Injection grouting is a process of application of new material in cracks / voids / honeycombs in concrete surfaces. This process is adopted to repair damaged old concrete structural members and strengthen them.
Grouting can be done in various methods but injection method is adopted for accuracy and time saving. This technique is widely used for all types of structures, masonries, repair works to maintain strength and durability.
Why Injection Grouting?
Injection grouting is necessary for following purposes:-
- To repair damaged concrete surfaces
- To strengthen tunnel linings / structures
- To avoid seepage of water in stone masonries
- Dam construction – retaining walls
- Settlement of foundation
- Repair and retrofit unreinforced masonry
- For waterproofing
- Prevent spreading of hazardous contaminants
- Opening of underground structures
Methods of Injection Grouting
- Permeation / Penetration Grouting
- Done to strengthen existing concrete formation without changing volume and formation of structure
- Forms of penetration system
- Circular grout
- Direct grout
- Compaction grout
- Injecting grout via drill cases which are drilled in pre set depths
- Concrete grout injected under pressure
- Fracture Grouting
- Usually done in soil for increasing density for re-levelling structures
- Jet Grouting :-
- Done with jet under high pressure
- Soil and concrete are combined to get end product
Grouting Materials
- Cement based
- Pure cement mixes
- Admixed cement mixes
- Additive cement mixes
- Chemical based
- Epoxy (EP)
- Polyurethane (PU)
- Acrylics (AC)
- Silicate Gels (SG)
- Phenolic resin (PH)
Process of Injection Grouting
Chemical Grouting
- Cement , sand , water are mixed in proportion and paste is formed (C:S = 1:4)
- Cavities / holes are drilled around area to be grouted
- Paste is filled with help of injecting equipments into cavities
- If required , secondary holes are drilled between primary holes and filled with grout
Injection Grouting
- Removal of plaster / screed on the surfaces
- Holes are drilled in the damaged area at specified depth
- Grouting Packers made up of steel or aluminium are inserted in these cavities
- Pour chemical grout in the holes until it comes out from neighbouring holes
- Remove grout Packers after chemical sets
- Removal of excessive grout after drying
advantages of Injection Grouting
- Low material cost
- Easy to apply
- Fast setting time
- High penetration capacity
- Less number of labour required
- Suitable to all types of structures (RCC / NON RCC)
- Suitable for underwater works , soil permeability , water leakage
- Setting of foundation in old construction can be repaired without disturbing the structural component parts (substructure /superstructure)
- Durability , strength of structural material increases
- Density of soil increases
– Vrushali Pathak