pavement structural analysis of the design … pavement layer thickness and ... mr. curtis bleech...

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Report No. MIDOT-15953-2/1

Prepared for:

Mr. Curtis Bleech

Michigan Department of Tranpsortation

Construction and Technology Division/Laboratory

P.O. Box 30049

Lansing, Michigan 48909

Prepared by:

Harold L. Von Quintus, P.E.

ERES Consultants – A Division of Applied Research Associates

26 Stillmeadow

Round Rock, Texas 78664

August 2004

Pavement Structural Analysis of the

Design Recommendations for Reconstructing

I-96 (M-39 to Schaeffer Road)

Pavement Structural Analysis August 2004 Report No. 15953-2/1 ARA-ERES Consultants

ii

Report No. MIDOT-15953-2/1

Prepared for:

Mr. Curtis Bleech

Michigan Department of Tranpsortation

Construction and Technology Division/Laboratory

P.O. Box 30049

Lansing, Michigan 48909

Prepared by:

Harold L. Von Quintus, P.E.

ERES Consultants – A Division of Applied Research Associates

26 Stillmeadow

Round Rock, Texas 78664

Harold L. Von Quintus, P.E. August 2004

Texas Registration 46169


Design Recommendations for Reconstructing

I-96 (M-39 to Schaeffer Road)


iii

Executive Summary

I-96 between M-39 and Schaeffer Road, just west of Detroit, Michigan, is planned for

reconstruction in 2005. The Michigan Department of Transportation (DOT) completed a

design for the reconstruction of this segment of I-96 in accordance with the 1993

AASHTO DARWin program.(1)

The objective of this study was to analyze the proposed

flexible pavement layer thickness and material types recommended for this segment

along I-96. Two mechanistic-empirical (M-E) design/analysis methods were used to

analyze the pavement design. One of the M-E design/analysis methods was the same one

used to prepare A Simplified Catalog of Solutions, and the second one is the new M-E

Pavement Design Guide developed under NCHRP 1-37A.(2,3)

Results from these analyses suggest that the proposed pavement structure will be

adequate relative to cracking. In fact, the tensile strain calculated under the standard

design load is less than the value that has been typically assumed for the endurance limit.

The one concern is with rutting and distortion. Both M-E analysis methods predict levels

of rutting that exceed the allowable level of 0.50 inches within the analysis period. Using

a PG 76-22 asphalt in the top two layers (the wearing surface and leveling course) will

reduce the rutting to an acceptable level. Whether a PG 70-22P or PG 76-22 is used

should be defined based on asphalt or mixture modulus testing or some type of torture

test to ensure that the HMA mixtures will be resistant to rutting.

Prior to construction, it should be confirmed that the pavement materials meet or exceed

the assumptions used in design, regardless of the design method. It is also recommended

that sufficient testing be completed during construction to ensure that the design

assumptions are satisfied.


iv

Table of Contents

Section Page

1. Introduction .................................................................................................................... 1

2. Study/Design Objective ..................................................................................................... 1

3. Project Design Parameters ................................................................................................. 1

3.1 Design Traffic ........................................................................................................ 1

3.2 Subsurface Investigations – Soil Support Design Value ....................................... 5

3.3 Non-Frost Susceptible Material ............................................................................. 7

3.4 Hot Mix Asphalt Mixtures ................................................................................... 11

3.5 Subsurface Drainage System ............................................................................... 13

4. Mechanistic-Empirical Thickness Design-Evaluation Method ....................................... 13

4.1 Pavement Structural Design Assumptions........................................................... 14

4.2 Evaluation Criteria ............................................................................................... 15

4.3 Simplistic M-E Analysis Method......................................................................... 15

4.4 New M-E Pavement Design Guide Software ...................................................... 19

5. Summary of Evaluations.................................................................................................. 21

6. Limitations .................................................................................................................. 22

7. References .................................................................................................................. 23

Appendices:

A Summary of Truck Traffic Equivalent Single Axle Load Applications Computed

for the Base Year 2005 .................................................................................................... 25

B Summary of Repeated Load Resilient Modulus Tests Extracted from the LTPP

Database for the Michigan Sites ...................................................................................... 32

C Layer Properties and Pavement Responses Computed for the I-96 Design Cross

Section .................................................................................................................. 36

C.1 HMA Modulus Determination............................................................................. 36

C.2 Unbound Layer Modulus Determination ............................................................. 38

C.3 EVERSTRS Output for Fatigue Cracking Analysis ............................................ 40

C.4 EVERSTRS Output for HMA Rutting Analysis ................................................. 42

D Analysis of the Proposed Design Cross Section of I-96 Using the New M-E

Pavement Design Guide Software ................................................................................... 43


1

1. Introduction

I-96 between M-39 and Schaeffer Road, just west of Detroit, Michigan, is planned for

reconstruction in 2005. The Michigan Department of Transportation (DOT) completed a

design for the reconstruction of this segment of I-96 in accordance with the 1993

AASHTO DARWin program.(1)

Figure 1 shows the pavement design (material types and

layer thickness) resulting from that design procedure.

Mr. Curtis Bleech with the Michigan DOT requested that an analysis of that pavement

structural design be completed using a mechanistic-empirical method for a 20 and 40-

year analysis period. The purpose of this document is to present the analyses completed

for evaluating the design pavement cross sections (material types and layer thickness)

recommended for the reconstruction of I-96 (refer to figure 1).

2. Study/Design Objective

The objective of this study was to analyze the flexible pavement layer thickness and

material types recommended for the segment along I-96 between M-39 and Schaeffer

Road using two mechanistic-empirical (M-E) design/analysis methods. One of the M-E

design/analysis methods was the same one used to prepare A Simplified Catalog of

Solutions, and the second one is the new M-E Pavement Design Guide developed under

NCHRP 1-37A.(2,3)

3. Project Design Parameters

3.1 Design Traffic

The traffic parameters that were used to determine the design number of 80-kN (18-kip)

Equivalent Single Axle Loads (ESALs) in accordance with the 1993 AASHTO Design

Guide are summarized below and were provided by the Michigan DOT.

� Average Annual Daily Commercial Traffic in 2005 = 9,600

� Initial Annual ESALs, both directions = 2,382,720

� Directional Distribution Factor = 0.56

� Lane Distribution Factor = 0.70

� Compound Commercial Traffic Growth Rate = 2.0%


Design Recommendations for Reconstructing I-96 (M-39 to Schaeffer Road)


2

� 20-Year ESALs, one-way traffic = 22,694,400

� 40-Year ESALS, one-way traffic = 56,400,000

Figure 1 Pavement design resulting from the 1993 AASHTO Design Guide for

the reconstruction of I-96.

HMA TOP COURSE

HMA LEVELING COURSE

HMA BASE COURSE

AGGREGATE BASE

SAND SUBBSASE

SILTY CLAY SOIL

HMA Top Course (PG 70-22P);

1.5 inches; Air Voids = 7.5%;

Vbe=10.5%

HMA Leveling Course (PG 70-

22P); 2.5 inches; Air Voids =

7.5%; Vbe=10.5%

HMA Base Course (PG 70-22);

10 inches; Air Voids = 7.5%;

Vbe= 9.5%

OGDC Aggregate Base Course;

16 inches (21AA-MOD)

Crushed Stone Base

Sand Subbase, Class IIA; 8 inches

Low Plasticity, Firm Silty Clay

Soil

Geotextile Separator-Fabric


3

The truck traffic inputs for the new M-E Pavement Design Guide software, however, are

the actual truck volume distribution and axle load distributions. Table 1 shows the truck

traffic distribution that was used in this pavement design study. The Truck Traffic

Classification (TTC) group for this urban freeway was assumed to be 3.(3)

Figures 2–4

show the axle load spectra for the single, tandem and tridem axles, respectively.

Table 1 Truck Traffic Volume Distribution for the Base Year, 2005.

Truck Type Normalized Volume Distribution, %

4 0.90

5 11.6

6 3.6

7 0.2

8 6.7

9 62.0

10 4.8

11 2.6

12 1.4

13 6.2

Using the default normalized truck volume and axle weight distributions determined from

an analysis of the Long Term Pavement Performance (LTPP) traffic data and the

AASHTO equivalency factors, the number of 18-kip (80-kN) ESALs were estimated for

the base year for this section of I-96.(3)

Appendix A summarizes the computations for the

ESALs using the normalized axle load distributions that are expected for this urban

freeway. The number of ESALS was computed to be 4,411,425 in 2005 for both

directions, which is almost twice the value used in the 1993 AASHTO design procedure

(2,382,720 ESALs). The reason for this difference is not known, but indicates that the

global default distribution values embedded in the new M-E Pavement Design Guide

software may not be applicable to the truck traffic in Michigan, or at least should be

confirmed prior to full-scale use.

