Moisture Testing of Concrete Walls and Floors

Kenneth A. Trimber KTA-Tator, Inc.

Inspection of Cleaning and Painting Webinar Learning Objectives

• Identify the ASTM test methods, instrumentation, and procedures used for determining the moisture content of concrete floors and walls • Define the challenges the industry is facing when assessing moisture content, especially on walls • Describe what SSPC is doing to address the challenges

Sources of Moisture

• Construction practices/curing • Ground water • Joints and leaks • Condensation in wall cavity • Wind-driven rain • Pressure washing • Recognition of sources helps to determine test locations 3

Effect of Entrapped Moisture on Coating Performance

• Reduced Adhesion • Poor Film Integrity • Efflorescence • Blistering • Peeling 4

Standards for Moisture Testing

• Test methods for determining moisture content in concrete are published by ASTM • Most are from Committee F06 on Resilient Floor Coverings

Detection of Moisture in Concrete

• Part 1 – Concrete Floors • Part 2 – Concrete/CMU/Brick Walls 6

Part 1 - Moisture Detection Concrete Floors

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Measuring Moisture Content – ASTM Standards for Concrete Floors

• ASTM F1869-11, Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride • ASTM F2170-11, Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes • ASTM F2420-05(11), the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood Standard Test Method for Determining Relative Humidity on • ASTM D4263-83 (2005), by the Plastic Sheet Method Standard Test Method for Indicating Moisture in Concrete • ASTM F2659-10, Standard Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Other Floor Slabs and Screeds Using Non-Destructive Electronic Moisture Meter • ASTM F710-08, Preparing Concrete Flooring to Receive Resilient Flooring 8

Anhydrous Calcium Chloride (Floors)

• ASTM F1869-11, Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride • Expose known area of bare concrete to known weight of anhydrous calcium chloride for 60 to 72 hours • Weigh the anhydrous calcium chloride before and after exposure • Weight gain is converted to moisture vapor emission rate (MVER) expressed as: lbs moisture/1000 ft²/24 hours 9

Anhydrous Calcium Chloride Testing (con’t)

• Space should be at same temperature and RH as expected during normal use • If not possible, maintain 75° F ± 10°F and 50% ± 10% relative humidity for 48 hours prior to and during testing • Exception – when service environment involves temperature or RH extremes (cold storage room) – use the conditions cited above • 10

Anhydrous Calcium Chloride Testing (con’t)

• All coatings, existing flooring completely removed to bare concrete in a 20”x20” area • Surface roughened by grinding to create a slight profile equal to ICRI CSP1 to CSP2 (added 2011) • Remove all dust • If floor coverings or coatings are removed, need to wait for 24 hours before initiating testing 11

Anhydrous Calcium Chloride Testing (con’t)

• Weigh the sealed container of anhydrous calcium chloride • Remove the lid from the container and center under the dome supplied with the kit – save the blue sealing tape • Firmly seal the perimeter of the dome to the floor • Leave to calcium chloride in place under the dome for 60 to 72 hours • Remove the container, replace the lid, reattach the tape and reweigh to 0.1 gram (lab or field – use same scale) • Use the formula to determine MVER 12

Anhydrous Calcium Chloride Testing (con’t)

• Test Frequency – 3 locations for the first 1,000 square feet – 1 location for each additional 1,000 square feet or fraction thereof • Acceptance Criteria – ASTM F710, Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring recommends a maximum of 3 lb/1,000 ft²/24 hours in the absence of manufacturer’s guidelines.

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Testing with Relative Humidity Probes - Floors

• ASTM F2170-11, Using in situ Probes Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs • Small holes are drilled into the concrete • Sleeves are inserted into the holes and capped • An RH probe (different styles are available depending on the manufacturer) is placed into the hole to obtain a direct reading of the relative humidity 14

Testing with Relative Humidity Probes (con’t)

• Slab and occupied air space above the floor at service temperature and RH for at least 48 hrs prior to testing • Drill holes for RH probes • Hole depth depends on percentage of slab thickness: – If drying from top (e.g., on grade) – 40% of total thickness (1 ½” for 4” slab) – If drying from both top and bottom (e.g., elevated reinforced slab) – 20% of total thickness (3/4” for 4” slab) • Remove dust by vacuuming 15

Testing with Relative Humidity Probes (con’t)

• A sleeve is installed into the hole • Some manufactures also insert a sensor probe at the same time • The sleeve is capped off for 72 hours to achieve equilibrium before testing 16

Testing with Relative Humidity Probes (con’t)

