1 singel - rcc intro

7/28/2019 1 Singel - Rcc Intro

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Matthew W. Singel, PE


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DefinitionDefinitionRoller-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!


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RollerRoller--Compacted ConcreteCompacted Concrete


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Engineering PropertiesEngineering Properties

Compressive strength 4,000 to 10,000 psi

Flexural strength

500 to 1,000 psi fr = C(fc)1/2

Modulus of Elasticity

3,000,000 to 5,500,000 psi E = CE(fc)1/2


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AdmixturesAdmixtures Retarders or water reducers can be

used to increase working time Superplasticizers used only in dry batchplant production to reduce mix & off-

load times Air entrainment not used Fibers seldom used, benefits have notbeen demonstratedIncreased difficulty with compactionreported


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Basic Construction SequenceBasic Construction Sequence

Produced in a pugmill or central mixplant or dry batch plant

Transported by dump trucks

Placed with an asphalt paver

Compacted by vibratory and

pneumatic-tired rollers Cured with water or curing compound


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Continuous Pug MillContinuous Pug Mill

High-volume

applications 250 to 500+

tons/hr


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Central Concrete Batch PlantCentral Concrete Batch Plant

Highly accurateproportioning

Local availability

(larger metropolitanareas)

Output for average

size projects(up to 5 acres)


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Dry Concrete Batch PlantDry Concrete Batch Plant

Highest local availability

2-step process Feed into transit mixers

Discharge into dumps

Reduced production Most Flexible - Allows

producer to serviceother customers betweenbatches of RCC


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TransportingTransporting

Rear dump trucksnormally used

Minimize transport

time Covers required

for long hauls, or

hot/windyconditions


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Preparation for PlacementPreparation for Placement

Simple preparation: no dowels, reinforcing,or forms RCC ideal for wide-open, unimpeded

placement runs Block off fixtures (stormwater inlets, etc) Ensure subbase is smooth and at specified

grades

Set up stringlines Moisten subbase prior to RCC placement


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PlacingPlacing

Layer thickness

4 inches minimum 8 inches maximum 10 inches with high-density pavers

Timing sequence Adjacent lanes placed within 60 minutes forfresh joint

Multiple lifts placed within 60 minutes for proper

bonding Production should match paver capacity

Continuous forward motion for best smoothness


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Placing EquipmentPlacing Equipment

High density ABG pavers

Vibrating screed Dual tamping bars

High initial density

(92% to 95%)

Reduces subsequentcompaction

High-volume placement(1000 - 2000 tons/shift)

Designed for harsh mixes

Smoothest RCC surface


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ConventionalAsphalt Pavers Provides someinitial density

(85%-92%) Relatively smoothsurface

Increased cleaningand maintenance


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Aggregate spreaders Jersey spreader Motor grader/dozer Little initial

compaction Low surface

smoothness Poor surface texture Additional surface (or

diamond grinding)required for smoothride


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CompactionCompaction

Proper compaction iscritical for strengthand durability

Compact to 98% of

modified Proctor Vibratory roller Non-vibratory

steel wheel roller Rubber-tire roller


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CuringCuring

Extremely important; ensuressurface durability

Low moisture in RCC

Three methods: Moist cure (7 days)

Concrete curing compound

Asphalt emulsion


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Mother NatureMother Natures Jointss Joints

Most economical 30 to 80 ft spacing

Often first cracks

appear within 24 hours Narrow crack widths

Seal if > 1/8-inch

Best load transfer Minimal raveling


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www.RCCPavement.info


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Thank You!

RollerRoller--Compacted ConcreteCompacted Concrete

Matthew W. Singel, P.E.

1 singel - rcc intro

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