S55_Design Values of Resilient Modulus of Stabilized and Non-Stabilized Base_LTC2013

7/29/2019 S55_Design Values of Resilient Modulus of Stabilized and Non-Stabilized Base_LTC2013

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LTRC

Design Values of Resilient Modulus for Stabilizedand Non-Stabilized Base

Presented By

Khalil Hanifa, E.I.Geotechnical Research Engineer

10-3GT


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Overview

o Background

o Implementation Statemento Objectiveo Scopeo Methodologyo Discussion of Results (Preliminary)o Conclusions/Recommendations (Preliminary)

o Key Questions from the PRCo Updated Testing Scopeo Questions and Comments


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Background

Co-PIs: Gavin Gautreau, P.E.Sr. Geotechnical Research Engineer

Murad Abu-Farsakh, Ph.D., P.E.

Associate Professor-Research, GERL Manager

Manager: Zhongjie Doc Zhang, Ph.D., P.E.

Pavement & Geotechnical Administrator


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Implementation Statement

This research is expected to establish resilientmodulus design values for stabilized and non-stabilized base course materials which can be used

as Level 2 input in AASHTOWare Pavement MEDesign (formally DARWin-ME)


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Objective

To determine resilient modulus design valuesfor typical base course materials, asallowed by LADOTD specifications.


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Scope

Three stabilized soil types (classified as A-2-4, A-4, and A-6, according to the AASHTO soil classification) wereevaluated as bound base materials. Three aggregates

types (Mexican Limestone and Recycled PCC (crushed))were evaluated as unbound base materials.


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A laboratory testing program consisting of physicalproperties tests, tube suction tests, and repeatedloading triaxial (RLT) resilient modulus tests were

performed on the bound and unbound base materials.

Methodology


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Physical properties tests were performed in accordancewith LADOTD standard testing procedures to providecharacterization and classification information for the

tested base materials.

Methodology


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Methodology

Test LADOTD Testing Procedure

Atterberg Limits TR 428-67

Sieve/Hydrometer Analysis TR 407-99

Sieve Analysis (Aggregates) TR 113-11

Moisture-Density Relationship

(Standard Proctor)

TR 418-98 Method B (Soils)

Moisture-Density Relationship

(Modified Proctor)

TR-418-98 Method G

(Aggregates)

Classification of Soils TR 423-99


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Cement Content for Stabilized Base Materials

LADOTD often utilizes a cement stabilized base course

design in accordance with standard testing procedureTR 432-02.

Methodology


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Tube Suction Tests

The tube suction test is a procedure to approximate free

moisture content in soils through capillary action bymeasuring its dielectric constant. The measureddielectric constant of a given soil specimen gives an

indication of its moisture susceptibility.

Methodology


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Tube Suction Test Procedure

Methodology

Samples Ready for

Tube Suction Test

Capacitance Probe Taking Readings


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Repeated Load Triaxial (RLT) Resilient Modulus Tests

Resilient modulus test were performed in accordance withAASHTO procedure T 307-99 standard method.

Methodology


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Repeated Load Triaxial (RLT) Resilient Modulus Tests(Sample Preparation)Stabilized Base Materials

Methodology

Hammer and

Mold

Sample

Compaction

Compacted

Sample

Sample Being

Tested


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Repeated Load Triaxial (RLT) Resilient Modulus Tests(Sample Preparation)Unbound Base Materials

Methodology

Vibratory

Compactor and

Mold

Sample

Compaction

Compacted

Sample

Sample Being

Tested


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Methodology

Material% Cement (By

Weight)Target

7-day

curing

28-day

curing

A-2-4% to achieve

300 psi

+2% 3 samples 3 samples

Opt. 3 samples 3 samples

-2% 3 samples 3 samples

A-4% to achieve

300 psi




A-6% to achieve

300 psi




Mexican

LimestoneN/A

+2% 3 samples

Opt. 3 samples

-2% 3 samples

Recycled PCC

(Crushed)N/A

+2% 3 samples

Opt. 3 samples

-2% 3 samples


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Resilient Modulus Testing Sequences

