compaction seminar report

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Chapter 1:

Chapter 1:

INTRODUCTION

INTRODUCTION

Soil compaction is the process to increase the soil (ground) density in order to make use Soil compaction is the process to increase the soil (ground) density in order to make use the ground surface for development, i.e. building, road, etc. The volume of void space is the ground surface for development, i.e. building, road, etc. The volume of void space is reduced by applying high loads over a small area to force the air out of an unsaturated soil reduced by applying high loads over a small area to force the air out of an unsaturated soil mass. What happens to air spaces when someone steps on the soil or a piece of equipment mass. What happens to air spaces when someone steps on the soil or a piece of equipment drivesover the

drivesover the soil? soil? The soil The soil compacts again.compacts again. In

In Geotechnical engineering, Geotechnical engineering, soil compaction is the process in which a stress applied to a soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains.The soil causes densification as air is displaced from the pores between the soil grains.The soils at the given site are often less than ideal for the intended purpose. They may be soils at the given site are often less than ideal for the intended purpose. They may be weak/highly compressible or have a higher permeability than desirable from the weak/highly compressible or have a higher permeability than desirable from the geotechnical engineering point of view. In such situations, one has to try to stabilize or geotechnical engineering point of view. In such situations, one has to try to stabilize or improve the engineering properties of such soils. This can be achieved through improve the engineering properties of such soils. This can be achieved through compaction [1].

compaction [1].

The better the compaction, the better will be shear strength, density and bearing capacity The better the compaction, the better will be shear strength, density and bearing capacity of the individual layers and with that the lasting quality of the embankment of road of the individual layers and with that the lasting quality of the embankment of road construction

construction.Rollers are used for compaction since long olden days. Over a thousand.Rollers are used for compaction since long olden days. Over a thousand

years ago the Chinese used huge cylindrical shaped stone rollers for road works, and the

years ago the Chinese used huge cylindrical shaped stone rollers for road works, and the

world famous builders of Rome used towed stone rollers. The self propelled road rollers

world famous builders of Rome used towed stone rollers. The self propelled road rollers

 powered by steam engines were

 powered by steam engines were built in 19built in 19thth century .As the time passed the development century .As the time passed the development

of compaction equipments has taken place rapidly[2].

of compaction equipments has taken place rapidly[2].

Soil compaction is one of the most critical components in the construction of roads, Soil compaction is one of the most critical components in the construction of roads, airfields, embankments, and foundations. The durability and stability of a structure are airfields, embankments, and foundations. The durability and stability of a structure are related to the achievement of proper soil compaction. Structural failure of roads and related to the achievement of proper soil compaction. Structural failure of roads and airfields and the damage caused by foundation settlement can often be traced back to the airfields and the damage caused by foundation settlement can often be traced back to the

failure to achieve proper soil compaction

failure to achieve proper soil compaction

. It is a standard procedure in the construction. It is a standard procedure in the construction of earth structures, such as embankments, subgrades, and bases for road and airfield of earth structures, such as embankments, subgrades, and bases for road and airfield  pavements.

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1.1 Soil Compaction

1.1 Soil Compaction

Soil compaction is defined as the method of mechanically increasing the density of soil. Soil compaction is defined as the method of mechanically increasing the density of soil. In construction, this is a significant part of the building process. If performed improperly, In construction, this is a significant part of the building process. If performed improperly, settlement of the soil could occur and result in unnecessary maintenance costs or structure settlement of the soil could occur and result in unnecessary maintenance costs or structure failure. Almost all types of building sites and construction projects utilize mechanical failure. Almost all types of building sites and construction projects utilize mechanical compaction techniques.

compaction techniques.