A lane distribution factor of 0.70 and a directional distribution of 0.56 were used to

compute the design-lane ESALs for 2005 – a value of 1,729,279. As noted above, the

ESALs determined from the volume and axle load normalized distributions

recommended for use in the new M-E Pavement Design Guide are greater than those

used in the design study completed by the Michigan DOT. The average number of 18-

kip (80-kN) ESALS per truck application determined using the normalized distributions

was computed to be 1.259 (refer to Appendix A).


4

0

10000

20000

30000

40000

50000

60000

70000

0 10 20 30 40 50

Single Axle Load, kips

Nu

mb

er

of

Mo

nth

ly S

ing

le A

xle

Lo

ad

s

Figure 2 Monthly single axle load distribution or spectra for the base year for

the segment of I-96 from M-39 to Schaeffer Road.

0

5000

10000

15000

20000

25000

30000

35000

0 20 40 60 80 100

Tandem Axle Load, kips

Nu

mb

er

of

Mo

nth

ly T

an

de

m A

xle

Lo

ad

s

Figure 3 Monthly tandem axle load distribution or spectra for the base year for



5

0

500

1000

1500

2000

2500

3000

3500

0 20 40 60 80 100 120

Tridem Axle Load, kips

Nu

mb

er

of

Mo

nth

ly T

rid

em

Ax

le L

oa

ds

Figure 4 Monthly tridem axle load distribution or spectra for the base year for


For the simplistic M-E analysis procedure, the design values recommended for use by the

Michigan DOT were used in the design computations and checks because of the different

types of trucks typically used in Michigan, as compared to other agencies from traffic

data included in the LTPP database. Re-analyzing the Weighing-In-Motion (WIM) data

for selected Michigan sites was beyond the scope of work for this thickness design study.

3.2 Subsurface Investigations – Soil Support Design Value

The logs of sixty-nine 5-fott (1.5-meter) borings were provided to determine the types of

soils along this project. The soils along this portion of I-96 consist of varying thickness of

fill or topsoil over a low plasticity, firm silty clay.

The effective resilient modulus of the foundation soil is a design parameter required by

the 1993 AASHTO Design Guide and M-E design procedures. The resilient modulus is

determined from repeated load triaxial tests, and can have a significant impact on the

flexible pavement layer thickness. Resilient modulus tests were unavailable for the soils

along this roadway. The Michigan DOT used a design resilient modulus of 3,000 psi

(20,684 kPa) in the AASHTO design. This design resilient modulus is based on


6

Michigan’s experience and should be conservative for the existing foundation soil that

will not be removed during the reconstruction of this segment along I-96.

Repeated load resilient modulus tests of similar soils, however, are available in the LTPP

database for various sites in Michigan. Figure 5 shows the average test results for this

type of soil, which are similar to those estimated from correlations developed by Von

Quintus, et al.(4)

Thus, the repeated load resilient modulus test results shown in figure 5

were used to estimate the design resilient modulus for the foundation soil for both M-E

design procedures.

0

1

2

3

4

5

6

7

8

9

10

0 5 10

Cyclic Deviator Stress, psi

Re

silie

nt

Mo

du

lus

, k

si Confinement = 2 psi

Confinement = 4psi

Confinement = 6 psi

Figure 5 Average repeated load resilient modulus test results recovered from

the LTPP database for silty clay soils, similar to those encountered

along I-96.

The correlations noted above only represent a best-guessed value for design. The design

values used in the M-E design procedures are greater than the value suggested for use by

the Michigan DOT (3,000 psi or 20,684 kPa) in the AASHTO DARWin program. The

difference in these design resilient modulus values will be discussed in greater detail in a

latter section of this report.

To confirm the design resilient modulus values for the in place soils, however, it is

suggested that repeated load resilient modulus tests be performed in the laboratory on

undisturbed or re-compacted test specimens. If repeated load resilient modulus tests are

not possible, deflection basins can be measured along the existing roadway and the elastic

modulus back-calculated for the subgrade soils using the procedure used by Von Quintus

et al, for LTPP.(5,6)

If modulus values are back-calculated from deflection basins along I-


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96, they should be adjusted using the correction factors recommended by Von Quintus, et

al.(6)

Based on the boring logs provided, the subgrade soils encountered along the section of I-

96 are believed to have a frost susceptibility classification of moderate or medium using

the Corps of Engineers classification system (refer to figure 6).(7)

It is suggested that a

non-frost susceptible material be placed above the subgrade to minimize the potential for

frost heave over time. Thus, a minimum of 36 inches (914 mm) of non-frost susceptible

materials were included in the pavement cross-sections analyzed in this study.

Results from the subsurface investigations did not indicate ground water at the time of

drilling. Seasonal variation in ground water is expected for this area. Thus, subsurface

drains were assumed in the design computations for determining the required layer

thickness. It is understood that subsurface drains and a geotextile fabric-separator are

included in the planned reconstruction.

3.3 Non-Frost Susceptible Material

For this climatic area, the Michigan DOT requires that 36 inches (914 mm) of non-frost

susceptible material be placed above any frost-susceptible soil based on historical data

and experience. The thickness of non-frost susceptible material requirement was

assumed for this design study and not re-evaluated, as noted above.

Two unbound aggregate materials are available for use in the reconstruction of this

segment along I-96: a class IIA sand subbase and a 21AA-MOD crushed stone aggregate

base. Resilient modulus tests were completed and are available for similar materials from

the FHWA-LTPP database for test sections in Michigan. This laboratory data was used to

estimate the resilient modulus for each of these materials, similar to the method used to

develop Pavement Structural Design Study – A Simplified Catalog of Solutions.(2)

A

geotextile fabric should be used as a separator layer between the crushed aggregate base

and sand subbase.

Sand Subbase Material

It is understood that the existing sand material encountered in the borings along I-96 will

be replaced with Class IIA material for the flexible pavement design option. Resilient

modulus tests on the sand proposed for use were unavailable. However, repeated load

resilient modulus tests performed on materials classified as sand subbases were

previously extracted from the LTPP database.

Figures 17 to 20 in Appendix B graphically present the distribution of the resilient

modulus measured at specific stress states. It is important to note that the distributions

appear to be normal for those groups with a sufficient number of tests. This normal

distribution of resilient modulus values at specific stress states is also applicable to other

unbound materials that have a sufficient number of resilient modulus tests.


8

Table 2 summarizes the median resilient modulus values included in Appendix B for

sandy soils and sand subbase materials. As tabulated, the median resilient modulus for

the sand subbase material is about 18,500 psi (127,553 kPa) for all tests, as well as the

tests for samples recovered from only the LTPP sites located in Michigan.

Figure 6. Average rate of heave versus percentage finer than 0.02 mm for natural

soil gradations.(6)


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Figure 7 shows the average test results for a Class IIA sand subbase material in Michigan

that were extracted from the LTPP database. These average test results were used to

determine the design resilient modulus for both M-E design procedures.

Table 2 Median resilient modulus measured on the sand subbases and sand

subgrades recovered from all of the LTPP sites and from those sites

that are located in Michigan.

Median Resilient Modulus, psi (MPa)

(Refer to figures 17 to 20 in Appendix B) Material/

Layer

Stress State

All LTPP Sites LTPP Sites in Michigan

Sand

Subbase

Confinement = 10 psi

Cyclic Stress = 9 psi

18,400 (126.9)

(N=62)*

18,700 (128.9)

(N=10)

Sand

Subgrade

Confinement = 2.0 psi

Cyclic Stress = 1.8 psi

7,700 (53.1)

(N=440)

8,300 (57.2)

(N=7)

* N = number of resilient modulus tests within each group.

0

5

10

15

20

25

30

35

0 50 100 150

Bulk Stress, psi

Re

silie

nt

Mo

du

lus

, k

si

Confinement = 3 psi

Confinement = 5 psi




Figure 7 Average repeated load resilient modulus test results extracted from

the LTPP database for a sand subbase that is expected to be similar to

the material placed along I-96.


