module 2: climate input

Module 2: Climate Input

Jagannath Mallela, Michael I. Darter and Harold Von Quintus

Applied Research Associates, Inc. January 30, 2013

AASHTOWare Pavement ME Design Module 4: Materials and Design Inputs for New Pavement Design

Lesson 1: Material and Design Inputs for New Pavement Design Overview Pre-Requisite:

• Participant should have knowledge of the MEPDG material and design input requirements for various pavement types, as well as familiarity with the MEPEG input hierarchy concepts.

Objective: • Participant will know the different material inputs for new

designs and how to process them in DARWin-ME.

Module 4: Material & Design Inputs, New Designs Lesson 1: Overview

Material and Design Inputs for New Pavement Design

Outcomes: 1. Identify the material/layer properties needed as

inputs for all pavement materials. 2. Understand and know the representative values to

be entered for each material/layer property. 3. Capable to enter the material/layer properties for

different hierarchical input levels.


Topics 1. Asphalt Concrete Materials 2. Portland Cement Concrete

Materials 3. Chemically Stabilized Base

Materials 4. Unbound Layer and Subgrade

Materials Chapter 11


Material Hierarchical Input Levels Level 1:

• The average of laboratory/field test results from standard tests for the specific input property.

Level 2: • Properties are estimated from correlations with other

standard material tests.

Level 3: • Default values or best estimates of input parameter.


Material Inputs for ME Design Material/layer properties are well

defined. • AASHTO MEPDG Manual of Practice. • Do not assume same as AASHTO 93.

Properties are always “mean” values. Properties represent the

material/layer at the time of construction. • MEPDG procedure changes those values

over time throughout the design period.


Lesson 2: Asphalt Concrete Material Types Hot Mix Asphalt (HMA) – Neat and

Modified Binders • Dense Graded (Uniform and gap graded mixes) • Open Graded Asphalt • Asphalt Stabilized Base Mixes

Stone Matrix Asphalt (SMA) Warm Mix Asphalt Mixes with High RAP Contents Cold Mix Asphalt

Material property inputs are the same regardless of material type. Section 11.2

Module 4: Material & Design Inputs, New Designs Lesson 2: Asphalt Concrete Materials

Exception: Asphalt Treated Permeable layers should be simulated as a high quality aggregate

base layer with a constant modulus because of high air voids.


AC Layer Properties

Input levels 1, 2, & 3 are all the same.

AC Surface Shortwave Absorptivity: • Defines the amount of available solar energy absorbed by the

flexible pavement surface. • Use the ME Design default value of 0.85, unless calibrated to a

different value.

AC Layer Properties


Endurance Limit: ● Tensile strain below which no load-related fatigue damage occurs. ● False means it is not being used. ● One value is used regardless of temperature or stiffness. ● DO NOT USE because transfer function was calibrated assuming no

endurance limit.

AC Layer Properties



Layer Interface Friction: • Represents the bond between two AC adjacent layers. • Either full friction or no friction can be included in the analysis. • Recommended that full friction be used, except for forensic

investigation when it is found that a bond does not exist.

AC Layer Properties


AC Layer Properties

“1” – means full friction or bond between two layers. “0” means no friction or bond between two layers.


HMA Layers Input Categories:

1. Volumetric 2. Mechanical 3. Thermal


AC Mixture Volumetric Properties

● Use average values from previous construction season. ● The effective binder content is by volume and NOT by

weight. ● The unit weight and air voids are at construction and

NOT the mixture design or target values.



AC Poisson’s Ratio

● “False” means Poisson’s Ratio is a constant. ● “True” means the default values for Parameters A and B

are used to compute Poisson’s Ratio as a function of dynamic modulus.

Poisson’s Ratio is a mechanical property, but

included under Mixture Volumetric

category.

AC Poisson’s Ratio Predictive model from |E*|

testing

Typical values Temperature Dense graded Open graded < 0 °F 0.15 0.35

0 – 40 °F 0.20 0.35 40 – 70 °F 0.25 0.40

70 – 100 °F 0.35 0.40 100 – 130 °F 0.45 0.45

> 130 °F 0.48 0.45

)Ex..(acace

.. 6108436311

350150 −+−+

+=µ


Predictive model is recommended

for use.


