Concrete waterproofing is the application of impervious material layer on concrete which prevents water from penetrating and making the structure waterproof so that it remains relatively unaffected by water. Concrete is pervious and porous compound which absorbs water, waterborne contaminants and chemicals that will cause deterioration to concrete.
Types of Concrete Waterproofing
1. Cementitious Waterproofing
Cementitious waterproofing is the easiest method of waterproofing in construction work. The materials which are used for waterproofing of concrete are easily available in the market. This method is used in wet areas like toilets and bathrooms.
But since it is used in internal wet areas like toilets and bathrooms, it is not exposed to sunlight and weathering. Thus expansion and contraction process will not take place in cementitious waterproofing.
2. Liquid Waterproofing Membrane
Liquid membrane is a thin coating that usually consists of a primer coat and then two coats of liquid waterproof which are applied by spray or roller. It offers more flexibility than the cementitious type of waterproofing by forming a rubbery coating on the applied surface.
The durability of the waterproofing depends on the type of polymer used for the making of the liquid waterproofing. Liquid membrane composes of polymer modified asphalt. Polyurethane liquid membranes are also used for waterproofing.
3. Bituminous Coating
Bituminous coating is flexible and protective which is also called asphalt coating. It is a very good protective coating and waterproofing agent, especially on surfaces of concrete foundations. Bituminous coating is made of bitumen based material and it is not suitable for exposure to sunlight. It becomes very brittle and fragile due to long exposure to sunlight.
4. Bituminous Membrane
Bituminous membrane waterproofing is a popular method used for low sloped roofs. The bituminous membrane has a torch on the membrane and self-adhesive membrane.
Self-adhesive compounds comprise asphalt, polymers, and filler. The self-adhesive type has a low shelf life as bonding properties of the membrane reduces with time. It is a mixed substance made up of organic liquids that are highly sticky, viscous, and waterproof.
Torch-on membrane uses a fire touch to melt the bituminous layer on the member for bonding.
5. Admixtures
For the past years, a new type of waterproofing has been used around the world. These admixtures are added at the batching plant or on the site and it will react chemically within the concrete which turns the concrete itself into a water barrier. Integral concrete waterproofing systems can be Densifiers, water repellents or crystalline admixtures.
6. Crystalline Admixtures
Crystalline based systems typically come in a dry powder form. Crystalline systems actually use available water to grow crystals inside the concrete, effectively by closing the pathways for moisture that can damage concrete itself the water barrier.
Steps Involved in WaterProofing
Step 1: Surface Preparation
Clean the surface thoroughly free from loose materials, dust, and oil. Surface cleaning plays a very important role in all membrane based waterproofing coating systems.
Step 2: Application of Primary Coat
Apply a primary coat to prime the surface of the structure. Solvent-based or water-based primers are suitable for bitumen membranes.
Step 3: Unrolling the Membrane Sheets
Checking for the correct alignment and adjust the sheets wherever required and unrolls the sheets on the surface of the structure.
Step 4: Heating the Membranes
Heat with the torch the burn off film present at the underside face of the membrane. Now the membrane will ready for bonding with the underlying concrete surface.
Step 5: Pressing the Membrane
Press the membrane firmly ensuring proper bonding with the surface of the concrete. Additional care has to be taken for the overlaps, edges and angles to make sure proper bonding.
Advantages of WaterProofing
- Water absorption will be reduced.
- Prevents the formation of cracks on the surface of the concrete.
- Easy application.
- Increases the lifespan of the concrete structure.
- Prevents the rusting of reinforcement.
- Prevents dampness inside the building.
- Prevents seepages from the ceiling and walls.
- It reduces the maintenance coast of the building.
- The property value will be increased because no one wants to buy a house with water leaking problems.
- It provides a healthy environment, good waterproofing systems helps in creating a clean living and workspace. It safeguards the property as well as the people in it.
Disadvantages of WaterProofing
- Bitumen based products soften under summer heat due to black color.
- Bitumen based products have a limited life due to solvent evaporation.
- Polyurethane protective coating is not very flexible.
- Polyurethane protective coating hampers the natural breathing capacity of concrete.
- Polyurethane protective coating has limited pot life the impermeable surface coating allows water to build up below the surface coating.
- Cementitious waterproofing is the inability to hold up cracks, which further cause leakage.
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