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PU Combi Injection Resins

PU combi injection resin for a permanent sealing effect with fast foam formation

PU combi injection resin is a PU hybrid product consisting of polyurethane foam resins (PU foam) and polyurethane resins (PU). This injection material stands out due to its fast foam formation upon contact with water and its permanent sealing effect. But it also reacts without water contact forming a compound of constant volume. PU combi injection resin combines the positive properties of PU foam resins and PU resins. It is suitable for specific application ranges such as crack injections and damp proof courses in case of large cavities and in-situ water (short working time). PU hybrid resin from WEBAC is compatible with concrete, steel, masonry mortar, foil and cable sheathing.

Application ranges of PU combi injection resin

  • Crack repair in concrete and masonry according to DIN EN 1504-5
    (CE Declaration of Performance/2+)
  • Seepage in concrete
  • Sealing of water-bearing construction joints (gravel nests/honey combs)
  • Filing of cavities in masonry and concrete in case of water inrush
  • Damp proof course (dpc) in masonry, particularly for higher humidity classes
  • Foundation pit sealing


Preparatory work

Structural analysis before using PU combi injection resin: 

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

This provides information on: 

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

Loose plaster layers in the area of the injection level must be removed. Porous joints and defective masonry areas must be patched with quick-setting cement. Gravel nests and cavities to be filled must be free of dirt, oils, grease and other separative components.

Application of PU combi injection resin

The material is injected at an injection pressure adapted to the nature and condition of the building structure. The injection process must be continued until resin starts to emerge from the masonry into the area of the adjacent packers. An even material distribution has then been obtained. The material temperature and that of the structural element influence the reaction speed of PU combi injection resin. Higher temperatures accelerate the reaction, lower temperatures have the opposite effect. Only inject pure WEBAC PU combi injection resin – without residues from cleaning agents or other foreign substances.

Application by 1C pump: 

  • Transfer the mixed material to the pump’s hopper
  • Stir briefly 
  • Provide for an even material flow
  • Short working time

Final work 

  • Remove the packers after completing the injection process and when the WEBAC PU combi injection resin has cured
  • Close the drill holes with suitable mineral building materials


  • Clean tools and equipment with WEBAC® Cleaner A when interrupting work for a longer period of time and after use 
  • Use WEBAC® Cleaner B for etching all cured material but never use it for rinsing pumps
  • Fill the entire pump system with WEBAC® Lubricant or hydraulic fluid in case of long standstill periods