Roller-Compacted Concrete Pavements

Wayne S. Adaska, P.E. Christopher Tull, PE LEED APPortland Cement Association CRT Concrete Consulting, LLC

■ Introduction

■ Mixture Design

■ Thickness Design

■ Construction

■ Ready Mixed Producer Approach

■ Case Studies

Presentation Outline

RCC Guide

■ Introduction

■ Applications

■ Properties

■ Mixture Proportioning

■ Structural Design

■ Production

■ Construction

■ Troubleshooting

www.cement.org/bookstorePCA Booth Number S-12501

SN298

Definition

“Roller-Compacted Concrete (RCC) is a no-slump concrete that is compacted by vibratory rollers.”

■ Zero slump (consistency of dense graded damp gravel)

■ No forms or finishing

■ No reinforcing steel

■ High production

■ Pavers or earth moving equipment

■ Consolidated with vibratory rollers

Concrete placed in a different way!

Multiple Personalities

Concrete

• rigid pvmt

Soils

• Proctor test

• density test

Asphalt

• paver

• rollers

Roller-Compacted Concrete

Benefits of RCC Pavements

■ Fast construction

■ Economical

■ Early load carrying capacity

■ Supports heavy loads

■ Low maintenance

■ Durable

■ Light surface reduces lighting requirements and Urban Heat Island effects

■ Originally used for heavy-duty pavements

■ Growth has accelerated in last seven years

■ Increase in private & non military public use

■ Emergence of asphalt contractors placing RCC

RCC – Experiencing a Revival

Asphalt Prices Have Soared

Base Year: 2002 = 100Source: Bureau of Labor StatisticsLast four months of data are preliminary

Applications

■ Ports, intermodal yards and military hard stands

■ Warehouse facilities

■ Parking areas

■ Maintenance & storage yards

■ Airport service areas

■ Arterial roads

■ Highway shoulders

■ Local streets & intersections

Parking Areas

Honda plant, AL, 2001

207 acresSaturn plant, TN, 1988

134 acres

Parking Areas

Sustainable Contributions■ Reduced export/import/fuel use

■ Less mined and processed materials

■ Reduced excavation

■ Faster construction

■ Cooler pavement

■ Used in-situ materials

■ Less damage to area roads

Subgrade

RCC

Soil-Cement Base

6”-8”

6”12”Crushed

Stone Base

Subgrade

4” Asphalt

Design/Bid Section

As Constructed

BMW, SC, 2009

50 acres

Parking AreasTrailer Employee

Truck

Ohio Turnpike Service Plaza, 2010

30 acres

Project Considerations

■ Project size

■ Site geometry

■ Loading characteristics

■ End use

■ Client expectations

Surface Appearance

■ Not as smooth as PCC

■ Similar to HMA binder course

■ Important to recognize

difference

Mixture Design

Mixture Design

■ Dry enough to support vibratory roller

■ Wet enough to permit adequate distribution of paste

Consistency

Mixture Design

■ Modifications needed in no-slump conventional concrete mixture procedures (ACI 211.3R) because RCC is:

▪ Dryer than zero slump

▪ Not air-entrained

▪ Lower cement content

▪ Higher fines content (up to 8% of non plastic fines)

▪ Nominal max. size aggregate 1/2 to 3/4 in.

Conventional Concrete & RCCPercent by

Volume

Conventional PCC

11 16 6 26 41C.M. Water Air Fine Agg. Coarse Agg.

143 pcf

Roller Compacted Concrete

10 13 1.5 35 40.5C.M. Water Air Fine Agg. Coarse Agg.

153 pcf

Proportioning Methods

■ Several methods available:

■ Concrete consistency method

■ Soil suspension method

■ Optimal paste volume method

■ Soil compaction method

Soil Compaction Method

■ Most common method used in the U.S. for RCC paving mixtures

■ Testing equipment readily available at construction materials laboratories

■ Three major steps

1) Select aggregate blend with minimal voids

2) Determine optimum moisture content and maximum density (modified Proctor test)

3) Determine cementitious content

Step 1: Selection of Aggregate Blend

Step 1: Selection of Aggregate Blend

0

10

20

30

40

50

60

70

80

90

100P

erc

en

t P

asin

g

Sieve Number

RCCP Gradation Band

0.45 Power, 3/4" MS Suggested Lower Limit Suggested Upper Limit

#200#100 #4#16 3/8" 1/2" 3/4" 1"

#50#30 #8

Size NumberPercent Passing

1-in(25 mm)

100

3/4-in (19mm)

90-100

1/2-in (12.5 mm)

70-90

3/8-in(9.5 mm)

