Important Things to Know About Concrete Waterproofing

Shashank Nakate Nov 28, 2018
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Concrete waterproofing is a process of making concrete surfaces, such as slabs, walls, floors, etc, water-resistant. The various methods and materials used in this process are described here.
Concrete by itself is not waterproof in nature, it is porous. Water seepage may cause damage to the construction leading to money losses, besides other inconveniences. Thus, waterproofing the concrete is a must for any building.

What is Concrete?

It is a construction material composed of cement, water, aggregates, reinforcing materials, chemical and mineral admixtures. The aggregates include sand and gravel. The reinforcing material is mostly the metal bars. Glass and plastic fibers can also be used.
Chemical admixtures add special characteristics to the plain concrete. Mineral admixtures are added to improve its strength. These can also be used as a replacement to the Portland cement present in the mix. Let us find more about the water proofing systems and related concepts.

Waterproofing Systems

The two important systems in these are Integral Waterproofing System and the other that uses membranes. Hydrophilic systems and hydrophobic systems are the subtypes. Among different hydrophilic systems, crystalline technology is the most popular one.
The water present is converted into insoluble crystals. Some hydrophilic products make use of a property called hydraulic swelling. The waterproofing material swells as it absorbs water, eventually filling the pore spaces present. In the hydrophobic system, externally applied products, viz. coatings, membranes, etc., are used as a protection against water.


Membranes are either liquid or sheet membranes. The liquid versions are sprayed on the concrete, forming a rubber-like coating about 60 mm thick on the surface. Quick application and low pricing are its major advantages. The sheet membranes are prepared from asphalt.
These membranes are laminated to polythene films and the sheets thus formed are then glued onto the surface. The sheets are consistent in thickness. Excellent waterproofing can be provided to the foundation walls, parking lots, tunnels, etc, using these sheet membranes. As this is done manually, it raises the labor cost which proves to be its disadvantage.

Hydrophobic Concrete

Unlike the hydrophobic membranes, 'hydrophobic concrete' is a totally different and innovative concept. Instead of applying any external agent for concrete waterproofing, here the mixture itself is manufactured water resistant. It is made hydrophobic by adding admixtures to it at the time of production.
These admixtures stop the capillary action occurring in the concrete. This has been successfully used in Asia, Europe, and Australia. It has also proved to be a boon for construction teams, since it allows construction to carry on even in the rains.

Crystalline Waterproofing

First of all, the concrete is saturated with water and then a low density solution is applied, followed by the crystalline material, which is a high density solution. After this, the chemical diffusion process starts. The high density crystalline solution seeps inside the concrete and travels towards the low density solution until an equilibrium is attained.
Since water is applied, cement hydration occurs. This hydrated cement now reacts with the crystalline material to form crystals. The diffusion process may take this crystalline waterproofing 12 inches inside the wall. This is highly efficient, because the crystals that are formed remain protected from any kind of external damage.
Resistance to 130 degree heat in a constant state is another advantage. It also resists chemical reactions like carbonation - which reduces alkalinity and damages the concrete. It stops chloride ion diffusion in the wall, protecting the steel present from oxidation and also expansion.

Before You Start

Before one starts the process, it is necessary to take into consideration some important points.
  • The surface should be clean. Any kind of debris, honeycombs, etc, should be removed.
  • Rough surfaces should be smoothened, and holes need to be patched up.
  • Check if the waterproofing material is compatible with the substance used for patchwork, so as to avoid any harmful chemical reactions.
  • Some of the products used are flammable and due care should be taken while handling them.
Following these cautions will help in making waterproofing a safe activity, that will strengthen your house in the best way possible.