chapter 6 chip seals from… maintenance technical advisory guide (mtag)
TRANSCRIPT
Chapter 6Chip Seals
From… Maintenance Technical
Advisory Guide (MTAG)
Manager’s Overview
From… Maintenance Technical
Advisory Guide (MTAG)
Introduction to Chip Seal
What is Chip Seal?Why use Chip Seal?When to use Chip Seal? Where to use Chip Seal?Chip Seal Variations
What Is Chip Seal
Description
Application of asphalt binder on existing pavement followed by a layer of aggregate chips. The treatment is then rolled to embed the aggregate into the binder.
Performance and Cost-Why to Use
Performance• Proper application of binder and aggregate
• Proper embedment
• Typical treatment life: 4 to 7 years
Average cost• $0.96/m2 to $1.32/m2 ($0.80 to $1.10/yd2)
Surface for light to medium traffic Waterproof layer Skid resistant surface Restore weathered surface Address bleeding Temporary base course cover Define shoulders
Where and When to Use
When NOT to Use!
Structurally deficient pavements Cracks >6 mm (0.25 in) wide Medium- to high-severity alligator
cracking Large number of potholes Rutting >25 mm (1 in) Very rough surface
Keys for Success
Proper surface preparation Use the right emulsion and clean aggregates Determine the appropriate spread rates for the
emulsion and the aggregate Follow the construction specs, including the
need for traffic control Chip seal in good weather conditions
CHIP SEALSCHIP SEALS
Sweeping (before and after)Sweeping (before and after)
RollingRollingAggregate Aggregate ApplicationApplication
Binder Binder ApplicationApplication
Chip Seal Variations
Single chip seals Double or triple chip seals Cape Seals Sand seals Fabric and chip seals
Chip Seal VariationsSingle Chip Seals
Existing Pavement Binder
Chip Seal VariationsDouble Chip Seals
Existing Pavement Binder
Second BinderApplication
Chip Seal VariationsCape Seals
Existing Pavement Binder
Slurry Seal
Chip Seal VariationsSand Seals
Existing Pavement Binder
Chip Seal VariationsFabric and Chip Seals
Existing PavementTackCoat
Paving Fabric
BinderApplication
Chip Seal VariationsFabric and Chip Seals
Chip Seal CourseTraining Modules Available
1. Design, Materials & Specifications
2. Construction, QC & Trouble Shootings
End Overview
Begin Project Design, Materials & Specifications
Design, Materials & Specifications
From… Maintenance Technical
Advisory Guide (MTAG)
Module 6-1
Design, Materials & Specifications
22
Topics to be covered
Chip Seal Design Process Design Considerations -Quantity
Selection Chip Seal Design Methods Material Selection – Binder and
Aggregate
Chip Seal Design Process
Assess existing pavement Select chip seal variation Select compatible binder and aggregate Quantity selection
Design ConsiderationsQuantity Selection
Residual asphalt content• Asphalt cement factor = 1.0
• Emulsion factors range = 0.55 to 0.65
Aggregate application rate• Single chip layer
• No more than 10% excess chips
• 70% embedment recommended
Chip Seal Design Methods
McLeod procedure Asphalt Institute method
Asphalt Institute Method
1. Determine aggregate size and specific gravity
2. Aggregate and asphalt emulsion quantities from table
3. Adjust aggregate (if necessary)
4. Adjust asphalt content based on condition of road (if necessary)
WorkshopChip Seal Design Problem
Break into groups Work design problem in Participant’s
Workbook Present findings to class
Material SelectionBinder
2-4.28
Material SelectionBinder
Rapid setting emulsions Polymer-modified emulsions Asphalt cement Rubberized asphalt
Asphalt Water Emulsifying agent (surfactant)
Material SelectionEmulsion Ingredients
Material SelectionEmulsion Classification
Electrical charge (+ or –) Speed of break: slow (SS), medium (MS),
and rapid set (RS) Asphalt relative viscosity: hard (h) or soft
(s) Polymer-modified asphalt (P or L) High float (HF)
EmulsionType
SlowSetting
MediumSetting
RapidSetting
Anionic SS-1SS-1h
MS-1MS-2
MS-2hHFMS-1HFMS-2
HFMS-2hHFMS-2s
RS-1RS-2
HFRS-2
Cationic CSS-1CSS-1h
CMS-2CMS-2h
CRS-1CRS-2
Material SelectionEmulsion Classification
Material SelectionRubberized Asphalt Chip Seal
2-4.33
Binder MaterialField Blended using hot asphalt, extender oil and crumb rubber.
Oil application is usually .60 gal / square yard through an agitated distributor truck attached with a vapor recovery system.
Aggregate ChipChips are always hot pre-coated, and applied at 35-40 lbs. per square yard
Hot Rubber Chip Seals
Asphalt Rubber Chip Seal
BinderTerminal Blended using hot asphalt, polymer and can use crumb rubber.
