raju-marine clay with saw dust final

Stabilization of Marine Clay using Saw Dust

A LABORATORY STUDY ON THE AFFECT OF SAW DUST ON THE PROPERTIES OF MARINE CLAY

A project report submitted in partial fulfillment of the requirement for the award of degree of

BACHELOR OF TECHNOLOGY

IN

CIVIL ENGINEERING

By

S.KANAKA RAJU

Under the esteemed guidance of

Dr. D. KOTESWARA RAO

Associate Professor in Civil Engineering

DEPARTMENT OF CIVIL ENGINEERING

UNIVERSITY COLLEGE OF ENGINEERING: KAKINADA

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY KAKINADA

KAKINADA – 533 003, ANDHRA PRADESH, INDIA

April - 2012


CERTIFICATE


Certificate that the project report entitled “A LABORATORY STUDY ON THE AFFECT OF SAW DUST ON THE PROPERTIES OF MARINE CLAY” submitted by S.KANAKA RAJU bearing Roll No 07063A1470 in partial fulfillment for the award of the degree of Bachelor of Technology in Civil Engineering to the faculty of Engineering and Technology of Jawaharlal Nehru Technological University, Kakinada in record of the bonafide work carried out by them under my guidance and supervision.

The results presented in the report have not been submitted to any other University or Institute for the award of any degree.

Date:

Signature of the

Project Guide: External Guide:

Dr.D. KOTESWARA RAO Sri N.VIJAYANANDProject advisor, Sr. ENGINEERAssociate Professor, SHELADIA ASSOCIATEA,USA., Bangalore. Indore, M.P (State)Department of Civil Engineering, University College of Engineering,JNTU, Kakinada.

ACKNOWLEDGEMENT


I am very much thankful to my guide sir Dr. D. KOTESWARA RAO and Sri N.VIJAYANAND as Academic supervisor for living me valuable guidance and keen interest in shaping this project report.

I am thankful to Dr. P. Subba Rao Head of the Civil Engineering Department for availing a favorable atmosphere to carry out this assignment.

I am thankful to Dr. GVR Prasad Raju, Prof. K. Purnanandam, Dr. K.Ramu, The faculty of Geotechnical Engineering Division, for their constant encouragement during the course of my Project work.

I am thankful to Prof. V. Ravindra, Prof. K.V.S.G.Murali Krishna, Dr. V. Srinivasulu, Sri B. Krishna Rao, Smt. V. Lakshmi , Dr.K.PadmaKumari. For their moral support.

I am thankful to Sri K. Srinivasa Rao, Tech. Asst., Department of Civil Engineering, for his helping nature through my course of Project work. I am thankful to Supporting staff of Soil mechanics laboratory and Civil Engineering Department office, JNTU, KAKINADA for their kind co-operation during my project work.I am gladly acknowledge all those who have helped me directly or indirectly during my project work. S. Kanaka Raju

Roll.No.07063A1470

CONTENTS


PAGE No.

CHAPTER 1: INTRODUCTION

1.1. General1.2. Discussion of Various Investigations on marine clay1.3. Need for the Study1.4. Objectives of the Study1.5. Organization of the Project

CHAPTER 2: REVIEW OF LITERATURE

2.1 GENERAL2.2 MARINE CLAY

2.2.1 General2.2.2 Origin of Marine Clays2.2.3 Behaviour of Marine Clay2.2.4 Studies on marine clay

2.3 Problems associated with Marine Clays2.3.1 General2.3.2 Damages to the Pavements Sub grades

2.4 Remedial measures to overcome problems of marine clay soils

2.4.1 Soil Replacement2.4.2 Sand Cushion Method2.4.3 Stiffening the Foundation and Super structure2.4.4 Mat Foundation2.4.5 Stone Columns2.4.6 Band Drains or Wick drains 2.4.7 Heat Treatment

2.5 STABILISATION OF MARINE CLAYS2.6 SAW DUST

2.6.1 USES OF SAW DUST


CHAPTER 3: STUDY METHODOLOGY

3.1 VARIABLES TAKEN FOR THE STUDY 3.2 MATERIAL USED

3.2.1 Marine Clay 3.2.2 Saw Dust

3.3 LABORATORY STUDIES3.3.1 Liquid limit 3.3.2 Plastic limit3.3.3 Shrinkage limit3.3.4 Free swell index3.3.5 Proctor’s standard compaction Test3.3.6 Unconfined compressive strength 3.3.7 California bearing ratio Test3.3.8 General3.3.9 Visual characteristics

3.4 Laboratory Testing3.4.1 Grain Size Analysis (Sieve Analysis)3.4.2 Water content3.4.3 Consistency Limits & Indices

3.4.3.1 Liquid Limit Test3.4.3.2 Plastic Limit3.4.3.3 Shrinkage Limit

3.4.4 Compaction Test ( Fig 3.1 )3.4.5 California Bearing Ratio (CBR) Test 3.4.6 Tri-axial Test 3.4.7 Specific Gravity Test3.4.8 Differential Free Swell Test

CHAPTER 4: PRESENTATION AND DISCUSSIONS ON RESULTS

4.1 GENERAL4.2 LABORATORY TEST RESULTS


4.3 PROPERTIES OF MARINE CLAY+SAW DUST

CHAPTER 5: CONCLUSIONS

5.1 GENERAL5.2 CONCLUSIONS5.3 FURTHER SCOPE OF WORK

CHAPTER 6: REFERENCES

CHAPTER-1

INTRODUCTION


1.1 GENERAL

There are many deposits of fine clays on coastal corridor and those soils are suffering from high saturation, low density, low shear strength, sensitivity, and deformation problems and are normally consolidated. Such soils are generally termed as marine clays. In any developing country infrastructure, transportation, and communication facilities play a major role for the development. The properties of marine soil depend significantly on its initial conditions. The properties of saturated marine soil differ significantly from moist soil and dry soil. Marine clay is microcrystalline in nature and clay minerals like chlorite, kaolinite and illite and non clay minerals like quartz and feldspar are present in the soil.

In general, the natural water content of the marine clay is always greater than its liquid limit. The marine clays are not suitable as pavement sub grade & foundation soil beds and pose problems due to their inability of strength criteria. More and more construction projects are encountering soft clays and hence there is a need to better quantifying the properties of marine clays.

These soils are widely occupied in coastal corridor and not easy to avoid marine clay regions for the construction of pavements and foundations due to the population density. India being peninsular country have a large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are found in the states of west Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat in India. Hence, for having smooth transportation it needs to improve properties of marine clays. Marine clays are highly compressible in these regions.

The development of any country depends on the transportation facilities and the construction projects. For the projects to be successful, the


soil used for the foundation beds must be strong which requires in improving the properties of soil.

A substantial literature has concluded the severity and extent of damage inflicted by soil deposits of selling nature, to various structures, throughout the world (Ganapathy, 1977; Jones and Jones, 1995; Abduljauwad, 1995; Osama and Ahmed, 2002; Zhan, 2007). The loss caused due to damaged structures proved the need for more reliable investigation, of such soils and necessary methods to eliminate or reduce the effect of soil volume change.