Compaction involves an expulsion of air without a significant change in the amount of Compaction involves an expulsion of air without a significant change in the amount of water in the soil mass. Thus, the moisture content of the soil, which is defined as the ratio water in the soil mass. Thus, the moisture content of the soil, which is defined as the ratio of the Weight of water to the weight of dry soil particles, is normally the same for loose, of the Weight of water to the weight of dry soil particles, is normally the same for loose, un compacted soil as for the same soil after compaction. Since the amount of air is un compacted soil as for the same soil after compaction. Since the amount of air is reduced without change in the amount of water in the soil mass, the degree of saturation reduced without change in the amount of water in the soil mass, the degree of saturation (the ratio of the volume of water to the combined volume of air and water) increases. (the ratio of the volume of water to the combined volume of air and water) increases. When used as a construction material, the significant engineering properties of Soils are When used as a construction material, the significant engineering properties of Soils are its shear strength, its compressibility, and its permeability. Compaction of the soil its shear strength, its compressibility, and its permeability. Compaction of the soil generally increases its shear strength, decreases its compressibility, and decreases its generally increases its shear strength, decreases its compressibility, and decreases its  permeability [3].

 permeability [3].

1.2 Why compact?

1.2 Why compact?

There are five principle reasons to compact soil: There are five principle reasons to compact soil:

1.

1. Increases load-bearing capacityIncreases load-bearing capacity 2.

2. Prevents soil settlement and frost damagePrevents soil settlement and frost damage 3.

3. Provides stabilityProvides stability 4.

4. Reduces water seepage, swelling and contractionReduces water seepage, swelling and contraction 5.

5. Reduces settling of soilReduces settling of soil

We compact (densify) fine grained soils so they absorb less free moisture. Soil tends to We compact (densify) fine grained soils so they absorb less free moisture. Soil tends to absorb moisture with time and softens, promoting bearing and to reduce differential absorb moisture with time and softens, promoting bearing and to reduce differential settlement. We also compact soil and rock mixtures to

settlement. We also compact soil and rock mixtures to increaseincrease their effective sheartheir effective shear strength, making them more able to resist gross deformations .Excessive settlement may strength, making them more able to resist gross deformations .Excessive settlement may eventually lead to complete slope failure hencewe compact soils to reduce the long-term eventually lead to complete slope failure hencewe compact soils to reduce the long-term settlement

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1.1 Soil Compaction

1.1 Soil Compaction

Soil compaction is defined as the method of mechanically increasing the density of soil. Soil compaction is defined as the method of mechanically increasing the density of soil. In construction, this is a significant part of the building process. If performed improperly, In construction, this is a significant part of the building process. If performed improperly, settlement of the soil could occur and result in unnecessary maintenance costs or structure settlement of the soil could occur and result in unnecessary maintenance costs or structure failure. Almost all types of building sites and construction projects utilize mechanical failure. Almost all types of building sites and construction projects utilize mechanical compaction techniques.

compaction techniques.

Compaction involves an expulsion of air without a significant change in the amount of Compaction involves an expulsion of air without a significant change in the amount of water in the soil mass. Thus, the moisture content of the soil, which is defined as the ratio water in the soil mass. Thus, the moisture content of the soil, which is defined as the ratio of the Weight of water to the weight of dry soil particles, is normally the same for loose, of the Weight of water to the weight of dry soil particles, is normally the same for loose, un compacted soil as for the same soil after compaction. Since the amount of air is un compacted soil as for the same soil after compaction. Since the amount of air is reduced without change in the amount of water in the soil mass, the degree of saturation reduced without change in the amount of water in the soil mass, the degree of saturation (the ratio of the volume of water to the combined volume of air and water) increases. (the ratio of the volume of water to the combined volume of air and water) increases. When used as a construction material, the significant engineering properties of Soils are When used as a construction material, the significant engineering properties of Soils are its shear strength, its compressibility, and its permeability. Compaction of the soil its shear strength, its compressibility, and its permeability. Compaction of the soil generally increases its shear strength, decreases its compressibility, and decreases its generally increases its shear strength, decreases its compressibility, and decreases its  permeability [3].

 permeability [3].

1.2 Why compact?

1.2 Why compact?

There are five principle reasons to compact soil: There are five principle reasons to compact soil:

1.

