demolition waste thesis

CHAPTER -1

INTRODUCTION

1.1 General

Soil comprises of various elements,compounds,gases,liquids and endless bacteria,organisms that

are dependent on soil.It is important part of life cycle as food , housing ,agriculture,water storage

are hugely impacted by it.Soil is refered as Earths skinwhich is a essential link between

atmosphere and biosphere. Soil continously is in development mode from one phase to another

by means of various chemical,biological and physical processes.

Soil behaviour is of great importance and it is the reason human race exist on planet earth.Soil

mixed with various other materials was used as a great construction material in ancient and used

in modern age as well. Clay exhibit generally undesirable engineering properties. It tend to have

low shear strengths and to lose shear strength further upon wetting or other physical disturbances.

It can be plastic and compressible and they expand when wetted and shrink when dried. Some

types expand and shrink greatly upon wetting and drying. Cohesive soils can creep over time

under constant load, especially when the shear stress is approaching its shear strength, making

them prone to sliding. Clay develop large lateral pressures and tend to have low resilient modulus

values. For these reasons, clay is generally poor materials for foundations.

For many years admixtures such as lime, cement and are used to improve the qualities of readily

available local soils. Laboratory and field experiments have confirmed that the addition of these

admixtures can increase the strength and stability of such soils. However, the cost of introducing

these admixtures has also increased in recent years. This has opened the door for researchers to

find alternate admixtures such as Molasses,plastic, fibers, liquid enzymes, micro bacteria etc.

Soil is the cheapest construction material available and its been used since ages.Our ancestors had

realized effectiveness of soil as a binding and construction material.Soil properties can ve altered

by addition of various admixtures and waste available naturally or man made.India has large

diversity in weather,climate, region, topography due to which there is diversity in types of soil

available which makes it important to study the behaviour of soil. A large part of Central India is

covered with black Cotton Soils. Black soil covers approximately 30% of total soil mass area in

India.

Black Cotton Soil: Black soil is formed from Basalt or Trap rocks by physical and chemical

decmposition of heavy rocks.When Surface of large mass of rocks are exposed to atmosphere

for a period of time various chemical and physical processes lead to formation of soil.Black soil

is best suited for growing cotton crops that is why it is commonly know as Black Cotton

Soil.This type of soil is particularly clay of high plasticity having very low shearing strength

and low bearing capacity. Such soils swell in significance when soil comes in contact with

moisture and shrink in absence of it. Such soil of expansive nature in India is mainly the BLACK

COTTON SOIL. The expansive nature of such soils is due to the reason that Montmorillonite

mineral is present .

Montmorillonite has basic structural unit consisting of an alumina sheet sandwithced between

two silica sheets.Sucessive Structural Units are stacked over one another like leaves of a

book.The thickness of each structural unit is about 10A. The decomposition of silicate minerals in

the rock leads to formation of clayminerals such as kaolinite, illite and montmorillonite.These

clay minerals are hydrated aluminum silicates and hydrous oxides of aluminum, magnesium and

iron in a crystalline form of relatively complicated structure.

Molasses:Molasses is thick syrupy brown liquid which is produced as a waste during

processing of sugar cane in sugar mills.It contains high amount of Sucrose upto 40% which is

chemically C12H22O11.Sucrose contains Hydroxyl Group(OH+

) which bonds with negitively

charged clay particles.Its melting point is 186 C.Molasses is acidic in nature due to which it is

considered a pollutant for land.Molasses has binding properties which makes it suitable to be

used as stabilzing agent for geotechnical works. Utilising molasses for stabilising expansive clay

shows promising results and it can solve problem of environment as well. The purpose of

molasses in this case was to minimize the moisture loss during the construction of pavement

layers. That means molasses in this case acted as a moisture content sustainer for

soilaggregate.The sustenance of moisture content was caused by hygroscopic properties of

molasses.

1.2 Need to Stabilize the soil

Soil behavior is function of its morphology and minerals present in it. Every year India faces

huge lose in terms of failure of structures like roads, buildings, embankments constructed on

expansive soils. Construction activities on Black cotton soil has always been a challenge for

Geotechnical engineers therefore, lots of effort has been put in to stabilize such soil with various

admixtures and waste materials. To evaluate the performance of soil at micro level studies like

XRD and SEM are much needed to identify the changes in soil structure due to stabilization.

Micro level study offers better understanding of the soil behavior at nano scale level.

Soil is highly unpredictable and heterogeneous material unlike steel and concrete.

Soil properties not only varies from place to place but also varies with depth of

excavation.It also depends upon environmental ,drainage and loading conditions.

Soil properties depend on various engineering parameters and it is difficult to predict soil

behaviour two or three parameters alone.Intensive testing is needed to determine soil

properties.

As huge quantity of soil is involved it is not feasible to transport soil or replace soil.So it

is recommended to stabilise soil in the form it exists on site.

Soil failure may result in heavy loss of life and property as black soil has low bearing

capacity, high compressiblity and high plasticity index which makes it unsuitable for

engineering works.

Use of binding materials like industrial waste,lime,molasses etc to stabilise weak mass of

soil into good construction material is very cost effective which shortens construction

period.

With decreasing resources and land area it is important to re-use waste material in

geotechnial engineering works.Using waste material will have great benefits for

environment as well.

1.3 Significance of Study

More than 30% of central india is covered with Black cotton soil which is expansive in

nature due to presence of montmorillonite mineral which posses great threat to life &

property as it expands with absorption of water and applies swelling pressure which can

be as high as 400 to 500 kn/m2.So there is urgent need to find out ways which are less

time consuming, cheaper and effective to stabilize the soil.

In the present study molasses has been used as an adhesive for Black soil because the

study should be such that it utilises industrial or any other waste so that there is no need to

worry about disposing off the waste.Molasses is also a industrial waste from sugar

indsutry ,it causes land degradtion by decreasing the Ph value of land,soil and makes it

unfit for vegetation by making land acidic in nature. Utilising molasses for stabilising

expansive clay shows promising results and it can solve problem of environment pollution

as well.

