Ground Improvement

through

GROUTING

Department of Civil Engineering,

NIT, Jamshedpur

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Grouting & Types

of Grouts

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Grouting1. Grouting is the process to inject grout into the ground. Hence, the

volume of the ground ready to accept grout is the primary consideration

before any other considerations.

2. GROUT can be defined as a solution, an emulsion or suspension in water,

which will harden after a certain time interval. It can be divided into two

main groups:

a. Suspension Grout

b. Liquid Grout or Solution Grout.

3. Suspension grout is a mixture of one or several inert materials like

cement, clays etc. suspended in a fluid -- water. According to its dry

matter content it is either of the stable or unstable type. suspension grout

is a mixture of pure cement with water.

4. Liquid grout or solution grout consists of chemical products in a solution

or an emulsion form and their reagents. The most frequently used

products are sodium silicate and certain resins.

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GROUTING

1. Grouting is a process of ground improvement attained

by injecting fluid like material into subsurface soil or

rock.

2. Grouting is the injection

• specially formulated cement of stable suspensions or

• liquid into pores, fissures or voids, or

• the jetting of cement mixtures at

• high flow rate and pressure into the soil to create

soil- cement to increase the strength.

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Types of grout

• Numerous materials have been developed for use as

grouts.

• All have the property of fluidity, but this can be of

materials as diverse as thick pastes and mortars,

slurries, colloidal suspensions in water, emulsions of one

liquid in another, solutions, liquid resins and, even.

suspensions of very fine solids in gases.

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Types of grout1. Mortars and pastes (usually a combination of cementitious material and

filler)

2. Cement slurries and suspensions in water

3. Cement-bentonite suspensions in water

4. Bentonite (or other clay) colloidal suspension in water

5. Microfine cement colloidal suspensions in water

6. Chemical solutions usually in water

7. Chemicals in a colloidal system that form gels

8. Resins, ie organic chemicals.

• The thicker grouts are used for void filling, jet grouting, compaction

and squeeze grouting.

• The intermediate and colloidal suspensions are often used for

hydro-fracture.

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ADMIXTURES for Cement Grouting

Common admixtures used with cement grouts:

1. Calcium chloride ]

2. Sodium hydroxide ]---for accelerating setting time

3. Sodium silicate

4. Gypsum

5. Lime sugar

6. Sodium tannate

7. Fine bentonite

8. Clay

]

]

]---for retarding setting time.

]

]

]

9. Ground shale

10. Rock flour

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]---for reducing cost of grout & reduces

] strength of grout

The assessment of

groutability

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The assessment of groutability

• Grouting, for whatever purpose, affects the void spaces of the

ground either to fill them or to reduce their volume.

• The groutability of the ground is not a single or fixed characteristic,

but depends on the

• purpose of the grouting,

• the technique and the grout, as well as,

• the nature of the ground and its voids.

• Different techniques or combinations of techniques with different

grouts can achieve the same purpose. Very broadly, however, the

grouting processes associated with different types of ground are

shown in Table next.3/27/2020

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What grouting does?

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Why grouting is required?

• There are nine main reasons for using grouting as the means of

ground improvement

1. Reducing the permeability of the ground.

2. Providing a barrier or cut-off to water flow in the ground.

3. Increasing the strength of the ground to permit its safe excavation.

4. Increasing the strength, stiffness and bearing capacity of the ground.

5. Increasing the overall density of the ground.

6. Infilling natural cavities.

7. Infilling mineral workings.

8. Infilling voids adjacent to structures.

9. Compensating for ground loss caused by adjacent works.

• The above list shows the versatility of grouting techniques, made

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List of few applications of grouting in Civil Engineering

1. FILLING VOIDS TO PREVENT EXCESSIVE SETTLEMENT

2. TO INCREASE ALLOWABLE PRESSURE OF THE SOIL BOTH FOR NEW STRUCTURES AND / OR

ADDITIONS TO EXISTING STRUCTURES.

3. CONTROL OF GROUNDWATER FLOW

4. PREVENTION OF LOOSE - LOOSE TO MEDIUM SAND DENSIFICATION UNDER ADJACENT

STRUCTURES (I.E. BOTH FOR VERTICAL AND LATERAL MOVEMENTS) DUE TO ADJACENT

EXCAVATIONS, PILE DRIVING ETC.