10

Crushed Stone Aggregate Base Material

The crushed stone aggregate base material planned for use along I-96 is a material that

meets the Michigan DOT’s specification for a 21 AA-MOD material. Table 3 lists the

gradation for this aggregate base material. The resilient modulus tests completed on

unbound aggregate base materials were extracted from the LTPP database for similar

aggregate base materials. However, no resilient modulus tests have been completed on

aggregate base materials that have a similar gradation to the one listed in table 3. Most of

the base material tested within the LTPP program represents a more dense material.

Figure 8 shows the average test results from repeated load resilient modulus tests for

aggregate base materials that are as close as possible – but have slightly more material

passing the smaller sieve sizes. These average values included in figure 8 were used in

the study for the crushed stone aggregate base material.

Table 3 Gradation requirements for the 21 AA-MOD crushed aggregate base

planned for use along I-96.

Sieve Size 37.5 mm 25.0 mm 12.5 mm 2.36 mm 0.60 mm 0.075 mm

Percent

Passing, % 100 80-100 40-70 15-35 5-20 <8

0

5

10

15

20

25

30

35

40

0 50 100 150

Bulk Stress, psi

Re

silie

nt

Mo

du

lus

, k

si

Confinement = 3 psi

Confinement = 5 psi




Figure 8 Average repeated load resilient modulus test results extracted from

the LTPP database for a 21AA crushed aggregate base.


11

3.4 Hot Mix Asphalt Mixtures

Three hot mix asphalt (HMA) mixtures are planned for use along I-96; an HMA wearing

course, an HMA leveling course, and an HMA base course (refer to figure 1). The elastic

modulus of the HMA is an input parameter for both the M-E analysis methods used in

this design study. Dynamic modulus tests are unavailable for the mixtures planned for

use along I-96, and are not included in the LTPP database. Thus, the Witczak dynamic

modulus regression equation embedded in the new M-E Pavement Design Guide was

used to calculate the modulus for each HMA mixture.

Figures 9 to 11 show the average modulus at the mid-depth of each HMA layer. These

monthly values at various depths were used in the new M-E Pavement Design Guide

software. However, an equivalent annual modulus for each layer was used with the

simplistic M-E analysis method. These resulting equivalent annual modulus values are

provided in Appendix C.

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15

Month of Year

Dyn

am

ic M

od

ulu

s, ksi

Figure 9 Monthly average dynamic modulus values calculated at the mid-depth

of the HMA wearing surface and leveling layers.

The HMA mixtures are assumed to have minimum fracture characteristics. Figure 12

graphically illustrates the minimum tensile strains at failure as a function of the resilient

modulus measured using indirect tensile testing methods in accordance with the

procedure recommended by Von Quintus, et al.(12)

The fatigue cracking criteria used in

the design study corresponds to the relationship in figure 12. The evaluation of fatigue

cracking for the HMA layers was completed in accordance with the steps outlined by

Von Quintus, et al., and Von Quintus and Killingsworth.(10,12)


12

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15

Month of Year

Dyn

am

ic M

odu

lus, ksi


of the upper portion of the HMA base layer.

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15

Month of Year

Dyn

am

ic M

od

ulu

s, ksi


of the lower portion of the HMA base layer.


13

1

10

100

10 100 1000 10000

Total Resilient Modulus, psi

Ten

sile S

train

at

Failu

re, m

ils/in

.

Figure 12 Relationship between minimum tensile failure strains and indirect

tensile resilient modulus.(12)

3.5 Subsurface Drainage System

A subsurface drainage system was included in the proposed design for I-96. The

subsurface drainage system ensures that the non-frost susceptible sand subbase and soils

will not become saturated for extended periods of time. This recommendation and design

feature is based on information recovered from boring logs and reported by Michigan

DOT for the supporting soils in adjacent areas along I-96.

4. Mechanistic-Empirical Thickness Design-Evaluation Method

Two M-E analysis procedures were used to evaluate the design resulting from the

AASHTO DARWin program (refer to figure 1). One is defined as the simplistic M-E

procedure and the other is the new M-E Pavement Design Guide. Appendix C includes

the response computations for the simplistic M-E procedure, while Appendix D provides

the results of the evaualtion using the new M-E Pavement Design Guide software. This

section of the report provides a summary of the results from the simplistic and new M-E

analysis procedures.

The structural deterioration of flexible pavements is associated with cracking of the HMA

surface, and/or development of ruts in the wheel path. The methodology used in this


14

study, applies the cumulative damage concept in the prediction of these two modes of

distress. Use of the cumulative damage concept permits accounting, in a rational manner,

for damage caused by each load application.

Seasonal and other variations in material properties and modulus of each layer with

different loads can be considered in these predictions of damage. Evaluations of design

life for candidate pavement structures are based on computations of damage caused by

each truck type and load (or an 18-kip ESAL) for different seasons of the year, and

summing the results to obtain the total damage to the pavement structure. For this design

study, however, dynamic modulus tests results were unavailable for all HMA mixtures

planned for use along I-96. As noted above, the dynamic modulus for the HMA mixtures

were calculated using the Witczak regression equation included in the new M-E

Pavement Design Guide software. An equivalent annual modulus for similar HMA

mixtures was used in the design study. The equivalent annual modulus values are

included in Appendix C.

4.1 Pavement Structural Evaluation Assumptions

The pavement layer thickness and material types were based on mechanistic-empirical

techniques, in accordance with the following assumptions and design features.

• The pavement structural response model used to calculate pavement responses

for the simplistic M-E analysis method was based on elastic layer theory -

EVERSTRS.

• The proposed pavement structure was evaluated using the design criteria for

fatigue cracking (limiting the tensile strain at the bottom of the HMA layers),

HMA rutting (limiting the vertical strain at the mid-depth of each HMA

layer), and subgrade distortion (limiting the vertical strain at the top of the

foundation soil).

• Structural design life = 20 years.

• Tire load = 4,500 lbs. (20 kN) per tire.

• Tire pressure = 120 psi (827 kPa).

• Sand Subbase; Assumed to be non-frost susceptible and determined from

repeated load resilient modulus tests included in the LTPP database, figure 7;

Poisson’s ratio = 0.40.

• Aggregate Base (21AA-MOD); Determined from repeated load resilient

modulus tests included in the LTPP database, figure 8; Poisson’s ratio = 0.35.

• The combined equivalent annual elastic layer modulus for the HMA surface,

leveling, and base mixtures = 892,000 psi (127.6 MPa) for the simplistic M-E

analysis method, refer to Appendix C; Poisson’s ratio = 0.30. For the new M-

E Pavement Design Guide, the dynamic modulus default values for a

Superpave mix with a PG 70-22 asphalt was used (figures 9-11). The asphalt

grades included as defaults in the new M-E Design Guide software are only

for the standard grades.


15

4.2 Evaluation Criteria

The objective of this study was to evaluate the flexible pavement structure shown in

figure 1 using M-E criteria over two analysis periods: 20 and 40 years. The failure of a

pavement system under the cumulative damage concept is assumed to occur when the

damage index reaches a fixed amount, generally 1.0. It should be understood that a

damage index of 1.0 does not necessarily imply a functional failure, but is instead that

level of damage selected as sufficient to warrant maintenance and/or rehabilitation.

Failure of flexible pavements is defined as alligator cracking over 10 to 20 percent of the

area subjected to wheels or one-half inch (12.7 mm) of foundation rutting.

For this study, a damage index of 1.0 means the pavement has been subjected to a

sufficient number of wheel loads (Nf) to cause 10 to 20 percent alligator cracking of

moderate to high severity or 0.5 inches (12.7 mm) of foundation distortion. In addition, a

value of 0.40 inches (10 mm) of distortion (rutting, ∆HMA) in the HMA layers was also

used in the evaluation. These values of 10 to 20 percent cracking and 0.5 inches (12.7

mm) of foundation distortion were selected, because previous studies of in-service

pavements have indicated that these levels will usually trigger some type of pavement

rehabilitation.

4.3 Simplistic M-E Analysis Method

Fatigue Cracking Evaluation

Two fatigue cracking models were used with the simplistic M-E analysis method.

Equation 1 and figure 13 were used to determine the allowable number of load

applications for fatigue cracking analysis of the pavement structure.

( ) ( )( ) ( ) 854.0291.300432.0

−−= ECFatigueN tf ε (1)

Where:

( )MC 10= (2)

−

+= 69.084.4

bea

be

VV

VM (3)

εt = Tensile strain at the bottom of the HMA layer, in./in.