1.4 Research Objectives of the Study

The principle objective of this research work is: -

1. The purpose of this research is to see the effectiveness of molasses in enhancing strength

and reduce swelling pressure of expansive soil.

2. To study the effect on unconfined Compressive Strength of Black Cotton Soil mixed with

molasses (in different proportion).

3. To observe the Load-Settlement behavior Black cotton soil and Soil mixed with molasses

using a Finite Element Method Software (Optum-G2).

4. To Study change in morphology of expansive clays due to addition of molasses using

Scanning Electron Microscopy

5. To find the optimum %age of molasses for maximising strength and minimising swell

pressure.

1.5 METHODOLOGY

In the present study, following steps are to be followed to achieve the identified objective: The

quantity of the molasses added will be (2%,4%, 6%, 8%, and 10%) by weight of the soil.

1. Determine the Atterberg limits of virgin soil and BC soil mixed with molasses in different

%(2,4,6,8,10).

2. Determine the Optimum moisture content and Maximum dry density of soil by standard

proctor test of each set of soil molasses mix.

3. Determine the Unconfined Compressive Strength Parameters by UCS test of virgin and

soil mixed with molasses.

4. Determine the Swelling pressure of soil and soil mix by swelling pressure test.

5. Determine values of engineering parameters E,c, by carrying out Triaxial test on

Black Cotton soil and optimum molasses mix.

6. Develop a numerical modelling of footing retained on Black cotton Soil and optimum soil

molasses mix .

7. To find the load carrying capacity of fotting and settlement of Black Cotton soil and

optimum mix.

Table 1 (a): Mix Proportions

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter introduces the significant literature related to improvement of Black Cotton Soil

using a natural polymer (Molasses).Molasses stabilization is comparatively a new concept with

very limited work available on the topic, which opens new doorways of possibilities for

researchers. Molasses availability is also in abundance as India is amongst few largest producers

of sugar in the world. As previous work has shown molasses as a stabilizing agent can be very

effective.

Molasses is a great adhesive having net positive charge due to presence of (OH) hydroxyl group

in its structure.Net positive charge is capable of attracting negative charged clay particles to form

a better intermolecular bond thereby increasing strength and stability of expansive clays.

As molasses forms a coating around the soil grains which increase the soil grain size to reduce

the clay size particles and makes easy sharing of ions between the double diffused layers, which

makes a more flocculated soil structure.

On the other hand if molasses is added more than a specified limit coating formed is so thickened

that it pushes the soil grains apart, which decreases electro static attraction between the soil

particles that the effect of molasses starts reducing forming a less stable and soil with low

strength.

2.2 Literature survey

Koranne, S.S. and Shirsavkar, S.S. (2010) studied the viability of molasses to improve the

strength of weak soil and reduce dust-using molasses. He conducted CBR test on various

proportions of molasses mixed with soft Murum. Molasses % ages used for modification were

5%, 5.5% 6.0%, 6.5%, 7.0% and 7.5%. CBR value was maximum for 6.5% molasses mix with

soft murum. At 6.5%, ratio density increased to maximum thereby increasing the strength of soil.

In addition, plasticity index reduced for this ratio of molasses. He also studied the cost

optimization of sub grade using molasses. He observed molasses mixed in optimum quantity

saves cost from 15% to 40% as compared to conventional design for road.

MNdegwa, Julius. K. examined the mechanism of stabilization of expansive soil with cane

molasses. He observed that with addition of molasses the swelling pressure of Black cotton soil

reduced considerably. He conducted CBR test on soil molasses mix with varying %age of

molasses from (2 to 14)%. He examined reduction in swelling pressure is due to increased silt

and sand content and less clay content. This is due to the flocculated soil particles due to the

cation exchange process between the cations of molasses and easily exchangeable cation on soil

surface. Molasses has tendency to enhance flocculation and stability of soil aggregate as it has

adhesive properties due to presence of hydroxyl group (OH) which is mainly responsible for

properties of sugar and molasses. Hydrogen bonds are intermolecular in nature and have net

positive charge on them, which makes the molasses adhesive in nature and binds the soil particles

together thereby increasing the stability of expansive clay as clay particles are negatively

charged. Also the Expansive soil mixed with molasses provided higher CBR values with huge

reduction in swelling tendency of Expansive clay specimen. 6.5 % age of molasses by weight of

soil provided highest CBR value in the range of (0-8) % molasses with less swelling tendencies.

Above 8% percent, CBR values tend to fall due to thickened clay particles. With increased

coating of molasses on soil grains gap between the soil grains starts widening again because of

which intermolecular bond becomes weak.

Adel, D.et al., have used the analytical studies and software (Plaxis) to show that deformations

were mainly in the area direct in contact with the pavement under traffic. From odometer test

swelling pressure found was 350kn/m2 .the research does analytical study of pavement on

expansive soil along with suggest possible preventive measures to have minimum effect of it on

pavement. Surface cracks on pavement are visible due to shrinkage of expansive clay .the result

compiled from the simulation were checked on various soil models like Mohr coulomb on

pavement, soft soil in sub grade. Combination of both model depicts major displacements are in

shoulder of sub grade course with consolidation value 44.26x10-3m.subgrade acted like hard

elastoplastic soil while pavement acted non-linear elastoplastic soil. The suggested stabilization

technique for cyclic motion of expansive sub-grade is application of surcharge fill equivalent to

swell pressure.

Bose, Bidula observed that on addition of fly-ash plasticity Swelling character of expansive clay

are reduced as well as reduction in plasticity index and linear shrinkage was noticed. He

conducted swelling test, SEM test and found Fly ash has potential to stabilize expansive clay like

Bentonite because it has low unit weight, low specific gravity, easily compactable, good

coefficient of friction makes it highly desirable stabilizing agent. Fly ash decreased OMC with

increasing content of it where as max dry unit density was observed at 20% fly-ash mix in soil.

