Applicability, Quality Control and
Quality Assurance in Ground
Improvement
Presented by
Kulbir Singh Gill,
Associate Prof. GNDEC,
Ludhiana

INTRODUCTION
 Unfortunately, soils are made by nature and not by
man, and the products of nature are always complex(Karl
Terzaghi 1936).
 The advancement in geotechnical engineering has
provided many alternatives to deal with the problems
encountered during soil investigation for the site selection
of a particular project.
 Since the safety of lives and property are at stake, it is
important to consider the geotechnical merits or demerits
of various sites before the final decision is taken for that
project.
 Moreover risks and costs needs to be evaluated.

Contd.
 Due to the lower value of land to population ratio
in India, it is utmost important to utilize any type
of land available for construction.
 So keeping in view the above stated problem
, different types of ground improvement
techniques are adopted to make the weak soils
suitable to meet the minimum requirement for any
particular project.
 The various types of ground improvement
techniques which are commonly used are:

Contd.
 Improvement by vibro compaction
 Ground improvement using vibro replacement
 Ground improvement using deep soil mixing
 Ground improvement using permeation grouting.
 Improvement by increasing effective stresses.
 Improvement by admixtures.
 Geotechnical reuse of waste materials.
 Weight reduction.
 In this presentation only the applicability, quality
control and quality assurance are covered.

Applicability of the Vibro
Compaction
 This technique is used to increase the bearing capacity
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of foundations and to reduce their settlements.
Another important application is to mitigate the
liquefaction potential in earth prone areas by
densification of sand.
Vibro compaction can be used to support any type of
projects from embankment to chemical plants.
Mainly this technique depends on the granular soil to
be compacted.
So far the deposits down to 65m have been improved
by vibro compaction.

Quality Control and Quality
Assurance
 In general quality control programme is divided into
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categories, namely monitoring of compaction parameters
and post compaction testing.
The compaction parameters(depth and power
consumption) are monitored using computerized systems.
Post-compaction testing is performed to ensure that the
specifications are met.
Dynamic penetrometer tests(DPT),standard penetration
tests(SPT) and cone penetration tests(CPT) is most popular
post compaction test.
At least one week cooling period must be given after the
compaction in order to dissipate the excess pore water
pressure to initial level before compaction.

Limitations
 Vibro compaction technique is most effective for
sands and gravels with fines less than 15 to 20% as
shown in Figure

Applicability of Ground Improvement
using Vibro Replacement
 : The unique characteristic of the vibro replacement
technique is that it is able to treat a vide range of
weak soils from loose silty sands, soft marine
clays, ultra soft silts and clay from mine
tailings, garbage fill to peaty clays.
 The various types of structures which can be
supported soil improved by vibro replacement are
simple earth embankments, modern expressway
embankments, bridge approaches, high speed railway
embankments, marine and offshore
structures, seaport/airport facilities, power plant
structures, chemical plants, sewerage treatment
plants and large storage tanks.
 The basic aim of vibro replacement is to increase the
stability and bearing capacity of weak soil as well as
to restrict the settlement. In earthquake prone areas it
has also been used to mitigate liquefaction potential.

Quality Control and Quality Assurance
in
Vibro Replacement
 In vibro replacement method, quality control monitoring
consists of monitoring of column construction parameters
and post construction testing.
 During construction, the main parameters of the
construction process(depth, vibration energy during
penetration and compaction processes and stone
consumption) are recorded continuously as a function of
time, thus ensuring the production of a continuous well
compacted column.
 The performance of vibro stone columns is assessed using
plate load tests which should be carried out by loading a
rigid steel plate or cast in situ concrete big enough to span
one or more columns and the intervening ground.

Contd.
 . In contrast to the more familiar load tests in
piles, both the column and the tributary area of soil
around the column are loaded.
 In addition, the performance of the treated soil to
support the intended structure is evaluated based on
the results of instrumentation such as rod settlement
gauges, inclinometers, etc.
Limitations:
 Vibro stone columns are not suitable in liquid soils
with very low undrained shear strength, because the
lateral support may be too small.
 In general, the technique is applied to structures with
high order of settlement tolerance.

Applicability of Deep Soil Mixing
 The technology of deep soil mixing can be
implemented on wide range of weak and
problematic soil types such as loose sands, soft
marine clays, ultra soft slimes, weak silty clays
and sandy silts.
 Typical applications include foundation s of
embankment fill for roads, highways ,railways and
runways; slope stabilization, stabilization of cuts
and excavations(Topolinicki,2004 and Raju
et.al., 2005).
 The DSM technology can also be used for
vibration reduction applications and to partially
reduce water paths for water tight applications.

Quality Control and Quality Assurance
of Deep Mixing Soils.
 For both wet and dry deep soil mixing ,quality control
during execution is important to ensure uniform
improvement of soil and to ascertain that the required
amount of binder has been mixed uniformly over the
entire depth of treatment .
 For this purpose, the mixing units are equipped with
automated computerized recording devices to
measure the real-time operating parameters such as
depth of mixing tools, volume or weight of binder used
etc.
 After allowing for sufficient curing period(typically,3 to
4 weeks), the mixed columns can also be tested using
single/group column plate load tests, unconfined
compressive strength tests on cored/backflow
samples, visual examination of exposed columns, etc.