E = HMA elastic or dynamic modulus, psi.

C = Correction factor to account for volumetric properties

Vbe = Percent effective asphalt content by volume in HMA mixture, %

Va = Percent air voids in the HMA mixture, %

Equation 1 is based on 20 percent fatigue cracking, and is the equation embedded in the

new M-E Pavement Design Guide software, but without the global calibration factors.

The global calibration factors were not used because they were determined based on the

cracking predictions using the modulus values of each layer within specific time intervals

and seasons. The simplistic M-E method uses equivalent annual modulus values for each


16

layer, which are presented and discussed in Appendix C. Figure 13 presents the

allowable number of load applications for 10 percent cracking. Table 4 summarizes the

allowable or permissible tensile strain at the bottom of the HMA layer for both the 20 and

40-year traffic levels using both fatigue cracking relationships.

The tensile strain at the bottom of the HMA layers was computed with EVERSTRS for

the AASHTO design, which is also included in table 4 (refer to Appendix C). As shown,

the computed tensile strain is less than the permissible HMA tensile strains for both

fatigue cracking models. In fact, the computed tensile strain of 49.7 micro-strains is

below the assumed endurance limit for HMA. Typical values being used for the

endurance limit are in the range of 65 to 75 micro-strains. Thus, fatigue cracking should

not be a problem for the proposed structure.

Figure 13 Relationship between HMA tensile strain and allowable wheel load

applications for the alligator cracking failure criteria.(8)

Distortion Evaluation – Unbound Layers

Equation 4 and figure 14 were used to determine the allowable number of load

applications for distortion analyses of the unbound layers in the pavement structure.

( ) ( ) ( )( ) 082.4955.01110259.1−−

= SoilvRf MxDistortionN ε (4)

0.0001

0.0010

0.0100

1,000 10,000 100,000 1,000,000 10,000,000

Wheel Load Applications

Asp

halt

Co

ncre

te T

en

sile S

train

, in

/in

1,000,000 psi

600,000 psi

300,000 psi

100,000 psi

Asphalt Concrete Modulus


17

Where:

MR = Resilient modulus of the foundation soil, psi.

εv(Soil) = Vertical strain at the top of the foundation soil, in./in.

Table 4 summarizes the allowable or permissible vertical strain at the top of the sand

subbase and foundation soil for both the 20 and 40-year traffic levels. The vertical strains

at the top of the sand subbase and foundation soil were computed with EVERSTRS for

the AASHTO design, which are also included in table 4 (refer to Appendix C). As

shown, the computed vertical strains are significantly less than the permissible vertical

strains for both layers. Thus, distortion in the unbound layers should not be a problem for

the proposed structure.

Table 4 Limiting criteria that were used to evaluate the design layer thickness

(refer to figure 1) for a 20 and 40-year analysis periods.

Limiting or Permissible

Values Design Criteria

20-Year

Analysis

40-Year

Analysis

Computed

Responses

(See Note 1)

Design 80-kN (18-kip) ESALs 22,694,400 56,000,000 ---

Equation 1;

20% Cracking 0.000100 0.000075 Tensile strain at the

bottom of the HMA

layers, in./in. Figure 13;

10% Cracking 0.000070 0.000053

0.0000497

Vertical Strain in the HMA layers,

in./in. 0.000091 0.000068 0.00009196*

Vertical strain at the top of the non-

frost susceptible sand material, in/in. 0.000284 0.000227 0.0000993

Vertical strain at the top of the

foundation soil, in./in. 0.000235 0.000187 0.0000889

Permissible maximum surface

deflection, in. 0.0175 0.0158 0.0108

Unbound layer modulus ratios Material and Thickness

Dependent, but <3.0 ---

Note 1: Pavement responses determined at the equivalent annual or summer modulus values for the

standard 18-kip ESAL. The pavement responses were computed with the EVERSTRS elastic layered

program (refer to Appendix C).

*Note 2: Those cells shaded or highlighted with bold numbers indicate the computed values that exceed

the permissible values listed.


18

Figure 14 Relationship between subgrade vertical strain and allowable wheel

load applications for the foundation deformation failure criteria.(9)

Rutting Evaluation – HMA Layers

Equation 5 was used to calculate the expected rutting within the HMA layers (∆HMA) of

the pavement structure and the permissible vertical strain in the HMA so that the rut

depth in the HMA layers does not exceed 0.40 inches (10 mm).

( ) ( ) ( ) ( ) ( ) ( )( )( )HMAHMAvfabeHMA tcNVVTx ε4289.05213.00057.15896.271037.5 −

=∆ (5)

Where:

T = Mid-depth temperature of the HMA layer thickness increment, in.

εv(HMA) = Vertical strain at the mid-depth of the HMA layer thickness increment,

in./in.

cf = Confinement factor

tHMA = Thickness of the HMA increment, inches

Table 4 summarizes the allowable or permissible vertical strain at the mid-depth of the

HMA surface layers for both the 20 and 40-year traffic levels. The vertical strains at the

mid-depth of the HMA surface layers were computed with EVERSTRS for the AASHTO

design, which are also included in table 4 (refer to Appendix C). As shown, the

0.0001

0.0010

0.0100

1,000 10,000 100,000 1,000,000 10,000,000

W heel Load Applications

Su

bg

rad

e V

ert

ica

l C

om

pre

ss

ive

Str

ain

, in

/in

20,000 psi

10,000 psi

6,000 psi

3,000 psi

2,000 psi

Subgrade Modulus


19

computed vertical strain is greater than the permissible vertical strain. The rutting

calculated with equation 5 is 0.48 inches (12 mm) for the 20-year traffic and 0.70 inches

(18 mm) for the 40-year traffic. Thus, the simplistic M-E method suggests that rutting in

the HMA layers is expected to require the pavement to be rehabilitated within the

analysis period.

Other Evaluation Criteria

Two other criteria were used for the simplistic M-E thickness design check or evaluation.

One is based on limiting the maximum surface deflection and the other is based on

limiting the modulus ratio between two adjacent unbound pavement layers (figure 15).

The long-term in place modulus of unbound base and subbase layers are dependent on the

modulus of the supporting layer because of potential de-compaction in the lower portion

of these layers. The Corp of Engineers developed criteria to limit the modulus of

unbound aggregate layers based on the thickness of that layer and the modulus of the

supporting layer.(9)

This limiting modulus ratio criteria (figure 15) was used in

determining the limiting modulus of the unbound aggregate base and subbase layers. The

elastic layer modulus used in the design computations with EVERSTRS for the unbound

layers are less than those that would result from using figure 15, because the actual stress

sensitivity was used in determining those values.

The permissible surface deflection is listed in table 4 for the two traffic levels or analysis

periods. This permissible deflection criteria has been used by Von Quintus and

Killingsworth and others in analyzing the performance of in-service pavements.(10,11)

Table 4 also includes the maximum surface deflection computed with EVERSTRS (refer

to Appendix C). As shown, the computed value is less than the permissible value.

4.4 New M-E Pavement Design Guide Software

The new M-E Pavement Design Guide software was used to evaluate the proposed

pavement cross section designed using the AASHTO DARWin program. The inputs

used in the program were the best available data and the global default values were used

when insufficient data were available. Appendix D includes a summary of the inputs

used and predicted distresses over time. A 30-year analysis period was used in the

problem rather than 40 years, because the program became unstable above 30 years.

In summary, the proposed flexible pavement and HMA mixtures are not expected to

exhibit significant levels of distress, with the exception of rutting. The new M-E

Pavement Design Guide software predicts greater levels of rutting in the unbound

materials, especially in the foundation soil. One reason for this result is that most of the

sites used in the calibration process for the new software have resilient modulus values

for the subgrade and unbound base layers much greater than those used in this design-

evaluation study.


20

Figure 15 Limiting modulus criteria of unbound aggregate base and subbase

layers.(9)

1 10 100

Modulus of Layer n + 1, 10 psi

1

10

100M

odulu

s o

f Layer

n, 10 p

si

3

BASE COURSES

(Meter = Inch x .0254) SUBBASE COURSES

THIC

KNESS

10"

6"

4"

4"

6"

5"7"

8"

105 psi = 698 MPa


21

5. Summary of Evaluations

Table 5 provides a summary of all distresses predicted with the different M-E analysis

methods used in this study. In summary, the pavement design cross section proposed for

the reconstruction of I-96 is adequate relative to cracking. The one concern is with

rutting and distortion.

