Moisture Content Of Concrete Slab

Every slab of concrete has moisture and will always have moisture.

Moisture content of concrete slab.

Pieces of concrete are removed by chiseling or stitch drilling and dried in an oven to constant weight. What you re looking for is moisture condition that s within manufacturer s specifications to accept the flooring product you are going to apply. Moisture meters can only check the moisture near the surface of a concrete slab which is not sufficient for predicting how the slab will react to having sealant applied or other building materials installed over it. How moisture gets into concrete.

Most concrete moisture meters only check surface moisture. The second source is moisture rising from below the slab. Armstrong recommends conducting a calcium chloride test per astm f 1869 the relative humidity in situ probe test per astm f 2170 or the armstrong 72 hour bond test hygrometer test relative humidity meter placed on floor surface and covered with plastic. If an effective low permeance vapor retarder material is not installed directly in contact with the underside of the slab the concrete will be exposed to a perpetual source of moisture rising from below.

Testing with either method will tell you how. Internal relative humidity of concrete slab. Moisture tests for concrete slabs. Over time hydrostatic pressure will force that moisture upwards and can cause bubbles in surface treatments and cracks in covering materials that are installed above it.

Three methods for testing concrete moisture levels. Concrete slabs often have thicknesses measured in feet not inches. If excess moisture is present in a concrete slab when an impermeable surface treatment is installed it will become trapped under that covering. So you re never going to achieve nor would you want 100 percent dry concrete.

It is vitally important to test your concrete slab s moisture before installing flooring over it. The moisture content is then calculated as a percentage of the dry sample weight.