The result of unconfined compressive test is maximum at same content of fly ash where dry

density was maximum.UCS value shows increase at 20% fly-ash mix up to 40%.

Ravi, E.et al., Aim of the study was to carry the experimental investigation to study the

effectiveness of liquid stabilizing agent molasses in improving shear strength and CBR of highly

compressible clay. Basic experimental tests conducted were Atterberg limit test, Proctor test, free

swell, Specific Gravity test. Plasticity index came out to be 28%, free swell value was 32% and

specific gravity value was 2.8 for Virgin Black cotton soil. Proctor Test showed decline of MDD

with increasing % of molasses (0 to 12%) and same trend was seen for OMC as well. Molasses

quantity needed in maximizing the strength parameter was 6.5%.At optimum % value of UCS

increased up to 60% which was 91.6kn/m2

for virgin soil sample. Molasses enhanced cohesion

value of soil, which resulted in increased UCS and resisted CBR penetration.

Agarwal, Puneet.et.al., observed UCS trend of Expansive clay when treated with Bioenzymes

like Terrazyme, which is a natural, non-toxic liquid produced by vegetable extracts. These

additives reduce voids in soil particles and maximize compaction. They also have tendency to

control swelling behavior of expansive clays. The UCS test conducted on various dosages of

Terrazyme (0ml, 0.25ml, 0.5ml, 1ml, 2ml, 3ml) for 5kg sample of Black cotton soil showed

180% increase in UCS value for 1 day curing and 200% increase for 7 day curing. The optimum

percentage of Terrazyme came out to be 1ml/5kg of soil. He concluded that Terrazyme can be

used for any type of soil and its application is easy which assures safety for environment as well.

Duration of curing plays huge role in maximizing strength values of UCS , it can be as high as

200% of virgin black soil UCS value.

Bhavsar, Sachin.et.al. studied viability of marble powder and brick powder in controlling

swelling and shrinkage of black soil. The % of marble & brick powder selected was 40 and tests

performed were Atterberg limit test, linear shrinkage test and swelling test. Plasticity index of

black soil reduced from 26.1 to 19.93 on 40% addition of marble powder and for brick powder, it

reduced to 19.72.Linear shrinkage was 23.7% for black soil initially which dropped to 5& 7.8 for

marble and brick powder. Results of Differential free swell showed that marble powder is perfect

in stabilizing black soil as free swell was 0% in case of marble powder which was 50.50% for

virgin black soil sample. Marble powder gave better results as it is fine, less plastic and grated

well.

Parate, kanak.et.al. observed the effectiveness of fly ash through lab tests like CBR,Proctor test,

Atterberg test, specific gravity test in stabilizing black cotton soil. He conducted lab results to

estimate thickness of sub-grade of pavement to be built on black soil. Since it is not possible to

replace locally available soil it is better to stabilize on site. Flexible pavement faces huge

deformation due to loads, swelling pressure, which finally fails the sub grade or pavement. The

ratios of fly ash used varied from 10 to 50%. MDD is highest at 20% fly ash mix with soil. CBR

test values confirm the 20% fly ash gives higher value of CBR, which is as high as 22.90% then

virgin black soil.

Mahiyar, H.K.et.al. conducted experimental study on Black cotton soil + fly ash ,coconut coir

fiber mix and carried out study on swelling behavior ,CBR value of Black cotton soil mixed with

coconut fiber ,Fly ash . The study evaluates the effect of coconut fiber + soil mix for some

engineering properties of Black soil like plasticity index, compaction characteristics and CBR

value of Black cotton soil. Different proportions used for the experimental prog. varied from 10

to 25 % for fly ash and 0.25 to 1% for coconut fiber. The optimum percentage is 20%fly ash +1

% coconut fiber + Black cotton soil which showed CBR value of 5.2 and swelling pressure

reduced to 1/10th

of value of virgin Black soil. Black cotton soil experimental results showed

swelling pressure of 3.5kg/cm2

for virgin sample and free swell value was 30%.He concluded

the coconut fiber used with fly ash in Black cotton soil increased CBR value from 1.5 to 5.2 and

reduced swelling tendencies of Black cotton soil up to 90%.

Annadurai, R.et.al. Studied particle size distribution of soil sample F1 contained 70% clay, 28%

silt and 2% sand and soil sample F2 contained 66% clay, 32 % silt and 2% sand. The specific

gravity of the soil sample F1 and F2 were 2.23 and 2.37 respectively. Tests for Geotechnical

properties of both the soils F1 and F2 were conducted as per the BIS and the test results are

shown in the Table 1. From the results obtained, it was identified that both the samples were

highly compressible clays.Phospho Gypsum (PG) is a by-product in the wet process for

manufacture of ammonium phosphate fertilizer by the action of sulphuric acid on the rock

phosphate. The phosphogypsum used in this study had SiO2 - 3.9%, CaO - 32.27 %, and Loss on

ignition of 16.5%.Fly Ash (FA) used in this study was collected from Neyveli, Tamil Nadu. It is

classified as Class F type as per the ASTM Standard C618, and it contained SiO2 - 35.2%,

Fe2O3 - 6.83%, Al2O- 27.4% and CaO - 19.2%. To find the effect of stabilization on soil

samples, PG varied from 2 to 6 percent with 5 percent FA by dry weight of soil was thoroughly

mixed with pulverized clayey soil samples and then mixed with distilled water for preparing

specimens to conduct the CBR tests. The effect of admixtures on CBR of soil mixes were

studied, after keeping the prepared samples for 3 and 7 days curing time before testing. After

testing, the specimens were air dried and pulverized, then free swell index, SEM analysis, EDS

and XRD were carried out to determine the swell characteristics and microstructural changes.

