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OMUTOKO JULIAN OTANGA |

F16/36598/2010 Page | 1

UNIVERSITY OF NAIROBI

Mechanical Improvement of Highly Plastic and Expansive Soils for

Low Volume Sealed Roads Using Fired Clay: A Case of Syokimau-

Katani Area

Presented by: Omutoko Julian Otanga, F16/36598/2010

Supervisor: Eng. (Dr.) S. Osano

A project submitted as partial fulfillment for the requirement for the

award of the degree of

BACHELOR OF SCIENCE IN CIVIL ENGINEERING

2015


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DECLARATION

I, Omutoko Julian Otanga, do declare that this report is my original work and to the

best of my knowledge, it has not been submitted for any degree award in any

University or Institution.

Signed: ________________________ Date_________________________

Omutoko Julian Otanga

F16/36598/2010

CERTIFICATION

I have read this report and approve it for examination

Signed: _________________________ Date_________________________

Eng. (Dr.) S. Osano


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DEDICATION

The works in this project are dedicated to my father Wycliffe Omutoko, my mother

Lillian Omutoko and my brother Ian Omutoko. All have played a great role in

ensuring that I have gotten this far through their endless support, encouragement

and sacrifices they have made for me.

Academicians in the engineering field who have walked this path before me cannot

be downplayed as this is a build-up of work they have done previously.


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ACKNOWLEDGEMENT

I would like to give thanks to the Almighty God for grace, strength and focus

accorded to me and my parents for the immense material and emotional support.

Engineering professionals I have interacted with during my study period for the

Bachelor of Science Degree: I appreciate the training, experience and wide

knowledge I have gained during my student attaché opportunities under your

wings.

I also appreciate the University of Nairobi staff for all the support through my

study period in the university and have made this a reality.

Asanteni Sana! (Thank You)


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Table of Contents 1. Introduction ............................................................................................................................. 7

1.1 Project Description ........................................................................................................... 8

1.2 Problem Statement ........................................................................................................... 8

1.3 Objectives ......................................................................................................................... 8

1.3.1 Main Objective.......................................................................................................... 8

1.3.2 Specific Objectives ................................................................................................... 8

1.4 Scope of study .................................................................................................................. 9

2. Literature Review .................................................................................................................. 10

2.1 Background Information ................................................................................................ 10

2.2 Formation of Expansive Soils ........................................................................................ 10

2.3 Current Practice Methods ............................................................................................... 10

2.3.1 Excavation and Replacement .................................................................................. 10

2.3.2 Pre-wetting the soil ................................................................................................. 11

2.3.3 Preventing access of water to the soil ..................................................................... 11

2.3.4 Application of surcharge pressure .......................................................................... 12

2.3.5 Stabilization by chemical admixtures ..................................................................... 12

2.4 Characteristics of Expansive Clays ................................................................................ 13

2.4.1 Problems associated with expansive clays .............................................................. 13

2.4.2 Clay mineralogy ...................................................................................................... 16

2.5 Proposed Solution .......................................................................................................... 17

2.6 Preferred Attributes ........................................................................................................ 17

3. Methodology .......................................................................................................................... 19

3.1 Introduction .................................................................................................................... 19

3.2 Sampling......................................................................................................................... 21

3.3 Materials Testing ............................................................................................................ 26

3.3.1 Atterberg Limits ...................................................................................................... 26

3.3.2 Linear Shrinkage ..................................................................................................... 29

3.3.3 Compaction Related Tests ...................................................................................... 30

4. Results and Analysis .............................................................................................................. 36

4.1 Classification Tests ........................................................................................................ 36


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4.1.1 Particle Size Distribution ........................................................................................ 36

4.1.3 Plastic, Liquid Limit and Plasticity Index Variation .............................................. 38

4.2 Linear Shrinkage ............................................................................................................ 39

4.3 Compaction Related Tests .............................................................................................. 41

4.3.1 Maximum Dry Density and Optimum Moisture Content ....................................... 41

4.3.2 MDD and OMC Variation From Neat to 40% Blend ............................................. 43

4.4 California Bearing Ratio ................................................................................................ 44

4.4.1 CBR Theory 1 ......................................................................................................... 44

4.4.2 CBR Theory 2 ......................................................................................................... 46

4.5 Test Summary ................................................................................................................ 46

4.6 Cost Analysis.................................................................................................................. 48

5. Project Constraints ................................................................................................................. 49

5.1 Storage of Material ......................................................................................................... 49

5.2 Equipment Unavailability .............................................................................................. 49

5.3 Faulty Laboratory Equipment ........................................................................................ 49

6. Recommendations and Conclusion ....................................................................................... 51

6.1 Recommendations .......................................................................................................... 51

6.2 Conclusion ...................................................................................................................... 51

7. References ............................................................................................................................. 52

8. Appendices ............................................................................................................................ 53

8.1 Particle Size Distribution ............................................................................................... 53

8.2 Plastic Limit, Liquid Limit and Plasticity Index ............................................................ 53

8.2.1 Neat ......................................................................................................................... 53

8.2.2 20% Blend ............................................................................................................... 54

8.2.3 40% Blend ............................................................................................................... 54

8.3 Maximum Dry Density and Optimum Moisture Content .............................................. 55

8.3.1 Neat ......................................................................................................................... 55

8.3.2 20% Blend ............................................................................................................... 56

8.3.3 40% Blend ............................................................................................................... 57


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TABLE OF FIGURES

FIGURE 1: PREVENTING WATER ACCESS TO THE SOIL ................................................................................. 12

FIGURE 2: SWELLING & CRACKING DURING WET & DRY SEASONS DAMAGING THE FOUNDATION.......... 14

FIGURE 3 CRACKING OF A PAVEMENT ........................................................................................................ 15

FIGURE 4.1 FLOOR SLAB CRACKING ........................................................................................................... 15

FIGURE 5 FLOOR SLAB CRACKING .............................................................................................................. 15

FIGURE 6 WALL UNDER DISTRESS .............................................................................................................. 16

FIGURE 7 DIFFERENTIAL SETTLEMENT CAUSING CRACKING IN WALLS ..................................................... 16

FIGURE 8: EXCAVATED SITE IN SYOKIMAU ................................................................................................ 21

FIGURE 9: EXCAVATED SITE SHOWING ROCK PROFILE .............................................................................. 21

FIGURE 10: SHOWING EXTENT OF BLACK COTTON SOIL ........................................................................... 22

FIGURE 11: MEASUREMENT OF BLACK COTTON SOIL EXTENT .................................................................. 22

FIGURE 12: BORROW PIT 1 USED FOR SAMPLING ........................................................................................ 22

FIGURE 13: BORROW PIT 2 USED FOR SAMPLING ........................................................................................ 23

FIGURE 14: THE KILN USED FOR FIRING THE CLAY ..................................................................................... 24

FIGURE 15: THE KILN IN THE PROCESS OF FIRING THE CLAY FROM 300 TO 450 DEGREES CELSIUS ............ 24

FIGURE 16: FIRED CLAY BEING REMOVED AFTER FIRING ........................................................................... 24