5. GROUND MOVEMENT CONTROL DURING TUNNELING OPERATIONS

6. SOIL STRENGTHENING TO REDUCE LATERAL SUPPORT REQUIREMENT

7. SOIL STRENGTHENING TO INCREASE LATERAL AND VERTICAL RESISTANCE OF PILES.

8. STABILIZATION OF LOOSE SANDS AGAINST LIQUEFACTION

9. FOUNDATION UNDERPINNING

10. SLOPE STABILISATION

11. VOLUME CHANGE CONTROL OF EXPANSIVE SOILS THROUGH PRESSURE INJECTION OF

LIME SLURRY (ONLY FOR SOME EXPANSIVE SOILS NOT ALL)

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History of Grouting

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History of Grouting in Civil Engineering• Its traceable record can be as early as in the beginning of 1800s.

• In 1802, the idea of improving the bearing capacity under a sluice by the injection of

self-hardening cementitious slurry was first introduced

• In 1864, Peter Barlow patented a cylindrical one-piece tunnel shield which could fill

the annular void left by the tail of the shield with grout. It is the first recorded use

cementitious grout in underground construction.

• In 1893, the first systematic grouting of rock in the USA as performed at the New

Croton Dam, in New York.

• In 1960s, jet grouting technique was developed.

• In 1977, first application of compaction grouting for controlling ground movement

during construction of the Bolton Hill Tunnel.

• In 1995, the first industrial application of the compensation grouting concept was

conducted at the construction site of the Jubilee Line Extension Project in London.

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Few Visuals for

Grouting

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3

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Pile walls and grouting

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Safety can be

brought back by

grouting3/27/2020

Grouting to regain the

safety of the Foundation

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Grouting Process

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GROUTING PROCESSES

• Grouting methods be classified by process rather than

by grout material or end result. Accordingly Grouting

can be of types below.

1. Permeation grouting

2. Hydro-fracture grouting

3. jet grouting

4. Cavity infilling

5. Compaction, squeeze and compensation grouting

These main processes of Grouting are explained in the

sketches to be followed

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GROUTING PROCESSES - Contd.

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GROUTING PROCESSES - Contd.

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GROUTING PROCESSES - Contd.

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GROUTING PROCESSES - Contd.

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Grouting Explained through

Pictures and Videos

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Steps in Grouting

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Cement grouting, also known

as slurry grouting or high

mobility grouting, is a grouting

technique that fills pores in

granular soil or voids in rock or

soil, with flowable particulate

grouts.

Depending on the application,

Portland cement or microfine

cement, grout is injected

under pressure at strategic

locations either through single

port or multiple port pipes.

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Chemical grouting is a grouting

technique that transforms

granular soils into sandstone-like

masses, by permeation with a

low viscosity grout.

The soils best suited for this

technique are sands with low

fines content.

The grout permeates the soil

and solidifies it into a

sandstone-like mass. The

grouted soil has increased

strength and stiffness, and

reduced permeability.

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Compaction grouting, also

known as Low Mobility

Grouting, is a grouting

technique that displaces

and densifies loose granular

soils, reinforces fine grained

soils and stabilizes

subsurface voids or

sinkholes, by the staged

injection of low-slump, low

mobility aggregate grout.

The expansion of the low

mobility grout bulbs displaces

surrounding soils. When

performed in granular soil,

compaction grouting increases

the surrounding soils density,

friction angle and stiffness.

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Compensation

Grouting or

Fracture Grouting

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Fracture grouting, also

known as compensation

grouting, is a grouting

technique that hydro-

fractures in situ soil.

Once the hydro-fracture

pressure of the soil is

exceeded, fractures open

up in the soil and are

immediately expanded by

the subsequent influx of

grout.

The process results in

controlled heave of the

overlying soils and

structures. The technique

has been used to re-level

structures.

Jet grouting is a grouting

technique that creates

in situ geometries of

soilcrete (grouted soil).

The jets erode and mix

the in situ soil as the drill

stem and jet grout

monitor are rotated and

raised.

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Cavity infilling

grout

The grout is injected

under low pressure

through a predrilled

hole. The grout then

expands to fill the

crack or void.

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Typical equipment layout for grouting

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Thank You

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