Many innovative foundation techniques have been devised as a solution to the problem of expansive soils. The selection of any one of the techniques is to be done after detailed comparison of all techniques for the well suited technique for the particular system. The various additives used for stabilizing expansive soils are lime, calcium chloride, rice husk ash, fly ash, gypsum and others.

1.2 IMPORTANCE OF STABILIZATION

Stabilization is the process of improving the engineering properties of the soil and thus making it more stable by adding different types of additives. By stabilization, load bearing capacity of the soil will be enhanced. Soil stabilization is used the permeability and compressibility of the oil mass in earth structures and to increase its shear strength.There are different types of stabilization. They are

a) Mechanical stabilizationb) Cement stabilizationc) Lime stabilizationd) Bituminous stabilizatione) Chemical stabilizationf) Thermal stabilization


g) Electrical stabilization

Infrastructure projects such as highways, railways, water reservoirs, reclamation etc. requires earth Material in very large quantity. In urban areas, borrow earth is not easily available which has to be hauled from a long distance. Quite often, large areas are covered with highly plastic and expansive soil, which is not suitable for such purpose. Extensive laboratory /field trials have been carried out by various researchers and have shown promising results for application of such expansive soil after stabilization with additives such as sand, silt, lime, fly ash, rise husk ash etc.

For a successful construction of road network, the pavement should be located on soil, which requires the least thickness above it. The ancient road building material is soil itself on which the pavement is placed. Hence for the stability and performance of a road, soil should be stable and strong. The performance of the pavement largely depends on the strength of the sub grade. However, in nature problematic soils do exist which are not suitable for any civil engineering construction even for road pavements. Such soils have to be treated with different types of materials to produce a new material, which imparts stability and durability to the soil.

This work presents the result of laboratory investigations carried out to understand the characteristics of marine clay with stabilizing agents like Saw Dust.

1.3 NEED FOR STUDY Continued efforts have been made all over the world to devise ways to means to solve the problems of marine clays. Placement of adequate surcharge load, chemical stabilization and using various reinforcement techniques are some of the tried and tested remedial measures to avoid problems posed by the marine clays. The road construction technology is


subjected to change the scope up with changing vehicular pattern, construction materials, sub grade condition and also the conditions of foundation soils. Majority of the pavement failures could be attributed to the presence of poor and compressible sub grade conditions is one such problematic situation. Hence the growing demand for the construction of inexpensive roads, which answer the requirements of traffic. To realize the objective, new methods and new materials of construction have been continuously explored.

Saw dust is a byproduct from Timber industries, Wood cutting factories, As Saw dust is freely available. It can be used for stabilization of expansive soils for various uses. Saw dust by itself has little cementitious value but in the presence of moisture it reacts chemically and forms cementitious compounds and attributes to the improvement of strength and compressibility characteristics of soils.

This work presents the laboratory investigations carried out to understand the characters of the marine clay soil when Saw dust is added to the soil.

1.4 OBJECTIVES OF THE STUDY

The objectives of the present experimental study are To determine the properties of the marine clay and Saw dust. To evaluate the performance of marine clay when stabilized with

Saw dust as an admixture and its suitability for the pavement sub grade.

To evaluate the performance of stabilized marine clay with an optimum of Saw dust on the addition of lime as an additive and it suitability for the pavement sub grade.


1.5 ORGANIZATION OF THE PROJECT

In addition to the present introductory chapter, this work has been presented in six chapters as follows. 2. Chapter : an overview of various remedial measures to overcome the problems posed by the marine clay is made with a view to identify the deficiencies in the carried out so far and defining the specific scope of present study.

3. Chapter : It presents the details of laboratory experimentation, where the material properties and detailed testing procedures are discussed. 4. Chapter : In this chapter the foundation soil beds on untreated and treated marine clays were presented and the procedures adopted for the construction of foundation soil beds along with the in-situ testing results were also given in this chapter. 5. Chapter : All the results obtained from laboratory and in-situ were presented in this chapter. 6. Chapter : Presents the details of economic analysis carried out for the untreated and treated marine clay flexible pavements in the field.

The results are concluded in fifth chapter which gives a brief overview of the work summarizes the observed performances of additives like Saw dust and lime.

All the references that were used in this project are included in the seventh chapter.

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CHAPTER-2

REVIEW OF LITERATURE

2.1 GENERAL

The need and the objectives of the present study were established in the previous chapter. The review of literature on marine clay and granulated blast furnace slag was presented in this chapter. Soft marine clay is very sensitive to change the stress system, moisture content and system chemistry of the pore fluid. Geotechnical engineers feel a necessity to improve the behavior of these deposits using anyone of the available ground improvement techniques. Fig 2.1 shows the marine clay corridor of India.

Fig: 2.1 Marine Clay Corridor of India


2.2 MARINE CLAY

2.2.1 General

Marine clays from one of the important groups of fine grained soils. Lost of civil construction activities take place in such marine clays throughout the world. Most of the marine clays are highly compressive and of low strength.

India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the states of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat (Fig 2.1). Marine or soft clays existing in these regions are weak and compressible in nature.

Marine clay is uncommon type of clay and normally exists in soft consistency. Marine clay deposit of east coast of India was used for the testing with the aim to investigate its engineering properties. During construction of well foundation for a marine structure in the offshore area (about 10 m off the shoreline) of Visakhapatnam port at East coast of India, the subsoil was excavated. The soil collected from a depth of about 10 – 12 m was used for investigation.

2.2.2 Origin of Marine Clays

Marine soil deposits have been found both on the coast and in several offshore areas spread over many parts of the world. When clay particles precipitate in salt water, there is a tendency for the clay particles to flocculate and stick together giving rise to some sort of edge-to-face arrangement. As a result, clay, silt, and fine sand particles settle almost at the same rate and the final sediment formed consists of particles with a very loose card house-like structure (Bjerrum and Heiberg, 1971). Hence the marine sediments


can be considered as loose sediments, usually formed with high void ratios. Problems are associated with these fine-grained soils deposited at a soft consistency. Fine-grained soils are very sensitive to changes in the stress system, moisture content and system chemistry of the pore fluid. In addition to these, the problems arising out of high compressibility and low shear strength of these weak marine deposits expose geotechnical engineers to considerable changes in the construction of various coastal and offshore structures. The performance of these soft fine grained deposits under different conditions of environment varies over wide limits. In order to improve the engineering behavior of soils, several improvement techniques are available in geotechnical engineering practice. The fact that the selection of anyone of these methods for any problem can be made only after a comparison with other techniques proves that the method is well suited for a particular system.

