Moisture Related Flooring Problems with Concrete Sub-floors

Transcription

1 Moisture Related Flooring Problems with Concrete Sub-floors Presented by: Peter Craig Concrete Constructives Special Program For:

2 How Costly are Floor Moisture Problems Today? It is estimated that the direct and indirect costs associated with moisturerelated problems with concrete floor slabs runs between 300 million and one billion dollars each year in the USA.

3 Types of Moisture Problems with Concrete Slabs

4 Types of Moisture Problems with Concrete Slabs: Blistering & Delamination of Floor Coverings

5 Types of Moisture Problems with Concrete Slabs: Adhesive breakdown

6 Types of Moisture Problems with Concrete Slabs: Expansion of flooring materials

7 Types of Moisture Problems with Concrete Slabs: Mold leading to indoor air quality issues

8 Types of Moisture Problems with Concrete Slabs: Blistering of floor coatings

9 A Classic:

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11 What is the Common Denominator in these Flooring Problems? Moisture Coming from, or Through a Concrete Sub-Floor

12 Identifying the Source of the Moisture

13 Sources of Moisture in a Concrete Slab 1. Moisture originating from within the concrete. 2. Water vapor transmission through the slab. 3. Topical & atmospheric moisture 4. Maintenance.

14 Sources of Moisture in a Concrete Slab: 1. Moisture originating from within the concrete There is always free water (water of convenience) in concrete mixtures with w/c 0.25 or higher.

15 Moisture originating from within the concrete Typical 4000 psi concrete mixture Water-to-cement ratio: 0.50 Mix water: 275 lbs Only about half of the mix water is needed for hydration Which leaves: 1697 lbs of free water in 1000 sq ft of slab area, 4 thick

16 Sources of Moisture in a Concrete Slab 2. Water Vapor Transmission:

17 Somewhere below every building site is water. This water may be near the surface of the earth, or hundreds of feet below. Concrete slab-on-ground Earth Water Table

18 Water (moisture) can migrate upward through the ground, enter and transmit through an unprotected concrete slab by 3 means: 1. Hydrostatic Pressure 2. Capillary Action 3. Diffusion Concrete slab-on-ground Earth Water Table

19 Hydrostatic Pressure Concrete Slab-on-Ground Water Table

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21 Capillary Action Narrow Glass Straw Water

22 Capillary Action

23 Capillary Action Narrow Glass Straw Water

24 Capillary Action Wide Glass Straw Water

25 Diffusion: The passive movement of molecules due to differences in concentration, temperature or pressure. Low concentration - Lower pressure Concrete Slab Soil Water Table High concentration - Higher pressure

26 Below the surface of the earth, water undergoes phase change from a liquid to a vapor and, if unrestricted, migrates upward by the natural process of diffusion and evaporation. Earth Water Table

27 When a concrete slab is placed on the ground, the slab will slow down, but not stop the vertical rise of moisture from below the slab. Earth Water Table

28 For concrete is permeable And its permeability is directly related to is waterto-cement ratio

29 Lower w/c = Lower Permeability Shorter Drying Time Higher w/c = Higher Permeability Longer Drying Time

30 When the surface of the slab is covered with a non-breathing material, the relative humidity in the ground below the slab will reach 100%. This will occur regardless of where you are in the country, or how deep the water table is. Flooring Material Earth C: 100% RH Water Table

31 RH testing of base material below a concrete slab-on-ground PVC pipe 99% RH

32 As the relative humidity in the ground below the slab increases, so will the moisture level within a covered concrete slab-on-ground that is unprotected from below. Concrete internal relative humidity increased Flooring Material Earth C: 100% RH Water Table

33 The most effective means of protecting moisture-sensitive flooring materials, and the buildings' interior environment from the damaging affects of moisture migration from the ground is to install a low-permeance vapor retarder in direct contact with the underside of the slab. Vapor Retarder Flooring Material Earth C: 100% RH Water Table

34 Why does the vapor retarder need to be in direct contact with the underside of the slab? Vapor Retarder Earth C: 100% RH Water Table

35 If a small hole or tear is present in a vapor retarder that is in direct contact with the underside of the slab, the affected area is very small. Vapor Retarder Earth Puncture C: 100% RH Water Table

36 However if the vapor retarder is placed below a layer of sand or granular fill, and a tear or puncture exists, water vapor will enter the fill layer and is free to travel anywhere beneath the slab. Gradually the fill layer will reach a state of very high relative humidity which in turn can increase the moisture level in the concrete slab above. Vapor Retarder Fill layer RH% increases High RH % Earth Puncture C: 100% RH Water Table

