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PU Injection Resins

Injection resin for restoring masonry: PU injection resins

Classic PU resins (WEBAC® 14xx) are characterized by their high elasticity and good adhesion. Cracks injected with PU material used for crack repair remain leak proof also in case of limited crack width modifications and if exposed to dynamic stress. 

PU resin is also suitable for the restoration of gypsum-based masonry or building constructions (sealing, stabilization and solidification). Thanks to the active principle of hydrophobizing capillary obstruction WEBAC PU injection resins have a durable sealing effect also in case of high water load classes. An even, closed and therefore watertight pore structure forms upon contact of the PU grout with or when mixed with water. 

PU resin for structural bonding of concrete and masonry

PU material of the new generation (WEBAC® 16xx) also allows for structural bonding in concrete and masonry structures thanks to its high flexural and compressive strength. WEBAC PU grouting is characterized by its compatibility with cable sheathing, foil, steel, concrete and masonry mortar. WEBAC PU resin is resistant to acids, salts and lyes damaging the building structure if their concentration is not higher than usual. 

Preparatory work 

Structural analysis before the injection: 

  • Structural condition
  • Hydrodynamic and hydrostatic conditions
  • Water loads
  • Salt contamination 

In case of pressing water it must be decided depending on the object if a preliminary injection of PU injection foam resin is required.

Please also note when repairing cracks: 

  • Crack characteristics (crack type, crack course, crack width, crack width modification, etc.)
  • Significance of cracks for the building structure

This provides information on: 

  • Cause of damage
  • Selection of suitable filling materials
  • Choice of drill-hole packers
  • Positioning of drill holes 

All loose plaster layers in the area of the injection level must be removed and all porous joints and defective masonry areas be patched with quick-setting cement. The cracks and voids to be filled must be free of dirt, oil, grease and other separative substances. The crack edges must also be cleaned. 

Application of PU resin

Polyurethane resin is injected at an injection pressure depending on the nature and condition of the building structure (<10 bar for low pressure methods, starting at approx. 20 bar for high pressure methods). The injection process is continued until resin emerges from the masonry into the area of the adjacent packers and an even material distribution has thus been obtained. The reaction speed is influenced by the temperature of the PU material and the structural element: lower temperatures slow down, higher temperatures accelerate the reaction. Only inject pure WEBAC PU injection resin free of residues from cleaning agents or other foreign matter.

Application by 1C pump: 

  • Transfer the mixed material to the pump’s hopper
  • Stir briefly

Application by 2C pump: 

  • Application with a 2C pump is possible at a mixing ratio of 1 : 1
  • Provide for a sufficient volume flow to ensure that components A and B of the 2C PU injection resin are mixed until homogenous in the mixing device (static mixer). 

 Injection resin: final work 

  • Upon conclusion of the injection and the curing process of the PU grouting, remove the packers
  • Close the drill holes with suitable mineral building materials