2.2.3 Behavior of Marine Clay

The marine clays are highly compressible soft clays and also it exhibits moderate swelling when comes in contact with moisture. This behavior is due to the presence of clay minerals with expanding lattice structure. The marine clay is very hard when it is dry but loses its strength on wetting. The marine clay got cracks as shown in the plate 2.1 on drying and in the worst cases the width of the cracks is almost 250 mm to 500 mm and travel down to 1.00m beneath the ground level.The consistency limits of the marine clay are as follows: Liquid limit is 74%, Plasticity index is 47%, Shrinkage limit is 12% and Specific gravity is 2.62


2.2.4 Studies on marine clay

Marine clay is a type of clay and normally possesses soft consistency Marine clay deposits of Kakinada were used for the testing with the aim to investigate its Engineering properties (Penner and Bum(1978); Tan(1983); Narasimha Rao and Swamy(1984); Shridharan et al.(1989); Chong (1991); Buddhima Indraratna et al.,(1991); Anandarajah and Chu (1997) ; Chong et al.,(1998); Thiam-Soon Tan et al.,(2002); Chu et al.,(2002); Supakij Nontananandh et al.,(2004); Oh and Chai (2006); Matchala Suneel et al.,(2008); Basak and Purkayastha (2009); Gang Ren (2010)) and further, made suitable for foundation constructions over it and also for the flexible pavement sub grades.

Figure 2.1 Marine Clay

Law (1979) reported that the undrained cohesion of the marine clay was determined using triaxial, vane shear test and presented the effect of the consolidation pressure on the undrained shear strength of soft clay.

A research has been done on the Physico-Chemical effects on the engineering behavior of Indian marine clays by Rao, M.S et al., (1992).


Shridharan et al., (1989) reported the engineering properties of Cochin and Mangalore Marine Clays. Hyde et al., (1993) presented the engineering properties and stability criteria for marine clay under cyclic loading.

Narasimha Rao et al., (1996) stated that the Permeability (k) values shows an enormous improvement by using lime column technique and the k value was improved up to 23 times. This shows good promise for improving the soft coastal deposits and the offshore deposits. Thiam-Soon et al (2002) reported on improving the strength of the marine clay by the stabilization technique. Chu et al., (2002) reported the consolidation and permeability properties of the Singapore marine clay based on the laboratory and field investigations.

Balasubrahmaniam et al., (2003) proved the effects of additives on Soft Clay behaviour and concluded that the strength characteristics of the soft clays are improved by using various additives. Supakij Nontananandh et al., (2004) reported the efficacy of the stabilization techniques on strength characteristics of the marine clay. Oh and Chai (2006) presented the engineering properties and the characterization of marine clay for road embankment design in coastal area and the engineering properties of the marine clay were improved using various stabilization techniques. Matchala Suneel et al., (2008) represented the compressibility characteristics of Korean marine clay. Sing et al., (2008) reported an improvement in the engineering properties of peat soils stabilizing with cement and ground granulated blast furnace slag and proved a remarkable increase in the pH and unconfined compressive strength, significant reduction in linear shrinkage, compressibility and permeability of the stabilized peat soils.

Basak and Purkayastha (2009),reported that the Engineering characteristics of marine clay collected form Visakhapatnam, India


and the physical, chemical and mineralogical properties were presented and the strength, stiffness of the soil water matrix were established. Tanit Chalermyanont et al., (2009) represented that the properties of marine clay indicates that it has significant advantages over the lateritic soil as land fill liner material.

2.3 Problems associated with Marine Clays

2.3.1 General

Among the various damages, the damage caused by the

marine soft soils to the pavements and also for foundation beds are

mentioned here in detail.

High compressibility and moderate swelling nature of the marine clay soils on inhabitation of water during the monsoon and reduce density or shrinkage occurs because of evaporation of water in summer and become hard due to increased density and this trend of soil decreases with depth. The volumetric deformation in these soils is attributed to seasonal variations in the ground water profile resulting in changes in moisture content.

During summer, polygonal shrinkage cracks occurs near the surface, extending to depth of about 1.5m, indicating a high potential for compressibility. The depth of cracking indicates the depth of active zone in which significant volume change occurs, which is defined as thickness of soil in which moisture deficiency exists.

The entire stratum of marine clay soils in the field may not be active. Besides, as most soils do not respond quickly to the climate changes, the depth of active zone is greater than the depth of seasonal moisture fluctuations. The buildings in marine soils have posed serious problem of distortion and cracking throughout the


world because of unlimited quantity of water being readily available to the foundation soil.

2.3.2 DAMAGES TO THE PAVEMENT SUBGRADES

Majority of the pavement failures could be attributed to the poor sub grade conditions and marine clay is one such problematic situation (Evans and McManus, 1999). Roads running through marine clays regions are subjected to severe unevenness with or without cracking, longitudinal cracking parallel to pavement centerline, rutting of pavement surface and localized failure of pavement associated with disintegration of the surface. The extensive damage to highways running over expansive and high compressible soil sub-grades (plates 2.2 & 2.3) is estimated to be in billions of dollars all over the world. Even railway tracks are no exception and are affected by appreciable movements due to the nature of high compressibility of the marine clay solis.

2.3.3 Damages to the building foundations

Buildings have presented the most obvious cases of damage caused by high deformation of foundations on marine clays (Plate 2.3). Light structures resting on footings in marine clays have been badly cracked by foundation movements in both horizontal and vertical directions. In some cases piles have been completely sheared off. Huge damages have been documented by researchers from several countries on deformation of soft soils (Christodulias and Gasios, 1987).


Figure 2.3.3 Typical Settlement Cracks in Super Structure Laid on

Marine Clay Foundation Bed.

2.4 Remedial measures to overcome problems of marine clay soils

If soil has a high deformation, the preventive measures are required. These measures can be broadly classified into the following categories:

Avoiding highly compressible soils Alterations to these soils

In case of foundations, Sand Cushion method, Stiffening the foundation by adopting Alterations, Mat Foundations, Heat treatment, Chemical stabilization, soil replacement technique are some of the remedial measures to overcome the problems of compressible marine clay soils.

In case of Pavement subgrades, stabilization techniques can be adopted using various industrial waste considering the economy and also chemical additives for easy mixing and early results. The reinforcement techniques also plays vital role in improving the load carrying capacity of the marine clay beds.

2.4.1 Soil Replacement


It consists of replacing the weak marine clay by using the rich soils available within the vicinity. So that the bearing capacity of the foundation bed or subgrade of the flexible pavement can be improved and also the deformations can be controlled up to some extent.

Chen (1988) claimed that the depth of soil replacement should be exercised to prevent entry of surface drainage from reaching the underlying expansive soil. This method becomes uneconomical if expansive soil or soft soil extends to a great depth (Nelson, 1991).

2.4.2 Sand Cushion Method

In this method, the entire depth of the marine clay stratum or a part there of is removed and replaced with a sand cushion, compacted to the desired density and thickness. The deformation varies inversely as the thickness of the sand layer and directly as the density of the sand. Provision of sand cushion is probably based on the assumption that it would absorb upward and lateral deformations. The sand cushion method thus bristles with severe limitations particularly when it is adopted in deep strata. Foundation engineers often suggest some arbitrary thickness for sand cushion. (Bart facilities standards, standard specification,2008.Swell shrink behavior of expansive soils under rice husk ash cushions, international association for computer methods and advances in geo mechanics,2008.Evaluation of drying and wetting cycles with soil cushion to mitigate the potential of expansive soil in upper Egypt, Aly ahmed,EJGE,2009.)

