Strengthening and Modifying Masonry Walls: A Comprehensive Guide

Posted on May 2, 2024 in Technology

Strengthening Reinforced Concrete Structures

Jacketing

Jacketing involves adding a reinforced concrete section to an existing structural member, restoring it to its original dimensions or increasing its size using suitable materials.

Sprayed Concrete (Shotcrete)

Sprayed concrete is a common technique for repairing and strengthening reinforced concrete structures. Two processes are used: dry mix and wet mix sprayed concrete.

Fiber-Reinforced Polymer (FRP)

FRP is a strong, lightweight, corrosion-resistant building material made of a combination of materials for enhanced performance.

Forming New Openings in Masonry Walls

Preparation Works

  1. Check for utilities in the area.
  2. Measure and mark the new opening’s position.
  3. Mark the lintel position, ensuring proper spacing.
  4. Protect flooring with OSB boards and geotextile fabric.
  5. Set up metal props for support.
  6. Position the lintel and props.
  7. Create holes in the wall for the lintel.
  8. Start holes above the lintel position.
  9. Make holes larger than the needle size.
  10. Thread needles through holes and secure to props.
  11. Fill the gap with dry pack material.
  12. Use a screw jack for additional support.
  13. Wear safety gear: goggles, helmet, gloves, and steel-toe boots.

Opening Excavation

  1. Remove plaster from the designated area.
  2. Chip away bricks to create a 12-inch gap.
  3. Cut a hole for the lintel with 50mm extra space on each side.
  4. Install the first two lintels, ensuring they are level, and fill with dry pack.
  5. Double-check alignment and allow 24-hour curing.
  6. Install metal beams on one side after lintel installation on the other side.
  7. Remove plaster from the corresponding wall section.
  8. Chip away bricks to create a 12-inch gap.
  9. Cut another hole for the lintel with extra space on each side.
  10. Install the next two lintels and fill with dry pack.
  11. Verify alignment and allow 24-hour curing.
  12. Fill voids around the lintel with cement mortar or brick pieces.

Door Opening Excavation

  1. Once hardened, remove the lintel, props, and needles.
  2. Carefully remove bricks while supporting the remaining structure.
  3. Fill holes with cement mortar after brick removal.
  4. Fill needle holes with cement mortar and replace bricks.
  5. Apply new plaster after filling holes and voids.

Finish Work

  1. Finish plastering, frame installation, and other tasks.
  2. Remove OSB boards from the work area.
  3. Apply a new coat of paint to the structure.
  4. Install skirting or baseboards if necessary.
  5. Thoroughly clean the workplace after all tasks are complete.

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Removing Load-Bearing Walls

Work on the Upper Floor

Use temporary timber propping with offset timber posts. New lintels made of rolled steel joists (RSJ) are located at the floor structure level, providing definitive support. Joists are extended on both sides by additional short timber beams. Temporary propping is made of RSJ.

Not Working on the Upper Floor

When removing a load-bearing wall, the new steel beam needs support. New lintels made of RSJ are located under the floor structure, providing definitive support. Temporary propping is made of timber.

Non-Load-Bearing Walls

Work on the Upper Floor

  • Use temporary timber propping to support the partition.
  • Use temporary propping made of RSJ to support the partition.
  • The partition is supported only by finally fitted RSJ lintels located on the upper floor.

Technological Process of Removing Masonry Partitions

  • The partition is supported only by finally fitted RSJ lintels located on the upper floor.
  • The partition is supported only by finally fitted RSJ lintels located in the floor structure.

Not Working on the Upper Floor

  • Use temporary timber propping to support the partition.
  • Use temporary propping made of RSJ to support the partition.
  • The partition is supported only by finally fitted RSJ lintels.

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Temporary Supporting Structures

For larger openings, use steel beams like rolled steel joists (RSJ).

Method 1: Installing Lintels from One Side, Then the Other

  1. Cut the hole.
  2. After placing the new lintel, wedge between the top of the lintel and the brickwork above. Use the same procedure below the lintel when installing the first lintels.

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Method 2: Installing Lintels from One Side, Then the Other, and Finally the Inner Beam

Install the lintels first from one side, then the other, and finally insert the inner (central) beam.

Types of Temporary Supporting Structures

Propping provides provisional vertical support. Types include Acrow props, proprietary horizontal steel frames, strongboys, and steel plates.