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PosiTector CMM IS Concrete Moisture Meter - In Situ

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Introducing the new PosiTector CMM IS In-Situ Concrete Moisture Meter from DeFelsko- the Measure of Quality

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, this 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.

There are several methods for measuring concrete moisture. Of these, the three most popular are non-destructive electronic meters, anhydrous calcium chloride, and in-situ relative humidity probes.

Non-destructive electronic meters measure the electrical impedance of the concrete, which is related to moisture levels. However, these meters can be affected by other factors such as variations in concrete composition, and the presence of reinforcing materials. ASTM recommends that these instruments be used as a comparator, and not for determining quantitative moisture content.

The anhydrous calcium chloride test involves measuring the increase in weight of salt as it collects moisture from an encapsulated area of the concrete surface. However, significant doubts concerning the accuracy of this test have arisen. There is no practical way to calibrate these kits, they measure moisture only on the surface of the concrete, and they are heavily influenced by ambient conditions.

The new industry standard for measuring concrete moisture is the in-situ relative humidity test, as described in the ASTM F2170 test Method. It involves drilling a hole into the concrete, and using an electronic relative humidity probe to measure the moisture directly in the slab. The in-situ test has a number of advantages of other methods:

Most importantly, in-situ probes directly measure the actual moisture conditions within the concrete- regardless of mix, aggregate types, floor thickness, or surface conditions. Potential sources of error are minimized compared to other methods.

In situ tests also tend to provide a significant savings in testing time and labor versus calcium chloride tests.

Finally, In situ probes can be calibrated with traceability to national standards.

The PosiTector CMM IS In-situ Concrete Moisture Meter is the simple, durable, and accurate way to measure in accordance with ASTM F2170.

Each probe includes a calibration check salt and chamber for storage, and to verify calibration accuracy before testing. Probes feature Bluetooth Low Energy wireless technology to transmit moisture readings to a smartphone or PosiTector Advanced gage body.

The probe runs for up to three weeks on a single coin cell battery, and features an innovate design that doesn’t require separate disposable sleeves or bases. A bright yellow cap seals the test area.

The free PosiTector App makes capturing and reporting in accordance with F2170 easy. Using an iOS or Android smartphone, overlay each probe on a floorplan, and add metadata and notes as required by ASTM F2170. When testing is complete, quickly print a professional PDF report that includes all data required by the standard.    

The PosiTector CMM IS is available in three convenient kits. The Basic Kit contains three probes, check salts and a calibration chamber for measuring areas up to one thousand square feet or 100 square meters. A measuring tape and extraction tool are also included.  

The Complete Kit contains everything from the basic kit, in addition to a vacuum tool for cleaning the hole after drilling, a hard-shell carrying case, and two additional probes for measuring up to three thousand square feet or 300 square meters.  

The Pro Kit contains everything from the complete kit, in addition to a PosiTector DPM Advanced gage, for measuring ambient temperature, and humidity. It can wirelessly receive in-situ humidity and temperature measurements, displaying them alongside the ambient measurements.

The process of measuring concrete moisture in accordance with ASTM F2170 is simple with the PosiTector CMM IS.

The first step is to determine the number of probes required. ASTM requires 3 probes for the first 1000 square feet, and another probe for each additional 1000 square feet. Mapping locations is easy with the PosiTector App- take a photo of your floorplan and overlay probe locations. Ensure that the slab and the ambient air above it are at service conditions for a minimum of 48 hours before testing.

The next step is to verify probe calibration. PosiTector CMM IS probes come complete with a long-form certificate of calibration traceable to NIST. F2170 requires that each probe be calibrated within one year of use.

F2170 also requires calibration to be verified within 30 days of use with a saturated salt solution. Each PosiTector CMM IS probe comes pre-packaged with a saturated salt solution, so verifying calibration is as simple as turning on the probe by unscrewing the cap and inserting a battery, then ensuring that the current probe reading matches the label on the container.

Next, drill the test holes. Using a hammer drill and three-quarter inch drill bit, drill to the required depth-  40 percent of the slab thickness if it is drying from one side only, or 20 percent of the slab thickness if it is drying from two sides. Clean any debris from the hole, and note the time the hole was drilled in the app.  

Finally, insert the probe into the hole, and use the yellow cap to seal it. Note the time the probe was inserted using the app.

The probe begins measuring immediately and readings can be displayed at any time using the PosiTector App or PosiTector Advanced instrument.  However, F2170 requires waiting 24 hours for conditions in the hole to equilibrate before measurements are recorded. After that time has elapsed, use the PosiTector Advanced gage body or the PosiTector App to easily record the in-situ temperature and humidity along with the time and date. If the results are outside of project specifications, the probe can be left inside the hole until the project specification is met- probe batteries last up to three weeks.

When testing is complete, simply remove the probe using the extraction tool, and fill the hole with a suitable patching compound.

ASTM F2170 also requires that the ambient temperature and humidity above the hole be measured. Place a probe above the hole, and record conditions using the app.  

The test is now complete, and all data required by ASTM F2170 has been collected. Use PosiSoft Software to download readings from your PosiTector gage body, or press ‘report’ from the PosiTector App to view a PDF inspection report containing all information required by ASTM F2170, which can be emailed or saved.

The innovative PosiTector CMM IS makes the process of concrete moisture measurement simpler, easier, and more accurate. Backed by DeFelsko’s renowned quality, customer service and exceptional two-year warranty, the PosiTector CMM IS is the ideal choice for your concrete moisture measurement needs.