SPACES Sept issue 2017

BASU BABU TIWARI, CONSULTING ENGINEER
After doing multiple visits to the project site to assess seismic damage a retrofit plan
was developed. Some key components of the plan were:
• Corner Strengthening with Helifix: From the exterior, 16 mm reinforced bars were
inserted in a 20 mm diameter hole, diagonally created with rotary drill, at 2’ c/ c
spacing. With the bar in place, the hole filled with polymer non-shrink mortar and
both ends plugged with high strength mortar.
• Junction Strengthening: From the interior, a 12 mm diameter bar was inserted at
every 2’ spacing in a L-Shape. To accommodate the bar one course of brick was
removed each side of the wall, bars inserted and gap filled with micro concrete.
• Bands: At three levels - Lintel, around Jambs and at the Sill - bands were run
around the entire perimeter. A 250 mm width MS mesh fabric of 2 mm diameter
and having a mesh size of 25 mm from both faces of wall around opening was run
around sill and lintel level wherever possible. A 40 mm thick application of micro
concrete across the mesh was cured for 7 days.
• Soil Cement Grouts: For existing walls and cracks, a soil cement grout was injected
at low pressure (.1 to .025 MPa). After using an initial injection of water to clean the
insides and improve cohesion, the grouting mix (cement water 1:1) was added. •
SEPTEMBER 2017 SPACES / 35