37 Sources of Moisture in a Concrete Slab 3. Topical & Atmospheric Moisture:

38 Rainfall

39 In addition to being a conduit for moisture, placing any type of fill material over the vapor Fill retarder Course places the Over fill layer Vapor at risk of Barrier/Retarder taking on water from topical sources Rainfall

40 Fill Course Wet, saturated Over fill layer Vapor above Barrier/Retarder the vapor retarder Wet fill

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43 Water tightness of structure

44 Concrete will lose, or take on moisture based on its ambient surroundings. Therefore, ambient conditions significantly affect the drying time of conventional concrete slab mixtures. Which means that natural drying of slabs in many parts of the country, or times of year, can be a real challenge. For damp clothes on a damp day don t dry

45 Sources of Moisture in a Concrete Slab 4. Maintenance

46 Other Potential Sources of Moisture in a Concrete Floor Slab. Irrigation: Broken Pipes: Condensation:

47 Dew Point Condensation Relative Humidity 90 % 80 77

48 Data Logging of Concrete Surface Temperature and Ambient Conditions

49 Moisture Testing of Concrete Sub-floors

50 Moisture Testing Methods Qualitative Quantitative - Plastic Sheet - Mat Bond Test - Electrical Resistance - Electrical Impedance - Moisture Vapor Emission Rate - In-situ Relative Humidity - Surface Relative Humidity

51 Qualitative Techniques

52 18 18 Up to 8 lbs

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54 How many pounds of water does it take to show up as droplets beneath the poly? Up Up to to 138 lbs lbs

55 Electrical Resistance Relative Scale Readings affected by presence of alkali, carbonation & chlorides

56 Electrical Impedance - ASTM F2659 Useful for relative comparisons, mapping, selecting sites for further tests

57 Quantitative Techniques

58 ASTM F1869: MVER Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride

59 ASTM F2170: Slab Humidity Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes

60 ASTM F2420: Surface Humidity Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood

61 What MVER moisture tests tell you: Determines the amount of moisture emitting from the top ½ to ¾ of the concrete

62 MVER comes from how deep in the concrete? CTL MVER Uptake Study CaCl2 kit, dish on balance pan 4 in. concrete slab (0.4 w/c) with sealed surfaces RH probes to datalogger Balance weighs CaCl2 dish Courtesy of CTL

63 MVER comes from how deep in the concrete? CTL MVER Uptake Study CaCl2 kit, dish on balance pan 4 in. concrete slab (0.4 w/c) with sealed surfaces RH probes to datalogger Balance weighs CaCl2 dish Courtesy of CTL

64 MVER comes from how deep in the concrete? 0 10 Depth from Top of Slab, mm % of the measured MVE comes from the top 12 mm (1/2 in.) of concrete CaCl 2 kit does not detect moisture below 20 mm (3/4 in.) deep Courtesy of CTL Percent of Total Measured MVER

65 Calcium Chloride MVER Testing is an indicator of moisture in the top ½ to ¾ of the concrete only..

66 Properly conducted, the test does provide useful information, however the results do not tell the whole story

67 Unmeasured source of moisture

68 MVER Testing Procedure Concrete surface must be dry vacuum ground prior to installed of the test kit.

69 MVER Testing Procedure Calibrate gram scale Weigh test dish of calcium chloride with tape on and record weight

70 MVER Testing Procedure Remove sealing tape on dish and tape to underside of dome Twist and remove lid, invert, and place below dish Do not spill any calcium chloride! Place dish in the center of test area Immediately place plastic cover over dish Make sure seal is air tight Record date, start time & ambient conditions

71 MVER Testing Procedure Wait 60 to 72 hours Check calibration of scale Open plastic cover by cutting Don t t spill any calcium chloride Replace lid on dish and reseal with original tape Reweigh immediately Record new weight, date, time and ambient conditions

72 MVER Testing Procedure Calculation of MVER 1. Determine weight gain of dish 2. Multiply weight gain by the area beneath the dome less the surface area of the dish 3. Divide by the number of exposure hours Example: Starting weight 31.0 grams, ending weight 35.0g, = 4.0 grams 4.0 x hours = 6.7 lbs/1000sf/24 hrs

73 Significance and use: Provides an MVER value expressed in pounds/1000 square feet/24 hours Limitations: MVER Testing Procedure Only reflects condition at time of test Only reflects condition in upper ½ to ¾ inch of the slab

74 Concrete Internal Relative Humidity Testing ASTM F 2170

75 What in-situ RH moisture tests tell you: Determines, or predicts the moisture level throughout the slab, top to bottom 40% of slab thickness Concrete slab-on-ground

