SHRP-P-654

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SHRP-P-654

SHRP Procedure for TemperatureCorrection of Maximum Deflections

Strategic Highway Research Programational Research Council

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Strategic Highway Research Program Executive Comnnittee

John R. Tabb, ChairmanMississippi High way Deparfm enWilliam G. AgnewGeneral Motors Research (retired)E. Dean Carlson, ex oficioFedLral Highway AdminishationA. Ray ChamberlainColorado Deparmtent of HighuaysMichael J. Cuddyh'ex York Deparmtent of TransportationRaymond F. DeckerUniversiw Science Partners Inc.Thomas B. Deen, ex o f ic ioTransportation Research BoardThomas M. DownsNew Jersey Department of TransportationFrancis B. Francois, ex o f ic ioAmerican Association of State Highway and Transportation OficialsWilliam L. GilesRuan Transportation M anagement SystemsJack S . HodgeVirginia Department of TransportationDonald W. LucasIndiana Deparfment of TransportationHarold L. MichaelPurdue UniversityWayne MuriMissouri Hi gh wq and Transportation DepartmentM. Lee Powell, 111Ballenger Paving Cornparry h c ,Henry A Thomason, Jr.T e rn Deparfment of Highways and Public TransporfationStanley I. WarshawNational Institute o/Stan rds and Technolo gyRoger L. YarbroughApcon Corporation

Key S H R P Staff

Damian J. KuliahExecutive DirectorGuy W. HazerImplementation ManagerEdward T. HarriganAsphalt Program ManagerKathryn Harrington-HughesCommunicatiors DirectorDon M. HarrioltConcrete & SnucturedHighwayOperations Program ManagerHany JonesFinance & Adrninislration Director

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SHRP-P-654

SHRP Procedure for TemperatureCorrection of Maximum Deflections

PCSLaw Engineering

Strategic Highway Research ProgramNational Research Council- Washington, DC 1993

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SHRP-P-654Coiitract P-00 1Program Manager: Neil F.HawksProject Manager: Cheryl Allen RichterProduction Editor: Marsha BarrettProgram Area Secretary: Cynthia BakerAugust 1993key words:deflection testingfalling weight deflectometerF W Dtemperature correction

Strategic Highway Research ProgramNational Academy of Sciences2101 Constitution Avenue N .W.Washington, DC 20418(202) 334-3774

The pub lication of this report does not necessarily indicate approval or endorsement of rhe findings, opinions,conclusions, or recommendations either inferred or specifically expressed herein by the National Academy ofSciences, the United States Government, or the American Association of State Highway and TransportationOfficials or its member states.

1993 National Academy of Sciences

350lNAPl893

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Acknowledgments

The research described herein was supported by the Strategic Highway Research Program(SHRP). SHFW is a unit of the National Research Council that was authorized by section128 of the Surface Transportation and Uniform Relocation Assistance Act of 1987.

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TABLE OF CONTENTSPage

INTRODUCTION . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . 1FWDCHECK TEMPERATURE CORRECTION PR OCED URE . . . . . . . . . . . . . . 1SENSITIVITY ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13SUMMARY . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . 19REFERENCES ................................................... 22

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LIST OF FIGURESFigure Page

1 Actual Testing Conditions and Pavement Structure ..................... 32 Hypothetical Trend of Field Temperatures ........................... 43 Testing Conditions and Pavement Structure Used in Correction Procedure . . . 54 Components of Maximum Surface Deflection ......................... 95 Hypothetical Pavement Sections .................................. 146 Summary of Sensitivity Analyses Temperature = 20. 60. and 100 O F ) . . . . . . 167 Effect of AC Thickness on Temperature Correction . . . . . . . . . . . . . . . . . . . 178 Effect of Subgrade Modulus on Temperature Correction . . . . . . . . . . . . . . . 189 Temperature Correction Factor Char t s for Flexible Pavements(AC Thickness Range: 2 to 12 inches) ............................. 2010 Temperature Correction Factor Charts for Composite Pavements(AC Thickness Range: 2 to 12 inches) ............................. 21

LIST OF TABLESTable Page

1 62 Values Used in Sensitivity Analysis ............................... 15

Layer Elastic Modulus as a Function of Material Type . . . . . . . . . . . . . . . . . .