FIGURE 17: COARSE PARTICLES-DIDN’T DISINTEGRATE AFTER FIRING ..................................................... 25

FIGURE 18: FINE PARTICLES AFTER FIRING ................................................................................................. 25

FIGURE 19 : LIQUID LIMIT APPARATUS ...................................................................................................... 27

FIGURE 20: PLASTIC LIMIT APPARATUS ..................................................................................................... 29

FIGURE 21: LINEAR SHRINKAGE APPARATUS ............................................................................................. 30

FIGURE 22: CBR TEST APPARATUS ............................................................................................................ 32

FIGURE 23: IN-SITU CBR PENETRATING MACHINE .................................................................................... 33

FIGURE 24: MDD APPARATUS-LIGHT AND HEAVY COMPACTION ............................................................. 35

List of Tables

TABLE 1: IMPROVED SUBGRADE CLASSES- KRDM-III .................................................................. 18

TABLE 2: SOIL PROPERTIES SUMMARY .......................................................................................... 46

TABLE 3: IMPROVED SUBGRADE CLASSES ..................................................................................... 47

TABLE 4: PARTICLE SIZE DISTRIBUTION- SAMPLE 1 ..................................................................... 53

TABLE 5: LIQUID LIMIT, PI AND PL- NEAT SAMPLE ...................................................................... 53

TABLE 6:LIQUID LIMIT, PI AND PL- 20% BLEND .......................................................................... 54

TABLE 7: LIQUID LIMIT, PI AND PL- 40% BLEND .......................................................................... 55

TABLE 8: MDD AND OMC DATA SHEET- NEAT SAMPLE .............................................................. 55

TABLE 9: MDD AND OMC DATA SHEET- 20% BLEND .................................................................. 56

TABLE 10: MDD AND OMC DATA SHEET- 40% BLEND ................................................................ 57


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1. Introduction

1.1 Project Description

This is an Experimental Research Project aimed at finding a means to making use of

locally available materials at the least available cost. The research project leans towards

the mechanical and chemical stabilization of highly plastic soils which have proved to be

quite a nuisance to the civil engineering practice over the years. This has also been of

critical importance especially in urban areas where haulage distances to dumping sites

and material borrow pits are long thus making the project expensive and logistically

challenging.

1.2 Problem Statement

The soil profile in Kenya is very variable and this poses a challenge of many changes in

the design of a particular project. Expansive soils are difficult to deal with and in many

of the cases results in high escalations in the project cost. This is attributed to

replacement (cut-to-spoil) of the expansive soils with more suitable materials that are

capable of sustaining the imposed loads, be it a road construction project or a building.

Many researchers have attempted to come up with varied solutions for this menace and

this project is also aimed at finding a long-lasting, effective and feasible solution.

1.3 Objectives

1.3.1 Main Objective

To assess the feasibility of stabilizing expansive and plastic clays without use of

borrowed/foreign material

1.3.2 Specific Objectives

To determine the optimum mix proportions of fired clays to untreated

materials for use in road construction

To determine the economic viability of this treatment method in comparison

with existing techniques

To establish the change in engineering properties of the soil after such

stabilization


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To determine if the swell of the expansive soils can be mitigated through the

use of the fired clays as a mechanical stabilizer

1.4 Scope of study

The research will be limited to the engineering properties of soils such as classification

tests according to the Kenya Road Design Manual-Part III i.e. plasticity indices, particle

size distribution, shrinkage limits, bearing ratios. The short term economic implications

will also be assessed. Durability, deflections and deformation may not be looked into due

to the long term nature of these kinds of tests and are constrained by the time and

resources allowed for this project.


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2. Literature Review

2.1 Background Information

The road construction industry is face by a myriad of challenges when it comes to the

properties of soils for engineering purposes. These include high plasticity soils,

expansive soils, and low bearing capacities just to name a few. For a project to be

feasible and attain its objective of moving goods and people from one point to the other

safely and efficiently; it is necessary for optimum conditions to be met. For road

construction, this is highly dependent of the engineering properties of the soil within the

proposed corridor.

In this case, the expansiveness and high plasticity components of a soil will be looked

into. It will be with an aim to mitigating or coming up with a best practice method to

reduce construction cost without reducing the quality of desired sub-grade material.

2.2 Formation of Expansive Soils

Black cotton soils have been identified on igneous, sedimentary and metamorphic rocks.

They are formed mainly by the chemical weathering of mafic (basic) igneous rocks such

as basalt, norite, andesites, diabases, dolerites, gabbros and volcanic rocks and their

metamorphic derivatives (e.g. gneisses) which are made up calcium rich feldspars and

dark minerals which are high in the weathering order, in poorly drained areas with well

defined wet and dry seasons. All constituents weather to form amorphous hydrous oxides

and under suitable conditions clay minerals develop. The absence of quartz leads to the

formation of fine grained, mostly clay size, plastic soils which are highly impermeable

and easily becomes waterlogged. In addition abundant magnesium and calcium present

in the rock adds to the possibility of formation of black cotton soil with its attendant

swelling problem (Ola, 1983). The black cotton soils have also formed over sedimentary

materials such as shales, limestones, slates among others.

2.3 Current Practice Methods

2.3.1 Excavation and Replacement

In reference to the current Road Design Manual, Kenya- Part III (1990) recommends

cutting to spoil of materials with a CBR ratio less than 2; and for those with CBR


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between 2 and 30 require improvement through stabilization techniques (mechanical

or chemical) and/or complete excavation and replacement with suitable material.

The unsuitable soils is excavated to such a depth that effects of the loading are of not

much significance, relying on the knowledge that loading effects are only significant

to a certain depth below the ground surface.

The material being put back should not cause problems with respect to the in situ

material (D.R. Snethen, 1979). For example, granular soils should never be used as

backfill for sub-excavation and replacement projects. The use of granular materials

encourages collection of water at the surface of the underlying in situ materials.

Backfill materials should be impermeable and preferably non-swelling (silts, clayey

silts, silty clays, or some clays). Backfill material, particularly remolded in situ soil,

should be replaced and compacted with careful moisture and density control

(AASHTO T-99).

2.3.2 Pre-wetting the soil

The objective of pre-wetting is to allow desiccated swelling soils to reach equilibrium

prior to placement of the roadway or structure. The most commonly applied method

for accelerating swelling by this technique is ponding (D.R. Snethen, 1975).

Das (1984) indicates that that submerging the swelling soil in water achieves most of

the expected heave before construction. However this technique may be time

consuming because of water seepage through highly plastic soil. Hauck (1959), and

Gromko (1974) propose a 10 to 15 cm thick layer of coarse gravel, sand or granular

soil on top of the area will aid considerably in providing a good working surface

during and after prewetting. This layer has advantages in reducing evaporation,

providing a minor surcharge, as well as making a level uniform subgrade. Prewetting

technique of expansive soil may be suitable for single family homes. Also, the top

wetted soil may be mixed with lime and compacted to reduce soil’s plasticity and

increasing soil’s load bearing capacity as well (Kalantari, 1991).

