Presentation on theme: "Subfloor Evaluation Prior to Installation Understanding the science of concrete slabs prior to installation of moisture sensitive floor covering materials."— Presentation transcript:
Subfloor Evaluation Prior to Installation Understanding the science of concrete slabs prior to installation of moisture sensitive floor covering materials
ASTM F-710 Preparation of Concrete Slabs to Receive Resilient Flooring Determination of suitability of a concrete subfloor for resilient flooring Determination of suitability of a concrete subfloor for resilient flooring Suggested construction methods for concrete slabs Suggested construction methods for concrete slabs Suggested preparation methods of concrete floors for resilient flooring installation Suggested preparation methods of concrete floors for resilient flooring installation
Related ASTM Procedures C 109/C 109M Test Method for Compressive Strength of Hydraulic Cement Mortars C 309 Specification for Liquid Membrane-Forming Compounds for Curing Concrete C 472 Test Method for Compressive Strength of Gypsum Cement D 4259 Practice for Abrading Concrete E 1155 Test Method for Determining FF/FL (Floor Flatness and Floor Levelness) E 1486 Test Method for Determining Floor Tolerances Using Waviness, Wheel Path, and Levelness Criteria E 1745 Specification for Plastic Water Vapor Retarders Used In Contact With Soil or Granular Fill Under Concrete Slabs F 141 Terminology Relating to Resilient Floor Coverings F 1869 Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride F 2170 Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In Situ Probes
General Guidelines of ASTM F-710 Dry, clean, smooth and structurally sound… Surface cracks and control joints should be filled…and provide a minimum of 3000 psi compressive strength in 28 days Expansion joints shall not be filled… Surface must be cleaned… No asphaltic adhesive residues… Shall be smooth and flat…within 3/16” in 10ft.
Testing a Slab per ASTM F-710 Removal of sealers, curing agents, bond breakers otherwise known as the “water drop test” Moisture Testing Moisture Vapor Emissions Rate (MVER) Moisture Vapor Emissions Rate (MVER) In Situ RH (Relative Humidity) In Situ RH (Relative Humidity) pH Testing
Preparation of New & Existing Concrete Subfloors New concrete must be cured and dried and in compliance with resilient floor covering manufacturer requirements Existing concrete must be free from any adhesive residues, clean, dry and in compliance with resilient floor covering manufacturer requirements
Basic Concrete Slab Construction Site evaluation Compressed soil Compressed soil Large aggregate (capillary break) Large aggregate (capillary break) Smaller aggregate Smaller aggregate Moisture barrier specifications 0.010” thick reinforced film 0.010” thick reinforced film Exterior Drainage and Landscaping concerns
ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture- Sensitive Flooring Materials Introduction Introduction Concrete Moisture Basics Concrete Moisture Basics Concrete Moisture Testing Concrete Moisture Testing Concrete pH Testing Concrete pH Testing Floor Covering Adhesive Manufacturers Recommendations Floor Covering Adhesive Manufacturers Recommendations Drying of Concrete Drying of Concrete Vapor Retarder/Barrier Vapor Retarder/Barrier Floor Covering Materials Floor Covering Materials Design and Construction Design and Construction
Introduction “The objective of this document is to reduce the potential for moisture-related problems in both slabs-on-ground and suspended slabs. It provides basic information on the concrete drying process, moisture behavior in concrete, testing for pH and moisture, and vapor retarders/barriers. Based on this information, recommendations for the design and construction of concrete slabs that will receive moisture-sensitive or pH sensitive flooring materials or coatings are presented.”