v i i

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Abstract

Nondestructive deflection testing using falling weight deflectometers (FWDs) is oneelement of the monitoring effort currently underway by the Strategic Highway ResearchProgram (SHRP) for the Long-Term Pavement Performance (LTPP) study. Becauseaccurate data are key to the success of the LTPP study, SHRP has implemented a numberof measures to ensure the quality of the deflection data. They include equipm entcomparison and calibration, standardized field testing procedure and field data checks, andquality assurance software.In turn the quality assurance software includes a program called FWDCH ECK which hasbeen developed to analyze deflection data for, among other things, overall reasonablenessfrom a structural capacity viewpoint. In the case of asphaltic concrete pavements, thisstructural capacity analysis follow s the AASH TO direct structural number procedure. Sinceasphaltic concrete materials are temperature dependent in nature, measured deflections andhence the structural capacity of the pavement vary with temperature. Thus, a procedure tocorrect measured maximum deflections to a standard temperature is required so that thecom parison of predicted versus expected structural capacities is a valid one. Th is reportdocum ents the temperature correction procedure developed for and used in theFWDCHECK program.

i x

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INTRODUCTIONSHRP's Long-Term Pavement Performance (LTPP) study involves extensive monitoring ofnumerous pavement sections located throughout North America. One aspect of the LTPP datacollection is deflection testing, which provides information on structural capacity and materialproperties. Because accurate data is key to the success of the LTPP study, SHRP hasimplemented a number of meaSureS to ensure the quality of deflection data. They include:equipment comparison and calibration, standardized field testing procedures and field datachecks, and quality assurance software. For the final stage in the quality assurance process, acomputer program called FWDCHECK has been developed to analyze deflection data for testsection homogeneity, the degree to which test pit data is representative of the section, thepresence of data outliers withinthe section, and overall reasonableness from a structural capacityviewpoint (1).The last set of deflection data checks in FWDCHECK -- overall reasonableness from a structuralcapacity viewpoint -- involve the computation of pavement structural capacity and thecomparison of the results to what one might expect based on known layer thicknesses andmaterial properties. In the c se of flexible (asphalt concrete or AC) pavements, this structuralcapacity analysis follows the AASHTO direct structural number procedure. The outer deflectionbasin data are used to estimate the subgrade modulus and this parameter, along with themaximum deflection, is used to directly estimate the effective structural number (SN)of thepavement system.Because of the temperaturedependent nature of the asphalt concrete modulus, however,measured deflections and hence the structural capacity (or SN value) of the pavement will alsovary with temperature. Thus, a procedure to correct the measured maximum deflection to astandard temperature is required so that the comparison of predicted versus expected SN valuesis a valid one. Also since the AASHTO structural number or SN value is computed at astandard temperature of 68 F, maximum deflection measured in the field must be corrected tothis standard temperature. This report documents the temperature correction proceduredeveloped for and used in the FWDCHECK program.FWDCHECK TEMPERATURE CORRECTION PROCEDUREThe maximum deflection temperature correction procedure incorporated in the FWDCHECKprogram is based upon the following relation:

where Dr = temperature correction factor, 60,= maximum surface deflection at standardtemperature of 68 F, and 6of = maximum surface deflection measured in the field (i.e., attest temperature).

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The loading, structural and temperature factors affecting the maximum measured deflection,6oj, are illustrated in Figure 1. They include:1.2.3.

Loading Factors - applied load ( P), radius of circular load plate (ac), andplate contact pressure (pc).Structural Factors - number of layers (n), layer thicknesses (hi), layer elasticmoduli (EJ, and layer Poissons ratios (ui).Temperature Factors - temperature of the asphalt concrete urface layer (TJ;(Note: mid-depth temperature is used in the FWDCHECK program analysis).The loading factors P, a,., and pc are always known for a given deflection basin test (storedin the deflection data file). Layer thicknesses (hi) are also known from coring and test pitinformation collected at both ends of the pavement section; they are assumed to remainconstant throughout the section. The mid-depth temperature of the AC surface layer TJcan be estimated for each deflection basin based on temperature readings taken throughoutthe test day, at both ends of the pavement section and at various depths; Figure 2 shows atypical trend of mid-depth temperature versus time of testing. The only unknown factorsare the layer elastic moduli (Ei) and Poissons8 atios (ui).The loading, structural and temperature factors used in the determination of thetemperature correction factor are illustrated in Figure 3. Figure 3a represents the actualconditions at the time of testing, Th while Figure 3b represents the: conditions at thestandard temperature of 68F. The major difference between the two sets of conditions isthe mid-depth surface temperature, which in turn affects the elastic modulus of the ACsurface layer, Ei, and hence the maximum deflection, 6,. The loading factors and layerthicknesses are the same as those measured in the field. Because layer moduli and Poissonsratios are generally unknown, he following assumptions have been ma.de:

All layers are homogeneous and linearly elastic (even though non-linearity isbuilt into the FWDCHECK analysis).All layers have a Poissons ratio of 0.5.With the exception of the AC surface and subgrade layers, the elastic modulusof all other layers is a constant value defined according to material type; seeTable 1.

