Introduction
Structures in the ground must be protected from the various forms of water in the ground and its harmful effects. Hazards include soil vapour, soil moisture or groundwater. Different forms of water require different levels of protection. Typically, we assign the same level of protection for both soil vapour and soil moisture. As a general rule, all parts of the building in contact with the ground are uniformly provided with minimum protection against soil moisture. Structures below the defined groundwater level should have a higher level of groundwater protection.
Waterproofing materials
Bituminous membranes, plastic membranes, waterproofing mortars, waterproofing concrete, and metal sheeting can be used to waterproof against soil moisture and groundwater.
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1. Bituminous Waterproofing
1. Bituminous Waterproofing
The number of layers of bituminous waterproofing depends on the functional use and the thickness of the membrane. Against soil moisture, 1-2 layers are required, while against groundwater, 2-3 layers are needed, depending on whether a 2-4 mm thick thin membrane, a minimum 4 mm thick heavy-duty membrane, or modified forms of these are used. Using modified thick membranes will require the least number of layers.
Corners are extremely stressed areas and therefore they need special care by forming 4-5 centimetre-radius bends here. Before laying the membrane, ensure that the surfaces are smooth, dust-free, and primed with a bituminous coating or emulsion.
Bituminous membranes are available in rolls of 10 or 20 metres with a width of 1 metre. The membranes must be folded perpendicular to the wall, cut to size, and rolled back. They can then be bonded by flame welding the entire surface, using a blow torch to melt the bitumen from the base layer while slowly re-rolling the membrane.
The sheets must be laid with a minimum end overlap of 10 centimetres and 15 centimetres laterally, and the overlap has to be carefully rolled. It is sufficient to weld the modified sheets along the overlaps, or point by point on a horizontal surface. In the case of self-adhesive sheets, full-surface bonding is done by continuously removing the protective film.
The sheets must be laid with a half offset for multi-layer waterproofing.
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2-5. Plastic And Other Types Of Waterproofing
2. Plastic Waterproofing
In all cases, plastic waterproofing is applied as one layer, with a minimum thickness of 1 millimetre. Remove protruding particles and dirt from the surface and dust the surface. Instead of priming, use a plastic felt for levelling. At the corners, a 1.5-centimetre-radius bend has to be created. The plastic sheets are laid dry without bonding, while on the vertical surface, there is need for a hanging fixing. The overlap between the plates should be at least 5 centimetres. Joints are made either by hot air welding or by solvent welding.
3. Waterproof Coatings
Waterproof coating is commonly used for floors and plinths as an additional protection against soil moisture, which can be made continuous with sheet waterproofing. The required overlap is 15 centimetres. Materials can be bituminous, plastic, cementitious or resin-based. The coating is applied in 2-3 layers using a trowel. The temperature required for construction must be at least 5 degrees Celsius. In the first layer, reinforcement strips should be embedded in the coating at corners, curves and planes of different levels. The follow-on coating layer can only be applied after the previous layer completely dries.
4. Sheet Metal Waterproofing
Sheet metal waterproofing can be used under monolithic reinforced concrete pillars between the base of the pillar and the reinforced concrete foundation. The waterproofing sheet of the floor is fixed to the metal sheet with clamp profiles.
5. Watertight Concrete
Watertight concrete is another way to protect against water. In this case we even have to be careful about the connection between the individually made structural elements and the proper sealing of the joints. Use a swellable water bar (placed in fresh concrete) in the centre line between the reinforced concrete basement wall and the slab foundation. Furthermore, a flexible joint tape can also be used in the former situation, as well as, for example, for the watertight sealing of construction joints.