The new M-E Pavement Design Guide software predicts most of the distortion in the

unbound layers and foundation soil, while the simplistic M-E analysis method predicts

that most of the rutting will occur in the HMA layers. As noted in the previous section, it

is believed that the rutting is being over predicted in the foundation soil with 14 inches of

HMA and 16 inches of a crushed aggregate base. In addition, this segment of I-96 has a

much higher traffic level than most of the LTPP sections that were used in the calibration

of the new M-E Pavement Design Guide have much less traffic. For this reason, it is

believed that most of the rutting will be in the HMA mixtures.

Table 5 Summary of distresses predicted for the two analysis periods using the

two M-E analysis methods.

Simplistic M-E Method New M-E Pavement

Design Guide Software Predicted Distress

20-Year 40-Year 20-Year 40-Year

Damage

Index

0.324

(0.101)*

0.801

(0.249)* 0.028 0.047

Fatigue

Cracking Area

Cracking, %

2

(0)*

6

(1)* 8.4 11.9

Top-Down Cracking, ft./mi. NA NA 267 274

Thermal Cracking, ft./mi. NA NA 40 211

PG 70-22 0.48 0.70 0.77 0.86 Total Rutting,

inches PG 76-22 0.36 0.54 NA NA

PG 70-22 0.48 0.70 0.21 0.26 Layer Rutting

or Distortion,

inches Unbound

Layers Minimal Minimal 0.56 0.60

IRI, in./mi. NA NA 120 134 *Note 1: The values in () for fatigue cracking are for the predictions using figure 13, while the

other fatigue cracking numbers are based on equation 1.

Note 2: The cells that are shaded or highlighted in the table exceed the allowable or permissible

distress magnitudes at the end of each analysis period.

An additional structure was analyzed to reduce the rutting in the HMA layers. The only

difference between the proposed AASHTO-designed flexible pavement and other

structure is that a PG 76-22 was included in the top two HMA layers (wearing surface

and leveling course). The comparison of the predicted rutting for the two asphalts is


22

shown in figure 16 and included in table 5. Using the stiffer asphalt will reduce rutting to

an acceptable level, even for the 40-year analysis period.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 10 20 30 40 50

Age, Years

Ru

t D

ep

th, in

ch

es

PG 76-22 PG 70-22

Figure 16 Comparison of predicted rutting for HMA mixtures with a PG 70-22

and a PG 76-22.

As shown in figure 1, a PG 70-22 asphalt is planned for use in the top two HMA layers.

Whether the dynamic modulus regression equation will adequately estimate the stiffness

values for the PG 70-22P mixtures is questionable. Whether a PG 70-22P or PG 76-22 is

used should be defined based on asphalt or mixture modulus testing or some type of

torture test to ensure that the HMA mixtures will be resistant to rutting. Without any

additional mixture testing, it is suggested that a PG 76-22 asphalt be included in the top

two mixtures. In addition, it should be confirmed that the pavement materials meet or

exceed the assumptions used in design. It is also recommended that sufficient testing be

completed during construction to ensure that the design assumptions are satisfied prior to

construction.

6. Limitations

All work performed under this study was conducted in accordance with generally

accepted pavement engineering practices using data and project information provided by

the Mr. Curtis Bleech. No other warranty, express or implied, is made. The generalized


23

pavement thickness design recommendations presented herein were based upon the

assumed subsurface and material conditions identified in the report. Sufficient testing

should be completed during construction for quality control purposes and to confirm the

design values assumed for this design study.

7. References

1. AASHTO, 1993 AASHTO Design Guide for Pavement Structures, American

Association of State Highway and Transportation Officials, 1993.

2. Von Quintus, Harold L., Pavement Structural Design Study – A Simplified Catalog of

Solutions, Report No. 3065, Fugro-BRE, Inc. December 2001.

3. NCHRP 1-37A, Mechanistic-Empirical Design Method for the Structural Design of

New and Rehabilitated Pavement Structures, Final Report for NCHRP 1-37A,

National Cooperative Highway Research Program, Washington, DC, 2004.

4. Von Quintus, Harold and Amber Yau, Evaluation of Resilient Modulus Test Data in

LTPP Database, Report No. FHWA/RD-01-158, Federal Highway Administration,

Office of Infrastructure Research and Development, Washington, DC, 2001.

5. Von Quintus, Harold and Amy Simpson, Documentation of the Back-Calculation o f

Layer Parameters for LTPP Test Sections, Volume II: Layered Elastic Analysis for

Flexible and Rigid Pavements, Final Report LTPP DATA, Work Order 9, Task 2

Contract No. DTFH61-96-C-00003, Federal Highway Administration, U.S.

Department of Transportation, January 1999.

6. Von Quintus, Harold and Brian Killingsworth, Design Pamphlet for the

Backcalculation of Pavement Layer Moduli, Publication No. FHWA-RD-97-076,

Federal Highway Administration, Washington, D.C., June 1997.

7. Soils and Geology – Pavement Design for Frost Conditions, TM5-818-2, Department

of the Army Technical Manual, Headquarters, Department of the Army, July 1965.

8. Finn, F.N., K. Nair, C. Monismith, Minimizing Premature Cracking of Asphalt

Concrete Pavements, NCHRP Report No. 195, National Cooperative Highway

Research Program, National Research Council, Washington, DC, June 1973.

9. Barker, W. R. and W. N. Brabston, Development of a Structural Design Procedure

for Flexible Airport Pavements, FAA Report No. FAA-RD-74-199, U.S. Army

Engineer Waterways Experiment Station, Federal Aviation Administration,

September 1975.


24

10. Von Quintus, H. L. and Brian Killingsworth, Analyses Relating to Pavement Material

Characterizations and Their Effects on Pavement Performance, Publication No.

FHWA-RD-97-085, Federal Highway Administration, January 1998.

11. Rauhut, J.B. R.L. Lytton, and M.I. Darter, Pavement Damage Functions for Cost

Allocation, Volume 1: Damage Functions and Load Equivalence Factors, Publication

No. FHWA/RD-84-018, Federal Highway Administration, Washington, DC, 1984.

12. Von Quintus, H.L., J.A. Scherocman, C.S. Hughes and T.W. Kennedy, Asphalt-

Aggregate Mixture Analysis System-AAMAS, NCHRP Report No. 338, National

Cooperative Highway Research Program, National Research Council, Washington,

DC, March 1991.


25

Appendix A

Summary of Truck Traffic Equivalent Single Axle Load Applications

Computed for the Base Year 2005

Appendix A includes a copy of the spreadsheet used to compute the number of 80-kN

(18-kip) equivalent single axle loads for the base year using the default distributions that

are included in the new M-E Pavement Design Guide for an urban freeway similar to I-

96.

As shown on the attached spreadsheet, the total number of annual ESALs for 2005 is

4,411,425 for both directions. Using a directional distribution factor of 0.56 and a lane

distribution factor of 0.70, the total number of annual ESALs in the design lane is

1,729,279. The average truck equivalency factor for this truck traffic stream is 1.259

ESAL per truck application.


26


27


28


29


30


31


32

Appendix B Summary of Repeated Load Resilient Modulus Tests Extracted from

the LTPP Database for the Michigan Sites.

Distribution of Average resilient Modulus for GSGB (Sand).

RES_MOD_AVG

50

100

150

200

250

Quantiles

maximum

quartile

median

quartile

minimum

100.0%

99.5%

97.5%

90.0%

75.0%

50.0%

25.0%

10.0%

2.5%

0.5%

0.0%

226.00

226.00

200.12

151.70

138.00

127.00

112.00

103.30

73.72

72.00

72.00

Moments

Mean

Std Dev

Std Error Mean

Upper 95% Mean

Lower 95% Mean

N

Sum Weights

126.7581

24.4612

3.1066

132.9700

120.5461

62.0000

62.0000

Figure 17 Resilient modulus (in MPa) measured on sand base and subbase

materials recovered from all sites in the LTPP program for a

confining pressure of 10 psi (69 kPa) and a cyclic stress of 9 psi

(62kPa). The resilient modulus values given above are in MPa.


33

Distribution of Average resilient Modulus for GSGB (Sand) for Michigan sites.