1. Increases load-bearing capacityIncreases load-bearing capacity 2.

2. Prevents soil settlement and frost damagePrevents soil settlement and frost damage 3.

3. Provides stabilityProvides stability 4.

4. Reduces water seepage, swelling and contractionReduces water seepage, swelling and contraction 5.

5. Reduces settling of soilReduces settling of soil

We compact (densify) fine grained soils so they absorb less free moisture. Soil tends to We compact (densify) fine grained soils so they absorb less free moisture. Soil tends to absorb moisture with time and softens, promoting bearing and to reduce differential absorb moisture with time and softens, promoting bearing and to reduce differential settlement. We also compact soil and rock mixtures to

settlement. We also compact soil and rock mixtures to increaseincrease their effective sheartheir effective shear strength, making them more able to resist gross deformations .Excessive settlement may strength, making them more able to resist gross deformations .Excessive settlement may eventually lead to complete slope failure hencewe compact soils to reduce the long-term eventually lead to complete slope failure hencewe compact soils to reduce the long-term

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Chapter 2:

Chapter 2:

EFFECTS OF POOR COMPACTION

EFFECTS OF POOR COMPACTION

Fig 1:

Fig 1: EFFECTS OF POOR COMPACTIONEFFECTS OF POOR COMPACTION In the slide above, you see six examples of structures t

In the slide above, you see six examples of structures t hat have been compromisedhat have been compromised  because of poorly compacted soil.

 because of poorly compacted soil.

In the first example, a structure has

In the first example, a structure has cracked due to the soil below it failicracked due to the soil below it failing due to lack ofng due to lack of compaction. In the second example, a concrete slab has cracked due to poor soil

compaction. In the second example, a concrete slab has cracked due to poor soil underneath it. The third example shows the joint in a pipeline which could separate

underneath it. The third example shows the joint in a pipeline which could separate due todue to  poor supporting so

 poor supporting soil. The fourth example shows a foundation cracking anil. The fourth example shows a foundation cracking and falling awayd falling away due to the soil settling. The fifth example shows a concrete block designed to support a due to the soil settling. The fifth example shows a concrete block designed to support a structure tipped to one side as the soil is not supporting it evenly. The last example shows structure tipped to one side as the soil is not supporting it evenly. The last example shows a trench settling, which jeopardizes the pipe that runs through it [4].

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Chapter 3:

SOIL TYPES AND CONDITIONS

Considering soil compaction, the two broad classifications are cohesive soils and cohesionless, or noncohesive, soils. Cohesive soils are those that contain sufficient quantities of silt or clay to render soil mass virtually impermeable when properly compacted. Such soils are all varieties of clays, silts, and silty or clayey sands and gravels. By contrast, cohesionless soils are the relatively clean sands and gravels, which remain pervious even when well-compacted [2].

Every soil type behaves differently with respect to maximum density and optimum moisture. Therefore, each soil type has its own unique requirements and controls both in the field and for testing purposes. Soil types are commonly classified by grain size, determined by passing the soil through a series of sieves to screen or separate the different grain sizes.

There are three basic soil groups: 1. Cohesive

2. Granular

3. Organic (this soil is not suitable for compaction and will not be discussed here).

Cohesive soil:

Cohesive soils have the smallest particles. Clay has a particle size range of .00004" to .002". Silt ranges from .0002" to .003". Clay is used in embankment fills and retaining  pond beds.

Granular soil:

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Organic soil:

These are partly decomposed vegetable matter. These make soil unsuitable for construction purposes, and needs to be removed and replaced with suitable soil.

Most soils are made up of a mixture of these basic soil types and are classified as sandy clay, clayey sand, sandy silt etc. Study of the properties of these types of soil greatly helps in selection of proper compaction equipment [6].

3.1 Soil Properties Affected By Compaction

Principal soil properties affected by compaction include-1. Settlement.

