Subject: Ground improvement Techniques Class: IV-1
(Two mark Questions)
UNIT - 2 Grouting
1. Explain grouting?
Grouting is a technique to inject various types of grout into the ground at a
deliberately controlled pressure and flow rate.
The grout is based on cement, silicate, or other materials, selected to suit
particular ground conditions and improvement objectives.
The grout fills in voids and cracks of the ground and permeates into soil
pores to produce a solidified soil-grout mass.
The grouting is often applied to improve the ground underneath existing
structures such as large oil tanks, railroad tracks and others. Directional
drilling technique is often employed for drilling boreholes to circumvent
underground obstructions to reach the target improvement zone.
2. What are the advantages of grouting?
Can be performed on almost any ground condition
It doesn't induce vibration and can be controlled to avoid structural damages
Improvements to ground formations can be measured
Very useful for confined spaces and low headroom applications
Used for slab jacking to lift or level distorted foundations
Can be installed adjacent to existing walls
Can be used to control seepage, groundwater flows and hazardous waste
plumes
3. What are the characteristics of a well graded grout?
No shrinking.
Nonmetallic.
Develops high early strength.
Impact resistant.
Flows without pocketing.
Excellent bond to metal.
Nonconductive.
Non staining.
3. What are the different ways to introduce grout into the soil?
A. Three Ways Of Introducing Grout Material Into The Soil Are Possible:
Permeation Grouting: Grout Fills The Soil Pores. Essentially no change in the
volume or structure of the Original Ground.
Displacement or Compaction Grouting
Hydraulic Fracture or Encapsulation or Squeeze Grouting
4. What are the applications of grouting?
leveling the structure or strengthening the foundation
seepage control
soil solidification and stabilization
Grouting for anchors
Vibration control
5. What are the different methods of grouting?
A. Categories of Grouting
Penetration grouting or Permeation grouting
Displacement grouting
Compaction grouting
Grouting of Voids
Jet grouting
Electro grouting
6. What is Penetration Grouting?
A. This method describes the process of filling joints or fractures in rock or pore
spaces in soil with a grout without disturbing the formation
7. What is Compaction Grouting?
A. Grout mix is specifically designed so as not to permeate the soil voids or mix
with the soil. Instead, it displaces the soil into which it is injected.
8. What is Jet Grouting?
A. The high-pressure water or grout is used to physically disrupt the ground, in the
process modifying it and thereby improving it
9. What is Displacement Grouting?
A. Displacement grouting: It is the injection of grout into a formation in such a
manner as to move into the formation, it may be controlled, as in compaction
grouting or uncontrolled. As in high pressure soil or rock grouting which leads to
splitting of the ground, also called hydro fracture.
10. What is Grouting of voids?
A. Using this process, grout is pumped under pressure into a void beneath a
structure. The cavity might have been caused by a water supply or drainage line
break where the soils have been washed away.
Ideal for situations during new construction or machine placement where a void
cannot be easily filled without extensive rip out. To account for proper travel and
strength qualities, the grout mix is custom-designed for each application.
11. What is Electro Grouting?
A. Electro grouting is a term used for promoting electrochemical hardening during
electro osmosis by adding chemicals, such as sodium silicate or calcium chloride, at
the anode. Under the influence of the electric field, these chemicals permeate the
ground, flowing in the direction of the cathode, while the anode becomes a grout
injection pipe.
Subject: Ground improvement Techniques Class: IV-1
(Two mark Questions)
12. How is the grout mixes classified?
A. The grout mix can be generally classified into four types:
mortar and pastes such as cement to fill in holes or open cracks
suspensions such as ultra-fine cement to seal and strengthen sand and joints
solutions such as water glass (silicate) and
emulsions such as chemical grout.
