Unit 1

Building, Planning, and Construction

Q.1 What are the Branches in civil engineering?

Sol:

Civil engineering is the design, implementation, and maintenance of public works. This involves facilities and structures such as arenas, large scale monuments, government buildings, transportation routes as well as other structures. Engineers will either work for the city or for a private firm that has been hired by the city. Some civil engineers work in the private sector on projects for independent companies. There are several types of civil engineering. A civil engineer can specialize in a number of different civil engineering branches. Those branches are described briefly below:

• Structural Engineering
• Geotechnical Engineering
• Environmental Engineering
• Transportation Engineering
• Water Resource Engineering
• Earthquake Engineering
• Material Engineering
• Construction Engineering
• Surveying
• Municipal Engineering
• Coastal Engineering
• Tunnel Engineering

Scope of Civil Engineering Civil engineering is the oldest branch of engineering which is growing right from the stone age of civilization. American society of civil engineering defines civil engineering as the profession in which a knowledge of the mathematical, and physical sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize economically the materials and forces of nature for the progressive well being of man.

Q.2 What are the Roles of Civil Engineers in various construction activities?

Sol:

A civil engineer has to conceive, plan, estimate, get approval, create, and maintain all civil engineering activities.

A civil engineer has a very important role in the development of the following infrastructure:

• Measure, and map the earth’s surface.
• Plan new townships  and extension of existing towns
• Build suitable structures for the rural, and urban areas for various utilities
• Build tanks and dams to exploit water resources.
• Build river navigation and flood control projects.
• Provide, and maintain communication systems like roads, railways, harbours and airports
• Purify, and supply water to the needy areas like houses, schools, offices, etc.
• Build canals and distributaries to take water to agricultural fields
• Devise systems for control, and efficient flow of traffic
• Provide, and maintain a solid, and wastewater disposal system
• Monitor land, water, and air pollution, and take measures to control them

Fast-growing industrialization has put heavy responsibilities on civil engineers to preserve, and protect the environment.

Q.3 Explain the Selection of site, and its factors affecting selection of site?

Sol:

Site selection indicates the practice of new facility location, both for business and government. Site selection involves measuring the needs of a new project against the merits of potential locations. The practice came of age during the 20th century, as governments and corporate operations expanded to new geographies on a national, and international scale

Factors affecting the selection of site

The site for a residential building should present a peaceful environment, good landscape, sun for the most part of the day, and uninterrupted flow of natural air. The following factors need to be studied in-depth while selecting the site for a residential building:

• Topography
• Nature of sub-soil
• Position of the groundwater table
• Facilities
• Neighbourhood
• Undesirable things near the site
• Vegetation
• The shape of the site
• Availability of men, and materials
• Proximity to sea-shore, river or lake or the place of natural beauty

Q.4 Define  F.S.I., Carpet area, Plinth area?

Sol:

F.S.I.,

FSI stands for Floor Space Index also known as Floor Area Ratio (FAR). FSI means the ratio between the area of a covered floor (Built-up Area) to the area of that plot (l, and) on which a building stands.

It is calculated by dividing the total covered built-up area on all floors of a building by the area of the plot it stands on. For instance, if you have 1,000 square feet of l, and on which you want to build a residential or commercial building, and the FSI in your locality is 1.5, then you could build up to 1,500 sq.

Carpet area

The carpet area is the area that can be used to spread a carpet inside the house. It is the net usable area of the apartment. It includes the thickness of the internal wall but excludes the balcony or terrace. Technically, the distance between the inner walls is a carpet area.

Plinth area

The plinth area is the covered built-up area measured at the floor level of any storey or the floor level of the basement. The plinth area is also called a built-up area and is the entire area occupied by the building including internal, and external walls. The plinth area is generally 10-20% more than the carpet area.

Q.5 Explain briefly the cost of the building?

Sol:

Cost reduction through adhoc methods

Foundation

• Normally the foundation cost comes to about 10 to 15% of the total building, and usually foundation depth of 3 to 4 ft. Is adopted for a single or double store building, and also the concrete bed of (15 Cms.) is used for the foundation which could be avoided.

• It is recommended to adopt a foundation depth of 2 ft. (0.6m) for normal soil like gravely soil, red soils, etc., and use the un-coursed rubble masonry with the bond stones and good packing. Similarly, the foundation width is rationalized to 2 ft. (0.6m). To avoid cracks formation in the foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.

• It is further suggested adopt an arch foundation in ordinary soil for effecting a reduction in construction cost up to 40%. This kind of foundation will help in bridging the loose pockets of soil that occurs along the foundation.

• In the case of black cotton, and other soft soils it is recommended to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.

Plinth

• It is suggested to adopt 1 ft. Height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided, and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%. It is necessary to take the precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface, and crack formation.

Walling

• Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building, and 41/2 ” for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls

Rat – trap bond wall

• It is a cavity wall construction with the added advantage of thermal comfort, and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce the material cost of bricks by 25%, and about 10to 15% in the masonry cost. By adopting a rat-trap bond method one can create an aesthetically pleasing wall surface, and plastering can be avoided.

Concrete block walling

• In view of high energy consumption by burnt brick it is suggested to use a concrete block (block hollow, and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of the wall resulting in a higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.

Soil cement block technology

• It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy-efficient method of construction where the soil is mixed with 5%, and above the cement, and pressed in h, and operated machine, and cured well, and then used in the masonry. This masonry doesn’t require plastering on both sides of the wall. The overall economy that could be achieved with the soil-cement technology is about 15 to 20% compared to the conventional method of construction.

Doors and windows

• It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%. Similarly for shutters commercially available block boards, fiber or wooden practical boards, etc., shall be used for reducing the cost by about 25%. By adopting brick jelly work, and precast components effective ventilation could be provided to the building, and also the construction cost could be saved up to 50% over the window components.

Lintals and Chajjas

• The traditional R.C.C. Lintels which are costly can be replaced by brick arches for small spans and save construction costs up to 30 to 40% over the traditional method of construction. By adopting arches of different shapes a good architectural pleasing appearance can be given to the external wall surfaces of the brick masonry.

Roofing

• Normally(12.5 cms) thick R.C.C. Slabs are used for roofing of residential buildings. By adopting rationally designed in situ construction practices like filler slabs and precast elements the construction cost of roofing can be reduced by about 20 to 25%.

Filler slabs

• They are normal RCC slabs where bottom half (tension) concrete portions are replaced by filler materials such as bricks, tiles, cellular concrete blocks, etc. These filler materials are so placed as not to compromise structural strength, result in replacing unwanted, and non-functional tension concrete, thus resulting in economy. These are safe, sound, and provide aesthetically pleasing pattern ceilings and also need no plaster.

Finishing Work

• The cost of finishing items like sanitary, electricity, painting, etc., varies depending upon the type, and quality of products used in the building, and its cost reduction is left to the individual choice and liking.

Prevention of slum

• The formation of the slum is a very slow process and extreme care should be exercised by the authority to prevent the springing up of new slums in the town.
• Some of the important measures which can be taken to effectively prevent slum formation.

 Cheap Housing

• Sufficient no of cheap housing should be made available to the poor people.

Compulsion To Employers

• The employer of a good number of labourers may be compelled or forced to provide housing accommodation for their staff.

Construction of Buildings

• Certain rules and regulations may be framed, and strictly enforced to restrict the coming up of buildings of subnormal standards

Maintenance, and Repair

• The responsibility of maintenance, and carrying out repair should be fixed and defined in housing codes or acts. It then becomes the duty of the landlord or tenant to keep an existing building in a good condition.

Social Education

• It is possible to check the growth of slums by carrying out effective social education of the slum dwellers, the social education makes the slum dweller conscious of the evils of the slum, and a great improvement in the living standard of slum dwellers could be achieved

Unauthorized Construction

• It is absolutely necessary to arrest immediately the unauthorized construction in the form of huts and temporary structures on a vacant piece of l, and.
• The authorities concerned should take drastic action in demolishing and removing such unauthorized construction.

Q.6 Briefly explain the Classification, properties and uses of materials - bricks, stones, sand, aggregates, cement, concrete, steel?

Sol:

BRICKS

Constituents of good brick earth: Bricks are the most commonly used construction material. Bricks are prepared by moulding clay in rectangular blocks of uniform size and then drying, and burning these blocks. In order to get a good quality brick, the brick earth should contain the following constituents.

