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The Nuisance & Necessity of Placing ConcreteDirectly on a Plastic Vapor Retarder
Presented By:
Peter Craig Rick Smith Scott Tarr Steve LloydConcrete Constructives Structural Services North S. Tarr Concrete Consulting Lloyd Concrete Services
For Many Years the Nuisance Aspects of Placing Concrete Directly on a Plastic Vapor Retarder were the
Primary Focus of those in the Concrete Industry
Slab Curling (warping)
Dominant Joints
Blistering & Delamination
Longer Finishing Times
Surface Crusting
Shrinkage Cracking
Subsidence Cracking over Reinforcing
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The History and Evolution of Vapor Retarder Location
1981
Typical Slab Concrete Mixture
w/c: 0.40 to 0.60
Slump: 4” to 6”
Nicholson Study
O.697 - 0.753 & 0.801
8” & 9”
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1989
The Blotter / Fill Course Layer
Fill layer
Vapor Retarder
The Blotter / Fill Course Concept
Water Table
Earth
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1993
1996
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By 1998 the Number of Moisture-related Flooring Problems Directly Related to the Fill Course Detail had Increased Significantly
ACI Committee 302 forms a special Moisture Task Group
Earth
Fill layer
C: 100% RH
High RH %
Puncture
Vapor Retarder
Water Table
RH% increases
The Problem with the Blotter / Fill Course Concept
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EarthC:100% RHPuncture
Vapor Retarder
Water Table
Vapor Retarder
Directly Below Slab
By 2001 a shift in thinking began taking place
Concrete International April 2001
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2001
By 2004, ACI 302.1R began to introduce a change in thinking
2004
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By 2006 the directive was clear
Today - ACI 302.1R - 15
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Today
Today much has been learned about the Nuisance & Necessity of placing concrete directly on a plastic vapor retarder
The necessity is real, and doing so is today the industry standard for the design and construction of concrete slabs-
on-ground that will receive a moisture sensitive floor covering or coating.
Up next are three of the concrete industry’s finest who will discus further some of the nuisance and benefit aspects of
placing concrete directly on a plastic vapor retarder and what is being done to successfully mitigate potential concerns
Rick Smith Scott Tarr Steve Lloyd
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Rick Smith
January 1987My First World of Concrete, Houston, TX Astrohall / Astrodome
December 1987Graduated Oklahoma State University with BS in Construction Management Technology
May 1988 ‐ 2000Ribtec
Carbon Steel Sales Manager
Novocon / SI Concrete Systems
Regional Sales Manager, Director of Technical Services
June 2000 – January 2016Structural Services Inc.
29th Consecutive WOC!
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Subbase
Subgrade – 4 to 6” Dense Graded Aggregate (DGA), 3/4” Minus Crusher Run
Concrete
< 15’ OCEW
No Mention of a Vapor Retarder
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Concrete
Isolation Jointaka - Expansion joint
Construction Jointaka - Formed joint
Contraction Jointaka - Control Joint
Strategic ReinforcementSmooth Dowel
Plate Dowel
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Concrete
Smooth DowelPlate Dowel
DeformedReinforcement
FiberReinforcement
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Drying Shrinkage vs Time
Shrinkage & Thermal Expansion / Contraction vs Aggregate Type.
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Slab Warms in Summer and Extrudes Filler out of the Joint
Hone Flush and Fill With Semi‐Rigid Epoxy in Late Winter
Floor Expands, Extrudes Filler Lift Truck Shaves it Flush
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Channel Cuts Narrow & Wide Nosing Repairs
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1, 2, 3 or 4 Deep Pallet Riders 1600‐PSI Contact Pressure
4” Unreinforced Slab on Ground
Plate Dowels at Construction Joints
Joints < 10‐FT OCEW
10‐Mil Vapor Retarder
Poured June 2005
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Non Uniform Joint Activation Faulted Joints
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Cut Out Existing Filler Install and Rake Silica Sand
Fuse with Modified Structural Urethane
Overfill with Semi‐Rigid Polyurea and Shave Flush
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#3 x 36” @ 16 or 18” OC“Hybrid” – Plate Dowels + #3 x 36 @ 24” OC ALTERNATING
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Construction Joint Contraction Joint
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6 & 7‐1/4” Slabs on Ground
Reinforcement#3’s @ 18” OCEW for 6” SOG
#3’s @ 16” OCEW for 7‐1/4” SOG
TX‐DOT 247 Flex Base
Moisture Conditioned
Moisture Injected
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With Vapor Retarder Without Vapor Retarder
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With Vapor Retarder Without Vapor Retarder
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World of Concrete 2016
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To prevent transmitting moisture from the sub grade to the surface of the concrete
Radon gas
Codes
Slip sheet
Finishing operationsCurling
Dominate jointsCracking
Plastic ShrinkageDelamination
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