Module 2-5Module 2-5
Field Sampling and Field Sampling and TestingTesting
Identify reasons for conducting field Identify reasons for conducting field sampling and lab testing sampling and lab testing
Describe typical Describe typical fieldfield sampling and testing sampling and testing proceduresprocedures
Describe Describe laboratorylaboratory test methods and test methods and their applicationstheir applications
Describe the use of field and laboratory Describe the use of field and laboratory test results in rehabilitation designtest results in rehabilitation design
Learning ObjectivesLearning Objectives
Reasons for Conducting Reasons for Conducting Field Sampling and Lab Field Sampling and Lab
TestingTesting Complement and verify NDTComplement and verify NDT
Absence of NDTAbsence of NDT
Diagnose causes (mechanisms) of distressDiagnose causes (mechanisms) of distress
Identify structural characteristics and layer Identify structural characteristics and layer material properties in existing pavementmaterial properties in existing pavement EconomicsEconomics RecyclingRecycling Emphasis on rehabilitationEmphasis on rehabilitation
Typical Field Sampling and Typical Field Sampling and Testing ProceduresTesting Procedures
Material specimen samplingMaterial specimen sampling CoringCoring AugerAuger Split-spoonSplit-spoon Shelby (push) tubeShelby (push) tube Test pitTest pit
Field testingField testing Dynamic cone penetrometer (DCP)Dynamic cone penetrometer (DCP) Ground penetrating radar (GPR)?Ground penetrating radar (GPR)?
CoringCoring Widely used method for:Widely used method for:
Laboratory test samplesLaboratory test samples Layer thickness determination (or Layer thickness determination (or
verification)verification) Visually characterizing layer material Visually characterizing layer material
types and conditionstypes and conditions
Relatively inexpensiveRelatively inexpensive
Coring plans used to assess variability Coring plans used to assess variability along a project along a project
CoringCoringRemoving a CoreRemoving a Core
CoringCoringLayer Thickness VerificationLayer Thickness Verification
CoringCoringDistress Cause IdentificationDistress Cause Identification
CoringCoringSampling ApproachesSampling Approaches
Uniform spacing, e.g., every 500 m Uniform spacing, e.g., every 500 m
Based on review of “strip” charts
Distance Along Roadway
CoringCoringSampling Locations and Sampling Locations and
FrequencyFrequency
Standard locationStandard location Outside laneOutside lane Outer wheel pathOuter wheel path
Frequency (no. of samples) depends on:Frequency (no. of samples) depends on: Variability (uncertainty)Variability (uncertainty) Project size (anticipated rehab cost)Project size (anticipated rehab cost) Traffic and safety issuesTraffic and safety issues
Typical spacing: 100 to 800 mTypical spacing: 100 to 800 m
Dynamic Cone Dynamic Cone Penetrometer (DCP)Penetrometer (DCP)
Device for measuring in-situ strength of Device for measuring in-situ strength of paving materials and subgrade soilspaving materials and subgrade soils
Correlated to California Bearing Ratio Correlated to California Bearing Ratio (CBR)(CBR)
Cone angle 60o
Handle
Hammer(17.6 lb)
Cone
Steel rod (0.64 in)
22.6 in
39.4 in(variable)
1 in = 25.4 mm1 lb = 0.454 kg
0.79 in
DCP DeviceDCP Device
DCP Testing ProcessDCP Testing Process
Example DCP ResultsExample DCP Results
No. of BlowsNo. of Blows
DepthDepth
Base
HMA
Subbase
Subgrade Soil
Ground Penetrating Radar Ground Penetrating Radar (GPR)(GPR)
HMAHMA
BaseBase
SubbaseSubbase
Subgrade SoilSubgrade Soil
GPR Transmitter/ReceiverGPR Transmitter/Receiver Conceptual OutputConceptual Output
Laboratory Test Methods Laboratory Test Methods and Their Applicationsand Their Applications
Type of materialType of material
Basic property being measuredBasic property being measured
Material’s state of stressMaterial’s state of stress
Test methods (and their applications) areTest methods (and their applications) are
dependent upon:dependent upon:
Typical Properties Typical Properties Measured in LabMeasured in Lab
GeneralGeneralPropertyProperty Various Test MeasuresVarious Test Measures
StiffnessStiffness MMRR, E*, R-value, E*, R-value
StrengthStrength CBR, indirect tension, CBR, indirect tension, unconfined compressionunconfined compression
CompactionCompaction , AVC, AVC
ConstituentsConstituents , AC, gradation, contaminants, AC, gradation, contaminants
PermeabilityPermeability kk
Volume StabilityVolume Stability PI, PI,
Resilient ModulusResilient Modulus Surrogate for Young’s Surrogate for Young’s
(elastic) modulus(elastic) modulus
Fundamental Fundamental engineering propertyengineering property
Loading conditions:Loading conditions:
EEMMRR
Triaxial compressionTriaxial compression Axial compressionAxial compression Indirect tensionIndirect tension
Resilient Modulus TestResilient Modulus TestTriaxial CompressionTriaxial Compression
Used primarily for Used primarily for testing of unbound testing of unbound materials materials (re-compacted (re-compacted specimens or push specimens or push tube samples)tube samples)
Resilient ModulusResilient ModulusMethod of DeterminationMethod of Determination
Strain,
Dev
iato
r S
tres
s,
D
PlasticStrain
ResilientStrain
Total Strain
P R
MR =D
R
Resilient Modulus TestResilient Modulus TestAxial CompressionAxial Compression
Used primarily Used primarily for testing of for testing of bound materials bound materials (prepared (prepared specimens or specimens or core samples)core samples)
OEM, Inc. © 2000
LoadLoadRamRamLoad Load
CellCell
LVDTLVDTGage LengthGage Length
