Evaluation of Subgrade Stabilization on Pavement Performance of Subgrade... · Evaluation of...

Click here to load reader

  • date post

    12-Apr-2018
  • Category

    Documents

  • view

    216
  • download

    1

Embed Size (px)

Transcript of Evaluation of Subgrade Stabilization on Pavement Performance of Subgrade... · Evaluation of...

  • Evaluation of Evaluation of SubgradeSubgradeStabilization on Pavement Stabilization on Pavement

    PerformancePerformance

    Louisiana Transportation Research CenterLouisiana Transportation Research Center

    Mark Morvant, P.E.Mark Morvant, P.E.Pavement & Geotechnical Research AdministratorPavement & Geotechnical Research Administrator

  • Lime Treated Working Table

  • Subgrade

    Dry Embankment

    Subgrade

    Existing Subgrade

    New Embankment

    Saturated

    DryClay

    Silt

    Usable soils

    High silt soils (no silt restriction)

    SubgradeSubgrade TreatmentTreatment

    Treated Layer

    Treated Layer

  • SubgradeSubgrade PropertiesProperties

    lSoil Type Heavy Clay Lean clay Silt

    lSoil Condition Wet Optimum Dry

    lStabilization Agents Cement Lime Lime/Fly Ash Cement/Slag

  • Identification and Identification and Stabilization Methods for Stabilization Methods for

    Problematic Silt SoilsProblematic Silt SoilsCivil & Environmental Engineering DepartmentCivil & Environmental Engineering Department

    University of New OrleansUniversity of New Orleans

    Principal InvestigatorsPrincipal InvestigatorsKenneth Kenneth McManisMcManis, Ph.D., P.E., Ph.D., P.E.

    MysoreMysore NatarajNataraj, Ph.D., P.E., Ph.D., P.E.

    Sponsored by Louisiana Transportation Research Center

  • Cyclic Stress-Strain Curves

    0

    500

    1000

    1500

    2000

    2500

    3000

    0 5 10 15 20 25

    Strain, %

    App

    lied

    Loa

    d, p

    sf

    Acadia Soil

    Chase Brown Soil

    Chase White Soil

    DeRidder Brown Soil

    DeRidder White Soil

    Natchitoches K2 Soil

    ALF UU Tests

    ALF CD Test

    UNO Research StudyUNO Research StudyHigh Silt SoilsHigh Silt Soils

  • 15 psi

    35 psi

    37 psi

    5 psi

    (+4% opt)

    Silt content 50 %

  • 5 psi

    20 psi

    50 psi

    90 psi

    150 psi

    (+4% opt)

    Silt content 50 %

  • 70% Silt

    lime

    Lime/fly ash

    CementUntreated

    Slag Cement

    High Silt / High MoistureHigh Silt / High Moisture

  • High Silt / High MoistureHigh Silt / High Moisture

    lime

    Cement

    Lime/fly ash

  • LTRC Guideline Recommendation

    In-Place SubgradesCement Treatment Subgrades - Soils identified with a silt

    content of 50 percent or greater and also a PI of 10 or less.

    Lime Treated Subgrades Wet soils identified with a PI greater than 15.

  • Evaluation of a Evaluation of a SubbaseSubbaseLayer on Pavement Layer on Pavement

    PerformancePerformancel Laboratory Evaluation

    Doc Zhang Louay Mohommad

    l Field Evaluation Gavin Gautreau Kevin Gaspard District Laboratory Engineers

    l Accelerated Loading Evaluation Masood Rasoulian Bill King

    l Numerical Analysis (proposed) Freddy Roberts (LTU) Murad Abu-Farsakh Louay Mohammad