60-85

No. 4(4.75 mm)

40-65

No. 16 (1.18 mm)

20-40

No. 100(150 m)

6-18

No. 200(75 m)

2-8

Suggested Blend Gradation

PCA suggested limits

0.45 Power curve

Step 2: Determine Opt. Moisture Content & Maximum Density▪ Select a mid-range cement content (e.g. 12% or

450 pcy)

▪ Perform a modified Proctor test (ASTM D1557)

▪ Construct moisture-density relationship curve

▪ Determine Optimum Moisture Content and Maximum Dry Density

Moisture-Density Relationship

140

141

142

143

144

2% 3% 4% 5% 6% 7% 8%

Dry

De

nsit

y (

lb/

cf)

Moisture Content

Maximum dry density

Optimum moisture

Step 3: Determine Cementitious Content

■ Make and test compressive strength cylinders ■Maintain percent optimum moisture content (use OMC

determined in Step 2)

■Use varying cement content, e.g., 10%, 12%, & 14%

■Mold 3 cylinders at each cement content (ASTM C1435)

■ Select cement content which yields appropriate strength

Strength Testing

Fabricating cylinderswith vibrating hammer

(ASTM C1435)

3000

3500

4000

4500

5000

5500

6000

6500

7000

9 10 11 12 13 14 15

Co

mp

ress

ive

stre

ng

th (

psi

)

Cementitious content (%)

12.7%

Step 3: Determine Cementitious Content

fc required = f’c + overdesign margin of safety

fc

Freeze-Thaw Durability

■ Field performance very good, although not air entrained (PCA publication on Long-Term Performance, RP366)

■ Minor surface paste (1/16”) erodes, then stabilizes

■ RCC results variable under ASTM C666 (F-T) and C672 (Deicer scaling)

■ Conventional concrete tests appear to be too severe based on actual experience

■ Durability tests used for concrete masonry units (ASTM C1262) and precast paving units (ASTM C936) possibly more appropriate

Freeze-Thaw Durability

Thickness Design

Thickness Design of RCC Pavements

■ Follows rigid pavement design methods

■ Plain, undoweled, unreinforced concrete pavement

■ Pavement thickness is a function of:

▪ Design life (load repetitions)

▪ Type of vehicle loading

▪ Engineering properties

▪ Base and subgrade characteristics

Typical Engineering Properties

■ Compressive Strength (f’c)

▪ 4,000 to 6,500 psi

■ Flexural Strength (MR)

▪ 500 to 1,000 psi

▪ MR = C (f’c)1/2 where C ranges from 8 to 12

■ Modulus of Elasticity (E)

▪ 3.5 to 6 million psi

▪ E = CE (f’c)1/2 where CE ranges from 57,000 to

67,000

Design Considerations

■ Structural behavior similar to unreinforced, undoweled conventional concrete pavements

■ Reduced shrinkage as compared to PCC

■ Monolithic slab action for multi-layer construction

■ Load transfer across joints/cracks

■ Thickness

■ 4-inch minimum lift

■ 10-inch maximum single lift

Thickness Design Procedures

■ Heavy duty pavements (loaders, haulers, tanks)

■ PCA design procedure (RCC-PAVE)

■ U.S. Army Corps of Engineers procedure

■ Mixed roadway vehicle traffic (cars, trucks)

■ ACI 330 and ACI 325

■ ACPA StreetPave*

■ AASHTO 1993 (WinPas)*

*When using these programs, increase reliability by 5%

PCA Design Procedure

■ Subgrade support (modulus of subgrade reaction, k)

■ Vehicle characteristics

■ Wheel loads

■ Wheel spacing

■ Tire characteristics (contact area, tire inflation pressure)

■ Number of load repetitions during design life

■ RCC flexural strength, ƒs

■ RCC modulus of elasticity, E

Design Example – PCA Method(From Guide for Roller-Compacted Concrete Pavements)

■ Determine the required RCC

thickness given the following:■ Straddle carrier

■ Axle load = 60,000 lbs

■ Tire inflation pressure = 100 psi

■ k = 100 psi/in.

■ Flexural strength, ƒs = 650 psi

■ E = 4,000,000 psi

■ Load repetitions = 30 per day

■ Design life = 20 yearsSingle wheel

loading

Solution for Design Example

■ For the straddle carrier shown, use single wheel design method

■ Wheel load, P = axle load/2 = 60,000/2 = 30,000 lbs

■ Tire contact area = P/tire pressure

= 30,000/100 = 300 sq in

■ Total design repetitions:■ 20 yr x 365 days/yr x 30 reps/day = 219,000 total reps

■ Determine stress ratio (SR) from Table 5.1 of the RCC Guide:

219,000X

Solution for Design Example

(X – 0.43)/(0.44 – 0.43) = (219,000 – 280,000)/(210,000 – 280,000)

X = 0.438

■ Allowable stress, σ = ƒs×SR

= 650×0.438 = 285 psi

■ Allowable stress per 1000-lb load

= σ / (P/1000) = 285/30

= 9.5 psi/kip

Solution for Design Example

11.5 in.

