How Is Moisture Vapor Emission Measured?

Report
2012 ICRI Carolinas Chapter Fall Convention
Coating Failures, Causes, Preventative
Measures & Repairs
Executive Development Center
1241 Military Cutoff Rd #A, Wilmington, NC
RESIDENCE INN FRIDAY OCTOBER 12th 2012
Presented By: Mike Mudrick
Vapor Moisture Transmission
In the Construction Industry
Moisture Activity In Concrete
CAN BE ENCOUNTERED EITHER IN:
•
•
•
•
In Liquid Form
Capillary Action
Hydrostatic Pressure
Measured in psi.
OR
• In Gas Form
• Diffusion Action
• Vapor Static Pressure
• Measured in lb/1000
ft2/24 hr.
• (MVER)
Moisture Vapor Transmission
A COMMON OCCURANCE IN THE FLOORING INDUSTRY
DIFFERENCES BETWEEN
GAS FORM & LIQUID FORM
Vapor Emission (GAS) Pressures:
• Humid gas passing through the capillaries of the concrete
with minimal pressure, very little water, and will dry out
when surface is not covered.
Hydrostatic (WATER) Pressures:
• Generally moderate to high pressure, measured in PSI,
saturates the concrete, moves laterally, and remains
constantly wet.
FLOORING FAILURES DUE TO
MOISTURE VAPOR EMISSION
Acrylic Based VCT Tile Adhesive Failure
Photo courtesy of Construction Technology Laboratories, Inc."
Failure of a Polyurethane Adhesive Due to
Moisture Vapor Emission
Example running track
Failure of an Epoxy Mortar Overlay Due To
Moisture Vapor Emission
Failure of Trowel Down Epoxy Coating Due
to
Moisture Vapor Emission
Failure of Thin Film Epoxy Coating Due to
Moisture Vapor Emission
The Common Denominators?
Probably Could Have Been Avoided!!
All Result In Lost $$$
Increased Liability
GENERALLY SPEAKING
VAPOR EMMISSION PROBLEMS
CAN BE CATAGORIZED IN ONE OF
TWO WAYS
1. Concrete Drying Issues
“Closed Slab or Above Grade Situations”
2. Chronic Diffusion Issues
“Open Slab Situations”
CLOSED SLAB SYSTEM
A Closed Slab System is where an PERMANENT
VAPOR BARRIER or non-perforated metal decking
is in place directly beneath the concrete. In a Closed
Slab System the only source of moisture is freewater originating from within the concrete itself.
OPEN SLAB SYSTEM
An Open Slab System is the most
challenging condition for a topical moisture
& pH suppression system as moisture within
the concrete will typically rise above the
originally tested levels over time.
WHERE
VAPOR EMISSION PROBLEMS
APPEAR
• SLABS ON GRADE
• SLABS ABOVE GRADE
• SLABS BELOW GRADE
SOME COMMON CAUSES OF
VAPOR EMMISSION PROBLEMS
• OLDER BUILDING Without Any Under
Slab Vapor Barrier
• OLDER BUILDING With a Damaged or
Deteriorated Under Slab Vapor Barrier
COMMONLY OVERLOOKED
SITUATIONS LEADING TO
POTENTIAL VAPOR MOISTURE
TRANSMISSION PROBLEMS
• Renovation Or Reconfiguration Of
Existing Space
• NEW CONSTRUCTION With A
Compromised (Direct Contact) V.B.
or
Fill Saturated Before Slab Pour
(Indirect Contact)
GENERALLY IGNORED SITUATIONS
LEADING TO
POTENTIAL VAPOR MOISTURE
TRANSMISSION PROBLEMS
Renovation Or Reconfiguration Of Existing Space
• NEW CONSTRUCTION With Compromised
(Direct Contact) V.B.
• Fill Saturated Before Slab Pour
(Indirect Contact) V.B.
• FAST TRACK/NEW PROJECT:
No Time to Wait for Concrete to Fully Dry
Reasons Achieving Proper RH& or MVER in
New Construction Can Be Difficult
1. Concrete Or Fill Moisture Events
2. WATER Of Convenience In The Fresh Concrete Mix
Amount Of WATER In Fresh Concrete
Example:
A simple 6-sack concrete mix consists of
•564 lb cement/yd3 (Type I, II, …..)