2.3.3 Preventing access of water to the soil

Since a change in moisture content is the main factor influencing the volume change

of swelling soils, it is obvious that if the soil could be isolated from any moisture

changes, volume change could be reduced or minimized. In this context, waterproof


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membranes could be used as a way of limiting access of water and minimizing

moisture changes. (Snethen, 1975).

Figure 1: Preventing water access to the soil

One of the more common methods of keeping constant moisture and/ or preventing

water access is through the installation of impermeable barriers (such as retaining

walls and geotextile membrane) and adequate drainage systems and control of

vegetation coverage (Gromko, 1974; O’Neill and Poormoayed, 1980).

2.3.4 Application of surcharge pressure

Loading the expansive soil with pressure greater than the swelling pressure is a

method by which swelling can be prevented. However, pavement loads are generally

insufficient to prevent expansion, and this method is usually applied in the case of

large buildings or structures imposing high loads (Sallberg, 1965). The use of this

method is limited to swelling soils with low expansive pressures, and a Careful

balancing of swell pressures and pavement weights is required.

2.3.5 Stabilization by chemical admixtures

Soil stabilization is the process done to a soil to maintain, alter or improve the

performance of the soil.

Chemical stabilization has been used as a method for altering the clay structure or

clay-water combination to prevent or minimize swelling of expansive clays.

Cementation by lime, lime-fly ash, and cement has been used. Ion exchange (addition

of divalent and trivalent salts), cation fixation in expanding lattice clays (with


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potassium), deactivation of sulfates (with calcium chloride), waterproofing (silicones,

asphalts), cementation (silicates, carbonates, lignins; phosphoric acid), and alteration

in permeability and wetting properties (surface active agents,wetting agents) have all

been attempted or used to reduce the expansive properties of swelling clays.

However, due to mixing problems, economics, effectiveness, and practicability, none

of these are recommended for large scale routine treatment of swelling soils.

2.4 Characteristics of Expansive Clays

The black cotton soil is known as an expansive type of soil which expands suddenly

and starts swelling when it comes in contact with moisture, it also shrinks upon

drying. Due to this, its strength and other engineering properties are very poor.

2.4.1 Problems associated with expansive clays

2.4.1.1 High swelling pressures

Such type of large scale distress, due to expansive shrinking nature of expansive soil,

can be prevented by either obstructing the soil movement and reducing the swelling

pressure of soil or making the structure sufficiently resistant to damage from soil

movement which may end up being very expensive compared to other by-passive

methods.

2.4.1.2 Foundation Damage

Damage to home supported on shallow piers. As shown in Figure 2:

(1) At the beginning of the rainy season, the piers are still supported by friction with

the soil. When it begins to rain, water enters deep into the soil through the cracks.

(2) After 5 to 10 large storms, the soil swells, lifting the house and piers.

(3) In the dry season, the groundwater table falls and the soil dries and contracts. As

tension cracks grow around the pier, the skin friction is reduced and the effective

stress of the soil increases (due to drying). When the building load exceeds the

remaining skin friction, or the effective stress of the soil increases to an all-time high,

adhesion is broken by this straining, and the pier sinks.


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Figure 2: Swelling & Cracking during Wet & Dry Seasons Damaging the foundation

2.4.1.3 Buckling of Pavements

These types of damages usually occur in roads or highways upper layers. This

problem is caused by swelling potential of the subsoil system (subgrade, subbase, and

base). Figure 1 shows possible deformations of pavement due to swelling of subsoil.


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Figure 3 Cracking of a pavement

2.4.1.4 Floor slab on grade cracking;

These types of damages are sequential and generally results in a hogging type of

deformation (Fig. 2).

Figure 4 Floor Slab Cracking

Figure 5 Floor Slab Cracking


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Figure 6 Wall under Distress

2.4.1.5 Differential movement

This leads to cracking of basement walls and building walls laterally and vertically

Figure 7 Differential Settlement causing cracking in walls

2.4.2 Clay mineralogy

Chemistry:

%

SiO2 51.14

Al2O3 19.76

Fe2O3 0.83

MgO 3.22

CaO 1.62

Na2O 0.11

K2O 0.04

H2O+ 7.99

H2O¡ 14.81

Total 99.52

Montmorillon, France; corresponds to (Ca0:14Na0:02)§=0:16(Al1:68Mg0:36Fe0:04)§=2:08

(Si3:90Al0:10)§=4:00O10(OH)2 ² 1:02H2O:

(Source: Dana E.S., 1892)


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2.5 Proposed Solution

Through the use of existing theories in Soil Mechanics, researchers’ publications, laboratory

tests and experimental techniques; it is hoped that a viable and feasible solution will be

achieved. This will be done through use of fired clays (chemical stabilization) and mixing

this with appropriate proportions of existing/ in-situ materials to try and achieve a

homogeneous mix of material that may be suitable for construction projects in terms of

strength, economy, durability and reliability. Firing of the clay is meant to change the

mineralogical and physical properties.

2.6 Preferred Attributes

The Road Design Manual, Part III categorizes soils with reference to their bearing

capacity as follows:

Soil Class CBR

Range

Modulus, MPa (of median

value)

S1 2 15

S2 3 to 4 25

S3 5 to 7 50

S4 8 to 14 80

S5 15 to 29 125

S6 30+ >250

Materials directly supporting the pavement shall normally comply with the following:

CBR ≈ 15% at specified compaction, normally 95% of BS Heavy (AASHTO T180)


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Swell < 2% at 100% MDD (Modified Compaction) and 4 days soak

Organic matter < 3% (percentage by weight)

Thus, all situations where the natural sub-grade is S4 or less will require placement of an

improved sub-grade. The nature and arrangement of the improved sub-grade will depend on

the CBR of the natural sub-grade and the available materials but the intention is to reinforce

the natural sub-grade with improved sub-grade layers of CBR 7 and CBR 15. Their properties

are described below.

Class S1 soils (CBR 2 or less) will thus either require stabilization or removal and replacement

with better quality material.

Class S5 (CBR 15 to 29) and S6 (CBR 30 or more) soils will not require an improved subgrade.

Table 1: Improved Subgrade Classes- KRDM-III

Subgrade

Class

CBR design Density for

determination of

CBR design

(% of MDD of BS

Heavy)

Wet

Climatic

Zones

4 days

soaked

value

Dry Climatic Zones

At

OMC

4 days soaked

value

S15 Min 15 Min 15 Min 7 95

S7 7 to 14 7 to 14 3 to 14 93

The maximum PI of the improved sub-grades should be 30 and 25 for S7 and S15 respectively;

and the maximum swell should be 2.0% and 1.5% respectively.


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3. Methodology

3.1 Introduction

This involved collecting of samples, conduction of laboratory tests coupled with

theoretical analysis of the obtained data. This was then followed by a discussion of the

results obtained.

The test material was sourced from the Syokimau area of Machakos County

approximately 15 km away from the Nairobi CBD. The area was chosen due to its vast

amount of coverage by the black cotton soils.

