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A County of Los Angeles Case Study

Fixing Faults With Limited Funds

Background

Office: 626-458-4923Cell: 626-476-7767idiaz@dpw.lacounty.gov

Imelda Diaz, P.E., M.S.

• Unit Head of the Pavement Management Unit in the Geotechnical & Materials Engineering Division of the County of Los Angeles Department of Public Works

• 18 years of service with the County of Los Angeles

• Manages largest & most complex county road network in the state

• B.S. & M.S. in Civil Engineering with an emphasis on materials & geotechnical engineering from California State University, Long Beach

• Served as technical advisor for the Southern California Rubberized Asphalt Concrete Technology Center

Background

Doug Ford

• A 21-year pavement preservation industry veteran

• President of Pavement Coatings Co.

• Active member of the California Chip Seal Association

• Current President of the International Slurry Surfacing Association (ISSA)

Office: 714-826-3011Cell: 714-713-7978dford@pavementcoatings.com

Background

ISSA• ISSA is an international non-profit

trade association that promotes pavement preservation– Slurry & Micro Surfacing– Chip Sealing– Crack Treatment

• ISSA educates & promotes the highest standards of ethics & quality

• Members include contractors, equipment manufacturers, public officials, research personnel, consulting engineers & other industry professionals

ISSA Pavement Condition Index shows how proper pavement preservation timing reduces overall pavement lifecycle costs

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• Project Scope

• Budget Limitations

• Project Execution

• Project Results

• Questions & Answers

Agenda

Project Scope

• 3.5 miles of roadway

• High volume, peak period connector between two major arterials

• 40 miles northwest of Los Angeles

• 12 miles from the San Gabriel Fault

• Geological activity have historically impacted the road

• Unsuitable subgrade material in several locations

• Project completed in 11 days

Vasquez Canyon Road

Project Scope

ChallengesLarge Cracks throughout resulting from geologic activity and/or unsuitable subgrade from fault line land movement

Project Scope

ChallengesLarge Cracks mean frequent patching and high maintenance needs

Project Scope

ChallengesFrequent patching yields uneven roadways and rough ride for commuters

Project Scope

Use the most cost-effective methods possible to eliminate ongoing high maintenance costs, improve the rideability of the road for commuters, and extend the life of the road by at least 5 years. until the county could redesign the geometrics of the road

Objective

Project Scope

Budget Limitations

• NEED INFORMATION HERE– Was this a planned and budgeted project?– How did you fit it into the budget it not planned?– How and Why did you choose the methods of Pavement Preservation you

did?– What was the actual budget and did the project end up under or over

budget?

Project Scope

Breakdown Of Processes Used

• Leveling of the most seveir areas was accomplished by milling of high areas and filling of low areas with Hot Mix Asphalt

• Project mainly consisted of cold-in-place recycling with a micro surfacing overlay

– Cold-In-Place-Recycling (CIR) 52,716 square yards

– Type II Micro Surfacing 52,716 sq.yds @ 18 lbs/sq.yd and 14% emulsion

• We also did a cement treated base as a test area

– Cement Treated Base (CTB) 4,500 square yards

Project Execution

1. Digouts and milling were performed to level the road (fill low spots or remove high spots)

2. Cement Treated Base Test Section: Removed 3” of AC from 1,350 lane feet & stockpile grindings on sitePulverized & cement treated with 5% cement to a depth of 12”Moved AC grindings back into place, grade & roll

3. Recycled to a depth of 3” using Cold-In Place Recycling Method

4. Fog sealed with a SS1h, lightly sanded & cured for 4 days

5. Applied Type II Micro Surfacing

Steps

* Test section where cement treated base was used

Project Execution

1. Step one was to return save ride to the areas affected by severe land movement

2. Where the Cement Treated Base would be utilized:

✔Removed 3” of AC from 1,350 lane feet & stockpile grindings on site

✔Pulverized & cement treated with 5% cement to a depth of 12”, graded and compacted

✔Moved AC grindings back into place, grade & roll

3. Recycled to a depth of 3” using Cold-In-Place Recycling Method

4. Fog sealed with a SS1h, lightly sanded & cured for 4 days

5. Applied Type II Micro Surfacing

Steps

Project Execution – Reusing The Puzzle Pieces

Leveling ProcessAreas of land movement had to be returned to a smooth and safe condition

• Extensive milling of high areas

• 200 tons of hot mix asphalt used to fill low and depressed areas

Project Execution – Reusing The Puzzle Pieces

Leveling ProcessAreas of land movement had to be returned to a smooth and safe condition

• Extensive milling of high areas

• 200 tons of hot mix asphalt used to fill low and depressed areas

Project Execution – Reusing The Puzzle Pieces

Cement Treated BaseTest Areas of CTB was completed at the beginning of the roadway

Heaviest traffic loads utilize this section of road

Project Execution – Reusing The Puzzle Pieces

Cold-In-Place RecyclingEnvironmentally & Budget Friendly

• Cost-efficient labor & transportation

• Uses existing materials & no heat

• Using existing materials = no need to purchase or transport fresh aggregate

• No heat = reduced noxious fume emissions

Project Execution – Reusing The Puzzle Pieces

Cold-In-Place RecyclingType I Cold-In-Place Recycling Process

1. Reclaim top 3-4 inches using milling machine

2. Crush reclaimed material & screen for proper sizing

3. Add reclaimed material to paver

4. Pave into place

5. Compact with steel drum & rubber tire pneumatic rollers

This process is completed with a combination of machinery referred to as a “train”

Project Execution – Reusing The Puzzle Pieces

Cold-In-Place Recycling

Paving Recycled asphalt with conventional equipment

The use of electronic “skies” improves the finished ride

Project Execution – Reusing The Puzzle Pieces

Cold-In-Place Recycling

Quality Control requires a field set rolling pattern

The pattern must be continually monitored for changes

Final re- roll will occur one to two days after placement, warm temperatures help obtain maximum densities

Project Execution – Filling The Voids

Fog Seal“A light spray application of dilute asphalt emulsion used primarily to seal an existing asphalt surface to reduce raveling and enrich dry, weathered surfaces”

Asphalt Emulsion Manufacturers Association

Project Execution – Icing On The Cake

Why Micro Surfacing?

• Improves skid resistance

• Extends service life by up to 7 years

• Quick-drying aspects shorten traffic delays–drivable after 1 hour

• Does not alter drainage/curb reveal

• Helps eliminate hydroplaning

• Cost-effective surfacing

• Rutting, shoving & cracking resistant

• Applied at ambient temperatures, which lowers energy requirements & eliminates pollutants

Project Execution – Icing On The Cake

Micro Surfacing

1. Begins as a mixture of dense-graded aggregate, asphalt emulsion, water & mineral fillers

2. Added capabilities from use of high-quality advanced polymers & other modern additives

3. Applied with special paver that carries all components , mixes them on-site & spreads to roadway

4. Mixture is continuously fed into a full-width spreader box

5. Spreads the width of a traffic lane in one pass

Surface is initially dark brown, but finishes black once water is chemically ejected & the surface cures

Project Results

• Existing asphalt reclaimed & repurposed

• Water & air permeability lowered

• Even driving surface with good traction created

• BUDGET STATEMENT TO BE ADDED

Questions & Answers

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Fixing Faults With Limited Funds

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