Repair of Cracks

• Remove the plaster near the cracks from inside as well as outside of the brick walls and clean the cracks thoroughly with water and air jets. Remove some extra masonry in the form of holes along the cracks at suitable intervals for acting as places to receive grout. (See Figure 1)

• Wet the cracks by sprinkling water

• Fill the cracks in the whole thickness of the wall with neat cement grout in fine cracks and 1:6 cement-sand mortar in wide cracks. The filling of cracks should be done starting from bottom towards top of the wall through the ports or holes made in step 1.

• Final plaster or finish to be carried out after undertaking all the strengthening measures

 

How do I strengthen my walls?

• If the length of the wall is more than 16 times the thickness of the wall and/or the height of the wall is more than 14 times the thickness of the wall, provide external or internal buttresses. The spacing of the buttresses shall not be more than 14 times the thickness of the wall. (See figure 3).

• Provide ferro-cement jhali for reinforcement of areas all around the openings in the walls like doors, windows and ventilators. (See Figure 4)

• Provide seismic belts on all walls on both sides above lintel level and just below slab level. Seismic belt shall be made as follows: (See Figure 5 & 6)

  Height of belt = 400 to 450mm;

  longitudinal wires in weld-mesh= 16 Nos of about 2mm dia at 25mmc/c

  transverse wires same diameter at about 150mmc/c;

  micro-concrete 1:1.5:3 or cement-coarse sand mortar 1:3 of 30-35mm thickness

  The plaster from existing wall shall be completely scrapped and removed,

  The joints in the walls shall be raked to 12-15mm depth.

  Clean the surface, wet surface with water and apply neat cement slurry

  Plaster first coat of 12 mm thickness and roughen its surface.

  Fix the wire mesh prepared above with 150mm long nails at about 450mm centre to centre distance while plaster is still green.

  Apply second coat of plaster 16mm thick.

  The wires mesh should be continuous with 150mm overlap at corners or joints if required.

 

How do I strengthen my roof?

• Make the seismic belts on the wall sides just below floor and roof as mentioned above under 3.1.c.

• Tie the rafters of the roof with the seismic band provided as above.

• Connect the opposite rafters on both sides of the ridge near about mid-height of the roof through bamboo ties nailed to the rafters.

• Just below these ties, fix long bamboos across the rafters nailed to all the rafters in the room.

• Provide cross bracing near each end of the room using bamboos which should cover and connect to three or four rafters each. (See Figure 7)

 

How do I strengthen the corners of the buildings?

• The corners can be strengthened by installing ferro-cement plates at the corners. (See Figure 2)

• Use weld-mesh in a width of 450 to 500mm on each side of the corner at about 900mm above the floor.

• Second such band need not be provided when seismic bands have been provide as mentioned above.

• The ferro-cement band must be constructed in the same way as a seismic band.

 

How do I strengthen my foundations?

• Adding strong elements in the form of reinforced concrete strips attached to the existing foundation part of the building.

• These will also bind the various wall footings and may be provided on both sides of the wall.

• To avoid digging the floor inside the building, the extra width could be provided only on the outside of external walls. The extra width may be provided above the existing footing or at the level of the existing footing.

• The reinforced concrete strips and the walls have to be linked by a number of keys, inserted into the existing footing (See figure 8)

 

 

Figures

Figure 1

 

 

 

 

 

 

 

 

 

Figure 2

 

 

 

 

 

 

 

 

 

 

Figure 3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4

 

 

 

 

 

 

 

 

 

 

Figure 5

 

 

 

 

 

 

 

 

 

 

 

Figure 6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 8