Determine thickness from Figure 5-3

■ Enter chart (Figure 5-3 in RCC Guide) with tire contact area = 300 sq in.; k = 100 pci; and allowable stress = 9.5 psi/kip

■ Slab thickness of 11.5 in. is required

RCC-PAVE Computer Program

■ Pavement evaluation or thickness design

■ Interior or edge loading

■ Standard vehicle and user defined loading options

■ Developed for heavy-duty pavements with less than 700,000 total load repetitions

■ PCA RCC-PAVE Program available at www.cement.org/bookstore

MC043

Construction

Construction Procedures

■ Test section

■ Subgrade preparation

■ Mixing process

■ Transporting

■ Placing

■ Compacting

■ Curing

Test Sections

■ Train contractor and testing personnel

■ Demonstrate workability and

appearance of mix

■ Demonstrate equipment capabilities

■ Demonstrate construction details

■ Joints, bonding, compaction, etc.

■ Develop rolling requirements/pattern

■ Test RCC and develop correlation

factors for density and f’c vs. MR

Subgrade Preparation

■ Must be firm

■ Check with proof roller or compact to 95% min. density

■ Replace unsuitable materials

■ Shape to proper lines and grades

Continuous Pugmill

■ High-volume applications

■ 125 to 250 + cy/hr

■ Excellent mixing efficiency

■ Mobile, erected on site

Central Concrete Batch Plant

■ Highly accurate proportioning

■ Local availability

■ Smaller output capacity

■ Longer mix times than conventional concrete

■ Possibly more cleaning

■ Dedicated production

Dry Concrete Batch Plant

■ Highest local availability

■ Very good for small jobs

■ 2-step process■ Feeds transit mixers■ Discharge into dumps

■ Mix 60 -70% capacity

■ Low production

■ Segregation concern

Dry Concrete Batch Plant

■ Supplementary mixer can aid in thorough mixing and plant throughput.

Transporting

■ Rear dump trucks normally used

■ Minimize transport time

■ Covers required for long hauls, or hot/windy conditions

Placing

■ Production should match paver capacity

■ Layer Thickness■ 4” minimum thickness

■ 9” – 10” maximum thickness

■ Timing Sequence■ Limited time (generally 60 minutes max.) for

placement of adjacent lanes to maintain “fresh joint”

■ Multiple lifts placed within 60 minutes for “fresh joint”

Placing Equipment

Conventional asphalt pavers

■ Provide some initial density (80-85%)

■ Thicknesses < 6 in.

■ Relatively smooth surface

■ May require some equipment modification

Placing Equipment

High density pavers Vibrating tamping

screed

High initial density, 90-95%

Less roll-down

Thicknesses < 10 in.

High-volume placement (1K to 2K cubic yards per shift)

Compaction

■ Proper compaction is critical for strength and durability

■ Compact to 98% Modified Proctor (ASTM D1557)

■ Vibratory roller

■ Pneumatic tire or rubber coated steel drum to smooth surface

Compaction Very Important

Edge Compaction

Compaction shoe

Edges Critical to Performance

■ Compaction more difficult

■ Segregation more likely

■ Try to minimize number of cold joints

■ Care needed to match grade from cold to fresh joint

Fresh Joint

Running Cold Joints

Curing

■ EXTREMELY IMPORTANT

■ Water or concrete curing compound

■ Application rate depends on surface texture

More Information

www.cement.org/pavements

RCC from a Ready

Mix Producer’s

Perspective

Water Content

• Different!

• Water cement ratio is not important or

designed to.

• Water content determined by the required

compaction.

• Seems like a small window, but it can be

done.

Soil Compaction Method

• Determine moisture content

– Construct moisture/density curve

– Modified proctor ASTM D1557

– Assume a median cement content (e.g. 15

percent)

130

135

140

145

150

155

160

3.0% 4.0% 5.0% 6.0% 7.0%

Den

sity

(p

cf)

Moisture Content (%)

Moisture Density Relationship

Dry Density Wet Density

Modified Proctor

How Much Water?