2. Shearing resistance. 3. Movement of water. 4. Volume change.

Compaction does not improve the desirable properties of all soils to the same degree. In certain cases, the engineer must carefully consider the effect of compaction on these the desire to hold volume change to a minimum may be more important than just an increase in shearing resistance.

Settlement:

  It is the decrease in surface elevation of the fill material within the embankment. A principal advantage resulting from the compaction of soils used in embankments is that it reduces settlement that might be caused by consolidation of the soil within the body of the embankment.

Shearing resistance

: It is the soils ability to resist slippage when a force is applied. Increasing density by compaction usually increases shearing resistance. This effect is highly desirable in that it may allow the use of a thinner pavement structure over a compacted subgrade.

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reduced. This change in voids has an obvious effect on the movement of water through the soil. One effect is to reduce the permeability, thus reducing the seepage of water.

Volume Change

:

Change in volume (shrinkage and swelling)is an important soil  property, which is critical when soils are used as subgrades for road sand airfield  pavements. Volume change is generally not a great concern in relation to compaction except for clay soils where compaction does have a marked influence. For these soils, the greater the density, the greater the potential volume change due to swelling, unless the soil is restrained [6].

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Chapter 4:

TYPES OF COMPACTION

There are four types of compaction effort on soil or asphalt:

1. Vibration 2. Impact 3. Kneading 4. Pressure

Each of these types is carried out using one of two types of forces: static or vibratory. Static force relies on the weight of a machine to apply downward pressure on soil, thus compressing the soil particles. Adding weights to, or removing them from, the compaction machine can adjust the amount of pressure. Although effective, static compaction is best suited for the upper soil layers. The types of compaction that fall under static are kneading and pressure

Vibratory forces, on the other hand, uses mechanically driven force to apply downward  pressure in addition to the weight of the machine. The mechanically driven force is an applied vibratory force that rotates the eccentric weight of a piston and spring combination .Compactors achieves compaction through the use of delivering rapid blows, or impacts, to the surface. This is effective in that it not only compacts the top layers, but the deeper layers as well. With vibration, the particles are set in motion and moved closer together to form a high density [7].

4.1 Lab Compaction Test

Tests to determine optimum moisture content are done in the laboratory. The most common is the Proctor Test, or Modified Proctor Test. A particular soil needs to have an ideal (or optimum) amount of moisture to achieve maximum density. This is important not only for durability, but will save money because less compaction effort is needed to achieve the desired results.

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Proctor Test (ASTM D1557-91)

The Proctor, or Modified Proctor Test, determines the maximum density of a soil needed for a specific job site. The test first determines the maximum density achievable for the materials and uses this figure as a reference. Secondly, it tests the effects of moisture on soil density. The soil reference value is expressed as a percentage of density. These values are determined before any compaction takes place to develop the compaction specifications. Modified Proctor values are higher because they take into account higher densities needed for certain types of construction projects.

Test methods are similar for both tests. [See Figure 4] [4],[8].

Effect of Compactive Effort:

As the compactive effort increases, the maximum dry density increases and OMC reduces for the same soil.

Fig 3 Effect of Compactive Effort:

The line of optimum moisture contents is usually around 85% saturation and the optimum moisture content decreases with increasing compactive effort.

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Automated Proctor Equipment Manual Proctor Test

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4.2 Field Compaction Tests

It is important to know and control the soil density during compaction. Following are common field tests to determine on the spot if compaction densities are being reached.

Fig 5 Field density Test

Sand Cone Test (ASTM D1556-90)

A small hole (6” x 6” deep) is dug in the compacted material to betested. The soil is removed and weighed, then dried and weighedagain to determine its moisture content. A soil’s moisture is figuredas a percentage. The specific volume of the hole is deter mined  byfilling it with calibrated dry sand from a jar and cone device. Thedry weight of the soil removed is divided by the volume of sandneeded to fill the hole. This gives us the density of the compactedsoil in lbs per cubic foot. This density is compared to the maximum .Proctor density obtained earlier, which gives us the relative densityof the soil that was  just compacted. [See Figure 6] [8].