  • Laboratory ProgramLaboratory Program

    l Subgrade soils Silt> 65% PI 25

    l Moisture conditions Wet Optimum Dry

    l Stabilization additives Portland Cement Lime Lime / fly ash

    l Characterization Gradation Atterberg limits Eades and Grim pH test (lime)

    l Strength testing Unconfined compression Triaxial tests Resilient modulus CBR

    l Durability Long term fatigue (rut) Wet dry cycles Tube Suction Test

  • Field Test ProgramField Test Program

    l Silt subgrade test sections PI 25 Lime treated working table Lime stabilized subgrade Lime/fly ash stabilized subgrade

  • Falling WeightDeflectometer

    Field Evaluation EquipmentField Evaluation Equipment

    Dynamic Cone Penetrometer

  • -40.0

    -30.0

    -20.0

    -10.0

    0.0

    10.0

    20.0

    30.0

    0 50 100 150 200 250 300

    Blow Count

    Cumu

    lative

    Penet

    ration

    , cm

    -40.0

    -30.0

    -20.0

    -10.0

    0.0

    10.0

    20.0

    30.0

    0 50 100 150 200 250 300

    Blow CountCu

    mulat

    ive Pe

    netrat

    ion, c

    m

    Dynamic Cone Dynamic Cone PenetrometerPenetrometer

    Stone

    Cement TreatedSubgrade

    Compacted Embankment

    Blow count Blow count

    Dep

    th(c

    m)

    Dep

    th

    0

    20

    40

    60

    10

    30

    50

    70

    Dep

    th

    0

    20

    40

    60

    10

    30

    50

    70

    5 mm/blow

    1 mm/blow

    7 mm/blow

    Dep

    th(c

    m)

  • 0

    1020

    30

    4050

    60

    7080

    0 10 20 30 40 50 60 70 80 90 100 110 120

    DCP BlowsDe

    pth

    (cm

    )

    Stone Base

    Lime Treated Subgrade

    2.5 mm/blow

    20 mm/blow

    80 mm/blow

  • Falling Weight Falling Weight DeflectometerDeflectometer

    Aggregate Base

    Treated Subgrade

  • Cement TreatedCement TreatedWorking Table DesignWorking Table Design

    LA 182 / LA 89LA 182 / LA 89St. Landry ParishSt. Landry Parish

  • LA 182 / LA 89LA 182 / LA 89BeggsBeggs to Parish Lineto Parish Line

    St. Landry ParishSt. Landry Parish

    Log mile

    Log mile

    Log mile

    Log mile

    Log mile

    LA 182LA 97

    Silt Pumping Criteria

  • LA 182 / LA 89LA 182 / LA 89BeggsBeggs to Parish Lineto Parish Line

    St. Landry ParishSt. Landry Parish

    Pumping Subgrade

    3.5 Asphalt pavement

    12 Lime TreatedWorking Table (10%)

    12 Cement TreatedWorking Table (4%)

    12 Cement Treated Base ( 6%)

    Firm Subgrade

  • LA 182/97 Test SectionsLA 182/97 Test Sections1. Cement treated clay subgrade: 30+00 40+862. Lime treated clay subgrade : 40+85 53+053. Lime treated silt subgrade : 494+44 505+934. Cement treated silt subgrade 506+61 546+27

    LA 182LA 97

    1 2

    3 4

    Untreated Zone

    Silt Pumping Criteria

    Log mile

    Log mile

    Log mile

    Log mile

    Log mile

  • LA 182/97 Test SectionsLA 182/97 Test Sections

    0

    50

    100

    150

    200

    250

    300

    350

    03/20/03 06/28/03 10/06/03 01/14/04 04/23/04 08/01/04 11/09/04

    FWD

    mod

    ulus

    (ks

    i)

    Cement treated silt subgrade

    Lime treated silt subgrade

    Untreated silt subgradeCement treated silty

    clay subgrade

    Lime treated silty clay subgrade

  • LA 182 Test SectionsLA 182 Test SectionsDCP Strength ValuesDCP Strength Values

    0

    2

    4

    6

    8

    10

    12

    12/27/03 3/17/04 6/5/04 8/24/04 11/13/04

    DC

    P (m

    m/b

    low

    )

