Waterproofing and Damp Proofing

Concrete Waterproofing

  • Application of impervious material on concrete to prevent water penetration.
  • Concrete is pervious and absorbs water, contaminants, and chemicals.

Types of Waterproofing

  • Cementitious Waterproofing
    • Easiest method, materials readily available.
    • Used in wet areas like toilets and bathrooms.
  • Liquid Waterproofing Membrane
    • Thin coating (primer + 2 liquid coats).
    • More flexible, forms a rubbery coating.
    • Durability depends on polymer type (polymer modified asphalt, polyurethane).
    • Used for balconies, podium decks, green roofs, and water tanks.
  • Bituminous Coating
    • Flexible and protective asphalt coating.
    • Good for concrete foundations.
    • Not suitable for sunlight exposure (becomes brittle).
  • Bituminous Membrane
    • Popular for low sloped roofs.
    • Types: torch on and self-adhesive.
    • Self-adhesive: asphalt, polymers, and filler; low shelf life.
  • Admixtures
    • React chemically within concrete to make it a water barrier.
    • Types: Densifiers, water repellents, or crystalline admixtures.

Integral Water Proofing

  • Adding waterproofing material to cement or mixing water.
  • Uses chemical admixtures (dry powder or liquid).
  • Some forms self-heal minor cracking.
  • Crystalline Admixtures
    • Self-healing, seals cracks up to 0.5mm wide.
    • Useful for large concrete pours and cold joints.
    • Preferable for concrete subjected to hydrostatic pressure.

Steps in Waterproofing

  1. Surface Preparation: Clean surface thoroughly.
  2. Application of Primary Coat: Apply primer (solvent or water-based).
  3. Unrolling the Membrane Sheets: Align and adjust sheets.
  4. Heating the Membranes: Torch the underside to burn off film.
  5. Pressing the Membrane: Ensure proper bonding, especially at overlaps and edges.

Advantages of Waterproofing

  • Reduced water absorption.
  • Prevents crack formation.
  • Easy application.
  • Increased lifespan of concrete structure.
  • Prevents rusting of reinforcement.
  • Prevents dampness and seepages.
  • Reduces maintenance cost.
  • Increased property value.
  • Provides a healthy environment.

Disadvantages of Waterproofing

  • Bitumen softens under heat.
  • Bitumen has limited life due to solvent evaporation.
  • Polyurethane not very flexible.
  • Polyurethane hampers concrete's breathing capacity.
  • Polyurethane has limited pot life, water buildup under surface.
  • Cementitious: inability to hold up cracks.

Damp Proofing

  • Preventative measures to stop damp problems.
  • Damp walls can damage fixtures and cause structural damage.
  • Difference:
    • Damp proofing keeps out soil moisture.
    • Waterproofing keeps out both moisture and liquid water.
  • Damp proofing is a coating (usually asphalt-based).