Addition of admixture on soil gives a minimum improvement of CBR to a range of 7.5 8.5

from 1.4 - 2 for the both the soils used in this study. CBR values also increase with the increase

in curing periods. Free swell index of treated soil reduced by around 50% on addition of FA and

PG in both the soils at the curing period of 7 days. The results obtained from strength test were

compared with SEM investigations, the addition of relatively small amounts of stabilizers shows

noticeable changes in the cementatious formation in soil.

CHAPTER 3

EXPERIMENTAL INVESTIGATION

3.1 Experimental Program Introduction

This chapter provides a detailed description of the materials used in the experimental program

and experimental methods used in this study. The experimental program consists of laboratory

tests on virgin Black cotton soil and mix with molasses to characterize the properties such as

Unconfined Compressive Strength, Swelling Pressure,Differential free Swell

SEM -EDS (scanning electron microscope) test is conducted to know the chemical composition

of Black cotton soil, to study its surface morphology and soil structure.

XRD (x-ray diffraction) test is conducted to detect the presence peak of Montmorillonite mineral

at different diffraction angle and intensity.

3.2 VARIOUS TESTS:

The following tests were performed for present study-

1. Casagrandes Test for liquid limit

2. Plastic Limit test

3. SEM-EDS(scanning electron microscopy) for morphology

4. XRD TEST for determination of montmorillonite mineral

5. Pycnometer Test for specific gravity

6. Standard Proctor Test for determination of O.M.C and M.D.D

7. Unconfined Compressive Strength Test

8. Differential free swell

9. Swelling pressure test

10. Unconsolidated Undrained Triaxial Test

11. Optum-G2 software for load settlement curve

3.2.1 SEM-EDS Test: An Oven dried sample for 7 days was passed from 75micron sieve to get

the maximum clay minerals for the test. Sample was oven dried properly to make the sample

crystalline and avoid any presence of water molecule during the test. A sample as low as 2gm is

needed for the test.

SEM (Scanning Electron Microscope) test determines the surface morphology of sample by

providing images at various magnifications and EDS is a software which determines the

percentage of various elements available on surface of the sample magnifications. When

electrons are bombarded on the gold coated soil sample ,the beam is reflected back which gives

images of structural arrangement of sample.SEM has magnification range upto 300000times the

normal image.Gold coating is done on sample to increase conductivity especially on surface to

have better imaging. Non conductive specimens have tendency when bombarded with electron

beam to accumulate electron charge which might cause scanning faults. Therefore, ultrathin gold

coating on specimen with high vacuum evaporation machine.

3.2.2 XRD Test: An Oven dried sample for 7 days was passed from 75micron sieve to get the

maximum clay minerals for the test. Sample was oven dried properly to make the sample

crystalline and avoid any presence of water molecule during the test. A sample as low as 2gm is

needed for the test.

XRD determines the chemical composition of the material in terms of compounds present as well

as constituting elements of the materials.XRD shows the plot between intensity and 2 angle for

the sample where peaks for the constituting compounds or elements of the sample can be seen at

various angles.

Table 3.1:Lab test as per Indian Standards

OPTUM-G2 ANALYSIS: It is a Software based on Finite element method program made for

analysis of deformation and stabililty in geotechnical engineering.the software is designed to be

user friendly with efficient working.It has various modes of analysis like

Elastic,Elastoplastic,Meshing,Limit Analysis,Mohr-Coulumb,Strength Reduction.

Optum allows easy modelling with automatically recognising intersections,surfaces

etc.Geometrical data along with coordinates may be added with a click of mouse.Autocad files

can be easily imported to the Optum software using DXF file format.Optum Includes various

Laboratory tests Standard/Procedures

Specific gravity IS: 2720 (Part 3) 1980

Grain size analysis IS: 2720 ( Part 4) 1985

Atterberg limit test IS: 2720 ( Part 5) 1985

Differential free swell index IS: 2720 ( Part 40) 1977

Standard Proctor compaction test IS: 2720 ( Part 7) 1980

Swelling Pressure IS: 2720 ( Part 41) 1977

Unconfined compressive strength test IS: 2720 (Part 10) 1991

Unconsolidated Undrained Triaxial Test IS 2720 (Part11) -1993

cases with type of materials having predefined properties like Stifness,Unit weight,Angle of

friction etc.

This Software was used to plot load settlement curve and determine max Stress for footing

constructed on Virgin Black Cotton soil and for optimum Soil mix Proportion(6% molasses).To

get the desired analysis few Geotechnical shear strength parameters were calculated using

unconsoildated Undrained triaxial test .

3.3 Materials used in experimental work:

3.3.1 Black cotton soil: Specimen was collected from Kolhapur district, Maharashtra and

top layer was removed with help of shovel up to depth of 0.5m.The geotechnical properties of

black cotton soil are determined by conducting series of test on soil specimen as shown in table

1.Standard proctor tests were also performed on the virgin soil as well as soil mixes in different

proportions of molasses % by weight of soil (2, 3, 4, 6, 8, 10) to determine OMC and MDD.

Table 3.2:Properties of Black Cotton Soil

Properties Value

Specific Gravity 2.8

Liquid Limit (%) 57.0

Plastic limit (%) 31.5

Plasticity index (%) 26.5

Differential Free Swell (%) 35.0

Maximum dry density ( kN/m3) 16.1

Unconfined compression strength, (kN/m2) 176.3 KN/m2

3.3.2 MOLASSES: It is black syrupy liquid obtained as by product from sugar industry. It

contains various minerals and vitamins most of it is sugar only. The type of molasses used for the

study is cane molasses. Various physical and chemical properties collected from the factory are

given in table 2 below. The molasses was collected from Budhewal sugar mill, Ludhiana.

Disposal of molasses is of great concern as it increases the PH value of land and makes it unfit

for agriculture purposes. India is the 2nd

largest producer of sugar and in the process of sugar

extraction from sugarcane; molasses is produced in huge amount.