Methodology

Sequence

Number

Confining

Pressure (psi)

Max. Axial

Stress (psi)

Cyclic Stress

(psi)

Constant

Stress (psi)

No. of Load

Applications

(Conditioning) 15 15 13.5 1.5 1000

1 3 3 2.7 0.3 1002 3 6 5.4 0.6 100

3 3 9 8.1 0.9 100

4 5 5 4.5 0.5 100

5 5 10 9.0 1.0 100

6 5 15 13.5 1.5 100

7 10 10 9.0 1.0 100

8 10 20 18.0 2.0 100

9 10 30 27.0 3.0 100

10 15 10 9.0 1.0 100

11 15 15 13.5 1.5 100

12 15 30 27.0 3.0 100

13 20 15 13.5 1.5 100

14

20

20

18.0

2.0

100

15 20 40 36.0 4.0 100


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Review of Resilient Modulus Models

Methodology


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Regression Analysis

Statistical analysis was conducted using SAS Institute Inc.

software to evaluate the resilient modulus data andestablish k1, k2, and k3 values for each model beingevaluated.

Methodology


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Physical Properties of Materials Tested

Discussion of Results

Material LL (%) PL (%) PI (%)dmax

(pcf)

opt

(%)

A-2-4 20 12 8 123.0* 10.4*

A-4 23 14 9 121.2* 11.3*

A-6 32 20 12 107.2* 15.9*

Mexican

LimestoneN/A N/A N/A 125.1** 10.1**

Recycled PCC

(Crushed)N/A N/A N/A 118.6** 12.0**


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Standard Proctor Compaction

Curves for Raw Soils

Modified Proctor Compaction

Curves for Aggregates


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Cement Content for Stabilized Base Materials


Standard Proctor Compaction

Curves for Cement Stabilized

Soils

7-day Cement Curves for

Cement Stabilized Materials


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Tube Suction Test Results


A-2-4

A-4 A-6 Mexican

Limestone

Recycled PCC

(Crushed)

0

2

4

6

8

10

12

Maxi

mumD

VValue

Marginal

Good


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Resilient Modulus Tests


Material% Cement (By

Weight)Target

Moisture

Content (%)7-day curing 28-day curing

A-2-4 4

+2% 12.4 3 samples 3 samples

Opt. 10.4 3 samples 3 samples-2% 8.4 3 samples 3 samples

A-4 4


Opt. 11.3 3 samples 3 samples

-2% 9.3 3 samples 3 samples

A-6 6


Opt. 15.9 3 samples 3 samples-2% 13.9 3 samples 3 samples

Mexican

LimestoneN/A

+2% 12.1 3 samples

Opt. 10.1 3 samples

-2% 8.1 3 samples

Recycled PCC

(Crushed)N/A

+2% 14.0 3 samples

Opt. 12.0 3 samples

-2% 10.0 3 samples


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Resilient Modulus Tests Results

Regression Analysis Results



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Resilient Modulus Test Results

1 2 3

AVG STD CV (%)

2.8 30.1 32.4 28.7 30.4 1.87 6.15

5.8 33.4 34.1 30.3 32.6 2.02 6.20

8.3 38.4 36.1 42.0 38.8 2.97 7.66

4.6 62.4 64.7 52.3 59.8 6.60 11.039.2 62.9 68.2 55.0 62.0 6.64 10.71

13.8 69.5 70.1 60.1 66.6 5.61 8.43

d (psi)3 (psi)

Sample Number

Mr (ksi)

A-2-4 (Opt.) 7-day Curing

3

5

1 2 3

AVG STD CV (%)