2.4.3 Stiffening the Foundation and Super structure

Provision of RCC bands in the foundation, plinth and lintel levels is also suggested as cracks control measures in buildings. But this practice has not produced the desired and anticipated results.


Even heavy reinforcement at the foundation level will not prevent cracking due to doming pattern of heaving (Agarwala and Khanna, 1969; Winnfred, 1969).

2.4.4 Mat Foundation

Mat foundation receives and transmits the entire structural load to the under slab soil. These foundations may be economical on long term basis, but involves high initial cost and would be a costly proposition in developing countries like India. Lytton and Woodburn (1973) and Chen (1988) reported that the condition of buildings built using stiffened slab system is satisfactory. However, Zeitlen (1969) claimed that mat foundation is worth considering for small and simple structures or for separated units of less than 3m x 6m, otherwise it would be expensive to contain differential movements.

2.4.5 Stone Columns

The stone column technique was increasingly used for improving the load bearing capacity and to reduce the settlements of soft soils. This technique was used effectively for the foundations of structures, earthen dams and raft foundations, where huge settlement is possible. Dipty Sarin Isaac and Girish (2009), presented the laboratory investigation on stone columns for improvement of soft clay, using stones, gravel, river sand, sea sand and quarry dust and it was proved that the quarry dust was more effective than the other materials for improving the load deformation characteristics of the soft soil.

In Kakinada Sea Ports Limited, Kakinada, Andhra Pradesh, India, the stone columns techniques was experimented to observe the efficiency of stone columns in soft marine clay using boulder of various sizes, but this techniques was failed due to un-confinement and the compressible nature of the marine clay (Ambily and Gandhi, 2004).


2.4.6 Band Drains or Wick drains

Geo-composites formed of hallow cored, geotextile wrapped drainage element (geo-net) inserted vertically into soft ground to speed up the consolidation process. Band drains are typically used in constructing embankments over compressible and water saturated soils to improve stability and accelerate settlement.

These soils have a weak porous structure, usually filled with water (pore water). When such soils are loaded by a superimposed embankment or structure the water is squeezed out. However, because of the impermeable nature of some soils, this could take time, hence causing instability and long term settlement problems for any structure built on top.

Band drains are installed vertically from the working plate form deep into the ground and act as wicks providing a route for the water to drain out quickly either to the surface or a more permeable stratum at depth. This process speeds consolidation of the soil and minimizes settlement of the superimposed embankment or structure.

Band drains can be used in combination with vibro stone and vibro concrete columns for strengthening purposes and drain and horizontal to dissipate the pore water pressure. They are also commonly used in conjunction with basal reinforcement, which provides short term stability of the embankment while the band drains contribute to accelerate consolidation of the soft deposits underneath.

Band drains were successfully used in the road embankment in Kakinada Sea Ports limited, Kakinada, Andhra Pradesh, India and also the band drains were used in the approach embankment either sides of the river bank in the construction of the Toome bypass in Northern Ireland.


Band drains and basal reinforcement were utilized in the construction of a distributor road over embankments for new housing development at Dering Way near Gravesend, in the Thames Gateway. The band drain solution was selected because it was economically advantageous. The faster consolidation settlement enabled the embankment to be used as the main site haulage road during the construction phase.

CIRIA Publication (2002); BS EN 15237 (2007); TRL Projects Reports PPR 341(2008), represented the advantages of using the band drain in soft soils.

2.4.7 Heat Treatment

Russians have developed thermal stabilization technique to stabilize the soft clays. This technique consists of blowing preheated air under pressure through boreholes. The plasticity of soil decreases as temperature increases until 500 0c and soil become non-plastic, but the effective depth of burning with mobile furnace is hardly 2, 5 inches and consequently the technique is uneconomical and not possible in case of marine clay because the moisture content increases with depth of soil strata.

2.5 STABILIZATION OF MARINE CLAYS Soil stabilization is a procedure where natural or manufactured additives or binders are used to improve the properties of soils. Chemical additives, such as lime, cement, Saw dust, and other chemical compounds have been used in marine clays stabilization for many years with various degrees of success.

The clay minerals have the property of absorbing certain anions and cautions and retaining them in an exchangeable state. The exchangeable ions are held around the outside of the silica-alumina clay mineral structural unit. Compositional variation through ionic or isomorphous substitution within the clay mineral crystal lattice can leave the structural unit with a net


negative charge. Substitution also reduces the crystal size and alters its shape. Exposed hydroxyl groups and broken surface bonds can also lead to a net negative charge on the structural unit. The presence of this net negative charge means that soluble cautions can be attracted or adsorbed on to the surface of the clay mineral structural units without altering the basic structure of the clay mineral. The ability of clay to hold cautions is termed its caution exchange capacity. The most common soluble cautions are Na+, K+, Ca2+, Mg2+, H+, and NH4+. Caution exchange capacity (C.E.C.) has major significance in determining clay mineral properties, particularly the facility with which they absorb water. Caution exchange capacity (C.E.C.) measures two of the fundamental properties of clays: 1. The surface area and the charge on this surface area. 2. The surface of clay can be of two sorts; external and internal (Figure 1.9). The external exchange capacity measures nothing more than the average crystalline size. The surface capacity of adsorption is largely dependent upon broken bonds and surface growth defects. Surface and Absorbed Ion Interlayer Sites. The internal exchange capacity is much more interesting in that it reflects the overall charge imbalance on the layer structure and the absorption capacity of the clays. The exchange capacity is an estimate of both the number of ions adsorbed between the layers of a clay structure and of those adsorbed on the outer surfaces. C.E.C., measured in terms of milli equivalent of the atomic weight of solvent/100 gram of the dry solid, varies widely for various types of clay minerals The exchange capacity is almost always measured as a function of the number of cautions (positively charged) which can be measured on the clay surface once it is washed free of exchange salt solution. The operation is performed by immersing a quantity of clay in an aqueous solution containing a salt, usually chloride or ammonium hydroxide. The soluble ions adsorbed with the water onto the interlayer structure can affect the adsorbed water arrangement in several ways. Principally, they act as a bond of varying


strength holding the structural layer together and controlling the thickness of adsorbed water. Their effectiveness will depend on the size and charge. Thus Na+, K+ will tend to be weak and a clay-water system containing these ions will be capable of adsorbing large amounts of water. Ca2+, Mg2+, on the other hand, will have stronger links and a clay-water system containing them will possess substantially lower water content. Inclusion of Fe3+ or Al3+ would reduce the water content and plasticity and this is in fact the basis of the electro-chemical or electro-osmotic method of clay stabilization 2.6 SAW DUST

Wood cutting factories, generates a by-product known as Saw dust. This surrounds the Forestry area. During cutting of trees about78% of weight is received from trees. Rest 22% of the weight of trees is received as dust. This dust is used as fuel in burning of bricks & generate steam for the parboiling process.


Fig.2.2 Saw Dust

As transportation system expand, they are more likely to be supported by less desirable foundation soils, such as highly compressible deposits. The mass of the earthwork for such systems can cause unacceptable long –term settlement or even shear failure of these deposits. Ground improvement techniques may not be effective in stabilizing such soils. Although not a composite, geofoam provides a very lightweight manufactured fill for embankments on such materials. The development of light weight fill has led to engineering of fills consisting of soil-like particulate materials that are lighter than soil, not prohibitively expensive, and environmentally safe. Saw dust and lime are excellent examples of such materials.