    Lime Treated Silt (10%)

    Cement Treated Silt (4%)

    Lime Treated Clay (10%)

    Untreated Firm Silt

    Cement Treated Clay (4%)

  • SubgradeSubgrade Treatment vs. Treatment vs. SubgradeSubgrade StabilizationStabilization

    l Subgrade Treatment Construction Aid Standardized Design Quality not as important Temporary Performance Less costs Faster to construct

    l Subgrade Stabilization Enhances pavement

    performance Requires laboratory design Construction Quality

    important More expensive May require more time to

    construct

  • High Silt High Silt SubgradesSubgradesLaboratory ResultsLaboratory Results

    Silt subgrade (65%) - 7 day strength

    0

    100

    200

    300

    400

    10 15 20 25 30

    Moisture content at preparation, %

    Unc

    onfi

    ned

    com

    pres

    sive

    str

    engt

    h,

    psi

    10% Lime Natural

    +4 % +8%OptimumMoisture

    4% Cement

    8% Cement

    12% Cement

  • Laboratory ResultsLaboratory ResultsHigh Silt SoilsHigh Silt Soils

    Silt Subgrade 65% - 28 day strength

    0

    100

    200

    300

    400

    500

    5 10 15 20 25

    Mositure Content, %

    UC

    S, p

    si

    10% Lime

    4% Cement

    8% Cement

    12% Cement

    OptimumMoisture +4% +8%

  • SiltySilty ClayClayLaboratory ResultsLaboratory Results

    Clay Subgrade (PI=22) - 7 day strength

    0

    100

    200

    300

    400

    500

    600

    5 10 15 20 25

    Moisture Content at molding, %

    Unc

    onfi

    ned

    Com

    pres

    sive

    Str

    ench

    , ps

    i

    Optimum moisture +4% +8%

    4% Cement

    8% Cement

    12% Cement

    Untreated

  • 0

    50

    100

    150

    200

    250

    300

    2 4 6 8 10

    Cement Percentage

    UC

    C S

    tren

    gth

    (p

    si)

    124 psi

    172 psi

    252 psi

    32 psi

    72 psi38 psi73 psi

    104 psi

    Optimum moisture

    4% above optimum moisture

    6% lime application24 hrs prior to cement

    Seven Day Strength Test Results(Dist. 07 Lab Results)

    US 171 Subgrade Soils75 % silt

  • US 171 Test SectionsUS 171 Test SectionsCement Treated Natural Cement Treated Natural

    SubgradeSubgrade (8%)(8%)

    0

    10

    20

    30

    40

    50

    60

    70

    0 5 10 15 20 25 30

    Days

    DCP (m

    m/b

    low

    )

    122+50125+00127+50untreateduntreateduntreated

    3 mm/blow

  • High Silt High Silt SubgradeSubgrade Cement Treatment

    9% by volume by bid specification 305 Adjusted by engineer as conditions warrant

    Cement & Cement / Slag Stabilization Designed for maximum benefit Strength requirement

    7 day cure strength Target strength value

    Lime fly ash (incomplete) Eades & Grimes for lime content Strength target value for fly ash content

    Moisture sensitivity (incomplete) Tube suction test Capillary soak

  • Heavy Clay Heavy Clay SubgradeSubgrade

    Lime Treatment Generally 10% by volume Adjusted by engineer as conditions warrant

    Lime Stabilization Designed for maximum benefit Strength requirement

    Natural cure vs. accelerated cure Target strength value

    Moisture sensitivity Tube suction test Capillary soak

  • EadesEades & Grimes Test& Grimes TestLime Requirement for StabilizationLime Requirement for Stabilization

    Heavy Clay PI = 47Heavy Clay PI = 47

    7

    8

    9

    10

    11

    12

    13

    0.0% 10.0% 20.0% 30.0% 40.0%

    Lime content by volume, %

    ph

    val

    ue

    pH = 12.4

    Lime Content = 18% by volume (7.5% by weight)

