Chapter 6 Chip 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/m 2 to $1.32/m 2 ($0.80 to $1.10/yd 2 )

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 SEALS

Sweeping (before and after) Rolling Aggregate Application Binder Application

Proper Application

Loose Chips BleedingStreaking

Chip Seal Variations Single chip seals Double or triple chip seals Cape Seals Sand seals Fabric and chip seals

Chip Seal Variations Single Chip Seals Existing Pavement Pneumatic- Tired Roller Binder

Chip Seal Variations Double Chip Seals Existing Pavement Binder Pneumatic- Tired Roller Second Binder Application Pneumatic- Tired Roller

Chip Seal Variations Cape Seals Existing Pavement Pneumatic- Tired Roller Binder Slurry Seal Brooming

Chip Seal Variations Sand Seals Existing Pavement Pneumatic- Tired Roller Binder

Chip Seal Variations Fabric and Chip Seals Existing Pavement Tack Coat Paving Fabric Binder Application Pneumatic- Tired Roller

Chip Seal Variations Fabric and Chip Seals

Chip Seal Course Training 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 Considerations Quantity 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)

Workshop Chip Seal Design Problem Break into groups Work design problem in Participant’s Workbook Present findings to class

Material Selection Binder

Material Selection Binder Rapid setting emulsions Polymer-modified emulsions Asphalt cement Rubberized asphalt

Asphalt Water Emulsifying agent (surfactant) Material Selection Emulsion Ingredients

Material Selection Emulsion 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)

Emulsion Type Slow Setting Medium Setting Rapid Setting AnionicSS-1 SS-1h MS-1 MS-2 MS-2h HFMS-1 HFMS-2 HFMS-2h HFMS-2s RS-1 RS-2 HFRS-2 CationicCSS-1 CSS-1h CMS-2 CMS-2h CRS-1 CRS-2 Material Selection Emulsion Classification

Material Selection Rubberized Asphalt Chip Seal

Binder Material Field 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 Chip  Chips are always hot pre-coated, and applied at lbs. per square yard Hot Rubber Chip Seals

Asphalt Rubber Chip Seal

Binder Terminal Blended using hot asphalt, polymer and can use crumb rubber.  Application rate is gals/sy depending on size of chip Chips  Chips 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

Polymer Modified Emulsion Chip Seals Crack Seal before PM Emulsion Seal

Binder Polymer modified emulsion with a solvent free rejuvenating agent additive  Application rate is gals/sy depending on size of chip and degree of cracking. Chips  Chips can be 1/4” up to 1/2” (18-35 lbs. / sy)  Can be applied at temperatures down to 40 o F  Crack filling is not required PM Emulsion Rejuvenating Chip Seals

Material Selection Aggregates 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 Pneumatic- Tired Roller Binder Material Selection Problem 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

Construction

Construction Conventional Chip Seal Procedure 1. Clean existing pavement 2. Apply binder 3. Spread aggregate 4. Roll 5. Allow binder to cure 6. Broom loose aggregate

Construction Cleaning Existing Pavement

Construction Start and Stop Application on Mat

Construction Binder Application

Spray Bar and Nozzles Single Overlap Construction Binder Overlap h h Roadway Surface Double Overlap Roadway Surface Triple Overlap Roadway Surface h

Construction Binder Application Overlap Triple Overlap

Construction Binder Application

Construction Aggregate Application

Immediate rolling of aggregate Pneumatic-tired rollers No fewer than three passes Full coverage necessary before asphalt hardening Construction Rolling

Time depends on temperature and relative humidity Emulsion break should begin just after first roller pass Open to traffic in about 2 hours Construction Curing of Binder

Construction Brooming Loose Aggregate

Project review Document review Material checks Quality Control Preliminary Responsibilities

Surface preparation Equipment inspection Asphalt distributor Chip spreader Haul trucks Rollers Brooms Quality Control Pre-Application Inspection

Weather requirements Determining application rates Checking application rates Traffic control plan and setup Quality Control Pre-Application Inspection (continued)

Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming Quality Control Project Inspection

Cleanup Opening to traffic Quality Control Post-Application Inspection

Project review Document review Material checks Quality Control Preliminary Responsibilities

Surface preparation Equipment inspection Asphalt distributor Chip spreader Haul trucks Rollers Brooms Quality Control Pre-Application Inspection

Weather requirements Determining application rates Checking application rates Traffic control plan and setup Quality Control Pre-Application Inspection (continued)

Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming Quality Control Project Inspection

Cleanup Opening to traffic Quality Control Post-Application Inspection

Project review Document review Material checks Quality Control Preliminary Responsibilities

Surface preparation Equipment inspection Asphalt distributor Chip spreader Haul trucks Rollers Brooms Quality Control Pre-Application Inspection

Weather requirements Determining application rates Checking application rates Traffic control plan and setup Quality Control Pre-Application Inspection (continued)

Asphalt application Aggregate application Truck operation Rolling Longitudinal joints Transverse joints Brooming Quality Control Project Inspection

Cleanup Opening to traffic Quality Control Post-Application Inspection

Troubleshooting

Troubleshooting What is wrong here? Streaking

Troubleshooting What is wrong here? Poor Longitudinal Joint

Troubleshooting What is wrong here? Bleeding

Troubleshooting What is wrong here? Loss of Cover Aggregate

Troubleshooting What is wrong here? Inadequate Aggregate Coverage

Problem: Troubleshooting Possible Construction Problems Aggregate embedment > 80 percent Potential causes?

Problem: Troubleshooting Possible Construction Problems Aggregate embedment < 50 percent Potential causes?

Troubleshooting What is wrong here? Loss of aggregate due to inadequate curing

Troubleshooting What is wrong here? Single Overlap

Troubleshooting What happened here?

Questions?