TABLE 2.1 CHEMICAL COMPOSITION OF SAW DUST

SiO2 86 %


Al2O3 2.6%

Fe2O3 1.8%

CaO 3.6%

MgO 0.27%

Loss in ignition 4.2%

TABLE 2.2 PHYSICAL PROPERTIES OF SAW DUST

S. No PROPERTY VALUE

1 Grain size distribution

(percent finer than)

4.75 mm 100

2.0 mm 96

0.6 mm 80

0.425 mm 50

0.21 mm 29

0.075 mm 8

2 SPECIFIC GRAVITY 2.01

2.6.1 USES OF SAW DUST

As a stabilizer

The Saw Dust would appear to be an inert material with the silica in the crystalline form suggested by the structure of the particles, it is very unlikely that it would react with lime to form calcium silicates. It is also unlikely that it would be as reactive as fly ash, which is more finely divided. So saw dust would give great results when it used as a stabilizing material.

In lightweight fill


The ash would appear to be a very suitable light weight fill and should not present great difficulties in compaction, provided its initial moisture content is kept within reasonable limits (say less than 50%). The very high angle of internal friction of the material will mean that its stability will be high. However, its lack of cohesion may lead to problems in construction due to erosion and shearing under heavy rollers. To overcome these it will probably be desirable to place a 3 to 6 inch thick blanket layer of cohesive material every 2 to 3 ft.

Other uses On an Industry, wide basis most saw dust is green. Green saw dust has

limited uses, for examples, as fuel at the producing plant or pulping. Green hard wood saw dust is also used in fairly large amounts for meat smoking.

In some localities green soft wood saw dust furnace for domestic heating. Thus far it has seldom been considered economically feasible to dry saw dust artificially.

Brief information on various uses of sawdust and shavings is tabulated in tables 1, 2, 3, and 4 of this report.

Under four general classifications 1. Uses based on special physical qualities.2. Fuel uses.3. Fibre and wood base board uses.4. Chemical Uses.

2.7 Summary In this chapter the experience of the various researchers in the field of marine clays and Saw dust were presented.

In the next chapter details of laboratory experimentation carried out will be discussed.

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CHAPTER IIISTUDY METHODOLOGY

3.1 VARIABLES TAKEN FOR THE STUDY

The study is carried out on BC soil +Saw Dust and BC soil were varied in the following percentages.

Saw Dust in percentages of 10%, 20%, 30% and 40% by Weight of BC soil.

3.2 MATERIAL USED

3.2.1 Marine Clay

The soil used in this study is BC soil, obtained from NIT Campus, Collected at a depth of 1.5m from ground level. The Index & Engineering properties of BC soil are determined as per IS code of practice and determined.

3.2.2 Saw Dust

Locally available Saw Dust was used in the present work. The physical properties are determined.

3.3 LABORATORY STUDIES

The laboratory studies were carried out on the samples of BC soil, BC soil + Saw Dust.

3.3.1 Liquid limit

Liquid limit test was conducted on BC soil, BCsoil+20% Saw Dust using Casagrande’s liquid limit apparatus as per the procedures laid down in IS: 2720 part 4 (1970).

3.3.2 Plastic limit


Plastic limit test was conducted on BC soil, BCsoil+20% Saw Dust as per the specifications laid down in IS: 2720 part 4 (1970). 3.3.3 Shrinkage limit

This test is also conducted on to BC soil, BCsoil+20% Saw Dust as per IS: 2720 part 4 (1972).3.3.4 Free swell index

This test is performed by pouring slowly 10 gms of dry soil, 10 gms of (soil+ Saw Dust) passing through 425 micron sieve, in two different 100 cc glass jar filled with distilled water. The swollen volume of BC soil, BC soil- Saw Dust are recorded as per IS 2720 part 40 (1985).

Final volume – Initial volume Free swell (%) = --------------------------------------- *100 Initial volume

3.3.5 Proctor’s standard compaction Test

Preparation of soil sample for proctor’s compaction test was done as per IS: 2720 part-6 (1974).

3.3.6 Unconfined compressive strength

The unconfined compressive strength tests are conducted on BC soil, BC soil+ Saw Dust mixture as per IS 2720 part 10 (1973). All the samples are prepared by static compaction using split mould at Optimum moisture content and Maximum dry density to maintain same initial dry density and water content. The test was conducted under a constant strain rate of 1.5mm/min. The proving ring reading is noted for 50 divisions, and loading was continued until 3 (or) more reading are decreasing (or) constant (or) strain 20% has been reach. The samples of BC soil –additive mixes were cured 4 days, 7days and 28days curing period and at the end of each curing period the samples were tested. Three samples for each mix were tested.


3.3.7 California bearing ratio Test

The California bearing ratio tests are conducted on BC soil, BC soil+ Saw Dust, BC soil+ Saw Dust mixtures as per IS 2720 part 16 (1979). The test was conducted under a constant strain rate of 1.25mm/min. The proving ring reading is noted for 50 divisions, and loading was continued until 3 (or) more readings are decreasing (or) constant. The test was conducted at Optimum moisture content. The samples were tested in soaked condition. The tests were conducted at time interval of curing for 4 days, 7days and 14 days.

3.3.8. General

The soil was initially air dried prior to the testing. The tests were conducted in the laboratory on the marine clay to study the behaviour of marine clay, when it was untreated, treated (with chemicals, Saw Dust and reinforcement techniques) for the modal flexible pavements and also for the foundation soil beds.The following tests were conducted as per IS Codes of practice.

i. The grain size distribution ii. Index properties –Liquid Limit, Plastic Limit, Shrinkage Limit

iii. Swell Tests- Differential Free swell, Swell Pressureiv. Strength tests- California bearing ratio

3.3.9. Visual characteristics

The following properties were observed from visual classification in dry condition.

Colour -- Black colour Odour -- Odour of decaying vegetationTexture -- Fine grainedDry strength -- medium Dylatancy -- Less SluggishPlasticity --Highly plasticClassification -- Highly Compressible Clay (CH)


Table No: 3.1 Physical properties of marine clay

SL.No Property Symbol Value

1 Gravel 0 %

2 Sand 14%

3 Fines

Silt 30%

Clay 56%

4 Liquid Limit WL 74.5 %

5 Plastic Limit WP 26.9 %

6 Plastic Index IP 47.6 %

7 Shrinkage limit ws 10.678 %

8 Soil Classification CH

9 Specific Gravity G 2.35

10 Differential Free Swell

80%

11 Optimum Moisture Content

O.M.C. 35%

12 Maximum Dry Density M.D.D. 1.27 gm / cc

13 Cohesion C 12 .20 t /m2

14 Angle of Internal Friction

20

15 CBR Value ( soaked) 0.754 %

16 NMC 86.15%


3.4 Laboratory Testing

3.4.1Grain Size Analysis (Sieve Analysis) The weight of soil fraction aggregate retained on each standard sieve is

calculated as the percentage of the total weight of the sample taken. The grain size distribution of soils/aggregates is an essential requisite in material characterization. Indian standard codes of practice I.S:1498-1970.

