Waterproofing and damp-proofing materials

WATERPROOFING AND DAMP-PROOFING MATERIALS

Waterproofing is a surface treatment of a structure to prevent passage of water from one side to another under normal or hydrostatic pressure. Damp-proofing is the treatment to prevent passage of water from one side to another by capillary action. Both waterproofing and damp-proofing are done using the same materials for RCC roofs, basement walls and flooring. The various materials used for this purpose are briefly explained below.

1. BITUMINOUS MATERIALS

Earlier bitumen was impregnated with vegetable or animal fibres and sheets were made. The popular trade name was tarfelt. Such sheets were fixed to concrete roofs with the help of hot bitumen. The drawback of such sheets was that blisters were formed due to vaporization of moisture underneath. As a result, leakages were seen for a long time soon after the rainy season. Hence, these sheets are replaced by sheets of fibreglass and plastics.

2. INTEGRAL COMPOUNDS

In cement mortar or concrete, 2% of water proofing compounds like Pudlo or Impermo may be added. These compounds are available in the form of powders. They improve workability with minimum water requirements. Ultimately, it reduces permeability.

3. EPOXY-BASED MATERIALS

Epoxy materials are used for waterproofing terraces, basements and bathrooms. Two coats of epoxy mix results in a reasonably good waterproofed surface.

4.  ELASTOMERIC MATERIAL

Elastomeric material is a special paint for waterproofing. Using rollers, spray or brush, it is applied to concrete surfaces in two coats. The thickness of each coat may be 0.5-0.75 mm. Among many varieties, acrylic paints are the most popular.

5. SLURRY COAT

These are cement -based chemicals in which silica sand acts as a carrier. During hydration, they form crystals which fill the pores in cement. The crystals prevent the passage of water but permit vapours to escape. The slurry coat may be applied with brushes or by grouting.