RES_MOD_AVG

100

120

140

160

180

200

Quantiles

maximum

quartile

median

quartile

minimum

100.0%

99.5%

97.5%

90.0%

75.0%

50.0%

25.0%

10.0%

2.5%

0.5%

0.0%

181.00

181.00

181.00

178.10

143.75

129.00

115.75

114.10

114.00

114.00

114.00

Moments

Mean

Std Dev

Std Error Mean

Upper 95% Mean

Lower 95% Mean

N

Sum Weights

133.2000

21.1019

6.6730

148.2955

118.1045

10.0000

10.0000

Figure 18 Resilient modulus (in MPa) measured on sand base and subbase

materials recovered from all Michigan sites included in the LTPP

program for a confining pressure of 10 psi (69 kPa) and a cyclic stress

of 9 psi (62 kPa). The resilient modulus values given above are in

MPa.


34

Distribution of Average resilient Modulus Subgrade Sand.

RES_MOD_AVG

100

200

Quantiles

maximum

quartile

median

quartile

minimum

100.0%

99.5%

97.5%

90.0%

75.0%

50.0%

25.0%

10.0%

2.5%

0.5%

0.0%

191.00

147.36

111.87

84.00

67.00

53.00

43.00

36.00

28.00

23.00

18.00

Moments

Mean

Std Dev

Std Error Mean

Upper 95% Mean

Lower 95% Mean

N

Sum Weights

57.6341

21.3246

1.0166

59.6321

55.6360

440.0000

440.0000

Figure 19 Resilient modulus (in MPa) measured on sand recovered from the

subgrade at all sites in the LTPP program for a confining pressure of

2.0 psi (13.8 kPa) and a cyclic stress of 1.8 psi (12.4 kPa). The resilient

modulus values given above are in MPa.


35

Distribution of Average resilient Modulus for Sugrade Sand for Michigan sites.

RES_MOD_AVG

50

100

150

200

Quantiles

maximum

quartile

median

quartile

minimum

100.0%

99.5%

97.5%

90.0%

75.0%

50.0%

25.0%

10.0%

2.5%

0.5%

0.0%

191.00

191.00

191.00

191.00

63.00

57.00

50.00

42.00

42.00

42.00

42.00

Moments

Mean

Std Dev

Std Error Mean

Upper 95% Mean

Lower 95% Mean

N

Sum Weights

73.4286

52.3477

19.7856

121.8422

25.0150

7.0000

7.0000

Figure 20 Resilient modulus (in MPa) measured on sand recovered from the

subgrade at all Michigan sites included in the LTPP program for a

confining pressure of 2.0 psi (13.8 kPa) and a cyclic stress of 1.8 psi

(12.4 kPa). The resilient modulus values given above are in MPa.


36

Appendix C Layer Properties and Pavement Responses Computed for the I-96

Design Cross Section

Appendix C includes a summary of the methods used to determine the elastic modulus

values for each layer and a copy of the pavement responses that were used to evaluate the

pavement structure. These responses were calculated with EVERSTRS for the standard

design axle load – 18-kip single axle load.

C.1 HMA Modulus Determination

As noted in the report, the dynamic modulus regression equation was used to estimate the

average modulus of each HMA mixture for each month of an average year. The first part

of Appendix C includes the spreadsheet used to determine the monthly modulus values

and the equivalent annual layer modulus for the HMA mixtures used in the fatigue

cracking analysis. For the rutting analysis and predictions made with the simplistic M-E

method, the elastic modulus for the three summer months was used.


37


38

C.2 Unbound Layer Modulus Determination

The second part of Appendix C includes a summary of the procedure and responses used

to determine the resilient modulus for each unbound layer. In other words, select an

elastic modulus for the unbound materials and soils to ensure that the theory

(EVERSTRS) and laboratory provide consistent values at the same stress state for use in

the fatigue analysis.

One of the important steps in this process is to include the at-rest stresses with those

computed from EVERSTRS. Table 6 provides a summary of the information and data

that were used to compute the overburden pressures and at-rest stresses in each unbound

layer.

Table 6 Data used to calculate the overburden pressure and at-rest stresses in

each unbound layer of the design cross section (refer to figure 1).

Layer/Material Type Dry Density,

pcf

Moisture

Content, %

At-Rest Earth Pressure

Coefficient, ko

HMA; average of all three

layers 150 --- ---

21 AA-MOD Crushed

Aggregate Base 130 7.0 0.9

Class II-A Sand Subbase 136 7.0 0.9

Low Plasticity, Firm Silty

Clay 116 13.0 0.5

Table 7 summarizes the EVERSTRS computations from two iterations of using trial

elastic modulus values for each unbound layer. The two iterations demonstrate the need

to check the values used in the elastic layer program to ensure that the theory and

laboratory values provide consistent results. As summarized in table 7, the first iteration

used the design resilient modulus suggested for use by the Michigan DOT and the

maximum layer modulus ratio to estimate the elastic modulus of all other unbound layers

(refer to figure 15). The trial or “guessed” resilient modulus values are not consistent

with the values that would be measured in the laboratory from repeated load tests (figures

5,7, and8). However, the modulus values used in the second iteration are, for all practical

purposes the same values that would be measured in the laboratory at the same stress

states. The values from the second iteration were used in the fatigue cracking analysis.


39

Table 7 Comparison of the trial elastic layer modulus used in EVERSTRS with those measured from repeated load

resilient modulus tests in the laboratory at the same stress state.

At-Rest Stress @ ¼

Layer Depth, psi

Stresses Computed w/EVERSTRS @

¼ Layer Depth, psi Total Stress State, psi

Iteration No. &

Unbound Layer

Trial E-

Value, ksi ZZ

XX &

YY ZZ XX YY

Confining

Stress

Deviator

Stress

Bulk

Stress

Lab E-

Value, ksi

Silty Clay* 3 -4.55 -2.28 -0.30 -0.04 -0.04 2.32 2.53 --- 5.1 Sand Subbase 9 -2.68 -2.41 -0.50 0.37 0.39 2.02 --- 7.24 6.8 1

Aggregate Base 20 -1.54 -1.39 -1.21 0.42 0.51 0.88 --- 4.60 6.5

Silty Clay* 5.2 -4.55 -2.28 -0.41 -0.07 -0.07 2.69 2.61 --- 5.2 Sand Subbase 7.0 -2.68 -2.41 -0.64 0.02 0.04 2.37 --- 8.08 7.2 2

Aggregate Base 7.5 -1.54 -1.39 -0.97 -0.11 -0.07 1.46 --- 5.47 7.5

*NOTE: The stress state was determined at the ¼ depth within each unbound layer, with the exception for the foundation or subgrade soils. The stress state was

determined 18-inches into the subgrade. These depths are consistent with the values recommended for use by Von Quintus, et al. (10)

The at-rest stresses were

computed using the information and data included in table 6.


40

C.3 EVERSTRS Output for Fatigue Cracking Analyses

The following is a summary of the output from the EVERSTRS program for the design

cross section using the layer modulus values determined in the previous section of

Appendix C. The other pavement responses are also included in this ouput for

determining the damage index for fatigue cracking and foundation distortion, and

whether the design cross section will be provide adequate performance over the two

analysis periods. These responses are based on equivalent annual modulus values.