• Silica
• Alumina
• Lime
• Iron oxide
• Magnesia

Brick plays a very important role in the field of civil engineering construction. Bricks are used as an alternative of stones in construction purposes.

• USES OF CEMENT

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) use as an aggregate in concrete
6. Manufacture of surki (powdered bricks) to be used in lime plaster, and lime concrete

Classification of Bricks as per constituent materials

There are various types of bricks used in masonry

• Common Burnt Clay Bricks
• Sand Lime Bricks (Calcium Silicate Bricks)
• Engineering Bricks
• Concrete Bricks
• Fly ash Clay Bricks

Common Burnt Clay Bricks

Common burnt clay bricks are formed by pressing in moulds. Then these bricks are dried and fired in a kiln. Common burnt clay bricks are used in general work with no special attractive appearances. When these bricks are used in walls, they require plastering or rendering.

Sand Lime Bricks

 Sand lime bricks are made by mixing sand, fly ash, and lime followed by a chemical process during wet mixing. The mix is then moulded under pressure forming the brick. These bricks can offer advantages over clay bricks such as their colour appearance is grey instead of the regular reddish colour. Their shape is uniform and presents a smoother finish that doesn’t require plastering. These bricks offer excellent strength as a load-bearing member.

Engineering Bricks

Engineering bricks are bricks manufactured at extremely high temperatures, forming a dense, and strong brick, allowing the brick to limit strength, and water absorption. Engineering bricks offer excellent load-bearing capacity damp-proof characteristics and chemical resisting properties. Concrete Bricks Concrete bricks are made from solid concrete. Concrete bricks are usually placed in facades, fences and provide an excellent aesthetic presence. These bricks can be manufactured to provide different colours as pigmented during its production.

Fly Ash Clay Bricks

Fly ash clay bricks are manufactured with clay, and fly ash, at about 1,000 degrees C. Some studies have shown that these bricks tend to fail poor produce pop-outs when bricks come into contact with moisture, and water, causing the bricks to expand.

• ENGINEERING PROPERTIES OF CEMENT

To know the quality of bricks following 7 tests can be performed. In these tests, some are performed in a laboratory, and the rest are on the field.

• Compressive strength test
• Water Absorption test
• Efflorescence test
• Hardness test
• Size, Shape, and Colour test
• Soundness test

Structure test Compressive strength test

This test is done to know the compressive strength of brick. It is also called the crushing strength of brick. Generally, 5 specimens of bricks are taken to the laboratory for testing and tested one by one. In this test, a brick specimen is put on a crushing machine and applied pressure till it breaks. The ultimate pressure at which brick is crushed is taken into account. All five brick specimens are tested one by one, and the average result is taken as the brick’s compressive/crushing strength.

Water Absorption test In this test bricks are weighed in dry condition, and let immersed in freshwater for 24 hours. After 24 hours of immersion, those are taken out from the water and wipe out with a cloth. Then brick is weighed in wet condition. The difference between weights is the water absorbed by brick. The percentage of water absorption is then calculated. The less water absorbed by brick the greater it's quality. Good quality brick doesn’t absorb more than 20% water of its own weight.

Efflorescence test The presence of alkalies in bricks is harmful, and they form a grey or white layer on the brick surface by absorbing moisture. To find out the presence of alkalis in bricks this test is performed. In this test, a brick is immersed in freshwater for 24 hours and then it’s taken out from the water, and allowed to dry in shade. If the whitish layer is not visible on the surface it proofs the absence of alkalis in brick. If the whitish layer visible about 10% of the brick surface then the presence of alkalis is inacceptable range. If that is about 50% of the surface then it is moderate. If the alkalies’ presence is over 50% then the brick is severely affected by alkalies.

Hardness test

In this test, a scratch is made on a brick surface with a hard thing. If that doesn’t leave any impression on brick then that is good quality brick.

Size, shape, and colour test

In this test randomly collected 20 bricks are staked along lengthwise, width-wise, and height-wise, and then those are measured to know the variation of sizes as per standard. Bricks are closely viewed to check if its edges are sharp, and straight, and uniform in shape. A good quality brick should have bright, and uniform colour throughout.

Soundness test

In this test, two bricks are held by both hands and struck with one another. If the bricks give a clear metallic ringing sound and don’t break then those are good quality bricks.

Structure test In this test a brick is broken or a broken brick is collected, and closely observed. If there are any flaws, cracks, or holes present on that broken face then that isn’t good quality brick.

STONES

• USES OF STONES

1. Stone masonry is used for the construction of foundations, walls, columns and arches.
2. Stones are used for flooring.
3. Stone slabs are used as damp proof courses, lintels and even as roofing materials.
4. Stones with good appearance are used for the face works of buildings. Polished marbles and granite are commonly used for face works.
5. Stones are used for paving roads, footpaths and open spaces around the buildings.
6. Stones are also used in the constructions of piers and abutments of bridges, dams and retaining walls.
7. Crushed stones with graved are used to provide a base course for roads. When mixed with tar they form a finishing coat.

Crushed stones are used in the following works also:

1. As a basic inert material in concrete.
2. For making artificial stones and building blocks.
3. As railway ballast.

• ENGINEERING PROPERTIES OF STONES

1. STRUCTURE

The structure of the stone may be stratified (layered) or unstratified. Structured stones should be easily dressed, and suitable for the superstructure. Unstratified stones are hard and difficult to dress. They are preferred for the foundation works.

2. TEXTURE

Fine-grained stones with homogeneous distribution look attractive, and hence they are used for carving. Such stones are usually strong, and durable.

3. DENSITY

Denser stones are stronger. Lightweight stones are weak. Hence stones with a specific gravity less than 2.4 are considered unsuitable for buildings.

4. APPEARANCE

A stone with uniform and attractive colour is durable if grains are compact. Marble and granite get a very good appearance, when polished. Hence they are used for face works in buildings.

5. STRENGTH

Strength is an important property to be looked into before selecting stone as a building block. Indian standard code recommends, minimum crushing strength of 3.5 N/mm2 for any building block

6. HARDNESS

It is an important property to be considered when the stone is used for flooring and pavement. The coefficient of hardness is to be found by conducting a test on the standard specimen in Dory’s testing machine. For road works coefficient of hardness should be at least 17. For building works stones with a coefficient of hardness less than 14 should not be used.

7. PERCENTAGE WEAR

It is measured by an attrition test. It is an important property to be considered in selecting aggregate for road works and railway ballast. A good stone should not show the wear of more than 2%.

8. POROSITY, AND ABSORPTION

All stones have pores and hence absorb water. The reaction of water with stone causes disintegration. The absorption test is specified as the percentage of water absorbed by the stone when it is immersed underwater for 24 hours. For a good stone, it should be as small as possible and in no case more than 5.

9. WEATHERING

Rain, and wind cause loss of good appearance of stones. Hence stones with good weather resistance should be used for face works.

10. TOUGHNESS

The resistance to impact is called toughness. It is determined by the impact test. Stones with a toughness index of more than 19 are preferred for road works. Toughness index 13 to 19 is considered as medium tough, and stones with toughness index less than 13 are poor stones.

11. RESISTANCE TO FIRE

Sandstones resist fire better. Argillaceous materials, though poor in strength, are good in resisting fire.

12. EASE IN DRESSING

The cost of dressing contributes to the cost of stone masonry to a great extent. The dressing is easy in stones with lesser strength. Hence an engineer should look into sufficient strength rather than high strength while selecting stones for building works.

13. SEASONING

The stones obtained from the quarry contain moisture in the pores. The strength of the stone improves if this moisture is removed before using the stone. The process of removing moisture from pores is called seasoning. The best way of seasoning is to allow it to the action of nature for 6 to 12 months. This is very much required in the case of laterite stones.

SAND

Sand is a mixture of small grains of rock, and granular materials which are mainly defined by size, being finer than gravel, and coarser than silt., and ranging in size from 0.06 mm to 2 mm. Particles that are larger than 0.0078125 mm but smaller than 0.0625 mm are termed silt.