The samples were transported to the laboratory by a vehicle. The samples were stored

and shielded from weather elements.

Experimental design was engaged in this study and deductions were made from the

obtained results. The tests were conducted for both neat material and the stabilized

material for comparison purposes.


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3.2 Proposed Project Schedule

Day Date Time Activity

Week 1

Monday 02nd Feb 2015 8-11 am Sample Preparation for

classification tests

Wednesday 04th Feb 2015 11-1 pm Sample Preparation for

soil compaction

2-4pm Classification Tests

Friday 06th Feb 2015 9am – 5pm Firing of the clay

10am- 4pm Compaction/Proctor

Tests

Week 2

Monday 09th Feb 2015 8-11 am Preparation of fired

clay

Wednesday 11th Feb 2015 11- 4pm Compaction of

stabilized material

Week 3

Monday 16th Feb 2015 8-11 am Preparation of CBR

material

Monday 23rd Feb 2015 8-1 pm Moulding CBR

samples and soaking

Friday 27th Feb 2015 10-4pm Penetration of CBR


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3.3 Sampling

A representative sample of the batch was obtained. This was done by digging five trial

test pits at different locations of the test area. The top soil was first removed and holes of

about 300mm diameter dug to a depth of 500mm. The samples were then put in a sack

and mixed thoroughly.

Figure 8: Excavated Site in Syokimau

Figure 9: Excavated Site Showing Rock Profile


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Figure 10: Showing Extent of Black Cotton Soil

Figure 11: Measurement of Black Cotton Soil Extent

Figure 12: Borrow Pit 1 used for sampling


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Figure 13: Borrow pit 2 used for sampling

A small portion was taken and put into a moisture bag for natural moisture content

testing. The sample was labelled with an indication of its locality and date of sampling.

The sample was then quartered and appropriate amounts set aside for the various

required tests

A portion was set aside to produce the fired clays and the rest was used as neat material

for conducting the tests.

For preparation of the fired clay:

1. It was first air dried for 7 days to get rid of the natural moisture content.

2. It was then spread into two trays and put into a kiln.

3. In the kiln it was first heated for 1 hour at 105⁰C in order to lose the atmospheric

water.

4. After hour 1, temperature was increased to 200⁰C

5. After hour 2, temperature was increased to 310⁰C and maintained for 2 hours. At this

stage burning of carbon and sulphur took place

6. The temperature was then increased to 450⁰C for another two hours. Burning of

sulphur and carbon also took place at this stage.

7. A target of 800⁰C was desired but this could not be achieved due to limitations of the

kiln that was available which could only reach a temperature of 500⁰C.


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Figure 14: The kiln used for firing the clay

Figure 15: The kiln in the process of firing the clay

Figure 16: Fired Clay being removed after firing


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Figure 17: Coarse Particles-Didn’t disintegrate after firing

Figure 18: Fine particles after firing


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3.4 Materials Testing

Testing for the materials obtained were done with accordance to British Standards i.e. BS

1377 and Kenya Road Design Manual Part III for fine grained soils.

Tests were conducted for both neat and stabilized material.

These included:

3.4.1 Atterberg Limits

3.4.1.1 Liquid Limit

Sample Preparation

Material retained on the 425 μm sieve was removed from the sample.

Objective

To determine the moisture content at which a soil passes from the liquid state to the

plastic state

Apparatus

1. Test sieves, of sizes 425 μm and 2 mm, with receiver.

2. Apparatus for determination of moisture content

3. A metal straight edge

4. Two palette knives

5. A flat glass plate, a convenient size being 10 mm thick and about 500 mm square.

6. A wash bottle containing distilled water

7. A stainless steel cone (as Specified in BS 1377-2 Cl. 4.3.2.4)

8. A metal cup (as Specified in BS 1377-2 Cl. 4.3.2.5)

9. A stopwatch/clock


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Figure 19 : Liquid Limit Apparatus

Procedure

The soil sample passing the 425μm sieve was taken and placed onto the glass plate.

Using the wash bottle, distilled water was evenly poured onto the sample.

The palette knives were used to create a homogeneous paste of the soil. This was a

trial and error procedure and was done so as to estimate a cone penetrometer reading

of about 15mm.

The stainless steel cup was lined with some oil to ensure no soil adheres to the sides

and the paste filled into the cup. To avoid having air pockets, the cup was tapped on a

hard surface lightly and the depression filled with more paste until an even surface

was achieved. The even surface was made possible by use of the straight edge.

The penetration cone was locked in the raised position and the supporting assembly

lowered so that the tip of the cone just touched the surface of the soil, with the cone in

its correct position (i.e. a slight movement of the cup just marking the soil surface).

The stem of the dial gauge was then lowered to contact the cone shaft.

The cone was released for a period of 5s. After locking the cone in position the stem

of the dial gauge was lowered to contact the cone shaft and the reading of the dial

gauge recorded to the nearest 0.1 mm. The difference between the beginning and end

of the drop was recorded as the cone penetration. The cone was lifted and wiped.


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The soil was then returned to the glass plate and a little more water added to it so as

to increase the cone penetration to about 16mm. The process of making a

homogeneous mix, filling the soil into the cup with no air voids and dropping the

cone penetrometer was repeated in successions of about +2mm until we had readings

of 16mm, 18mm, 20mm, 22mm and 24mm.

Samples of the wet soil at each stage were set aside for determination of moisture

content.

A linear graph of moisture content versus cone penetration was drawn and the

corresponding moisture content to a 20mm cone penetration was found to be our

liquid limit.

3.4.1.2 Plastic Limit and Plasticity Index

The plastic limit is the empirically established moisture content at which a soil

becomes too dry to be plastic. It is used together with the liquid limit to determine the

plasticity index which when plotted against the liquid limit on the plasticity chart (as

in BS 5930) provides a means of classifying cohesive soils.

Sample Preparation

It is convenient to carry out the test on a portion of the material prepared for one of

the liquid limit test. The material is meant to be passing 425μm sieve.

Objective

To determine the lowest moisture content at which the soil is plastic

Apparatus

1. Test sieves, of sizes 425 μm and 2 mm, with receiver.

2. Apparatus for determination of moisture content

3. A flat glass plate, a convenient size being 10 mm thick and about 500 mm

square.


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Figure 20: Plastic Limit Apparatus

Procedure

Approximately 20g of air-dry soil that passes 425μm sieve was put into a container

and mixed thoroughly with distilled water to form a thick uniform paste. The paste

was rolled into a ball using hands and then rolled on a glass plate using an open hand

until it attained a thread-like form of 3mm diameter. The rolled specimen was then

kneaded together and the process repeated until the thread shows signs of crumbling

at 3mm diameter. The crumbled threads were then used for moisture content

determination.

The plasticity index was obtained by getting the difference between liquid limit and

plastic limit.

3.4.2 Linear Shrinkage

Objective

To determine the linear shrinkage of the fraction of a soil sample passing a 425 μm

test sieve from linear measurements on a bar of soil.