• After the equilibration period, the RH is measured 17

Testing with Relative Humidity Probes (con’t)

• Test Frequency – 3 locations for the first 1,000 square feet – 1 location for each additional 1,000 square feet or fraction thereof – On-grade and below-grade slabs – 1 location within 3 feet of each exterior wall • Acceptance Criteria – ASTM F710-08 (Preparing Concrete Floors to Receive Resilient Flooring suggests max 75% – Finnish and Swedish standards range from 60% to 90% depending on type of covering 18

Relative Humidity of Air Immediately Above the Floor

• ASTM F2420-05(11), Insulated Hood Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and • Insulated hood is used to create an air pocket immediately above the surface of the concrete – the RH within the air pocket is measured by inserting the probe of an RH meter into the hood 19

Relative Humidity of Air Immediately Above the Floor(con’t)

• Hood constructed from rigid thermal insulation with a recessed pocket • Hood lined with vapor-barrier material to isolate the pocket from ambient conditions outside of the hood – must have no permeability • Surface area of air chamber -30 to 40 square inches with a minimum chamber depth of 0.25 inches • Seal to surface with preformed sealant adhesive • (photo from ASTM standard) 20

Relative Humidity of Air Immediately Above the Floor (con’t)

• Slab and occupied air space above the floor at service temperature and RH for at least 48 hrs prior to installing hood • If not possible, maintain 75° F ± 10°F and 50% ± 10% relative humidity during testing • Concrete must be clean and free of coatings, adhesive, and other material • If coverings removed for the test, floor must be exposed to the above conditions for 24 hours before installing the hood • Hood must be completely sealed and remain in place a minimum 72 hours before inserting probe to measure air temperature and RH • Measure ambient temperature, RH, and dew point outside of the hood 21

Relative Humidity of Air Immediately Above the Floor (con’t)

• Test Frequency – 3 locations for the first 1,000 square feet – 1 location for each additional 1,000 square feet or fraction thereof – On-grade and below-grade slabs – test locations must include center of the floor and close to exterior walls • Acceptance Criteria – None in ASTM 22

Common Test Requirements Calcium Chloride, RH probes, RH hood

• Ambient Conditions – As expected in normal use (RH probe/hood – for 48 hrs in advance) – If not possible, 75 ± 10°F; 50 ± 10% RH – for 48 hours in advance – If coverings removed, for calcium chloride and RH hood, wait 24 hours • Test Frequency – 3 locations for the first 1,000 square feet – 1 location for each additional 1,000 square feet or fraction thereof – RH probe – test within 3 feet of each wall; RH hood – also in center • Test Duration – 60 to 72 hours (calcium chloride); 72 hours prior to testing (RH probe and RH hood) 23

Plastic Sheet Test - Floors

• ASTM D4263-83 (2005), Method Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet • The perimeter of an 18” x 18” plastic sheet is firmly taped to the surface • Testing conducted when surface temperature and ambient conditions are within the specified limits for the coating system • Test sites – out of direct sunlight or direct heat 24

Plastic Sheet Test - Floors (con’t)

• After a minimum of 16 hours, examine the concrete and backside of the plastic for signs of moisture • Test Frequency – 1 location per 500 square feet of floor area, or portion thereof • Acceptance Criteria – not stated in the standard, but coatings typically not applied if moisture is visibly present • ASTM F710 Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring describes a procedure that combines the use of moisture meters and the polyethylene sheet test 25

Electronic Moisture Meters - Floors

• ASTM F2659-10, Standard Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Other Floor Slabs and Screeds Using Non-Destructive Electronic Moisture Meter • Relative moisture content of the concrete ½ to 1 inch depth beneath the instrument • Electrical Impedance 26

Electronic Moisture Meters (con’t)

• Slab and occupied air space above the floor at service temperature and RH for at least 48 hrs prior to testing • If not possible, maintain 75° F ± 10°F and 50% ± 10% relative humidity • Concrete must be clean and free of coatings, adhesive, and other material • If coverings removed for the test, floor must be exposed to the above conditions for 24 hours prior to testing • Measure surface temperature within 8 inches of the test locations, and the ambient temperature, RH, and dew point temperature in the vicinity of the test areas 27

Electronic Moisture Meters (con’t)

• Test Frequency (ASTM F2659) – Greater than the calcium chloride and relative humidity methods – 8 locations for the first 1,000 square feet – 5 locations for each additional 1,000 square feet – 1 location within 3 feet of each exterior wall – Each location 1 ft² – 3 to 5 instrument readings per location – record highest • Acceptance Criteria – None in ASTM 28

