What Is Grouting?
Grouting is an advanced technique in which fluid-like material made up of cement, sand, water, or chemicals is injected into soil or rock formation to change its physical properties and the composite material is called grout.
The materials used for grouting depend upon different factors such as the type of soil or rock and the area to be grouted. In this article, different types of grouting are discussed.
Types Of Grouting
1. Permeation Grouting
It is a type of grouting in which grout is injected into the soil to fill the pores and joints without disturbing the soil’s structure and volume. Thus it permeates coarse and granular soils creating a cemented mass.
Various types of binders are used in this grouting technique, the choice mainly depends upon the permeability of soil. It is also known as cement grouting or pressure grouting.
When the coefficient of permeability is greater than 10^-2 cm/sec, water-cement mixes are used and for permeability as low as 10^-5 cm/sec, expensive resin-based grouts are used. Soils with K values lower than 10^-6 cm/sec are normally not groutable by permeation method.
Advantages Of Permeation Grouting:
- Possible in limited space or where access is difficult.
- Economical for underpinning applications over alternative methods like removal and replacement or piling.
- The footprint of excavations is maximum when compared to piled solutions.
- It can be adopted adjacent to existing foundations.
- Can be performed without disrupting normal facility operations.
- Create barriers to groundwater flow.
- Underpinning foundations.
- Provide excavation support.
- Stabilize and strengthen granular soils.
2. Compaction Grouting:
This type of grouting involves injecting a thick consistency of soil-cement grout under pressure into the soil mass, consolidating and thereby stabilizing surrounding soils.
The grout mix is designed in a way so that it does not permeate the soil voids or mix with the soil. Instead, it displaces the soil into which it is injected.
Advantages Of Compaction Grouting:
- i) Compaction grouting is suitable where access is difficult and space is limited.
- ii) Can be installed in a very short time.
- iii) Generates minimal site vibration.
- iv) No spoils are induced.
- v) No connections to an existing foundation structure.
- vi) Reduces existing foundation settling significantly.
- vii) Minimizes soil liquefaction potential due to earthquakes.
- viii) Provides accurate pressure and placement of aggregate grout structures.
- ix) Best remedy for sinkholes.
- x) Economical compared to some other soil stabilization and ground-shoring methods.
• It should not be used where the ground above the grouting area has limited overburden as it may heave the ground around the bulb column. Typically, an overburden of at least five feet is needed.
• It is not applicable to soils with low permeability such as clays.
- These types of grouting is suitable for loose granular soils, collapsible soils, liquefiable soils, soluble rocks, rubble fills, poorly placed fills, & reinforce fine-grained soil.
- It improves the bearing capacity of soil.
- It can repair, stabilize and prevent sinkhole potential.
- It decreases and corrects settlement.
- Can be used for the ground beneath settled structures in preparation for lifting and re-leveling them.
- Suitable for ground stabilization where pipes or conduits are or will be installed.
3. Jet Grouting
In this type of grouting, high-velocity fluid jet is used to physically disrupt the ground. The soil is eroded and grout is mixed with the soil during the process and thereby improving it. It is more costly than permeation grouting. There are three systems of jet grouting: Single, double, and triple jet systems.
Advantages Of Jet Grouting
- i) Effective across the widest range of soil types including silts and most clays.
- No material disposal and less working room is required.
- Ability to construct soilcrete around subsurface obstacles and limited spaces.
- Specific soil layers at depth can be improved without treating soils above.
- Can be used without disrupting normal facility operations.
Uses Of Jet Grouting
- Underpinning of structures, cut off walls for tunnels and open cuts, and consolidating sandy gravel, soft foundation, or clay soil.
- It can be used in any situation requiring control of groundwater or excavation of unstable soil.
- To Provide excavation support.
- To Seal the bottom of planned excavations.
4. Rock / Fissure Grouting
Rock grouting is fully or partly filling fissures, fractures, or joints in a rock mass by grout injection without creating new or opening existing fractures.
The grout is injected under pressure through a gap drilled into the rock mass for treatment. This type of grouting is normally done in fissured rock to reduce the flow of water along the joints.
- Reduces groundwater flows.
- Reduces rock deformation.
- Reduces transmissivity via interconnected porous zones in aquifers.
- Saves pumping costs during basement excavation.
- Helps to lower the groundwater levels outside of excavation.
- Underpinning application etc.
5. Compensation Grouting
In compensation or fracture grouting, cement slurry grout is injected into the soil with excessive pressure to form root-like or skinny lenses within the soil mass.
The root-like lenses compact the nearby soil and help to lift the overlying soil and structures. It considerably increases the density of soil mass and its macroscopic strength.
- Can be done from shafts/tunnels below the structure without accessing the affected building.
- Real-time monitoring of the grouting process and displacements of the soil and structures.
This type of grouting is used for different purposes such as
- Releveling structures.
- Bearing capacity/ settlement control.
- Mine stabilization/void filling.
Advantages Of Grouting
Different grouting types have different advantages which are already discussed above. Some of the advantages are
- It can be carried out in almost any ground condition.
- It doesn’t produce vibration and can be controlled to avoid structural damages
- Ground improvements can be measured.
- Can be used in inaccessible or limited spaces.
- Very useful for slab jacking to lift or level distorted foundations.
- Can be installed near existing walls.
Application Of Grouting
The application of different types of grouting are as follows:
- Stopping water flows in mines, tunnels, parkades, dams, and underground structures
- Soil stabilization.
- Underpinning structures, and mining applications.
- Bearing capacity improvements.
- Reducing and correcting settlement.
- Ground improvements.
- To Provide excavation support.
- Filling the void between the lining and the rock face in tunneling.
- Unusual and difficult geotechnical and structural problems.
In this article, I have discussed different types of grouting in construction, their advantages, and their uses. I hope you have now enough knowledge about it. You can share it and spread the knowledge.