AC Mechanical Properties

Mechanical Property Categories: ● Dynamic Modulus ● Asphalt Binder ● Indirect Tensile Strength ● Creep Compliance

Dynamic Modulus -Hierarchical Inputs Level Description

1 Dynamic Modulus (|E*|) Laboratory Testing & DSR Testing of Binder

2 |E*| Predictive Equation & DSR Testing of Binder

3 |E*| Predictive Equation & Recommended values of Binder Temperature-viscosity (A-VTS) relationship



Dynamic Modulus Input Level 3

Aggregate Inputs

Gradation of aggregate

blend.



Binder Related Inputs

● “False” means G* based dynamic modulus regression equation will not be used & E* based regression equation will be used.

● The E* based dynamic modulus regression was nationally calibrated, while the G* based regression equation was not.

● Reference Temperature for Master Curve.



Gradation of aggregate blend;

same as input level 3.

Aggregate Inputs




E* Regression Equation – same as for Input Level 3. Reference Temperature – same as for Input Level 3.



AASHTO TP 79




Binder inputs same as Input

Level 2.


Creep Compliance & IDT Strength

Creep Compliance & IDT Strength only needed for the Wearing Surface

Creep Compliance & IDT – Hierarchical Inputs Level Creep Compliance Indirect Tensile

Strength

1 Laboratory test at -4oF, 14oF and 32oF

Laboratory test at 14oF

2 Laboratory test at 14oF Extrapolated at -4oF and 32oF using power law

Laboratory test at 14oF

3 Regression equations (function of air voids, voids filled

with asphalt and binder viscosity)



Indirect Tensile Strength

● Input Level 3 – program calculates indirect tensile strength.

● Input Levels 1 & 2 – IDT strength: ● Test Protocol – AASHTO T 322 ● Test Temperature – 14 °F


Creep Compliance

● Input Level 3 – program calculates creep compliance values.

● Input Levels 1 and 2 – Creep compliance values measured in laboratory at specific temperatures using AASHTO T 322.

Creep Compliance Input Levels 1 & 2


Input Level 1 Input Level 2


Thermal Input Category

Use default values, unless transfer functions are recalibrated at other values.


Lesson 3: Chemically Stabilized Base

Materials

Cement Stabilized Base Lime-Fly Ash Stabilized Base Soil Cement Lime Stabilized Soil

Asphalt stabilized bases are considered asphalt concrete layers. Section 11.4

Module 4: Material & Design Inputs, New Designs Lesson 3: Chemically Stabilized Base Materials

Chemically Stabilized Materials

Input Categories: 1. General Properties 2. Strength Properties 3. Thermal Properties

Chemically Stabilized

Layer


General Input Category Input levels 1, 2, & 3

are the same.

Poisson’s Ratio: Used to calculated responses.

Recommended values in Manual of Practice.

Unit Weight: Used to determine other input values related to input level 3

values.


Strength Input Category ● Semi-Rigid Pavements ● Rigid Pavements


Asphalt Concrete


Chemically Stabilized Layer Location Asphalt Concrete

Chemically Stabilized Layer

Unbound Aggregate Layer

Subgrade or Embankment

Unbound Aggregate Layer (Cushion Layer)

Chemically Stabilized Layer

Subgrade or Embankment

Treat as a Semi-Rigid pavement and enter as a chemically

stabilized layer.

Treat as a flexible pavement and enter as an unbound layer with a

constant layer modulus.

Strength Input Category

Modulus of Rupture – Measured at 28-day strengths. Elastic Modulus – Measured at 28-day strengths. Minimum Elastic Modulus – Modulus representing total

destruction of layer. The same strength input categories are used

for all chemically stabilized materials.

Semi-Rigid Pavements


Total Destruction of Layer 28-Day Strength 28-Day Elastic Modulus

Strength Input Category

Semi-rigid pavement load related cracking

concept.

Semi-Rigid Pavements


Emax.

Emin.

Total Destruction of Layer 28-Day Strength 28-Day Elastic Modulus

Chemically Stabilized Materials for Semi-Rigid

Pavements MEPDG transfer functions were

never calibrated for semi-rigid pavements.

Thus, do not use chemically stabilized materials in terms of semi-rigid pavement designs without local calibration!


Elastic Modulus – Measured at 28-days.

Rigid Pavements Strength Input Category


Thermal Input Category

Use default values, unless transfer functions recalibrated at other values.