Sample Preparation

The sample for linear shrinkage determination should be taken from sample close to

the moisture content of liquid limit.

Apparatus

1. Brass moulds,


F16/36598/2010 Page | 30

2. Oil

3. Drying oven,

4. A pair of Vernier calipers

Figure 21: Linear Shrinkage Apparatus

Procedure

The inner walls of the brass mould were cleaned and internal length measured

accurately. A thin film of oil was applied to the inner walls to prevent any soil from

adhering onto the sides. A portion of the paste prepared during determination of the

liquid limit and was close to the moisture content at the liquid limit was used.

The process of placing the soil paste into the mould was done with great care

avoiding inclusion of any air pockets. The mould was tapped lightly onto a hard

surface and leveled at the top. The specimen was allowed to dry out in the air first for

about 1hr until it detached itself from the walls of the mould. It was then transferred

into the drying oven and dried at 105˚C±5˚ c for 24hrs. The mould was then removed

from the oven and allowed to cool. The mean length of the soil bar was then

measured and recorded. For the specimens which cracked badly or broke such that the

measurements were difficult, the test was repeated.

3.4.3 Compaction Related Tests

3.4.3.1 California Bearing Ratio

This is a relationship between standard penetration of a cylindrical plunger (of a cross

sectional area=1963mm2) penetrating the red soil at a given rate of 1mm/min. At any

value of penetration, the ratio of force to the standard force is defined as the CBR.


F16/36598/2010 Page | 31

The ratio seeks to establish the strength hence the bearing capacity of the soil and

hence know how to increase its strength e.g. by stabilization (mechanical, chemical or

physical).

The force corresponding to penetration of 2.5mm and 5.0mm are computed and then

are

compared to the standard force attained by the California materials which is usually

reported as percentage.

Objective

To determine the CBR value of six samples of black cotton soil at varying dosages of

0%, 10%,20%, and 40% of fired clay.

Sample Preparation

The CBR test shall be carried out on material passing the 20 mm test sieve. If the soil

contains particles larger than this the fraction retained on the 20 mm test sieve shall

be removed and weighed before preparing the test sample. If this fraction is greater

than 25 % the test is not applicable.

The moisture content of the soil shall be chosen to represent the design conditions for

which the test results are required. Alternatively, where a range of moisture contents

is to be investigated, water shall be added to or removed from the natural soil after

disaggregation.

Apparatus

BS sieve 20mm

CBR mould (internal diameter of 152mm and internal effective height of

127mm) with detachable base plate and top plate and a collar 50mm deep

Cylindrical plunger of hardened steel and cross sectional area 1935mm2

approximately 250mm long

Machine for applying force to plunger

Three steel basins

Means of measuring penetration of plunger into the specimen

Three annular surcharge discs each having a mass of 2kg, internal diameter of

14.5mm to 150mm

Metal rammer 4.5kg with a weight of fall being 450mm

Steel straight edge (dimensions 300mm*25mm*3mm)

Spatula (blade of approximately 100mm*20mm dimensions)

Means of measuring movement of top of specimen during soaking

Weighing balance accurate 5g

Moisture tins


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Filter papers 150mm in diameter

Figure 22: CBR Test Apparatus

Procedure

1. Moulding

Moulding was done for three points i.e. 100%-62blows, 95%-25 blows, and 90% -

10blows.The mould was cleaned and weighed, then assembled on base plate and

the collar fitted on it.

A required amount of water was mixed with the sample portion thoroughly and 5

layers were compacted, each layer was compacted with 62 blows for each test

sample such that the fifth layer will end immediately at the brim of the mould

The collar was removed carefully and excess material trimmed to flush with the

top of the mould using a steel straight edge. The mould was weighed with the

base plate after removing any external material stuck on mould and base plate by

use of a brush.

The moulding procedure was repeated for the 25 and 10 blows moulding points.

2. Submersion/soaking

Soaking was done to determine the materials rate of absorption of water and

degree of swell. The perforated mould with surcharge weights was soaked for 4


F16/36598/2010 Page | 33

days (for the neat samples) and then removed from water and after removing

surcharge weights the moulds was drained for 15mins before CBR penetration

was done.

Figure 23: In-Situ CBR Penetrating Machine

CBR Penetration

Each mould was placed on CBR machine with plate in position and surcharge masses

were placed on the specimen and machine set such that the plunger is set on the

specimen.

The readings gauge was set and adjusted to prevent zero errors.

When the machine was switched on and for bearing ratio above 30% the plunger was

made to penetrate the specimen at a uniform rate of 1mm/min (at a plunger force of

250N )the readings of force were taken at intervals of penetration of 0.5m a to a total

penetration not exceeding 7.5mm

Penetration on the mould was done for both top and bottom and readings taken as

before. This was done for the three point moulds.

A graph showing force on the plunger against penetration was plotted and smooth

curve was drawn through the points. The force read from the smooth curve required

to cause a given penetration expressed as a percentage of force required to cause the

same penetration on standard curve and is defined as the CBR value of the

penetration.

The CBR value was calculated at penetrations of 2.5 and 5.0mm and the higher value

was taken.


F16/36598/2010 Page | 34

A graph was then drawn for penetrations against dry densities in mould. After

penetration the mould was removed and wet soil from the 62 blow moulds oven

dried and graded to determine the particle distribution as influenced by compaction.

3.4.3.2 Proctor Compaction Test

Objective

This test was done to determine the maximum dry density (MDD) and optimum

moisture content (OMC) of the material.

Apparatus

Cylindrical metal mould- 150mm internal diameter, effective height 115.5mm

and volume 956cm3

Detachable base plate and removable collar of approximately 50mm height

Metal rammer with a 50mm circular diameter weighing 4.5kg with steep to

allow a drop distance of 300mm without friction

Weighing balance readable to an accuracy of 1g

Sieve 20mm with receiver

Straight edge

Moisture tins

Steel rods

Container for thorough mixing of soil

Palette knives or trowel

Brush


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Figure 24: MDD Apparatus-Light and Heavy Compaction

Procedure

Sample passing through 20mm sieve was weighed into four 4000g portions of

the passing material and put in different trays/basins

The mould was assembled on the base plate and weighed and the collar was

then fitted on the mould and the whole internal oiled to ensure soil doesn’t

stick to the mould

Each of the four 4000g portions was mixed thoroughly with percentage

amount of water in increasing order at an interval of 100ml

Compactions for the portions were done with the 4.5kg hammer in five layers

each layer 25 blows.

The collar was then removed carefully and excess soil on the mould trimmed

with a straight edge. The externally attached particles were cleaned with a

brush and the mould with wet soil weighed. The compacted soil was removed

from the mould using a steel rod

The specimen was broken down, the sample was then taken for moisture

content determination and the process repeated for all other portions

Dry densities were determined through calculations (considering mould

factor -0.99) and moisture contents obtained.


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4. Results and Analysis

4.1 Classification Tests

4.1.1 Particle Size Distribution

Since the sample constituted a fine grained soil, wet sieving was done on two

representative samples for comparison.