2.8 70.6 79.4 68.1 72.7 5.94 8.16

5.8 67.5 78.6 65.2 70.4 7.17 10.17

8.3 62.5 72.5 63.4 66.1 5.53 8.36

4.6 118.9 119.0 115.1 117.7 2.22 1.89

9.2 105.6 114.0 107.6 109.1 4.39 4.02

13.8 93.3 110.9 102.8 102.3 8.81 8.61

A-2-4 (Opt.) 28-day Curing

Sample Number

3 (psi) d (psi)

5

Mr (ksi)

3


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1 2 3

AVG STD CV (%)

2.8 32.9 32.5 26.3 30.6 3.70 12.11

5.8 30.0 29.2 26.1 28.4 2.06 7.24

8.3 28.7 28.0 25.4 27.4 1.74 6.35

4.6 64.2 56.5 53.4 58.0 5.56 9.589.2 61.1 57.4 56.1 58.2 2.59 4.46

13.8 60.2 61.5 62.4 61.4 1.11 1.80

3

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A-2-4 (-2%) 7-day Curing

Sample Number

3 (psi) d (psi)Mr (ksi)

1 2 3

AVG STD CV (%)

2.8 65.3 69.0 63.1 65.8 2.98 4.53

5.8 60.2 62.8 58.2 60.4 2.31 3.82

8.3 57.9 53.4 56.1 55.8 2.26 4.06

4.6 142.3 130.2 116.3 129.6 13.01 10.04

9.2 129.4 120.9 113.3 121.2 8.05 6.65

13.8 121.5 118.0 111.1 116.9 5.29 4.53

5

Sample Number

3 (psi) d (psi) Mr (ksi)

3

A-2-4 (-2%) 28-day Curing


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1 2 3

AVG STD CV (%)

2.8 25.8 21.0 20.6 22.5 2.89 12.88

5.8 28.2 29.3 26.2 27.9 1.57 5.63

8.3 31.0 38.4 32.0 33.8 4.01 11.88

4.6 51.7 65.5 38.4 51.9 13.55 26.13

9.2 43.6 62.6 44.9 50.4 10.61 21.07

13.8 50.1 61.8 52.0 54.6 6.28 11.49

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5

A-2-4 (+2%) 7-day Curing

Sample Number


1 2 3AVG STD CV (%)

2.8 52.4 51.9 50.1 51.5 1.21 2.35

5.8 50.8 47.4 45.1 47.8 2.87 6.00

8.3 47.5 46.9 44.3 46.2 1.70 3.68

4.6 98.8 96.7 86.2 93.9 6.75 7.19

9.2 98.5 92.3 80.9 90.6 8.93 9.86

13.8 94.0 89.0 77.0 86.7 8.74 10.08

5

Sample Number


3

A-2-4 (+2%) 28-day Curing


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Regression Analysis Results


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Resilient modulus is not a constant value but varies with stressconditions

For stabilized materials at 7-day curing, moisture content has an

impact on resilient modulus For stabilized materials, increasing the curing period from 7-day to

28-day caused a significant increase in resilient modulus. Also theimpact of moisture content on resilient modulus is not as critical at

28-day curing as compared to 7-day curing For aggregate materials, moisture content has an impact on

resilient modulus

Conclusions


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The three models evaluated to establish materials coefficients allperformed well in predicting resilient modulus

The data developed from all three models can be utilized to

generate Level 2 inputs for base course resilient modulus inAASHTOWare Pavement ME Design

Conclusions


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Recommendations

The following initiatives are recommended in orderto facilitate the implementation of this study

