session 4 - long life pavement and preservation.pdf

8/17/2019 Session 4 - Long Life Pavement and Preservation.pdf

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Long Life Pavement and

Pavement Preservation

Session 4


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Part 1

The Pros and Cons ofPreventive Maintenance


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Part 1 Topics

Formal definitions

Benefits of preventive maintenance

Preventive maintenance programchallenges


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2-4

Formal Definitions

Maintenance

Preventive maintenance

Rehabilitation

Pavement preservation

Pavement management

Reconstruction


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2-5

Definitions Applied

P

a v e m e n t

C

o n d i t i o n

Time

PreventiveMaintenance

Reconstruction

Good

Poor

Rehabilitation

Routine/Corrective Maintenance

Pavement

Preservation


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Benefits of Pavement

Preservation

Improved Customer Satisfaction

Keeps them (and you) happy

Lowers User and Agency Costs inthe Long-Term

Saves them (and you) money.

Improved Safety Keeps them (and you) safer


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Benefits of Pavement

Preservation

Manage Assets

Protect investment

Enhance cost-effectiveness of treatments

Preventive Maintenance (PM)

Extend Pavement Life

Retard future deterioration Enhance Pavement Performance

Improve functional condition (friction, etc.)

Reduce User Delays


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The Essence of Pavement

Preservation

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The Essence of Pavement

Preservation

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Effective Preventive

Maintenance

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Examples

Michigan DOT -

“For every preventive maintenance $1 spent,we’re saving $10”

Rhode Island -

“I-295 will cost $30 million to fix; costs forpreventive maintenance would have been $6-

7 million over the years”

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The Life of a Pavement

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Pavement Maintenance

Preventive (Proactive)

Arrest light deterioration

Retard progressive failures

Reduce need for corrective maintenance

“Right” treatment at the “right” time!

Corrective (Reactive)

After deficiency occurs

More expensive

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When do we have to fix our

pavement


preserves good condition pavement

Corrective maintenance when the pavement loses:

Load carrying ability (excessive deflection)

Waterproofing (cracks)

Surface slope (rutting)

Surface roughness (too slick)

Ride quality (bumps)2-15


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Strategy to minimize costs

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Quality of road system with

time

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What’s the “Right” project

Start by looking at overal l road

network . . .

Keep pavement cond i tion such

that corrective maintenance isn’tneeded

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The Problem

Publ ic percept ion

“ f ix ing good roads” and not “fixing bad

roads”

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What is the “Right” treatment

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Right treatment depends on

Existing pavement

Environment

Life Cycle Costs Available Treatments

Customers’ Needs

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Existing pavement

type

structure

roughness, rideability

surface texture

distresses

drainage

etc.

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Right treatment depends on Environment

climate

past & future traffic

etc.

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Life Cycle Costs

construction

maintenance

rehabilitation

user-delay costs

impact on local businesses

vehicle repair

Etc.

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Right treatment depends on Available Treatments

Constructionrequirements

Performance Costs

Capabilities of localagencies and

contractors Etc.

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When should treatments be

applied

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Part 2

How PavementsPerform

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Part 2 Topics

Pavement types

Introduction to pavement performance

Typical pavement deterioration

Attributes of a pavement in good condition

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Pavement Types

Rigid (Portland Cement Concrete or PCC)

Flexible (Hot-Mix Asphalt or HMA)

Composite

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Types of Rigid Pavements

Jointed plain concrete pavement (JPCP)

Jointed reinforced concrete pavement(JRCP)

Continuously reinforced concretepavement (CRCP)

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JPCP

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Longitudinal Joints(with dowels or other)

Transverse Joints(with or without dowels)

PLAN

VIEW3.8 m to 7.6 m (typ.) (12.5 ft to 25 ft)


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JRCP

PLAN

VIEW7.6 m to 18.3 m (typ.) (25 ft to 60 ft)

Longitudinal Joint (withtiebars or other)

Transverse Joints(with dowels)

Deformed Welded WireFabric Reinforcing

(0.15% to 0.25%)

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CRCP

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Longitudinal Joint(with tiebars)

PLAN

VIEW

Typical Crack Spacing0.9 m to 2.4 m(3 ft to 8 ft)

ContinuousLongitudinal

Reinforcement(deformed bars)(0.6% to 0.8%)


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HMA

With unbound (granular) base

With bound (stabilized) base

Full-depth HMA

Composite HMA/PCC

Types of Hot-Mix Asphalt

(HMA) Pavements

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Surface Course

Intermediate Course

Base Course (Bound or Unbound)

Subbase Course (Usually Unbound)

HMA

Surface

Subgrade Soil

Asphalt Pavement

Terminology

Asphalt cement

Hot-mix asphalt (HMA)

Structure:

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T i l P


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Typical Pavement

Cross Section

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Role of Pavement Surface

Surface (PCC or HMA)

Base Course

Subbase Course

Subgrade Soil

4 Roles:

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Smooth ride

Skid resistance

Moisture barrier

Distribute load


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Load Distribution in

Rigid Pavements

3-38Subgrade soil

L d Di t ib ti i


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Load Distribution in

Flexible Pavements

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Sub rade soil


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Part 3

Long Life Pavement

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Definition

Pavement sections designed and built toperform as intended or longer withoutrequiring major structural rehabilitation or

reconstruction.

Only periodic surface renewal in responseto distresses confined to the top of the

pavement would be required.

