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Tie rod hole sealing with Polyurethane Expanding Foam spray

Tie rod holes permanent sealing

Case Study : Exercise done & implemented at a reputed Construction company in Mumbai

What are Tie Rod Holes

During the construction  Polyurethane Expanding foam spraysmall metal rods, called tie rods, are inserted into the concrete form in order to hold the inner and outer forms together, and provide the structure with which the concrete can be poured. … After construction, they are usually either removed entirely, leaving a hole.

Tie Rod Hole packing is a commonly observed action during the time of finishing process of any construction. Most constructions will have tie rod enforcement holes equally spaced out on the walls. These can be observed  as small irregularities on the surface. Over time, these holes need to be sealed. This is to prevent any chances of future leakages or seepage through the wall.

Conventional methods for Tie Rod Hole sealing.

include ‘Swell Plugs’ , PU Injection grouting, cement grouting and etc. 

Problems with conventiional methods 
  • labour intensive – pu injection grouting/ cement grouting : high labour cost 
  • Time consuming 
  • Difficult to access from outside for high rise buildings- expensive scaffolding/ crane required.
  • Swell plugs are expensive and  also needs access from outisde.
  • effective waterproofing of tie rod holes is still uncertain.

Costing of Cement Grouting method

Considering the length of the hole to be 500 mm, with a diameter of up to 50 mm

  • 1 bag of 25 kgs (can fill up to 75 holes) = INR 275/-, material cost = Rs 3.67 per hole
  • Labor cost: 2 labourers will grout 50 holes per day. Let us assume they are paid INR 500/- each. Labour cost per hole= Rs. 20.

  • Cement grouting cost per tie rod hole= Rs 23.7
  •  This process is tedious, labor-intensive and for high rise towers inaccessible/unsafe for  manual grouting

Hole Sealing with Polyurethane Expanding Foam Spray

Expanding polyurethane Foam Spray Sealant Method – Using Supex 100 PUF Gun Grade Polyurethane Expanding foam spray
Application Procedure:
  • Clean the Tie rod holes with local water spray.
  • Apply Supex 100 PU foam using Gun.
  • Sealant will expand  and cure in 15 to 30 minutes.
  • Cut excess foam coming out of hole using knife.
  • Water  Test : spray water under pressure from one end to check  if it leaks to the other end.
  • Sanding, putty, plastering, painting can be done as we do with cement grouting

PU foam Spray costing:

Material Cost:
  • One 750 ml foam can, filled  (can fill  up to 66 holes of 20 mm diameter * 450 mm length), Approx Cost of one 750 ml can =300 + GST.
  • Per hole material cost = PU foam + Pu cleaner + Pu Gun = 4.5+.5+.5 = Rs 5.5
Labor Cost: One laborer can fill approx 250  holes in a day. Per hole labor cost = Rs. 2 (Rs. 500 per day labor cost)
  • Total cost =Rs. 7.5 per hole

Benefits of PU foam spray vs Cement Grouting

  • Cost saving of Rs 16.2 per hole, 68% reduction in cost.
  • Productivity improvement by 500%.
  • Leak free – better reliability
  • safe process
  • Improved aesthetics

Other applications of Polyurethane Expanding Foam spray

One-component spray polyurethane foam (PUF) is dispensed as a frothy liquid which expands and moisture-cures into a solid foam insulation and sealant. Fire Rated or regular PU foam are available in convenient aerosol cans .
  • Fixing of window/door Frame
  • Sealing Split AC holes carrying cables
  • Isolation/ Transition Joint seam between Wall and RCC Beam
  • Sealing of all Openings in Roof construction, expecially metal roof
  • Improving Thermal insulation in cooling systems
  • Filling free spaces, cracks, gaps, pipe peneratations
  • Sealing Duct Shafts
  • Model making, design patterns etc- film production, interior designers
  • sealing gap between cable and wires , gap between electric panel outlet-process plants
  • sealing gap between cable and wires- Solar industry
door gap filler

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