Sand is made by erosion or broken pebbles and weathering of rocks, which is carried by seas or rivers., and freezing, and thawing during the winter break rock up the sand will be made. Sometimes Sand on beaches can also be made by small broken-up pieces of coral, bone, and shell, which are broken up by predators and then battered by the sea, and even tiny pieces of glass from bottles discarded in the sea, and other mineral materials or the bones of fishes or other oceanic animals. Sand can be also considered as a textural class of soil or soil type.

In the real world, there are a lot of situations where we can find uses for sand. The followings are the common sand uses.

1. We can use sand to filter water; it works like an abrasive.
2. We can use sand to give a grip to our painting or wall art by combining 2 cups of paint with a ¾ cup of sand.
3. People make sandpaper by gluing sand to a paper.
4. While bunging metal, we can mix sand with clay binder for frameworks used in the foundries.
5. Sand can be used for cleaning up oil leaks or any spill by dredging sand on that spill. The material will form clumps by soaking up, and we can quickly clean the mess.
6. Sand can be used as a road base which is a protective layer underneath all roads
7. Industrial sand is used to make glass, as foundry sand, and as abrasive sand.
8. One creative usage of sand is serving as a candle holder. We can try putting some sand before pouring tea light or any candle in a glass. It holds the candle still, and refrain the candle from rolling by giving it an excellent decoration.
9. Adds texture, and aesthetic appeal to space.
10. Sand is most pure to handle, promptly available, and economically wise.
11. We can make children’s sandpit to keep the play areas safer. It is quite inexpensive as well.
12. We use sand in aquariums, fabricating artificial fringing reefs, and in human-made beaches
13. Sandy soils are ideal for growing crops, fruits and vegetables like watermelon, peaches, peanuts, etc.
14. Sand can light a path by filling mason jars with sand, and tea light which is another inexpensive way to make a walkway glow.
15. Sand can be used for cleaning narrow neck receptacle by putting a little sand, and warm soapy water in the container.
16. We can keep an item steady which needs repairing by using sand. Burying the broken pieces under sand grains helps to hold the elements together while gluing.
17. Sand helps to improve resistance (and thus traffic safety) in icy or snowy conditions.
18. We need sand in the beaches where tides, storms, or any form of preconceived changes to the shoreline crumble the first sand.
19. Sand containing silica is used for making glass in the automobile, and food industry- even household products for the kitchen.
20. Sand is strong str, and which is used for plaster, mortar, concrete, and asphalt.
21. The usual bricks formulated of clay only is way weaker, and lesser in weight than blocks made of clay mixed with sand

Followings are the desirable properties of sand: 

• Should be completely inert. (i.e., should not have any chemical activity).
• Grains should be sharp, strong & angular.
• Should not contain any hygroscopic salts (i.e., CaCl2, MgCl2, etc.).
• Should not contain clay & silt; usually, 3-4% clay & silt is ordinarily permitted for practical reasons.
• There should be no organic matter.

AGGREGATES

Aggregate is an aggregation of non-metallic minerals obtained in particulate form, and can be processed, and used for civil, and highway engineering construction.

Aggregates are mainly classified into two categories:

1. Fine Aggregate
2. Coarse Aggregate

Aggregates are used in concrete to provide economy in the cost of concrete. Aggregates act as filler only. These do not react with cement and water. But there are properties or characteristics of aggregate which influence the properties of the resulting concrete mix. These are as follows.

1. Composition
2. Size & Shape
3. Surface Texture
4. Specific Gravity
5. Bulk Density
6. Voids
7. Porosity & Absorption
8. Bulking of Sand
9. Fineness Modulus of Aggregate
10. Surface Index of Aggregate
11. Deleterious Material
12. Crushing Value of Aggregate
13. Impact Value of Aggregate
14. Abrasion Value of Aggregate

1. COMPOSITION

Aggregates consisting of materials that can react with alkalies in cement, and cause excessive expansion, cracking, and deterioration of concrete mix should never be used. Therefore, it is required to test aggregates to know whether there is a presence of any such constituents in aggregate or not.

2. SIZE & SHAPE

The size and shape of the aggregate particles greatly influence the quantity of cement required in the concrete mix, and hence ultimately the economy of concrete. For the preparation of an economical concrete mix, one should use the largest coarse aggregates feasible for the structure. IS-456 suggests the following recommendation to decide the maximum size of coarse aggregate to be used in the P.C.C & R.C.C mix.

The maximum size of aggregate should be less than

• One-fourth of the minimum dimension of the concrete member.
• One-fifth of the minimum dimension of the reinforced concrete member.
• The minimum clear spacing between reinforced bars or 5 mm less than the minimum cover between the reinforced bars and form, whichever is smaller for heavily reinforced concrete members such as the ribs of the main bars.

3. SURFACE TEXTURE

The development of hard bond strength between aggregate particles and cement paste depends upon the surface texture, surface roughness, and surface porosity of the aggregate particles. If the surface is rough but porous, maximum bond strength develops. In porous surface aggregates, the bond strength increases due to the setting of cement paste in the pores.

4. SPECIFIC GRAVITY

The ratio of the weight of oven-dried aggregates maintained for 24 hours at a temperature of 100 to 1100C, to the weight of an equal volume of water displaced by saturated dry surface aggregate is known as the specific gravity of aggregates.

5. BULK DENSITY

It is defined as the weight of the aggregate required to fill a container of unit volume. It is generally expressed in kg/liter.

Bulk density of aggregates depends upon the following 3 factors.

• Degree of compaction
• Grading of aggregates
• The shape of aggregate particles

6. VOIDS

The empty spaces between the aggregate particles are known as voids. The volume of void equals the difference between the gross volume of the aggregate mass and the volume occupied by the particles alone.

7. POROSITY & ABSORPTION

The minute holes formed in rocks during solidification of the molten magma, due to air bubbles, are known as pores. Rocks containing pores are called porous rocks. Water absorption may be defined as the difference between the weight of very dry aggregates and the weight of the saturated aggregates with surface dry conditions.

Depending upon the amount of moisture content in aggregates, it can exist in any of the 4 conditions.

• Very dry aggregate ( having no moisture)
• Dry aggregate (contain some moisture in its pores)
• Saturated surface dry aggregate (pores filled with moisture but no moisture on the surface)
• Moist or wet aggregates (pores are filled with moisture, and also having moisture on the surface)

8. BULKING OF SAND

It can be defined as an increase in the bulk volume of the quantity of sand (i.e. fine aggregate) in a moist condition over the volume of the same quantity of dry or completely saturated sand. The ratio of the volume of moist sand due to the volume of sand when dry is called the bulking factor.

9. FINENESS MODULUS

Fineness modulus is an empirical factor obtained by adding the cumulative percentages of aggregate retained on each of the standard sieves ranging from 80 mm to 150 microns and dividing this sum by 100.

Fineness modulus is generally used to get an idea of how coarse or fine the aggregate is. More fineness modulus value indicates that the aggregate is coarser, and a small value of fineness modulus indicates that the aggregate is finer.

10. SPECIFIC SURFACE OF AGGREGATE

The surface area per unit weight of the material is termed as a specific surface. This is an indirect measure of the aggregate grading. Specific surface increases with the reduction in the size of the aggregate particle. The specific surface area of the fine aggregate is very much more than that of coarse aggregate.

11. DELETERIOUS MATERIALS

Aggregates should not contain any harmful material in such a quantity so as to affect the strength, and durability of the concrete. Such harmful materials are called deleterious materials. Deleterious materials may cause one of the following effects

• To interfere with the hydration of cement
• To prevent the development of proper bond
• To reduce strength and durability
• To modify setting times

12. CRUSHING VALUE

The aggregates crushing value gives a relative measure of the resistance of an aggregate to crushing under gradually applied compressive load. The aggregate crushing strength value is a useful factor to know the behavior of aggregates when subjected to compressive loads.

13. IMPACT VALUE

The aggregate impact value gives a relative measure of the resistance of an aggregate to sudden shock or impact. The impact value of an aggregate is sometimes used as an alternative to its crushing value.

14. ABRASION VALUE OF AGGREGATES

The abrasion value gives a relative measure of the resistance of an aggregate to wear when it is rotated in a cylinder along with some abrasive charge.