Electronic Moisture Meters (con’t)

• ASTM F710-08, Preparing Concrete Floors to Receive Resilient Flooring – Addresses many considerations prior to installing resilient flooring, including moisture (anhydrous calcium chloride and RH probes and acceptance criteria) – Appendix X2.5 addresses the electrical impedance test (discussed above in ASTM F2659-10) – Appendix X2.4 discusses electrical resistance test • Electrodes placed on surface, or into 2 pre-drilled holes, 1” deep • Manufacturer may recommend inserting concrete nails into the holes and touching the electrode to the ends of the nails 29

Measuring Moisture Content – ASTM Standards for Concrete Floors

• • • • • • ASTM F1869-11, Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride Standard Test Method for Measuring Moisture ASTM F2170-11, Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes ASTM F2420-05(11), Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood ASTM D4263-83 (2005), Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method ASTM F2659-10, Moisture Meter Standard Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Other Floor Slabs and Screeds Using Non-Destructive Electronic ASTM F710-08, Flooring Preparing Concrete Flooring to Receive Resilient 30

Part 2 - Measuring Moisture Content – Concrete Walls

• The only ASTM standard available is the plastic sheet test (developed by the ASTM D1 Paint committee rather than the F06 Floor Covering committee) • Electronic instruments are used on walls, but there no ASTM standards addressing them 31

Measuring Moisture Content – Plastic Sheet Test - Walls

• ASTM D4263-83 (2005), Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method • Same procedure as described for floors • Frequency is 1 location per 500 ft² of wall area or portion thereof, with a minimum of 1 test for each 10 feet of vertical rise in elevation, starting within 1 foot above the ground 32

Electronic Moisture Meters – Walls Industry Guidance is Needed

• ASTM standards are not available to address moisture testing of walls with electronic instruments. • Guidance is needed to address available instrument options and how they operate, accuracy of readings through existing coatings and on textured surfaces, advantages/disadvantages of each type 33

Moisture Testing of Walls Industry Guidance is Needed

• Pre-test conditioning requirements • Effects of weather (recent rain events) and direct sunlight or shade on the results • Conditions can not be controlled as is the case with floors 34

Moisture Testing of Walls Industry Guidance is Needed (con’t)

• Selecting Test Surfaces: – Block or brick face – Textured or smooth – Mortar joints – Grouted cells – Bond beams 35

Moisture Testing of Walls Industry Guidance is Needed (con’t)

• Test locations and frequency – number and location of readings needed to properly characterize the moisture content 36

Moisture Testing of Walls Industry Guidance is Needed (con’t)

• Test locations and frequency when pressure washing for painting – when is the surface dry enough – could be hours or days • Compare post-wash readings with pre-wash readings – identical locations 37

Moisture Testing of Walls Industry Guidance is Needed (con’t)

• Testing Insulation – Criteria for testing insulation board from interior of building – How to determine the presence of damp core fill insulation 38

Additional Challenges – Walls and Floors Interpretation of Results

• Instruments and methods assess moisture at different locations within the substrate (surface, various depths, entire thickness) • Instruments and methods do not always lead to the same conclusions regarding percent moisture or relative humidity (results are difficult to compare ) 39

Additional Challenges – Walls and Floors Interpretation of Results(con’t)

• • Instruments and methods determine the presence of moisture differently: – Percent Moisture (liquid water) – Relative Humidity (water vapor) 75 to 80% RH equates to a moisture content of ~2% • CCAA* indicates that concrete can be nearly saturated with water and still only register a moisture content of ~5% *Source: Moisture-Sensitive Finishes and Coatings (CCAA) Moisture in Concrete and , published by Cement Concrete & Aggregates Australia 40

SSPC Response to Industry Need for Concrete Moisture Testing Standards

A newly formed SSPC Commercial Coating Committee is developing guides to address Moisture testing of concrete walls, equipment used, test locations and test frequencies, and the interpretation of the Results First draft to be posted on SSPC committee site in August 41

Concrete Moisture Testing Summary

• The surface should be examined for unacceptable levels of moisture prior to painting. Sources of moisture include construction activities, leaks and ground water, condensation inside the wall, and pressure washing for painting • ASTM methods are available for moisture testing of floors, but not walls • It is difficult to interpret and compare results between the methods, and conclusions may differ between methods • SSPC is working to fill the void for standardization by developing a guidance document to address test instruments, test locations, test frequency, and interpretation of results