A concrete moisture meter is a type of

moisture meter Moisture meters are measuring instruments used to measure the percentage of water in a given substance, as physical properties are strongly affected by moisture content and high moisture content for a period of time may progressively degrade a mat ...

used by installers of

flooring Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface. ...

to measure the moisture levels of

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

. These meters have been used for decades to measure the

moisture content Water content or moisture content is the quantity of water contained in a material, such as soil (called ''soil moisture''), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed ...

in different materials and substances. Concrete meters have evolved from the successful wood moisture meter as flooring contractors tried to use their wood meters to measure the moisture in

. Concrete moisture meters are designed to detect moisture to a depth of of a

concrete slab A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ...

in order to avoid the

rebar Rebar (short for reinforcement bar or reinforcing bar), known when massed as reinforcing steel or steel reinforcement, is a tension device added to concrete to form ''reinforced concrete'' and reinforced masonry structures to strengthen and aid ...

reinforcement below the surface. They are designed to be used as a relative test. The meters are used to "'Spot check' the top surface at one particular location on the slab." The results can determine the best place to put a concrete

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

test.

Limitations

There is no

ASTM ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...

standard for using a concrete moisture meter to determine a final moisture content reading. Concrete moisture meters, either non-pin or pin meters are affected by what it sees in the concrete. This can be anything from the

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

of the concrete and aggregate size to the chemical properties of the slab. Uncovered concrete dries from the top down. Concrete moisture meters measure only the top inch at most and this area is drier than the concrete further down. Once a

floor covering Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface. ...

has been installed the moisture in the slab equilibrates. In order to ensure the equilibrated moisture will be a safe level for a floor covering, a relative humidity sensor must be drilled and placed at 40% of the depth of the slab. This depth has been proven to be the relative humidity percentage, that the slab will equilibrate once the top has been covered by a floor covering.

References

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