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Fig6

Nuclear Density (ASTM D2922-91)

 Nuclear density meters are a quick and fairly accurate wayof determining density and moisture content. The meter usesa radioactive isotope source (Cesium 137) at the soil surface (backscatter) or from a probe placed into the soil (directtransmission). The isotope source gives off photons (usuallyGamma rays) which radiate back to the meter’s detectors on thebottom of the unit. Dense soil absorbs more radiation than loosesoil and the readings reflect overall density. Water content (ASTMd3017) can also be read, all within a few minutes. A relativeProctor density is obtained after comparing maximum density withthe compaction results from the test. [See Figure 7] [9].

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Chapter 5:

COMPACTION IN FIELD OF CIVIL

In earlier days, embankment design and construction were not given adequate attention. Embankments were constructed and left for compaction by natural process. Due to loads imposed by heavier axle loads, very high degree of sub-grade support have become necessary in present scenario which requires fast and heavy compaction by suitable compacting equipments. Initially its application was restricted to pavement materials such as fine crushed rocks, gravels and soft rocks but this has been extended to control of earthworks in general

.

Presently compaction is used in various fields of civil engineering like-Railways

.

Airfield pavements.

Earth structures, such as embankments. Subgrades, and bases for road.

Harbours.

Foundations of structural buildings etc…

Compacting gravel subgrade for runways The main embankment Bouquet CanyonDam

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5.1 Types of Compaction Equipments

A large variety of mechanical equipments is available for compaction of soil but soil type and moisture condition will often dictate the type of equipments and method of use [7].

Some important compacting equipment are given below:

-1. Light compacting equipments (Rammers/Plate compactors) 2. Smooth wheel rollers

3. Sheepsfoot rollers 4. Pneumatic tyred rollers 5. Vibratory rollers

6. Grid rollers

7. Dynamic compaction 8. Vibrofloatation

9. High-Energy Impact Roller Compaction

The details about various types of rollers and equipmentsare given as below:

-Rammers:

Rammers are the light compacting equipments used for small areas, which provide impact load. These may be hand or machine operated.

The area of base is normally 15cm x 15cm or 20cm x 20cm or more. Free fall rammers can be heavier type also weighing 2 or 3 tonne lifted and dropped by cables to a height of 1 or 2m to compact large rock fragments

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Smooth Wheel Rollers:

These rollers have one large steel drum in front and two steel drums on the rear. The gross weight of these rollers is in the range of 8-10 tonne. The performance of a smooth wheel roller depends upon its load per cm width and diameter of the roll.

Fig 9

Sheepsfoot Roller:

For compacting heavy clays and silty clays, sheepsfoot rollers are found to be very effective. These rollers are employed in road and rail projects. They consist of steel drum/s on which projecting legs are fixed which may apply pressure up to 14kg/sqcm or more.

Fig 10

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with uniform pressure throughout the width. The front axle may have four pneumatic smooth wheels where as there can be five wheels on the rear axles.

Fig11

Vibratory Rollers:

Latest specifications of earthwork invariably recommend vibratory rollers. These rollers are helpful from several considerations

like:-(i) Higher compaction level can be achieved with maximum work (ii) Compaction can be done up to greater depths

(iii) Output is many times more than conventional rollers

Vibratory rollers are similar to smooth wheel rollers with the modification that the drum or drums are made to vibrate by employing rotating or reciprocating mass.

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Grid Rollers:

These rollers have a cylindrical heavy steel surface consisting of a network of steel bars forming a grid with squire holes and may be ballasted with concrete blocks. They are generally towed units and can operate at speeds between 5 and 24 kmph. Typical weights vary between 5.5 tonnes net and 15 tonnes ballasted [7].

Fig 13

Deep Dynamic Compaction(DDC):

Fig14

Deep Dynamic Compaction (DDC) densifies marginal materials using high levels of impact energy at the surface.A tamper with a weight of 5 to 40 tons is dropped using a

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size distribution. Five to 15 blows per grid point are applied. The first phase is the high-energy phase to improve the deeper layers. This is followed b y a low-high-energy phase to densify the upper layers. In the low-energy phase, the tamper is only raised 15 to 20 feet. Backfilling the craters and additional passes may be required [10].

