sca-pca rcc design seminar

7/26/2019 Sca-pca Rcc Design Seminar

http://slidepdf.com/reader/full/sca-pca-rcc-design-seminar 1/40

Pavement Thickness Design andPavement Thickness Design and

RCCRCC--Pave SoftwarePave SoftwareGregory E. Halsted, P.E.

Pavements Engineer

Portland Cement Association

Roller Roller --Compacted Concrete Pavement:Compacted Concrete Pavement:

Design and ConstructionDesign and Construction

November 3, 2005

Atlanta, Georgia



Water Content

C

e m e n t C o

n t e n t

C as t

R o l l e d

N o W e ar i ng C o u r se

W e ar i ng C o u r se

Roller-Compacted

Concrete

Conventional

Concrete

Soil-Cement

Flowable Fill

Cement-Modified

Soil

Full-DepthReclamation

Cement-

Treated

Base

CementCement--Based PavementBased Pavement

MaterialsMaterials



DefinitionDefinition“Roller-Compacted Concrete (RCC) is a no-slump

concrete that is compacted by vibratory rollers.”

• Zero slump (consistency of damp gravel)

• No forms• No reinforcing steel• No finishing

• Consolidated withvibratory rollers

Concrete pavement placed in a different way!



Pavement Thickness Design



Engineering PropertiesEngineering Properties

• Compressive strength– 4,000 to 10,000 psi

• Flexural strength

– 500 to 1,000 psi– fr = C(f’c)1/2

• Modulus of Elasticity– 3,000,000 to 5,500,000 psi

– E = CE(f’c)1/2



Engineering PropertiesEngineering Properties

• RCC can providehigher flexural

strength thanconventionalconcrete



Mixture DesignMixture Design

Conventional concrete mixture proceduresare not appropriate!

•Not air-entrained•Lower water content•Lower paste content•Larger fine aggregate content•Nominal maximum size aggregate (NMSA)

= 1/2” or 5/8”



Important!Important!

• Dry enoughto support avibratory

roller• Wet enoughto permit

adequatedistributionof paste



Aggregate Selection Aggregate Selection

• Aggregateselection veryimportant

• Responsible for

mix workability,segregation,ease ofconsolidation

• Pre-blended orstoredseparately



Aggregate Selection Aggregate Selection– Highway base course, asphalt, or concrete

aggregates can be used– 1/2” or 5/8” NMSA

• For smooth surface, lower segregation

– Higher fine aggregate content thanconventional concrete mixes• For adequate stability under vibratory

roller– 2% to 8% passing #200 sieve• Provides paste to fill voids and maintain

tight surface



0

20

40

60

80

100

0.01 0.1 1 10 100

Sieve Opening (mm)

P e r c e n t P a

s s i n g

#200 #40 #10 #4 1/2" 1" 2"

.075 .425 2.0 4.75 12.5 25 50

Aggregate Gradation for RCC Aggregate Gradation for RCC



Cementitious MaterialsCementitious Materials

• Select materials based upon availability,economics, and design requirements:– Portland cement: Type I or II

– Fly ash– Slag or silica fume– Normally 400-600 lb/cy cementitious

(12% to 17% of dry weight)– If used, fly ash proportions are typically15% to 25%



Admixtures Admixtures• Retarders or water reducers can be

used to increase working time• Superplasticizers not used• Air entrainment not yet technologically

possible–But RCC is very freeze/thaw resistant

• Fibers seldom used, benefits have notbeen demonstrated• Newest trend in RCC mix production



Soil Compaction MethodSoil Compaction Method

1. Determine moisture content

– Construct moisture/density curve– Modified Proctor ASTM D1557

– Assume a median cement content

for example: 15 percent



MoistureMoisture--Density RelationshipDensity Relationship

140

141

142

143

144

2 3 4 5 6 7 8

Moisture Content

D

r

y

D

e

t

y

b



Soil Compaction MethodSoil Compaction Method

2. Determine cementitious materialscontent

– Use optimum moisture content– Run cement series

• e.g., 11%, 13%, 15%, 17%– Select cement content which yieldsappropriate strength



View Of Casting First Lift OfView Of Casting First Lift OfCylinder Using ASTM C1435Cylinder Using ASTM C1435