Dry sieve analysis is suitable for cohesion less soils and if the soil contains a substantial quantity of fine particles, a wet sieve analysis is required.

3.4.2 Water contentThe water content is defined as the ratio of the mass of water to

the mass of solids. The water content is also known as the moisture content. It is expressed as percentage and used as decimal in computation.

The water content of a soil is an important parameter that controls its behaviour. It is a quantitative measure of the wetness of a soil mass. The water content of a soil can be determined by many methods of which oven drying method has been adopted. In this method the soil sample in the container is dried in an oven at a temperature of 110°±5°C for 24 hours.

Water content, w= Mw/ Ms = (M2-M3)/ (M3-M1)Where M1 = mass of container, with lid

M2 = mass of container, lid and wet soil M3 = mass of container, lid and dry soil

3.4.3Consistency Limits & Indices The physical properties of fine grained soils, especially of clay differ

much at different water contents. Clay may be almost in a liquid state, or it may show plastic behaviours or may be very stiff depending on the moisture


content. Plasticity is a property of clayey soils, which may be explained as the ability to undergo changes in shape without rupture. Indian Standard codes of practice I.S: 2720 (Part V) – 1985: I.S: 2720 (Part VI)-1972).

Identification and Classification of Soils:

Liquid Limit and Plasticity Index are two of the important properties for the identification and classification of fine grained soils. Classification of silty and clayey soils by the HRB and Unified soils classification systems are based on Liquid Limit and Plasticity Index.

Compressibility: The Liquid Limit of clay indicates its compressibility. Higher the liquid

limit, higher is the compressibility. The compression index of normally consolidated clay is found to be dependent on the liquid limit.

3.4.3.1 Liquid Limit TestLiquid limit is the water content at which the soil changes from the

liquid state to the plastic state. At the liquid limit, the clay is practically like a liquid, but possesses a small shearing strength. The shearing strength at that stage is the smallest value that can be measured in the laboratory.

Liquid limit is the moisture content at which 25 blows in standard liquid limit apparatus will just close a groove of standard dimensions cut in the sample by the grooving tool by a specified amount. The flow curve is plotted in the log-scale on the x-axis, and the water content in the arithmetic scale on the y-axis. The flow curve is straight line drawn on this semi-logarithmic plot, a nearly as possible through three or more plotted points. The moisture content corresponding to 25 blows is read from this curve rounded off to the nearest whole number and is reported as the liquid limit of the soil.

3.4.3.2 Plastic Limit

Plastic limit is the moisture content at which a soil when rolled into thread of smallest diameter possible, starts crumbling and has a diameter of 3 mm.


The Plastic Limit (wp) is expressed as a whole number by obtaining the mean of the moisture contents of the plastic limit. Plasticity Index (P.I) is calculated as the difference between liquid limit and plastic limit. This gives an idea about the clay content in a soil. Plasticity Index increases with clay content.

Plasticity Index = liquid limit – plastic limit

Ip = Wl - Wp

3.4.3.3 Shrinkage Limit

Shrinkage Limit is the maximum water content at which a reduction in water content will not cause a decrease in volume of the soil. It is also the minimum moisture content to keep a soil saturated without increase in volume.

This gives an idea about the shrinkage or swelling which is likely to take place after being compacted at specified moisture content. If a soil is compacted at its OMC which happens to be higher than its shrinkage limit (as in heavy clays) the compacted soil mass will shrink on drying after compaction.

Moisture content of the soil paste taken in the shrinkage dish is calculated.

w%=[ w1−w2w2−w3 ] x100 percentWhere w1,w2 and w3 are respectively the weights of dish plus wet soil,

dish plus dry soil and dish only.

Shrinkage limit ws is calculated from the relation w s=w−(

v−v0w0

)x 100

Where, w = moisture content of paste forming wet pat, %v = volume of wet pat , cm3

w0 = weight of oven dry pat = (w2-w3) gmShrinkage ratio, R is given by R = w0/v0


3.4.3 Compaction Test

Fig 3.1 Author Doing Compaction Test

From the compaction test, the maximum dry density (MDD) and Optimum Moisture Content (OMC) of the soil are found for the selected type and amount of compaction. Indian standard codes of practice I.S:2720 (Part VIII – 1983). The weight of mould with moist compacted soil is W gm.

Weight of empty mould = Wm gmVolume of mould = Vm cc

Wet density, γm=

w−wmvm

g/ccLet the moisture content be = w%

Then dry density,

γd=γm

(1+ w100 )

=(w−wm)

vm(1+ w100 )

g/cc

The OMC of the soil indicated the particular moisture content at which the soil should be compacted to achieve maximum dry density. If the compacting


effort applied is less, the OMC increases and the value can again be found experimentally or estimated.

In field compaction, the compacting moisture content is first controlled at OMC and the adequacy of rolling or compaction is controlled by checking the dry density achieved and comparing with the maximum dry density. Thus compaction test results (OMC and maximum dry density) are used in the field control test in the compaction projects.

Compaction, in general in considered most useful in the preparation of sub grade and other pavement layers and in construction of embankments in order to increase the stability and to decrease settlement. There is also a soil classification method based on the maximum dry density in the standard (proctor compaction test lower values indicating weaker soil.

3.4.4 California Bearing Ratio Test (CBR) The CBR is a measure of shearing resistance of the material under

controlled density and moisture conditions. The load-penetration curve for each specimen is plotted on natural scale. The load values at 2.5 mm and 5.0 mm are obtained from the load penetration curve to compute CBR values using the following equation.

CBR(%) = Load carried by soil sample at defined penetration level * 100 Load carried by standard crushed stones at the above penetration levelBased on extensive CBR test data collected, empirical design charts

were developed by the California State Highway Department, correlating the CBR value and flexible pavement thickness requirement. For various traffic volumes different design thickness curves are available.

3.4.5 Tri-axial Test

Shear tests are generally carried out on small samples in the laboratory to evaluate the strength properties of the element in the soil mass. The


strength parameters, namely the cohesion and angle of shearing resistance are usually found from these tests.

The tri axial test specimen is subjected to the all round pressure equal to the lateral pressure, σ3 and the applied vertical stress or deviator stress σd

such that the total vertical stress is σ1 = σd + σ3. Mohr stress circles are plotted at normal stress intercepts σ3 and σ1 or with diameters equal to deviator stresses. From the Mohr’s envelope, the cohesion C and the angle of internal friction φ of the soil can be derived.

The shear strength parameters C and φ of the materials may be used to find the shearing resistance of the material, using Coulomb’s equation.

S = C + σ tan

In flexible pavement design, the E value of sub grade soils is to be found from triaxial test.

Triaxial test is used in the design of bituminous mixes.

3.4.6 Specific Gravity Test

Specific gravity of solid particles (G) is defined as the ratio of the mass of a given volume of solids to the mass of an equal volume of water at 4°C.