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I t d ti t


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Introduction to

Pavement Performance

Measuring Performance

Factors affecting performance

Typical distresses

Deterioration mechanisms

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T M f P t


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Two Measures of Pavement

Performance

Functional performance:

present serviceability index, pavement surface

friction, and wet-weather safety index

Structural performance:

pavement structural capacity to accommodatefuture traffic

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Ch i i P


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Characterizing Pavement

Condition

Distress type, severity, and extent

Overall rating

Index or composite index

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Att ib t f P t i


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Attributes of a Pavement in

Good Condition

High level of service (LOS)

Safe

High customer satisfaction

Exceeds target performance indicators orhas limited deterioration; e.g.,

IRI < 1.5 mm/m (95 in/mi)

PCI > 70 or PCR ≥ 3.5

Skid Number > 353-45

F t Aff ti


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Factors Affecting

Pavement Performance

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Traffic

Subgrade

Soil

Materials

ConstructionVariability

Environment

Maintenanceand Rehabilitation

Design

T i l HMA


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Typical HMA

Pavement Distresses

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Fatigue cracking Bleeding

Block cracking Polishing

Edge cracking Roughness Longitudinal and transverse cracking

Reflection cracking

Raveling/weathering/oxidation Potholes

Rutting (stable/unstable)


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HMA Rehabilitation Strategies HMA over HMA renewal methods

HMA over existing HMA pavement HMA over reclaimed HMA (recycling)

HMA over PCC renewal methods HMA over existing HMA-surfaced composite

pavements HMA over crack and seated JPC pavements HMA over saw, crack and seat JRC pavements HMA over rubblized JPC pavements HMA over existing CRC pavements

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G idi P i i l t A hi


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Guiding Principles to Achieve

Long Life Pavement Keep the treatment solution as simple as

possible But not too simple so as to not address critical

underlying problems.

The quality of construction is essential inachieving long life pavements.

Pavements are supposed to act as one layer; Therefore the bond between layers should never

be compromised, and a few thick layers arealways better than multiple thin layers.

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Long Life Pavement All joints are weaknesses; therefore they need to

be treated as such. Good, continuous, and sustainable drainage is

essential to long life pavement; Therefore no matter how thick the renewal solution is,it can fail if drainage is not provided.

Foundation uniformity is essential toreduce/eliminate stress concentrations, which cancause future cracking.

A solid foundation allows good compaction;unsupported edges can never be properlycompacted.

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Long Life Pavement A solid foundation allows good compaction;

unsupported edges can never be properlycompacted.

Thermal movements of the existing pavementare the underlying cause for much reflectivecracking; therefore they must be eliminated(by fracturing the existing pavement).

Good performing asphalt mixtures should

have high binder content and low air voids (tohave high durability), and smaller nominalsize (to avoid segregation).

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Typical Rigid


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Typical Rigid

Pavement Distresses

Blow-ups

Transverse cracking

Longitudinal cracking Corner breaks

Materials-related

distress Transverse joint

faulting

Joint spalling

Joint seal damage

Loss of fines(pumping)

Polishing (loss offriction)

Map cracking andscaling

Roughness3-52


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Long Life Pavement

Foundation support (uniformity, volumetricstability [including stabilizing treatments])

Drainage design (moisture collection/removal

and design for minimal maintenance) Concrete mixture proportioning and

components (selected to minimize shrinkage

and potential for chemical attack, low CTE,provide adequate strength, etc.)

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G


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Long Life Pavement

Dowels and reinforcing (corrosionresistance, sized and located for goodload transfer)

Accuracy of design inputs Construction parameters (including paving

operations, surface texture, initial

smoothness, etc.) QA/QC (certification, pre-qualification,

inspection, etc.)

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Max Tensile Strain

Pavement Foundation

High ModulusRut Resistant Material (Varies As Needed)

Flexible Fatigue Resistant

Material 75 - 100 mm

40-75 mm SMA, OGFC or Superpave

}100 mmto150 mm

ZoneOf High

Compression

Perpetual Pavement


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Value

Quality . . . is what the customer gets out [of a

product] and is willing to pay for. A product is not

quality because it is hard to make and costs a lot of

money . . . This is incompetence. Customers pay

only for what is of use to them and gives them value.

Nothing else constitutes quality.

Peter Drucker


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Time

TotalCosts Alternative

Perpetual

Pavement

Economics

Why are Perpetual Pavements


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Why are Perpetual Pavements

Important?

Lower Life Cycle Cost

Better Use of Resources

Low Incremental Costs for Surface Renewal

Lower User Delay Cost

Shorter Work Zone Periods

Off-Peak Period Construction

Rehabilitation


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{50 - 100 mm

S

t r u c t u r e R e m a i n s I n t a c t

Possible Distresses› Top-Down Fatigue

› Thermal Cracking

› Raveling

Solutions

› Mill & Fill

› Thin Overlay

High Quality SMA, OGFC or Superpave

20+ Years Later

Rehabilitation


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Life Cycle Costs

Important to consider

Initial Costs

Rehabilitation and Maintenance Costs

Reconstruction costs

Should break costs into

Agency costs

User Costs

Time

Design Comparison Low


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Design Comparison – Low

Volume 50 year design

1 mile, 2 Lane, 12 ft lanes

Traffic: 5000 ADT (Rural Setting)

Muench, et al., 2004

Subgrade

12” Granular Base

6” HMA

6” Granular Base

3” HMA

Conventional($230,000)

Perpetual($360,000)


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session 4 - long life pavement and preservation.pdf

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