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Vibroflotation:

Fig 15

Suitable for granular soils Practiced in several forms:

1. Vibro – compaction 2. Vibro-replacement

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Vibro-Compaction:

The vibrator penetrates to design depth, aided by water and/or air flushing. The vibrator is then raised in discrete increments following a pre-determined holding time or until a  build-up of resistance at each level indicates that the desired degree of compaction has  been achieved. If the objective is to maintain original site elevation, additional material

may be introduced to compensate for surface lowering induced by the process.

Vibro-Compaction ground improvement has been effective in treating suitable subsurface conditions to depths greater than 125 feet, with a more practical limit of around 70 feet for crane-mounted systems and 28 feet for excavator-mounted systems.

Vibro Replacement:

Vibro replacement was used for a similar process using water as the jetting medium with the addition of a graded stone aggregate added down the probe hole and forced out laterally into the formation soils, to create stone columns. Latterly, Vibro replacement is also done using compressed air for jetting in clayey soils above the water table.

Columns are constructed by the introduction of natural or recycled aggregate backfill to the tip of the vibrator. The horizontal action of the vibrator displaces the stone laterally to form a dense structural element. As successive stone columns are formed, the intervening soil is densified, creating an integrated soil/stone matrix capable of supporting high, vertical loads.

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Stage1 Vibrator makes a hole in weak ground. Stage 2 hole backfilled

Stage 3 and compacted

Stage 4 Densely compacted stone column

Vibro Stone Column (Bottom feed method):Method does not require water for  penetration thus avoiding the disposal of large quantities of muck and also making

environmental friendly.

Rig used: Vibrocat, operational advantage is it is able to exert a pull down force improving penetration speed

Vibrocat feeds the Coarse granular material to the tip of vibrator with the aid of  pressurized air.Installation method consists of alternate step of penetration and retraction.

During retraction gravel runs into the annular space created and then compacted using vibrator thrusts and compressed air.

VIBROFLOTATION PROBE SPACING

Spacing of the grid varies depending on soil type, density to be achieved and  probe/vibrator characteristics, but generally lies in the range of 1.5 to 3.5m[11].

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Figure 16

High-energy impact rollers (IR) have been increasingly used for earthworks by compacting on-site soils. The IR applies high energy to the ground and densifies deeper soils than conventional rollers and plate-type compactors. A trial program was implemented on the third runway of the Shanghai Pudong International Airport in China to validate the performance of the IR technology. Field monitoring and in-situ testing were undertaken during or after the IR compaction. The cone penetration data indicated that significant improvement in soil properties was measured up to a depth of 4 m after 20 to 25 passes of compaction. However, the improvement of the properties of the very soft silty clay at the depth of 1 to 2 m was limited. The vibration monitoring data suggested that the IR compaction with 12-ton impact module would not cause damage to buildings at a distance of 9.5 m away from the boundary of the compaction path.

One disadvantage of this technology is that the high-impact forces disturb (i.e., loosen) the top 0.25 to 1.5 ft of the surface so the top layer needs additional compaction with conventional rollers. The vibrations caused by the impact rollers and their effect on

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nearby structures (e.g., underground utilities/pipe lines or nearby building structures) are important to consider with this technology[12].

COMPACTION:

ASSOCIATED COSTS

From the graph we can say that High-energy impact rollers is effective and economical up to a depth of 4m. Deep Dynamic Compaction is effective up to 6m andVibro compaction is best suited and economic for depth more than 10 to 12m [11].