Out of every 100tons of sugar cane crushed 4.5 tons of molasses is left as by product.

Table 3.3: Chemical Composition of Molasses

Sr.No. Chemical Composition Molasses

1. Dry matter 73%

2. Crude protein 4.4

3. Sugars 45%

4. Fiber Nil

5. Ash 12%

6. SiO2 0.5%

7. K2O 3.5%

8. H2O 6.5%

Source: Budehwal sugar mill,Ludhiana

Table 3.4: Physical Properties of Molasses

S.No. Physical Properties Molasses

1. Colour Dark Brown

2. Specific gravity 1.4

3. Viscosity(cp at 200C) 1500

4. PH 4.5

5. Litres/tonne 714

6. Appearance Syrupy liquid

7. Gallons/tonne 157

Source: Budehwal sugar mill,Ludhiana

Water:

According to IS- Code, water to be used for Mixing and Curing should be free from injurious or

deleterious materials and fit for drinking purposes. Portable water is generally considered

satisfactory. In the present investigation, tap water was used for both mixing and curing purposes.

CHAPTER 4

4.1 RESULT AND DISCUSSION

This chapter deals with discussion on results obtained from various tests conducted on soil and its

mix. Results discussed are based on the lab experiments, observations recorded during research

work. Efforts have been made to rectify observation at every level of the study.

Atterberg Limit Test: Liquid limit of specimen soil was 57% and plastic limit 31.5. According

to Unified Soil Classification System (USCS), soil was found to be of highly compressible

nature (CH).

4.2 XRD Test: XRD is fast analytical technique used for identification of crstalline minerals.

X-ray diffraction was performed on selected thin specimen to know chemical composition of the

BC soil and detect presence of montmorillonite mineral which is considered to be the measure

cause of expansive behavior of BC soil. Anode material used was Cu on specimen of length

10mm.The start position of 2 angle was chosen to be 10 and end position as 80degrees.XRD

shows peaks value of compounds present in the soil sample in form of plot between Intenstiy on

yaxis and 2 on x axis.

2 is the angle at which X-ray beam is bombarded from Copper anode on soil sample(2gm),the

interference between Xray and crystalline sample gives list of compounds along with empirical

formula present in the sample.All results are displayed on the the monitor attached with the XRD

machine in a similar way presented below.

Fig .4.2 XRD TEST of Virgin Soil Specimen

Visible Ref. Code Compound

Name

Chemical

Formula

Semi

Quant [%]

* 00-012-

0204

Montmori

llonite

Nax ( Al ,

Mg )2 Si4

O10 ( O H

)2 z H2 O

-

Position [2Theta] (Copper (Cu))

20 30 40 50 60 70 80

Counts

0

500

1000

Montmorillonite

Montmorillonite

Montmorillonite

Montmorillonite

Montmorillonite

Black Cotton

Discussion of XRD Test

The plot between intensity and 2theta shows presence of MONTMORILLONITE mineral

at various angles along with their peaks (Figure 4.2).

4.2.1 MORPHOLOGY: It is branch of science associated with the structural and formational

study of living & non-living things.SEM instrument was used to get the micrographs of the oven-

dried sample of virgin soil & soil mixed 6% molasses.

SEM (Scanning Electron Microscope) test determines the surface morphology of sample by

providing images at various magnifications and EDS is a software which determines the

percentage of various elements available on surface of the sample magnifications. When

electrons are bombarded on the gold coated soil sample ,the beam is reflected back which gives

images of structural arrangement of sample.SEM has magnification range upto 300000times the

normal image.Gold coating is done on sample to increase conductivity especially on surface to

have better imaging. Non conductive specimens have tendency when bombarded with electron

beam to accumulate electron charge which might cause scanning faults. Therefore, ultrathin gold

coating on specimen with high vacuum evaporation machine.

Figure-4.2(a) : Micrograph of untreated soil specimen at 5000 mag.

Figure-4.2(b): Micrograph of untreated soil specimen at 10000 mags.

Figure-4.2(c):Micrograph of untreated soil specimen at 100 mags.

In Micrographs of the untreated sample, the soil structure is visible as loosely packed

blocks due to which there are large void spaces and double diffused layer is wider as

shown in figure 4.2 (a) and figure 4.2(c).

Figure-4.2(d): EDS of untreated soil specimen showing elemental composition

Table 4.2(e):Atomic % of Elements present in Virgin Black Soil Sample

Element Weight% Atomic%

C K 6.79 10.35

O K 61.2 70.11

Na K 0.24 0.19

Mg K 1.44 1.08

Al K 7.77 5.27

Si K 16.76 10.94

Ca K 1.14 0.52

Fe K 4.67 1.53

Totals 100.00

The Table shows atomic %age weight of Elemental Composition of Virgin Black Soil in

which

Calcium(Ca),Oxygen(O),Sodium(Na),Magnesium(Mg),Aluminium(Al),Silica(Si),Carbon

(C), Iron(fe) are present.These elements constitute Montmorillonite mineral compound

[Nax ( Al , Mg )2 Si4 O10 ( O H )2 z H2 O] which is major cause of expansive

behaviour of Black Soil.

EDS software confirms presence of Montmorillonite mineral in the soil sample.Hence soil

is expansive Black Cotton Soil.

4.2.2Micrographs or SEM images of Black Cotton Soil + 6% molasses

Figure-4.2(e):: Micrograph of treated soil specimen at 100 mags.with 6% molasses

Molasses forms a cementing bond with clay particles as clay particles have occupied vacant

position in soil structure to form a flocculated structure.Molasses promotes ion exhange process

between molasses and clay particles of expansive soil by decreasing thickness of double diffused.

Clay particles becomes coarser in size due to molasses addition.

Angular particles of larger size than Black cotton soil clay particles are observed in SEM

after addition of molasses.

Figure-4.2(f): Micrograph of treated soil specimen at 100 mags.with 6% molasses

Figure 4.2(f): shows non clay minerals and particles like Quartz etc have not formed bond with

molasses.Non clay soil particles seems to have low degree of bonding with molasses.