Concrete Moisture Basics Understanding how water moves through hardened concrete is important in determining: Consequences of the moisture movement; Consequences of the moisture movement; Effectiveness of moisture testing methods; and Effectiveness of moisture testing methods; and Validity of flooring manufacturers’ warranty recommendations Validity of flooring manufacturers’ warranty recommendations
Moisture Sources Water of Hydration Water required to complete chemical reaction Water required to complete chemical reaction Typically considered ~25% of cement by weightTypically considered ~25% of cement by weight Water of Convenience Water used for ease of workability and placement Water used for ease of workability and placement Usually another 25% to 40% of cement by weightUsually another 25% to 40% of cement by weight Moisture Vapor Transmission (MVT) Water of convenience evaporating Water of convenience evaporating 4” slab poured at.50 W/C evaporates >½ gallon per sq ft.4” slab poured at.50 W/C evaporates >½ gallon per sq ft. Water coming up through the concrete from under slab Water coming up through the concrete from under slab
Concrete Curing/Drying After curing and before drying begins, the moisture distribution in a hardened concrete slab is reasonably uniform throughout the member thickness (Hanson 1968). As concrete dries, the amount and distribution of moisture changes (Hedenblad 1997).
Curing/Drying of Lightweight & Normal Concrete Drying profiles differ for normal weight and lightweight concrete; Lightweight concrete takes longer to dry than normal weight concrete; and Normal weight concrete takes less than 90 days and lightweight concrete takes more than 180 days to reach 85% RH at the center of a 6 in. (150 mm) diameter specimen.
Effects of Moisture Movement Warping or Curling Slab curls due to moisture loss Slab curls due to moisture loss Contractor grinds to bring into specification for flatness Contractor grinds to bring into specification for flatness Floor covering or moisture barrier applied Floor covering or moisture barrier applied Concrete Equilibrates Concrete Equilibrates Slab Relaxes and areas ground and now lower Slab Relaxes and areas ground and now lower
Effects of Moisture Movement Joint Bulging Slab poured Slab poured Control Joints cut and due to normal slab shrinkage become “V” shaped Control Joints cut and due to normal slab shrinkage become “V” shaped Patching compounds installed Patching compounds installed Floor covering installed Floor covering installed Slab equilabrates and relaxes Slab equilabrates and relaxes Patching compound compressed out of joint. Patching compound compressed out of joint.
Effects of Secondary Moisture Exposure Concrete slabs, properly prepared and under functional HVAC control typically take 50-90 days to reach moisture levels suitable for “normal” floor covering installation Rewetting resets the dry time clock my several weeks Rewetting resets the dry time clock my several weeks
Concrete Moisture Testing Standard test method, if applicable; Acceptable test methods; Frequency and location of testing; Environment (before and during the test); Surface preparation, if applicable; Responsible testing party; Acceptance criteria; and Interpretation of results.
ASTM Supporting Test Procedures ASTM E 1907, “Standard Guide to Methods of Evaluating Moisture Conditions of Concrete Floors to Receive Resilient Floor Coverings,” ASTM D 4263, “Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method,” ASTM F 1869, “Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride,” ASTM F 2170, “Standard Test Method for Determining Relative Humidity in Concrete floor Slabs Using in situ Probes,” and ASTM F 2420, “Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurements and Insulated Hood.”
Concrete pH Testing Factors effecting pH Testing: Wetting Time Wetting Time Test Kit Components Test Kit Components Carbonation Carbonation Surface Preparation Surface Preparation Water in the flooring adhesive Water in the flooring adhesive
Drying of Concrete Water to Cement ration (w/c) is the main driver for concrete drying
Drying of Concrete Thickness of concrete slab also impacts drying time
Vapor Retarder/Barrier Polyethylene based plastic sheet Maximum perm rating of 0.3 perms (1 grain per ft2/h per in. of mercury pressure.) Placed in direct contact with slab or with a “granular blotter layer” between the sheet and concrete.
Floor Covering Materials Effect of Moisture on Floor Covering Adhesive bond strength
Design and Construction Specifications will usually include clauses related to: Testing; Testing; Moisture mitigation systems; Moisture mitigation systems; Vapor retarder/barrier; Vapor retarder/barrier; Concrete materials and properties; Concrete materials and properties; Curing; Curing; Protection; Protection; Surface preparation; Surface preparation; Repair materials; and Repair materials; and Floor covering adhesives. Floor covering adhesives.