Spray Applied Polymer Surface Seals - TSP2

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Lessons Learned Fog Seal When to Use? Pavement Age • Seal newer pavements • Rejuvenate age-embrittled pavements Permeability Enables Infiltration • Mix design (coarse, fine, open, SMA) • Construction density • Densification under traffic When to Use Fog and Rejuvenator <strong>Seals</strong> One goal of the study is to determine the timing of sealing applications. The DOT survey showed that many agencies have a scheduled fog seal application program for preventive maintenance that begins between two and ten years after HMA construction, and some routinely use spray applied seals immediately after chip sealing. Observations of four-year old seals in this study showed that most materials exhibited minimal visible color difference between sealed and control sections because most asphalt residue had worn off of the surface aggregate. However, the water, raveling and cracking protection still appeared to be intact. While the most accurate approach would be a test parameter for determining when to reseal, the required testing is not practical for most agencies. Once aging models and product performance criteria are understood, it should not be difficult to establish timing models that require minimal testing for verification. A scheduled interval based on the climate, traffic and surface type of "every x years or observation of minor distress, whichever comes first" may be the best strategy. Possible triggers for sealing or resealing might include: very small surface cracks, permeability above a specified level, raveling, loss of fines or mastic from the surface, or rheological (DSR and/or BBR) tests indicating excessive age hardening. Older conventional wisdom suggests that surface pitting and raveling begins when binder ductility measured at 15ºC falls below 10 cm, and block cracking begins when the ductility reaches 5 cm. Even if a simple timing approach is adopted, pavement permeability will remain a critical variable. If emulsions do not infiltrate into the surface, friction may be a problem and performance will not be satisfactory, resulting in accidents and potential disuse of spray applied seals. Field or lab permeability tests, infiltration tests such at the ring test (12), pour tests, or short trial sections on the pavement may be used. A more aggressive alternative might be a performance test for friction upon release to traffic or following a prescribed curing period, preferably based on a pre-project test strip. Caltrans recently funded research to be led by Dr. Gary Hicks at the regional Pavement Preservation Technical Center at Chico State which will deliver a performance specification for fog seals, including friction requirements. 54
Lessons Learned Fog Seal How to Use? Emulsion grade and application rates vary with pavement surface type! Dense HMA OGFC or Asphalt-Rubber Chip Seal Emulsified sealers and rejuvenators are best used as preventive maintenance treatments on pavements in good condition, but with surfaces that have begun the aging process. They can be used on any asphalt pavement that has sufficient permeability to allow emulsion infiltration, but traffic should be controlled until the seals have fully cured and friction numbers are restored to acceptable levels. Sanding generally improves early friction, as long as loose sand is removed before full speed traffic is restored. Fog seals should not be used when a pavement has poor surface texture, large cracks, rutting, shoving, structural deficiencies or low friction numbers. The Minnesota SR251 project included crack sealing of thermal cracks a few months after the fog seal had been applied. When applied at the right time, the emulsified seals generally exhibited fewer new cracks than control sections. 55
Page 1 and 2:
Foundation for Pavement Preservatio
Page 3 and 4: Research Participants Acknowledgeme
Page 5 and 6: An Effective Preservation Program
Page 7 and 8: Fog Seal AEMA Definition: a light
Page 9 and 10: CALTRANS MTAG: Rejuvenating Fog Sea
Page 11 and 12: What do we know about Fog Seals? L
Page 13 and 14: Spray Applied Surface Seal : The Pr
Page 15 and 16: DOT Survey Why Fog Seal? Constructi
Page 17 and 18: DOT Survey Pavement Age When Fog Se
Page 19 and 20: Upper Midwest Experiences Nebraska
Page 21 and 22: Unsealed Shoulders 21
Page 23 and 24: MN shoulders: Shedding Light Rain 2
Page 25 and 26: MNDOT - Fog Sealing Chip Seals Ligh
Page 27 and 28: Fog Seals Reduce Snowplow Damage
Page 29 and 30: Fog Seals can reduce: •Moisture I
Page 31 and 32: Lessons Learned Why Fog? Improve Ag
Page 33 and 34: Lessons Learned Why Fog? Prevent Da
Page 35 and 36: Asphalt Oxidation Chemistry The Pro
Page 37 and 38: Asphalt Oxidation Chemistry The Mec
Page 39 and 40: Asphalt Durability Predicting Block
Page 41 and 42: ARIZONA VALIDATION SITE Constructed
Page 43 and 44: EFFECT OF PAVEMENT DEPTH ON AGED AS
Page 45 and 46: Increasing m-control with aging for
Page 47 and 48: Lessons Learned Fog Seal Product Se
Page 49 and 50: Test Section Locations AZ - US 87,
Page 51 and 52: Lessons Learned Fog Seal Where to U
Page 53: Lessons Learned Fog Seal Where NOT
Page 57 and 58: Lessons Learned Fog Seal Emulsion P
Page 59 and 60: Lessons Learned Fog Seal over Chip
Page 61: Lessons Learned How to Apply Seals
Page 64 and 65: Lessons Learned How to Apply Seals
Page 66 and 67: Lessons Learned Controlling Frictio
Page 68 and 69: Lessons Learned IFI (International
Page 70 and 71: Lessons Learned Pavement Permeabili
Page 72 and 73: Lessons Learned Fog Seal Emulsion I
Page 74 and 75: Lessons Learned Fog Seal Pavement F
Page 76 and 77: Lessons Learned Comparison of Frict
Page 78 and 79: Lessons Learned Fog Seal Binder Pro
Page 80 and 81: Rheology Testing of Field Samples G
Page 82 and 83: Permeabilities - MN 251 & OCR 112 1
Page 84 and 85: Permeabilities for AZ & CA 1 All da
Page 86 and 87: G*, Pa, 10 radians/sec, 64C Core Sl
Page 88 and 89: Fog Seal Low Temperature Mix Stiffn
Page 90 and 91: Lessons Learned Static Bending Test
Page 92 and 93: Asphalt Emulsion • Emulsion = A n
Page 94 and 95: Lessons Learned Fog Seal Emulsion P
Page 96 and 97: Field Observations Notes & photos
Page 98 and 99: Summary Findings Seals are particu
Page 100 and 101: Need for Improved Specifications fo
Page 102 and 103: Recommendations for Future Study N
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Spray Applied Polymer Surface Seals - TSP2

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