4.4 Differential free swell: It is the property of expansive soil to govern the Degree of

expansiveness. On the basis of results the soil is found to be highly expansive in nature having

free swell index 35%.

4.5 Standard Proctor Test:As per the test results with increase in percentage of molasses OMC

decreses in soil molasses mix. A different trend is observed in MDD with increasing percent of

molasses MDD keeps decreasing through out the soil mix proportions..OMC rises for 2%

molasses and falls for all other ratio of Soil mix .

Property S:M0 S:M1 S:M2 S:M3 S:M4 S:M5

Proportion

Soil:

Molasses

100:0 98:2 96:4 94:6 92:8 90:10

Optimum

Moisture

Content (%)

22.5 23 16 15 12.5 12

MDD(gm/cc) 1.56 1.47 1.55 1.53 1.50 1.49

Figure 4.5 (a): MDD and %age of molasses

1.46

1.47

1.48

1.49

1.5

1.51

1.52

1.53

1.54

1.55

1.56

1.57

0 2 4 6 8 10 12

Max. D

ry D

ensi

ty(g

m/c

c)

Percentage of molasses(%)

Discussion of Proctor Test Results:

As specific gravity of molasses(1.4) is less than the Black cotton soil(2.8)

maximum dry density decreases with increasing % of molasses.

As molasses conatins water (6.5%) due to which net water content in the soil

molasses mix rises which decreases dry density of mix.

Figure 4.5 (b): MDD and Water Content(w) for BC at various proportions

1.3

1.35

1.4

1.45

1.5

1.55

1.6

0% 5% 10% 15% 20% 25% 30%

Dry

Den

sity

(gm

/cc)

Water Content(%)

100:0 %

98:2%

96:4%

94:6%

92:8%

4.6 Swelling Pressure Test: The swelling Pressure of soil was found to be 4 kg/cm2.

The test

procedure followed for the specified test is as per IS: 2720 ( Part 41) 1977.With addition of

molasses the swelling pressure of Black cotton soil reduced considerably. The reduction in

swelling pressure is due to increased silt and sand content and less clay content. This is due to the

flocculated soil particles due to the cation exchange process between the cations of molasses and

easily exchangeable cation on soil surface. Molasses has tendency to enhance flocculation and

stability of soil aggregate as it has adhesive properties due to presence of hydroxyl group (OH)

which is mainly responsible for properties of sugar and molasses. Hydrogen bonds are

intermolecular in nature and have net positive charge on them which makes the molasses

adhesive in nature and binds the soil particles together thereby increasing the stability of

expansive clay as clay particles are negatively charged.

Table 4.6: Swelling pressure at various molasses %age

Property S:M0 S:M1 S:M2 S:M3 S:M4 S:M5

Proportion

Soil: Molasses

100:0 98:2 96:4 94:6 92:8 90:10

Swelling

Pressure

( kg/cm2)

4 2.57 1.484 0.21 0. 4 0.45

Swell pressure

reduced (%)

---- 35.75 62.9 95 90 88.75

Figure 4.6(a): % Reduction in Swelling pressure at various molasses %age

Figure 4.6 (b): Effect of molasses on swelling pressure of clay

0

20

40

60

80

100

120

Virgin Soil Soil+2%

Molasses

Soil+4%

Molasses

Soil+6%

Molasses

Soil+8%

Molasses

Soil+10%

Molasses

% R

edu

ctio

n i

n S

wel

lin

g

Virgin Soil

Stabilised Soil

4

2.57

1.484

0.50.21

0.45

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 2 4 6 8 10 12

Swel

ling

Pre

ssu

re(k

g/c

m2

)

Molasses(%)

4.6.2 Discussion of Swelling pressure results:

With increasing %age of molasses up to 8% swelling pressure shows decline but any

percentage greater than that reduces the ability of molasses to stabilize the Black Cotton

soil. With increasing value of molasses above 8% value of swelling pressure starts

increasing again.

Molasses reduces the amount of montmorillonote mineral either by breaking it into its

constituent elements or by making a more stable less expansive compound with

montmoriilonite mineral.It is predicted by XRD Test as shown below figure 4.(c).Only

one peak of low intensity is left after addition of molasses.

Figure 4.6 (c): Montmorrilonite mineral at 6%molasses + Black Cotton Soil

Position [2Theta] (Copper (Cu))

10 20 30 40 50

Counts

0

2000

4000

6000

Black Cotton low angle

m

o

n

t

m

o

r

r

i

l

o

n

i

r

e

4.7 Unconfined Compressive Strength Test: The test procedure followed was as per Indian

standard code IS 2720 (Part 10): 1991.The table shown below shows the compressive stress

induced in soil specimen at different strain values. The Unconfined Compressive Strength test is

special form of triaxial test in which confining pressure is zero and the sample is loaded axially.

The test is designed basically for clayey soil with mounted load proving ring and a strain

measuring dial gauge attached to the apparatus .The prerpared mould has dimensions equal to

38mm in diameter and 78mm length wise. Load proving readings and area were measured at

every strain value in multiples of 50.