76 ASTM F2170: Concrete internal relative humidity RH% Ambient Conditions 70 F - 50% RH RH% Concrete Placement

77 ASTM F2170: Concrete internal relative humidity RH% Ambient Conditions 70 F - 50% RH RH% Concrete Drying Profile Over Time

78 ASTM F2170: Concrete internal relative humidity RH% Ambient Conditions 70 F - 50% RH RH% Floor Covering Installed

79 ASTM F2170: Concrete internal relative humidity RH% Ambient Conditions 70 F - 50% RH % 40% of slab thickness Moisture Redistributes Within Slab

80 In-situ RH Testing Procedure Apparatus: Humidity probe and digital meter

81 In-situ RH Testing Procedure Apparatus: Humidity probe and digital meter Hole liner

82 In-situ RH Testing Procedure Apparatus: Humidity probe and digital meter Hole liner Rotary hammerdrill

83 In-situ RH Testing Procedure Apparatus: Humidity probe and digital meter Hole liner Rotary hammerdrill Vacuum cleaner

84 In-situ RH Testing Procedure Apparatus: Humidity probe and digital meter Hole liner Rotary hammerdrill Vacuum cleaner Brushes

85 In-situ RH Testing Procedure Calibration of equipment: Calibration of the probes should be checked before and after every investigation.

86 In-situ RH Testing Procedure Calibration of equipment: Calibration of the probes should be checked before and after every investigation. Recording instrument should be checked by the manufacturer at least on an annual basis.

87 In-situ RH Testing Procedure Test depth: Drying from top only: 40% of slab thickness

88 In-situ RH Testing Procedure Test depth: Drying from top only: 40% of slab thickness Drying from top and bottom: 20%

89 In-situ RH Testing Procedure First locate embedded items Drill dry to required depth assure that hole is vertical

90 In-situ RH Testing Procedure First locate embedded items Drill dry to required depth assure that hole is vertical Remove dust from hole

91 In-situ RH Testing Procedure First locate embedded items Drill dry to required depth assure that hole is vertical Remove dust from hole Insert hole liner

92 In-situ RH Testing Procedure First locate embedded items Drill dry to required depth assure that hole is vertical Remove dust from hole Insert hole liner Wait 72 hours

93 In-situ RH Testing Procedure First locate embedded items Drill dry to required depth assure that hole is vertical Remove dust from hole Insert hole liner Wait 72 hours Insert probe

94 In-situ RH Testing Procedure Measurement: Allow to reach equilibrium, <1% drift in 5 min

95 In-situ RH Testing Procedure Measurement: Allow to reach equilibrium, <1% drift in 5 min Take measurement

96 In-situ RH Testing Procedure Measurement: Allow to reach equilibrium, <1% drift in 5 min Take measurement Remove liner and patch hole

97 In-situ Concrete RH Equipment Study Location: W.R. Grace Labs Cambridge, Massachusetts

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99 ASTM F 2170: Slab Humidity Hole Liners

100 Test Series III Universal Hole Liner Universal Sleeve

101 Universal Hole Liner Universal Sleeve / Volume Test 1 in. OD PVC pipe Sensor Series III 3/4 in. ID Epoxy seal 1.6 in. 5/8 in.

102 Universal hole liner test Universal Hole Liner

103 Test Results

104 Universal Hole Liner Universal Position / Volume Test Sensor Series III 3/4 in. ID PVC pipe 72 hour edited readings 1. 85% 2. 72%* 3. 83% 4. 84% 5. 82% 6. 83% 7. 82% 5/8 in. *Test directly over coarse aggregate particle

105 What We Learned 1. In-situ RH measurements become far more consistent when the hole liner/sleeve completely isolates the side walls of the drilled hole from the bottom of the drilled hole. 2. In-situ RH measurements are more consistent when the moisture entrance area of the probe is near the bottom of the drilled hole and captured air is not allowed to escape along the sides of the probe.

106 What Needs to Happen 1. All hole liners/sleeves must be designed to be truly depth specific. 2. Probes need to be designed such that the measurement of moisture takes place near the bottom of the drilled hole. 3. Inserted probes must be capable of creating a sealed chamber of air at the bottom on the hole liner/sleeve such that air is not free to escape along the exterior sides of the probe.

