BASIC CIVIL ENINEERING · the development of Engineering in the Pharaonic civilization for several reasons, because it consists of 2,300,000 blocks of rock with the mass of 2 to 30

BASIC CIVIL ENINEERING

S S NAYAK,KIT Page 1

INTRODUCTION

Introduction-Civil engineering is a professional engineering discipline that deals with the

design, construction, and maintenance of the physical and naturally built environment,

including public works such as roads, bridges, canals, dams, airports, sewerage systems,

pipelines, structural components of buildings, and railways.

Scope of civil engineering-The main scope of civil engineering or the task of civil

engineering is planning, designing, estimating, supervising construction, managing

construction, execution, and maintenance of structures like building, roads, bridges, dams,

etc.

Broad disciplines of civil engineering-Civil engineering is a broad field: structural

engineering, geotechnical engineering, water resources engineering, and transportation

engineering are some of its subspecialties. Understanding structural engineering is a basic

requirement of bridge design; it is system of static forces applied to a structure. The details

lead to a system of linear equations that can be solved in a spreadsheet. The Method of Joints

takes advantage of free-body diagrams to determine the forces acting at the ends of

each strut in a truss. Geotechnical engineering requires a working knowledge of soil

mechanics and foundation engineering, which are integral to designing and constructing a

solid foundation and supporting a heavy structure. Effective stress is a key concept in this

field that when properly applied helps with the construction of these structures. Water

resources engineering applies to the placement of dams, which requires estimation of

required capacity and yield. Finally, transportation engineering is applied to road design to

estimate the capacity of a road based on kinematics and empirical rules describing the

separation of vehicles speeding on the highway.

Early constructions and developments over time-The civil engineering is one of the oldest

branches of engineering because of its relation to the establishment of built environment. It

includes design, planning and implementation as well as the work of developing and

reconstruction and restoration of buildings such as bridges, dams and ports, also, the planning

of residential cities and the establishing of services such as sanitation stations, power stations,

roads and transportation network.

Though the expression itself was used as a scientific term in ancient Rome, it is not possible

to know when did the science of civil engineering originate, but we can say that civil

engineering has started and developed with the development of mankind through the ages and

the features of engineering in ancient times was developed into a science to be studied till

modern times.

For example the pyramids of Giza pose as a model of architectural excellence, and illustrate

the development of Engineering in the Pharaonic civilization for several reasons, because it

consists of 2,300,000 blocks of rock with the mass of 2 to 30 tons per block, but so far,

science was unable to reach the method of how they were built.

The Great Wall of China, considered one of the Seven Wonders of the World as it is built in

less than ten years and with a length of more than 2500 kilometers.

Development of various materials of construction and methods of construction-The core of a

construction project apart from its design is the materials used. Construction has always been

highly related to its materials, which have been an essential component since as far back as

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400 BC! Buildings and structures including bridges, dams, roads and canals have been built

since pre-history. Building materials thus have a long history of around some thousands of

years.

Very initially, buildings were made of perishable materials like leaves, branches and animal

hides. With invention, materials like stone, clay and timber were used. Slowly came the age

of bricks and concretes. Then, with industrial revolution, came metals and steel, which was

considered as a revolution of architecture. Today, we see buildings made of bricks, concrete,

wood, steel and glass. These materials are no more a revolution.

Now, other innovative materials are coming up in the industry of architecture. With ongoing

research and innovative technologies, a variety of modern material options have become

available today. With the styles and designs on modern construction, we need materials that

can maintain structural strength while reducing its impact on the environment. Polycarbonate

is one of the latest materials used in construction because they can withstand harsh weather

conditions like wind, rain, hail and snow. They are also highly corrosion resistant and can

also resist fire. Thus, polycarbonate roofing is one of the best and most popularity-gaining

materials today that is used in greenhouses, skylights, pergolas, sidings, sidelights and many

other roofing applications.

Modern construction materials also need to be able to adapt to various climatic conditions

from freezing sub-zero temperatures to dry heat or high humidity. Ever since man started

constructing dwellings to reside in, building materials have been evolving only in an attempt

to defeat weather. Let us look at the evolution in detail.

• Mud and clay were among the first construction materials. Clay would be easily

formed into shapes. Mud was held together with the help of hay, straw, sticks and

other organic fibers and dung. Ice was used in the Arctic areas to form igloos.

• Then came the time when wood, logs, sticks and thatch were used. Large uncut rocks

were piled together to form historic structures. Further, man started building

structures with advanced composite materials like cement and concrete, reinforced

with steel or other metals.

• Men then shifted from mud huts and tents to the age of skyscrapers made of glass or

metal, which has made buildings more practical than in history. Today, most high-rise

buildings are made with steel or other metals.

• With steel and metals getting sensitive to corrosion, people started coming up with

other options that could last longer. This was when plastics came up that are formed

of polymers, and can be easily moulded while in liquid state. Moreover, plastic is very

light in weight and comparatively cheaper.

You can opt for polycarbonate greenhouse panels, solid textured polycarbonate sheets,

multiwall polycarbonate sheets, corrugated and profiled polycarbonate sheets and UPVC

corrugated/synthetic sheets from Tuflite Polymers for all your construction requirements to

get the best possible products at the most pocket-friendly prices.

Building Materials and Building Construction

Brick as a construction material- Different types of bricks are used in masonry construction

based on material such as clay, concrete, lime, fly ash etc. Filed field identification of bricks

for their properties, uses and suitability for different construction works are important.

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A brick is an important construction material which is generally available in rectangular

shape manufactured from clay. They are very popular from olden days to modern days

because of low cost and durability.

Types of Bricks used in Masonry Construction

Based on the manufacturing process, bricks are broadly classified into two types, 1. Sun-

Dried or unburnt bricks 2. Burnt bricks

1. Sun-Dried or Unburnt Clay Bricks

Sun-dried or unburnt bricks are less durable and these are used for temporary structures.

Unburnt bricks preparation involved in 3 steps they are preparation of clay, molding and

drying.

After molding, bricks are subjected to sunlight and dried using heat from sun. So, they are not

that much strong and they also have less water resistance and less fire resistance. These

bricks are not suitable for permanent structures.

2. Burnt Clay Bricks

Burnt bricks are good quality bricks but however they also consist some defected bricks. So,

burnt bricks are classified into four types and they are

• First class bricks

• Second class bricks

• Third class bricks

• Fourth class bricks

First Class Bricks

First class bricks are good quality bricks compared to other classes. They are molded by

table-molding and burnt in large kilns. So, these bricks contain standard shape, sharp edges

and smooth surfaces.

They are more durable and having more strength. They can be used for permanent structures.

However, because of their good properties they are costly than other classes.

Second Class Bricks

Second class bricks are moderate quality bricks and they are molded by ground-molding

process. These bricks are also burnt in kilns. But because of ground molding, they do not

have smooth surfaces as well as sharp edges.

The shape of bricks also irregular due to unevenness in ground. These also will give best

results in strength and durability. Smooth plastering is required on the brick structure.

Third Class Bricks

Third class bricks are poor quality bricks which are generally used for temporary structures

like unburnt bricks. These are not suitable for rainy areas. They are ground-molded type

bricks and burnt in clamps. The surface of this type of bricks are rough and they have unfair

edges.

Fourth Class Bricks

Fourth class bricks are very poor quali

ty bricks and these are not used as bricks in the structure. They are crushed and used as

aggregates in the manufacturing of concrete. They are obtained by over burning, because of

this they gets overheated and obtains brittle nature. So, they can break easily and not suitable

for construction purpose.



3. Fly Ash Bricks

Fly ash bricks are manufactured using fly ash and water. These bricks have better properties

than clay bricks and great resistant to freeze thaw cycles. These bricks contains high

concentration of calcium oxide which is used in cement production, thus it is also called as

self-cementing brick. Fly ash bricks are lightweight and thus it reduces self weight of

structures.

The advantages of fly ash bricks over clay bricks are that they have high fire insulation, high

strength, uniform sizes for better joints and plaster, lower water penetration, does not require

soaking before use in masonry construction.

4. Concrete Bricks

Concrete bricks are manufacturing using concrete with ingredients as cement, sand, coarse

aggregates and water. These bricks can be manufactured in sizes as required.

The advantages of using concrete bricks over clay bricks are that they can be manufactured at

construction site, reduces quantity of mortar required, can be manufactured to provide

different colors as pigmented during its production.

Concrete bricks are used for construction of masonry and framed buildings, facades, fences,

and provide an excellent aesthetic presence.

5. Engineering Bricks

Engineering bricks have high compressive strength and are used special applications where

strength, frost resistance, acid resistance, low porosity is required. These bricks are

commonly used for basements where chemical or water attacks are prevalent and for damp

proof courses.

6. Sand Lime or Calcium Silicate Bricks

Calcium silicate bricks are made of sand and lime and popularly known as sand lime bricks.

These bricks are used for several purposes in construction industries such as ornamental

works in buildings, masonry works etc.

Identification of Bricks Quality at Construction Site

To build a good quality structure, observing quality of materials is important. Here we

discuss about how good bricks are identified at construction site.

• The colour of bricks should be bright and uniform.

• They should be well burned and having smooth surfaces and sharp edges.

• Thermal conductivity of bricks should be less and they should be sound proof.

• They shouldn’t absorb more than 20% by weight when we placed it in water.

• When we struck two bricks together, ringing sound should be delivered.

• Structure of bricks should be homogeneous and uniform.

• The bricks should not break when we dropped it form 1m height.

• There should not be any scratch left on the brick when we scratched with finger nail.

• There should not be any white deposits on brick, when we soaked it in water for 24

hrs.

Properties of Bricks

Following are the properties of bricks which represents the importance of bricks in

construction.



i. Hardness ii. Compressive strength iii. Absorption

Hardness of Bricks

A good quality brick will have resistance against abrasion. This property is called hardness of

brick which helps to give permanent nature of brick structure. Because of this property bricks

do not damaged by scraping.

Compressive strength of Bricks

Compressive strength or crushing strength is the property of brick which represent the

amount of load carried by brick per unit area. According to BIS the minimum compressive

strength of brick should be 3.5N/mm2. Crushing strength of bricks reduced when they are

soaked in water.

Crushing strength of Bricks Grades

7 – 14 N/mm2 Class A

>14N/mm2 Class AA

Absorption of Bricks

Bricks are generally absorbs water but having limits. Absorption limit percentage by weight

for different classes of bricks is tabulated below.

Class of Bricks Water Absorption % by weight

Heavy duty bricks (special made) Only 5%

First class 20%

Second class 22%

Third class 25%

Uses of Different Types of Bricks

Bricks are widely used in construction industry for different purposes as following.

• Good quality bricks (1st and 2nd class) are used in the construction of buildings,

tunnels, pitching works etc.

• 3rd class and unburnt bricks are used for temporary structures.

• 4th class bricks are used as aggregate for making concrete.

• Bricks are also used for architectural purposes to give aesthetic appearance to the

structure.

Importane of bricks- It is always desirable to use the best quality brick in constructions.

Therefore, the Characteristics of a good brick must be investigated. Generally good bricks

possesses following properties



1)Bricks should be uniform in color, size and shape. Standard size of brick should be

maintained.

2)They should be sound and compact.

3)They should be free from cracks and other flaws such as air bubbles, stone nodules etc.

with sharp and square edges.

4)Bricks should not absorb more than 1⁄5

of their own weight of water when immersed in water for 24 hours (15% to 20% of dry

weight).

Here some main uses of construction brick are given below.

1)Construction of walls of any size

2)Construction of floors

3)Construction of arches and cornices

4)Construction of brick retaining wall

5)Making Khoa (Broken bricks of required size) to use as an aggregate in concrete

6)Manufacture of surki (powdered bricks) to be used in lime plaster and lime concrete

STONE

Classification of Stones-They may be classified in the following four ways. Stones

are classified as per the classification if their parent rocks. physical classification, Geological

classification, practical classification, Scientific classification.