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5.2Factors Affecting Compaction inthe Field

Compaction of a particular soil is affected by following given factors – 

(i) COMPACTIVE EFFORT

In modern construction projects, heavy compaction machinery is deployed to provide compaction energy. Types of machinery required are decided based on type of soil t o be compacted. Different type of action is effective in different type of soils such as for cohesive soils; sheepsfoot rollers or pneumatic rollers provide the kneading action. Silty soils can be effectively compacted by sheepsfoot roller/pneumatic roller or smooth wheel roller. For compacting sandy and gravelly soil, vibratory rollers are most effective. If

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(ii) MOISTURE CONTENT

Proper control of moisture content in soil is necessary for achieving desired density. Maximum density with minimum compacting effort can be achieved by compaction of soil near its OMC (Optimum Moisture Content). If natural moisture content of the soil is less than OMC, calculated amount of water should be added to soil with sprinkler attached to water tanker and mixed with soil by motor grader for uniform moisture content. When soil is too wet, it is required to be dr ied by aeration to reach up to OMC.

(iii) SOIL TYPE

Type of soil has a great influence on its compaction characteristics. Normally, heavy clays, clays and silt offer higher resistance to compaction where as sandy soils and coarse grained or gravelly soils are amenable for easy compaction. The coarse-grained soils yield higher densities in comparison to clays. A well-graded soil can be compacted to higher density.

(iv) LAYER THICKNESS

The more the thickness of layer of earth subjected to field compaction, the less the energy input per unit weight of soil and hence, less is the compaction under each pass of the roller. Suitable thickness of soil of each layer is necessary to achieve uniform thickness. Layer thickness depends upon type of soil involved and type of roller, its weight and contact pressure of its drums. Normally, 200-300 mm layer thickness is optimum in the field for achieving homogeneous compaction.

(v) CONTACT PRESSURE

Contact pressure depends on the weight of the roller wheel and the contact area. In case of pneumatic roller, the tyre inflation pressure also determines the contact pressure in

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(vi) NUMBER OF ROLLER PASSES

Density of the soil increases with the number of passes of rollers but after optimum number of passes, further increase in density is insignificant for additional number of cases. For determination of optimum number of passes for given type of roller and optimum thickness of layer at a predetermined moisture content, a field trial for compaction is necessary.

(vii) SPEED OF ROLLING

Speed of rolling has a very important bearing on the roller output. The greater the speed of rolling, the more the length of embankment that can be compacted in one day. Speed was found to be a significant factor for vibratory rollers because its number of vibrations  per minute is not related to its forward speed. Therefore, the slower the speed of travel,

the more vibrations at a given point and lesser number of pass required to attain a given density [5].

5.3How Much Compaction Is To Be Done?

With the help of field compaction trials, the appropriate type of roller for particular type of soil, optimum depth of layer of soil to be compacted and optimum moisture content of the soil to be used for compaction can be determined. For this, a ramp of following dimension is prepared. Each strip is rolled with using different moisture contents, type of roller and different thickness of lift of soil. Finally, by plotting the graph between various  parameters used, the desired parameters are determined [13].

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The number of passes needed to achieve the desired compaction depends on the lift thickness, contact pressure, and soil moisture content.

 Number of passes versus average settlement (compression) in inches for various modern compactors ( study report on compaction equipments and construction machinery) [13].

5.4 Intelligent Compaction (IC)

Intelligent Compaction is an innovation continuous compaction control process that measures material stiffness during the compaction process, analyzes the information  being collected, makes an adjustment of vibratory roller parameters, and executes the

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Vibratory rollers with a feedback control measurement system

Measures material stiffness , Control system automatically changes parameters (amplitude and frequency) based on the measured material stiffness

GPS-based documentation system

Continuous monitoring material’s stiffness and corresponding roller locations .Real-time displaying color-coded mapping of stiffness

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Intelligent compaction can greatly improve the quality and uniformity of compaction which are critical for long-lasting performance of pavements

When and how much of compaction is achieved, avoiding under or over compaction . Where compaction is achieved or not achieved can easily be known [14].