• Add Total Dry Weights

– Cement

– Supplementary cementitous

– Dry fine aggregate

– Dry coarse aggregate

• Multiply by the optimal moisture content

Water Tolerance

• Is it too tight?

• It is tight, but not too tight.

• Compaction in the field must be 98% of the

optimal wet density.

• Too dry or too wet, it is not physically

possible to get the required compaction.

130

135

140

145

150

155

160

3.0% 4.0% 5.0% 6.0% 7.0%

Den

sity

(p

cf)

Moisture Content (%)

Moisture Density Relationship

Dry Density Wet Density

Modified Proctor

Moisture

Window

Can We Do It?

Low End Optimal High End

pounds/cy 47 63 87

Gallons/cy 5.6 7.6 10.4

+/- 2 gallons (ish)/cy

RCC VIA

READY MIX

PROJECTS

UNION COUNTY

Clifton Rd

Union County

Wanda Hartman &

Southeast Cement

Association RCC Seminar

She believed it could be

done with local equipment

Teamed with IMI & Union

County Crews

Union County

• Project was completed

quickly.

• We did not have a proctor

• We did make some cylinders

• Wanda calls it “White Cold

Patch”

Useful Information… But?

Can we obtain enough

compaction through a

conventional county owned

asphalt paver and roller?

HENRY COUNTY

Access Rd

Henry County

• Perform a test pour at

Buster’s landfill access road

• Do a full scale analysis of

the system

Batching

• Buster’s older plant in New Castle

• Placed into ready mix truck

• Transported into Dump trucks

READY MIX TO DUMP

TRUCK

DUMP TRUCK TO JOBSITE

CHECK DEPTH OUT OF THE

PAVER

DENSITY OUT OF PAVER

CALIBRATED TO PROCTOR

ROLL WITHOUT AND WITH

VIBRATOR ON

DENSITY AFTER ROLLING

Lift

(in)

Wet

Density

(pcf)

Dry

Density

(pcf)

Moisture

(%)

Proctor

(%)

Roller

(y/n)

# Passes

w/o

Vibrator

# Passes

w/

Vibrator

6 117.8 109.7 7.4 74 No 0 0

9 116.1 109.4 6.2 74 No 0 0

6 144.9 136.5 6.2 92 Yes 1 0

6 148.8 138.8 7.3 94 Yes 2 0

8 147.4 137.8 7 93 yes 2 0

8 161.9 151.3 7 102 Yes 2 1

First Run

Lift

(in)

Wet

Density

(pcf)

Dry

Density

(pcf)

Moisture

(%)

Proctor

(%)

Roller

(y/n)

# Passes

w/o

Vibrator

# Passes

w/

Vibrator

6 118.7 111.9 6 76 No 0 0

9 114.4 108.6 5.3 73 No 0 0

6 143.1 135.2 5.8 91 Yes 0 1

9 138.9 131.6 5.5 89 Yes 0 1

9 147.3 138.9 6 94 Yes 0 2

6 153.2 145.2 5.5 98 Yes 0 2

6* 149.0 140.1 6.3 95 Yes 0 2

* Tested at joint

Second Run

Made Cylinders for Compressive Slit Tensile

Comparison

COMPRESSIVE STRENGTH

SPLIT TENSILE

SPLIT TENSILE

GOOD RESULTS

Testing Data(56 day: 28 dry, 28 fog room)

Compressive Load

(lbs)

Stress

(psi)

Sample 1 251,500 8,900

Sample 2 231,380 8,180

Average 241,440 8,540

Split Tensile Load

(lbs)

Stress

(psi)

Sample 1 86,620 765

Sample 2 90,125 790

Average 88,373 778

Split Tensile = 8.4 *√Compressive

CITY OF INDIANAPOLIS

Coolridge

Rd

DAVIESS

COUNTY

200E from 650S to 675S

Dry Batch

Conventional Paver

Roll Down

Fresh Joint

Rolling Fresh Joint

350N from 450E to 575E

Twin Shaft Mixer on Same Plant

Surface Texture

High Density Paver

Moisture Control

Curing

CONLUSIONS

1. Ready Mix Plants can producer quality

roller compacted concrete

2. County highway asphalt pavers & rollers

can provide enough energy to obtain 98%

of the modified proctor

3. High density pavers have a better surface

appearance

CONLUSIONS5. Small coarse aggregate size make for

tighter surface finish

6. Exposed RCC probably not aesthetically

acceptable in a retain environment: asphalt

surface

7. PCA is providing guidance on how much

“credit” to give the asphalt in a composite

system: not much

PCA Guidance

Don’t Break the Rules…

An Amazing Product

Time for A Short Quiz

QUESTIONS?