CEMENT

Cement is a binder, a substance that sets and hardens and can bind other materials together. Cement used in construction can be characterized as being either hydraulic or non-hydraulic, depending upon the ability of the cement to be used in the presence of water. Non-hydraulic cement will not set-in wet conditions or underwater, rather it sets as it dries and reacts with carbon dioxide in the air. It can be attacked by some aggressive chemicals after setting. Hydraulic cement is made by replacing some of the cement in a mix with activated aluminium silicates, pozzolanas, such as fly ash. The chemical reaction results in hydrates that are not very water-soluble, and so are quite durable in water and safe from chemical attack. This allows setting in wet condition or underwater, and further protects the hardened material from chemical attack (e.g., Portland cement).

• USE OF CEMENT

• Cement mortar for Masonry work, plaster, and pointing, etc.
• Concrete for laying floors, roofs, and constructing lintels, beams, weather shed, stairs, pillars, etc.
• Construction for important engineering structures such as bridges, culverts, dams, tunnels, lighthouses, clocks, etc.
• Construction of water, wells, tennis courts, septic tanks, lamp posts, telephone cabins, etc.
• Making joints for joints, pipes, etc.
• Manufacturing of precast pipes, garden seats, artistically designed wens, flower posts, etc.
• Preparation of foundation, watertight floors, footpaths, etc.

• ENGINEERING PROPERTIES OF CEMENT

Fineness

• This test is carried out to check the proper grinding of cement. The fineness of cement particles may be determined either by a sieve test or permeability apparatus test.
• In the sieve test, the cement weighing 100 gm is taken, and it is continuously passed for 15 minutes through standard BIS sieve no. 9. The residue is then weighed, and this weight should not be more than 10% of the original weight.
• In the permeability apparatus test, a specific area of cement particles is calculated. This test is better than a sieve test. The specific surface acts as a measure of the frequency of particles of average size.

Compressive strength

• This test is carried out to determine the compressive strength of cement.
• The mortar of cement and sand is prepared in the ratio of 1:3.
• Water is added to mortar in a water cement ratio of 0.4.
• The mortar is placed in moulds. The test specimens are in the form of cubes and the moulds are of metals. For 70.6 mm, and 76 mm cubes, the cement required is 185gm, and 235 gm respectively.
• Then the mortar is compacted in a vibrating machine for 2 minutes and the moulds are placed in a damp cabin for 24 hours.
• The specimens are removed from the moulds and they are submerged in clean water for curing.
• The cubes are then tested in a compression testing machine at the end of 3daysand 7 days. Thus compressive strength was found out.

Consistency

• The purpose of this test is to determine the percentage of water required for preparing cement pastes for other tests.
• Take 300 gm of cement, and add 30 percent by weight or 90 gm of water to it.
• Mix water, and cement thoroughly.
• Fill the mould of the Vicat apparatus and the gauging time should be 3.75 to 4.25 minutes.
• Vicat apparatus consists of a needle is attached to a movable rod with an indicator attached to it.
• There are three attachments: square needle, plunger, and needle with an annular collar.
• The plunger is attached to the movable rod. The plunger is gently lowered on the paste in the mould.
• The settlement of the plunger is noted. If the penetration is between 5 mm to 7 mm from the bottom of the mould, the water added is correct. If not the process is repeated with different percentages of water till the desired penetration is obtained.

Setting time

• This test is used to detect the deterioration of cement due to storage. The test is performed to find out the initial setting time, and final setting time.
• Cement mixed with water and cement paste is filled in the Vicat mould.
• The square needle is attached to the moving rod of the Vicat apparatus.
• The needle is quickly released, and it is allowed to penetrate the cement paste. In the beginning, the needle penetrates completely. The procedure is repeated at regular intervals till the needle does not penetrate completely. (up to 5mm from bottom)
• Initial setting time equal to or less than 30min for ordinary Portland cement, and 60 min for low heat cement.
• The cement paste is prepared as above, and it is filled in the Vicat mould.
• The needle with an annular collar is attached to the moving rod of the Vicat apparatus.
• The needle is gently released. The time at which the needle makes an impression on the test block and the collar fails to do so is noted.
• The final setting time is the difference between the time at which water was added to cement and time as recorded in the previous step, and it is equal to or less than 10hours.

Soundness

• The purpose of this test is to detect the presence of uncombined lime in the cement.
• The cement paste is prepared.
• The mould is placed, and it is filled with cement paste.
• It is covered at the top by another glass plate. A small weight is placed at the top, and the whole assembly is submerged in water for 24 hours.
• The distance between the points of the indicator is noted. The mould is again placed in water, and heat is applied in such a way that the boiling point of water is reached in about 30 minutes. The boiling of water is continued for one hour.
• The mould is removed from the water, and it is allowed to cool down.
• The distance between the points of the indicator is again measured. The difference between the two readings indicates the expansion of cement, and it should not exceed 10 mm.

Tensile strength

• This test was formerly used to have an indirect indication of the compressive strength of cement.
• The mortar of sand and cement is prepared.
• The water is added to the mortar.
• The mortar is placed in briquette moulds. The mould is filled with mortar, and then a small heap of mortar is formed at its top. It is beaten down by a standard spatula till water appears on the surface. The same procedure is repeated for the other face of the briquette.
• The briquettes are kept in a damp for 24 hours and carefully removed from the moulds.
• The briquettes are tested in a testing machine at the end of 3, and 7 days and the average is found out

CONCRETE

Concrete is a composite material composed mainly of water, aggregate, and cement. Often, additives and reinforcements are included in the mixture to achieve the desired physical properties of the finished material. When these ingredients are mixed together, they form a fluid mass that is easily moulded into shape. Over time, the cement forms a hard matrix that binds the rest of the ingredients together into a durable stone-like material with many uses.

• USES OF CONCRETE

1. It’s an important building product. Concrete is chosen over wood as a construction material.
2. It is a durable, and cost-effective material that is a necessity for underground use. 
3. Concrete is a sustainable choice for residential, and commercial projects. 
4. The strength of concrete increases over time. 
5. Concrete can hold up against weather conditions and is easy to maintain. 
6. It is budget-friendly to use everywhere. It is easy to repair & energy efficient.
7. Concrete is safe for building occupants.
8. Concrete is an inert material that doesn’t burn, mildew, or feed rot.
9. Its superior structural integrity provides an added degree of protection from severe weather as well as an earthquake.
10. Concrete walls and floors make a home a quiet place of rest, relaxation, and rejuvenation.
11. Concrete is produced from locally available materials and leaves a small environmental footprint while still providing high-level durability.
12. It is used as an aggregate in roadbeds or as granular materials while making new concrete. 
13. The concrete is fire resistant. It can resist the extreme level of flames and heat which is a good choice of the ceiling in a storage room. 
14. Concrete can be shaped in various forms when freshly mixed. 
15. Concrete isn’t sensitive to moisture.
16. It doesn’t release any volatile organic compounds into the environment-friendly air. 
17. Concrete gives a longer service life. 
18. It keeps the home safe from insects. It doesn’t attract insect pests and rodents. That’s why small animals cannot burrow through the concrete to make a home. 
19. Concrete has multiple design possibilities.
20. Concrete can be used to achieve optimum environmental performance. 
21. As it is recyclable, it is possible to use it for addition.
22. High-performance concrete is used to build bridges.
23. Concrete is able to accommodate steel reinforcements in gates, tunnel lines, electrical controls.
24. A concrete floor can be stamped to create an attractive surface. It can admit natural light during the day and transmit artificial light after work.
25. Concrete is used in driveways and patios

• ENGINEERING PROPERTIES OF CONCRETE

Strength

Strength of concrete are of the following types:

1. Compressive strength
2. Tensile strength
3. Flexural strength
4. Shear strength

Concrete is very weak in tension. The tensile strength of ordinary concrete ranges from about 7 to 10 percent of the compressive strength.

The flexural strength of plain concrete is almost wholly dependent upon the tensile strength. However, experiments show that the modulus of rupture is considerably greater than the strength in tension.

It is the real determining factor in the compressive strength of short columns. The average strength of concrete in direct shear varies from about half of the compressive strength for rich mixtures to about 0.8 of the compressive strength for lean mixtures.

Workability

The strength of concrete of a given mix proportion is very seriously affected by the degree of its compaction. It is therefore vital that the consistency of the mix be such that the concrete can be transported, placed, and finished sufficiently easily, and without segregation. A concrete satisfying these conditions is said to be workable.

