Moisture Content Of Concrete Slab

The second source is moisture rising from below the slab.

Moisture content of concrete 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. Most concrete moisture meters only check surface moisture. Internal relative humidity of concrete slab. Moisture tests for concrete slabs.

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. It is vitally important to test your concrete slab s moisture before installing flooring over it. What you re looking for is moisture condition that s within manufacturer s specifications to accept the flooring product you are going to apply. Concrete slabs often have thicknesses measured in feet not inches.

Why concrete moisture is tested. So you re never going to achieve nor would you want 100 percent dry concrete. Testing with either method will tell you how. The moisture content is then calculated as a percentage of the dry sample weight.

Gravimetric this is a direct and accurate method of determining moisture content by weight in the concrete slab. 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. A definitive test that measures the amount of moisture released from the concrete requires a calcium chloride kit or a relative humidity meter. If excess moisture is present in a concrete slab when an impermeable surface treatment is installed it will become trapped under that covering.

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