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109 Sensor Stabilization Time Study Objective: To determine how long it takes the various sensors to reach equilibrium RH within their respective sleeves that have been in place for a minimum of 72 hours

110 Sensor Stabilization Time Study 1. Sensors removed after 72 hour readings. 2. Sleeves capped 3. Sensors re-installed 3 days later with readings taken every 15 minutes for 3 hours

111 Sensors removed sleeves capped

112 Elapsed Time Sensor Stabilization Time after Removal and Re-insertion Slab 1 - Normalweight Control - w/c 0.45 Slab 7 - Normalweight w/admix - w/c 0.50 Slab 13 - Lightweight Control - w/c 0.55 Sensor (minutes) hour Hours Hours Previous 72 Hour Reading Sensor #: Point when 3 successive readings are identical - minimum 30 minute span Point where reading is within 1 point of the 3 hour reading if sooner than 3 identical successive readings are reached

113 Sensor Stabilization Time Study Study conclusion: On average after insertion it will take approximately one hour for sensors to reach a state of equilibrium RH with the drilled hole

114 MVER & RH are Complementary While there is no direct relationship between MVER and insitu RH both pieces of information can be helpful MVER = moisture near the slab surface %RH = Moisture level within the slab However An MVER measurement alone is insufficient information to base a flooring installation upon!

115 Concrete Surface Humidity ASTM F 2420

116 ASTM F2420: Surface Humidity Often referred to as the Hood test

117 What surface RH moisture tests tell you: Surface RH Testing: Non-evasive means of determining slab RH level

118 When the concrete sub-floor moisture levels are too high How do you fix it?

119 First establish if the concrete sub- floor is flat and level

120 Slab Curl Curling Vapor Barrier / Retarder Differential Drying Shrinkage Drying from the Top Down

121 There however is another side of curl Reverse The other Curl side of Curl

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124 Flooring Installed Moisture Re-Distributes

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126 How do you correct a curled slab Rigid Foam or Polyurea Stabilization

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128 Rigid Foam or Polyurea Stabilization 3/8 or 5/8 dia grout holes Void

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130 Rigid Foam or Polyurea Stabilization 3/8 or 5/8 dia grout holes Rigid foam grout

131 Rigid Foam or Polyurea Stabilization Re-drill with 5/8 or 3/4 bit Rigid foam grout

132 Rigid Foam or Polyurea Stabilization Patch drill holes Rigid foam grout

133 Grind Down Curl

134 1. Establish if an effective, low-permeance vapor retarder is present directly below the slab. 2. If a vapor retarder is present directly below the slab, identify the material, evaluate its physical condition, and review its physical properties for conformance with the project specifications, flooring manufacturers requirements and ASTM E1745.

135 How to make the determination: Dry core through the slab Vapor Retarder?

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137 Effective Vapor Retarder Directly Below Slab

138 Repair of the Vapor Retarder After Coring: Shape a double thickness of aluminum foil to the circumference of cored hole

139 Repair of the Vapor Retarder After Coring: Install adhesive gasket strip around base of cored hole.

140 Repair of the Vapor Retarder After Coring: Place preformed aluminum vapor retarder replacement section onto adhesive gasket

141 Repair of the Vapor Retarder After Coring: Patch core hole with rapid setting concrete patch

142 Strategies for Correcting Moisture-Related Flooring Problems Moisture Mitigation

143 What is Moisture Mitigation for a Concrete Slab? Moisture Mitigation for a concrete slab is a treatment or method intended to correct an unacceptable moisture- related slab condition either before or after a flooring or coating problem develops.

144 What is Moisture Mitigation for a Concrete Slab? Moisture Mitigation is intended to both reduce moisture transfer from the concrete and to protect the flooring material or coating from the effect of long-term exposure to moisture-induced induced high ph levels.

145 There are Two Levels of Moisture Mitigation Level 1 Level 2

146 Level 1 Moisture Mitigation: 1. New construction with an effective vapor barrier / retarder Closed Slab System Vapor Emissions Effective Vapor Barrier / Retarder or Metal Decking System need only suppress moisture originating within the concrete.

147 Level 1 Moisture Mitigation: For level 1 conditions, most corrective options can be considered provided that the MVER levels upon which the warranty is based are determined by testing in the un-vented manner.

148 Level 2 Moisture Mitigation: 2. Existing structures or new construction without an effective vapor barrier / retarder Open Slab System Moisture Emitting from the concrete No Vapor Barrier Moisture Transmitting through the concrete

149 Level 2 Moisture Mitigation: For level 2 conditions, only systems that have no moisture or ph limits should be considered. No Vapor Barrier

150 Corrective Moisture Mitigation Strategies Slab Replacement Slab Capping Accelerated Drying Topical Methods

151 Corrective Moisture Mitigation Strategies Slab Replacement

152 Corrective Moisture Mitigation Strategies Slab Capping Low-permeance vapor retarder over concrete sub-floor

153 Corrective Moisture Mitigation Strategies Accelerated Drying

154 Corrective Moisture Mitigation Strategies Topical Methods Reactive Chemistries Moisture Suppression Coatings Preformed Systems

