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. Flooring manufacturers often specify allowable moisture levels before flooring is installed.

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In Situ concrete moisture meter probes are placed within drilled holes in the concrete and measure the relative humidity and temperature within the concrete floor. In-situ probes directly measure the actual moisture conditions within the concrete using precision digital sensors- regardless of mix, aggregate types, floor thickness, or surface conditions. Potential sources of error are minimized compared to other methods, and in-situ sensors can be calibrated with traceability to national standards. Several alternate technologies exist for measuring concrete moisture, each with limitations: 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 absolute 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.

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DeFelsko recommends storing the PosiTector CMM IS probes in the Calibration Check Chamber when not in use. The Calibration Check Chamber and Saturated Salt Solution are designed in accordance with ASTM E104 to maintain a constant relative humidity environment of 75.3% @ 25° C, allowing quick verification of accuracy before use in accordance with ASTM F2170.

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DeFelsko Corporation''s standard 2 year warranty applies.

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A typical battery will continuously power the probe for up to 3 weeks. The battery should be removed when not in use.

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Each PosiTector CMM IS probe is calibrated against known conditions using NIST traceable equipment. A Long Form Certificate of Calibration containing actual measured values is included with each probe.

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