Completed Test CylindersCompleted Test Cylinders



Strength vs. Cement ContentStrength vs. Cement Content

4,000

4,500

5,000

5,500

6,000

6,500

10% 12% 14% 16% 18%

Cement Content

2 8 - D a y C o m

p r e s s i v e

S t r e n g t h

( p s i )



Sample RCC Mix DesignsSample RCC Mix Designs

Units

Port of Tacoma

Intermodal Yard

Brownsvil le, TX

Border Station

Coarse Aggregate lb/cy 1,700 1,287 (#67 river gravel)

Fine Aggregate lb/cy 1,700 1,762 (concrete sand)

Maximum Size

Aggregate in 5/8 3/4

% Finer Than #200 % 3 - 7 2Cement lb/cy 450 504

Fly Ash lb/cy 100 0

Water lb/cy 257 185

Unit Weight lb/cf 154.3 147.2

Compressive: 3 day psi 1,810 3,046

Compressive: 28 day psi 6,050 4,946

Flex ural : 3 day psi 525 493

Flexural: 28 day psi 770 638



Thickness Design of RCCThickness Design of RCCPavementsPavements

• Design methods based on CTL andCOE Research

• Follows rigid pavement designstrategies

• Plain, un-doweled, un-reinforcedconcrete pavement



RCCRCC -- Unique LoadingsUnique Loadings

• Highway loadings just the start• Industrial pavements present design

challenge– Container and log sort yard loadingscan greatly exceed highway loadings

– 18,000 vs 220,000+ lb. axle loads



Slab Tensile Stress is CriticalSlab Tensile Stress is Critical

Stress is affected by:• load

• tire pressure and spacing• slab thickness• subbase support• concrete stiffness



Design for Stress RatioDesign for Stress RatioStress Ratio = critical applied tensile stress

Modulus of Rupture (flexural strength)where:

critical applied stress is the maximum tensile stress at the

bottom of the concrete pavement slab

and the

odulus of Ruptureis the tensile strength of a concrete beam

tested using third-point loading at 28 days

Flexural (tensile) strength controls for RCC pavements



Thickness Design ProcedureThickness Design Procedure

RCC pavement thickness is increaseduntil the desired stress ratio is

reachedor

the strength of the concrete isincreased



Design AssumptionsDesign Assumptions

• Interior loading• Monolithic slab action for multi-layer

construction

• Load transfer across joints/cracks

• Conservatism:

– Design curve below fatigue tests– Strength gain with age




1. Support strength of subgrade (k value)2. Vehicle characteristics

– Wheel loads

– Wheel spacing– Tire characteristics

– Load repetitions during design life

3. Flexural strength

4. Modulus of Elasticity




• Subgrade Support– “k” value

– Use plate load test, or estimated

relationships• Vehicle Loads

– Normally, heaviest wheel load controls

– Contact area: wheel load/tire pressure

– Wheel spacing: per manufacturer



Software DemonstrationSoftware Demonstration



Single Axle – Single Wheel



Design ExampleDesign Example

• Passenger Car, Single Axle - Single Wheel• Axle load: 2k - Wheel load: 1k• Subgrade k value: 210 pci• Tire pressure: 35 psi• Tire contact area 1,000/35 = 29 sq in• RCC flexural strength: 600 psi• RCC modulus of elasticity: 3,500,000 psi• Load repetitions/day = 35; therefore,

20 years: 35 x 365 x 20 = 255,500



Tandem Axle – Dual Wheel




• Truck, Tandem Axle - Dual Wheel

• Axle load: 34k - Wheel load: 17k• Subgrade k value: 210 pci• Tire pressure: 100 psi• Tire contact area 17,000/100/4 = 43 sq in• RCC flexural strength: 650 psi• RCC modulus of elasticity: 3,000,000 psi• Load repetitions/day = 50; therefore,

20 years: 50 x 365 x 20 = 365,000



Single Wheel




• Straddle Carrier, Single Wheel

• Total load: 104k - Wheel load: 26k

• Subgrade is fine-grained with no subbase

• Tire pressure: 100 psi• Tire contact area 26,000/100 = 260 sq in

• RCC design strength = 7,000 psi

• Load repetitions/day = 20; therefore,20 years: 20 x 365 x 20 = 146,000



for additional information, please visit our website at

www.cement.org/pavements



Thank You!

[email protected]

sca-pca rcc design seminar

Documents