---
title: "Stabilization by injection of grouts"
subject: "Foundation Engineering"
chapter: 10
key: "semester_5/foundation_engineering:grouting-stabilization"
source: https://www.bctengineer.com/q/semester_5/foundation_engineering/grouting-stabilization
site: BCT Engineering
---

# Stabilization by injection of grouts

Foundation Engineering · Chapter 10: Foundation Soil Improvements

- Asked in: 2080 Baisakh, 3 marks
- Video: [Soil Stabilization -  C7 - L17  INJECTION GROUTING](https://www.youtube.com/watch?v=LIBi9J7lDZ0) — كورسات هندسية
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/foundation_engineering/grouting-stabilization
- Whole chapter: https://www.bctengineer.com/md/semester_5/foundation_engineering/chapter-10

## Question

Describe the soil stabilization by injection of suitable grouts with its advantages.

## Short answer

Grouting injects fluid grout (cement, chemical, etc.) under pressure into soil voids to bind particles, reduce permeability and increase strength. Advantages: increases bearing capacity, reduces settlement, controls seepage, works in confined spaces with minimal vibration.

## Answer

**Grouting** is the injection of a fluid material (grout) under pressure into soil voids, fissures or cavities. The grout then sets or gels, binding the particles, reducing permeability and increasing strength.

**Types of grout:**

- **Cement grout:** cement-water mixture for coarse sands, gravels and fissured rock.
- **Clay or bentonite grout:** for sealing and filling voids.
- **Chemical grout:** sodium silicate, acrylamide or resins, which have low viscosity and penetrate fine sands.
- **Bituminous grout:** used for sealing.

**Method:** holes are drilled or pipes driven to the required depth, and grout is pumped in stages at controlled pressure until refusal, so that the grout permeates the soil without fracturing it.

**Advantages:**

1. Increases bearing capacity and reduces settlement.
2. Reduces permeability, so it controls seepage under dams and in excavations.
3. Can be done in confined spaces, with little vibration or disturbance to existing structures.
4. Underpins existing foundations without excavation.
5. Fast and works at any depth.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is grouting?
   A. Placing a surcharge
   B. Injecting fluid grout under pressure into voids that then sets, binding particles and reducing permeability
   C. Mixing lime with clay
   D. Dropping a weight on soil
   Answer: B. Grout sets or gels in voids, increasing strength and reducing permeability. (Key point: Definition of grouting)

2. Why is chemical grout used for fine sands?
   A. It is cheaper than cement
   B. It is very viscous
   C. It has large particles
   D. Its low viscosity lets it penetrate fine sands
   Answer: D. Cement grout is too coarse for fine sands, but low-viscosity chemical grout penetrates them. (Key point: Chemical grout use)

3. How is grout pumped?
   A. In stages at controlled pressure so it permeates without fracturing the soil
   B. At maximum pressure to fracture soil
   C. By gravity only
   D. After excavating the soil
   Answer: A. Controlled pressure until refusal avoids fracturing the soil. (Key point: Grouting pressure)

## Related in Foundation Engineering

- [Soil stabilization by admixture](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aadmixture-stabilization) — Foundation Engineering, chapter 10, asked 2×
- [Methods of soil stabilization](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Asoil-stabilization-methods) — Foundation Engineering, chapter 10, asked 2×
- [Bituminous stabilization](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Abituminous-stabilization) — Foundation Engineering, chapter 10

## Related in other subjects

- [Soil stabilization methods and lime stabilized road](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Asoil-stabilization-methods-lime-road) — Transportation Engineering II, chapter 3
- [Soil stabilization, equipment, mass haul characteristics](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Asoil-stabilization-definition-equipment-mass-haul) — Transportation Engineering II, chapter 3
- [Soil stabilization methods; soil cement construction](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Asoil-stabilization-methods-soil-cement-road) — Transportation Engineering II, chapter 3
- [Soil stabilization factors; mechanical; cement-soil base](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Asoil-stabilization-factors-mechanical-cement-soil) — Transportation Engineering II, chapter 3