The subgrade elastic modulus is determined from the composite moduli predicted as afunction of geophone location (i.e., radial distance). More specifically, it is assumed thatthe subgrade modulus is equal to the minimum value in the composite modulus-radialdistance relationship. Composite moduli are calculated at each radial distance using themeasured deflection basin data as input into Boussinesqs one-layer deflection equation (2):

or2

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PI

E2 I.2

FIELD CONDITIONS ATTEMPERATURE = Tf

Figure 1 - Actual Testing Conditions and Pavement Structure3

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Mid - DepthTemperatureFAnalysisTemp.

IFirst l i m e ofTemp. DeflectionReading Test

(D From MeasuredValues

Last Temp,, l i m e ofReading Day

Note: Temperature data is interpolated in orderto provide for the best estimate at the timeof testing

Figure 2 - Hypothetical Trend of Field Tempera.tures4

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P P

l l ,Pc

CONDITIONS USED IN MODELAT TEMPERATURE= Tf CONDITIONSUSED IN MODELA T TEMPERATURE = 68 F

Figure 3 - Testing Conditions and Pavement Structure Used in Correction Procedure

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Table 1 Layer Elastic Modulus i t s a Function of Material Type

Material ypeUncrushed Gravel

Material Code Elastic Modulus hi)302 20.0

Crushed StoneCrushed Gravel

303 45.0304 30.0

Crushed SlagSandFine Soil-Agg. Mixture

~~

305 50.0306 10.0307 15.0

Portland Cement Concrete I 700- I 5,Oc10.0

Coarse Soil-Agg. MixtureSand Asphalt

6

308 20 o320 200.0

Asphalt Treated MixtureCement Aggregate MixtureEconocreteCement T reated SoilLe an ConcreteSand-Shell M ixtureLimerock, CalicheLime Treated SoilSoil CementPozzolanic-Agg. MixtureCracked & Seated PCC

321 300.0331 750.0332 1,500.0334 100.0336 1,5OO.O337 75.0338 200.0339 75.0340 200.0341 500.0730 1,Oco.o

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where:E C = composite modulus;r = radial distance;Pca,6C

= contact pressure applied by NDT device;= radius of contact of NDT device;= Poisson's Ratio of the subg-rade ( = 0.5);= measured deflection at given radial distance; and= deflection constant equal to the lower of [l.llog (r/ac) + 1.151 and[0 .5 pe + 0.8751.

Th e elastic m odulus of the asphalt concrete layer, both a t field and standard tem peratures,is determined by means of the following dynamic modulus predictive equation developedby the Asphalt Institute:foglo E' = 0.553833 + 0.028829e,y01m3 - 0.03476V0 0.070377qm

(2)(13 0.49U2Sbg/ 0 - 0.00189[1:' O P,OJ *,I.'] + 0.931757fom4+ o . m j z p p-7where: E' = AC modulus 16 psi);pZm = percent weight passing the No. 200 sieve (%);f = test frequency of load wave c p s or Hz ;v. = percent air voids in mix (%);

? -70;106 = AC Viscosity at 70F (106 poises);tP = AC temperature ( F); andpAC = percent asphalt content by weight of mix (%).To simplify the temperature correction analysis, the following typical asphalt concreteproperties were assumed:

P200 = 5.0%f = 20Hzva = 4.0%770; 10^6 = 1.5 x 106 poisePK = 5.0

Thus, the AC modulus predictive equation (Eq. 1) is reduced to:log,, E = 6.464 - 0.000145r, ~9*8u (3)

