How to measure concrete moisture using the NEW PosiTest CMM Non-Destructive Concrete Moisture Meter, from DeFelsko.
When mixing concrete, water must be added to create a workable mix, and to allow the cement to hydrate and cure. After hardening, much of this water remains as moisture within the porous concrete slab. Over the following months, moisture is slowly emitted from the concrete until it eventually equalizes with the surrounding moisture levels.
When applying flooring materials or coatings to concrete, it is critical to ensure that the moisture level inside the concrete has decreased to acceptable levels. If not, moisture can accumulate below the flooring or coating, causing discoloration, cupping, buckling, blistering, adhesive failure, and mold growth.
Non-destructive meters measure the moisture level in concrete using the principle of electrical impedance.
Their operation is described in international standards such as ASTM F2659. They provide a simple, instant measurement of moisture levels near the surface of the concrete.
Alternatively, to accurately determine moisture conditions throughout the slab, relative humidity probes such as the PosiTector CMM IS can be inserted into holes drilled into the concrete. Watch the video linked below to learn more.
As an instant, non-invasive test, the PosiTest CMM Non-Destructive Concrete Moisture Meter is the simple, durable, and accurate way to measure concrete moisture.
The simple four-button interface makes taking and managing measurements quick and easy:
Use the Power button to turn on the instrument, and return to the measurement screen at any time.
The Memory button allows the current reading to be stored into memory. It can also be used to review previous readings.
The Scale button can be used to toggle between Concrete 0 to 6%, Carbide Method Equivalent, and Relative scales.
The Hold Max button is used to select between Continuous Measurement Mode and two hold modes.
Continuous Measurement Mode is the default mode and continuously updates the display with the current measurement value.
Hold Max Mode displays and holds the maximum reading until the memory button is pressed to save it, or the power button is pressed to discard it.
The innovative Hold Max and Save Mode waits for the reading to stabilize, then automatically saves it into memory and resets the display without needing to press any buttons.
It is ideal for use with the Telescopic Extender Accessory, which threads into the sturdy tripod mount built into the meter. With one hand, quickly measure and record concrete moisture over large areas without the need to bend down or kneel.
The PosiTest CMM uses two AAA batteries providing hours of operation for all day use.
It is capable of storing up to 200 readings, which can be downloaded to the included PosiSoft Desktop software using the built-in USB port.
The rugged PosiTest CMM Concrete Moisture Meter features a weatherproof, dustproof, and water-resistant IP65-rated enclosure, ideal on any jobsite regardless of weather conditions.
A Check Standard is included to verify the meter’s operation and accuracy. Simply place the check standard on a flat, non-conductive surface and press the meter down firmly until the pins are compressed. If the displayed reading is within the range written on the Standard, the instrument is operating correctly.
To take a measurement, both the floor slab surface and ambient air space above the floor slab should be at the temperature and relative humidity expected under normal use for at least 48 hours prior to taking a measurement. Avoid testing in areas in direct sunlight or subject to direct sources of heat.
Ensure that the concrete surface is uncoated and free of dirt, dust, or standing water.
Remove any dust or debris from the underside of the meter—the PosiTest CMM’s pins must make direct contact with the concrete surface to take an accurate reading.
Place the gage onto the concrete surface and press down to fully compress the sensor pins. The sensor pins are designed to measure accurately on smooth, rough, or uneven concrete surfaces.
The moisture measurement will display until the gage is lifted from the concrete surface. Press the Memory button to record the measurement in gage memory.
At each measurement location, the best practice is to take readings several times in close proximity to one another, noting the maximum measurement value. The Hold Max mode makes this process easy.
ASTM F2659 outlines a standardized method for measuring concrete moisture over large areas. Take measurements at eight locations in the first 1000 square feet (100 square meters) and at least five additional locations for each additional 1000 square feet, making sure to measure near exterior walls and other areas with a potential for high moisture levels.
When inspection is complete, use the built-in USB port and included cable to download, view, and print stored readings in professional PDF reports quickly and easily with PosiSoft Desktop.
If other DeFelsko instruments, such as the PosiTector DPM Dew Point Meter or the PosiTector 200 concrete coating thickness gage are used on the same job, measurement data can easily be compiled into one report. Fully customized reports can also be created to match existing paper forms or layouts.
The new PosiTest CMM Concrete Moisture Meter is the Simple, Durable, and Accurate way to measure moisture content in concrete and screed slabs. With an easy-to-use interface, fast measurement speed, memory, and reporting solutions—all backed by DeFelsko’s renowned quality, customer service, and exceptional two-year warranty—the PosiTest CMM is the ideal choice for concrete moisture measurement.