Importance of Waterproofing Structures

The longevity of structures depends on how much resistance the building element will offer to water ingress. Water leakage not only reduces the durability but also hampers the serviceability or usability of the structure; hence, a good waterproofing system will address the issues of long-term and usability aspects.

M N Ramesh, Managing Director, Talrak Construction Chemicals

Waterproofing is a key activity of the building process. However, sometimes waterproofing problems require individual solutions. That is why a skilled technical team should work together with designers to analyse each situation in order to develop a customised solution which meets the individual requirements of a given project. In other words, waterproofing should commence from the drawing board stage.

Why is waterproofing so important? Each year, around the world, massive amounts of money are invested into infrastructure, public, and private building projects. According to a report on distress in building structures, 80% of damages ultimately relate to waterproofing issues.

Investing in high quality waterproofing not only protects construction elements against water ingress but also ensures resource efficiency, low maintenance costs, and high return on investment in the long run.

New Construction Projects
In new constructions, external basement waterproofing and waterproofing under the foundation plate protect against water ingress from surrounding soil. TPO roofing membranes protect flat roofs that can last for 50 years in any climatic region around the world. Liquid applied polymer coatings protect balconies and terraces against weathering. Cementitious materials with drinking water certification safeguard drinking water on the inside of potable water storages.

In commercial building projects, decorative flooring combines design with easy cleaning. In industrial facilities, highly resistant floor coatings protect concrete floors from traffic or contamination by oils, acids as well as provide slip resistance. Joint sealants and injection gels help to successfully build underground infrastructures such as new metro lines and tunnels. Water repellents protect buildings and infrastructure from water ingress while special coatings protect façades in coastal areas against the aggressive and salty air.

Remedial Waterproofing Systems
In restoration projects, cementitious crystallizing waterproofing materials provide waterproofing from the negative side such as in basements or tunnels. Special fast setting blitz mortars can even stop flowing water. Curtain injection or area injection are special solutions that are able to waterproof the external side of a construction without direct access. Horizontal barriers stop rising damp (capillary action) in walls while restoration plasters support the drying process by preventing salts from damaging the building substance. Moisture control systems protect against vapor migration through the concrete slab and prevent flooring failure.

Infrastructure forms the heart of trade and commerce in a modern world. Its reinforced concrete structures need to be maintained for secure transportation today and tomorrow. Crack injection technology is capable of repairing cracked concrete structures, whether against active water pressure or just for restoring structural strength.

Key Parameters of a Negative Side Waterproofing System
For successful waterproofing of a structure from the negative side, the ideal product should have the following properties:

• The waterproofing product should be mineral based, just like the brick or concrete substrate and it has to become one with the substrate.
• It should ideally penetrate a little into the substrate; that way it cannot be pushed off by the water pressure.
• It has to be open to vapor diffusion so that water vapor can penetrate the cured coating.
• It should be free of chlorides so that it does not harm the steel reinforcement.
• It should resist high water pressure from the negative side.
• The product should be easy to apply.
• It should have self-healing properties to avoid leakages from minor cracks.

The mineral substrate has to be sound and solid as well as free of grease, oil and loose particles. Prior to application, the substrate has to be wetted and standing water has to be avoided. Dusty or salt-contaminated substrates are primed with a crystalline stabilizing penetrating primer.

Salt Laden Substrates
When sufficient crystallization has taken place, the pressure in the capillaries will get so high that the building material is destroyed. The material loses its mechanical strength and becomes brittle, resulting in a damaged surface.

A typical sign of salt contamination is salt efflorescence, mostly seen as a whitish substance on the surface of masonry or concrete. Often the salts are transported from the surrounding soil through the capillary system of the building materials by rising damp. After a while, paints or conventional plasters are simply pushed off by the pressure of salt crystallization.

For restoring salt contaminated substrates, products that can be used should be flow viscous and products based on a combination of polymers and silicates. When it is sprayed onto the surface of the substrate, it penetrates into the capillaries. It reduces the pore volume, lowering the danger of renewed salt efflorescence, and also increases the chemical and mechanical resistance of mineral building materials. The polymers ingredient encapsules the salt molecules and reduces their mobility, preventing the leaching out of efflorescence.