Classification of Stone

• Physical classification

o Stratified stone

o Unstratified stone

• Geological classification

o Igneous Rocks

o Sedimentary Rocks

o Metamorphic Rocks

• Scientific or engineering classification

o Silicious Rocks

o Argillaceous Rocks

• Practical classification

o Granite

o Sandstone

o Limestone

o Slate

Physical Classification of stone

Depends upon Physical classification rocks are classified into two groups, namely, stratified

and unstratified.



Stratified Stones

These stones are derived from sedimentary rocks. These stones are found in layers one above

another Limestone and sandstones are the stratified stone.

Unstratified Stones

These stones do not show any types of layers. Granite, marble, trap, etc. are the unstratified

stones.

Geological classification of stone

Depends upon Geological formation of rocks, stones are classified as igneous, sedimentary

and metamorphic rocks.

• Igneous Rocks

• Metamorphic rocks

• Sedimentary rocks

Igneous Rocks

These are formed by the cooling of molten lava. When the structure of stone upon the rate of

cooling of lava. When this lava becomes hard on cooling and formed igneous rocks. These

rocks are durable, hard, massive and stronger than other stones.

Sedimentary Rocks

These are formed by the deposition of sediments due to the action of air and water. Due to the

action of air and water. Due to the action of high-speed wind and heavy rain, igneous rocks

are disintegrated and deposited in layers, one the earth crust and formed sedimentary rocks.

Limestone, sandstone, and slate are the sedimentary rocks.

Metamorphic rocks

These rocks are either the sedimentary rocks or the igneous rocks whose physical and

chemical properties are changed due to the action of high temperature and pressure.

Dolomite, slate, marble, gneiss are the metamorphic rocks.

Scientific or Engineering classification of stone

• Silicious Rocks

• Argillaceous Rocks

• calcareous rocks

Silicious Rocks

These have silica as the principal constituent. These rocks are hardly affected by weathering

action. These are very hard and also durable. Granite, sandstone, gneiss, basalt, trap syenite

are the siliceous rocks.



Argillaceous rocks

These have clay as the principal constituent. These stones are hard and durable but brittle in

nature. Slate and laterite are the Argillaceous rocks.

Calcareous Rocks

These have carbonate of lime as the principal constituent. Limestone, marble, kankar,

dolomite, and gravel are the calcareous rocks.

A particle of stone Classification

Depends upon physical characteristics, stones are classified as under-

• Granite

• Sandstone

• Limestone

• slate

Granite

The formation of minerals of granite is quartz, feldspar, and mica. It’s also having specific

gravity 2.63 to 2.75. They also having light or dark grey, pink or reddish color. It’s also

having a crushing strength of 1000 to 1400 kg/cm2. It also having light or dark grey, pink or

reddish color. They also have a crushing strength of 1000 to 1400 kg/cm2. It is very strong

heavy, hard durable. It contains silica 60 to 80%.

Sandstone

Sandstone is composed of sand grains, cemented together by calcium or magnesium

carbonate or silicic acid, alumina, and also oxide of iron. It also has a specific gravity 2.25.

They are also white, grey, brown or red in color. it’s having a crushing strength of 400 to 800

kg/cm2. These strong under pressure, but it is flaky when it contains mica. These are hard,

non-absorbent, strong and heavy. They are easily workable and also resists the weathering in

a better way. They use to face work and ornamental work.

Limestone

These are carbonate of lime intermixed with other minerals and impurities such as silica,

magnesium carbonate, aluminum, and iron. It’s also having yellow, brown, grey or violet

color. It’s also having specific gravity 2.56. They having crushing strength 300 to 500 kg/m2.

These are soft and absorbent and so they do not resist the weathering action well. Chalk,

marbles are examples of limestone.

Slate

These are also composed of silica and alumina. These are also usually grey-black or dark

blue. It’s also having specific gravity 2.8. It’s also having crushing strength 700 to 2100



kg/cm2. When these are hard and tough, laminar in nature. It’s of useful for roofing as well as

flooring.

Cement

Classification of Cement-There are various types of cement used in concrete construction.

Each type of cement has its own properties, uses and advantages based on composition

materials used during its manufacture.

13 Types of Cement and their Uses

1. Ordinary Portland Cement (OPC)

2. Portland Pozzolana Cement (PPC)

3. Rapid Hardening Cement

4. Quick setting cement

5. Low Heat Cement

6. Sulphates resisting cement

7. Blast Furnace Slag Cement

8. High Alumina Cement

9. White Cement

10. Coloured cement

11. Air Entraining Cement

12. Expansive cement

13. Hydrographic cement

1. Ordinary Portland Cement (OPC)

Ordinary Portland cement is the most widely used type of cement which is suitable for all

general concrete construction. It is most widely produced and used type of cement around the

world with annual global production of around 3.8 million cubic meters per year. This

cement is suitable for all type of concrete construction.

2. Portland Pozzolana Cement (PPC)

Portland pozzolana cement is prepared by grinding pozzolanic clinker with Portland cement.

It is also produced by adding pozzolana with the addition of gypsum or calcium sulfate or by

intimately and uniformly blending portland cement and fine pozzolana.

This cement has high resistance to various chemical attacks on concrete compared with

ordinary portland cement and thus it is widely used. It is used in marine structures, sewage

works, sewage works and for laying concrete under water such as bridges, piers, dams and

mass concrete works etc.

3. Rapid Hardening Cement

Rapid hardening cement attains high strength in early days it is used in concrete where

formworks are removed at an early stage and is similar to ordinary portland cement (OPC).

This cement has increased lime content and contains higher c3s content and finer grinding

which gives greater strength development than OPC at an early stage.

The strength of rapid hardening cement at the 3 days is similar to 7 days strength of OPC

with the same water-cement ratio. Thus, advantage of this cement is that formwork can be

removed earlier which increases the rate of construction and decreases cost of construction by

saving formwork cost.

Rapid hardening cement is used in prefabricated concrete construction, road works, etc.



4. Quick setting cement

The difference between the quick setting cement and rapid hardening cement is that quick

setting cement sets earlier while rate of gain of strength is similar to Ordinary Portland

Cement, while rapid hardening cement gains strength quickly. Formworks in both cases can

be removed earlier.

Quick setting cement is used where works is to be completed in very short period and for

concreting in static or running water.

5. Low Heat Cement

Low heat cement is prepared by maintaining the percentage of tricalcium aluminate below

6% by increasing the proportion of C2S. This makes the concrete to produce low heat of

hydration and thus is used in mass concrete construction like gravity dams, as the low heat of

hydration prevents the cracking of concrete due to heat.

This cement has increased power against sulphates and is less reactive and initial setting time

is greater than OPC.

6. Sulphates Resisting Cement

Sulfate resisting cement is used to reduce the risk of sulphate attack on concrete and thus is

used in construction of foundations where soil has high sulphate content. This cement has

reduced contents of C3A and C4AF.

Sulfate resisting cement is used in construction exposed to severe sulphate action by water

and soil in places like canals linings, culverts, retaining walls, siphons etc.

7. Blast Furnace Slag Cement

Blast furnace slag cement is obtained by grinding the clinkers with about 60% slag and

resembles more or less in properties of Portland cement. It can be used for works economic

considerations is predominant.

8. High Alumina Cement

High alumina cement is obtained by melting mixture of bauxite and lime and grinding with

the clinker. It is a rapid hardening cement with initial and final setting time of about 3.5 and 5

hours respectively.

The compressive strength of this cement is very high and more workable than ordinary

portland cement and is used in works where concrete is subjected to high temperatures, frost,

and acidic action.

9. White Cement

It is prepared from raw materials free from Iron oxide and is a type of ordinary portland

cement which is white in color. It is costlier and is used for architectural purposes such as

precast curtain wall and facing panels, terrazzo surface etc. and for interior and exterior

decorative work like external renderings of buildings, facing slabs, floorings, ornamental

concrete products, paths of gardens, swimming pools etc.

10. Colored cement

It is produced by mixing 5- 10% mineral pigments with ordinary cement. They are widely

used for decorative works in floors.

11. Air Entraining Cement

Air entraining cement is produced by adding indigenous air entraining agents such as resins,

glues, sodium salts of sulphates etc. during the grinding of clinker.



This type of cement is especially suited to improve the workability with smaller water cement

ratio and to improve frost resistance of concrete.

12. Expansive Cement

Expansive cement expands slightly with time and does not shrink during and after the time of

hardening . This cement is mainly used for grouting anchor bolts and prestressed concrete

ducts.

13. Hydrographic cement

Hydrographic cement is prepared by mixing water repelling chemicals and has high

workability and strength. It has the property of repelling water and is unaffected during

monsoon or rains. Hydrophobic cement is mainly used for the construction of water

structures such dams, water tanks, spillways, water retaining structures etc.

Tests on Cement

The following tests are conducted on cement in the laboratory are as follows:

1. Fineness Test

2. Consistency Test

3. Setting Time Test

4. Strength Test

5. Soundness Test

6. Heat of Hydration Test

7. Tensile Strength Test

8. Chemical Composition Test

Fineness test on cement

The fineness of cement is responsible for the rate of hydration, rate of evolution of heat

and the rate of gain of strength. Finer the grains more is the surface area and faster the

development of strength.

The fineness of cement can be determined by Sieve Test or Air Permeability test.

Sieve Test: Air-set lumps are broken, and the cement is sieved continuously in a circular and

vertical motion for a period of 15 minutes. The residue left on the sieve is weighed, and

it should not exceed 10% for ordinary cement. This test is rarely used for fineness.



Air Permeability Test: Blaine's Air Permeability Test is used to find the specific surface,

which is expressed as the total surface area in sq.cm/g. of cement. The surface area is more

for finer particles.

Consistency test on cement

This test is conducted to find the setting times of cement using a standard consistency test

apparatus, Vicat's apparatus.

Standard consistency of cement paste is defined as that water content which will permit a

Vicat plunger of 10 mm diameter and 50 mm length to penetrate depths of 33-35 mm within

3-5 minutes of mixing.

The test has to undergo three times, each time the cement is mixed with water varying from

24 to 27% of the weight of cement.

This test should be conducted at a constant temperature of 25°C or 29°C and at a constant

humidity of 20%.

Setting Time of cement

Vicat's apparatus is used to find the setting times of cement i.e., initial setting time and

final setting time.

Initial Setting Time: For this test, a needle of 1 mm square size is used. The needle is allowed

to penetrate into the paste (a mixture of water and cement as per the consistency test). The

time taken to penetrate 33-35 mm depth is recorded as the initial setting time.

Final Setting Time: After the paste has attained hardness, the needle does not penetrate the

paste more than 0.5 mm. The time at which the needle does not penetrate more than 0.5 mm

is taken as the final setting time.

Strength test of cement



The strength of cement cannot be defined directly on the cement. Instead the strength of

cement is indirectly defined on cement-mortar of 1:3. The compressive strength of this mortar

is the strength of cement at a specific period.

Soundness test of cement

This test is conducted in Le Chatelier's apparatus to detect the presence of uncombined

lime and magnesia in cement.

Heat of Hydration Test

During the hydration of cement, heat is produced due to chemical reactions. This heat may

raise the temperature of concrete to a high temperature of 50°C. To avoid these, in large scale

constructions low-heat cement has to be used.

This test is carried out using a calorimeter adopting the principle of determining heat gain. It

is concluded that Low-heat cement should not generate 65 calories per gram of cement in 7

days and 75 calories per gram of cement in 28 days.

Tensile Strength of Cement

This test is carried out using a cement-mortar briquette in a tensile testing machine. A 1:3

cement-sand mortar with the water content of 8% is mixed and moulded into a briquette in

the mould.



This mixture is cured for 24 hours at a temperature of 25°C or 29°C and in an atmosphere at

90% relative humidity.

The average strength for six briquettes tested after 3 and 7 days is recorded.

Chemical Composition Test

Different tests are conducted to determine the amount of various constituents of cement.

