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Concrete Airport Pavement Workshop, Nov 4-5, 09 Cement-Stabilized Base Courses Cement Stabilized Base Courses Fares Y. Abdo, P.E. Market Manager, Pavements Portland Cement Association

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Page 1: 1 Cement Treated Bases_Abdo

Concrete Airport Pavement Workshop, Nov 4-5, 09

Cement-Stabilized Base CoursesCement Stabilized Base Courses

Fares Y. Abdo, P.E.,Market Manager, PavementsPortland Cement Association

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Fundamentals

Cement-Treated Base CoursesFundamentals

Materials

Mix Design

Thickness Designg

Construction

Case StudiesCase Studies

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Cement-Based Pavement MaterialsRoller Compacted ConventionalRoller-Compacted Concrete

Conventional Concrete

PerviousConcrete

FAA

FAA C t T t d

Soil-Cementent

FAA Econocrete

P-306

Cement-Treated Base/Subbase

P-301 &P-304 Flowable Fill

Cement-Treated

Base

ent C

onte

Flowable Fill

Cement-ModifiedSoil

Full-DepthReclamationC

em

Water Content

Soil

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Definition

Cement-Treated Base – a intimate mixture of native and/or manufactured aggregates with measured amounts of portland cement (and possibly other cementitious materials) and water that hardens after compaction and curing to form a strong durable paving material

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What materials can be treated with cement?

Soils (sand, silt, clay)GravelGravelShaleC h d tCrushed stoneSlagRecycled HMARecycled concrete

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Are all materials suitable for CTB?

Problem Soils

Organic soils

Acid soils

Sulfate soilsSulfate soils

Uniform sands

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Why Use CTB?Economical pavement baseEconomical pavement base

Decreased base thickness compared to unbound aggregate base

Structural properties maintained under varying moisture conditions

High stiffness inhibits fatigue cracking and High stiffness inhibits fatigue cracking and rutting of asphalt surface

Sustainable paving optionSustainable paving option

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FAA Base/Subbase Approved FAA Base/Subbase Approved Materials

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P f B /S bb CPurpose of Base/Subbase Courses(FAA AC 150/5320-6E)

Flexible pavements

Principal structural components Base

Asphalt

Principal structural components

Distribute the loads to the f d ti

Base

Subbase(Req. if CBR<20)

foundation Subgrade

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Improved Performance in Rutting and Fatigue CrackingP P

Cement-Treated BaseUnstabilized Granular Base

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P f B /S bb CPurpose of Base/Subbase Courses(FAA AC 150/5320-6E)

Flexible pavements

Principal structural component Base

Asphalt

Principal structural component

Distribute the loads to the f d ti

Base

Subbase(Req. if CBR<20)

foundation

Rigid pavements

Subgrade

Provide uniform stable supportConcrete

Subbase

Subgrade

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Materials for Base CourseMaterials for Base CourseFAA AC 150/5320-6E Flexible Pavement Design

I B C M G L d Item Base Course Max. Gross Load, lbs.

P-208 Aggregate Base 60 000P 208 Aggregate Base 60,000

P-209 Crushed Aggregate Base 100,000

P-211 Lime Rock Base N/A/

P-219 Recycled Concrete Aggregate Base 100,000

P-304 Cement Treated Base N/A/

P-306 Econocrete Subbase N/A

P-401 Plant Mix Bituminous Pavements N/A

P-403 HMA Base N/A

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Materials for Subbase CourseMaterials for Subbase CourseFAA AC 150/5320-6E Flexible Pavement Design

I S bb C 1 F P i Item Subbase Course1 Frost Penetrating Subbase

P-154 Subbase CourseP 154 Subbase Course

P-210 Caliche Base Course

P-212 Shell Base Course

P-213 Sand Clay Base Course X

P-301 Soil Cement Base Course X

1. Materials acceptable for base course can also be used for subbase course

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Materials for Sbbase CourseMaterials for Sbbase CourseFAA AC 150/5320-6E Rigid Pavement Design

I S bb C M G L d Item Subbase Course Max. Gross Load, lbs.

P-154 Subbase Course 100,000,

P-208 Aggregate Base Course 100,000

P-209 Crushed Aggregate Base Course 100,000

P-211 Lime Rock Base Course 100,000

P-301 Soil Cement Base Course 100,000

P 304 Cement Treated Base Course N/AP-304 Cement Treated Base Course N/A

P-306 Econocrete Subbase Course N/A

P-401 Plant Mix Bituminous Pavements N/A

P-403 HMA Base Course N/A

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Engineering Properties of CTB

P 1 FAA P 301 FAA P 304 PCA CTBProperty1 FAA P-301(Soil Cement)

FAA P-304(CTB)

PCA CTB

7-Day Compressive N/A2 Under PCC: 300 min.; Strength, psi 500 min.; 1000 max.

