What is that white powder?

The powder is called efflorescence

Concrete is naturally porous (12%-18% air) - when it cures, surplus water escapes and creates a network of interconnected capillaries, much smaller than human hair (10-100 nm). The capillaries draw water from the ground by wicking action or let in water under hydrostatic pressure. The pores also let in water vapor and radon gas, which are pulled in by the lower air pressure and concentration indoors.

The white power seen on some concrete floors is created by water pushing up through concrete, collecting and liquefying minerals as it goes.  Once the water reaches the surface and breaks through, it evaporates leaving the white power/efflorescence.   As seen by the picture on the right where the water vapor has lifted the epoxy off and broken through the coated floor, evaporated leaving the tell-tail white power.

There is a cure for the problem that allows the concrete floor to be coated without the fear of seeing your once beautiful epoxy coated floor destroyed by an unseen vapor. 

This cure is a new technology sealer component that penetrates 24 inches into the microscopic pores and hardens.  Similar to filling the pores with a hard plastic like epoxy.  Water or efflorescence cannot budge it and it becomes permanent protecting the epoxy coating that beautifies your floor.

This new technology is called 8000 CMW Moisture Vapor Barrier.  Unique characterizes CMW incorporates a reactive silicate and non-silicate based multifunctional crystal growth matrix that reacts with hydroxides and tri-calcium silicate and various ion components within the capillary/pore matrix structure of the concrete.  This reaction creates a calcium-silicate hydrophilic particle grain crystal/hydrogel with a non-diluting property that will repel absorption of penetrating liquids and substantially hinder and eliminate the passage of liquids and vapors through concrete structure.

What all this technical jargon means is:  IT WORKS! 

The bottom line is, if mother nature wants to force something up through the ground and through concrete, she will and nothing man-made can stop her.  CMW is an amazing product and will stop most vapors that are pressured through the ground.