Transcript Asphalt Pavement Maintenance Handbook

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 Treatment
An agency needs to define:
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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
Recommended Applications
Surface Treatments
M aterial
Fog Seal
M n/DOT
Spec.
2355
Seal Coat
2356
Re commended Application
CSS-1 or CSS-1h diluted with50% water usually
applied at 0.05 to 0.15 gal/sy, depending on the
pavement texture, weather conditions and traffic. A
o
spraying temperature of 125 to 160 F and surface
temperature of at least 50o F is recommended.
See the Seal Coat Handbook (Mn/DOT document
number 1999-07) for design methodology and
application rates.
Chip seals should not be placed in cool we ather or on
days with high humidity. They should also not be
placed when the re is a chance of rain.
Double
Chip Seal
None
Use the design application rates.
Pavement should be dry and clean, and all necessary
repairs or reconditioning work should be completed
prior to placement of the double chip seal.
Recommended Applications
Surface Treatments
Material
Slurry Seal
Microsurfacing
Thin
Overlay
Mn/DOT
Spec.
None
Special
Provision
2350 LV
Type 5
Recommended Application
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
o
at least 50 F and there is no chance of freezing within
24 hours after placement. Do not place during rain.
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.
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
Patching
Material
Cold mix
Mn/DOT
Spec.
2381
Recommended Application
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
Microsurfacing
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.
Asphalt Maintenance Techniques
Reasons for Use
High
Average
Treatment
Life
Average
Unit
Cost
X
X
3
7-10
3
2-3
5
$0.20/lf
$1.70/lf
$0.70/lf
$0.25/lf
$5.00/lf
1-2
3-6
7-10
3-5
5-8
5-8
$0.15/sy
$0.55/sy
$1.50/sy
$1.50/sy
$1.75/sy
$35/ton
Crack Severity
Friction
Raveling Rutting Potholes
Low
Med
X
X
X
X
X
Crack treatments
Clean & seal
Saw & seal
Rout & seal
Crack filling
Full depth
Surface treatments
Fog seal
Seal coat
Double chip seal
Slurry seal
Micro surfacing
Thin overlay
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X
Equivalent Annual Cost
(EAC)
= Unit Cost/Years of Life
Unit Cost
Approximate
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
Treatment
Right Treatment Depends on
• 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
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
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Cost
Life Cycle
Pavement Management of Network Right Treatment,
User Delay
Right Time,
Availability of Contractors
Right Project
Availability of Materials
Done 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
Example of Selection Process
11-Year Old Pavement, 6000 ADT, Previously Seal Coated,
L-Block Cracking, L-Rutting, L-Polished
 Determine
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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
 Calculate Totals
Definition of Pavement Preservation
The right treatment,
At the right time,
On the right project.