The requirements are based on IS: 269-1998, is as follows:

• The ratio of the percentage of alumina to that of iron oxide should not be less than 0.66.

• Lime Saturation Factor (LSF), i.e., the ratio of the percentage to that of alumina, iron

oxide and silica should not be less than 0.66 and not be greater than 1.02.

• Total loss on ignition should not be greater than 4%.

• Total sulphur content should not be greater than 2.75%.

• Weight of insoluble residue should not be greater than 1.50%.

• Weight of magnesia should not be greater than 5%.

Field Tests of Cement

The following tests should undergo before mixing the cement at construction sites:

Colour Test of Cement

The colour of the cement should not be uneven. It should be a uniform grey colour with a

light greenish shade.

Presence of Lumps

The cement should not contain any hard lumps. These lumps are formed by the absorption

of moisture content from the atmosphere. The cement bags with lumps should be avoided in

construction.



Cement Adulteration Test

The cement should be smooth if you rubbed it between fingers. If not, then it is because of

adulteration with sand.

Float Test

The particles of cement should flow freely in water for sometime before it sinks.

Date of Manufacturing

It is very important to check the manufacturing date because the strength of cement

decreases with time. It's better to use cement before 3 months from the date of manufacturing.

Uses of Cement

There are different uses of cement such as to make cement mortar, cement concrete which are

used in construction of various types of masonry and concrete structures. These uses of

cement are discussed in detail.

1. To prepare cement mortar

2. To prepare cement concrete

3. To build fire proof and thermal proof structures

4. To build hydrographic and frost resistant structures

5. To build chemical proof structures

6. As a grout material

7. To construct Cement concrete roads

8. To manufacture precast members

9. For aesthetic concrete construction

1. To Prepare Cement Mortar

Cement mortar is like a paste which is prepared by adding certain quantity of water to cement

and sand mixture. Cement in this case is denoted as matrix while sand is termed as adulterant.

We know Cement has good binding properties while there are other binding materials are

also available, but cement is mostly used because of its high strength and water resisting

properties. It is used to create a strong bond between bricks, stones in a masonry.



Plastering is done by cement mortar which gives smooth finish to the structure. Cement

molds of different shapes can be made using cement mortar. It is also used to seal the joints

of brickwork and stone work or cracks.

Generally, the cement sand ratio in a mortar is in between 1:2 to 1:6. The ratio of cement and

sand mix is decided based on the importance of work.

2. To Prepare Cement Concrete

Cement concrete is a major building material in the world which is widely using because of

its marvelous structural properties. The ingredients of cement concrete are cement, fine

aggregate, coarse aggregate and water respectively.

In general, ordinary Portland cement is used to prepare concrete. But for special cases or

based on different circumstances many types of cements like rapid hardening cement, high

alumina cement etc. are discovered.

3. To Build Fire Proof or Heat Proof Structures

To with stand against high temperatures and to prevent fire accidents structures should be

built with great fire-resistant materials like cement. High alumina cement is more suitable

material to make concrete for the structures in high temperature regions.

4. To Build Hydrographic and Frost Resistant Structures

Most of the hydrographic structures in the world are built using concrete with cement as

binding material. The structures built in water or in contact with water should be very strong

against moisture and they should be water tight.

Many types of cements like hydrophobic cement, expanding cement, pozzolana cement,

quick setting cement etc. are most suitable for constructing water retaining structures. Quick

setting cement is very much useful in the case when there is limited time to construct under

water structures.

Hydrophobic cement had more resistance against frost actions, so it can be used to build

structures in snow regions also.

5. To Build Chemical Proof Structures

In chemical industries, different chemicals are stored and they may damage the structure if

proper resistance is not there. Acid resistant cement is very much useful in this case.

Similarly, for the constructions under marine conditions, sewage carrying structures etc.

Sulphate resistant cement is useful.

6. For Grouting

Grouting is the process of filling cracks, joints, openings in foundations or any other

structural members to improve their strength. In general, ordinary Portland cements is used as

grout material to which required amount of water and sand is added.

To fill very fine cracks or to fill deep thin cracks micro fine cement is most suitable. Micro

fine cement contains very finer particles than the ordinary Portland cement so it can flow into

very fine and deep cracks in quick time.

7. To Construct Cement Concrete Roads

Cement concrete roads are more famous as high standard roads which are stronger than all

other types of roads. They are also called as rigid pavements because of their rigid nature.

C.C roads have long life span even without proper maintenance. Load wise also they are

much capable than all other types.

8. To Manufacture Precast Members



Many precast members are made using cement as binding material. Cement concrete pipes

are widely used as drains, pipes under culverts etc. Cement concrete brick masonry is more

famous because of the size of block, ease of construction and strength etc.

Water tanks and septic tanks are generally constructed by cement concrete rings. Many other

things like garden seats, flower pots, dust bins, lam posts etc. are manufactured using cement.

9. For Aesthetic Structures

Now a days cement is available in many colors. This is done by adding coloring agent while

manufacturing cement but the percentage of coloring agent should be below 10%. Some of

the coloring agents are iron oxide which gives red or brown, cobalt which gives blue etc.

The colored cement makes the structure beautiful without any painting. Colored cements

generally used for floor finishing, stair treads, window sill slabs, external wall surfaces etc..

Concrete-Concrete is a construction material composed of cement, fine aggregates (sand)

and coarse aggregates mixed with water which hardens with time. Portland cement is the

commonly used type of cement for production of concrete

Quality of mixing water in concrete-The common specifications regarding quality of

mixing water is water should be fit for drinking. Such water should have inorganic solid less

than 1000 ppm. This content lead to a solid quantity 0.05% of mass of cement when w/c ratio

is provided 0.5 resulting small effect on strength.

Workability of concrete-Workability of concrete is the property of freshly mixed concrete

which determines the ease and homogeneity with which it can be mixed, placed, consolidated

and finished’ as defined by ACI Standard 116R-90 (ACI 1990b). The workability of concrete

depends on many factors which are explained in factors affecting workability of concrete.

Water cement ratio has much effect in the workability. Workability is directly proportional to

water cement ratio. An increase in water-cement ratio increases the workability of concrete.

Types of Workability of Concrete

Workability of concrete can be divided into following three types:

1. Unworkable Concrete

2. Medium Workable

3. Highly Workable Concrete

1. Unworkable Concrete – Harsh Concrete

An unworkable concrete can also be called as harsh concrete. It is a concrete with very little

amount of water. The hand mixing of such concrete is not easy.

Such type of concrete has high segregation of aggregates as cement paste is not lubricated

properly to stick to the aggregates. It is very difficult to maintain the homogeneity of concrete

mix and compaction of concrete requires much effort. Water cement ratio of such concrete is

below 0.4.

2. Medium Workable Concrete

This type of concrete workability is used in most of the construction works. This concrete is

relatively easy to mix, transport, place and compact without much segregation and loss of

homogeneity.

This type of concrete workability is generally used in all concrete construction with light

reinforcement (spacing of reinforcement is which allows the concrete to be compacted

effectively). Water cement ratio for medium workable concrete is 0.4 to 0.55.

https://theconstructor.org/concrete/factors-affecting-workability-concrete/11190/



3. Highly Workable Concrete

A highly workable concrete is very easy to mix, transport, place and compact in structures.

Such concrete is used where effective compaction of concrete is not possible or in mass

concrete. Such concrete flow easily and settle down without much effort. But there is high

chances of segregation and loss of homogeneity in this case.

The coarse aggregates tend to settle at the bottom and the concrete paste comes up. Such

concrete is used in case of heavy reinforcement is used where vibration of concrete is not

possible. Example of highly workable concrete is self-compacting concrete. Water cement

ratio of such concrete is more than 0.55.

Workability requirement of concrete varies with each type of construction and compaction

method used. For example, concrete workability required for a slab construction can be same

as a mass concrete footing construction.

Workability requirement when vibrators are used for construction are different from when

vibrators are not used. Similarly, concrete workability used in thick section is not workable

when used in thin sections.

Factors Affecting Workability of Concrete

The workability requirements for a concrete construction depends on:

• Water cement ratio

• Type of construction work

• Method of mixing concrete

• Thickness of concrete section

• Extent of reinforcement

• Method of compaction

• Distance of transporting

• Method of placement

• Environmental condition

Workability Vs. Strength of Concrete

The following figure explains the relation between workability and compressive strength of

concrete: the strength of concrete decreases with increase in water cement ratio. The increase

in water cement ratio indicates increase in workability of concrete. Thus, the strength of

concrete inversely proportional to the workability of concrete.

The reason for this relation is that water from the concrete dries up and leaves voids when

setting of concrete occurs. The more the water is, the more will be the number of voids. Thus,

increase in number of voids decreases the compressive strength of concrete. Thus it is

important to balance the strength and workability requirement for concrete work.

The workability of concrete can be enhanced by use of rounded aggregates and by the use of

workability enhancing admixtures. With the use of admixture such as air-entraining

admixtures, the workability in increased without increase in water-cement ratio. This helps in

attaining required strength and workability for concrete work.

Tests for Workability of Concrete

Tests for Workability of Concrete

Workability of concrete mixture is measured by:

a) Vee-bee consistometer test



b) Compaction factor test

c) Slump test

The first two tests are laboratory tests while the third test is the field test.

Concrete Slump Test

This test is carried out with a mould called slump cone whose top diameter is 10cm, bottom

diameter is 20 cm and height is 30 cm. the test may be performed in the following steps:

1. Place the slump mould on a smooth flat and non-absorbent surface.

2. Mix the dry ingredients of the concrete thoroughly till a uniform colour is obtained and

then add the required quantity of water.

3. Place the mixed concrete in the mould to about one-fourth of its height.

4. Compact the concrete 25 times with the help of a tamping rod uniformly all over the area.

5. Place the concrete in the mould about half of its height and compact it again.

6. Place the concrete up to its three fourth height and then up to its top. Compact each layer

25 times with the help of tamping rod uniformly. For the second subsequent layers, the

tamping rod should penetrate into underlying layers.

7. Strike off the top surface of mould with a trowel or tamping rod so that the mould is filled

to its top.

8. Remove the mould immediately, ensuring its movement in vertical direction.

9. When the settlement of concrete stops, measure the subsidence of the concrete in

millimeters which is the required slump of the concrete.

Suitability of Slump Test:

The slump test is suitable only for the concrete of high or medium workability.

Recommended Values of Concrete Slump Tests for Various Purposes:

No.

Types of concrete

Slump

1

Concrete for road construction

20 to 40 mm

2

Concrete for tops of curbs, parapets, piers, slabs and wall

40 to 50 mm

3

Concrete for canal lining

70 to 80 mm

4

Normal RCC work

80 to 150 mm

5

Mass concrete

20 to 50 mm

6

Concrete to be vibrated

10 to 25 mm

Compaction of concrete-Compaction is the process which expels entrapped air from freshly

placed concrete and packs the aggregate particles together so as to increase the density

of concrete. It increases significantly the ultimate strength of concrete and enhances the bond

with reinforcement.

https://theconstructor.org/concrete/compaction-factor-test/1565/

https://theconstructor.org/concrete/slump-test/1558/



Concrete Mix Design

Concrete mix design is the process of finding right proportions of cement, sand and

aggregates for concrete to achieve target strength in structures. So, concrete mix design can

be stated as Concrete Mix = Cement:Sand:Aggregates. The concrete mix design involves

various steps, calculations and laboratory testing to find right mix proportions. This process is

usually adopted for structures which requires higher grades of concrete such as M25 and

above and large construction projects where quantity of concrete consumption is huge..

Benefits of concrete mix design is that it provides the right proportions of materials, thus

making the concrete construction economical in achieving required strength of structural

members. As, the quantity of concrete required for large constructions are huge, economy in

quantity of materials such as cement makes the project construction economical.

Concrete Mix design of M20, M25, M30 and higher grade of concrete can be calculated from

example below.