155 Corrective Moisture Mitigation Strategies Reactive Chemistries Sodium Silicate Potassium Silicate Lithium Silicate

156 Topical Application of Silicate-Based Material

157 Corrective Moisture Mitigation Strategies Moisture Suppression Coatings Hybrid, two-component epoxy systems

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162 Cementitious Blotter Layer Flooring Adhesive Blotter Layer Mitigation System

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169 Preformed Systems Variety of products Use limited to certain types of floor coverings

170 Moisture Mitigation Summary A moisture mitigation system must first be capable of reducing moisture at the concrete /adhesive interface. The system must also be capable of withstanding sustained high ph levels that may develop beneath the system once the floor is covered.

171 The 10 Steps To Avoiding Moisture-Related Flooring Failures

172 Start with Common Sense

173 Step # 1: Understand the slab moisture requirements for the flooring materials to be used on the project and employ the design and construction considerations that will be needed to achieve those requirements.

174 Step # 2: Schedule If the project schedule cannot ensure that sufficient time is available for concrete to dry naturally to the required level, a preemptive approach to moisture mitigation should employed.

175 Step # 3: Below-slab Moisture Protection As it relates to designing a concrete slab-on-ground, the ground must be completely taken out of play!

176 Step # 3: Below-slab Moisture Protection To take the ground out of play: ASTM E 1745 Class A Vapor Retarder Permeance requirement modified to: 0.01 perm, after conditioning

177 Compare physical properties after conditioning tests (ASTM E 154)

178 Step # 3: Below-slab Moisture Protection Vapor Barrier/Retarder must be placed directly below the concrete

179 Step # 4: Slab Design & Concrete Mixture The slab design and concrete mixture should not only meet the structural requirements, but also be designed to minimize drying time, shrinkage and slab curl without compromising the ability to place and finish the mixture. Rapid-Drying Concrete is today an option

180 How does Rapid-Drying Concrete differ from conventional concrete?

181 Rapid-Drying Concrete Standard Concrete Rapid-Drying Concrete Transport X X Pump X X Place X X Finish X X Sets properly X X Reduced MVER Reduced RH Dries within 30 days X X X

182 Conventional Drying Conventional Concrete Dries from the top down. Drying time is related to ambient conditions. Seldom reaches an acceptable level of dryness within the project schedule.

183 Rapid-Drying Concrete Self-Desiccation Dries from the surface and consumes water internally through self-desiccation Uniform drying throughout the depth

184 MVER Testing

185 Concrete Internal RH Testing

186 Curling

187 Continuous reinforcing can help control warping (curling) stresses

188 Continuous reinforcing can help control warping (curling) stresses

189 Step # 5: Finishing Concrete sub-floors to receive flooring materials should be finished to a smooth, but non-burnished finish, free of ridges.

190 Step # 6: Curing Use short-term cover curing methods to hasten slab drying time and provide a concrete surface suitable for the direct application of flooring adhesives. Do not use curing or sealing compounds!

191 Moisture Retaining Cover Cure Dry Wet-strength Curing Paper Low Permeance Vapor Retarder

192 Step # 7: Drying Period Create a watertight environment that will protect the slab from re-wetting as soon as possible.

193 Avoid the use of oil or wax-based sweeping compounds. Sweeping Compound

194 Step # 8: Pre-installation Moisture Testing Pre-installation moisture testing should be performed by an independent 3 rd party retained by the owner. Testing technician(s) should hold a current ICRI Moisture Testing Technician Grade 1 Certification

195 Concrete Moisture Testing Certification Program

196 Test both the Moisture Vapor Emission Rate (MVER) & the Internal Relative Humidity of the Concrete Calcium Chloride Method In-situ Concrete Humidity Test ASTM F 1869 ASTM F 2170 Calcium Chloride MVER Testing Alone Does Not Provide Sufficient Information to Reliably Determine the Moisture-Related Suitability of a Concrete Sub-Floor.

197 Step # 9: If Necessary Mitigate high Slab Moisture Levels

198 Step # 10: Proper Flooring installation

199 A Few Words About Mitigation Warranties Make sure you know what you are getting.

200 A Few Words About Mitigation Warranties Make sure to read the fine print.

201 Put it all together and it adds up to: Success

202 Don t let moisture take a bite out of you, or your business

203 Seminar Content & Article Download Center

204 Thank You! Questions?

205 Moisture Related Flooring Problems with Concrete Sub-floors Presented by: Peter Craig Concrete Constructives Special Program For: