3 Materials for maintenance and repairs

 

3.1 Types of Repair Materials & Material Selection

Types of Repair Materials:

1. Cement-based: Mortars, grouts, non-shrink cement.

2. Polymer-based: Epoxy, acrylics, polyurethanes.

3. Steel/Metal: Clamps, rods, wire meshes.

4. Composites: Ferrocement, fiber-reinforced concrete.

5. Sealants: For crack filling and joints.

6. Waterproofing compounds: Slurries, membranes.

Material Selection Criteria:

• Compatibility with base material (concrete, brick, etc.)

• Mechanical strength

• Chemical resistance

• Workability

• Durability in environmental conditions

• Ease of application

Example: Epoxy is ideal for RCC crack repair due to high bonding and compressive strength.

---

3.2 Essential Parameters for Maintenance and Repair Materials

1. Bond with Substrate:

   • Critical for ensuring the repair material integrates and doesn't separate over time.

   • Example: Epoxy resins form strong adhesive bonds with concrete.

2. Durability:

   • Resistance to weathering, chemicals, and mechanical stress.

   • Long life of repair = cost-efficiency.

3. Shrinkage:

   • Low shrinkage prevents new cracks.

   • Non-shrink mortars are often used in structural repairs.

4. Workability & Setting Time:

   • Should allow easy application and proper finishing.

   • Quick setting materials are useful in emergency repairs.

---

3.3 Waterproofing Materials

Waterproofing materials prevent ingress of water, protecting the structure from dampness, corrosion, and deterioration.

---

3.3.1 Polymer Modified Cement Slurry (PMCS)

• Composition: Cement, water, and polymer additives (SBR or acrylic).

• Application: Applied as a slurry coat over RCC, bathrooms, terraces.

• Advantages: Flexible, strong adhesion, economical.

---

3.3.2 UV Resistant Acrylic Polymer

• Composition: Acrylic-based liquid waterproofing membranes.

• Use: Exposed surfaces like terraces and balconies.

• Benefits: UV stable, elastic, weather-resistant.

• Example: Coating over roofs for monsoon protection.

---

3.3.3 Ferrocement

• Composition: Cement-sand mortar reinforced with wire mesh.

• Use: Water tanks, repair of slabs, sunshades.

• Properties: Crack-resistant, high tensile strength, waterproof.

• Example: Replacing cracked chajja using ferrocement slab.

---

3.4 Repairing Materials for Masonry

---

3.4.1 Plastic/Aluminum Nipples

• Used to inject grout or chemicals into masonry cracks.

• Placed inside drilled holes to distribute materials.

• Useful in damp-proofing or retrofitting.

---

3.4.2 Non-Shrink Cement

• Special cement that doesn't shrink during setting.

• Prevents gap formation and restores structural integrity.

• Used in void filling, anchor fixing.

---

3.4.3 Polyester Putty / 1:3 Cement-Sand Mortar

• Polyester putty: For minor surface defects, cracks.

• 1:3 mortar: Traditional repair material for masonry.

• Use depends on the type and depth of damage.

---

3.4.4 Galvanized Steel Wire Fabrics & Clamping Rods

• Provide external confinement and reinforcement.

• Used to tie and hold cracked masonry walls together.

• Example: Strengthening earthquake-damaged walls.

---

3.4.5 Wire Nails

• Used for fixing steel meshes or ferrocement panels.

• Ensure firm anchorage of repair elements.

---

3.4.6 Ferrocement Plates

• Prefabricated thin ferrocement panels.

• Used for overlaying damaged walls or chajjas.

• Lightweight and strong.

---

3.5 Repairing Materials for RCC (Reinforced Cement Concrete)

---

3.5.1 Epoxy Resins

• Two-component adhesive.

• High strength, chemical resistance, excellent bond.

• Used in crack injection, bonding old and new concrete.

---

3.5.2 Epoxy Mortar

• Epoxy mixed with sand or fine aggregates.

• High compressive strength, ideal for structural repairs.

• Used for patching damaged RCC sections.

---

3.5.3 Cement Mortar with Polypropylene & Silicon

• Improves flexibility, adhesion, and waterproofing.

• Suitable for repairing RCC surfaces exposed to moisture.

---

3.5.4 Polymer Concrete Composites

• Concrete modified with polymers (latex, epoxy, etc.).

• Increased toughness and water resistance.

• Suitable for bridge decks, industrial floors.

---

3.5.5 Sealants

• Flexible materials used for sealing joints and cracks.

• Types: Polyurethane, silicone.

• Allow for thermal expansion and prevent water entry.

---

3.5.6 Fiber Reinforced Concrete (FRC)

• Concrete with added steel, glass, or polypropylene fibers.

• Increases tensile strength, ductility, and crack control.

• Ideal for seismic retrofitting and overlays.

---

3.5.7 Emulsions and Paints

• Acrylic, bituminous, or elastomeric paints.

• Provide waterproofing and protection.

• Applied on external walls, roofs, or repaired areas.