Grades of Concrete, Their Strength

Grade of concrete is defined as the minimum strength the concrete must posses after 28 days

of construction with proper quality control. Grade of concrete is denoted by prefixing M to

the desired strength in MPa. For example, for a grade of concrete with 20 MPa strength, it

will be denoted by M20, where M stands for Mix. These grade of concrete is converted into

various mix proportions. For example, for M20 concrete, mix proportion will be 1:1.5:3 for

cement:sand:coarse aggregates.

Regular Grades of Concrete and their Uses

Regular grades of concrete are M15, M20, M25 etc. For plain cement concrete works,

generally M15 is used. For reinforced concrete construction minimum M20 grade of concrete

are used.

Concrete Grade Mix Ratio

Compressive Strength

MPa (N/mm2) Psi

Normal Grade of Concrete

M5 1 : 5 : 10 5 MPa 725 psi

M7.5 1 : 4 : 8 7.5 MPa 1087 psi

M10 1 : 3 : 6 10 MPa 1450 psi

M15 1 : 2 : 4 15 MPa 2175 psi

M20 1 : 1.5 : 3 20 MPa 2900 psi

Standard Grade of Concrete

M25 1 : 1 : 2 25 MPa 3625 psi



M30 Design Mix 30 MPa 4350 psi




High Strength Concrete Grades






What is RCC?

RCC means Reinforced Cement Concrete, i.e., cement concrete reinforced with steel bars,

steel plates, steel mesh etc to increase the tension withstanding capacity of the structure.

Cement Concrete can take up immense compression but weak in tension whereas steel is

good in withstanding both tension and compression.

Here are some of the advantages of RCC construction:

1. Materials used in RCC construction are easily available.

2. It is durable and long lasting.

3. It is fire resisting and not attacked by termites.

4. It is economical in ultimate cost.

5. The reinforced concrete member can be cast to any shape because of the fluidity of

concrete.

6. Its monolithic character gives much rigidity to the structure.

7. Cost of maintenance is nil.

Here are some of its disadvantages:

1. Scrap value of reinforced members is almost nil.

2. Constant checking is required.

3. Skilled labour is engaged in the work.

4. The advantages of RCC outweigh its disadvantages.

This is one construction technique that made construction very easy and brought a boom to

the field of construction.



What is Prestressed Concrete?

Prestressed concrete is a system into which internal stresses are deliberately induced without

any form of external loads to improve its performance. The internal stresses induced in the

concrete structure is used to counteract the stresses coming from the external load

application.

Need for Prestressing Concrete

The need for prestressing in concrete can be justified by the following issue:

1. Concrete is weak in tension and strong in compression. This is a weak point of

concrete that results in early flexural cracks mainly in flexural members like beams

and slabs. To prevent this, the concrete is induced with compressive stress

deliberately (prestressing) and this stress counteracts with the tensile stress the

structure is subjected to during service condition. Hence the chances of flexural

cracks are reduced.

2. The pre-compression that is induced as a part of prestressing helps to enhance the

bending capacity, the shear capacity and the torsional capacity of the flexural

members.

3. A compressive prestressing force can be applied concentrically or eccentrically in the

longitudinal direction of the member. This prevents cracks at critical midspan and

supports at service load.

4. A prestressed concrete section behaves elastically.

5. The full capacity of the concrete in compression can be used over entire depth under

full loading in the case of prestressed concrete.

Advantages of Prestressed Concrete

The major advantages of Prestressed Concrete are:

1. The prestressing of concrete by using high tensile steel improve the efficiency of the

materials

2. The prestressing system works for a span greater than 35m.

3. Prestressing enhance shear strength and fatigue resistance of concrete

4. Dense concrete is provided by prestressing systems thus improving the durability

5. Best choice for the construction of sleek and slender structures.

6. Prestressing helps to reduce the dead load of the concrete structure

7. Prestressed concrete remains uncracked even at service load conditions which proves

the structural efficiency

8. Composite construction by using the prestressed concrete unit and cast-in-unit derives

the economical structure

Disadvantages of Prestressed Concrete

1. Higher material costs

2. Prestressing is an added cost

3. Formwork is more complex than for RC (flanged sections, thin webs) – thus, precast

not as ductile as RCC



Types of steels used in construction

1. Structural Steel. Structural steel is durable and strong. ...

2. Rebar Steel. This steel is also known as reinforcing steel.

3. Alloy Steel. ...

4. Mild Steel. ...

5. Stainless Steel. ...

6. Tool Steel. ...

7. Light Gauge Steel.

Components of a Building Structure

The basic components of a building structure are the foundation, floors, walls, beams,

columns, roof, stair, etc. These elements serve the purpose of supporting, enclosing and

protecting the building structure.

1. Roof

2. Parapet

3. Lintels

4. Beams

5. Columns

6. Damp proof course (DPC)

7. Walls

8. Floor

9. Stairs

10. Plinth Beam

11. Foundation

12. Plinth

1. Roof

The roof forms the topmost component of a building structure. It covers the top face of the

building. Roofs can be either flat or sloped based on the location and weather conditions of

the area.

2. Parapet

Parapets are short walls extended above the roof slab. Parapets are installed for flat roofs. It

acts as a safety wall for people using the roof.

3. Lintels

Lintels are constructed above the wall openings like doors, windows, etc. These structures

support the weight of the wall coming over the opening. Normally, lintels are constructed by

reinforced cement concrete. In residential buildings, lintels can be either constructed from

concrete or from bricks.

4. Beams and slabs

Beams and slabs form the horizontal members in a building. For a single storey building, the

top slab forms the roof. In case of a multi-storey building, the beam transfers the load coming

from the floor above the slab which is in turn transferred to the columns. Beams and slabs are

constructed by reinforced cement concrete (R.C.C).



5. Columns

Columns are vertical members constructed above the ground level. Columns can be of two

types: Architectural columns and structural columns. Architectural columns are constructed

to improve the building’s aesthetics while a structural column takes the load coming from the

slab above and transfers safely to the foundation.

6. Damp Proof Course(DPC)

DPC is a layer of waterproofing material applied on the basement level to prevent the rise of

surface water into the walls. The walls are constructed over the DPC.

Read More: Damp Proof Course (DPC)

7. Walls

Walls are vertical elements which support the roof. It can be made from stones, bricks,

concrete blocks, etc. Walls provide an enclosure and protect against wind, sunshine, rain etc.

Openings are provided in the walls for ventilation and access to the building.

8. Floors

The floor is the surface laid on the plinth level. Flooring can be done by a variety of materials

like tiles, granites, marbles, concrete, etc. Before flooring, the ground has to be properly

compacted and leveled.

9. Stairs

A stair is a sequence of steps that connects different floors in a building structure. The space

occupied by a stair is called as the stairway. There are different types of stairs like a wooden

stair, R.C.C stair etc.

10. Plinth Beam

Plinth beam is a beam structure constructed either at or above the ground level to take up the

load of the wall coming over it.

11. Plinth

The plinth is constructed above the ground level. It is a cement-mortar layer lying between

the substructure and the superstructure.

12. Foundation

The Foundation is a structural unit that uniformly distributes the load from the superstructure

to the underlying soil. This is the first structural unit to be constructed for any building

construction. A good foundation prevents settlement of the building.

Mortar-It is a workable paste which dries to bind building blocks such as stones, bricks, and

concrete masonry units, to fill and seal the irregular gaps between .

Some of the numerous functions of mortar in construction are given below.

1. Mortar is used to bind together the bricks or stones in brick or stone masonry.

2. It is used to give a soft even bed between different layers of brick or stone masonry

for equal distribution of pressure over the bed.

3. It is used to fill up the spaces between bricks or stones for making walls tight.

4. It is used in concrete as a matrix.

5. It is used in plastering works to hide the joints and to improve appearance.

6. It is used for molding and ornamental purpose.

https://theconstructor.org/building/damp-proof-course-dpc/4590/

https://civiltoday.com/civil-engineering-materials/mortar/66-what-is-mortar-mix-definition

https://civiltoday.com/civil-engineering-materials/brick/37-brick-use-construction



Stone Masonry Construction – Materials and Classification

Stone masonry is a type of building masonry construction that uses stones and mortar. This

construction technique is used for building foundations, floors, retaining walls, arches, walls

and columns. The stones used for masonry construction are natural rocks. These natural rocks

are cut and dressed into proper shape in order to use it in masonry construction. Stones are

one of the most durable and strong building materials.

Materials Used for Stone Masonry

The materials used for stone masonry are:

1. Stones

2. Mortar

1. Stones

The stones used for masonry construction must be hard, tough and free from cracks, sand

holes, and cavities. The selection of stone for particular work is dependent on the availability

of the stone and the importance of the structure. The common stones used for masonry

construction are limestone, sandstone, granite, marble, laterite, etc.

2. Mortar

The binding material used for masonry construction is the mortar. Cement or lime with sand

and water form the mix for masonry mortar. The mix formed is uniform in nature. The two

main factors affecting the selection of mortar for masonry are:

• Strength required

• Colour of the stone

• The loads coming on the structure

Classification of Stone Masonry

The two main classifications of Stone Masonry are:

1. Rubble Masonry

2. Ashlar Masonry

1. Rubble Masonry

This is the stone masonry type where stones employed are either undressed or roughly

dressed. These masonry constructions do not have a uniform thickness. The strength of the

rubble masonry is dependent on the:

• Quality of Mortar Used

• Use of Long through stones

• Proper filling of mortar between the stone spaces and joints

Rubble masonry can be again classified into

a. Coursed Rubble Masonry

b. Uncoursed Rubble Masonry

c. Dry Rubble Masonry

d. Polygonal Masonry

e. Flint Masonry



a. Coursed Rubble Masonry

In coursed rubble masonry construction, the stones in a particular course are in equal heights.

The stones hence used possess different sizes. In this type, all the courses do not have same

height. This type is commonly employed in the construction of public buildings, abutments,

residential buildings and piers of ordinary bridges.

.

Fig.1. Coursed Rubble Masonry

b. Uncoursed Rubble Masonry

An uncoursed rubble masonry is the cheapest and roughest form of stone masonry

construction. These construction use stones of varied shape and size. The stones are directly

taken from the quarry called as undressed stone blocks. The courses is not maintained

regulary in this method of construction. Initially larger stones are laid first. The spaces

between them are filled with spalls or sneeks. This is divided into two types:

• Random Uncoursed Rubble Masonry

• Square Uncoursed Rubble Masonry

Random Uncoursed Rubble Masonry: In this type, the weak corners and edges of the stone

are removed with the help of a mason’s hammer. At the quoins and jambs, bigger stones are

employed in order to increase the strength of the masonry.



Fig.2. Random Uncoursed Rubble Masonry

Square Uncoursed Rubble Masonry: Here, the stones are made roughly square shape and

used in construction. The facing stones are provided a hammer-dressed finish. Larger stones

are used as quoins. Chips are not used as bedding.

Fig.3. Square Uncoursed

Rubble Masonry

c. Polygonal Rubble Masonry

Here, the stones for masonry are roughly shaped into irregular polygons. The stones are then

arranged in such a way that it avoids vertical joints in the face work. Break the joints as

possible. Use of stone chips to support the stones.



Fig.4.

Polygonal Rubble Masonry

d. Flint Rubble Masonry

In areas where flint is available plenty, a flint rubble masonry is employed. Flints are

irregularly shaped nodules of silica. They are extremely hard but brittle in nature. The

thickness of the flintstones varies from 8 to 15cm. Their length varies from 15 to 30cm.

e. Dry Rubble Masonry

These are rubble masonry construction performed without the use of mortar. Small spaces are

filled with smaller stone pieces. It is used in pitching the earthen dams and the canal slopes.

Fig.5. Dry Rubble Masonry

2. Ashlar Masonry

Ashlar masonry is constructed using accurately dressed stones that possess uniform and fine

joints. The thickness of the joints ranges about 3mm which is arranged in various patterns.