Under HMA:750 min.; 1000 max.

800 max.

Elastic Modulus, ksi 250 500 600-1000

Poisson’s Ratio 0.20 0.20 0.15

1. Refer to FAA AC 150/5320-6E for durability requirements2. FAA recommendations for P-301 are based on wet-dry and freeze-thaw tests

and strength should increase with age

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CTB Mix Design

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St i f B l B tStrive for a Balance BetweenStrength and Performanceg

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Mixture Design-Step 1Determine moisture-density relationship

Select expected median cement content Select expected median cement content (e.g. 6% by estimated dry weight)

Perform standard or modified Proctor test Perform standard or modified Proctor test (ASTM D558 or ASTM D1557)

Construct moisture-density curve

Determine optimum moisture content and maximum dry density

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Moisture-Density Relationship

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Mix Design-Step 2Mold specimens for compressive strength testing

Select range of cement contents ( 4% 6% d 8% b d i ht f t i l) (e.g. 4%, 6% and 8% by dry weight of material) Use percent OMC from Step 1 and Mold two specimens per cement content (ASTM specimens per cement content (ASTM D559/560 or ASTM D1632) Perform compressive strength testing Perform compressive strength testing (ASTM D1633)Plot cement content versus compressive Plot cement content versus compressive strength

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Strength Testing

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Strength vs. Cement Content1000

800

900

ngth

, psi

600

700

ssiv

e St

ren

400

500

y C

ompr

es

200

3007-da

y

3 4 5 6 7 8 9

Cement Content, %

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Mix Design-Step 3Determine moisture-density relationship of target cement content

Perform standard or modified Proctor test (ASTM D558 or ASTM D1557)

Construct moisture-density curve

Determine optimum moisture content and Determine optimum moisture content and maximum dry density

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Durability TestingSpecimens containing various cementitious contents molded per ASTM D558 and tested per:

ASTM D559; wet-dry cycles

ASTM D560; freeze-thaw cyclesASTM D560; freeze thaw cycles

Select min. cement content that meets weight loss limits set by agency having jurisdictionloss limits set by agency having jurisdiction

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Thickness Design

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Thickness Design■ FAA: FAARFIELD Computer Program

■ PCA Methods of Thickness Design ■ PCA Methods of Thickness Design

■ Experience

M h i ti E i i l M th d■ Mechanistic-Empirical Methods

■ AASHTO MEPDG (guide accepted)

■ PCA-Pave (near completion)

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Thickness Design■ Factors

■ Subgrade Strength■ Subgrade Strength

■ Pavement Design Period

T ffi■ Traffic

■ Typical Thickness

■ Heavy traffic: 6 to 9 inches

■ Highways and airport runways and g y p ytaxiways: 6 to 12 inches

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Construction

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Construction

■ Two methods

■ Plant Mix

Road Mix (in place)■ Road Mix (in-place)

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Plant Mix: PuggmillHigh production

Usually close or on-site

Mob/demob cost

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Continuous Pugmill Mixing Chamber

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■ Highly accurate Plant Mix: Central Concrete Batch Plant

■ Highly accurate proportioning

■ Local availability■ Local availability

■ Smaller output capacitycapacity

■ Longer mix times than conventional concreteconventional concrete

■ Frequent cleaning

■ Dedicated production

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Plant Mix: Dry Concrete Batch Plant■ Highest local availability

■ Desirable method for the smaller-sized jobs

■ 2-step process

■ Feed into transit mixers

■ Discharge into dumps

■ Low production■ Low production

■ Frequent cleaning

S i■ Segregation

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Construction - Road Mix

■ In-situ or mixed in place materials

■ Wider variety of materials

■ Dry or slurry cement application methody o s u y ce e t app cat o et od

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Road Mix Method

1. Spread cement

2. Add water if necessary and mix

3. Compactp

4. Grade

5 Cure5. Cure

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Portland Cement Addition

Dry spread

Slurry spread

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Addition of Water

Gravity dump and mix

Via drum of mixer

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Road Mixing

With water

Without water

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Traffic loading/agency requirements

Plant vs. Road Mix ConsiderationsTraffic loading/agency requirements

FAA P-304 spec includes plant mix only

Quality of in-situ materialsQ y

Cost

Haul distances: material sources, plant, jobsitep j

Design thickness (one or multiple lifts)

Sustainable considerations (Reduce, Reuse and Recycling)

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Dust controls/location of project