•~3,200 lb aggregates/yd3
•Water for mixing, placing & hydration of cement
•Additives (superplasticizer, air entrainment, etc.)
W/C (water/cement ratio): 0.5 assumed
•Typical Amount of WATER: 0.5 x 564 lb = 282 lb
= 34 gal/yd3
a. Total WATER in concrete
mix = 34 gal/yd3
b. REQUIRED:
WATER for hydration of cement ~35% = 12 gal/yd3
c. RESULT:
~65% surplus WATER needs
to evaporate = 22 gal/yd3
WHAT IS DRY CONCRETE ANYWAY?!?!
Isn’t Concrete Is DRY In 28 Days?
NO!! Concrete Is Only CURED In 28 Days!
Not Acceptable RH%
Not Under 3 to 5 lbs of MVER
Rule Of Thumb For Concrete Drying Time:
AT LEAST ONE MONTH PER 1” OF THICKNESS
(Will More Than Double In Winter)
Lightweight Concrete Mix Designs Dry At Rate 2
Times Longer Than Normal Concrete
ALWAYS TEST TO BE SURE!!!
Concrete Drying Times
How Is Moisture Vapor Emission
Measured?
ASTM F 1869
3 Test Kits For The
First 1000 S/F of
Floor & 1 Additional
Test Kit For Each
Additional 1000 S/F
Example: 7000 S/F
=
9 Total Test Kits
Calcium Chloride Test Kit
CALCIUM CHLORIDE TEST
ASTM F-1869
Measured in Pounds, of the Amount of Water
Emitted from 1000 sq.ft. of Concrete Over 24 hours.
(8 lbs = 1 gallon)
NOT PSI…..
Proper Testing Requires 1 test per 1000 sq.ft. With a
Minimum of Three Tests.
Space MUST Be “Climate Controlled” 48 Hours Prior to Kit
Placement and Conditions Be Stable Throughout the Test.
The Surface Should be Ground, Clean and Remain “Open”
24 Hours Prior to Placement. Tests Require 62 to 70 hours.
Improperly Performed
Calcium Chloride Tests
X
How Is Moisture Vapor Emission Measured?
Another New Test Method Is Currently Being Used:
ASTM F 2170 Test Method For Determining Relative
Humidity In Concrete Floor Slabs Using In-Situ Probes
Pros
Precise, accurate
Can be quickly re-measured
Not AS influenced by
ambient conditions
Cost effective
Easy to track drying
Proven accuracy
Relative Humidity Probes
ASTM 2170
R. H. Probe Hole Depth 40% Of Slab Thickness
5” Thick Slab x .40” = 2 Inches Deep
Drill & Clean Hole, Insert R. H. Probe
Allow R.H. Probe to Acclimate as Required by Manufacturer
Before Obtaining Readings
WHERE
CAN VAPOR EMISSION PROBLEMS
APPEAR?
• SLABS ON GRADE
SLABS ON GRADE
Outdoors
Indoors
WHERE
CAN VAPOR EMISSION PROBLEMS
APPEAR?
• SLABS ON GRADE
• SLABS ABOVE GRADE
SLABS ABOVE GRADE
Structural Concrete Components
Concrete on Non-Vented Metal Deck
Rehabilitation Or Remedial Projects
HOW
DOES VAPOR
EMISSION CAUSE
FLOORING SYSTEMS
TO FAIL?
Moisture Movement
Through Interior Slabs On Grade
VAPOR EMISSION Varies Throughout The Slab Itself
May Also Fluctuate During Different Times Of Year
Moisture Vapor Emission TRANSPORTS
MINERALS & CONDENSATES AT SURFACE
SOLUBLE METAL IONS
• Calcium Hydroxide: “Free Lime”
• Potassium Hydroxide: “Caustic”
• Sodium Hydroxide: “Unstable”
• Result: Dissolved metal ions raise the pH
levels in the “solution” allowing a chemical
attack on the organic compounds.
WHY NOW…. I Never Had
Problems Before?!?!