Application rate is 0.35 - 0.50 gals/sy depending on size of chip
ChipsChips can be 3/8” up to 1/2” (25-35 lbs. / sy)
Chips can also be pre-coated but not required
Polymer Modified Chip Seals
PolymerModified EmulsionChip Seals
Crack Seal before PM Emulsion Seal
BinderPolymer modified emulsion with a solvent free rejuvenating agent additive
Application rate is 0.25 - 0.40 gals/sy depending on size of chip and degree of cracking.
ChipsChips can be 1/4” up to 1/2” (18-35 lbs. / sy)
Can be applied at temperatures down to 40o F
Crack filling is not required
PM Emulsion Rejuvenating Chip Seals
Material SelectionAggregates
Clean and durable One size: 6 to 16 mm (0.25 to 0.6 in) Cubical shape Flat and elongated particles limited to 25
to 30 percent Fines limited to 1 to 2 percent
Existing Pavement Binder
Material SelectionProblem With Flat Aggregates
Design, Materials & Specifications
43
End Project Design, Materials & Specifications
Begin Construction, QC, and Trouble Shooting
Construction and Inspection
From… Maintenance Technical
Advisory Guide (MTAG)
Module 6-2
Construction & Inspection 45
Construction Procedures
Quality Control
Inspection
Troubleshooting
Topics to be covered
ConstructionConventional Chip Seal Procedure
1. Clean existing pavement
2. Apply binder
3. Spread aggregate
4. Roll
5. Allow binder to cure
6. Broom loose aggregate
ConstructionCleaning Existing Pavement
ConstructionStart and Stop Application on Mat
ConstructionBinder Application
Spray Bar and Nozzles
Single Overlap
ConstructionBinder Overlap
hh
Roadway SurfaceDouble Overlap
Roadway SurfaceTriple Overlap
Roadway Surface
h
ConstructionBinder Application Overlap
Triple OverlapTriple Overlap
ConstructionBinder Application
ConstructionAggregate Application
ConstructionAggregate Application
Immediate rolling of aggregate Pneumatic-tired rollers No fewer than three passes Full coverage necessary before asphalt
hardening
ConstructionRolling
ConstructionRolling
ConstructionRolling
Time depends on temperature and relative humidity
Emulsion break should begin just after first roller pass
Open to traffic in about 2 hours
ConstructionCuring of Binder
ConstructionBrooming Loose Aggregate
Project review Document review Material checks
Quality ControlPreliminary Responsibilities
Surface preparation Equipment inspection
• Asphalt distributor
• Chip spreader
• Haul trucks
• Rollers
• Brooms
Quality ControlPre-Application Inspection
Weather requirements Determining application rates Checking application rates Traffic control plan and setup
Quality ControlPre-Application Inspection (continued)
Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming
Quality ControlProject Inspection
Cleanup Opening to traffic
Quality ControlPost-Application Inspection
Project review Document review Material checks
Quality ControlPreliminary Responsibilities
Surface preparation Equipment inspection
• Asphalt distributor
• Chip spreader
• Haul trucks
• Rollers
• Brooms
Quality ControlPre-Application Inspection
Weather requirements Determining application rates Checking application rates Traffic control plan and setup
Quality ControlPre-Application Inspection (continued)
Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming
Quality ControlProject Inspection
Cleanup Opening to traffic
Quality ControlPost-Application Inspection
Project review Document review Material checks
Quality ControlPreliminary Responsibilities
Surface preparation Equipment inspection
• Asphalt distributor
• Chip spreader
• Haul trucks
• Rollers
• Brooms
Quality ControlPre-Application Inspection
Weather requirements Determining application rates Checking application rates Traffic control plan and setup
Quality ControlPre-Application Inspection (continued)
Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming
Quality ControlProject Inspection
Cleanup Opening to traffic
Quality ControlPost-Application Inspection
TroubleshootingTroubleshooting
2-4.76
TroubleshootingWhat is wrong here?
StreakingStreaking
TroubleshootingWhat is wrong here?
Poor Longitudinal JointPoor Longitudinal Joint
TroubleshootingWhat is wrong here?
BleedingBleeding
TroubleshootingWhat is wrong here?
Loss of Cover AggregateLoss of Cover Aggregate
TroubleshootingWhat is wrong here?
Inadequate Aggregate CoverageInadequate Aggregate Coverage
Problem:
TroubleshootingPossible Construction Problems
Aggregate embedment > 80 percent
Potential causes?
Problem:
TroubleshootingPossible Construction Problems
Aggregate embedment < 50 percent
Potential causes?
TroubleshootingWhat is wrong here?
Loss of aggregate due to inadequate curingLoss of aggregate due to inadequate curing
TroubleshootingWhat is wrong here?
Single OverlapSingle Overlap
TroubleshootingWhat happened here?
Questions?