CLayered Elastic Analysis by EverStress for Windows

Title: Michigan I-96 Reconstruction No of Layers: 5 No of Loads: 2 No of X-Y Evaluation Points: 2

Layer Poisson's Thickness Moduli(1)

* Ratio (in) (ksi)

1 0.3 14 892

2 0.35 16 7.5

3 0.35 8 7

4 0.45 240 5.2

5 0.4 * 50

Load No X-Position Y-Position Load Pressure Radius

* (in) (in) (lbf) (psi) (in)

1 0 0 4500 120 3.455

2 13 0 4500 120 3.455 Location No: 1 X-Position (in): .000 Y-Position (in): .000

cNormal Stresses

Z-Position Layer Sxx Syy Szz Syz Sxz Sxy

(in) * (psi) (psi) (psi) (psi) (psi) (psi)

13.999 1 49.55 56.79 -1.15 0 0.13 0

18 2 -0.11 -0.07 -0.97 0 0.1 0

32 3 0.02 0.04 -0.64 0 0.05 0

38.1 4 -0.12 -0.11 -0.56 0 0.03 0

56 4 -0.07 -0.07 -0.41 0 0.02 0

cNormal Strains and Deflections

Z-Position Layer Exx Eyy Ezz Ux Uy Uz

(in) * (10^-6) (10^-6) (10^-6) (mils) (mils) (mils)

13.999 1 36.83 47.39 -37.06 -0.246 0 10.163

18 2 34.26 40.87 -121.13 -0.235 0 9.642

32 3 33.55 35.68 -94 -0.224 0 8.197

38.1 4 35.04 36.79 -87.08 -0.233 0 7.643

56 4 28.26 29.03 -67.77 -0.186 0 6.268

cPrincipal Stresses and Strains

Z-Position Layer S1 S2 S3 E1 E2 E3

(in) * (psi) (psi) (psi) (10^-6) (10^-6) (10^-6)

13.999 1 -1.15 49.55 56.79 -37.06 36.83 47.39

18 2 -0.98 -0.1 -0.07 -123.34 36.47 40.87

32 3 -0.64 0.03 0.04 -94.71 34.26 35.68

38.1 4 -0.56 -0.12 -0.11 -87.81 35.77 36.79

56 4 -0.41 -0.07 -0.07 -68.11 28.6 29.03


41

Location No: 2

X-Position (in): 6.500 Y-Position (in): .000

cNormal Stresses



13.999 1 51.24 59.38 -1.19 0 0 0

18 2 -0.1 -0.07 -1.01 0 0 0

32 3 0.03 0.04 -0.65 0 0 0

38.1 4 -0.12 -0.11 -0.57 0 0 0

56 4 -0.07 -0.07 -0.42 0 0 0



(in) * (10^-6) (10^-6) (10^-6) (mils) (mils) (mils)

13.999 1 37.87 49.74 -38.54 0 0 10.299

18 2 36.9 42.51 -126.58 0 0 9.756

32 3 34.99 36.22 -96.23 0 0 8.26

38.1 4 36.26 37.23 -88.89 0 0 7.695

56 4 28.82 29.22 -68.58 0 0 6.299



(in) * (psi) (psi) (psi) (10^-6) (10^-6) (10^-6)

13.999 1 -1.19 51.24 59.38 -38.54 37.87 49.74

18 2 -1.01 -0.1 -0.07 -126.58 36.9 42.51

32 3 -0.65 0.03 0.04 -96.23 34.99 36.22

38.1 4 -0.57 -0.12 -0.11 -88.89 36.26 37.23

56 4 -0.42 -0.07 -0.07 -68.58 28.82 29.22


42

C.4 EVERSTRS Output for HMA Rutting Analyses

The output from the EVERSTRS program summarized below was used to calculate the

expected rutting in the HMA layers using the average summer modulus values.

CLayered Elastic Analysis by EverStress for Windows

Title: Michigan I-96 Reconstruction No of Layers: 5 No of Loads: 2 No of X-Y Evaluation Points: 2

Layer Poisson's Thickness Moduli(1)

* Ratio (in) (ksi)

1 0.3 4 700

2 0.35 10 615

3 0.35 24 7.5

4 0.45 240 5.2

5 0.4 * 50

Load No X-Position Y-Position Load Pressure Radius

* (in) (in) (lbf) (psi) (in)

1 0 0 4500 120 3.455

2 13 0 4500 120 3.455 Location No: 1

X-Position (in): .000 Y-Position (in): .000

cNormal Stresses



1 1 -85.01 -89.89 -116.84 0 1.14 0

3 1 -28.04 -28.95 -82.96 0 3.21 0

5.2 2 -11.11 -9.67 -46.35 0 4.85 0

7.7 2 4.15 6.63 -22.69 0 5.49 0

11.5 2 27.58 31.48 -5.29 0 3.59 0



(in) * (10^-6) (10^-6) (10^-6) (mils) (mils) (mils)

1 1 -32.84 -41.9 -91.96 0.235 0 12.081

3 1 7.9 6.21 -94.09 0.134 0 11.881

5.2 2 13.82 16.98 -63.54 0.041 0 11.708

7.7 2 15.89 21.33 -43.02 -0.052 0 11.579

11.5 2 29.94 38.5 -42.21 -0.196 0 11.426



(in) * (psi) (psi) (psi) (10^-6) (10^-6) (10^-6)

1 1 -116.88 -89.89 -84.97 -92.03 -41.9 -32.77

3 1 -83.15 -28.95 -27.86 -94.44 6.21 8.25

5.2 2 -47.01 -10.45 -9.67 -64.98 15.26 16.98

7.7 2 -23.77 5.23 6.63 -45.4 18.26 21.33

11.5 2 -5.68 27.97 31.48 -43.06 30.79 38.5


43

Appendix D Analysis of the Proposed Pavement Design Cross Section for I-96 Using

the New M-E Pavement Design Guide Software

Appendix D includes a listing of the inputs used in the new M-E Pavement Design Guide

software. In addition, graphical summarizes of all predicted distresses follow the inputs.


44

Limit Reliability

65

170 90

2500 90

10 90

1000 90

0.35 90

0.6 90

9600

2

56

70

45

Project: I-96, Wayne County, Michigan

General Information Description:

This is an analysis of a flexible pavement design that

was completed using the 1993 AASHTO DARWin

procedure.

Design Life 30 years

Base/Subgrade construction: September, 2003

Pavement construction: September, 2003

Traffic open: October, 2003

Type of design Flexible

Analysis ParametersAnalysis type Probabilistic

Performance CriteriaInitial IRI (in/mi)

Terminal IRI (in/mi)

AC Surface Down Cracking (Long. Cracking) (ft/500):

AC Bottom Up Cracking (Alligator Cracking) (%):

AC Thermal Fracture (Transverse Cracking) (ft/mi):

Permanent Deformation (AC Only) (in):

Permanent Deformation (Total Pavement) (in):

Location: I-96; Wayne County, Michigan

Project ID: CS 82122

Section ID: M-39 to Schaefer Road

Principal Arterials - Interstate and Defense Routes

Date: 8/26/2004

Station/milepost format: Miles: 0.000

Station/milepost begin: 11.72

Station/milepost end: 12.05

Traffic direction: East bound

Default Input LevelDefault input level Level 3, Default and historical agency values.

Traffic Initial two-way aadtt:

Number of lanes in design direction:

Percent of trucks in design direction (%):

Percent of trucks in design lane (%):

Operational speed (mph):

Class 4 Class 5 Class 6 Class 7 Class 8 Class 9 Class 10 Class 11 Class 12 Class 13

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Traffic -- Volume Adjustment Factors

Monthly Adjustment Factors (Level 3, Default MAF)

Vehicle Class

Month

January

February

March

April

May

June

July

August

September

October

November

December


45

Midnight 1.2% Noon 3.5%

0.9% 1:00 am 0.6% 1:00 pm 4.2%

11.6% 2:00 am 0.5% 2:00 pm 6.1%

3.6% 3:00 am 0.5% 3:00 pm 7.3%

0.2% 4:00 am 0.6% 4:00 pm 7.1%

6.7% 5:00 am 2.3% 5:00 pm 9.8%

62.0% 6:00 am 8.0% 6:00 pm 6.4%

4.8% 7:00 am 7.9% 7:00 pm 4.0%

2.6% 8:00 am 7.4% 8:00 pm 3.0%

1.4% 9:00 am 4.5% 9:00 pm 2.8%

6.2% 10:00 am 3.9% 10:00 pm 2.3%

11:00 am 4.1% 11:00 pm 2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

2.0%

18

10

12

1.62 0.39 0.00 0.00

2.00 0.00 0.00 0.00

1.02 0.99 0.00 0.00

1.00 0.26 0.83 0.00

2.38 0.67 0.00 0.00

1.13 1.93 0.00 0.00

1.19 1.09 0.89 0.00

4.29 0.26 0.06 0.00

3.52 1.14 0.06 0.00

2.15 2.13 0.35 0.00

8.5

12

120

120

51.6

49.2

49.2

Vehicle Class Distribution Hourly truck traffic distribution

(Level 3, Default Distribution) by period beginning:

AADTT distribution by vehicle class

Class 4

Class 5

Class 6

Class 7

Class 8

Class 9

Class 10

Class 11

Class 12

Class 13

Traffic Growth Factor

Vehicle

Class

Growth

Rate

Growth

Function

Class 4 Compound

Class 5 Compound

Class 6 Compound

Class 7 Compound

Class 8 Compound

Class 9 Compound

Class 10 Compound

Class 11 Compound

Class 12 Compound

Class 13 Compound

Traffic -- Axle Load Distribution FactorsLevel 3: Default

Traffic -- General Traffic InputsMean wheel location (inches from the lane

marking):