The size of the stone blocks must be in proportion with the thickness of the walls.

The various types of ashlar masonry are:



1. Ashlar Fine Masonry

2. Ashlar Block in Course

3. Ashlar Chamfered Masonry

4. Ashlar Rough Tooled Masonry

5. Rock or Quarry Faced Masonry

1. Ashlar Fine Masonry

In ashlar fine masonry construction, each stone is cut into uniform size and shape, almost

rectangular in shape. This shape hence provides perfect horizontal and vertical joints with the

adjacent stones. An ashlar fine masonry construction is very costly.

2. Ashlar Rough Masonry

This type has stones whose sides are finely chisel -dressed. The face of the stones is made

rough by means of tools. Around the perimeter of the rough dressed face of each stone, a strip

of 25mm width is provided.

Fig.6. Ashlar

Fine and Rough Masonry

3. Rock and Quarry Faced

This masonry type has a 25 mm wide strip made by a chisel placed around the perimeter of

every stone. The remaining portion of the face is left in the same form as it is received.

4. Ashlar Block in Course Masonry

This type is a combination of ashlar masonry and rubble masonry. The faces work of the

masonry stones is either rough tooled or hammer dressed stones. The backing of the wall may

be done in rubble masonry.



Fig.7. Ashlar Rock and

Ashlar Block Course Masonry

5. Ashlar Chamfered Masonry

A strip is provided as shown in the figure below. But the sides are chamfered or beveled at an

angle of 45 degrees by means of a chisel at a depth of 25mm.

Fig.8. Ashlar Chamfered Masonry

Brick Masonry

Brick masonry is a highly durable form of construction. It is built by placing bricks in mortar

in a systematic manner to construct solid mass that withstand exerted loads. There are several

types of bricks and number of mortars which can be used to construct brick masonry. The

bond in brick masonry, which adheres bricks together, is produced by filling joints between

bricks with suitable mortar. Special cautions shall be practiced while mortar is mixed and

placed since it greatly affect the performance and durability of masonry structure.

The most commonly used types of bonds in brick masonry are:

1. Stretcher bond

2. Header bond

3. English bond and

4. Flemish bond



1. Stretcher bond

Longer narrow face of the brick is called as stretcher as shown in the elevation of figure

below. Stretcher bond, also called as running bond, is created when bricks are laid with only

their stretchers showing, overlapping midway with the courses of bricks below and above.

Stretcher bond in the brick is the simplest repeating pattern. But the limitation of stretcher

bond is that it cannot make effective bonding with adjacent bricks in full width thick brick

walls. They are suitably used only for one-half brick thick walls such as for the construction

half brick thick partition wall.

Walls constructed with stretcher bonds are not stable enough to stand alone in case of longer

span and height. Thus they Then need supporting structure such as brick masonry columns at

regular intervals.

Stretcher bonds are commonly used in the steel or reinforced concrete framed structures as

the outer facing. These are also used as the outer facing of cavity walls. Other common

applications of such walls are the boundary walls, gardens etc.

2. Header bond

Header is the shorter square face of the brick which measures 9cm x 9cm. Header bond is

also known as heading bond. In header bonds, all bricks in each course are placed as headers

on the faces of the walls. While Stretcher bond is used for the construction of walls of half

brick thickness whereas header bond is used for the construction of walls with full brick

thickness which measures 18cm. In header bonds, the overlap is kept equal to half width of

the brick. To achieve this, three quarter brick bats are used in alternate courses as quoins.



Fig-2: Header Bond

Fig-3: Header Bond Isometric View

3. English Bond

English bond in brick masonry has one course of stretcher only and a course of header above

it, i.e. it has two alternating courses of stretchers and headers. Headers are laid centered on

the stretchers in course below and each alternate row is vertically aligned.

To break the continuity of vertical joints, quoin closer is used in the beginning and end of a

wall after first header. A quoin close is a brick cut lengthwise into two halves and used at

corners in brick walls.

Fig-4: English Bond



Fig-4: English Bond – Isometric View

4. Flemish Bond

For the breaking of vertical joints in the successive courses, closers are inserted in alternate

courses next to the quoin header. In walls having their thickness equal to odd number of half

bricks, bats are essentially used to achieve the bond.

Flemish bond, also known as Dutch bond, is created by laying alternate headers and

stretchers in a single course. The next course of brick is laid such that header lies in the

middle of the stretcher in the course below, i.e. the alternate headers of each course are

centered on the stretcher of course below. Every alternate course of Flemish bond starts with

header at the corner.

The thickness of Flemish bond is minimum one full brick. The disadvantage of using Flemish

bond is that construction of Flemish bond is difficult and requires greater skill to lay it

properly as all vertical mortar joints need to be aligned vertically for best effects. For the

breaking of vertical joints in the successive courses, closers are inserted in alternate courses

next to the quoin header. In walls having their thickness equal to odd number of half bricks,

bats are used to achieve the bond.

Flemish bonds have better appearance but are weaker than English bonds for load bearing

wall construction. Thus, if the pointing has to be done for brick masonry walls, then Flemish

bond may be used for better aesthetic view. If the walls have to be plastered, then it is better

to use English bond.



Fig-5: Flemish Bond

Fig-6: Flemish Bond Front Appearance



Flemish bonds are classified as:

• Single Flemish Bond

• Double Flemish Bond

Single Flemish bond is a combination of English bond and Flemish bond. In this type of

construction, the front exposed surface of wall consists of Flemish bond and the back surface

of the wall consists of English bond in each course. Minimum thickness required for single

Flemish bond is one and a half brick thickness. The main purpose of using single Flemish

bond is to provide greater aesthetic appearance on the front surface with required strength in

the brickwork with English bond.

Double Flemish Bond has the same appearance both in the front and back elevations, i.e. each

course consists of alternate header and stretcher. This type of bonding is comparatively

weaker than English bond.

Roof

A roof is the top covering of a building, including all materials and constructions necessary to

support it on the walls of the building or on uprights; it provides protection against rain,

snow, sunlight, extremes of temperature, and wind. A roof is part of the building envelope.

Floor

A floor is the bottom surface of a room or vehicle. Floors vary from simple dirt in a cave to

many-layered surfaces made with modern technology. Floors may be stone, wood, bamboo,

metal or any other material that can support the expected load.

SURVEYING

Surveying is the science and art of making all essential measurements to determine the

relative position of points or physical and cultural details above, on, or beneath the surface of

the Earth, and to depict them in a usable form, or to establish the position of points or details.

Linear Measurements in Surveying

Linear measurements in surveying can be performed by mainly three methods namely direct

method, electromagnetic methods and optical methods. The direct method is the common

method that employs a chain, tape or any other instrument to measure the linear distance.

Various methods coming under the direct method of linear measurement are:

1. Linear Measurement by Pacing

2. Linear Measurement by Passometer

3. Linear Measurement by Pedometer

4. Linear Measurement by Odometer and speedometer

5. Linear Measurement by Chaining

1. Pacing

The pacing technique is mostly employed in preliminary surveys and explorations. In this

method, the surveyor is required to conduct a rough survey quickly. This also roughly check

the distance measured by other means.



Fig,1. Pacing in Surveying

In this method, the number of paces between the two points of the line is counted. Knowing

the average length of the pace helps to know the length of the line. The length of the pace is

dependent on the person who is measuring, the ground, the speed of pacing and the slope of

the country.

By walking on an approximate level ground over various lines of known lengths helps to

determine the length of one’s natural step. Performing pacing over rough ground or on slopes

is a difficult process.

2. Passometer

The passometer is a watch like instrument that is carried on the person’s pocket or tied on the

man’s leg. This instrument records the paces when the man moves from one point to another.

Fig.2. Passometer

This technique hence overcomes the monotony and strain in counting the paces by the

surveyor. The distance is calculated as the product of the number of paces and the average

length of the pace.

3. Pedometer

Pedometer is a similar device like passometer that automatically measures the distance. A

pedometer is best in measuring the vertical distances.



Fig.3. Pedometer

4. Odometer

Odometer is an instrument that measures the number of revolutions of a wheel. The number

of revolutions taken to cover the length multiplied by the circumference of the wheel gives

the value of the distance covered.

Fig.4. Odometer in Surveying

This instrument does not provide accurate results on an undulating surface. When the surface

is smooth, the speedometer used in the vehicles can be used.

5. Chaining

Chaining method determines the distance by means of a tape or a chain. This is one of the

accurate methods to determine the linear measurements. The chain is used for ordinary

precision. Tape or a special bar is used to measure distance with high precision.

Chain Survey

Chain surveying is considered to be the simplest method of surveying in which measurements

are taken in the field and other supplementary works like plotting calculations are carried out

in office. The measurements in chain surveying are linear- angular measurements are not

considered.



Moreover, it provides fairly accurate result provided that the work is conducted carefully.

Chain surveying is suitable for small areas with few details. Tools and equipments required

include chain, tape, ranging rod, arrows and, sometimes, a cross staff.

In this type of surveying, survey stations (main stations, tie or subsidiary stations) shall be

specified carefully otherwise the outcome of the surveying process may not be accurate.

Applicability of Chain Survey

Obviously, chain surveying cannot be used in all cases. It can be used if the area under

consideration meets the following conditions:

1. The area shall be fairly small.

2. The ground is moderately levelled.

3. The area needs to be open.

4. The ground has few and simple details.

Fig. 1: Chain Surveying

Chain Survey Tools

1. Chain

2. Tape

3. Ranging-Rod

4. Arrows

5. Cross staff



Fig. 2: Ranging Rod

Fig. 3: Pegs in Chain Surveying

Chain Survey Stations

Survey stations are points of importance at the beginning and end of a chain line. There are

two major types of stations in chain surveying:

1. Main stations

Main stations are the end of lines that determine the boundary of the surveying.

2. Tie (Subsidiary) Stations

Tie stations are points which are specified on the chain line (main survey lines) where it is

required to identify interior details like buildings and fences.

Factors Affecting Survey Station Selection

1. Stations should be visible from at least two or more stations.

2. As far as possible, main lines should run on level ground.

3. All triangle shall be defined properly (No angle less than 30º).

4. Each triangle should have at least one check line.

5. Survey lines should be as few as possible.

6. Obstacles to ranging and chaining should be avoided.

7. Sides of the larger triangles should pass as close to the boundary lines as possible.

8. Trespassing and frequent crossing of the roads should be avoided.

Line Types in Chain Survey

1. Base Lines



It is the main and longest line from which all measurements to demonstrate details of the

work are taken. The base line passes through the center of the field.

2. Chain Line (Main Survey) Lines

The lines that join main stations are termed as chain line or main survey lines.

3. Tie (Subsidiary) Lines

It joins two fixed points on the chain line. The advantage of tie line appears while checking

surveying accuracy in locating interior details such as buildings and paths.

4. Check (Proof) Lines

It joins triangle apex to some fixed points on any two sides of a triangle. It is used to examine

the accuracy of the framework. The length of check line measured on ground shall be

consistent with its length on the plan.

Fig. 4: Types of Lines in

Chain Surveying

Offsets in Chain Survey

Lateral measurements from the baseline are termed as offsets. They are used to fix locations

of various objects with respect to the baseline. Commonly, offsets are established at right

angle. There are two major type of offsets, namely: perpendicular offsets and oblique offsets.

Fig. 5: Perpendicular and

Oblique Offset

Chain Survey Procedures

1. Firstly, inspect the area to be surveyed and prepare key plan. This stage is termed as

reconnaissance phase.

2. Then, mark stations using suitable means such as fixing ranging poles, driving pegs,

and digging and fixing a stone.



3. After that, specify the way for passing the main line which should go through the

center of the field.

4. Fix ranging road on stations

5. Then, the chaining can begin.

6. Make ranging wherever necessary.

7. Measure the change and offset and record them.

Fig. 6: Chain Surveying- Procedure

Types of Chains used in Surveying, Their Parts, Testing and Advantages

Chains are the measuring instrument used in surveying formed by the 100 links of 4mm

galvanized mild steel wire. These links are joined by 3 circular or oval wire rings. These rings

provide the flexibility to the chains. Every aspect of the life requires some measuring units.