Factors affecting the workability of concrete are:

• Water Content
• Mix Proportions
• Size of Aggregates
• Shape of Aggregates
• Grading of Aggregates
• Surface Texture of Aggregates
• Use of Admixtures
• Use of Supplementary Cementitious Materials
• Time
• Temperature

Elastic Properties

Concrete is not perfectly elastic for any range of loading, an appreciable permanent setting taking place for even low loads. The deformation is not proportional to the stress at any stage of loading. The elastic properties of concrete vary with the richness of the mixture, and with the intensity of the stress. They also vary with the age of concrete.

Durability

Durability is the property of concrete to withstand the condition for which it has been designed, without deterioration over a period of years. Lack of durability can be caused by external agents arising from the environment or by internal agents within the concrete.

Impermeability

Penetration of concrete by materials in solution may adversely affect its durability, for instance, when Ca(OH)2 is being leached out or an attack by aggressive liquids (acids) takes place. Permeability has an important bearing on the vulnerability of concrete to water, and frost. In the case of reinforced cement concrete, the penetration of moisture, and air will result in the corrosion of steel. This leads to an increase in the volume of the steel, resulting in cracking, and spalling of the concrete. Permeability of concrete is also of importance for liquid retaining, and hydraulic structures

Segregation

The tendency of separation of coarse aggregate grains from the concrete mass is called segregation. It increases when the concrete mixture is lean and too wet. It also increases when a rather large, and rough-textured aggregate is used. The phenomenon of segregation can be avoided as follows.

1. Addition of little air-entraining agents in the mix.
2. Restricting the amount of water to the smallest possible amount.
3. All the operations like handling, placing, and consolidation must be carefully conducted.
4. Concrete should not be allowed to fall from large heights.

Bleeding

The tendency of water to rise to the surface of freshly laid concrete is known as bleeding. The water rising to the surface carries with it, particles of sand, and cement, which on hardening form a scum layer is popularly known as laitance. Concrete bleeding can be checked by adopting the following measures.

1. By adding more cement
2. By using more finely ground cement
3. By properly designing the mix, and using the minimum quantity of water
4. By using little air entraining agent
5. By increasing the finer part of fine aggregate

Fatigue

Plain concrete when subjected to flexure, exhibits fatigue. The flexure resisting ability of concrete of a given quality is indicated by an endurance limit whose value depends upon the number of repetitions of stress. In concrete pavement design, the allowable flexural working stress is limited to 55% of the modulus of rupture.

STEEL

Some vital utilization of steels are given below:

1. Steel is environment-friendly & sustainable. It posses great durability.
2. Compared to other materials, steel requires a low amount of energy to produce lightweight steel construction. 
3. Steel is the world’s most recycled material which can be recycled very easily. Its unique magnetic properties make it an easy material to recover from the stream to be recycled.
4. Steel can be designed into various forms. It gives better shape, and edge than iron which is used to make weapons.
5. Engineering steels are used for general engineering and manufacturing sectors.
6. Steel is highly used in the automobile industry. Different types of steel are used in a car body, doors, engine, suspension, and interior. The average 50% of a car is made of steel. 
7. Steel reduces CO2 emissions. 
8. All types of energy sectors demand steel for infrastructure, and resource extraction.
9. Stainless steels are used to produce offshore platforms and pipelines.
10. Steels are used for packaging and protecting goods from water, air, and light exposure.
11. Most of the household appliances like fridges, TV, oven, sinks, etc are made of steel.
12. Steels are used for producing industrial goodies like farm vehicles and machines. 
13. Stainless steel is used as a cutlery material. 
14. Because of its easily welding capability, and attractive finishing, steel has become a prominent feature in modern architecture. 
15. Stainless steel gives a hygienic environment. That’s why it is used for surgical implants. 
16. Steel has a wider range of temperature which is used to make large sheets.
17. Renewable energy resources like solar, hydro, and wind power use stainless steel components.
18. Mild steel is used for building construction. It is also a highly favored building frame material.

• ENGINEERING PROPERTIES OF STEEL

1. Tensile strength

The stress-strain curve for the steel is generally obtained by conducting a tensile test on any standard steel specimen. The tensile strength of the steel can be defined in terms of yield strength, and ultimate strength.

Hardness is regarded as the resistance of any material to identification and scratching. This is generally determined by forcing an indenter on to the surface. The resultant deformation steel is both elastic, and plastic. The different methods to find out the hardness of metal which include the Brinell hardness test, Vicker’s hardness test, and Rockwell hardness test.

There is the possibility of microscopic cracks in a material or the material may develop such cracks as a result of several cycles of loading. These cracks may result in a sudden collapse of the structure, and it is very dangerous. Therefore to ensure that this should not happen, materials in which the cracks grow slowly are preferred. These types of steel are known as notch-tough steels and the amount of energy it absorbs is measure by impacting the notched specimen.

A component of the structure, which is designed to carry a single monotonically static load, may fail if the same load is applied cyclically a large number of times. If the example of a thin rod is considered, it bent back, and forth beyond yielding fails after a few cycles of such repeated bending. This type of failure is termed as fatigue failure. Examples: bridges, cranes, offshore structures, slender towers, etc.

Corrosion is the procedure in which oxidation of metal in a normal atmospheric condition owing to the excessive presence of moisture, and oxygen in the air. Corrosion of the metal is a very natural, and rapid phenomenon in areas of high humidity, and places closer to saline water. Therefore the efforts to be made to control the corrosion by using galvanize and epoxy-coated reinforcement bars but failed in practical usage due to the risk of disbanding, causing accelerated corrosion. Corrosion resistance elements such as copper, phosphorus, and chromium are added inappropriate measure to the metal which results in corrosion resistance steel.

Q.7 What are the types of loads on buildings?

INTRODUCTION

Simply, loads are some sort of force. Major types of loads:

1. Dead loads. (red arrow) - Exerted by the weight of the element of the structure.
2. Live loads. (rest arrow) - Exerted by any temporary force acting on the structure Loads in a simple structure

DEAD LOADS

 Dead Loads are those loads that are considered to act permanently; they are "dead," stationary, and unable to be removed. The self-weight of the structural members normally provides the largest portion of a dead load of a building. Exerted by the weight of the element of the structure

LIVE LOADS

Live Loads are not permanent and can change in magnitude. They include items found within a building LIVE LOADS All the arrows indicate the live loads unless the red one.

Wind load

The wind's relatively large projected areas can develop substantial forces in the structure.

Earthquake loads are another lateral live load.

They are very complex, uncertain, and potentially more damaging than wind loads. LIVE LOADS EARTHQUAKE LOADS: Mass tends to remain in its original position, deformation due to sudden ground moving take place at the base

POINT LOAD OR CONCENTRATED LOAD

The load concentrated at one point is called point load. The unit of point load is N or kN. e.g. 20kN,100N etc. W1 and W2 are point loads.

UNIFORMLY DISTRIBUTED LOAD

Load uniformly distributed on a certain length of a beam is called uniformly distributed load. It is written as u.d.l. It is shown by w. Unit of u.d.l. Is kN/m or N/m.

UNIFORMLY VARYING LOAD

This type of load gradually increases or decreases the length of the beam. It is also called a triangular load.

Q.8 Explain Load Bearing construction?

Load-bearing walls in small buildings 

In the case of a small building, brick walls will often have the ability to also support other parts of the building (that is, to be load-bearing without any particular modification). Masonry has traditionally been used as the principal loadbearing system for buildings, ranging from small single-storey housing o fairly tall commercial, and industrial buildings. In most cases, some thought will have to be given to the form and detailing of the walls to make sure they are suitable to carry these loads. In order to carry vertical loads, the wall has to be continuous from top to bottom. Ideally, openings should be rather narrow, and in line vertically, rather than wide or haphazardly located on the elevation.

Since walls rely on intersecting with each other to provide some of their stability, continuous vertical opening would turn the wall into a series of isolated piers. This layout would only be efficient if the floors each served to tie the separate piers together at each level.

Openings in load-bearing walls 

The Building Code of Australia requires lintels over the openings in loadbearing walls to have the same Fire resistance Level (RFL) as the wall itself unless it falls within the scope of certain exemptions. The exemptions allow non-firerated lintels in single storey buildings and in other buildings where the span does not exceed 1.8m, and the wall or leaf is not more than 150mm thick. In practice, this is another reason for limiting the width of the openings in load-bearing walls.