Volatile Organic Content
REQUIREMENTS CHANGED IN
THE LATE1990’s
The Real Issue Is High Ph
NEW GENERATION OF PRODUCTS DO NOT
PERFORM WELL IN HIGH pH ENVIRONMENTS
pH Scale is Logarithmic
• pH 7 is Neutral
• pH 7 and Lower is Acid
• pH 7 and Higher is Alkaline
• A pH of 13 compared to a pH 7:
1 MILLION Times More Alkaline!!
• Adhesive Warranty Limits: pH 8.2 to 9
How Should One Proceed When MVER Is Not
Within The Required
3 or 5 lbs/24 hr*1000 ft2 or Below 75% RH
•Risk Installing the Floor System?
•Pretend It Is Not A Problem?
•Run Away & Hide?
NO!
APPLY
A QUALITY SURFACE APPLIED VAPOR
SUPPRESANT WHEN:
MVER Is Greater Than 3 or 5 lbs
OR
Relative Humidity % Is Too High
IF HIGH MVER or RH% IS IGNORED
YOU RISK SUFFERING COSTLY
FAILURES & REPAIRS
Various Vapor Suppression Systems
Currently there are 6 major system categories or material methods being marketed to
mitigate a high moisture or pH condition in concrete sub-floors. Treatments range
from single coat applications to multi-stage systems that combine two or more
categories of materials.
1. Reactive Penetrants
Reactive penetrants are fluid applied treatments designed to penetrate the concrete
surface and react chemically with the concrete. The goal of such treatments is to
reduce the moisture vapor emission rate (MVER) and to bind up soluble alkali such
that high pH levels are not experienced at the concrete/adhesive interface.
The most common reactive formulations used for moisture & pH suppression are
based on sodium silicate, potassium silicate or lithium silicate.
Before giving consideration to a silicate-based, reactive penetrant one must have
thorough knowledge of the concrete composition and degree of surface carbonation.
Concrete mixtures that contain pozzolanic materials such as Fly Ash or Slag can
reduce available reactive material within the concrete and thus lead to incomplete
reaction of the silicate-based treatment. Concrete that is more than superficially
carbonated may produce a similar result. Not only will un-reacted silicates not
achieve the desired reduction in the moisture vapor emission rate (MVER) but they
can inhibit the bond of subsequent flooring or coating applications.
Reactive penetrants, as a stand alone treatment, are considered a very high risk
approach to topical moisture and pH suppression.
2. Cementitious Densification
Modified cementitious overlays are intended to isolate the concrete surface from
adhesives or coatings applied above. Such systems are intended to lower moisture
transfer and restrict soluble alkalis within the concrete sub-floor from reaching the
adhesive/overlay interface but can be inconsistent in efficacy.
Various Vapor Suppression Systems
3. Sealers
Fluid applied sealers are available to help reduce moisture transfer and isolate the
concrete from the adhesive applied above. Most sealers have warranty limits between 8 &
12 lbs or less and low ph stability. Therefore sealers should be limited for closed slab
systems where the demands and required performance is limited.
4. Specialty Coatings
Hybrid epoxy-based or epoxy-modified coatings, specifically designed for high
moisture/pH conditions, reduce the Moisture Vapor Emission Rate (MVER) and act
as an isolation barrier to keep solutions of highly alkaline salts within the concrete
from reaching the subsequently applied adhesive or coating.
One, two and three coat systems are available. Some systems may require multiple coats
to achieve sufficient mil thickness on very aggressively shot blasted concrete.
Additional leveling or cementitious substrate material may be required over the
coating. When that becomes necessary the materials and processes to follow should be
approved by the manufacturer of the suppressant system.
5. Dispersement Membranes
Dispersement membranes were historically one of the first approaches to topical
moisture suppression that experienced a reasonable measure of success. Such
systems utilize a special fabric adhered to the surface of the concrete which
provides a lateral avenue for water vapor to diffuse. These membranes are only for
floating systems.
6. Combination Systems
Several companies utilize a combination or “Cocktail” approach where two or more
of the systems discussed above are combined, but this approach is usually cost
prohibitive
DEFICIENCIES OF INFERIOR
SURFACE APPLIED VAPOR SUPPRESSANTS
1. MANY VAPOR SUPPRESSANTS CAN ONLY PROTECT UP
TO 8, 10 or 12 LBS MVER (NOT FOR OPEN SYSTEMS)
2. FEW VAPOR SUPPRESSANTS CAN WITHSTAND 25 LBS
OF MVER
3. STILL LESS ARE 1-COAT SYSTEMS! 2-COAT & 3-COAT
SYSTEMS ARE AVAILABLE….BUT WHY?!?
