationic

49. Common Problems and Related Solutions

50. TroubleshootingWhat is wrong here? Streaking