Selecting the Right Maintenance Treatment

Sponsored by: Minnesota LTAP Center

Presented by: Michael Marti, P.E.SRF Consulting Group, Inc.

Dan Wegman, P.E.SemMaterials

For Each Maintenance TreatmentAn agency needs to define:

• Description/Purpose• Timing• Effects on various pavement distress• Anticipated performance/service life• Unit cost• Roadway use/level of traffic• Traffic control concerns• Limitations

– Seasonal– Availability of qualified staff and contractors– Availability of quality materials

• Construction specifications

MaterialMn/DOT

Spec. Recommended ApplicationFog Seal 2355 CSS-1 or CSS-1h diluted with 50% water usually

applied at 0.05 to 0.15 gal/sy, depending on thepavement texture, weather conditions and traffic. Aspraying temperature of 125 to 160o F and surfacetemperature of at least 50o F is recommended.

Seal Coat 2356 See the Seal Coat Handbook (Mn/DOT documentnumber 1999-07) for design methodology andapplication rates.

Chip seals should not be placed in cool weather or ondays with high humidity. They should also not beplaced when there is a chance of rain.

DoubleChip Seal

None Use the design application rates.Pavement should be dry and clean, and all necessaryrepairs or reconditioning work should be completedprior to placement of the double chip seal.

Recommended Applications Surface Treatments

Material

Mn/DOT Spec.

Recommended Application

Slurry Seal None Pavement should be dry and clean, and all necessary repairs or reconditioning work should be completed prior to placement of the slurry seal. Pace when the air and pavement temperature are both at least 50o F and there is no chance of freezing within 24 hours after placement. Do not place during rain.

Micro-surfacing

Special Provision

Mix design must be followed carefully. Ideal for high volume roads. Pavement should be clean, and all necessary repairs or reconditioning work completed prior to placement of the micro-surfacing.

Thin Overlay

2350 LV Type 5

It is important to use a quality mix. Density is vital to performance. Sand mixes (aggregate size 3/8” minus) are not recommended. Place with paver, not blade.

Recommended Applications Surface Treatments

Material

Mn/DOT Spec.

Recommended Application

Cold mix 2381 Cold mix is normally used during winter months. Important to use high quality material and to compact properly. Emulsions are recommended for safety and environmental reasons.

Spray Injection

None This process is best suited for transverse crack repair and pothole filling. Fairly high production, but operator dependent. A primary cause of poor patch life is insufficient density. Since asphalt emulsion is compatible with water, the crack needs not be perfectly dry to obtain long patch life.

Hot Mix 2350 LV type 5

Clean reservoir. Use in good weather. Compaction is essential for every patch, even if it is accomplished by driving over the patch with a truck. Material should be placed in the patch area, not thrown in.

Slurry and Micro-surfacing material

None Based on availability of equipment to be used for transverse crack leveling. This process is a high-production operation that should create a level surface. Micro-surfacing gives a more durable patch, but is more sensitive to placement activities. Because of the required cure period, slurry should not be used to fill deep cracks or cracks that have developed large potholes.

Recommended ApplicationsPatching

Asphalt Maintenance Techniques

Equivalent Annual Cost (EAC) = Unit Cost/Years of Life

Treatment Unit CostApproximate Life (Years) EAC

Crack Sealing $1.00 / lf 2 – 3 $0.40

Fog Seal $0.20/yd2 3 – 4 $0.04

Chip Seal $0.55/yd2 3 – 6 $0.12

Slurry Seal $1.50/yd2 3 – 5 $0.38

Micro-surfacing $1.75/yd2 5 – 8 $0.27

Ultra Thin Bonded Overlay

$2.90/yd2 8 – 10 $0.32

Thin Overlay $3.00/yd2 2 – 10 $0.43

• Existing pavement – Type, structure, roughness, skid, distresses, climate, etc.

• Environment– Climate, past & future traffic, noise, etc.

• Life cycle costs– Construction, maintenance, rehabilitation, user-delay

costs, impact on local businesses, vehicle repair, etc.

• Available treatments– Construction requirements, performance, costs,

capabilities of local contractors

Right Treatment Depends on

Analysis Procedures for Most Effective Treatment

• A number of procedures for determining cost effectiveness exist and should be used

• Cost should be part of the decision process but not the only consideration

• Use of decision trees is a viable method– Cost– Life Cycle– Pavement Management of Network– User Delay – Availability of Contractors– Availability of Materials

Right Treatment,Right Time,

Right ProjectDone Right!

Example of Selection Process

• Determine Rating Factors

• Assign “Importance Value” to Each Factor– Percentage (must total 100)

• Rank each of the Available/Applicable Maintenance Treatments

• Calculate Totals

Determine Rating Factors• Cost• How well it “fixes” distresses• Traffic Disruption (during maintenance)• Traffic Disruption (long term)

Assign “Importance Value” to Each Factor• Percentage (must total 100)

Rank each of the Available/Applicable Maintenance TreatmentsCalculate Totals

Determine Rating Factors• Cost• How well it “fixes” distresses• Traffic Disruption (during maintenance)• Traffic Disruption (long term)

Assign “Importance Value” to Each Factor• Percentage (must total 100)

Rank each of the Available/Applicable Maintenance Treatments

Example of Selection Process11-Year Old Pavement, 6000 ADT, Previously Seal Coated,

L-Block Cracking, L-Rutting, L-Polished

Determine Rating Factors• Cost• How well it “fixes” distresses• Traffic Disruption (during maintenance)• Traffic Disruption (long term)

Assign “Importance Value” to Each Factor• Percentage (must total 100)

Determine Rating Factors• Cost• How well it “fixes” distresses• Traffic Disruption (during maintenance)• Traffic Disruption (long term)

Definition of Pavement Preservation

The right treatment,

At the right time,

On the right project.