Plant vs. Road Mix ConsiderationsDust controls/location of project

Tuscaloosa, AL Palo Verde, AZ

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Spreading/Placing

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Grading/Compaction

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Compaction

■ High density is critical for strength and durability

■ Steel-drum

■ Rubber-tire roller

■ Sheepsfoot roller■ Sheepsfoot roller

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Curing

■ Required for surface durability and normal strength gaing

■ Needed to retain moisture

■ Three methods:■ Three methods:

▪ Moist Cure

▪ Concrete Curing Compound▪ Concrete Curing Compound

▪ Asphalt Emulsion

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Moist Cure

■ Continuous ■ Continuous operation

P t i ■ Prevent excessive drying

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Concrete Curing Compound

■ White-pigmented concrete curing compounds

■ Provide adequate coverage

■ May form a bond breaker

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Bituminous Curing Compound

E ll t ■ Excellent moisture barrier

G d f h lt ■ Good for asphalt cap

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Applications

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L l r d

Where are stabilized materials used?Low volume roadways

Residential streets

State routesState routes

Interstate highways

Airport runways and taxiwaysAirport runways and taxiways

Parking lots

Industrial storage facilitiesIndustrial storage facilities

Port facilities

Truck terminalsIn other words…

Truck terminals

Commercial sites any pavement structure!

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Residential Streets

Bells Crossing, Mooresville, NC, 2008

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V lExample: County Road Original Design

Value-Engineered

Option■ Upgrade 2-lane to 4-lane route■ Value Engineered Option

3.5”

Asphalt Int. & Surface

■ Value-Engineered Option■ $900,000 savings on

238,000 SY ($3.78/SY) ■ Faster construction (5 months Asphalt Base Crushed

Asphalt Int. & Surface

C t

8” Crushed

(savings)

■ Less mined and processed materials

8”Crushed

Stone BaseCement-

Treated Base

8Stone Base

Subgrade

Subgrade

SC County Road 5

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Parking AreasSustainable ContributionsDesign/Bid As ■ Reduced

export/import/fuel use■ Less mined and RCC6” 8”4”4” AsphaltAsphalt4” Asphalt

Design/Bid Section

As Constructed

■ Less mined and processed materials

■ Reduced excavation

RCC

Soil-Cement

6”-8”

6”12”12”Crushed Crushed

44

12”Crushed

4

■ Faster construction■ Cooler pavement■ Used in situ materialsSubgrade

Base612”12” Stone

BaseStone Base

12” Stone Base

■ Used in-situ materials■ Less damage to area

roadsSubgradeSubgradeSubgrade

BMW, SC, 2009

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Washington Dulles Airport Runway 4, 2008p y ,

18” PCC w/ dowelled transverse

j i t t 20 ft joints at 20 ft

6” CTB, 6% cement

12” Cement-Stabilized Subgrade,

5% cement

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Washington Dulles Airport Runway 4p y

■ Runway 4 completed in 2008■ Runway 12 was completed in

2004

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FedEx Hub at Alliance Airport Fort Worth, TX,

Taxiway & Ramp

1997

14” PCC

Taxiway & Ramp

Truck Terminal & C t i St g14” PCC Container Storage

9” CTB10” JRCP

9” Cement-Treated Subgrade

6” Cement-Treated Subgrade

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FedEx Hub at Alliance Airport Fort Worth, TX

■ 50-yr design lifeC l t d i 1997■ Completed in 1997

■ 330,000 yd2

■ Cement-treated subgrade■ 7 % cement, 250 psi,

reduced PI from 38 to less than 12

■ Cement treated base■ Cement –treated base■ 750 psi at 28 days

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DFW SE Perimeter Taxiway, 2008y,■ First perimeter taxiway in U.S.■ Built for safety and reduce

congestion delays

18” CRCP

congestion delays

18 CRCP

12” CTB

12” Lime-Treated Subgrade

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DFW SE Perimeter Taxiway■ Completed in 2008■ 225,000 yd2

■ Data will be analyzed before ■ Data will be analyzed before building the remaining 3 loops

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McGhee Tyson AirportKnoxville, TN, 2008■ Completed in 2008■ 9,000 yd2

■ CTB per FAA P 304■ CTB per FAA P-304

16” PCC

6” CTB, 5% (C+FA)

8” Lime-Treated Subgrade

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Charlotte-Douglas Airport, 2008■ Completed in 2008■ 256,000 yd2

■ CTB per FAA P 304■ CTB per FAA P-304

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Dover AFB, Delaware, 2008■ Old concrete and asphalt

crushed and recycled50% l d d 50% i i ■ 50% recycled and 50% in-situ soil; sandy clays and clear sand

■ CTB 12” thick■ CTB 12 thick■ 42 to 80 lb/SY depending on

the in-situ and recycled materials

■ 300,000 SY ■ 58 days

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M I f tiMore Information

www.cement.org/pavementswww.cement.org/[email protected]