The layout of walls to support floor loads

In order to use the walls to support floor loads, we first have to consider a suitable span for the floor structure. Conventional timber, joist floors seldom span more than 4 or 5 meters. Domestic concrete slabs only improve on these spans a little, while commercials flat concrete slabs commonly cover 6 to 8 meters between supports and floors using steel or concrete beams can extend these limits a little. Slabs systems can be continuously supported on walls, but beam systems usually need thickened piers under the beams.

Q.9 Explain the Functions of the Foundation?

1. Reduction of load intensity

Foundations distribute loads of the super-structure, to a larger area so that the intensity of the load at its base (i.e. total load divided by the total area) does not exceed the safe bearing capacity of the sub-soil. In the case of deep foundations, it transmits the superimposed loads to the sub-soil both through side friction as well as through end bearing.

2.     Even distribution of load

Foundations distribute the non-uniform load of the super-structure evenly to be sub-soil. For example, two columns carrying unequal loads can have a combined footing which may transmit the load to sub-soil evenly with uniform soil pressure. Due to this, unequal or differential settlements are minimized.

3.     Provision of level surface

Foundations provide leveled, and hard surface over which the super-structure can be built.

4.     Lateral stability

It anchors the super-structure to the ground, thus imparting lateral stability to the super-structure. The stability of the building, against sliding, and overturning, due to horizontal forces (such as wind, earthquake, etc.) is increased due to foundations.

5.     Safety against undermining

It provides structural safety against undermining or scouring due to burrowing animals and flood water.  

6.     Protection against soil movements

Special foundation measures prevent or minimize the distress (or cracks) in the super-structure, due to expansion or contraction of the sub-soil because of moisture movement.

Q.10 Define Safe bearing capacity, Ultimate bearing capacity or Gross bearing capacity, Net ultimate bearing capacity?

Safe bearing capacity: It is the bearing capacity after applying the factor of safety (FS). These are of two types, Safe net bearing capacity (qns): Is the net soil pressure that can be safely applied to the soil considering only shear failure. It is given by,

Ultimate bearing capacity or Gross bearing capacity (qu): It is the least gross pressure that will cause the shear failure of the supporting soil immediately below the footing.

Net ultimate bearing capacity (qun ): It is the net pressure that can be applied to the footing by external loads that will just initiate failure in the underlying soil. It is equal to ultimate bearing capacity minus the stress due to the weight of the footing, and any soil or surcharge directly above it. Assuming the density of the footing (concrete), and soil (Ƴ ) are close enough to be considered equal, then where, is the depth of the footing,

The factor of safety (FoS)

It is the ability of a system's structural capacity to be viable beyond its expected or actual loads. An FoS may be expressed as a ratio that compares absolute strength to the actual applied load, or it may be expressed as a constant value that a structure must meet or exceed according to law, specification, contract, or standard.

Q.11 Draw a neat sketch of a cross-section through load-bearing wall?

Unit 1

Building, Planning, and Construction

Q.1 What are the Branches in civil engineering?

Sol:

Civil engineering is the design, implementation, and maintenance of public works. This involves facilities and structures such as arenas, large scale monuments, government buildings, transportation routes as well as other structures. Engineers will either work for the city or for a private firm that has been hired by the city. Some civil engineers work in the private sector on projects for independent companies. There are several types of civil engineering. A civil engineer can specialize in a number of different civil engineering branches. Those branches are described briefly below:

• Structural Engineering
• Geotechnical Engineering
• Environmental Engineering
• Transportation Engineering
• Water Resource Engineering
• Earthquake Engineering
• Material Engineering
• Construction Engineering
• Surveying
• Municipal Engineering
• Coastal Engineering
• Tunnel Engineering

Scope of Civil Engineering Civil engineering is the oldest branch of engineering which is growing right from the stone age of civilization. American society of civil engineering defines civil engineering as the profession in which a knowledge of the mathematical, and physical sciences gained by study, experience, and practice is applied with judgment to develop ways to utilize economically the materials and forces of nature for the progressive well being of man.

Q.2 What are the Roles of Civil Engineers in various construction activities?

Sol:

A civil engineer has to conceive, plan, estimate, get approval, create, and maintain all civil engineering activities.

A civil engineer has a very important role in the development of the following infrastructure:

• Measure, and map the earth’s surface.
• Plan new townships  and extension of existing towns
• Build suitable structures for the rural, and urban areas for various utilities
• Build tanks and dams to exploit water resources.
• Build river navigation and flood control projects.
• Provide, and maintain communication systems like roads, railways, harbours and airports
• Purify, and supply water to the needy areas like houses, schools, offices, etc.
• Build canals and distributaries to take water to agricultural fields
• Devise systems for control, and efficient flow of traffic
• Provide, and maintain a solid, and wastewater disposal system
• Monitor land, water, and air pollution, and take measures to control them

Fast-growing industrialization has put heavy responsibilities on civil engineers to preserve, and protect the environment.

Q.3 Explain the Selection of site, and its factors affecting selection of site?

Sol:

Site selection indicates the practice of new facility location, both for business and government. Site selection involves measuring the needs of a new project against the merits of potential locations. The practice came of age during the 20th century, as governments and corporate operations expanded to new geographies on a national, and international scale

Factors affecting the selection of site

The site for a residential building should present a peaceful environment, good landscape, sun for the most part of the day, and uninterrupted flow of natural air. The following factors need to be studied in-depth while selecting the site for a residential building:

• Topography
• Nature of sub-soil
• Position of the groundwater table
• Facilities
• Neighbourhood
• Undesirable things near the site
• Vegetation
• The shape of the site
• Availability of men, and materials
• Proximity to sea-shore, river or lake or the place of natural beauty

Q.4 Define  F.S.I., Carpet area, Plinth area?

Sol:

F.S.I.,

FSI stands for Floor Space Index also known as Floor Area Ratio (FAR). FSI means the ratio between the area of a covered floor (Built-up Area) to the area of that plot (l, and) on which a building stands.

It is calculated by dividing the total covered built-up area on all floors of a building by the area of the plot it stands on. For instance, if you have 1,000 square feet of l, and on which you want to build a residential or commercial building, and the FSI in your locality is 1.5, then you could build up to 1,500 sq.

Carpet area

The carpet area is the area that can be used to spread a carpet inside the house. It is the net usable area of the apartment. It includes the thickness of the internal wall but excludes the balcony or terrace. Technically, the distance between the inner walls is a carpet area.

Plinth area

The plinth area is the covered built-up area measured at the floor level of any storey or the floor level of the basement. The plinth area is also called a built-up area and is the entire area occupied by the building including internal, and external walls. The plinth area is generally 10-20% more than the carpet area.

Q.5 Explain briefly the cost of the building?

Sol:

Cost reduction through adhoc methods

Foundation

• Normally the foundation cost comes to about 10 to 15% of the total building, and usually foundation depth of 3 to 4 ft. Is adopted for a single or double store building, and also the concrete bed of (15 Cms.) is used for the foundation which could be avoided.

• It is recommended to adopt a foundation depth of 2 ft. (0.6m) for normal soil like gravely soil, red soils, etc., and use the un-coursed rubble masonry with the bond stones and good packing. Similarly, the foundation width is rationalized to 2 ft. (0.6m). To avoid cracks formation in the foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.

• It is further suggested adopt an arch foundation in ordinary soil for effecting a reduction in construction cost up to 40%. This kind of foundation will help in bridging the loose pockets of soil that occurs along the foundation.

• In the case of black cotton, and other soft soils it is recommended to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.

Plinth

• It is suggested to adopt 1 ft. Height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided, and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%. It is necessary to take the precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface, and crack formation.

Walling

• Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building, and 41/2 ” for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls

Rat – trap bond wall

• It is a cavity wall construction with the added advantage of thermal comfort, and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce the material cost of bricks by 25%, and about 10to 15% in the masonry cost. By adopting a rat-trap bond method one can create an aesthetically pleasing wall surface, and plastering can be avoided.

Concrete block walling

• In view of high energy consumption by burnt brick it is suggested to use a concrete block (block hollow, and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of the wall resulting in a higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.

Soil cement block technology

• It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy-efficient method of construction where the soil is mixed with 5%, and above the cement, and pressed in h, and operated machine, and cured well, and then used in the masonry. This masonry doesn’t require plastering on both sides of the wall. The overall economy that could be achieved with the soil-cement technology is about 15 to 20% compared to the conventional method of construction.