The specific gravity of solid particles can be determined in a laboratory using a density bottle fitted with a stopper. The mass of bottle, including that of stopper, is taken. About 5-10g of oven dry sample of soil is taken in bottle and weighed. Distilled water is then added to cover the sample. The soil is allowed to soak. More water is added until the bottle is half full. Air entrapped in the soil is expelled by applying a vacuum pressure in vacuum desiccators. More water is added to the bottle to make it full. The stopper is inserted and the mass is taken. The bottle is emptied, washed and then refilled with distilled water. The bottle must be filled to the same mark as in the previous case. The mass of water filled with water is taken. G = (M2-M1)/ [(M2-M1) – (M3-M4)]

Where


M1=Mass of Empty bottleM2=Mass of bottle and dry soilM3=Mass of bottle, soil and waterM4=Mass of bottle filled with water

3.4.7 Differential Free Swell Test Differential Free Swell (DFS) is a parameter used for the identification of the expansive soil.

For the determination of the differential free swell of a soil, 20g of dry soil passing through a 425µ size sieve is taken. One sample of 10g is poured into a 100c.c capacity graduated cylinder containing water, and the other sample of 10g is poured into a 100c.c capacity graduated cylinder containing kerosene oil.

Both the cylinders are kept undisturbed in a laboratory. After 24 hours, the settled volumes of both the samples are measured

DFS= (Settled soil volume in water – settled soil volume in kerosene)*100 Settled soil volume in kerosene

Because kerosene is a non-polar liquid, it does not cause any swell of the soilIS: 2720 (Part III- 1980) gives degree of expansion of a soil depending upon its differential free swell as under Table 3.4.8Differential Free Swell

S. No. Degree of expansion DFS1 Low < 20%2 Moderate 20 - 35%3 High 35 – 50%4 Very High >50%


3.4.9 PHYSICAL PROPERTIES OF SAW DUST

Table no 3.2 Physical Properties of Saw dust

Sl.no

Properties Saw dust

1 Grain size distributionGravel(%)Sand(%)Silt size(%)Clay size(%)

…….257005

2 Atterberg limitsLiquid limit(%)Plastic limit(%)Plasticity indexShrinkage limit(%)

74.526.947.610.678

3 Compaction propertiesOptimum moisture content(%)Maximum dry density(g/cc)

20.71.35

4 Un-soaked CBR(%)Soaked CBR(%)

5.53.15

5 Specific gravity 2.106 Free swell index 807 Cohesion C (KN/m2)

Angle of internal friction831

8 Soil classification ML


CHAPTER IVPRESENTATION AND DISCUSSIONS ON RESULTS

1. PROPERTIES OF MARINE 2. M.C+SAW DUST

4.1 General

Details of the laboratory experimentation carried out with different combinations of materials have been discussed in the previous chapter. In this chapter a detailed discussion on the results obtained from various laboratory tests are presented.

4.2 LABORATORY TEST RESULTS

To find the optimum percentage of Saw Dust with marine clay and optimum percent of CaCl2 to the combination of marine clay and Saw dust, CBR tests are conducted by using different proportions of soil- Saw dust and soil – Saw dust -CaCl2 4.2.1 Proctor Compaction and CBR test results for Soil and Saw Dust

4.2.1.1 Proctor compaction test results Many tests were conducted to get the OMC and MDD of the mix of

different proportions of soil and Saw Dust using standard proctor compaction machine.

(a)75%+25%

Table 4.2.1.1 Moisture content and dry density of only soil

Sl. No Water Content (%) Dry Density (g/cc)1. 39.49 1.0382. 48.63 0.9923. 50.46 0.954


30 35 40 45 50 550.9

0.92

0.94

0.96

0.98

1

1.02

1.04

1.06

1.038

0.992

0.954000000000001

Water content(%)

Dry

dens

ity(g

/cc)

Optimum Moisture Content =39.49%

Maximum Dry Density = 1.038

(b)80%+20%

Sl. No

Water Content (%) Dry Density (g/cc)

1. 35.43 1.082. 44.92 1.0783. 56.46 0.971

30 35 40 45 50 55 600.9

0.920.940.960.98

11.021.041.061.08

1.11.08 1.078

0.971000000000001

Water content(%)

Dry

dens

ity(g

/cc)



Maximum Dry Density = 1.1.08gm/cc

(c)85%+15%

Sl. No

Water Content (%)

Dry Density (g/cc)

1. 24.06 1.1272. 29.63 1.2633. 84.77 0.865

20 30 40 50 60 70 80 90 1000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.1271.263

0.865000000000002

Water content(%)

Dry

dens

ity(g

/cc)


Maximum Dry Density = 1.263gm/cc

(d)90%+10%


30 35 40 45 50 55 601

1.05

1.1

1.15

1.2

1.25

1.1921.181

1.072

Water content(%)

Dry

dens

ity(g

/cc)


Maximum Dry Density = 1.192gm/cc

(e)95%+5%

Sl. No

Water Content (%)

Dry Density (g/cc)

1. 38.33 1.1922. 44.92 1.1813. 49.13 1.072

Sl. No

Water Content (%)

Dry Density (g/cc)

1. 38.36 1.2282. 44.48 1.2723. 49.64 1.161


30 35 40 45 50 55 601.1

1.121.141.161.18

1.21.221.241.261.28

1.3

1.228

1.272

1.161

Water content(%)

Dry

dens

ity(g

/cc)


Maximum Dry Density = 1.272

Table 4.2.1.2 Optimum moisture content and maximum dry density values of marine clays and saw dust

Mix proportion Water Content (%) Dry Density (g/cc)75%soil+25%SD

39.49 1.038

80%soil+20%SD

35.43 1.08

85%soil+15%SD

29.63 1.263

90%soil+10%SD

38.33 1.192

95%soil+5%SD 44.48 1.272


0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

5

10

15

20

25

30

35

40

45

50

29.63

35.43

44.48

39.49 38.33

variation of mdd with Saw dust

water content (%)

max

dry

den

sity(

g/cc

)

4.3 CBR TEST RESULTS : The soaked CBR values of various mixes of marine clay and Saw dust using OMC obtained from compaction are determined. The soaked CBR after immersing in water for four days , that is when full saturation is likely to occur, is also determined. Variation of CBR with % variation in Saw Dust is presented.

75%MARINE CLAY+25% Saw Dust

0 2 4 6 8 10 12 140

5

10

15

20

25

30

Soaked

Penetration(mm)

Load(kg)


80%MARINE CLAY+20%Saw Dust

0 2 4 6 8 10 12 140

2

4

6

8

10

12

14

16

18

Soaked

Penetration(mm)

Load(kg)


0 2 4 6 8 10 12 140

10

20

30

40

50

60

70

80

90

Soaked

Penetration(mm)

Load(kg)



0 2 4 6 8 10 12 140

10

20

30

40

50

60

Soaked

Penetration(mm)

Load(kg)


0 2 4 6 8 10 12 140

5

10

15

20

25

30

Soaked

Penetration(mm)

Load(kg)

Mix proportion Water Content (%)

Soaked CBR

85%soil+15%SD 29.63 4.0380%soil+20%SD 35.43 0.67295%soil+5%SD 44.48 0.896

75%soil+25%SD 39.49 0.89690%soil+10%SD 38.33 2.24


0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

5

10

15

20

25

30

35

40

45

50

29.63

35.43

44.48

39.49 38.33

variation of soaked CBR with Saw Dust

Saw dust %

soak

ed C

BR(%

)

Table 4.9 Properties of the stabilized soil with an optimum of Saw dust

N o. Property Symbol Value

1 Liquid Limit WL

2 Plastic Limit WP

3 Plastic Index IP

4 Shrinkage limit Ws

5 Soil Classification CH

6 Specific Gravity G

7 Differential free swell


8 Optimum Moisture Content

O.M.C.

