stitching of wall corners and use of tie rods

STITCHING OF WALL CORNERS

Presented by,Nayana DParvathy G VijayanVrinda JAnandalekshmi B

CRACKS AT CORNERS Vertical cracks are common at corners of masonry

buildings. REASONS These fractures may occur due to thermal/ moisture

movement.

Perpendicular walls may expand towards each other in the direction of the corner, causing rotation of the brickwork and eventual cracking in the masonry at the near the corner.

differential movements in a wall, for example where a bulging flank wall meets a straight and stable corner.

How to repair cracks in walls?

Shaped and twisted stainless steel rods are bonded into the walls, stitching the masonry across the cracks at regular intervals. The brick stitching system allows the cracked wall to behave as a reinforced non-fractured unit.

REINFORCING EXTERNALCORNERS WITH CRACK STITCHING BARS

Reinforcing external corners with crack stitching bars.

A series of helical bars are used

Bars are bent at a right angle, are bonded into slots with polymer modified grout

The bars form layers of concealed reinforcement for stitching cracks at a corner

STITCHING CRACKS AT A CORNER OF A BUILDING WITH LONG DRIVE PINS A series of long drive-in helical wall ties are driven from the corner of a building into the both flanking walls to form a succession of perpendicular tie straps.

The 12mm diameter ties corkscrew into small 8mm pilot holes when driven with the impact action from an SDS hammer-drill.

The tie grips the brickwork along the entire length of the helix to provide a tension strap that reconnects and strengthens masonry adjacent to the cracked corner.

How are wall stitching bars installed?

A horizontal channel is cut in the masonry, usually in the bed joint where installation can be easiest disguised.

The slots are flushed with clean water immediately

prior to the installation of a high performance cementitious grout.

Brick stitching bars are simply pushed into the grout, ensuring full insertion of the bars along their length.

The helical bars extend 500mm each side of the cracks to dissipate loads and disperse them evenly into the wall structure.

Chase slots along the length of wall that extends 500mm each side of crack.

Flush the slots thoroughly with clean water to remove loose material and to reduce the tendency of porous brickwork to suck moisture from the grout.

Working from the back of the slot fill to two thirds full with grout, leaving room to repoint and match existing finishes.

Push the crack stitching bars into the slot ensuring they are fully encapsulated in the grout.  The bars must extend 500mm each side of the crack to allow them to absorb loads and to disperse them evenly into the wall structure.

Make good disguise to slot.It is important to ensure all cracks in walls are filled and sealed.   

Use of tie rods

Metal ties are widely used in traditional buildings

Used in wall –to- wall connections and wall- to –floor connections

Utilising tie rods to absorb horizontal impulses in arches

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Tying of masonry vaults with tie rods

Using tie rods in roofs

ADVANTAGES•LOW COST

•EASY INSTALLATION

•EASY MAINTENANCE

•DECREASE THE PROBABILITY OF OUT OF PLANE FAILURE