Measurements are used to do the work precisely and accurately. Let it be from kitchen to

office, everywhere measurements are used. So as in engineering calculation or measurements

holds a very greater role in construction or surveying or any other aspect. There are various

units of measurements such as meters, centimeters, feets, inches, acre, yards and the list goes

on. Same as units there are various instrument used in the measurements of any entity. One of

the instruments used in measurement are chains.

https://theconstructor.org/surveying/



Parts of Chains used in Surveying

The chain consists of many small parts used for handling or reading the measurements.

• At the ends chain is provided with brass handle with swivel joint so that it can be easy

to roll or unroll the chain without twisting and knots.

• At every 10th link is provided with a tally of one teeth, 20th link with a tally of two

teeth and so on till 40th link. This is provided for the easy reading of measurements.

• At the center of the chain is provided with a circular talley used for easy reading.



Types of Chains used in Surveying

Depending upon the length of the chain, these are divide into following types,

1. Metric chains

2. Steel band or Band chain

3. Gunter’s chain or surveyor’s chain

4. Engineer’s chain

5. Revenue chain

A. Metric chains

Metric chains are the most commonly used chain in India. These types of chains comes in

many lengths such as 5, 10, 20 and 30 meters. Most commonly used is 20m chain. Tallies are

provided at every 2m of the chain for quick reading. Every link of this type of chain is 0.2m.

The total length of the chain is marked on the brass handle at the ends.

B. Steel band or Band chain

These types of chain consist of a long narrow strip of steel of uniform width of 12 to 16 mm

and thickness of 0.3 to 0.6 mm. this chain is divides by brass studs at every 20cm or instead

of brass studs, band chain may have graduated engraving as centimeter.

For easy use and workability band chains are wound on steel crosses or metal reels from

which they can be easily unrolled. These steel bands are available in 20m and 30m length and

the width of about 12-16mm.

C. Gunter’s chain or surveyor’s chain

Gunter chain comes in standard 66ft. These chain consists of 100links, each link being 0.66ft

or 7.92inches. The length 66ft is selected because it is convenient in land measurements.

10 square Gunter’s chains = 1 Acre

10 Gunter chains = 1 Furlong

80 Gunter chains = 1 mile

D. Engineer’s chain



This chain comes in 100ft length. Its consist of 100 links each link being 1ft long. At every

10 links a brass ring or tags are provided for indication of 10 links. Readings are taken in feet

and decimal.

E. Revenue Chain

The standard size of this type of chain is 33ft. The number of links are 16, each link being

2 ft. This chain is commonly used in cadastral survey.

Testing and Adjustment of Chain

As the chain is a metal made, it may undergo many changes due to temperature effect or

human error and etc. So for all lengths of chain a tolerance is given,

5m chain = + or – 3mm




Chain length shorten due to

1. Bending of links.

2. Sticking of mud in the rings

Chain length increases due to

• Opening of small rings.

• Wearing of surfaces.

Chains may be tested with respect to

• Steel tape

• Permanent test gauge

• Pegs driven in the field at required distances

• Permanent test gauge made with dressed stones

If chain is found long, then

• Close the joins of the rings

• Reshape the elongated rings

• Remove one or two rings

• Replace worn out rings

If chain is found short, then

• Straighten the links

• Replace the small rings with big one

• Insert additional rings

• Flattening the circular rings

Errors in chain Surveying

Errors in chaining may be classified as:

• Personal errors



• Compensating errors, and

• Cumulating errors.

Personal Errors

Wrong reading, wrong recording, reading from wrong end of chain

etc., are personal errors. These errors are serious errors and cannot be detected easily. Care

should be taken to avoid such errors.

Compensating Errors

These errors may be sometimes positive and sometimes negative. Hence

They are likely to get compensated when large number of readings are taken. The magnitude

of such errors can be estimated by theory of probability. The following are the examples of

such errors:

• Incorrect marking of the end of a chain.

• Fractional part of chain may not be correct though total length is corrected.

• Graduations in tape may not be exactly same throughout.

• In the method of stepping while measuring sloping ground, plumbing may be crude.

Cumulative Errors

The errors that occur always in the same direction are called cumulative errors. In each

reading the error may be small, but when large number of measurements are made they may

be considerable, since the error is always on one side. Examples of such errors are:

1. Bad ranging

2. Bad straightening

3. Erroneous length of chain

4. Temperature variation

5. Variation in applied pull

6. Non-horizontality

7. Sag in the chain, if suspended for measuring horizontal distance on a sloping ground.

Errors (i), (ii), (vi) and (vii) are always +ve since they make measured length more than

actual.

Advantages and Disadvantages of Chains in Surveying

Advantages of Chains in Surveying

• Chain survey is simplest and commonest method used in surveying exercises

• The equipment used to conduct chain survey are simple to use,

• The equipment used in chain survey can easily be replaced. For example measuring

rods can be replaced with measuring tape.

• This method does not involve complicated mathematical calculation. I know this is

the relief to those who are afraid of mathematics

• In chain survey few people are needed to conduct the survey. Normally chain survey

team has three people Booker, leader and follower.

Disadvantages of Chains in Surveying

• Simple chain survey cannot be conducted in built up areas and large areas.



• Simple chain survey is subject to several chances of errors of accumulation which

may cause by problem of chain. The chain linkage may fail to stretch up properly and

result in inaccurate data. Also clogging of chain may read to error in reading.

• It is time consuming

• It may not be conducted in areas with steep slopes or water logged areas. Chain

survey is usually conducted in dry areas with gentle slopes. It becomes more

complicated when survey is conducted in areas that are too wet.

• Chain survey becomes more complicated method when there are raised points

(obstacles) in between areas to be surveyed

Types of Tapes Used in Surveying

Tapes are used in surveying to take linear measurements. They are available in different

lengths and can be made of different materials. The 5 most common types of tapes used in

surveying are discussed in this article.

Types of Tapes Used in Surveying

There are 5 types of tapes available in surveying for linear measurements and they are as

follows :

1. Linen Tape

2. Woven Metallic Tape

3. Steel Tape

4. Synthetic Tape

5. Invar Tape

1. Linen Tape

Linen tape, also known as cloth tape is a varnished strip made of closely woven linen. The

width of the strip is about 12 to 16 mm. It is available in different lengths such as 10m, 20m,

30m, and 50m. Both ends of the linen tape are provided with metallic handles and the whole

tape is wounded in leather or metal case.



Fig 1: Cloth Tape

Linen tapes are light in weight and easy to handle. These tapes may shrink when exposed to

water and also elongate when pulled. Hence, these tapes are not suitable for accurate

surveying measurements. These are generally used for measuring offsets and for ordinary

works.

2. Woven Metallic Tape

The metallic woven tape is an improved version of linen tape. Brass or copper made wires are

used as reinforcement for the linen material. Hence, it is more durable than normal linen tape.

A brass ring is provided at the end of the tape which is included in the length of the tape.

Fig 2:

Woven Metallic Tape ( Metal wires reinforcement can be seen in close look)

These tapes are available in different lengths of 2m, 10m, 15m, 20m, 30m, and 50m. These

are used for survey works such as topographical survey works where minor errors are not

taken into consideration.

3. Steel Tape



A steel tape is made of steel or stainless steel. It consists of a steel strip of 6mm to 16mm

wide. It is available in lengths of 1m, 5m, 8m, 10m, 20m, 30m and 50m. Meters, decimeters,

and centimeters are graduated in the steel strip. Steel tapes generally came up with the metal

case with automatic winding device. The tape is withdrawn from the case by using a hand

during measuring and it is rewound into the case by just pressing button provided on the case.

Fig 3: Steel Tape

Steel tapes are not flexible and are suitable for measuring leveled surfaces only. They may

corrode easily when exposed to moisture and to prevent this tape, it should be cleaned and

oiled after every use. These tapes are generally used for standardizing chains, measurements

of constriction works, etc.

4. Synthetic Tape

Synthetic tapes are made of glass fibers coated with PVC. These are light in weight and

flexible. They are available in lengths of 5m, 10m, 20m, 30m, and 50m. Synthetic tapes may

stretch when subjected to tension. Hence, these are not suitable for accurate surveying works.

However, synthetic tapes are recommended in place of steel tapes where it is essential to take

measurements in the vicinity of electric fences and railway lines, etc.

5. Invar Tape

Invar tapes are made of an alloy which consists of 36% of nickel and 64% of steel. Invar tape

contains a 6mm wide strip and is available in different lengths of 30m, 50m, 100m.

The coefficient of thermal expansion of invar alloy is very low. It is not affected by changes

in temperature. Hence, these tapes are used for high precision works in surveying such as

baseline measurement, triangulation surveys, etc. Invar tapes are expensive than all the other

types of tapes. These tapes should be handled with care otherwise bends or kinks may be

formed.



Fig 5: Invar Tape

Ranging

The process of fixing or establishing intermediate points to facilitate measurement of the

survey lines are called as Ranging. The intermediate points are located by means of ranging

rodes, offset rods and ranging poles.

Ranging Out Survey Lines

While measuring the survey lines, the chain or the tape has to be stretched along the survey

line along that joins two terminal stations. When the line to be measured has a smaller length

compared to the chain, then the measurement goes smooth. If the length of the line is greater,

the survey lines have to be divided by certain intermediate points, before conducting the

chaining process. This process is called ranging.

The process of ranging can be done by two methods:

1. Direct Ranging

2. Indirect Ranging

1. Direct Ranging

Direct ranging is the ranging conducted when the intermediate points are intervisible. Direct

ranging can be performed by eye or with the help of an eye instrument.

Ranging by Eye

As shown in figure-1 below, let A and B are the two intervisible points at the ends of the

survey line. The surveyor stands with a ranging rod at the point A by keeping the ranging rod

at the point B. The ranging rod is held at about half metre length.



Fig.1.Direct Ranging

The assistant then takes the ranging rod and establishes at a point in between AB, almost in

line with AB. This is fixed at a distance not greater than one chain length from point A.

The surveyor can give signals to the assistant to move traverse till the rod is in line with A

and B. In this way, other intermediate points are determined.

Ranging by Line Ranger

The figure-2 below shows a line ranger that has either two plane mirror arrangement or two

isosceles prisms that are placed one over the other. The diagonals of the prism are arranged

and silvered such that they reflect incident rays.

Fig.2. Ranging by Line Ranger

In order to handle the instrument in hand a handle with hook is provided. The hook is to

enable a plumb- bob to help transfer the point to the ground.

In order to range the point ‘P’, initially two rods are fixed at points A and B. By eye

judgment, the surveyor holds the ranging rod at P almost in line with AB.

The lower prism abc receives the rays coming from A which is then reflected by the diagonal

ac towards the observer. The upper prism dbc receives the rays from B which is then

reflected by the diagonal bd towards the observer. Hence the observer can see the images of



the ranging rods A and B, which might not be in the same vertical line as shown in figure-

2(c).

The surveyor moves the instrument till the two images come in the same vertical line as

shown in figure-2(d). With the help of a plumb bob, the point P is then transferred to the

ground. This instrument can be used to locate the intermediate points without going to the

other end of the survey line. This method only requires one person to hold the line ranger.

2. Indirect Ranging

Indirect ranging is employed when the two points are not intervisible or the two points are at

a long distance. This may be due to some kind of intervention between the two points. In this

case, the following procedure is followed.

As shown in figure-3, two intermediate points are located M1 and N1 very near to chain line

by judgment such that from M1, both N1 and B are visible & from N1 both M1 and A are

visible.

Fig.3. Indirect

Ranging

At M1 and N1 two surveyors stay with ranging rods. The person standing at M1 directs the

person at N1 to move to a new position N2 as shown in the figure. N2 must be inline with

M1B.