The following was obtained:

Sample 1:

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

0.01 0.1 1 10

% P

assi

ng

Sieve No. (mm)

Particle Size Distribution (S1- Neat)


F16/36598/2010 Page | 37

Sample 2:

The sample demonstrates that the material is well graded for a fine grained soil. The

silt content was however very high with approximately 90% being washed away from

a sample of 100g.

4.1.2 Atterberg Limits

4.1.2.1 Neat Sample

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

0.01 0.1 1 10

% P

assi

ng

Sieve No (mm)

Particle Size Distribution (S2-Neat)

15.918.5

20.2

23.2

0

5

10

15

20

25

65.5% 71.6% 83.0% 87.5%

Pen

etra

tio

n, m

m

Moisture Content, %

Liquid Limit- Neat Sample


F16/36598/2010 Page | 38

The liquid limit was found to be 83% and plastic limit as 40.6%

PI=83-40.6=42.4%

4.1.2.2 Plasticity index and Liquid Limit- 20% Blend

The one cone penetrometer method was used for this test due to the limited amount of

sample available.

The penetration was found to be 20.4 mm. To get the liquid limit, the moisture

content was multiplied by a factor of 0.9936 obtained from Table 1 (BS 1377-Part 2,

Factors for one-point cone penetrometer liquid limit test).

LL=0.9936 x 64.8 = 64.38%

PL=34.6%

PI=64.38-34.6=29.9%

4.1.2.3 Plasticity index and Liquid Limit- 40% Blend

The penetration was found to be 21.3 mm. To get the liquid limit, the moisture

content was multiplied by a factor of 0.9789 obtained from Table 1 (BS 1377-Part 2,

Factors for one-point cone penetrometer liquid limit test).

LL=0.9789 x 58.33 = 57.1%

PL=28.6%

PI=57.1-28.6= 28.5%

4.1.3 Plastic, Liquid Limit and Plasticity Index Variation


F16/36598/2010 Page | 39

From the above graph, it can be seen that

i) Liquid Limit gradually reduces with increase of the improvement agent. It

reduces from 83% in the neat sample to 57% in the 40% blended sample. A

26% decrease.

ii) Plastic limit also reduces from 40.6% in the neat sample of black cotton soil

to 28.6% in the 40% blend. A 12% decrease.

iii) Plasticity index decreases from 42.4% in the neat sample to 28.5% in the

40% blended sample. A 13.9% decrease.

4.2 Linear Shrinkage

=𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝐿𝑒𝑛𝑔𝑡ℎ−𝐹𝑖𝑛𝑎𝑙 𝐿𝑒𝑛𝑔𝑡ℎ

𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝐿𝑒𝑛𝑔𝑡ℎ 𝑥 100

Neat

=138.52−111.52

138.52𝑥 100= 19.5%

Neat, 82.95

20% Blend, 64.4

40% Blend, 57.1

Neat, 40.620% Blend, 34.54

40% Blend, 28.57Neat, 42.37

20% Blend, 29.8640% Blend, 28.53

0

10

20

30

40

50

60

70

80

90

Neat 20% Blend 40% Blend

Atterberg Limits Trend

LL PL PI


F16/36598/2010 Page | 40

20% Blend

=139−119.47

139𝑥 100=14.1%

40% Blend

=137.5−121.97

137.5𝑥 100= 11.29%

19.5

14.1

11.29

0

5

10

15

20

25


Linear Shrinkage Variation


F16/36598/2010 Page | 41

4.3 Compaction Related Tests

4.3.1 Maximum Dry Density and Optimum Moisture Content

4.3.1.1 Neat Sample

The maximum dry density was found to be 1330 kg/m3, and the optimum moisture

content as 31%. While the natural moisture content was 15.0%.

1160

1180

1200

1220

1240

1260

1280

1300

1320

1340

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00

Dry

Den

sity

, kg/

m3

Moisture Content, %

Maximum Dry Density (Neat)


F16/36598/2010 Page | 42

4.3.1.2 20% Blend


content as 29.0% while the natural moisture content was 12.9%.

4.3.1.3 40% Blend

1140.00

1160.00

1180.00

1200.00

1220.00

1240.00

1260.00

1280.00

1300.00

1320.00

1340.00

0 5 10 15 20 25 30 35 40 45

Dry

Den

sity

, kg/

m3

Moisture Content, %

Maximum Dry Density- 20% Blend

1160.00

1180.00

1200.00

1220.00

1240.00

1260.00

1280.00

1300.00

1320.00

1340.00

1360.00

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00

Dry

Den

sity

, kg/

m3

Moisture Content, %

Maximum Dry Density- 40% Blend


F16/36598/2010 Page | 43


content as 30.0%.

4.3.2 MDD and OMC Variation From Neat to 40% Blend

4.3.2.1 MDD Variation

The maximum dry density is seen to continually increase though at very small

intervals. It starts at about 1330 kg/m3 but drops at 20% blend and then increases

again at the 40% blend to 1340kg/m3.

This small variation between the dry densities of the samples show that there is

little/no change in the specific gravity of the materials even after firing.

1330

1324

1340

1315

1320

1325

1330

1335

1340

1345


MDD


F16/36598/2010 Page | 44

4.3.2.2 OMC Variation

The optimum moisture content also seems to be on a constant decline though the

range of variation is still small. The range was +/- 1.0 % from the average (30%).

4.4 California Bearing Ratio

4.4.1 CBR Theory 1

According to Patel and Desai (2010) a correlation between Plasticity Index,

Maximum Dry Density and Optimum Moisture Content. The correlation is found to

be more profound in CI and CH soils.

The relationship is as follows:

CBR (SOAKED) =43.907-0.093(PI)-18.78(MDD)-0.3081(OMC)

Where MDD is in g/cm3

Neat Sample

31

29

30

28

28.5

29

29.5

30

30.5

31

31.5


OMC


F16/36598/2010 Page | 45

CBR (SOAKED) = 43.907-0.093(42.4)-18.78(1.33)-0.3081(31)

=5.44 %

20% Blend

CBR (SOAKED) = 43.907-0.093(29.9)-18.78(1.324)-0.3081(29)

=7.33%

40% Blend

CBR (SOAKED) = 43.907-0.093(28.5)-18.78(1.34)-0.3081(30)

=6.85%

5.4

7.36.85

0

1

2

3

4

5

6

7

8


CBR Variation


F16/36598/2010 Page | 46

4.4.2 CBR Theory 2

According to Talukdar (2014) soaked CBR value could be determined from its soil

characteristics and gave the following equation from his research:

CBR (soaked) = 0.127(LL) + 0.00 (PL) – 0.1598(PI) +1.405(MDD) -0.259(OMC) +

4.618

Neat

CBR=0.127(82.95) + 0.00 (40.6) – 0.1598(42.4) +1.405(1.330) -0.259(31) + 4.618

=2.22%

20% Blend

CBR=0.127(64.4) – 0.1598(29.86) +1.405(1.324) -0.259(29) + 4.618

=2.37%

40% Blend

CBR=0.127(57.1) +– 0.1598(28.53) +1.405(1.340) -0.259(30) + 4.618

=1.42%

4.5 Test Summary

Table 2: Soil Properties Summary

Test Neat 20% Blend 40% Blend

Liquid Limit (%) 82.95 64.4 57.1

Plastic Limit (%) 40.6 34.54 28.57

Plastic Index (%) 42.37 29.86 28.53

Linear Shrinkage % 19.5 14.1 11.3

MDD (kg/m3) 1330 1324 1340

OMC (%) 31 29 30

CBR (%) 5.44 7.33 2.49

Swell 0.86 2.49 0.038


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________________________________________________________________________

Low volume roads are described as those with traffic of less than 0.25 Million ESA

during its design life. Taking into account that the thickness layer of black cotton soil in

the area is only 2ft and the rock extends to more than 10ft from the ground level, top soils

stripping and stabilisation of the material in order to reduce shrinkage and swell would be

appropriate.

