Project-Level Pavement
Evaluation of
Existing Pavements
Class Objectives
 Describe data required for project-level
evaluation of existing pavements
 Determine AC and PCC pavement layer
properties
General Project-Level
Pavement Evaluation
Rehabilitation design requires an
evaluation of the existing pavement to
provide key information
Determining the extent of damage and
material properties of the in-place layers is
the most critical challenge in pavement
evaluation
Many failures of Pavement Rehabilitations
are due to inadequate pavement
evaluations
General Project-Level
Pavement Evaluation
Level of Detail and Factors to Consider:
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Agency Level (Local, County, State)
Functional Class of Roadway (local, collector, arterial)
PMS Recommended Treatment Type
Pavement Evaluation Cost
Pavement Design Methodology
General Project-Level
Pavement Evaluation
Consists of:
 Structural adequacy (Load Related)
 Functional adequacy (User Related)
 Drainage adequacy
 Shoulder condition
 Material durability
 Variation along project
 Constraints
 Miscellaneous (e.g., joint condition)
Factors for Rehabilitation
Design
• Pavement has significant and extensive levels
of distress that exceed the user’s failure criteria,
condition of the existing pavement may be
determined from results of the visual distress
surveys
• Pavement has exhibited no structural distress,
field and laboratory testing become important to
determine the condition of the existing pavement
layers
• Pavement has marginal levels of distress, the
results from the visual distress survey may be
used to determine the location and frequency of
the field tests and cores
Data Requirements
 Historical—Data collected prior to current
pavement evaluation
 Benchmark—Data collected as part of
the current pavement evaluation process
Benchmark Data
 Is there any load-related distress?
 Are there areas with excessive deflections?
 What is the effect of lack of maintenance
on pavement structural integrity?
 What is the amount of previous
maintenance and rehabilitation work?
Benchmark Data
 Is there a systematic variation in pavement
structural condition at these locations?
 What are some of the potential
constraints?
Project-Level Evaluation
Project-Level Evaluation
IRI
Project-Level Evaluation
Project-Level Evaluation
Project-Level Evaluation
Project-Level Evaluation
Project-Level Evaluation
Field Evaluation Plan
Evaluation Plan
 Obtain and compile historical data
 Preliminary data evaluation
 Detailed survey
Evaluation Plan
 Second/final data evaluation
 Final report
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Documentation of results
Recommendations on feasible rehabilitation
alternatives
MEPDG INPUTS
MEPDG Inputs for Rehab
Historical Data
 Required information:
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Site (e.g., traffic, environment, and
subgrade)
Design (e.g., layer thickness, material
properties)
Construction records (as built)
Historical Inputs
Historical Inputs
Historical Inputs
Historical Inputs
Historical Inputs
Historical Inputs
Historical Inputs
Historical Inputs
Detailed Survey
 A detailed survey typically consists of:
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Visual distress survey
Nondestructive testing (NDT), FWD including
the backcalculation of layer elastic moduli
Destructive testing
Laboratory analysis and materials
characterization
All Lanes in each direction
May include Shoulders
Visual Distress Survey
 Detailed visual distress survey must be
conducted to determine the amount, type
and severity of load-related distress
 LTPP Distress Identification Manual is a
good source of information for agencies
with no local guidelines
Automated Visual Distress
Survey
Automated Visual Distress
Survey
Right of Way
Vertical Pavement View
Nondestructive Testing
 NDT procedures consist of the following:
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Layer Thicknesses (GPR)
FWD Deflection testing (material properties)
Ground Penetrating Radar
Ground Penetrating Radar
Results based on antenna frequency and dampness of
granular material
Ground Penetrating Radar
NDT-Deflection Testing
 Typical uses of FWD deflection data:
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Estimate layer modulus values for design
Determine areas with excessive deflections
Determine variability along project
To compute LTE for JCP
Void detection under PCC slabs
Falling Weight Deflectometer
Falling Weight Deflectometer
Falling Weight Deflectometer
 FWD tests have the following advantages:
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Simulate a moving wheel load
Measure pavement response-deflection basin
Require no fixed reference
Relatively fast
FWD Sensor Configuration
12 in.
12 in.
12 in.
12 in.
12 in.
12 in.
Loading Wheel Contact Area
Sensor
12 in.