  • Lime Treated Heavy ClayLime Treated Heavy ClayAccelerated Cure Accelerated Cure vsvs Natural CureNatural Cure

    Heavy Clay, 18% lime

    0

    20

    40

    60

    80

    100

    120

    140

    25 27 29 31 33 35 37 39 41 43 45

    Moisture Content, %

    UC

    S, p

    si

    28day curing 7day acceleration curing

    OptimumMoisture

    Target value

    Add water during mixing

    Add additional limeto reduce moisture

  • Heavy Clay Heavy Clay SubgradeSubgradeLime StabilizationLime Stabilization

    Preliminary RecommendationsPreliminary Recommendations

    l pH Test for full lime reaction Eades & Grimes Test

    l Unconfined compression test for minimum strength Target value 100 psi 125 psi Minimum 50 psi increase from untreated

    l Specifications for maximum performance Mellowing period Additional lime based on in situ moisture Double application if necessary

  • Current Current SubgradeSubgrade Treatment Treatment PolicyPolicy

    (Working Table )(Working Table )

    l Item 304 Lime Treatment Type D compacted to the satisfaction of the

    engineer Type E compacted to 95% density Generally 10% by volume

    l S-Item Cement Treatment Refers to Item 305 Subgrade Layer By specification: 9% by volume

  • Forthcoming Research ResultsForthcoming Research Results

    SN = a1 d1 D1 + a2 d2 D2 + a3 d3 D3 + ai di Dia: Structural Coefficientd: Drainage Coefficient (d = .9)D: Thickness of Pavement Layer

    Asphalt Base Course a2 = .33

    Asphalt Pavement a1 = .44

    Treated Subgrade a4 = 00

    Stone Base a3 = .14Cement Treated Base a3= .10

    D1D2

    D3

    D4

    Subgrade Mr = ??

    Can this layer be counted on for long term structural support?

  • l Design Process DOTD pre-design DOTD post bid design Contractor post bid design

    l Stabilization Quantity Unconfined Compressive Strength Target Value Standardized Design on Soil Properties Long term moisture sensitivity

    l Construction Specifications QC/QA Meets target value Construction damage Traffic damage

    Research Result Research Result Guidelines Guidelines

  • Saturated Silt Subgrade

    Test Lane 1Standard ConstructionCement Treated Base

    Lime Treated Working Table

    2 Asphalt pavement 2 Asphalt pavement

    12 Lime Treated Subgrade (10%) 12 Cement Treated Subgrade (8%)

    8.5 Stone Base8.5 Stone Base

    Water source

    Test Lane 2Cement Treated Base

    Cement Treated Subbase

    ALF ExperimentALF Experiment

  • Potential ImpactPotential ImpactLife Cycle AnalysisLife Cycle Analysis

    0 15 30 45

    Construction$114,000/ln mi

    Mill & Overlay$67,000

    Mill & Overlay$67,000

    0 15 30 45

    Construction$96,000/ln mi

    Mill & Overlayminor patching$75,000/ln mi

    Reconstruction$96,000/ln mi

    Mill & Overlay$67,000/ln mi

    Salvage Value$33,000/ln mi

    Annualized cost = $14,300/ln mi/yr

    Annualized cost = $11,780/ln mi/yr

    20 %

  • Questions?Questions?

  • Stone Interlayer Base over Stone Interlayer Base over SubgradeSubgrade TreatmentTreatment

    12 Treated Subgrade(Subbase)

    Subgrade Soils

    2.0 AC -Wearing Course

    2.5 AC Binder Course

    4 Stone Base

    10 Cement Treated Base(a = .10)

    Stone Interlayer Base

    Cement Treated Base300 psi min.Opt moistureconstruction control

    Subbase

    Treatment optionsCementLimeLime / Fly Ash

    Existing Moisture ConditionOptWet

    75 - 100 psiConstruction control ?