The choice on whether to use the 20% or 40% blend will however be highly subjected to

economic viability of the two alternatives and further stabilization.

According to the Kenya Road Design Manual-Part III

Table 3: Improved Subgrade Classes

Subgrade

Class

CBR design Density for

determination of

CBR design

(% of MDD of BS

Heavy)

Wet

Climatic

Zones

4 days

soaked

value

Dry Climatic Zones

At

OMC

4 days soaked

value

S15 Min 15 Min 15 Min 7 95

S7 7 to 14 7 to 14 3 to 14 93

The maximum PI of the improved sub-grades should be 30 and 25 for S7 and S15

respectively; and the maximum swell should be 2.0% and 1.5% respectively.

The 20% Blended sample would pass for the CBR value but there would be a shortfall

when it comes to the swell characteristics.

This therefore means that the test material for this project needs to be stabilized further.

This could be done chemically by use of lime or cement. Lime would however be

advocated for due to the dry nature of the area and the tendency of cement to crack.

The stabilization should be aimed at further reducing the swell, shrinkage and increasing

its bearing capacity.

The increase in swell in the 20% Blend could be attributed to the increase in swell

potential caused by compaction. (Bowles, J.E., 1984-pg 207).


F16/36598/2010 Page | 48

4.6 Cost Analysis

The cost comparison between, cutting to spoil of the black cotton soil, mechanically

stabilizing are as follows per kilometre of construction:


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5. Project Constraints

During the project period, a number of constraints were encountered. These came about

during the testing period and obtaining the test results.

5.1 Storage of Material

The material was stored in the Highways Engineering Laboratory Storage area at the

University of Nairobi, Main Campus. Problems encountered at this stage was a result of

the laboratory undergoing a cleanup process of the waste material.

Some of the material was accidentally discarded despite having appropriate labels

showing they were still in use and tests on them were not completed. This led to the

testing sample being reduced and hence some of the tests not being done

comprehensively.

During cleaning of the storage area for equipment, some of the samples were

contaminated with the water used. This therefore exposed the material to vulnerability

and being unreliable especially when it came to determination of natural moisture

contents. Computations which required natural moisture content such as the CBR were

therefore compromised and gave misleading results.

5.2 Equipment Unavailability

During the project period, especially towards the latter stages of the project proved to be

unavailable for use and on availability, it was out of order. This affected the programme

for making of the stabilizing agent through use of a kiln with a capacity of reaching

800⁰c.

The kiln that was used to make the first batch of stabilizing agent was also limiting as it

could only reach a temperature of 500⁰c despite the desirable 800-900⁰c.

Equipment to perform volumetric shrinkage was not available. This needed

customization but the time and resources allowed for this project could not allow.

5.3 Faulty Laboratory Equipment


F16/36598/2010 Page | 50

Some of the laboratory equipment proved to be faulty during operation. Such included

the moulds used for compaction tests i.e. the maximum dry density test mould and the

CBR mould.

Some of the moulds could not be secured well and during compaction some elements of

the sample would leak and disperse from the bottom.

During testing of the CBR, some of the moulds needed to be forcefully extracted from the

base plate and this put question to the integrity of the material.


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6. Recommendations and Conclusion

6.1 Recommendations

From the conducted tests and the results that were obtained:

It is evident that the mechanical stabilization of black cotton soil (from Syokimau,

Machakos County, Kenya) with fired clay from the same area was not sufficient to enable

the material to be used as sub-grade material for low-volume roads.

Taking into consideration that the bedrock was only two feet (2 ft) from the original

ground level cutting-to-spoil the black cotton would have been a more viable and

economical decision.

However, in other areas where the black cotton soil penetrates to greater depths, chemical

stabilization in addition to the mechanical stabilization should be investigated.

Since the mechanical stabilization was able to reduce the plasticity index from 42.37% to

28.53% blend which is allowable taking into account the Kenya Roads Design Manual-

Part III; lime should be considered to reduce the swell into tolerable limits, increase the

dry density considerably and increase the bearing strength characteristics of the stabilized

material.

6.2 Conclusion

The aforementioned results in relation to the objectives of the project show that black

cotton soil can be stabilized without input of borrowed material. However, it may not be

within the prescribed limits to act as a sub-grade without foreign material being input.

The optimum ratio was found to be that with the 20% blend in terms of bearing strength

and reduction in plasticity. Increase in the stabilizing material did not indicate a

significant change.

All the engineering properties of the original sample changed for the better. This was

with exception of the maximum dry density and optimum moisture content for

compaction.


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7. References

1. Donald R. Snethen, "Technical Guidelines for Expansive soils In Highway subgrades",

US Army Engineer waterways Experiment station, June 1979

2. Das, M.B., 1984. Principles of geotechnical engineering. Brooks and Cole Inc., New

York, pp: 258-287.

3. Hauck, G.F., 1959. Swelling and intrusion characteristics of undisturbed Permian clay.

M.Sc Thesis, Department of Architectural Engineering. Oklahoma State University, pp:

53.

4. Gromko, G.J., 1974. Review of expansive soils. J.Geotechnical Eng. Division. June

ASCE,pp: 667-689.

5. Kalantari, B., 1991. Construction of foundations on expansive soils. M.Sc Thesis,

Department of Civil Engineering University of Missouri Columbia,Missouri, pp: 35-44.

6. O’Neill, M.W. and N. Poormoayed, 1980. Methodology for foundations on expansive

clays. J. Geotechnical Eng. Divis. Dec. GT12., PP: 1345-1366.

7. Ola S.A (1983). The geotechnical properties of the black cotton soil of Northeastern

Nigeria. In Tropical soils of Nigeria in Engineering Practice, Ola S.A. (Ed). A. A.

Balkema Publishers, Rotterdam. Pp.85-101.

8. Dana, E.S. (1892) Dana's system of mineralogy, (6th edition), 690-691,695-697.

9. Bowles J.E. (1984) Physical and Geotechnical Properties of Soils.

10. Dr.Dilip Kumar Talukdar, A Study of Correlation between CBR Value with other soil

properties, January 2014.