1. Make Model 1 (NCHRP Model), Model 2 (UKTC

Model), and Model 3 (Uzan Model) for estimatingthe resilient modulus of bound and unbound basematerials readily available for use by the design

personnel of LADOTD2. Implement the results of this study into the

current design procedure


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Key Questions from the PRC

1. Resilient Modulus Values Appear To Be Low

Based on Literature Review, Resilient ModulusValues Appear To Be Too Low

2. Is There A Relationship Between UnconfinedCompressive Strength and Modulus?

As Strength Increases Modulus GenerallyIncreases

3. Are There Models That Correlate UnconfinedCompressive Strength to Modulus?

Yes and the Models That Relate to the Testing

Scope of 10-3GT Will Be Investigated


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Questions/Comments from PRC

4. Is There A Minimum Percentage of CementRequired In The Field?

Yes, 6% (By Volume) Due to Variation in Spread

Rate and to Assure Uniform Mixing5. k1, k2, and k3 Parameters Can Not Be Used in

Pavement ME Design

These Models Can Not Be Used For Chemically

Stabilized Materials in Pavement ME Design

6. Recommend A Range of Typical Design Values

of Resilient Modulus for Each Tested Material

A Range of Typical Values Will Be Provided


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Key Questions from the PRC

7. Cement Treated Base (150 psi) and BCS Materials WereNot Included In This Study

These Materials and Other Materials Recommended by

the PRC Will Be Included in the Updated Testing Scope8. What base courses are typically constructed for

Louisiana roadways?

Discussed in the Summary of the Survey Provided tothe District Lab Engineers (Upcoming Slides)


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Review of District Lab Survey

4 Districts Replied, 5 Districts Did Not Reply

Response No Response

District 02 (New Orleans) District 04 (Bossier City/Shreveport)

District 03 (Lafayette) District 05 (Monroe)

District 61 (Baton Rouge) District 07 (Lake Charles)

District 62 (Hammond) District 08 (Alexandria)

District 58 (Chase)


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1. Base Courses Constructed in Districtsa. 302: Cement Stabilized Base Course (300 psi)b. 303: In-Place Cement Stabilized Base Course (300 psi)c. 308: In-Place Cement Treated Base Course (150 psi)d. Other: Stone, RPCC, BCS and Asphalt Base Course

2. Is There a Minimum Percentage of Cement Required inthe Field? 6% (By Volume) Due To:

a. Variation in Spread Rateb. To Assure Uniform Mixing


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3. How Much Does Variation in Moisture Content (the2% of Optimum Range Allowed During Construction)Affect Strength in the Field?

a. The Lab Engineers informed me that they have no wayof knowing this

b. I suggested that we investigate it since it is related tothe scope of project 10-3GT


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1. Existing Materials

Note: A-2-4, A-4 and A-6 will be treated with

6%, 6% and 8% cement (by weight) respectively, an

Increase of 2% from previous testing

Updated Testing Scope

Material

Unconfined Compressive StrengthTests

Resilient Modulus Tests

+2% Opt. -2% +2% Opt. -2%

A-2-4 3 samples 3 samples 3 samples 3 samples 3 samples 3 samples

A-4 3 samples 3 samples 3 samples 3 samples 3 samples 3 samples

A-6 3 samples 3 samples 3 samples 3 samples 3 samples 3 samples


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2. New Materials

a. Cement Stabilized Base Course (300 psi design strength)

b. In-Place (Recycled) Cement Stabilized Base Course (300 psi design strength)

c. In-Place (Recycled) Cement Treated Base Course (150 psi design strength)d. Recycled Soil Cement (300 psi design strength)

e. Composite Base Course (4 Stone/8 Soil Cement)

Testing Scope:

1. Gradation/Hydrometer Analysis2. Atterberg Limits

3. Moisture-Density Relationship

4. Unconfined Compressive Strength Tests (7-day)

5. Resilient Modulus Tests (7-day and 28-day)

Testing Plan


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3. In-House Literature Review

a. Kentucky Limestone

b. Mexican Limestone

c. BCSd. Asphalt Base Course

An in-house literature review will be conducted on these materialsto gather information as it relates to the testing scope of 10-3GT

Testing Plan


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Questions?

Documents

S55_Design Values of Resilient Modulus of Stabilized and Non-Stabilized Base_LTC2013