Applicability of Ground Improvement
using Permeation Grouting
 This type of grouting is very effective in sands
gravels, coarser size materials(e.g .boulders and
cobbles) and fissured, jointed and fractured rock
formations.
 The technique is well suited for a wide variety of
applications, such as foundation retrofitting, dam
rehabilitation, subsidence and liquefaction
mitigation etc.
 Applications can be categorized into the following
general areas, site improvement, foundation
rehabilitation, excavation support, ground water
control.(Karol, 1990).

Applicable soil types for Permeation
Grouting

Limitations
 Permeation grouting is not suitable in cohesive soils
such as silts and clays.
 The other types of grouting techniques such as
fracturing grouting and jet grouting can be considered
to improve such soils.

Applicability of Ground Improvement
using Weight Reduction
 This technique involves reduction of weight applied to
a soft compressible soil by the use of light weight fill
material.
 The over all benefits gained from the light fill
materials include reduced settlement, increase in
slope stability and reduced lateral earth pressure on
retaining structures.
 A key benefit is material’s high resistant to earthquake
effects (the low unit weight results in lower seismic
inertial forces).

Light Weight Materials used for
Ground Improvement
Fill Material
Source/Process
Dry Unit Weight (Kg/m3)
Wood fibres
Sawed lumber waste
550-960
Shredded tyre
Mechanical cut tyre chips
600-900
Calm shells
Dredged under water deposits
1100-1200
Expanded shale
Vitrified shale or clay
600-1040
Fly ash
Residue of burned coal
1120-1400
Air-cooled slag
Blast furnace material
1100-1500
Flowable fill
Foaming agent in a concrete matrix
335-770
Geofoam
Block moulded expanded polystyrene
12-32

Quality Control and Quality Assurance in Ground
Improvement using Weight Reduction:
 The key issues with the weight reduction method
of ground improvement are to placement of the
light weight material and its durability and longterm performance.
 Well planned laboratory experimentation is
needed to optimize the use and performance of
light weight materials .
 Durability can be checked in the laboratory.

Limitations
 Some of the material are susceptible to various
types of problems after their placement in the
field, e.g. geofoam can easily catch fire also
deterioration can occur gasoline spills or insect
borrowing.
 Continued crushing and knitting of the shells
during compaction of the shells under the
influence of vehicular traffic may reduce the
drainage potential of embankment.
 Thus resulting in ponding of water at the surface
and also it may reduce the frictional angle of the
material, thus increasing the lateral pressure on
the supporting structures.

Applicability of Ground Improvement
using Admixtures.
 Use of various admixture such as lime, cement, fly ash and furnace slag are
well understood to the geotechnical engineers.
 But recently several environmental friendly enzymes have come into the
market such as Fujibeton, Terrazyme and Renolith etc. These materials are yet
to gain popularity in the field of ground improvement.
 The fujibeton material, developed in Japan, is climatically stable material and
suitable for stabilization of all types of soils. Basically, the product is an
inorganic polymer that chemically binds with all compounds when blended
with OPC in 1 to 3% by weight. The blended mix is called fujibeton mix.
 The technology can be advantageously used in the construction of low volume
roads where aggregates are not available at economical rates but also for all
type of soil conditions
 . Fujibeton improves CBR of the subgade and does not create shrinkage cracks
and is there for highly effective for clayey soils. With fujibeton, a high dry
density is obtained with minimum compaction, therefore simple and small
equipments are sufficient for construction.

Terrazyme
 Terrazyme is a natural, non-toxic, environmentally
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safe, bio-enzyme product that improves engineering
properties of soil.
The function of terrazyme is to minimize absorbed
water in the soil for maximum compaction, which
decreases the swelling capacity of soil particles and
reduces permeability.
The application of terrazyme enhances weather
resistance and increases load bearing capacity of soils
especially in clayey soils.
This will provide cost effective both in the initial
construction cost and maintenance cost of roads.
Terrazyme technology is also advantageous
in:considerable improvement in the soil CBR.Minimum
loss of gravel due to erosion or abrasion by the traffic
preserving original transverse section.

Renolith
 Renolith is a polymer based chemical, which is
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environmentally friendly and facilitates the
bonding of soil mass.
The soil-cement with renolith has a high modulus
of elasticity and can disperse the wheel loads
very effectively.
It is a semi rigid material.
This type of construction does not require
surfacing for low volume roads, since the base
course is stabilized.
It is expected to give good performance with
longevity and reduces maintenance costs and

Quality Control and Quality Assurance in
Ground Improvement using Admixtures
 The design concept is based on the optimization
of admixture quantity for stabilization based on
unconfined compressive strength or CBR test
results determined on the given soil for different
proportions of soil and admixtures.
 After the construction ,core can be taken and
tested for unconfined compressive strength in the
laboratory.
 Limitations: Limited research is available with soil
cement and these admixtures in abroad but
similar studies are yet to be carried out in India

Thanks