The Structures – The Problems
Xypex products play a major role in the waterproofing and protection of concrete against hydrostatic pressure, cracks, joint-leaks, chemical attack and surface deterioration – problems typically encountered in the various concrete structures found in the water treatment process.
The waterproofing and protection of concrete in water treatment structures has two primary objectives:
To prevent water held in the structure from leaking out due to the hydrostatic pressure and to protect the reinforcing steel from corrosion.
The nature of concrete and its installation means having to deal with permeability problems created by the natural porosity of the concrete as well as defects (cold joints, honeycombs, rock pockets and tie-holes), joint leaks, freeze/thaw damage and drying shrinkage cracks. These problems typically leave the structure open to active leaks and accelerate the possibility of reinforcing steel corrosion and surface deterioration.
The addition of coagulants or flocculation chemicals such as iron salts, aluminum salts, or polymers creates an additional long-term problem for the concrete that can lead to surface deterioration. With a loss of concrete cover, the reinforcing steel in the structure becomes more susceptible to corrosion, deterioration, and ultimately results in the failure of the structure itself.
The backwashing process used regularly to clean water filtration tanks is a naturally abrasive process which attacks the surface of the tanks, removing the traditional waterproofing coatings used to protect them. This in turn exposes the concrete to hydrostatic pressure, resulting in reinforcing steel corrosion and leaking.