Why Xypex for Power & Utility Structures

Read section

The Structures – The Problems

Xypex products play a key role in the waterproofing of concrete against water leakage, even against extreme hydrostatic pressure. The unique Xypex technology also protects concrete against the effects of sulfate attack and crack or joint failure.

Protecting Power & Utility Structures

The waterproofing and protection of concrete in power and utility structures has the following objectives:

To prevent the passage of water through the concrete due to hydrostatic pressure so as to protect the interior of the substructure from water-damage, and the reinforcing steel from corrosion. Depending on the local environment, concrete should also be protected from sulphate and chemical attack.

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 (faulty cold and construction 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.

Cracking

Cracks in the concrete are the most obvious means by which water and damaging chemicals can enter a structure. These cracks form in a number of different ways, but the most common are drying shrinkage, thermal cracking, strain formed cracks, settlement cracks and plastic shrinkage cracking in the slab.

Surface Deteroriation

The principal cause of surface deterioration in power plant structures is the impact of freeze-thaw damage. This damage can be long term, resulting in some form of surface rehabilitation during the service life of the structure.

Sulphate Attack & Alkali Aggregate Reaction

Where sulphates are present in water or soils, the permeability of concrete and the presence of water allows sulphate ions to diffuse into the concrete and create an expansive reaction causing spalling and deterioration. A similar effect is caused by Alkali Aggregate Reaction whereby the presence of water in concrete permits a reaction between silica in certain aggregates and the alkalis in cement.

Water Permeability & Corrosion

The primary purpose of waterproofing concrete power and utility structures is to prevent the intrusion of water into the structure and thus protect the reinforcing steel from the damaging effects of corrosion. The nature of concrete and the problems associated with placement and consolidation means having to deal with permeability issues permitting the penetration of water into the substrate and through to the reinforcing steel. With the presence of oxygen this can initiate corrosion.