Currently (Empirical Pavement design, R Value)

Specific Relative Density (Proctor Test) Specific Moisture Limits (Proctor Test) Test Rolling (optional)

Future (Mechanistic Pavement Design, Modulus)

QC: Intelligent Compaction Equipment QC/QA: Continue to Specify Moisture QA: Specify Modulus and Strength

(QC Quality Control, QA Quality Assurance)

QC Testing (verified by LWD),QA Testing (verified by PLT ). Intelligent compaction benefits

Cover 100% of the rolling area, resulting in better control of density and its uniformity. Replace conventional proof rolling ,identify soft spots in real time ,improve pavement  performance ,improve site safety [14].

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Chapter 6:

CONCLUSION

Compaction is the densification of an unsaturated soil by the reduction in the voids volume filled with air, the volume of solids and water content essentially remaining the same. The important factors which govern the compaction process are the moisture content, the soil type. This paper has discussed these factors in detail. Various improvements in the engineering properties of soil that are achieved through compaction are critically evaluated. This paper has discussed how the laboratory compaction test results can be extended to achieve the required field compaction.

Soil Compaction is very critical for any development. Failure to make sure the effectiveness of an entire process may cause disaster in future. Developers, consultants, local authorities and the contractor must aware the bad consequences that probably happen if neglecting any aspect in the process and should be responsible to the scope of works that delegated to them by the users. Hopefully this short presentation will benefits to the viewers in understanding the basic principles in Soil Compaction theory that can be useful. THANK YOU…

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Chapter 7:

REFRENCES

[1] Das ,B. M. (1985). “Advanced Soil Mechanics”. McGraw-Hill Book Company, New York.

[2] Rattan Lal, Manoj K. Shukla (2004). “Principles of Soil Physics”.  MARCEL DEKKER, INC. NEW YORK

[3] Das, Braja M. (2002). “ Principles of Geotechnical Engineering ”. first edition, Pacific Grove, CA

[4] ME Sumner (1999). “Hand Book of Soil Science”. CRC Press , MULTIQUIP INC. Boca Raton, Florida.

[5] Kumar Neeraj Jha (2011). “Construction Project Management :Theory and Practice” .Pearson Education India.

[6] Hamza M.A, Al-Adawi S.S, Al-Hinai K.A. “Effects of combined soil water and external load on soil compaction”.’Soil Research’, 2011, 49, 135-142

[7] Study Report on Compaction Equipments and Construction Machinery (2005) Report.No.Ge- R-76.“Geotechnical Engineering Directorate Research Designs & Standards Organization” Lucknow-11

[8] ASTM, Standard Practice for Quality Control of Soil Compaction using (D1556-90, D1557-91, D2922-91,d3017) American Society of Testing and Material. USA.

[9] Selim ALTUN, Alper SEZER. “Investigation of Parameters of Compaction Testing” Turkish J. Eng. Env. Sci. 32 (2008) , 201  –  209.

[10] Lukas, R.G. (1986). “Dynamic Compaction for Highway Construction Volume I: Design and Construction Guidelines.” U.S. Department of Transportation, Federal Highway Admin., Washington, D.C., FHWA/RD-86/133.

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[11] UMASS Lowell (2013) 14.330. “Soil Mechanics and Soil Compaction”  A Basic  Handbook by Multi Quip.

[12] Clegg, B., and A. R. Berrangé. 1971. “The development and testing of an impact roller.” Transactions of the South African Institution of  Civil Engineers. Vol. 13, No. 3,  pp. 65-73.

[13] Proctor, R. R. (1933). “ Fundamentals principles of soil compaction. Engineering news-record”.Vol. 111, No. 9, 245-248.

[14] George Chang, Qinwu Xu, “Accelerated Implementation of Intelligent Compaction

Technology for Embankment Subgrade Soils, Aggregate Base, and Asphalt Pavement Materials” .US Department of Transportation ,Federal Highway Administration.

[15] Kyu-Sun Kim, Dante Fratta, and Haifang Wen. “Field Measurements for the Effectiveness of Compaction of Coarse-grained Soils”. KSCE Journal of Civil Engineering (2014) 18(2):497-504.

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