Doors and windows

• It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%. Similarly for shutters commercially available block boards, fiber or wooden practical boards, etc., shall be used for reducing the cost by about 25%. By adopting brick jelly work, and precast components effective ventilation could be provided to the building, and also the construction cost could be saved up to 50% over the window components.

Lintals and Chajjas

• The traditional R.C.C. Lintels which are costly can be replaced by brick arches for small spans and save construction costs up to 30 to 40% over the traditional method of construction. By adopting arches of different shapes a good architectural pleasing appearance can be given to the external wall surfaces of the brick masonry.

Roofing

• Normally(12.5 cms) thick R.C.C. Slabs are used for roofing of residential buildings. By adopting rationally designed in situ construction practices like filler slabs and precast elements the construction cost of roofing can be reduced by about 20 to 25%.

Filler slabs

• They are normal RCC slabs where bottom half (tension) concrete portions are replaced by filler materials such as bricks, tiles, cellular concrete blocks, etc. These filler materials are so placed as not to compromise structural strength, result in replacing unwanted, and non-functional tension concrete, thus resulting in economy. These are safe, sound, and provide aesthetically pleasing pattern ceilings and also need no plaster.

Finishing Work

• The cost of finishing items like sanitary, electricity, painting, etc., varies depending upon the type, and quality of products used in the building, and its cost reduction is left to the individual choice and liking.

Prevention of slum

• The formation of the slum is a very slow process and extreme care should be exercised by the authority to prevent the springing up of new slums in the town.
• Some of the important measures which can be taken to effectively prevent slum formation.

 Cheap Housing

• Sufficient no of cheap housing should be made available to the poor people.

Compulsion To Employers

• The employer of a good number of labourers may be compelled or forced to provide housing accommodation for their staff.

Construction of Buildings

• Certain rules and regulations may be framed, and strictly enforced to restrict the coming up of buildings of subnormal standards

Maintenance, and Repair

• The responsibility of maintenance, and carrying out repair should be fixed and defined in housing codes or acts. It then becomes the duty of the landlord or tenant to keep an existing building in a good condition.

Social Education

• It is possible to check the growth of slums by carrying out effective social education of the slum dwellers, the social education makes the slum dweller conscious of the evils of the slum, and a great improvement in the living standard of slum dwellers could be achieved

Unauthorized Construction

• It is absolutely necessary to arrest immediately the unauthorized construction in the form of huts and temporary structures on a vacant piece of l, and.
• The authorities concerned should take drastic action in demolishing and removing such unauthorized construction.

Q.6 Briefly explain the Classification, properties and uses of materials - bricks, stones, sand, aggregates, cement, concrete, steel?

Sol:

BRICKS

Constituents of good brick earth: Bricks are the most commonly used construction material. Bricks are prepared by moulding clay in rectangular blocks of uniform size and then drying, and burning these blocks. In order to get a good quality brick, the brick earth should contain the following constituents.

• Silica
• Alumina
• Lime
• Iron oxide
• Magnesia

Brick plays a very important role in the field of civil engineering construction. Bricks are used as an alternative of stones in construction purposes.

• USES OF CEMENT

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) use as an aggregate in concrete
6. Manufacture of surki (powdered bricks) to be used in lime plaster, and lime concrete

Classification of Bricks as per constituent materials

There are various types of bricks used in masonry

• Common Burnt Clay Bricks
• Sand Lime Bricks (Calcium Silicate Bricks)
• Engineering Bricks
• Concrete Bricks
• Fly ash Clay Bricks

Common Burnt Clay Bricks

Common burnt clay bricks are formed by pressing in moulds. Then these bricks are dried and fired in a kiln. Common burnt clay bricks are used in general work with no special attractive appearances. When these bricks are used in walls, they require plastering or rendering.

Sand Lime Bricks

 Sand lime bricks are made by mixing sand, fly ash, and lime followed by a chemical process during wet mixing. The mix is then moulded under pressure forming the brick. These bricks can offer advantages over clay bricks such as their colour appearance is grey instead of the regular reddish colour. Their shape is uniform and presents a smoother finish that doesn’t require plastering. These bricks offer excellent strength as a load-bearing member.

Engineering Bricks

Engineering bricks are bricks manufactured at extremely high temperatures, forming a dense, and strong brick, allowing the brick to limit strength, and water absorption. Engineering bricks offer excellent load-bearing capacity damp-proof characteristics and chemical resisting properties. Concrete Bricks Concrete bricks are made from solid concrete. Concrete bricks are usually placed in facades, fences and provide an excellent aesthetic presence. These bricks can be manufactured to provide different colours as pigmented during its production.

Fly Ash Clay Bricks

Fly ash clay bricks are manufactured with clay, and fly ash, at about 1,000 degrees C. Some studies have shown that these bricks tend to fail poor produce pop-outs when bricks come into contact with moisture, and water, causing the bricks to expand.

• ENGINEERING PROPERTIES OF CEMENT

To know the quality of bricks following 7 tests can be performed. In these tests, some are performed in a laboratory, and the rest are on the field.

• Compressive strength test
• Water Absorption test
• Efflorescence test
• Hardness test
• Size, Shape, and Colour test
• Soundness test

Structure test Compressive strength test

This test is done to know the compressive strength of brick. It is also called the crushing strength of brick. Generally, 5 specimens of bricks are taken to the laboratory for testing and tested one by one. In this test, a brick specimen is put on a crushing machine and applied pressure till it breaks. The ultimate pressure at which brick is crushed is taken into account. All five brick specimens are tested one by one, and the average result is taken as the brick’s compressive/crushing strength.

Water Absorption test In this test bricks are weighed in dry condition, and let immersed in freshwater for 24 hours. After 24 hours of immersion, those are taken out from the water and wipe out with a cloth. Then brick is weighed in wet condition. The difference between weights is the water absorbed by brick. The percentage of water absorption is then calculated. The less water absorbed by brick the greater it's quality. Good quality brick doesn’t absorb more than 20% water of its own weight.

Efflorescence test The presence of alkalies in bricks is harmful, and they form a grey or white layer on the brick surface by absorbing moisture. To find out the presence of alkalis in bricks this test is performed. In this test, a brick is immersed in freshwater for 24 hours and then it’s taken out from the water, and allowed to dry in shade. If the whitish layer is not visible on the surface it proofs the absence of alkalis in brick. If the whitish layer visible about 10% of the brick surface then the presence of alkalis is inacceptable range. If that is about 50% of the surface then it is moderate. If the alkalies’ presence is over 50% then the brick is severely affected by alkalies.

Hardness test

In this test, a scratch is made on a brick surface with a hard thing. If that doesn’t leave any impression on brick then that is good quality brick.

Size, shape, and colour test

In this test randomly collected 20 bricks are staked along lengthwise, width-wise, and height-wise, and then those are measured to know the variation of sizes as per standard. Bricks are closely viewed to check if its edges are sharp, and straight, and uniform in shape. A good quality brick should have bright, and uniform colour throughout.

Soundness test

In this test, two bricks are held by both hands and struck with one another. If the bricks give a clear metallic ringing sound and don’t break then those are good quality bricks.

Structure test In this test a brick is broken or a broken brick is collected, and closely observed. If there are any flaws, cracks, or holes present on that broken face then that isn’t good quality brick.

STONES

• USES OF STONES

1. Stone masonry is used for the construction of foundations, walls, columns and arches.
2. Stones are used for flooring.
3. Stone slabs are used as damp proof courses, lintels and even as roofing materials.
4. Stones with good appearance are used for the face works of buildings. Polished marbles and granite are commonly used for face works.
5. Stones are used for paving roads, footpaths and open spaces around the buildings.
6. Stones are also used in the constructions of piers and abutments of bridges, dams and retaining walls.
7. Crushed stones with graved are used to provide a base course for roads. When mixed with tar they form a finishing coat.

Crushed stones are used in the following works also:

1. As a basic inert material in concrete.
2. For making artificial stones and building blocks.
3. As railway ballast.

• ENGINEERING PROPERTIES OF STONES

1. STRUCTURE

The structure of the stone may be stratified (layered) or unstratified. Structured stones should be easily dressed, and suitable for the superstructure. Unstratified stones are hard and difficult to dress. They are preferred for the foundation works.

