Material Properties

The non shrink cement slurry shall be used for filling cracks of width greater than 8 mm in concrete and masonry, sealing honeycombing / voids in concrete, using injection grouting method. The slurry shall be made at site by the addition of plasticising and expanding grout additive to a cement slurry mix.

Surface Preparation

Clean the concrete surface along the crack. Surface cracks should be sealed to keep the grout from leaking out before it has set. A high strength, rapid setting and water insensitive polyester resin based mortar shall be used for this. The material shall be applied by cutting a V groove along the crack line.

Installation of grouting nozzles

This method shall be used in conjunction with V grooving of the cracks. The method entails drilling a hole into the crack, approximately ¾” in diameter and 1/2 to 1” below the apex of the V-grooved section. In this holes fix PVC or Aluminium Nozzle and seal with a high strength, fast setting plugging compound. If polyester resin mortar is used for filling grooves, the same materials shall be used for plugging the entry port. When the crack is sealed, flush with water to clean it and test the seal for any leakage

Preparing grout mix

Injection grout mix shall have the following mix proportions.
Cement : 50 Kg
Pidicrete AM : 225 gms
Water : 20-22 litres
The grout mixture should be mechanically mixed using a forced action mixture to a uniform consistency

For small volumes, a manual injection gun may be used; for larger volumes, a pump should be used. The pressure used for injection must be carefully selected based on grout properties, crack characteristics, and structural integrity of the medium to be grouted
A pressure of 2-3 kg shall be maintained during grouting.

If the crack is vertical, the injection process should begin with pumping grout into the entry port at the lowest elevation until the grout level reaches the entry port above. The lower injection port is then capped, and the process is repeated at successively higher ports until all the nozzles are grouted and capped.

For horizontal cracks, injection should proceed from one end of the crack to the other in the same manner.

If the pressure cannot be maintained, the grout will flow into the unfilled portions or will leak out of the crack.

After the grout has set completely, the extra length of the nozzle shall be cut or removed from the surface.

Filling Honeycombing / Voids in concrete

The same grout mixture shall be used for this purpose. The injection ports should be fixed on the entire area to be grouted in a staggered manner at distance of 500 mm c/c. Fixing or as directed by the concerned engineer, sealing and grouting of injection ports shall be carried out as per the application methodology given above.