Pressure grouting, also known as injection grouting or cement grouting, is a technique used in construction and civil engineering to strengthen and stabilize soil or rock formations. It involves injecting a fluid material, typically a cement-based grout or epoxy resin, into the ground under pressure.

The primary purpose of pressure grouting is to improve the load-bearing capacity of the soil or to seal voids or fractures in the rock or concrete. It can be used in various applications, such as:

1. Foundation Stabilization: Pressure grouting is often employed to stabilize weak or settling foundations. By injecting grout into the soil beneath the foundation, it fills voids and consolidates loose or soft soil, increasing its strength and reducing settlement.

2. Soil Improvement: In some cases, pressure grouting is used to improve the engineering properties of the soil. The injected grout fills the pore spaces and forms a solid mass, enhancing the soil’s load-bearing capacity, compressibility, and stability.

3. Sealing and Waterproofing: Grouting can be used to seal cracks, joints, or voids in concrete structures, preventing the ingress of water, chemicals, or gases. This technique is commonly employed in underground structures, such as tunnels, dams, and basements.

The pressure grouting process typically involves the following steps:

1. Site Investigation: A thorough investigation is conducted to assess the condition of the soil or structure and identify the grouting requirements.

2. Grout Material Selection: The appropriate grout material is selected based on the project requirements, considering factors such as strength, flowability, setting time, and chemical resistance.

3. Drilling: Access holes or boreholes are drilled into the ground or structure at predetermined locations and depths.

4. Injection: The grout material is injected into the ground or structure through the drilled holes using specialized injection equipment. The injection pressure and flow rate are carefully controlled to ensure proper distribution and penetration of the grout.

5. Monitoring: During the injection process, various parameters such as injection pressure, flow rate, and displacement are monitored to ensure the desired grouting results are achieved.

6. Post-Grouting Verification: After the grouting is completed, post-grouting tests and inspections may be carried out to evaluate the effectiveness of the grouting process.

Pressure grouting is a specialized technique that requires expertise and experience to ensure its successful application. It is commonly performed by specialized contractors who have the necessary equipment and knowledge to carry out the grouting process effectively.