Example of a Deflection
Basin
P
Load
plate
d0
AREA
d12
d36
d60
Backcalculation Software
 Flexible pavements
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BOUSDEF, EVERCALC, MODULUS,
MODCOMP, and others
 Rigid pavements
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Best fit spreadsheet, AREA
spreadsheet, and others
Load Transfer Efficiency
Load Transfer Efficiency
Others Uses of Deflection
Data -LTE
where
LTE =
u =

l
=
u
LTE  *100
l
Target is 70%
load transfer efficiency, percent
deflection 6 inches from unloaded
slab joint
deflection 6 inches from loaded slab joint
* If deflections are very small, LTE is not considered
Destructive Testing
Coring
Equipment
4 inch Cores
6 inch Cores
12 inch Cores
Core Samples
Dynamic
Cone
Penetrometer
Dynamic Cone
Penetrometer
17.7 lb hammer =
twice the
penetration of the
10.1 lb hammer
10.1 lb for soft
17.6 lb for hard
Use penetration of
17.6 lb hammer
Destructive Testing—Coring
and Materials Testing
 Subgrade resilient modulus, CBR,
R-value
 AC layers and stabilized base
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Resilient modulus
Asphalt stripping
Degradation
Erosion, bonding
Layer thicknesses
Destructive Testing—Coring
and Materials Testing
 PCC
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Flexural strength
Elastic modulus
 Granular base and subbase
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Degradation
Contamination by fines
Resilient modulus, CBR, R-value
 Layer thicknesses
Sampled
Material
Disturbed and
Undisturbed
Samples
Laboratory
Testing
Resilient
Modulus
Mr
Ep
HMA Mixtures Tests
 Volumetric Properties
 Dynamic Modulus
 Creep Compliance
 Indirect Tensile Strength
 Asphalt Binder Classification
PCC Mixtures Tests
 Elastic Modulus of PCC
 Indirect Tensile Strength
 Flexural Strength
Unbound Layer Material Tests
 Resilient Modulus – Subgrade, Subbase,
and Base
 Volumetric Properties
 Soil and Aggregate Classifications
Pavement Cold Milling
Structural Adequacy
Assessment
 Current structural adequacy based on
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Type, severity, and extent of load-related distresses
In-situ material properties (coring and testing)
Analysis of pavement response to loading
(deflection testing)
 Future structural adequacy based on
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Remaining life
Assessing Current Structural
Adequacy using Distress DataFlexible (Interstate/Freeways)
Distress Type
Current Distress Level Regarded
As:
Adequate
Marginal Inadequate
Fatigue cracking, %
of total Lane miles
Longitudinal
cracking (WP), ft/Mi
Transverse cracks,
ft/Mi
<5
5-20
> 20
<265
265-1060
> 1060
<500
500-800
> 800
Rutting, inch
< 0.25
0.25-0.45
> 0.45
Assessing Current Structural
Adequacy using Distress DataFlexible (Primary Arterials)
Distress Type
Current Distress Level Regarded
As:
Adequate
Marginal Inadequate
Fatigue cracking, %
of total Lane miles
Longitudinal
cracking (WP), ft/Mi
Transverse cracks,
ft/Mi
<10
10-45
> 45
<530
530-2650
> 2650
<800
800-1000
> 1000
Rutting, inch
< 0.35
0.35-0.60
> 0.60
Assessing Current Structural
Adequacy using Distress DataFlexible (Secondary Roads)
Distress Type
Current Distress Level Regarded
As:
Adequate
Marginal Inadequate
Fatigue cracking, %
of total Lane miles
Longitudinal
cracking (WP), ft/Mi
Transverse cracks,
ft/Mi
<10
10-45
> 45
<530
530-2650
> 2650
<800
800-1000
> 1000
Rutting, inch
< 0.4
0.4-0.8
> 0.80
Assessing Current Structural
Adequacy using Distress Data-Rigid
LoadJPCP
Distress Level Regarded As:
Related Highway
Distress
Class Inadequate Marginal Adequate
Cracking Interstate
>10
5 to 10
<5
Faulting Interstate
>0.2
0.1 to 0.2
<0.1
Patching Interstate
>10
5 to 10
<5
Assessing Current Structural
Adequacy using In-situ Properties
Range
Mean
Variable
Material
Type
Elastic
modulus,
psi
PCC
AC
250,000
1,000,000
600,000
Base
resilient
modulus,
psi
ACtreated
Lean
concrete
Granular
100,000
500,000
250,000
Low
High
3,000,000 7,000,000 4,500,000
500,000
15,000
2,500,000 1,500,000
40,000
30,000
Shoulder Adequacy
Assessment
 Important because shoulder condition
affects pavement structural integrity and
shoulders may be used as temporary
lanes
 Use same load-related distresses to
assess shoulder condition
 Threshold values should be lower than
for the actual pavement
Variability Along Project
 Important for optimizing rehabilitation
strategy
 Main forms of variability that should be
identified includes:
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Variations along project
Lane-to-lane variations
Intersections and bridge approaches
Cut and fill sections
Pavement Analysis Segments
Pavement Analysis Segments
Example Test Section with
Uniform Deflections
Graphical Review
Deflection (microns)
400
350
SEN-1
300
SEN-2
250
SEN-3
200
SEN-4
150
SEN-5
100
SEN-6
50
SEN-7
0
-20
0
20
40
Stations (m)
60
80
Example Test Section with High
Variability in Deflections
Deflection (microns)
350
300
SEN-1
250
SEN-2
200
SEN-3
SEN-4
150
SEN-5
100
SEN-6
50
SEN-7
0
80
100
120
Stations (m)
140
160
Example Test Section with
Abrupt Change in Deflections
Deflection (microns)
600
SEN-1
500
SEN-2
400
SEN-3
300
SEN-4
SEN-5
200
SEN-6
100
SEN-7
0
80
100
120
140
Stations (m)
160
180
Selection of Feasible
Rehabilitation Alternatives
 Based on current structural condition
determine feasible rehabilitation options:
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Restoration (Preventive Maintenance)
Rehabilitation without overlays (Repairs)
Rehabilitation with overlays (Minor/Major)
Reconstruction
 Other factors such as functional adequacy,
drainage, etc., must be considered
Project-Level Pavement
Evaluation of
Existing Pavements
QUESTIONS?