CALCULATIONS AND PLOTTING:

a) The axial strain, e, shall from the following relationship:

e= L/LO

where L = the change in the specimen length as read from the strain dial indicator,

b) The average cross-sectional area, A, at a particular strain shall be determined from the

following relationship:

A =- Ao / (l-e)

where Ao = the initial average cross-sectional

area of the specimen.

c) c= P/A

c = Compressive Stress

P = the compressive force, and

A = average cross-sectional area

Table 4.7(a) UCS value for virgin soil

UNCONFINED COMPRESSIVE STRENTH (FOR VIRGIN SOIL)

S/ No. Calculations

Dial gauge Proving ring Strain Corrected

area

A=A0/(1-)

( cm2)

Compressive

stress ()=P/A (kg/cm

2)

Reading Deformation

(L) Reading Load

(p) kg

=L/L0

1 0 0

0 0 0.000 19.635

0.000

2 50

0.5 10

5 0.006 19.762

0.253

3 100

1 16

8 0.013 19.890

0.402

4 150

1.5 27.5

13.75 0.019 20.020

0.687

5 200

2 41.5

20.75 0.026 20.152

1.030

6 250

2.5 47.5

23.75 0.032 20.285

1.171

7 300

3 54

27 0.038 20.420

1.322

8 350

3.5 62.5

31.25 0.045 20.557

1.520

9 400

4 67.5

33.75 0.051 20.696

1.631

10 450

4.5 72.5

36.25 0.058 20.837

1.680

12 550

5.5 77.5

38.75 0.071 21.125

1.716

13 600

6 81.5

40.75 0.077 21.271

1.763

Table 4.7(b) UCS value for virgin soil +2%molasses

mix (S:M) (2% molasses)

UNCONFINED COMPRESSIVE STRENTH

S/ No. Calculations


area

A=A0/(1-)

Compressive


2) Reading Deformation

(L) Reading Load

(p)

=L/L0

1 0 0 0 0 0.000 19.635 0.000

2 50 0.5 5 2.5 0.006 19.762 0.127

3 100 1 15 7.5 0.013 19.890 0.377

4 150 1.5 24 12 0.019 20.020 0.599

5 200 2 43 21.5 0.026 20.152 1.067

6 250 2.5 48 24 0.032 20.285 1.183

7 300 3 54 27 0.038 20.420 1.322

8 350 3.5 63 31.5 0.045 20.557 1.532

9 400 4 68 34 0.051 20.696 1.643

10 450 4.5 72.5 36.25 0.058 20.837 1.740

11 500 5 78.5 39.25 0.064 20.980 1.871

12 550 5.5 83 41.5 0.071 21.125 1.965

13 600 6 87 43.5 0.077 21.271 2.045

14 650 6.5 90 45 0.083 21.420 2.101

Table 4.7(c) UCS value for virgin soil +4%molasses



S/ No. Calculations


area

A=A0/(1-)

Compressive


2) Reading Deformation

(L) Reading Load

(p)

=L/L0

1 0 0 0 0 0.000 19.635 0.000

2 50 0.5 8.75 4.375 0.006 19.762 0.221

3 100 1 18.75 9.375 0.013 19.890 0.471

4 150 1.5 25 12.5 0.019 20.020 0.624

5 200 2 50 25 0.026 20.152 1.241

6 250 2.5 61.25 30.625 0.032 20.285 1.510

7 300 3 75 37.5 0.038 20.420 1.836

8 350 3.5 82.5 41.25 0.045 20.557 2.007

9 400 4 91.25 45.625 0.051 20.696 2.205

10 450 4.5 97.5 48.75 0.058 20.837 2.340

11 500 5 102.5 51.25 0.064 20.980 2.443

12 550 5.5 106.25 53.125 0.071 21.125 2.515

13 600 6 108.75 54.375 0.077 21.271 2.556

14 650 6.5 115 57.5 0.083 21.420 2.684

Table 4.7(d) UCS value for virgin soil +6%molasses



S/

No.

Calculations


area

A=A0/(1-)

Compressive

stress

()=P/A

(kg/cm2)

Reading Deformation

(L)

Reading Load

(p)

=L/L0

1 0 0 0 0 0.000 19.635 0.000

2 50 0.5 9.5 4.75 0.006 19.762 0.240

3 100 1 22.5 11.25 0.013 19.890 0.566

4 150 1.5 35 17.5 0.019 20.020 0.874

5 200 2 45 22.5 0.026 20.152 1.315

6 250 2.5 60 30 0.032 20.285 1.541

7 300 3 75 37.5 0.038 20.420 1.861

8 350 3.5 85 42.5 0.045 20.557 2.067

9 400 4 95 47.5 0.051 20.696 2.295

10 450 4.5 110 55 0.058 20.837 2.640

11 500 5 120 60 0.064 20.980 2.860

12 550 5.5 125 62.5 0.071 21.125 2.959

13 600 6 127.5 63.75 0.077 21.271 2.997

14 650 6.5 129 64.5 0.083 21.420 3.011

Table 4.7(e) UCS value for virgin soil +8%molasses



S/

No.

Calculations


area

A=A0/(1-)

Compressive

stress

()=P/A (kg/cm

2)

Reading Deformation

(L) Reading Load

(p)

=L/L0

1 0 0 0 0 0.000 19.635 0.000

2 50 0.5 9 4.5 0.006 19.762 0.228

3 100 1 20 10 0.013 19.890 0.503

4 150 1.5 32.5 16.25 0.019 20.020 0.812

5 200 2 52.25 26.125 0.026 20.152 1.296

6 250 2.5 62 31 0.032 20.285 1.528

7 300 3 76 38 0.038 20.420 1.861

8 350 3.5 84.5 42.25 0.045 20.557 2.055

9 400 4 92 46 0.051 20.696 2.223

10 450 4.5 100 50 0.058 20.837 2.400

11 500 5 104.5 52.25 0.064 20.980 2.490

12 550 5.5 110.5 55.25 0.071 21.125 2.615

13 600 6 116.25 58.125 0.077 21.271 2.733

14 650 6.5 120 60 0.083 21.420 2.801



S/

No.