9 Maximum Dry Density M.D.D.

10 Cohesion C

11 Angle of Internal Friction

12 CBR Value ( soaked)

4.4 Summary

The laboratory test results have been discussed in this chapter. The summary of work done and scope of further work will be presented in the next chapter.


CHAPTER-5

CONCLUSIONS

5.1. General In this chapter the summary of the work carried out is presented along with conclusions drawn from the study. The scope for further research in this area is also suggested at the end.

5.2. Conclusions

The following conclusions are drawn based on the laboratory test results.

It is noticed that the liquid limit of the marine clay has been decreased by about 11.00% with the addition of 20% saw dust as an optimum. Further it is observed that the liquid limit of marine clay has been decreased by 9% on addition of saw dust.

It is observed from the results that the Plasticity index of the marine clay has been decreased by about 24.00% on addition of saw dust.

It is found from the results that the M.D.D of the marine clay has been increased by about by 12.36% on addition of saw dust

It is observed from the results that the C.B.R. value of the marine clay has been increased by ------% on addition of saw dust

It is observed from the results that the DFS value of the marine clay has been decreased by 58% on addition of saw dust

The soaked CBR of the soil on stabilizing is found to be 6.48% and is satisfying standard specifications. So finally it is concluded from the above


results that the stabilized marine clay is suitable to use as sub grade material for the pavement construction

5.3 Further Scope of Work

The following areas are identified as those having scope for further research

1. Similar work can be done using other additives and also admixtures to arrive the optimum combination used in construction of pavements on marine clay soil sub grades.

2. The reinforcement Technique can be adopted for higher load carrying capacity of the pavement sub grades.

The following conclusions are drawn on the basis of test results obtained on BC soil stabilized with Saw Dust.

1. The liquid limit of BC soil is decreases at 20% Saw Dust.

2. The Free Swell Index of BC soil is reducing moderately at 20% Saw

Dust.

3. There is considerable increase in the values of unconfined compressive

strength of BC soil mixed with 20% Saw Dust. The gain in strength in

early days is due to the development of cementation action between

clay, Saw Dust.

4. The CBR value increased considerably at 14 days saturation compared

to 4 and 7 days.


5. Addition of small percentage of Gypsum reduces the hardening process,

helped to further development of pozzolanic action in Unsoaked and

soaked condition. Its effect is more in soaked condition.

6. It is observed that there is remarkable influence on strength and CBR

values of expansive soil at 20% Saw Dust which is a optimum

percentage.

7. Saw Dust can potentially stabilize the expansive soil solely.

8. The utilization of industrial wastes like Saw Dust is an alternative to

reduce the construction cost of roads particularly in the rural areas of

developing countries.


BIBLIOGRAPHY/REFERENCES

1. Ganapathy, 1977; Jones and Jones, 1995; Abduljauwad, 1995; Osama and Ahmed, 2002; Zhan, 2007)

2. Agarwala, V.S and Khanna, J.S (1969), Construction techniques for foundations of buildings on black cotton soils, proceedings of the symposium on characteristics and construction techniques in black cotton soil, the college of military Engg., Poona, India.

3. Al Quadi, I.L (1994), Laboratory Evaluation of Geosynthetics Reinforced Pavement Sections, TRR-1739, TRB, 1994, pp. 25-31.

4. Al-Omari, R.R and Oraibi, W.K (2000), Cyclic behavior of reinforced expansive clay, Jr. of the Japanese Geotechnical Society of Soils and Foundations, Vol. 40, No. 2; 2000, pp.1-8.

5. Al-Rawas, N.M (2000), Effect of curing and temperature on lime stabilization, Proc. Of Second Australian Conf. on Engineering Materials, Sydney, 1981, pp.611-662.

6. Ambily, A.P and Gandhi, S.R (2004), Experimental and Theoretical Evaluation of Stone Column in Soft Clay, ICGGE, pp 201-206.


7. Anand J.Puppala, Ekarin Wattanasanticharoen and Laureano R.Hoyos (2003), Ranking of Four Chemical and Mechanical Stabilization Methods to Treat Low-Volume Road Subgrades in Texas, Jr.-Transportation Research Record, Vol. 1819B, 2003, pp. 63-71.

8. Anandarajah. A and Chu. J (1997), Laboratory Determination of shear strength parameters for marine clay, Journal of the Institution of Engineers, Singapore, Vol.14, No.3, pp 39-46.

9. Arvind Kumar, Baljit Singh Walia and Asheet Bajaj (2007), Influence of Flyash, Lime and Polyester Fibers on Compaction and Strength Properties of Expansive Soil, J.Mat in Civil Engineering, ASCE, Vol. 19, Issue. 3, 2007, pp. 242-248.

10.Balasubramaniam, A.S., Bergado, D.T., Buensuceso, B.R. and Yang, W.C (1989), Strength and deformation characteristics of lime treated soft clays, Geotechnical Engineering (AIT), 20, 1989, pp. 49-65.

11.Bansal, R.K., Pandey, P.K. and Singh, S.K (1996), Improvement of a Typical Clay for Road Subgrades with Hydrated Lime, Proc. Of National Conf. on Problematic Subsoil Conditions, Terzaghi-96, Kakinada, India, 1996, pp. 193-197.

12.Chandrashekar, B.P., Prasada Raju, G.V.R (1999), Relative Performance of Lime and Calcium Chloride on Properties of Expansive Soil For Pavement Subgrades, Proc. Of IGC-99, Calcutta, 1999, pp 279-282.

13.Heaton, B.S (2001), presented the utilization of waste products from Steel plants in the pavements. Australia Civil Engineering Transaction, IE Aust., Vol. CE35, No.1.

14. I.S: 2720, Part VII, (1980), Determination of Water Content Dry Density Relation Using Light Compaction.

15. I.S: 2720-Part III, Section I, 1980, Determination Specific Gravity.16. I.S: 2720-Part IV, 1975, Determination of Grain Size Distribution.17. I.S:2720, Part VI, 1972, Determination of Shrinkage Factors.18. I.S;2720-Part V, 1970, Determination of Liquid Limit and Plastic

Limit.


19. CIRIA Publication (2002); BS EN 15237 (2007); TRL Projects Reports PPR 341(2008), represented the advantages of using the band drain in soft soils.

CHAPTER V

CONCLUSIONS

CHAPTER VI

REFERENCES

raju-marine clay with saw dust final

Documents

indian standard

differential

maximum dry

bc soil

soft soils

sieve analysis

dry density

soft clay