Next, a person at N2 directs the person at M1 to move to a position M2 such that it is inline

with N2A. Hence, the two persons are in points are M2 and N2.

The process is repeated until the points M and N are in the survey line AB. Finally, it reaches

a situation where the person standing at M finds the person standing at N in line with NA and

vice versa. Once M and N are fixed, other points are fixed by direct ranging.



Compass Surveying

A compass surveying is performed by means of a magnetic compass which helps to

determine the angles and the direction of the survey lines. The main two types of magnetic

compass employed are a prismatic compass and a surveyor compass.

Principle of Magnetic Compass

The magnetic bearings of a line can be determined by a magnetic compass. The bearings can

be measured either in the whole bearing system (WBS) or Quadrantal Bearing System (QBS).

This is merely dependent on the type of compass employed for the measurement. When a

narrow strip of steel or iron is magnetized and suspended about its center such that it can

freely oscillate about the vertical axis, then the strip establishes itself in the magnetic

meridian at the place of observation. This is the working principle of a magnetic compass.

Features of a Magnetic Compass

The main features of a Magnetic compass are:

1. Magnetic Needle

2. Line of Sight

3. Graduated Circle

4. Compass Box

The purpose of the magnetic needle is to establish the magnetic meridian. A line of sight

helps to sight the other end of the survey line through the compass. A graduated circle is

employed to read the directions of the lines. It can be attached either to the box or to the

needle. In order to house the above parts, a compass box is used. The whole housing is then

supported by means of a tripod or a suitable stand.

Types of Compass Used in Surveying

The main types of compasses that are used in compass surveying are:

1. Prismatic Compass

2. Surveyor’s Compass

1. Prismatic Compass



Fig.1. The Prismatic Compass

Figure-2 below shows the parts of a prismatic compass. It is one of the most convenient and

portable forms of the magnetic compass. It can be held in hand or in a tripod stand for

carrying out the measurement.

Fig.2. Prismatic

Compass

The line of sight is defined by the object vane and the eye vane. A prismatic compass helps to

conduct both sightings and reading simultaneously. The figure-3 below shows the system of

graduation in a prismatic compass.



Fig.3. System of

Graduation in Prismatic Compass

The compass is initially held over the starting station of the survey line and the adjustments

are provided. The magnetic meridian is thus obtained and then starts to take the

measurements by sighting to the next station. As shown in figure-3 above, the readings

increase in clockwise direction i.e. from the south ( 0 degrees) to West (90 degrees) and

North (180 degrees) and East (270 degrees)

Temporary Adjustments for Prismatic Compass

The temporary adjustments usually followed for prismatic compass are:

1. Centering

2. Levelling

3. Focusing the Prism

1. Centering: In this step, the instrument is kept exactly over the station point. This can be

done either by adjusting the tripod stands or by using a plumb-bob. Sometimes, a pebble can

be freely dropped from this center to the bottom of the instrument to check the centering.

2. Levelling: The instrument must be held such that the graduated disc swings freely and

when viewed from the top edge it must appear level. If it is not used as a hand instrument, a

tripod is used to support the instrument for levelling.

3. Focusing the Prism: Till the readings are observed sharp and clear, the prism attachment

is slid up and down for proper focusing.

2. The Surveyor’s Compass

The figure-4 below shows the sectional view of a surveyor’s compass. It consists of a circular

brass box housing a magnetic needle. This needle swings over a bass circle which is divided

into 360 degrees.



Fig.4. The Surveyor’s

Compass

It consists of a pair of sights which is used to measure the horizontal angle. This is located in

the north-south axis. The surveyor’s compass is usually mounted over a tripod and leveled by

using ball and socket mechanism.

Fig.5. Surveyor’s Compass

The temporary adjustments for the surveyor’s compass are the same as that of the prismatic

compass. The permanent adjustments are sometimes necessary for the surveyor’s compass-

like:

1. Adjustments in Levels



2. Adjustment of needle

3. Adjustment of Sight vanes

4. Adjustment of the Pivot

Fig.6. System

of Graduation in Surveyor’s Compass

Bearing

The whole bearing system (WBS) and Quadrantal Bearing system (QBS) are two notations of

bearings that are used in compass surveying. The WCB system can be converted to QBS or

vice versa by a simple calculation.

Bearing and Angles

A survey line can be measured with relation to another survey line or with relation to the

meridian. The first method gives the angle between the line. The second gives the bearing.

Hence, the bearing can be defined as the direction of the line with respect to the given

meridian.

There are mainly three types of meridian:

1. True meridian

2. Magnetic meridian

3. Arbitrary meridian

1. True Meridian

A line that passes through a point, with a plane passing through the point and the North-south

poles form the true meridian. In other words, it forms the line that passes through the true

north and the south poles.

The true bearing of a given line is the horizontal angle made with the true meridian through

one of the extremities of the line.

2. Magnetic Meridian

The direction that is shown by a freely suspended and floating balanced magnetic needle is

the magnetic meridian. A magnetic compass can be used to determine the magnetic meridian.

The magnetic compass used for this purpose must be free from other attractive forces.

The magnetic bearing of a given line is the horizontal angle that it makes with the magnetic

meridian that is passing through one of the extremities of the line.

3. Arbitrary Meridian



In certain situations, a convenient direction is established with respect to a permanent or a

common mark or a signal in the area, during the survey. These are called arbitrary meridians

which helps to determine the relative positions of the survey line.

The horizontal angle made by a line with the arbitrary meridian passing through one of its

extremities is called as an arbitrary bearing.

Whole Bearing and Quadrantal Bearing Systems

The common bearing designations used in surveying are:

1. Whole Circle Bearing System or Azimuthal System (W.C.B)

2. The Quadrantal Bearing or Reduced Bearing System (QB)

1. Whole Circle Bearing System or Azimuthal System (W.C.B)

A WCB bearing method measures angles from the magnetic north or with the south in the

clockwise direction as shown in figure-1 below.

Fig.1. The Whole Bearing System ( WCB)

Hence, the value of the bearing varies from 0 degrees to 360 degrees. A prismatic compass is

graduated by a WCB system. As shown in the figure above, the WCB of AB, AC, AD, and

AF are Q1, Q2, Q3, and Q4.

2. The Quadrantal Bearing or Reduced Bearing System (QB)

In the QB system, the bearing angle is measured either from North or South whichever is

nearer. This can be measured either in clockwise or anti-clockwise. Here, the quadrant at

which the line lies has to be mentioned.

As shown in figure-2, ‘B’ is the bearing of line AC with the south, which is lying in S-E

Quadrant. Hence, it is represented as S B E. The Q.B lines vary from 0 to 90 degrees.



Fig.2. The Quadrantal Bearing System (QBS)

Local Attraction

Local attraction is an error that is caused either by the influence of magnetic disturbances

around the place of work on the instrument such that it will show wrong results.

for example, magnet present in the calculator can also produce some variation in the needle

of the compass while measuring the angle.

Modern Surveying Instruments and Their Uses

• Electronic Distance Measurement (EDM) Instruments

• Total Station

• Global Positioning System (GPS)

• Automatic Level

1. Electronic Distance Measurement (EDM) Instruments

Direct measurement of distances and their directions can be obtained by using electronic

instruments that rely on propagation, reflection and reception of either light waves or radio

waves. They may be broadly classified into three types:

a. Infrared wave instruments

b. Light wave instruments

c. Microwave instruments

a. Infrared Wave Instruments

These instruments measure distances by using amplitude modulated infrared waves. At the

end of the line, prisms mounted on target are used to reflect the waves. These instruments are

light and economical and can be mounted on theodolites for angular measurements. The

range of such an instrument will be 3 km and the accuracy achieved is ± 10 mm.

E.g. DISTOMAT DI 1000 and DISTOMAT DI 5

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DISTOMAT DI 1000

It is a very small, compact EDM, particularly useful in building construction and other Civil

Engineering works, where distance measurements are less than 500 m. It is an EDM that

makes the meaning tape redundant. To measure the distance, one has to simply point the

instrument to the reflector, touch a key and read the result.

b. Light Wave Instruments

These are the instruments which measures distances based on propagation of modulated light

waves. The accuracy of such an instrument varies from 0.5 to 5 mm / km distance and has a

range of nearly 3 km.

Eg: Geodimeter



Geodimeter

Geodimeter is an instrument which works based on the propagation of modulated light

waves, was developed by E. Bergestand of the Swedish Geological Survey in collaboration

with the manufacturer M/s AGA of Swedish. The instrument is more suitable for night time

observations and requires a prism system at the end of the line for reflecting the waves.

c. Microwave Instruments

These instruments make use of high frequency radio waves. These instruments were

invented as early as 1950 in South Africa by Dr. T.L. Wadley. The range of these

instruments is up to 100 km and can be used both during day and might.

Eg. Tellurometer



Tellurometer

It is an EDM which uses high frequency radio waves (micro-waves) for measuring

distances. It is a highly portable instrument and can be worked with 12 to 24-volt battery.

For measuring distance, two Tellurometers are required, one to be stationed at each end of the

line, with two highly skilled persons, to take observations. One instrument is used as a master

unit and the other as a remote unit.

Just by pressing a button a master can be converted into remote unit and vice-versa. A

speech facility (communication facility) is provided to each operator to interact during

measurement.

Total Station

Total Station is a lightweight, compact and fully integrated electronic instrument combining

the capability of an EDM and an angular measuring instrument such as wild theodolite.

Total Station can perform the following functions:

• Distance measurement

• Angular measurement

• Data processing

• Digital display of point details

• Storing data is an electronic field book



The important features of total station are,

1. Keyboard-control – all the functions are controlled by operating key board.

2. Digital panel – the panel displays the values of distance, angle, height and the

coordinates of the observed point, where the reflector (target) is kept.

3. Remote height object – the heights of some inaccessible objects such as towers can be

read directly. The microprocessor provided in the instrument applies the correction

for earth’s curvature and mean refraction, automatically.

4. Traversing program – the coordinates of the reflector and the angle or bearing on the

reflector can be stored and can be recalled for next set up of instrument.

5. Setting out for distance direction and height -whenever a particular direction and

horizontal distance is to be entered for the purpose of locating the point on the ground

using a target, then the instrument displays the angle through which the theodolite has

to be turned and the distance by which the reflector should move.

Global Positioning System (GPS)

Global Positioning System (GPS) is developed by U.S. Defense department and is called

Navigational System with Time and Ranging Global Positioning System (NAVSTAR GPS)

or simply GPS.

For this purpose U.S. Air Force has stationed 24 satellites at an altitude of 20200 km above

the earth’s surface. The satellites have been positioned in such a way, at least four satellites

will be visible from any point on earth.



The user needs a GPS receiver to locate the position of any point on ground. The receive

processes the signals received from the satellite and compute the position (latitude and

longitude) and elevation of a point with reference to datum.



Automatic Level

An automatic level is a special leveling instrument used in surveying which contains an

optical compensator which maintains line of sight or line of collimation even though

instrument is slightly tilted.

E.g.: Wild NAK2 Automatic level

Soil Mechanics

Classification of Soil

Soil may be broadly classified as follows:

1. Classification based on grain size

2. Textural classification

3. AASHTO classification system

4. Unified soil classification system

(i) Grain Size Classification System for Soils

Grain size classification systems were based on grain size. In this system the terms clay, silt,

sand and gravel are used to indicate only particle size and not to signify nature of soil type.

There are several classification systems fin use, but commonly used systems are shown here.



(ii) Textural Classification of Soil

The classification of soil exclusively based on particle size and their percentage distribution

is known as textural classification system. This system specifically names the soil depending

on the percentage of sand, silt and clay. The triangular charts are used to classify soil by this

system.

Figure – 1 shows the typical textural classification system.

Fig-1: Textural Classification of U.S. Public Roads Administration

(iii) AASHTO classification system of Soil

AASHTO classification, (table-2) is otherwise known as PRA classification system. It was

originally developed in 1920 by the U.S. Bureau of Public Roads for the classification of soil

for highway subgrade use.

