ASTM F2170 - Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes
ASTM F2170 is the go-to standard for flooring and concrete professionals who want to accurately measure moisture content in concrete slabs using relative humidity (RH) testing. Adhering to this standard is crucial for preventing moisture-related flooring issues, as well as the legal and mitigation problems that can arise from excessive moisture.
The standard provides precise guidelines for RH testing methods that must be followed by professionals. While it's important to thoroughly understand the specific requirements of the most recent version of standard F2170, the following ten guidelines can serve as a helpful reference to ensure that the criteria outlined in ASTM F2170 are met. It's worth noting that these requirements apply regardless of the RH testing method being used.
Sample Preparation
Here is a detailed procedure for preparing a concrete floor slab for relative humidity (RH) testing according to ASTM F2170:
Confirm Equipment Specifications: The first step is to ensure that the RH testing equipment you plan to use meets the precise dimensions and requirements outlined in ASTM F2170, Section 6. For instance, each test hole must have a liner that isolates the sensor from ambient conditions, and all sensors must have NIST-traceable calibration. Make sure to carefully read the standard to check for any calibration restrictions that may apply.
Check Calibration: Before proceeding, ensure that the sensors and probes are calibrated and up-to-date. If you're using reusable sensors, the manufacturer should calibrate them at least once a year or more often if they're exposed to conditions that may impact their accuracy. Additionally, all sensors must be calibrated no less than 30 days before use.
Check Site Conditions: According to Section 9 of the standard, both the concrete slab and the ambient air above it must be at service conditions for a minimum of 48 hours before testing. Ensure that the site conditions meet these requirements before proceeding.
Map Sensor Count and Location: The next step is to map out the sensor count and location. ASTM F2170 requires three test holes for the first 1000 ft2 and at least one additional hole for each additional 1000 ft2. Record the total area of the slab and the number of test holes on your report.
Determine Test Hole Depth: The test hole depth is not a fixed depth but must be calculated based on the slab's thickness and the number of drying sides. If the slab is drying from one side only, drill a hole to a depth of 40% of the slab thickness. If it is drying from two sides, drill to a depth of 20% of the slab thickness. The depth is calculated to the bottom of the test hole, where the RH sensor or probe will be installed.
Procedure for RH Testing and Reporting in accordance with ASTM F2170:
Drill and prepare test holes: Each test hole should be drilled to the depth calculated in Step 5 of the Concrete Floor Slab Preparation procedure (section 10 of ASTM F2170) and properly prepared. This includes cleaning debris out of the hole and inserting a fully-lined sensor sleeve in the hole to isolate the sensor from ambient conditions.
Insert RH sensor: Follow the manufacturer’s instructions for inserting sensors into each test hole. Ensure that each sensor is capped and sealed according to the manufacturer’s instructions during the equilibration process.
Map and label sensors: Record the serial number of each sensor and place the corresponding serial number decal on the corresponding test hole on the mapped report.
Equilibrate sensors for 24 hours: Wait for 24 hours to allow each sensor to equilibrate before taking initial readings. ASTM F2170 requires each sensor to equilibrate for at least 72 hours, but some RH equipment has been shown to provide readings within 3% of the final RH value within 1 hour of sensor insertion.
Take RH readings: After the 24-hour equilibration period, take initial readings for each sensor. Record the RH value and verify that the reading does not drift more than 1% over 5 minutes. Readings can be updated at any time, but if using reusable sensors, each sensor must equilibrate for at least one hour in each test hole before taking a reading.
Record readings: Record all RH readings on the mapped report. Include the RH value, test hole location, and date and time of each reading. Verify that the number of test holes meets the requirements of ASTM F2170 for the area of the slab being tested.
Interpret readings: Compare the RH readings to the manufacturer’s guidelines for the specific flooring material being installed. If the RH values are outside of the manufacturer’s recommended range, take corrective action before proceeding with flooring installation.
Provide report: Provide a final report that includes all RH readings, test hole locations, and dates and times of readings. The report should also include the calculation for the test hole depth and a statement that the test was conducted in accordance with ASTM F2170.
