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Non-Destructive Pavement Testing at IDOT LaDonna R. Rowden, P.E. Pavement Technology Engineer
Non-DestructivePavement Testing atIDOT
LaDonna R. Rowden, P.E.Pavement Technology Engineer
Bureau of Materials and Physical Research
Physical Research Section
BridgeInvestigations
Unit
PavementTechnology
Unit
ProductsEvaluation
Unit
TechnicalServices
Unit
OperationsSub-Unit
Pavement DataManagement
Sub-Unit
Types of Testing
Pavement Surface Distress andRiding Quality
Skid Resistance (Pavement Friction)
Falling Weight Deflectometer (FWD)
Pavement Surface Distressand Riding Quality
Pavement Surface Distress
Six cameras record images from theroadway– Three front-facing perspective– One rear-facing– Two pairs of down-facing (only one set
collects at a time)
Images collected at a rate of 3 to 1,downward to perspective
International Roughness Index– Measurement relating how passengers
perceive the roughness of the pavement.– Pavement Profile analyzed using a
quarter-car simulation.– Collected in each wheelpath using lasers.– Recorded in inches/mile (mm/km).
Pavement Riding Quality
International RoughnessIndex (IRI)
Over 320Rough
191 to 320Medium
0 to 190Smooth
VALUERATING
Subjective Ratings for All Countries
Pavement Riding Quality
Rut Depth– Permanent deformation of the pavement
surface due to wheel loads.– Collected through lasers in each
wheelpath.– Recorded in inches (mm).
Pavement Riding Quality
RWP LWPCEN
LWGRWGRWG LWG
RWP CEN LWP
Calculations:Left Rut Depth: LWP-(CEN+LWG)/2Right Rut Depth: RWP-(CEN+RWG)/2Center Rut Depth: (RWP+LWP)/2-CEN
Pavement Surface Distressand Riding Quality
Information stored in a database.IDOT has 15 workstations forreviewing images and data.Select 5 predominant distresses.CRS value determined from distressesand ride quality data.
Pavement Inventory
Interstates Tested Annually
Non-Interstates Tested Biannually– Even Years: 1 (Cook Co.), 4, 5, 8, 9– Odd Years: 1 (Collar Co.), 2, 3, 6, 7
Special Requests
SKIDRESISTANCE
(Pavement Friction) Slippery
when
wet
Sharon HaasisBureau of Materials & Physical Research
SKID TRAILER
FRICTION NUMBER (FN)
• Represents the frictional properties of thepavement.
• Used to evaluate skid resistance of thepavement relative to other pavements.
• Used to evaluate the change in skid resistance of the pavement with time.
• FNt represents treaded tire measurements.
• FNs represents smooth tire measurements.
• Treaded tire measures microtexture of pavement.
• Smooth tire measures macrotexture of pavement.
FNt and FNs
• Microtexture– Irregularities of aggregate surface
– Measured by Treaded Tire
• Macrotexture– Drainage paths between aggregate
particles
– Measured by Smooth Tire
PAVEMENT PROPERTIES
• Standard Test Method for SkidResistance of Paved Surfaces Using aFull-Scale Tire– Test Speed of 40 mph
– Water sprayed under tire
– Brake applied
– Torque on axle recorded
– Friction Number calculated
ASTM E274
• HA - wet weather accident locations.
• NC - new construction and pavement rehabilitation sites.
• RR - reruns of the new construction jobs.
• MS - Miscellaneous test requests (Unknown construction contract numbers and special request jobs).
TESTING CATEGORIES
• Surface Course Age
• Traffic
• Seasonal Changes
• Speed
INFLUENCES
REASONS FOR FRICTION TESTING
• Evaluate Mixture Performance– Bituminous Mixture type determined by ADT level
• Mixture C: 0 – 5,000
• Mixture D: 5,001 – 25,000 (4-lane)5,001 – 60,000 (6-lane)
• Mixture E: 25,001 – 100,000 (4-lane)60,001 – 100,000 (6-lane)
• Mixture F: > 100,000
– PCC texture determined by speed limit• Type A Finish: > 40 mph
• Type A or B Finish: ≤ 40 mph
CATEGORICAL RATING GUIDELINES
FNt < 30 or
FNs < 15
Friction may be a factorcontributing to wetweather accidents
Contact:
Sharon Haasis, Research EngineerBureau of Materials & Physical Research
Or
LaDonna Rowden Pavement Technology Engineer
Bureau of Materials & Physical Research217-782-8582
QUESTIONS ?
Falling WeightDeflectometer (FWD)Testing at IDOT
Charles J. Wienrank, P.E.Pavement Analysis Engineer
What is an FWD?
Impulse loading device used forstructural evaluation of pavements.– Load is applied to pavement that
simulates truck or aircraft wheel loads.– Resulting deflections are measured using
a series of velocity transducers.– Deflection data used to analyze pavement
structure.
Deflection Basin
Advantages of FWD
Accurately models a moving wheel load.Does not damage pavement.Testing can be done rapidly and at alower cost than destructive testing.– 50 to 60 tests done per hour.– Less disruptive to traffic than destructive
testing.
Flexible Pavements
Determine structural adequacy of pavement.Determine uniformity of support along a projectand identify weak areas.Estimate subgrade and pavement layer elasticmoduli values.Determine overlay thickness requirements.Develop cost-effective maintenance andrehabilitation alternatives.
Sample Deflection Profile
05
10152025303540
0+00
6+00
12+00
18+00
24+00
30+00
36+00
42+00
48+00
54+00
60+00
66+00
Test Location
Defl
ect
ion
(m
ils)
Rigid Pavements
Locate areas of poor support beneath jointedconcrete pavements.Determine load transfer efficiency across jointsand cracks.Estimate subgrade and pavement layer elasticmoduli values.Develop cost-effective maintenance andrehabilitation alternatives.
IDOT’s FWD Program
Project Level Testing is ≥ 95%3 Main Areas– Local Agency Testing– Monitoring of Experimental Sections– Seasonal Variation Program
Local Agency Testing
Counties, Cities, Townships, Airports20 to 25 Projects / YearEstimate Remaining Life and OverlayThickness Requirements
Monitoring ofExperimental Sections
2/3 of TestingDowel Bar ExperimentATREL Test SectionsRubblizing ProjectsOpen-Graded Drainage LayersMechanistic DesignsMiscellaneous
Seasonal Variation Program
Monthly testing performed at 4locations in the Springfield area.Measured deflections can vary greatlydepending on temperature andmoisture conditions.Deflection data collected during non-critical period is adjusted to reflectworst-case scenario.
Questions?
LaDonna Rowden Sharon Haasis(217) 782-8582 (217) [email protected] [email protected]
Charles Wienrank(217) [email protected]
