What is evaporation and why is it important for it to occur? Evaporation is when a liquid is turned into a gas. This natural process is important because it allows for the water on top of the concrete to turn into gas and allows for additional water still in the concrete to move to the surface. This cycle keeps happening until there is no longer a source of water or a permeability is emplaced to cut off the surface from the source of water. If all of the water is not evaporated, the adhesive will not bond correctly to the concrete. Overall, evaporation is a crucial process in the bonding process.