Presentation delivered at the CalAPA San Diego Technical Committee meeting May 28, 2014 by Kevin Donnelly, Director of Pavement Preservation, Western Emulsions. Topic: Chip Seal and Scrub Seal Best Practices.

1. KEVIN DONNELLY , APM
DIRECTOR OF PAVEMENT PRESERVATION
CalAPA Tech Group
San Diego, CA
May 28, 2014

2. What is Pavement Preservation?
• By applying a series of cost-
effective treatments over the life
of a pavement, agencies can
treat more lane miles, preserve
their system and increase
customer satisfaction.
• The cumulative effect of
systematic, successive
preservation treatments is to
postpone costly rehabilitation
and reconstruction.
Pavement Preservation is "a program employing a network level, long-term strategy that
enhances pavement performance by using an integrated, cost-effective set of practices
that extend pavement life, improve safety and meet motorist expectations."
Source: FHWA Pavement Preservation Expert Task Group

3. Developing A Healthy Transportation Network
Pavement
Management
Pavement
Preservation
Pavement
Recycling
Preservation of good roads
with low cost treatments
saves big money– cost
savings is then used to
repair poor roads.
Recycling with Engineered Emulsions
saves 30% to 50% the cost over traditional
methods allowing more roads to be
repaired with same to better performance
expectations over traditional approach
Roadway inventory,
condition assessment,
deterioration and work
history allows agencies to
track performance,
develop political support
of treatments and build
accurate models for
future planning.

4. Treatments
Rejuvenating Fog Seal
Slurry Seals / Micro Surfacing
Chip Seal / Scrub Seal
Cape Seals
Scrub Membrane Interlayer
Recycles (CIR / CCPR)
Recycles (FDR)
Pavement Preservation Toolbox
70-100
60-80
25-70
25-70
20-50
0-50
0-40
Sound structural section
Sound structural section
Sound structural section
Fairly sound structural section
Fairly sound structural section
Fairly sound structural section
Failed / Partially failed structural section
PCI Use on
3-5 yrs
5-7 yrs
5-10 yrs
7-12 yrs
10-15 yrs
15-20+ yrs
Life Extension

6. Chip Seals and Scrub Seals are placed as:
• A “wearing course” meaning vehicles drive directly upon it;
• Part of a “cape seal” meaning a chip seal is first placed,
then covered by slurry seal or microsurfacing;
• An “interlayer” meaning a layer between distressed
underlying asphalt pavement and a new asphalt or
rubberized asphalt surface.

7. What exactly is a scrub seal?
• A scrub seal is a more advanced and aggressive multi-purpose chip
seal. This rapid crack fill technique utilizes a specialized emulsion which
is a polymer modified rejuvenating emulsion (PMRE) as the chip binder
and rejuvenator in conjunction with a mechanized scrub broom that
forces the optimum amount of emulsion into the cracks. The emulsion is
not only highly polymerized which adds flexibility, toughness and
durability but contains a recycling agent that conditions the aged surface
while restoring the asphaltenes and maltenes balance.

8. Why Do Agencies
Scrub Seal?
• Cost effective surface treatment
• Eliminates the need to crack seal
-Less neighborhood disruption
• Protects underlying pavement
• Waterproofs the pavement surface
• Seals cracks and imperfections
• Provides a new wearing surface
• Restores surface friction
• Improves Aesthetics and lane
delineation
• Extends the service life

9. Mechanics

10. Some Common Types of Chip Seal Oils
CRS-2
CRS-2P
PMCRS-2H
HFRS-2
CHFRS-2
CHFRS-2P
PMRE
ARE
PASS CR
STYRAFLEX

11. TESTING OF EMULSIONS
Composition
• Particle Charge
• Density
• Distillation
Storage and Handling
• Storage Stability
• Sieve
• Saybolt Viscosity
Reactivity
• Demulsibility
Residue Tests
• Float Test
• Penetration
• Dynamic Shear
Rheometer

12. Benefits of Polymer Modified
Emulsions or PME
Improved adhesion
(less chip loss)
Improved resistance to
flow at high temps
Improved flexibility at
low temps
Longer service life

13. Chip seal failures usually occur in two forms: stripping (loss of cover stone) and bleeding (excess asphalt
on the road surface). Many in the industry believe chip seals fail because emulsion and aggregate are not
well suited to each other. Certain emulsions do work better with certain aggregates, but seldom - if ever -
is the degree of compatibility between any emulsion and aggregate so poor that the asphalt will not coat
the rocks. Most failures result from issues related to one of the following six aspects of chip seal
construction, listed here with easy solutions:
Aggregate and emulsion spread rates.
Spread rates must be tailored to each project.
Construction techniques.
Properly adjusted and maintained equipment, proper timing, and good teamwork ensure quality chip
seals.
Weather.
Hot, dry weather is best for proper emulsion setting and curing.
Surface preparation.
Repair and clean the road surface: fill potholes, level ruts, seal large cracks, repair broken edges, and
scarify and recompact or stabilize an aggregate base, if necessary. If you chip seal over any of these
problems, expect these problems to reappear in short time.
Traffic control.
Keep traffic under 25 mph until after the emulsion sets, the rolling has been done, and the first brooming is
completed.
Materials.
Aggregate should be clean and dry, otherwise the emulsion won't adhere.
Source http://www.techtransfer.berkeley.edu/newsletter/05-4/sixsteps.php

14. Chip Seals and Scrub Seals are excellent Stress
Absorbing Membrane Interlayer for subsequent
treatments
• Slurry Surfacing
• Micro-surfacing
• PME Chip Seals
• Thin Blanket HMA Overlays
• Warm Mix Asphalt Overlays
• Ultra-Thin Bonded Wearing Course

16. Think Remaining Service Life (RSL) when
selecting roads

17. Double Chip Seal
Red Rover Mine Road

18. Pre-Construction Discussion
Ordering Materials
Material requirements
§ Min-max application temps
Weather Limitations
Surface Preparation
Cure Times
Sweeping tips techniques
Broom set up
Broom maintenance
Attaching to distributor
Adjustments to broom
Amount of material to carry in the
broom
How to work start/stops
Bridges
Joining passes

19. Pre-Construction Discussion
Striping tips
Aggregate application
construction sequence
§ How far between roller/spreader
Spray bar issues
Traffic control
Speed and weight effects on broom
Rolling techniques

20. Equipment Needed to Perform a Chip Seal
Asphalt Distributor Truck
Aggregate Distributor
Dump Trucks
Pneumatic Tire Rollers
Brooms
Tabs
Traffic Controls

21. Caltrans District 8 Maintenance
Hwy 74

24. PASS CR 5/16” Scrub Cape Seal w/ Type II Slurry

25. Micro Mill, 5/16” RAP Scrub Seal
with Type II RAP Micro Surfacing
Escondido Canyon Road - Acton, CA

26. Micro Surfacing on Scrub Seal
Stunt Road

27. Recycled Asphalt Pavement (RAP) Chip
• Cost effective with
best quality
• Produce multiple
products if possible
• Single stones and
conglomerations
• Residual asphalt
content will vary by
sample

28. Crushed and screened 5/16” Rap
aggregate

29. Thank you.
Kevin Donnelly, APM
Director, Pavement Preservation
kevin@westernemulsions.com
805-886-0900