Heavier duty test equipment is used Heavier duty test equipment is used to measure compressive strengthto measure compressive strength
Complex Modulus (E*)Complex Modulus (E*) a.k.a.: dynamic modulusa.k.a.: dynamic modulus
Applicable to bituminous materialsApplicable to bituminous materials
Equipment and test procedure almost Equipment and test procedure almost identical to resilient modulus under axial identical to resilient modulus under axial compressioncompression
Primary difference is in load pulse Primary difference is in load pulse (haversine vs. sinusoidal)(haversine vs. sinusoidal)
AASHTO 2002 Guide for Design of New AASHTO 2002 Guide for Design of New and Rehabilitated Pavement Structuresand Rehabilitated Pavement Structures
Hveem Resistance TestHveem Resistance Test(R-value) (R-value)
Stiffness measure for Stiffness measure for unbound materialsunbound materials
Standard axial stress Standard axial stress ((vv) is applied) is applied
R-value is basically the R-value is basically the ratio of the applied ratio of the applied vertical pressure (vertical pressure (vv) to ) to the developed lateral the developed lateral pressure (pressure (hh))
vv
hh
150150mmmm
100 mm100 mm
California Bearing Ratio California Bearing Ratio (CBR) Test(CBR) Test
Strength measure for Strength measure for unbound materialsunbound materials
Piston advanced at Piston advanced at 1.3 mm / min. rate1.3 mm / min. rate
Measure load at 2.5 Measure load at 2.5 mm penetration (Pmm penetration (P2.52.5))
CBR = 100CBR = 100(P(P2.52.5/P/Pstdstd))
SaturatedSaturatedSpecimenSpecimen
50 mmdiameter
piston
150 mm
180mm
Indirect Tension TestIndirect Tension Test a.k.a.: Splitting tension or split tensile testa.k.a.: Splitting tension or split tensile test
Used to determine the tensile strength Used to determine the tensile strength and/or Mr of any bound materialand/or Mr of any bound material
100 or 150 mm diameter (D) 100 or 150 mm diameter (D) specimensspecimens
Sample length should be Sample length should be at least half the diameter at least half the diameter
Prepared samples or coresPrepared samples or cores
v
r D
Load, P
Length
Evaluating Pavement Evaluating Pavement LayersLayers
Subgrade SoilsSubgrade Soils
Soil classification (Unified or AASHTO)Soil classification (Unified or AASHTO)
Moisture content and densityMoisture content and density
DCPDCP
Resilient modulus:Resilient modulus: Measure in the labMeasure in the lab Backcalculate from NDT dataBackcalculate from NDT data Estimated from correlation with R-Estimated from correlation with R-
value, CBR, or other soil propertiesvalue, CBR, or other soil properties
Evaluating Pavement Evaluating Pavement LayersLayers
Unbound Base & Subbase LayersUnbound Base & Subbase Layers
Visual inspectionVisual inspection Layer thicknessLayer thickness Degradation or contamination by finesDegradation or contamination by fines
DCPDCP
Density and moisture contentDensity and moisture content
Resilient modulusResilient modulus
Evaluating Pavement LayersEvaluating Pavement LayersHMA Surface and Stabilized Base LayersHMA Surface and Stabilized Base Layers
Visual inspection of coresVisual inspection of cores Layer thicknessLayer thickness Stripping, segregation, erosionStripping, segregation, erosion
Asphalt content and gradationAsphalt content and gradation
Resilient modulusResilient modulus Lab measured (indirect tension)Lab measured (indirect tension) BackcalculatedBackcalculated
Other ConsiderationsOther Considerations Volume stabilityVolume stability
StrippingStripping
Seasonal variations in moistureSeasonal variations in moisture
PermeabilityPermeability
Use of Field and Lab Tests Use of Field and Lab Tests in Rehabilitation Designin Rehabilitation Design
Help characterize existing support and Help characterize existing support and quantify effect of deteriorationquantify effect of deterioration
Field and lab testing vary depending on:Field and lab testing vary depending on: Material type (i.e., subgrade soil, Material type (i.e., subgrade soil,
unbound base or subbase, and HMA unbound base or subbase, and HMA surface or stabilized base)surface or stabilized base)
Candidate types of rehabilitation Candidate types of rehabilitation treatments (for example, recycling treatments (for example, recycling justifies a higher level of lab testing)justifies a higher level of lab testing)
What are two situations where field What are two situations where field sampling and lab testing may be sampling and lab testing may be required?required?
What kind of sampling and testing would What kind of sampling and testing would you now consider?you now consider?
What is the motivation for resilient What is the motivation for resilient modulus testing?modulus testing?
Name two ways in which field/lab test Name two ways in which field/lab test results can be used in rehab design?results can be used in rehab design?
ReviewReview
Key ReferencesKey References Washington State Department of Washington State Department of
Transportation (WSDOT). 1995. Transportation (WSDOT). 1995. WSDOT Pavement Design GuideWSDOT Pavement Design Guide. . Washington State Department of Washington State Department of Transportation, Olympia, WA.Transportation, Olympia, WA.
Livneh, M. 1987. “The Use of Dynamic Livneh, M. 1987. “The Use of Dynamic Cone Penetrometer in Determining the Cone Penetrometer in Determining the Strength of Existing Pavements and Strength of Existing Pavements and Subgrades.” Subgrades.” Proceedings, 9Proceedings, 9thth Southeast Southeast Asian Geotechnical Conference.Asian Geotechnical Conference. Bangkok, Thailand.Bangkok, Thailand.