Calculations


area

A=A0/(1-)

Compressive

stress

()=P/A (kg/cm

2)

Reading Deformation

(L) Reading Load

(p)

=L/L0

1 0 0 0 0 0.000 19.635 0.000

2 50 0.5 7.5 3.75 0.006 19.762 0.190

3 100 1 17 8.5 0.013 19.890 0.427

4 150 1.5 26 13 0.019 20.020 0.649

5 200 2 45.5 22.75 0.026 20.152 1.129

6 250 2.5 55 27.5 0.032 20.285 1.356

7 300 3 65.5 32.75 0.038 20.420 1.604

8 350 3.5 75 37.5 0.045 20.557 1.824

9 400 4 82.5 41.25 0.051 20.696 1.993

10 450 4.5 90 45 0.058 20.837 2.160

11 500 5 100 50 0.064 20.980 2.383

12 550 5.5 104.5 52.25 0.071 21.125 2.473

13 600 6 107 53.5 0.077 21.271 2.515

14 650 6.5 110 55 0.083 21.420 2.568

Table 4.7(f) UCS value for virgin soil +10%molasses

Figure 4.7(a) Stress Strain Curve for Soil-Molasses mix for all proportions

0

0.5

1

1.5

2

2.5

3

3.5

0 0.02 0.04 0.06 0.08 0.1

Stress

(Kg/cm2)

Strain

10% molasses

8% molasses

6% molasses

4% molasses

2% molasses

virgin soil

Figure 4.7(b) UCS value & %ages of molasses added to Black Soil

4.7.2 Discussion of UCS Test Results:

With increase in percentage of molasses maximum dry density decreased but UCS value

increased.It may be due to Molasses acts as a adhesive having net positive charge on its

constituting Hydroxyl group (OH) which helps form a better bond with negative charged clay

particles. Molasses also decreases thickness of double diffused layer which allows the clayey

particles to exchange ions and flocculate easily which is also the cause of increased UCS value

due to molasses addition.

Maximum value of UCS was observed at 6% molasses mix with soil specimen.molasses

increased the cohesion value of soil therby increasing UCS strength of soil.Up to 6% additon of

1.763

2.101

2.684

3.011

2.801

2.589

0

0.5

1

1.5

2

2.5

3

3.5

0 2 4 6 8 10 12

UC

S V

alu

e (K

g/c

m2)

Molasses Percentage(%)

molasses specimen showed increase in strength which started decline there after.At 8 % soil-

molasses mix a value slightly lesser than maximum UCS value was observed but after that

decline was considerable.

As clearly visible from the results of Unconfined Compressive test Results that molasses alone is

capable of reducing swell pressure and increasing strength up to 70%.While conducting the UCS

test no curing was done as molasses is soluble in water.UCS prepared sample for virgin as well as

molasses mix specimen were casted in mould and tested for UCS strength immediately. Molasses

reduces the pH of soil which is indication of cation exchange process started at the surface, pH

reduction is also indication that soil changed from neutral to slightly acidic..

4.8 OPTUM-G2 ANALYSIS: Unconsolidated undrained Triaxial test performed on virgin soil

at different confining pressures 1kg/cm2

,2kg/cm2 and 3kg/cm

2 for 3 samples helped in finding

out geotechnical engineering parameters(E,c, , ).These parameters when used in Optum G2

gave load settlement curve,point of max stress and value of max stress for black cotton soil.

In the analysis of footing on black cotton soil settlement assumed was along y axis maintaing the

case of standard fixities on x axis.No Water table was assumed below the ground level.The

analysis type used was multiplier elastoplastic where load is increased on soil mass until it fails.

Figure 4.8 (a)Mohr Circle for Black Cotton soil Obtained from Triaxial test

Figure 4.8 (b)Mohr Circle for Black Cotton + 6% molasses soil Obtained from Triaxial test

Soil:Molasses E(MPa) C(kn/m2) (degree) (poissons

ratio)

Dry density(Yd )

Kn/m3

Ko

(100:0)% 4 10.3 12.52 0.33 15.6 0.8

(94:6)% 6 13.69 20.10 0.4 15.3 0.8

Table 4.8.1 Inputs used for Numerical Modelling

Numerical Modelling in Optum G2-Modelling is to stimulate a square foundation 2m x 2m

constructed on Black cotton soil of high compressibility.The foundation was subjected to

multiplying load in ve y axis with initial value of 1kn/m2.The Load Displacement analysis is

based on mohr-coloumb soil model and interface is assumed as Noassociated between Black

cotton soil and foundation.The non associated interface ensures whole stress has been transferred

from foundation to soil particles. Elemental mesh consists of triangular element each with 6

nodes.Water table has been assumed at 1.25m below the footing.

The analysis was based on mechanical and physical geoengineering parameters like

cohesion(c),Poissions ratio(),Friction angle(),Youngs modulus(E) obtained from Triaxial

UU test to approach closely a actual state.It is assumed that soil base will have elastoplastic

behaviour under increament of loads with different values of stress for varying deformations.

Figure 4.8(c) Cross sectional view of Numerical Model

Figure 4.8 (d)Comparison of Stress-Displacemnt curve Obtained from Optum G2

-700.000

-600.000

-500.000

-400.000

-300.000

-200.000

-100.000

0.000

-0.400-0.350-0.300-0.250-0.200-0.150-0.100-0.0500.000

Str

ess

(K

n/m

2)

Displacement (m)

Virgin soil

Black Soil + 6% Molasses

4.8.1 Discussion of Optum G2 Test Results

From Stress Displacement curve figure4.8(d) it was observed that the load bearing

capacity increases from 256 Kpa to 570Kpa when Black soil was mixed with

6%molasses as compared to virgin Black soil.

Incresed Failure stress value for the optimum mix(6% molasses) is due to increase in

friction & bonding between particles of stabilised soil.Particles increase in size due to

addition of molasses and it reduces overall voids in the soil.

With increase in percentage of molasses maximum dry density decreased but UCS value

increased.It may be due to Molasses acts as a adhesive having net positive charge on its

constituting Hydroxyl group (OH) which helps form a better bond with negative charged

clay particles. Molasses also decreases thickness of double diffused layer which allows

the clayey particles to exchange ions and flocculate easily which is also the cause of

increased UCS value due to molasses addition.

CHAPTER 5

CONCLUSION

5.1 Following conclusions are obtained from the study

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