Spring and fall herald pleasant weather in many areas, with warm days and cool nights. However, the same combination that makes outdoor activities pleasant can wreak havoc in industrial facilities. Temperature and humidity swings create condensation on concrete slab floors common in many industrial settings. Known as "sweating slab," this sheen of water can cause big issues with employee safety and product integrity.
Following are a few of the common questions about sweating slab, and an example of a company that solved its perspiration problem.
What is sweating slab?
Condensation occurs when warm, moist air contacts a cold surface. As the air becomes colder, it loses its ability to store moisture. In the spring and fall, temperature swings and the accompanying condensation on concrete floors can cause problems in workplaces worldwide, resulting in serious worker risk, operational issues and product loss.
What causes sweating slab?
According to Peter Craig, founder of Concrete Constructives, "the two major causes of slab surface sweating are classic dew point and hygroscopic activity outside of classic dew point parameters."
Hygroscopic activity involves substances, particularly soluble salts, in and on the surface of the slab, drawing moisture from the air to the surface of the slab. Dew point related issues occur when the surface of the concrete slab is at or below the saturation point of the air. In the spring, a concrete slab will trail the air temperature by about a month. So while the April air is a balmy 72, the slab might still be stuck in March at 50° F. Warm air sits on this cold slab, dropping moisture as it cools.