Table of Contents
What Is Injection Grouting?
Injection Grouting is defined as the process of filling the cracks, and voids under pressure in the structural members for repairing the cracks and strengthening the damaged or deteriorated masonry structures.
In the process of grouting, the cracks and the voids are get filled with the help of grouting material which will get subsequently be hardened.
Injection grouting is a similar process to the injection of epoxy.
Grout is basically a flowable plastic material that has low shrinkage and is widely used for filling voids or gaps completely and will remain stable without cracking.
There are different types of Grounds which are used for repairing and strengthening the masonry structure members.
The selection of the types of grout for the masonry repair work depends upon the compatibility of the grout with the original material.
Types of Injection Grouting
- Polymer Injection Grouting
- Cement Sand Grouting
- Gas-Forming Grouting
- Fibre Reinforced Injection Grouting
- Sulfo-Aluminate Grouting
1. Polymer Injection Grouting
Polymer injection grouting is mainly done with the help of polymers like polyester epoxy, vinyl ester, polyurethane, and acrylic resins.
The polymer is widely used in epoxy grout. Polyurethane and acrylic resin Polymers are generally used for repairing water-retaining structures and underground structures as well as to prevent the seepage of water.
The polymer injection grouting is available in the following grout materials
- Liquid Resin Content
- Curing Agent or Hardener
- Aggregate or Dry Filler
- This types of injection grouting are suitable for concrete repair work.
There are different types of polymer-based injection grouting are available
Types of Polymer-Based Injection Grouting
- Epoxy-Based Injection Grouting
- Acrylic Polymer Based Injection Grouting
- Lignosulfonate Based Injection Grouting
1. Epoxy-Based Injection Grouting
It is non-resistance to ultraviolet exposure and high temperatures non-shrinkable, effective in sealing cracks, and has good bonding with every construction material.
2. Acrylic Polymer Based Injection Grouting
It has improved structural as well as tensile properties and is also resistant to cracking, segregation, and imperviousness.
3. Lignosulfonate Based Injection Grouting
This type of injection grouting help to compensate for drying and plastic shrinkage.
2. Cement Sand Grouting
Cement sand grout is one of the most popular and widely used groutings for the repair of concrete and masonry structures.
This grout is used where strength enhancement of the structures is not essential. It is very easy to use and readily available in the market.
The cement and sand grouting method required a higher amount of water and cement content. The use of cement sand grouting will result in shrinkage and cracking of grouting at the hardening stage.
3. Gas-Forming Grouting
The gas-forming injection grouting basically works on the principle that the gas Bubbles expand the grout to compensate shrinkage of grout after its application.
These types of gas Bubbles will develop a reaction of some ingredients with the cement slurry.
The gas-forming grouts are very sensitive to the temperature so they cannot be used for places where the temperature is very high.
It requires proper confinement in order to develop good strength and volume stability. The reaction forming the gas bubbles is very fast and it will be complete before placing the grout.
4. Fibre Reinforced Injection Grouting
Fibre-reinforced concrete is widely used for repairing concrete structures as well as masonry structural members.
Fibres such as polypropylene, steel, or glass fibres are generally used for Portland cement to repair and strengthen the structural members. Fibre-reinforced injection grouting provides good flexural strength, resistance to impact, and ductility.
This type of injection grouting required skilled labour.
5. Sulfo-Aluminate Grouting
Sulfo-aluminate grouting is based on the principle of shrinkage compensation.
In these types of grouting, shrinkage compensating cement or anhydrous Sulfo-aluminate expansive additives are used.
This helps to produce expansion after the grout has set and it is more reliable than gas-forming grouts.
This types of grouting are not effective if it is not provided with proper moist curing.
Properties of grouting material
- The material which is used for grouting should be non-shrinkable.
- The grouting material should expand when it is filled in the cracks or voids.
- The grouting material should be capable to sustain compressive loads.
- It should have good tensile strength and vibratory load resistance.
- It should richest the entry of moisture and be easy to apply.
Different Types of Grouting Materials
- Cement grout or cement-based mortars.
- Cement sand with additive grouts.
- Polymer Modified cement grout.
- Epoxy resin.
Advantages of Injection Grouting
- Injection grouting is very easy and convenient to use.
- Injection grouting is an environment-friendly process.
- It is suitable for repairing cracks and filling voids in structural members.
- It provides strength and stability to the masonry structural members.
- The injection grouting process is economical.
- There is no wastage of material in the injection grouting process.
Process of Injection Grouting
As per the below processes of injection grouting
- Drilling Holes on the Surface
- Cleaning the Holes and Cracks
- Sealing the Cracks Between the Holes.
- Grout the Hose Connections
- Injecting Grout in the Cracks
Step – 1. Drilling Holes on the Surface
Drill the holes or ports in the cracks at regular intervals. The distance between the two ports depends upon the types of cracks.
For fined cracks, the distance between two ports ranges from 150 mm to 200 mm and the distance between ports in major cracks ranges between 300-400 mm.
Step – 2. Cleaning the Holes and Cracks
Before starting grouting it is very important to clean and flush the cracks and holes properly.
Cleaning can be done manually or by using a vacuum to clean the cracks. The cracks should besprinkle with water.
It is very essential to clean it properly to establish a strong bond and gain maximum strength.
Step – 3. Sealing the Cracks Between the Holes.
The crack between the ports should be filled with epoxy, polyester or cementitious materials.
Allow the seal to harden and then start the further process of grouting.
Step – 4. Grout the Hose Connections
Fix the nipple or pipe in the holes and seal it by applying cement paste around it such that it cannot move from its place.
Step – 5. Injecting Grout in the Cracks
Inject the grout material in the crack or voids with the help of an Injection Grouting machine. It should be filled with pressure.
Injection grouting required skilled labour. The temperature on the site is also considered while the process of grouting.
Applications of Injection Grouting
- It is used to reduce or fill the cracks or voids in the structural members.
- It is generally used for repairing cracks in walls columns and other structural members.
- It is also used for providing finishing to the wall.
- Injection grouting is used to repair damage in the structural or masonry members.
- Injection grouting is best suitable for honeycombing.
- Injection grouting is used to repair and strengthen the damaged areas.
- It is also used for making walls waterproof.