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Having established th e various loading, structural and temp erature factors, the maximumdeflection response of the pavem ent (i.e., directly und er th e load plate) is pred icted for boththe assumed field and standard tem pera ture conditions. To accomplish this, a closed formsolution was developed based on equivalent layer theory and Boussinesq's one-layerdeflection equation s. Th e derivation of this solution is presented below.The m aximum surface deflection is equal to the sum of the compressions #ofeach pavementlayer plus the deflection at the interface of the bottom of layer (n-1) nd the top of thesubgrade, as shown in Figure 4. The compression of each layer is determ ined by subtractingthe interface deflections which occur just above and below the pavem ent layer. Thisdifference represents the cumulative strain that is contribu ted by th e pavem ent layer. Th eremainder of the surface deflection results from strains developed in the underlying layers.The compression of each pavement layer can be determined in this manner with theexception of the subgrade. If the subgrade is assumed to have an infinhe thickness, nocompression will occur, therefore 100 percent of the interface deflection at the top of thesubgrade con tributes to the total surface deflection. Thus, the final equation for the totalsurface deflection is as follows:

total surface deflection;deflection at top of layer 1;interface deflection at bottom of layer 1;interface deflections at the top of layer i;interface deflections at the b ottom of layer i; andinterface deflection at the top of subgrade.Interface deflections are determined using Boussinesq's one-layer deflection equation.When using these equations, multiple layers are transformed into a single, hom ogeneousmaterial layer. Specifically, when determining the com pression of layer i, all layers aboveit are transformed in to an equivalent ma terial having th e s am e characteristics as layer i (i.e.,same Ei and ui). Th e thicknesses of these transformed layers are such th at t he stiffness ofeach layer remains the same (i.e., as before the transformation).The stiffness of any given pavement layer, S, s defined by:

where Ej, hj and uj are the elastic modulus, thickness and Poisson's ratio of layer j,respectively. Thus, f a layer characterized by these properties is transformed into an8

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P

Pavement t LoadedPavement

6, = tiv6 , = 6c1 + 6cz + ... + + b

Note; hipmp) as shown in the above illustration refers to the compressed layerth~ckness fter the pavement is loaded.

Figure 4 - Components of Maximum Surface Deflection9

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equivalent material (having E, hi and uJ but the stiffness remains the same, the followingrelationship must hold true:

Or, rearranging the transformed thickness equation, h;can be solved as follows:

where:

The OL function used in the FWDCHECK temperature correction procedure was determinedby comparing (and analyzing) deflection results generated from hundreds of Chevron runswith those generated using the transformed section approach discussed next. The resultstypically ranged from 01 = 0.8 to 0.9.In the case of a one-layer pavement system, the maximum deflection directly under thecenter of the load plate can be estimated from the following Boussinesq equation:

Furthermore, if the Poissons ratio of all layers is assumed to be p i = pj = 0.5, then thetransformed thickness equation is reduced to:h; = hj JE;

To compensate for errors inherentin this approximate procedure, an adjustment factor, 01,is typically incorporated into the thickness transformation equation:3 -

h; = ah fi

where:z = depth from surface;rFb

= radial distance from load; and= Boussinesq one-layer deflection factor, which in turn is defined by:10

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If the Poissons ratio for this one-layer system is assumed to be p = 0.5, then the aboveequation is reduced to:

However, since pavement structures generally consist of multiple layers, the concepts oflayer thickness transformations and interface deflections must be incorporated into theBoussinesq one-layer deflection equation. The maximum surface deflection is determinedas follows:

1. The first layer (i.e., AC surface) of the pavement structure does not requiretransformation because no layers lie above it. Therefore, the interfacedeflections at the top and bottom of the layer (& and fS B) are defined by:

2O.75pca,a;, = Eland

where El, h, and u, are the elastic modulus, thickness and Poissons ratio ofthe AC surface layer.2. To determine the interface deflections for each of the remaining pavement

layers above the subgrade, all layers above the one in question (i.e., layer i)are transformed into an equivalent, single material characterized by Eiand ui.This process is shown below:

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2 20.75pcac 1 0.75pcacam = FhT

and20.75pcaf 1m = Fbis

where Ej, hj and uj are the elastic modulus, thickness and Poisson's ratio oflayer j.3. The interface deflection at the top of the subgrade, a is determined asfollows:

4. As indicated earlier, the maximum surface deflection is e:qual to the sum ofthe compression in each layer plus the interface deflection at the top ofsubgrade:

Substituting the interface equations (presented in Steps No. 1 through 3above) into the maximum surface deflection equation yields:

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This last equation is used in the FWDCHECK temp erature correction procedure to estimateboth the maximum surface deflection at field temperature, 6ob nd the maximum surfacedeflection at the standard temperature of 68 F, 60,. The only difference in these twocalculations is the elastic modulus assigned to the AC surface layer -- Elf (at fieldtemperature) and E,, (at 68F). In turn, the temperature correction factor, Dr, isdetermined from 6of and 60, s follows:

This factor is only used to temperature correct maximum deflections, after the subgrademodulus has been established.SENSITIVITY ANALYSISIn order to assess the influence of the various factors used to determine the temperaturecorrection factor, Dr, a sensitive analysis was undertak en. These factors included:

1.2.3. Layer Poisson's ratio

Asphalt Concrete thickness (when used as a surface layer)Layer moduli (other tha n surface layer)

Deflection temperature correction factors were fust determined for the four hypotheticalstructures shown in Figure 5, which include two and three layer flexible structures and twoand th re e layer composite structures. Th e influence of each para m ete r on the temperaturecorrection factor was determined by varying the values shown in Figure 5 to those shownin Table 2.The analysis results are summarized in Figure 6. As can be observed, changes in thethickness of the asphalt concrete layer and the elastic modulus of the subgrade have thegreatest effect on the temp eratu re correction factor, Dr. Th e impa ct of these two factorsupon Dr is further illustrated in Figures 7 and 8, which show the change in Dr due tochanges in either AC layer thickness or subgrade modulus and tem pera ture. Th e remainingfactors, Ei and pi, had little to no effect on Dr (up to 7% change in Dr, see Figure 6).It should be noted that when determining the temperature correction factor, the asphaltconcrete m odulus is predicted from the Asphalt Institute dynamic modulus equation and thesubgrade modulus is calculated from the outer geophone deflection readings. Therefore,

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Section 1 Section 2

.

1 1 6 'AC, E (temp), p 0 . s

I LSG.E=15ksi,p=0.45

Section 3AC, E (temp), p = 0.35

I 1l2GB,E-30ksi, p = 0.4

AC, E (temp), p = 0.35PCC,E=5000ksi, p-0.15GB, E 30ksi, p 0.4

686

SG, = 15 ksi, p -0.45Section4

I GB, E -30 si, p 0.4 16IB, E- 30 si, p - 0.4

SG, E 15 ksi, p 0.45

AC = Asphalt ConcreteGB = Granular BaseSG =SubgradeFCC = Portland Cement Concrete

Figure 5 Hypothetical Pavement Sections14

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Table 2 Values Used in Sensitivity Analysis

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30.0 1

g310.0

a 20 0/J 15.0p 10.05.0

p40.0.- Sectiull sectim2 sectlol l3 Section4

Field Temperature 20 deg F

yloj25.0 bet 25*0*g20.0~ 1 5 . 0b10.0i 5.0

0.0I saction1 sa a 2 sect ion3 sbction4field Temperature 60 eg P Field Tern 100 deg F

ACIhichese Surface PoissonsRatioBase Elastic Modulus BasePoissonsRatioSubbase Elastic Modulus SubbasePoiasons RatioSubgrade Elsstic M d u e Subgrade Poissoas Ratio

Figure 6 - Summary of Sensitivity Analyses (Temperature = 20,60, nd 100F)

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.

10.0 -90.0 -

80.0 -* 70.0 -.B 60.0 -8

6)c.r 2 40.0

3 30.020.0

10.00.0

0 10 20 30 40 50 6 70 80 90 100 110 120Field Temperature, deg FPercentage Change in Dr

Subgrade Modulus 5 to 50 hi

@ Section 1Section 2

rJ S&m3section4

Figure 7 Effect of Subgrade Modulus on Temperature Correction

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Percentage Change in Dr (h = 2 to 12 )

90.0 -80.0 -0.0 -A3 60*o8 50.0

b 40 08 30.020.010.00.0

8

10 20 30 40 50 60 70 80 90 100 i io iioField Temperature, deg FFigure 8 - Effect of AC Thickness on Temperature Correction

Section 1section 2section3.........Section4

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changes in Dr are accurate when due to changes in AC thickness and subgrade modulus.Alternatively, the parameters that are assumed in the procedure -- & through En-lnd pithrough p,, - have little effect on th e resulting te m pera ture correction factor.Typical temperature correction curves have been developed for flexible pavements withweak subgrade support, flexible pavements with strong subgrade support, compositepavements with weak subgrade support and composite pavements with strong subgradesupport based on analysis results. Th ese curves a re shown in Figures 9 and 10. In them,a weak subgrade soil is defined as having an elastic m odulus of 10h i o r less, wh ile a strongsubgrade soil is defined as having a modulus greater than 20 h i . Prior to implementation,however, it is recommended that temperature correction curves be developed for a widerrange of anticipated subgrade modulus values.SUMMARYA tem perature correction procedure h as be en developed and implem ented in theFWDCHECK software to correct measured maximum surface deflections to a standardtemperature. Documentation of the procedure is included in the text of this report. Asummary of some of the features of the procedure are listed below:

The procedure isbased on a multi-layer analysis so that the p roperties of eachlayer within th e pavem ent stru cture ar e considered.Only the change in the compression of the AC surface layer due totemperature changes is consid ered in the procedure.The multi-layer procedure conside rs th e incompressibility of PCC laye rs muchbetter than the o riginal two-layer proced ure.Values assumed in the proced ure -- Ei and pi for base and subbase layers --have very little to no effect on the resulting temperature correction factor.Predictions of the AC modulus as a function of temperature a re based on theAsphalt Institute procedures 3).The procedure can be made more accurate if properties of the AC mix arek n O W n .The estimate of the subgrade modulus, which has an effect on Dry s based onactual deflection mea surements (ou ter geo phone readings).

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20

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1.5 1

0.3 .0.2 .0.1 -

8 1.51.4

12

I .o 1.33 1.2Cr, 1.1Y8 lP 0.98 0.80.7U 0.6z

212

8 0.11 , ,O O 20 40 60 80 100 120

Field Temperature,"FComposite Pavements - Weak Subgrade

dP141.41.31.21.110.90.80.70.60.50.4

2I

Figure 10 - Temperature Correction Factor Charts for Composite Pavements

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REFERENCES1. Strategic Highway Resear ch Program: Analysis of Section Homogeneity, Non-Representative Test Pit and Section Data, and Structural Capacity -FW DC HEC K, Version 2.00, Strategic Highway Research Program, April 1992.Rada, G.R., W itczak, M.W. and Rabinow , S.D., A Compa.rison of AASHTOStructural Evaluation Techniques using NDT Deflection Testing , TRB,Transportation Research Record 1207, Washington, D.C.: 1988.Th e Asphalt Institute, Research and Development of The A sphalt Institute'sThickness Design Man ual (MS-1) Ninth Edition , Research Rep or t No. 82-2,College Park,Maryland, August 1982.

2.

3.

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Long-Term Pavement Performance Advisory CommitteeChairmanWilliam J. MacCreeryW.J. MacCreery, Inc.David AlbrightAlliance for Transportation ResearchRichard BarkdaleGeorgia Institute of TechnologyJames L. BrownPavement ConsultantRobert L. ClevengerColorado D epartment of HighwaysRonald CollinsGeorgia Department of TransportationGuy DoreMinistere des Transports de QuebecCharles E. DouganConnecticut Department of TransportationMcRaney FulmerSouth Carolina Departmentof Highways and Public TransportationMarlin J. KnutsonAmerican Concrete Pavement AssociationHans Jorgen Erlman LarsenDanish Road Institute. Road DirectorateKenneth H. McGheeConsultant Civil EngineerRaymond K . MooreUniversiv of KansasRichard D. MorganNational Asphalt Pavement AssociationWilliam R. MoyerPennsylvania Department of TransportationDavid E. NewcombUniversiy of MinnesotaCharles A. P ryorNational Stone AssociationCesar A.V.QueirozThe World BankRoland L. RizenbergsKentucky Transportation CabinetGary K. RobinsonArizona Department of TransportationFrederic R. RossWisconsin Deparrment of Transportation

Kenneth R. W ardlawon Chemical Corporation

Marcus WilliamsH.B. Zachry CornpayLiaisonsAlbert J. Bush, 111USAE Waterways Erperiment StationLouis M. PapetFederal Highway AdministrationJohn P. HallinFederal Highway AdministrationTed FerragutFederal H ig hw q AdministrationFrank R McCullaghTransportation Research BoardExpert Task GroupPaul D. A ndersonMountainview Geotechnical Ltd.Robert C. BriggsTexas Department of TransportationAlbert J. Bush, 111USAE Waterways Erperimental StationBilly G. ConnorAhska Department of TransportationWilliam EdwardsOhio Department of TransportationJohn P. H allinFederal Highway AdministrationFrank L. Holman, Jr.Alabama Highway DepartmentWilliam J. KenisFederal H ighway AdministrationJoe P. MahoneyUniversity 01Washingtonarry A ScofieldArizona Transportation Research Center

Richard N . Stubstad Dymtes t C oml t i ng , Inc .Marshall R. ThompsonUniversiy of IllinoisPer UllidQTechnical Universiy of DenmarkJacob Uzan