Lesson 4: Unbound Layers & Soils Crushed Stone, River Run Gravel,

and Other Aggregate Bases Cold Recycled Asphalt Crushed PCC Material Thick, Large Rock Fills Permeable Aggregate Base Select Fill and Embankments Subgrade Soil Strata Section 11.5

Module 4: Material & Design Inputs, New Designs Lesson 4: Unbound Layers & Soils

Input Categories: 1. Unbound (General) 2. Modulus(Resilient) 3. Sieve (Physical & Other

Properties)

Unbound Materials and Soils

Unbound Layers


Unbound Input Category

Poisson’s Ratio: Used to calculated responses.

Recommended values in Manual of Practice.

Coefficient of Lateral Earth Pressure: Used with input level 1 to determine

the resilient modulus as different depths and horizontal locations. Can also be used to determine the input

level 3 resilient modulus.

Input levels 1, 2, & 3 are the same.


Modulus Input Category

Level Description

1 Laboratory testing in accordance with AASHTO T 307

2 Correlations with other properties: • DCP, CBR, R-Value • Volumetric properties

3 Typical values; Manual of Practice


Resilient Modulus Input Level 1

32

11

k

a

octk

aar PP

pkM

+

=

τθ

Input level 1 model parameters, k1, k2, & k3, are determined from resilient modulus tests & used with finite element analysis to

calculate pavement responses.

Resilient Modulus Universal Equation:

Crushed Aggregate


Input level 1 is not included within ME Design Software.

BUT, results from resilient modulus tests can be used to determine input level 3 value at an appropriate stress state.

Resilient Modulus

Crushed Aggregate

32

11

k

a

octk

aar PP

pkM

+

=

τθ


Value is changed by month based on water content calculated by EICM. Starting value

is at optimum conditions for the

default values.

Value is not changed by month, but is assumed to be constant

throughout the year & representative of a higher water

content.

Resilient Modulus: 1. Global default

values; level 3. 2. Measured in using

AASHTO T-307.

Four values. Module 4: Material & Design Inputs, New Designs

Lesson 4: Unbound Layers & Soils

110

114

118

122

126

130

5 6 7 8 9 10 11 12 13 14 15

Gravimetric Moisture Content (%)

Dry

Uni

t Wei

ght (

pcf)

wopt

γdmax

REMEMBER: Default resilient

modulus values are at optimum water

content & maximum dry density.

A key issue; Input Compatibility is

required!

● Standard? ● Modified? ● Or Other Effort?


Remember Input Compatibility: Is the correlation test result

measured at optimum conditions?


Correlation with Other Properties Strength/Index Property Model

CBR

R-Value; R

AASHTO layer coefficient; ai

Plasticity Index (PI) & Minus #200 (P200)*

Dynamic Cone Penetration Rate, (DCP)* 12.1

292DCP

CBR =

( )( )PIPCBR

200728.0175

+=

=

14.030000 i

raM

( ) 6.02555 CBRM R =

( )ValueRM R −+= 5551155


Monthly values are not recommended for input

level 2; let the EICM determine the monthly

modulus values.


Limiting Modulus Criteria for Unbound Layers

1000

10000

100000

1000 10000 100000

Mod

ulus

of u

pper

laye

r, ps

i

Modulus of lower layer (psi)

BASE

4 in.

10 in.

6 in.

8 in.

1000

10000

100000

1000 10000 100000

Mod

ulus

of u

pper

laye

r, ps

i

Modulus of lower layer (psi)

SUBBASE

4 in.

10 in.

6 in.

8 in.

Corp of Engineers Data Corp of Engineers Data

Apply criteria at the time of construction.


Sieve Input Category


Properties in this Category: • Gradation • Atterberg Limits • Saturated Hydraulic Conductivity • Specific Gravity • Water Content & Dry Density

Boring drilled to determine predominant soil strata.

Engineering decision to determine property inputs for soil strata.

Each Major Soil Strata: ● Atterberg Limits ● Gradation ● Is Layer Compacted ● Saturated Hydraulic

Conductivity ● Specific Gravity ● Soil-Water

Characteristics ● Maximum Dry

Density & Optimum Water Content


Two important properties: 1. Water Content 2. Dry Density

Values define the starting resilient modulus and must be tied to the resilient modulus previously entered. Resilient Modulus: ● Optimum water content & maximum dry density. ● Water content & dry density at construction. ● Water content & dry density for input level 2 test results.

Remember input

compatibility!


module 2: climate input

Documents