13. Give some of the commonly used suspension grouts used
grouting with soil
Grouting with cement mixes
Grouting with asphalt emulsions
14. Give some of the commonly used solution grouts used
silicate derivatives
Lignosulphite derivatives
Acrylamides
Phenoplast resins
15. Give the list of grouting equipment
Drilling Equipment
Shotcrete
Grouting Bolts
Mixing
Tunnel Boring Machine (Tbm)
16. Define the stages in grouting
A. Descending method and Ascending method
In descending method, impregnation of the ground occurs in advance of the
borehole, which is advantageous in loose soil or rock.
In ascending technique, grouting follows drilling as a separate phase.
17. Write a short note on post grout test.
A. Post Grouting of anchors can significantly improve the load carrying capacity of
anchors in cohesive soils by increasing the skin friction of the anchor grout body
with the soil.
18. State the different injection methods in grouting
grouting from the bottom
grouting from the top
circuit grouting
point grouting
jet grouting
electro kinetic injection
19. Explain briefly about soilcrete
Soilcrete is a method of rendering better engineering properties to the
foundation soil
In this method of soil stabilization, soil is mixed with Portland cement and
water. The mixing is done in situ by excavating soil and mixing it with
cement and water by blending with mechanical mixer and sometimes fluid is
injected in high pressure.
Soilcrete is used in either grid pattern or in pinpoint where concentration of
structural loads is high. The first option is used where entire substructure are
needed to be treated to provide foundations like slab foundation or storage
tank.
The foundation bed that have soft or loose deposits, suspected to be suffered
excessive settlement
Subject: Ground improvement Techniques Class: IV-1
(Two mark Questions)
20. Explain hydraulic fracturing?
A. Geologic formations may contain large quantities of oil or gas, but have a poor
flow rate due to low permeability, or from damage or clogging of the formation
during drilling. This is particularly true for tight sands, shales and coalbed methane
formations.
The technique of hydraulic fracturing makes use of a liquid to fracture the reservoir
rocks. A hydraulic fracture is formed by pumping the fracturing fluid into the
wellbore at a rate sufficient to increase pressure down hole to exceed the strength
of the rock.
Hydraulic fracturing stimulates wells drilled into these formations, making profitable
otherwise prohibitively expensive extraction.
(a) Explain how pre-wetting technique is useful in improving the properties of the
soil.
(b) Write a note on grouting methods.
(a) Write a note on post grout test.
(b) Write a note on types of grouting.
(a) Explain how pre-loading technique is useful in improving the properties of the
soil.
(b)Write a note on objects of grouting.
(a) Explain how sand drains are effective in improving the properties of the soil.
(b) Write a note on thermal stabilization.
What are the functions of stone column discuss its installation techniques with neat
sketches. [8+8]
b) What is Vibro Flotation? Explain the principle of Vibro Flotation with neat
sketches.
Explain in detail soil stabilization by grouting
Describe the equipment used in grouting technique
Describe different grouting techniques depending upon stabilizer used
Write short note suspension and solution grouting
What is grouting? Explain in detail methods of grouting
RAGHU ENGINEERING COLLEGE
DEPARTMENT OF CIVIL ENGINEERING
Subject: Ground improvement Techniques Class: IV-1
(Two mark Questions)
Describe grouting and explain in detail field of applications?
Explain situations where grouting technique is adopted
Considering the groutability of various types of soils, what method do you
recommend grouting fine grained soils? Discuss in detail with neat sketches.
2. a) Explain any three engineering application of grouting which proves to be
effective? b) Write a note on suspension and solution grouting techniques and their
effectiveness in improving the in-situ soil conditions. [8+8]
2. a) What do you understand soil stabilization by grouting? Explain in detail
various field of applications of grouting. b) Describe in detail the grouting with ‘soil-
cement mixes’, ‘cement’, and ‘lime’ grouts. [8+8]
2. a) What is grouting? Explain in detail various field of applications of grouting. b)
Explain compaction grouting, penetration grouting and fracture grouting with neat
sketches. [8+8]