This system is developed based on particle size and plasticity characteristics of soil mass.

After some revision, this system was adopted by the AASHTO in 1945.



In this system the soils are divided into seven major groups. Some of the major groups further

divided into subgroups. A soil is classified by proceeding from left to right on the

classification chart to find first the group into which the soil test data will fill.

Soil having fine fractions are further classified based on their group index. The group index is

defined by the following equation.

Group index = (F – 35)[0.2 + 0.005 (LL – 40)] + 0.01(F – 15)(PI – 10)

F – Percentage passing 0.075mm size

LL – Liquid limit

PI – Plasticity index

When the group index value is higher, the quantity of the material is poorer.

Click Here to View AASHTO Classification Chart

(iv) Unified Soil Classification System

Unified soil classification system was originally developed by Casagrande (1948) and was

known as airfield classification system. It was adopted with some modification by the U.S.

Bureau of Reclamation and the U.S. Corps of Engineers.

This system is based on both grain size and plasticity characteristics of soil. The same system

with minor modification was adopted by ISI for general engineering purpose (IS 1498 –

1970).

IS system divides soil into three major groups, coarse grained, fine grained and organic soils

and other miscellaneous soil materials.

Coarse grained soils are those with more than 50% of the material larger than 0.075mm size.

Coarse grained soils are further classified into gravels (G) and sands (S). The gravels and

sands are further divided into four categories according to gradation, silt or clay content.

Fine grained soils are those for which more than 50% of soil finer than 0.075 mm sieve size.

They are divided into three sub-divisions as silt (M), clay (c), and organic salts and clays (O).

based on their plasticity nature they are added with L, M and H symbol to indicate low

plastic, medium plastic and high plastic respectively.

Examples:

GW – well graded gravel

GP – poorly graded gravel

GM – silty gravel

SW – well graded sand

SP – poorly graded sand

SM – silty sand

SC – clayey sand

CL – clay of low plastic

CI – clay of medium plastic

CH – clay of higher plastic

ML – silt of medium plastic

MI – silt of medium plastic

MH – silt of higher plastic

OL – organic silt and clays of low plastic

OI – organic silt and clays of medium plastic

OH – organic silt and clays of high plastic.

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Fine grained soils have been sub-divided into three subdivisions of low, medium and high

compressibility instead of two sub-divisions of the original Unified Soil Classification

System.

Table-3 below shows the classification system. Table 2 lists group symbols for soils of

table-3.

Table-2: Significance of letters for group symbol in table-3.

Soil Soil Component Symbol

Coarse Grained

Boulder None

Cobble None

Gravel G

Sand S

Fine Grained

Silt M

Clay C

Organic Matter O

Table – 3

Soil Soil Component Symbol

Peat Peat Pt

Applicable to Coarse grained Soils

Well graded W

Poorly Graded P

Applicable to Fine grained soils

Low compressibility

WL<35 L

Medium compressibility

(WL 35 to 50) I

High compressibility

(WL>50) H

The standard recommends that when a soil possesses characteristics of two groups either in

particle size distribution or in plasticity, it is designed by combination of group symbols.

Click Here to View Unified Soil Classification Chart

Field identification is recommended through the following tests:

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For fine grained soils

a) Visual examination

b) Dilatancy test

c) Toughness test

d) Dry strength test

e) Organic content and colour

f) Other identification test

Indian Standard Classification System for Soil

Indian Standard Classification System (ISC) was adopted by Bureau of Indian Standards is in

many respect similar to the Unified Soil Classification (USC) system.

Soils are divided into three broad divisions:

1. Coarse grained soils, when 50% or more of the total material by weight is retained on

75 micro IS sieve.

2. For fine grained soils, when more than 50% of the total material passes through 75

micron IS sieve.

3. If the soil is highly organic and contains a large percentage of organic matter and

particles of decomposed vegetation, it is kept in a separate category marked as peat

(Pt).

In all there are 18 groups of soils: 8 groups of coarse grained, 9 groups of fine grained and

one of peat.

Fig.2: Indian Standard Classification Plasticity Chart

Types of Foundation

Following are different types of foundations used in construction:

1. Shallow foundation

o Individual footing or isolated footing

o Combined footing

o Strip foundation

o Raft or mat foundation

2. Deep Foundation



o Pile foundation

o Drilled Shafts or caissons

Types of Shallow Foundations

1. Individual Footing or Isolated Footing

Individual footing or an isolated footing is the most common type of foundation used for

building construction. This foundation is constructed for single column and also called as pad

foundation.

The shape of individual footing is square or rectangle and is used when loads from structure

is carried by the columns. Size is calculated based on the load on the column and safe bearing

capacity of soil.

Rectangular isolated footing is selected when the foundation experiences moments due to

eccentricity of loads or due to horizontal forces.

For example, Consider a column with vertical load of 200 kN and safe bearing capacity of

100 kN/m2 then the area of the footing required will be 200/100 = 2m2. So, for a square

footing, length and width of footing will be 1.414 m x 1.414 m.

2. Combined Footing

Combined footing is constructed when two or more columns are close enough and their

isolated footings overlap each other. It is a combination of isolated footings, but their

structural design differs.

The shape of this footing is rectangle and is used when loads from structure is carried by the

columns.

3. Spread footings or Strip footings and Wall footings

Spread footings are those whose base is more wider than a typical load bearing wall

foundations. The wider base of this footing type spreads the weight from the building

structure over more area and provides better stability.

Fig: Spread Footing

Spread footings and wall footings are used for individual columns, walls and bridge piers

where the bearing soil layer is within 3m (10 feet) from the ground surface. Soil bearing

capacity must be sufficient to support the weight of the structure over the base area of the

structure.

These should not be used on soils where there is any possibility of ground flow of water

above bearing layer of soil which may result in scour or liquefaction.

4. Raft or Mat Foundations

Raft or mat foundations are the types of foundation which are spread across the entire area of

the building to support heavy structural loads from columns and walls.



The use of mat foundation is for columns and walls foundations where the loads from

structure on columns and walls are very high. This is used to prevent differential settlement

of individual footings, thus designed as a single mat (or combined footing) of all the load

bearing elements of the structure.

It is suitable for expansive soils whose bearing capacity is less for suitability of spread

footings and wall footings. Raft foundation is economical when one-half area of the structure

is covered with individual footings and wall footings are provided.

These foundations should not be used where the groundwater table is above the bearing

surface of the soil. Use of foundation in such conditions may lead to scour and liquefaction.

Types of Deep Foundation

5. Pile Foundations

Pile foundation is a type of deep foundation which is used to transfer heavy loads from the

structure to a hard rock strata much deep below the ground level.

Fig: Pile Foundation



Pile foundations are used to transfer heavy loads of structures through columns to hard soil

strata which is much below ground level where shallow foundations such as spread footings

and mat footings cannot be used. This is also used to prevent uplift of structure due to lateral

loads such as earthquake and wind forces.

Pile foundations are generally used for soils where soil conditions near the ground surface is

not suitable for heavy loads. The depth of hard rock strata may be 5m to 50m (15 feet to 150

feet) deep from the ground surface.

Pile foundation resists the loads from structure by skin friction and by end bearing. Use of

pile foundations also prevents differential settlement of foundations.

6. Drilled Shafts or Caisson Foundation

Drilled shafts, also called as caissons, is a type of deep foundation and has action similar to

pile foundations discussed above, but are high capacity cast-in-situ foundations. It resists

loads from structure through shaft resistance, toe resistance and / or combination of both of

these. The construction of drilled shafts or caissons are done using an auger.

Fig: Drilled Shafts or Caisson Foundation (Source: Hayward Baker)

Drilled shafts can transfer column loads larger than pile foundations. It is used where depth of

hard strata below ground level is location within 10m to 100m (25 feet to 300 feet).

Drilled shafts or caisson foundation is not suitable when deep deposits of soft clays and loose,

water-bearing granular soils exists. It is also not suitable for soils where caving formations

are difficult to stabilize, soils made up of boulders, artesian aquifer exists.

Irrigation

Irrigation is defined as the science of artificially providing water to the land in accordance

with the “crop requirement” throughout the “crop period” for the complete nourishment of

the plant.

Types of Irrigation

Irrigation can be broadly divided into two main types, namely:

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1. Surface Irrigation

2. Sub-surface Irrigation

1. Surface Irrigation

Surface irrigation is again divided into Flow Irrigation and Lift irrigation.

Flow Irrigation

In this type of irrigation, the water available at higher levels is allowed to move to the crops

present in the lower level by the action of gravity. Flow irrigation is again classified into:

1. Perennial Irrigation

2. Flood Irrigation

1. Perennial Irrigation

This irrigation system guarantees continuous and constant water supply to the crops

throughout the crop period as per the requirement of the crop. This system supply water to

the crops through a canal distribution system that takes off from a weir or a reservoir.

If the irrigation water is taken by diverting the river runoff to the main canal by the

construction of a diversion weir, then this irrigation is called as direct irrigation. If a dam is

constructed across the river and the stored water is used to perform irrigation, then it is called

storage irrigation.

Direct irrigation is the simplest and most economical perennial irrigation. The perennial

irrigation is also called as Controlled Irrigation.

2. Flood Irrigation

Flood irrigation also called inundation irrigation is an irrigation method that intentionally

creates a flooded land condition. This makes the soil completely saturated. After this,

occasional natural rainfall is sufficient for the maturity of the crops.

Flood Irrigation

This irrigation method is best suitable for lands where there is a river nearby with a higher

water level and a controlled flow of water to the land is not possible. So, the water is allowed



to flow in surplus until a flooded condition is reached. Hence this irrigation is an uncontrolled

irrigation system.

Lift Irrigation

In this type of irrigation, the water is lifted with the help of a mechanical or manual

arrangement like pumps, etc. Using the water from wells and tube wells to water the crops at

higher levels are examples of lift irrigation.

2. Sub-Surface Irrigation System

In the case of the sub-surface irrigation system, the soil surface is not made wet. Instead, the

water sufficient for the crops is provided by means of underground water by the action of

capillarity.

Sub-Surface Irrigation System

Sub-surface irrigation can be performed either naturally or artificially.

Natural Sub-Surface Irrigation

There are possibilities of water leakage from the water channels or pipes. The water moves

through the subsoil and may irrigate the crops nearby. This water leakage may also increase

the water level of underground water which also helps to nourish the crops.

This way, when underground irrigation is achieved without any additional effort, it is defined

as natural sub-surface irrigation.

Artificial Sub-Surface Irrigation System

In the artificial sub-irrigation system, artificial water channels are provided in the

underground and water is supplied to the crops under the action of capillarity. This irrigation

type is very costly and employed for crops that provide high returns and profit.

In certain areas, small ditches are made in different locations of the irrigation land, so that

water from the ditches may percolate and nourish the crops, which also is a method of sub-

surface irrigation system.



Hydraulic structure- A hydraulic structure is a structure submerged or partially submerged

in any body of water, which disrupts the natural flow of water. They can be used to divert,

disrupt or completely stop the flow. An example of a hydraulic structure would be a dam,

which slows the normal flow rate of river in order to power turbines.

Canals

Canals are waterways channels, or artificial waterways, for water conveyance, or to service

water transport vehicles. They may also help with irrigation. It can be thought of as an

artificial version of a river.

Siphon

A siphon is any of a wide variety of devices that involve the flow of liquids through tubes. In

a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which

causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered

by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at

a level lower than the surface of the reservoir from which it came.

Weir

A weir or low head dam is a barrier across the width of a river that alters the flow

characteristics of water and usually results in a change in the height of the river level. There

are many designs of weir, but commonly water flows freely over the top of the weir crest

before cascading down to a lower level.

Dam

A dam is a barrier that stops or restricts the flow of water or underground streams. Reservoirs

created by dams not only suppress floods but also provide water for activities such as

irrigation, human consumption, industrial use, aquaculture, and navigability.

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