4. BEWARE!!! MANY DO NOT PERFORM IN HIGH ph
ENVIRONMENTS OF 13 TO 14
5. HAVE MOISTURE SENSITIVE CHARACTERISTICS
Desired Capabilities Of Quality Surface
Applied Vapor Suppressants:
• Must Have Ability To Be Applied To “Fresh” or Old
Concrete
• Must Withstand Constant pH 13 – 14 (Normal pH of fresh
concrete is 12 – 13)
(Aged concrete has a pH 8 – 10)
• Must Provide Proper pH On Surface For Flooring
Applications (Neutral = 7)
• Must Tolerate High or Unknown MVER
• Moisture Insensitive Formulation (Damp Surfaces OK!)
HOW MOISTURE RETARDING EPOXY
COATINGS WORK
V. B.
Epoxy Vapor Suppressant Penetration
Vapor
Suppressant
Thickness
Vapor
Suppressant
Penetration
Microscopy Showing Penetration Of The Vapor Suppressant
STEPS TO SUCCESSFUL
VAPOR SUPPRESSANT
INSTALLATIONS
ALWAYS
Evaluate & Diagnose Existing Floor
TEST FOR SUCCESS
• Extract Core Samples From Both.. Affected &
Unaffected Areas
• Analyze Cores In Lab Under Scanning
Electron Microscope (SEM)
• Analyze Cores Using Ion Chromatography
• Analyze Cores Using Infra Red Spectro
Photometer
Example of Test Cores
Example of Ion Chromatography Test Results
Core #1
Sample Identification
Sample Depth (mm - BTC*)
0-3 mm
IONIC CONSTITUENT
Core #2
3-5 mm
0-3 mm
3-5 mm
CONCENTRATION (ppm)
Sodium (Na)
1410
1090
1160
1140
Potassium (K)
3500
2610
1080
1050
Sulfate (SO4)
2940
4690
3770
2690
Chloride (Cl)
180
110
40
40
Example of Infrared Spectroscopy Test Results
•
Core #1 (MI#28014-01C); 0-3 mm BTC The amount of organic
extractable residue comprises approximately 11,100 ppm (1.110%) of
the concrete mass. The IR spectrum of the residue indicates the
presence of alkyd and polyester resin material.
•
Core #1 (MI#28014-01A); 3-5 mm BTC The amount of organic
extractable residue comprises approximately 8940 ppm (0.894%) of the
concrete mass. The IR spectrum of the residue indicates the presence
of alkyd and polyester resin material.
•
Core #2 (MI#28014-02A); 0-3 mm BTC The amount of organic
extractable residue comprises approximately 16800 ppm (1.680%) of
the concrete mass. The IR spectrum of the residue indicates the
presence of alkyd and polyester resin material.
•
Core #2 (MI#28014-02C); 3-5 mm BTC The amount of organic
extractable residue comprises approximately 9,390 ppm (0.939%) of
the concrete mass. The IR spectrum of the residue indicates the
presence of alkyd and polyester resin material
•
.* Note: ''BTC' = Below the Top surface of the Core
Surface Preparation!
ACID ETCHING?
ABSOLUTELY
NOT!!!
Proper Surface Preparation
Steel Shotblasting
Proper Surface Preparation
Grinding
Proper Surface Preparation
Scarifying
Concrete Surface Profiles
CSP- 2
CSP- 3
CSP- 4
X
CSP- 5
CSP- 6
CSP- 7
CSP- 8
Remove All Contaminants
Degrease If Needed!
Proper Surface Preparation
Remove Excess Water & Puddles
Mix Thoroughly & Spread Suppressant at Prescribed Rate
Back Roll To Assure A Uniform System Mil Thickness
SUCCESSFUL APPLICATION
RECIPE FOR SUCCESS
•
•
•
•
•
Professional Mitigation Team
RH or Calcium Chloride Testing
Select A Quality Mitigation System
Substrate Core Testing
Proper Substrate Preparation
AND
Call On Your Local
ICRI Carolinas Chapter
Professionals
THANK YOU!
QUESTIONS?

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