11. Black and Lister, CBR Determination through Plastic Limit and Liquid Limit, 1979.

12. Patel R.S. and Desai M.D., CBR predicted by Index Properties of Soil for Alluvial Soils

of South Gujarat, Indian Geotechnical Conference, Proc. IGC, Vol. 1,pp 79-82.


F16/36598/2010 Page | 53

8. Appendices

8.1 Particle Size Distribution

NB: All measured weights are in grams

Neat

Table 4: Particle Size Distribution- Sample 1

Sample Weight

(g)

10.4

Seive

(mm)

Retained Passing

%

Passing %

14 100.0%

10 4.1 39.4% 60.6%

5 1.5 14.4% 46.2%

2.36 0.78 7.5% 38.7%

1.18 0.49 4.7% 33.9%

0.6 0.48 4.6% 29.3%

0.425 0.3 2.9% 26.4%

0.3 0.35 3.4% 23.1%

0.15 1.02 9.8% 13.3%

0.075 1.06 10.2% 3.1%

<0.075 0.32 3.1% 0.0%

100.0%

8.2 Plastic Limit, Liquid Limit and Plasticity Index

8.2.1 Neat

Table 5: Liquid Limit, PI and PL- Neat Sample

LL LL LL LL PL PL

Penetration 15.9 18.5 20.2 23.2 - -

Dish No 99 14 L T 88 Q

D+Ws 76.5 62.9 53.3 65.3 29.7 30.8

D+Ds 57.9 45.8 31.4 49.2 29 30.2

D wt 29.5 21.9 5 27.8 27.3 28.7


F16/36598/2010 Page | 54

Ww 18.6 17.1 21.9 16.1 0.7 0.6

Ds 28.4 23.9 26.4 21.4 1.7 1.5

MC 65.5% 71.6% 83.0% 87.5% 41.18 40.00

PL 40.59

LL 82.95

PI 42.36

8.2.2 20% Blend

Table 6:Liquid Limit, PI and PL- 20% Blend

Dish

No

IP AD AI IK

D+ws

(g)

32.7 21.9 11.2 7.1

D+Ds

(g)

29.1 14.9 10.6 6.5

D wt

(g)

22.5 4.1 8.7 4.9

Ww

(g)

3.6 7 0.6 0.6

Ds (g) 6.6 10.8 1.9 1.6

MC

(%)

54.55 64.81 31.58 37.50

From One Cone penetrometer

(20.4)

L.L 64.40

PI 29.86

8.2.3 40% Blend


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Table 7: Liquid Limit, PI and PL- 40% Blend

LL LL LL PL PL

Penetration 25 21.3 20 - -

Dish No AD IP IC T JJ

D+WS (g) 14.3 33.9 47 9.8 11

D+DS (g) 10.7 29.7 37.7 9.4 10.2

Dish wt (g) 4.1 22.5 23.2 8 8.7

Water

Content (g)

3.6 4.2 9.3 0.4 0.8

Ds (g) 6.6 7.2 14.5 1.4 1.5

MC (%) 54.55 58.33 64.14 28.57 53.33

One Cone Pen

(21.3)

LL 57.1

PI 28.53

8.3 Maximum Dry Density and Optimum Moisture Content

8.3.1 Neat

Table 8: MDD and OMC Data Sheet- Neat Sample

Vol of spec 956

Water content

(cm3)

200 300 400 500 600 700 NMC

Mould Weight

(g)

4090 4090 4090 4090 4090 4090

mould+ sample

(g)

5525 5585 5740 5720 5740 5680

Sample Weight

(g)

1435 1495 1650 1630 1650 1590

tin no 62 151 133 77 197 61 183

tin+wet

sample(g)

208.3 244.3 296 302.2 214.2 277.1 144.4

tin+dry(g) 187.21 215.24 251.89 257.6 180.1 221.43 135.4

tin weight(g) 90.5 104.2 104.9 120.1 74.6 89.6 75.4

weight of dry

soil(g)

96.71 111.04 146.99 137.5 105.5 131.83 60


F16/36598/2010 Page | 56

weight of

water

21.09 29.06 44.11 44.6 34.1 55.67 9

m.c (%) 21.81 26.17 30.01 32.44 32.32 42.23 15.00

Density

(g/cm3)

1.50104

6

1.56380

8

1.72594

1

1.70502

1

1.72594

1

1.66318

Bulk Density

(kg/m3)

1501.04

6

1563.80

8

1725.94

1

1705.02

1

1725.94

1

1663.18

dry density

(kg/m3)

1232.31 1239.43

7

1327.55

7

1287.42

7

1304.34

7

1169.37

1

MDD 1330

OMC 31

8.3.2 20% Blend

Table 9: MDD and OMC Data Sheet- 20% Blend

Vol 956

mould

+sample

(g)

Sample

Weight

(g)

bulk

density

(kg/m3)

dry

density

(kg/m3)

tin

no#

tin +

wet

(g)

tin+dry

(g)

h20

content

(g)

tin

weight

(g)

dry

soil

(g)

m.c

(%)

5616 1508 1577.41 1303.02 110 214.98 195.78 19.2 104.6 91.18 21.06

5740 1632 1707.11 1324.30 201 178.66 155.37 23.29 74.8 80.57 28.91

5764 1656 1732.22 1318.13 204 233.88 196.21 37.67 76.3 119.91 31.42

5800 1692 1769.87 1278.01 100 280.68 232.83 47.85 108.5 124.33 38.49

5684 1576 1648.54 1166.07 89 314.39 248.28 66.11 88.5 159.78 41.38

NMC

Tin No 195

Tin+ Wet

(g)

167.27

Tin+ Dry(g) 156.74

Tin Wt (g) 75.1

Dry Soil (g) 81.64

Wet (g) 10.53

M.C (%) 12.9


F16/36598/2010 Page | 57

8.3.3 40% Blend

Table 10: MDD and OMC Data Sheet- 40% Blend

Vol of

mould

0.956

mould

+sample

(g)

Sample

Weight

(g)

bulk

density

(kg/m3)

dry

density

(kg/m3)

tin

no#

tin +

wet

(g)

tin+dry

(g)

h20

content

(g)

tin

weight

(g)

dry

soil

(g)

m.c

(%)

5890 1410 1474.90 1249.18 133 228.4 209.5 18.9 104.9 104.6 18.07

5985 1505 1574.27 1305.68 110 223 202.8 20.2 104.6 98.2 20.57

6140 1660 1736.40 1341.54 197 214 182.3 31.7 74.6 107.7 29.43

6130 1650 1725.94 1307.01 100 239.1 207.4 31.7 108.5 98.9 32.05

6100 1620 1694.56 1263.07 204 265.2 217.1 48.1 76.3 140.8 34.16

6050 1570 1642.26 1183.36 183 273.3 218 55.3 75.4 142.6 38.78

MDD

(kg/m3)

1340

OMC (%) 30

MDD

(kg/m3)

1324

OMC 29

nmc

tin no 201

tin+wt (g) 122

tin+dry (g) 118.1

tin wt(g) 74.8

water

content(g)

3.9

dry soil (g) 43.3

NMC (%) 9.01

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