Traffic wander standard deviation (in):

Design lane width (ft):

Number of Axles per Truck

Quad

Axle

Class 4

Class 5

Class 6

Vehicle

Class

Single

Axle

Tandem

Axle

Tridem

Axle

Class 7

Class 8

Class 9

Class 10

Class 11

Class 12

Class 13

Axle Configuration

Average axle width (edge-to-edge) outside

dimensions,ft):

Dual tire spacing (in):

Axle Configuration

Single Tire (psi):

Dual Tire (psi):

Average Axle Spacing

Tandem axle(psi):

Tridem axle(psi):

Quad axle(psi):


46

42.13

-83.21

628

10

Climate icm file:

Detroit-Michigan

Latitude (degrees.minutes)

Longitude (degrees.minutes)

Elevation (ft)

Depth of water table (ft)

-10 -16 -22 -28 -34 -40 -46

Structure--Design Features

Structure--Layers Layer 1 -- Asphalt concrete

Material type: Asphalt concrete

Layer thickness (in): 1.5

General Properties

General

Reference temperature (F°): 70

Volumetric Properties as Built

Effective binder content (%): 10.5

Air voids (%): 7.5

Total unit weight (pcf): 148

Poisson's ratio: 0.35 (predicted)

Parameter a: -1.63

Parameter b: 0.00000384

Thermal Properties

Thermal conductivity asphalt (BTU/hr-ft-F°): 0.67

Heat capacity asphalt (BTU/lb-F°): 0.23

Asphalt Mix

Cumulative % Retained 3/4 inch sieve: 0


Cumulative % Retained #4 sieve: 35

% Passing #200 sieve: 6.5

Asphalt Binder

Option: Superpave binder grading

A 10.2990 (correlated)

VTS: -3.4260 (correlated)

High temp.

°C

Low temperature, °C

46

52

58

64

70

76

82


47

-10 -16 -22 -28 -34 -40 -46

Layer 2 -- Asphalt concreteMaterial type: Asphalt concrete

Layer thickness (in): 2.5

General Properties

General




Air voids (%): 7.5



Parameter a: -1.63


Thermal Properties



Asphalt Mix




% Passing #200 sieve: 6

Asphalt Binder




High temp.

°C


46

52

58

64

70

76

82


48

-10 -16 -22 -28 -34 -40 -46

Layer 3 -- Asphalt concreteMaterial type: Asphalt concrete

Layer thickness (in): 10

General Properties

General




Air voids (%): 7.5



Parameter a: -1.63


Thermal Properties



Asphalt Mix




% Passing #200 sieve: 5.5

Asphalt Binder




High temp.

°C


46

52

58

64

70

76

82


49

Value

0.153

7.5

1.18

0.015

Value

4.86

7.5

0.365

17.5

Layer 4 -- Crushed gravelUnbound Material: Crushed gravel

Thickness(in): 16

Strength Properties

Input Level: Level 3

Analysis Type: ICM inputs (ICM Calculated Modulus)

Poisson's ratio: 0.35

Coefficient of lateral pressure,Ko: 0.5

Modulus (input) (psi): 7500

ICM Inputs

Gradation and Plasticity Index

Plasticity Index, PI: 0

Passing #200 sieve (%): 7


D60 (mm): 10

Calculated/Derived Parameters

Maximum dry unit weight (pcf): 130 (user input)

Specific gravity of solids, Gs: 2.65 (derived)

Saturated hydraulic conductivity (ft/hr): 302 (derived)

Optimum gravimetric water content (%): 7 (user input)

Calculated degree of saturation (%): 78 (calculated)

Soil water characteristic curve parameters: Default values

Parameters

a

b

c

Hr.

Layer 5 -- A-2-4Unbound Material: A-2-4

Thickness(in): 8

Strength Properties






ICM Inputs





D60 (mm): 0.1




Saturated hydraulic conductivity (ft/hr): 0.000866 (derived)


Calculated degree of saturation (%): 78 (calculated)


Parameters

a

b

c

Hr.


50

Value

57.5

1.18

0.648

2240

Value

57.5

1.18

0.648

2240

Layer 6 -- CLUnbound Material: CL

Thickness(in): 12

Strength Properties






ICM Inputs





D60 (mm): 0.1




Saturated hydraulic conductivity (ft/hr): 3.25e-005 (derived)


Calculated degree of saturation (%): 87.4 (calculated)


Parameters

a

b

c

Hr.

Layer 7 -- CLUnbound Material: CL

Thickness(in): Semi-infinite

Strength Properties






ICM Inputs





D60 (mm): 0.1




Saturated hydraulic conductivity (ft/hr): 3.25e-005 (derived)


Calculated degree of saturation (%): 87.4 (calculated)


Parameters

a

b

c

Hr.


51

0.00432

3.9492

1.281

-3.4488

1.5606

0.4791

5

1

1

1.673

1.35

7

3.5

0

1000

1

1

0

6000

1

1

0

1000

0.0463

0.00119

0.1834

0.00384

0.00736

0.00115

0.387

0.009995

0.000518

0.00235

18.36

Distress Model Calibration Settings - Flexible AC Fatigue Level 3 (Nationally calibrated values)

k1

k2

k3

AC Rutting Level 3 (Nationally calibrated values)

k1

k2

k3

Standard Deviation Total

Rutting (RUT):

0.1587*POWER(RUT,0.4579)+0.001

Thermal Fracture Level 3 (Nationally calibrated values)

k1

Std. Dev. (THERMAL): 0.2474 * THERMAL + 10.619

CSM Fatigue Level 3 (Nationally calibrated values)

k1

k2

Subgrade Rutting Level 3 (Nationally calibrated values)

Granular:

k1

Fine-grain:

k1

AC CrackingAC Top Down Cracking

C1 (top)

C2 (top)

C3 (top)

C4 (top)

Standard Deviation (TOP) 200 + 2300/(1+exp(1.072-2.1654*log(TOP+0.0001)))

AC Bottom Up Cracking

C1 (bottom)

C2 (bottom)

C3 (bottom)

C4 (bottom)

Standard Deviation (TOP) 32.7 + 995.1 /(1+exp(2-2*log(BOTTOM+0.0001)))

CSM Cracking

C1 (CSM)

C2 (CSM)

C3 (CSM)

C4 (CSM)

Standard Deviation (CSM) CTB*1

IRIIRI Flexible Pavements with GB

C1 (GB)

C2 (GB)

C3 (GB)

C4 (GB)

C5 (GB)

C6 (GB)

Std. Dev (GB)

IRI Flexible Pavements with ATB

C1 (ATB)

C2 (ATB)

C3 (ATB)

C4 (ATB)


52

The following graphs represent the distress predictions with the new M-E Pavement Design Guide software.

Surface Down Cracking - Longitudinal

0

300

600

900

1200

1500

1800

2100

2400

2700

3000

0 36 72 108 144 180 216 252 288 324 360 396

Pavement Age (month)

Longitudin

al C

rackin

g (ft

/mi)

Surface

Depth = 0.5"

Surface at Reliability

Design Limit

Bottom Up Cracking - Alligator

0

10

20

30

40

50

60

70

80

90

100

0 36 72 108 144 180 216 252 288 324 360 396


Allig

ato

r C

rackin

g (%

)

Maximum Cracking

Bottom Up Reliability

Maximum Cracking Limit


53

Thermal Cracking: Total Length Vs Time

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 36 72 108 144 180 216 252 288 324 360 396


Tota

l Length

(ft/m

i)

Thermal Crack Length

Crack Length at Reliability

Design Limit

Permanant Deformation: Rutting

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0 36 72 108 144 180 216 252 288 324 360 396


Rutt

ing D

epth

(in

) SubTotalAC

SubTotalBase

SubTotalSG

Total Rutting

TotalRutReliability

Total Rutting Design Limit

AC Rutting Design Value = 0.35

Total Rutting Design Limit = 0.6


54

IRI

0

20

40

60

80

100

120

140

160

180

200

0 36 72 108 144 180 216 252 288 324 360 396


IRI

(in

/mi) IRI

IRI at Reliability

Design Limit

pavement structural analysis of the design … pavement layer thickness and ... mr. curtis bleech...

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