fog seals, sand seals, scrub seals, and rejuvenators
TRANSCRIPT
Fog Seals, Sand Seals, Scrub Seals, and Rejuvenators
Learning Outcomes
1. List benefits of fog seals, scrub seals, sand seals, and rejuvenators
2. Describe recommended materials
3. Describe recommended construction procedures
4. List key quality control activities
Learning Outcomes (cont.)
5. Describe potential construction and performance problems
6. Identify troubleshooting solutions
Description
Spray application of asphalt emulsionTreatment differences
– Emulsion type– Use of aggregate – Method of embedment
Application rate, timing, and construction quality are critical
Benefits
Slowed aging processWaterproofed surfacePrevention of stone lossIncreased surface frictionBetter surface appearance
[Nitrogen Bases]
[Paraffins]
Asphalt Components
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
EmulsionIngredients
Asphalt– Slow setting: up to 43% water– Rapid setting: up to 35% water
Water: Impurities can be harmfulEmulsifying agent (surfactant)
EmulsionClassification
Electrical chargeSpeed of break: slow (SS), medium
(MS), and rapid set (RS)Asphalt relative viscosity: hard (h) or
soft (s)Polymer-modified asphalt (P or L)
CRS - 2
cationic
CSS - 1h hard asphalt
HFMS - 2s
65% asphalt
with solvent
EmulsionClassification Names
cationic
high-float
medium-setting(anionic)
slow-setting
rapid-setting
high viscosity(65% asphalt)
57% asphalt
EmulsionType
SlowSetting
MediumSetting
RapidSetting
Anionic SS-1SS-1h
MS-1MS-2MS-2h
HFMS-1HFMS-2
HFMS-2hHFMS-2s
RS-1RS-2
HFRS-2
Cationic CSS-1CSS-1h
CMS-2CMS-2h
CRS-1CRS-2
EmulsionClassification
EmulsionDistribution of Asphalt Particles
0.0037 mm (0.000145 in)
EmulsionTerminology
Original emulsion—asphalt, water, and emulsifying agent
Diluted emulsion—original emulsion diluted by additional water
Residual asphalt content—amount of asphalt left after water has evaporated
Aggregate
Applied to sand and scrub sealsClean material, smaller than 2 mm
(0.08 in)
Fog Seals
Fog SealsDescription
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
Fog SealsApplication Considerations
Seal must penetrate surface voidsEnvironment affects both break
and future performanceAllowing traffic before break is
hazardous!
Fog SealsSuitable Surfaces
Heavily aged, dense-graded HMA
Open-graded HMA
Dense-graded HMAwith closed surfaceDense-graded HMAwith closed surface
Fog SealsUnsuitable Surface
Fog SealsBefore and After
Fog seal over existing chip seal
Fog Seal Construction
1. Surface preparation
2. Material preparation
3. Emulsion application
4. Sand blotter and sweeping (if necessary)
Fog Seal ConstructionConfirmation of Site Conditions
Consideration of site conditions is essential to proper curing
Little or no chance of rainTemperature conditions
– Air: 5 °C (40 °F)– Pavement: 15 °C (60 °F)
Fog Seal ConstructionPavement Surface Preparation
Fog Seal ConstructionMaterials Preparation
Slow setting emulsion recommended
Check compatibility of water used to dilute the emulsion
Dilute emulsion no more than 24 hours before application
Fog Seal ConstructionEmulsion Application
Fog Seal ConstructionEmulsion Application—Distributor Calibration
Pre-constructionPump rateApplication rateCoverage test
Fog Seal ConstructionEmulsion 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)
Spray Bar and Nozzles
Single Overlap
Fog Seal ConstructionAsphalt Distributor—Spray Bar Height
hh
Roadway SurfaceDouble Overlap
Roadway SurfaceTriple Overlap
Roadway Surface
h
15o 45o 90o
TravelDirection
Lateral Coverage
Fog Seal ConstructionAsphalt Distributor—Spray Nozzles
Fog Seal ConstructionPost Treatment Procedures
Sand blotter and sweeping (if necessary)
Pavement should NOT be opened to traffic until adequate friction is restored
Sand SealsDescription
Spray emulsion followed by a light covering of sand
Improves friction“Locks” a chip sealCost: 0.40 to 0.80 $/m2
(0.33 to 0.66 $/yd2)Typical treatment life: 3 to 6 years
Sand SealsApplication Considerations
Low-speed, lower volume roadsTypically 2 to 5 mm (0.1 to 0.2 in)
thickNot as good a delineator as fog
seal
Sand Seal Construction
1. Surface preparation
2. Material preparation
3. Emulsion application
4. Sand application
5. Rolling
Sand Seal ConstructionEmulsion Application
Rapid setting typical, no dilutionApplication rate: 0.70 to 1.25 l/m2
(0.15 to 0.28 gal/yd2)Spray temperature range:
RS-1 20 to 60 °C (70 to 140 °F)
MS-1, HFMS-1 20 to 70 °C (70 to 160 °F)
RS-2, HFRS-2,
CRS-1, CRS-2
50 to 85 °C (125 to 185 °F)
Sand Seal ConstructionApplication of Sand
Clean, typically < 2 mm (0.08 in)Application rate: 5.5 to 12 kg/m2
(10 to 22 lb/yd2)Surface temperature: >15 °C (60 °F)Sand applied with a spreader
immediately after spray emulsion
Sand Seal ConstructionPost Treatment Procedures
Embedment with pneumatic-tired rollers
Open to traffic: ~ 2 hours
Scrub Seals
Scrub SealsDescription
Spray applied emulsion, drag-broomed, lightly sanded, drag-broomed again, and rolled
Fills surface voids and cracksCost: 0.60 to 1.00 $/m2
(0.50 to 0.83 $/yd2)Typical treatment life: 3 to 6 years
Scrub SealsApplication Considerations
Low to moderate volume roadwaysBrushing works emulsion into
pavement surfaceCan be applied in multiple layersThickness from 10 to 40 mm
(0.4 to 1.5 in)
Scrub Seal Construction
1. Surface and material preparation
2. Emulsion application
3. Initial drag-brooming of surface
4. Sand application
5. Second drag-brooming of surface
6. Rolling
Scrub Seal ConstructionEmulsion Application
Polymer-modified emulsionApplication rate: 0.63 to 0.82 l/m2
(0.14 to 0.18 gal/yd2)Emulsion temperature: 44 to 71°C
(110 to 160 °F)Pavement temperature: 21 to 32 °C
(70 to 90 °F)
Scrub Seal ConstructionInitial Drag-Brooming of Surface
Scrub Seal ConstructionSand Application
Application rate: 6.5 to 8.1 kg/m2 (12 to 15 lb/yd2)
Minimum of two roller passes
Scrub Seal ConstructionSecond Drag-Brooming and Rolling
Rejuvenators
Emulsions that include asphalt, polymer latex, and other additives
Softens existing binderTrade names:
– Reclamite– PASS– Topien C
Rejuvenator Application
Rejuvenator ApplicationApplication of Sand
Fog Seals, Sand Seals, Scrub Seals, and Rejuvenators
QUESTIONS?