2. TEXTURE

Fine-grained stones with homogeneous distribution look attractive, and hence they are used for carving. Such stones are usually strong, and durable.

3. DENSITY

Denser stones are stronger. Lightweight stones are weak. Hence stones with a specific gravity less than 2.4 are considered unsuitable for buildings.

4. APPEARANCE

A stone with uniform and attractive colour is durable if grains are compact. Marble and granite get a very good appearance, when polished. Hence they are used for face works in buildings.

5. STRENGTH

Strength is an important property to be looked into before selecting stone as a building block. Indian standard code recommends, minimum crushing strength of 3.5 N/mm2 for any building block

6. HARDNESS

It is an important property to be considered when the stone is used for flooring and pavement. The coefficient of hardness is to be found by conducting a test on the standard specimen in Dory’s testing machine. For road works coefficient of hardness should be at least 17. For building works stones with a coefficient of hardness less than 14 should not be used.

7. PERCENTAGE WEAR

It is measured by an attrition test. It is an important property to be considered in selecting aggregate for road works and railway ballast. A good stone should not show the wear of more than 2%.

8. POROSITY, AND ABSORPTION

All stones have pores and hence absorb water. The reaction of water with stone causes disintegration. The absorption test is specified as the percentage of water absorbed by the stone when it is immersed underwater for 24 hours. For a good stone, it should be as small as possible and in no case more than 5.

9. WEATHERING

Rain, and wind cause loss of good appearance of stones. Hence stones with good weather resistance should be used for face works.

10. TOUGHNESS

The resistance to impact is called toughness. It is determined by the impact test. Stones with a toughness index of more than 19 are preferred for road works. Toughness index 13 to 19 is considered as medium tough, and stones with toughness index less than 13 are poor stones.

11. RESISTANCE TO FIRE

Sandstones resist fire better. Argillaceous materials, though poor in strength, are good in resisting fire.

12. EASE IN DRESSING

The cost of dressing contributes to the cost of stone masonry to a great extent. The dressing is easy in stones with lesser strength. Hence an engineer should look into sufficient strength rather than high strength while selecting stones for building works.

13. SEASONING

The stones obtained from the quarry contain moisture in the pores. The strength of the stone improves if this moisture is removed before using the stone. The process of removing moisture from pores is called seasoning. The best way of seasoning is to allow it to the action of nature for 6 to 12 months. This is very much required in the case of laterite stones.

SAND

Sand is a mixture of small grains of rock, and granular materials which are mainly defined by size, being finer than gravel, and coarser than silt., and ranging in size from 0.06 mm to 2 mm. Particles that are larger than 0.0078125 mm but smaller than 0.0625 mm are termed silt.

Sand is made by erosion or broken pebbles and weathering of rocks, which is carried by seas or rivers., and freezing, and thawing during the winter break rock up the sand will be made. Sometimes Sand on beaches can also be made by small broken-up pieces of coral, bone, and shell, which are broken up by predators and then battered by the sea, and even tiny pieces of glass from bottles discarded in the sea, and other mineral materials or the bones of fishes or other oceanic animals. Sand can be also considered as a textural class of soil or soil type.

In the real world, there are a lot of situations where we can find uses for sand. The followings are the common sand uses.

1. We can use sand to filter water; it works like an abrasive.
2. We can use sand to give a grip to our painting or wall art by combining 2 cups of paint with a ¾ cup of sand.
3. People make sandpaper by gluing sand to a paper.
4. While bunging metal, we can mix sand with clay binder for frameworks used in the foundries.
5. Sand can be used for cleaning up oil leaks or any spill by dredging sand on that spill. The material will form clumps by soaking up, and we can quickly clean the mess.
6. Sand can be used as a road base which is a protective layer underneath all roads
7. Industrial sand is used to make glass, as foundry sand, and as abrasive sand.
8. One creative usage of sand is serving as a candle holder. We can try putting some sand before pouring tea light or any candle in a glass. It holds the candle still, and refrain the candle from rolling by giving it an excellent decoration.
9. Adds texture, and aesthetic appeal to space.
10. Sand is most pure to handle, promptly available, and economically wise.
11. We can make children’s sandpit to keep the play areas safer. It is quite inexpensive as well.
12. We use sand in aquariums, fabricating artificial fringing reefs, and in human-made beaches
13. Sandy soils are ideal for growing crops, fruits and vegetables like watermelon, peaches, peanuts, etc.
14. Sand can light a path by filling mason jars with sand, and tea light which is another inexpensive way to make a walkway glow.
15. Sand can be used for cleaning narrow neck receptacle by putting a little sand, and warm soapy water in the container.
16. We can keep an item steady which needs repairing by using sand. Burying the broken pieces under sand grains helps to hold the elements together while gluing.
17. Sand helps to improve resistance (and thus traffic safety) in icy or snowy conditions.
18. We need sand in the beaches where tides, storms, or any form of preconceived changes to the shoreline crumble the first sand.
19. Sand containing silica is used for making glass in the automobile, and food industry- even household products for the kitchen.
20. Sand is strong str, and which is used for plaster, mortar, concrete, and asphalt.
21. The usual bricks formulated of clay only is way weaker, and lesser in weight than blocks made of clay mixed with sand

Followings are the desirable properties of sand: 

• Should be completely inert. (i.e., should not have any chemical activity).
• Grains should be sharp, strong & angular.
• Should not contain any hygroscopic salts (i.e., CaCl2, MgCl2, etc.).
• Should not contain clay & silt; usually, 3-4% clay & silt is ordinarily permitted for practical reasons.
• There should be no organic matter.

AGGREGATES

Aggregate is an aggregation of non-metallic minerals obtained in particulate form, and can be processed, and used for civil, and highway engineering construction.

Aggregates are mainly classified into two categories:

1. Fine Aggregate
2. Coarse Aggregate

Aggregates are used in concrete to provide economy in the cost of concrete. Aggregates act as filler only. These do not react with cement and water. But there are properties or characteristics of aggregate which influence the properties of the resulting concrete mix. These are as follows.

1. Composition
2. Size & Shape
3. Surface Texture
4. Specific Gravity
5. Bulk Density
6. Voids
7. Porosity & Absorption
8. Bulking of Sand
9. Fineness Modulus of Aggregate
10. Surface Index of Aggregate
11. Deleterious Material
12. Crushing Value of Aggregate
13. Impact Value of Aggregate
14. Abrasion Value of Aggregate

1. COMPOSITION

Aggregates consisting of materials that can react with alkalies in cement, and cause excessive expansion, cracking, and deterioration of concrete mix should never be used. Therefore, it is required to test aggregates to know whether there is a presence of any such constituents in aggregate or not.

2. SIZE & SHAPE

The size and shape of the aggregate particles greatly influence the quantity of cement required in the concrete mix, and hence ultimately the economy of concrete. For the preparation of an economical concrete mix, one should use the largest coarse aggregates feasible for the structure. IS-456 suggests the following recommendation to decide the maximum size of coarse aggregate to be used in the P.C.C & R.C.C mix.

The maximum size of aggregate should be less than

• One-fourth of the minimum dimension of the concrete member.
• One-fifth of the minimum dimension of the reinforced concrete member.
• The minimum clear spacing between reinforced bars or 5 mm less than the minimum cover between the reinforced bars and form, whichever is smaller for heavily reinforced concrete members such as the ribs of the main bars.

3. SURFACE TEXTURE

The development of hard bond strength between aggregate particles and cement paste depends upon the surface texture, surface roughness, and surface porosity of the aggregate particles. If the surface is rough but porous, maximum bond strength develops. In porous surface aggregates, the bond strength increases due to the setting of cement paste in the pores.

4. SPECIFIC GRAVITY

The ratio of the weight of oven-dried aggregates maintained for 24 hours at a temperature of 100 to 1100C, to the weight of an equal volume of water displaced by saturated dry surface aggregate is known as the specific gravity of aggregates.

5. BULK DENSITY

It is defined as the weight of the aggregate required to fill a container of unit volume. It is generally expressed in kg/liter.

Bulk density of aggregates depends upon the following 3 factors.

• Degree of compaction
• Grading of aggregates
• The shape of aggregate particles

6. VOIDS

The empty spaces between the aggregate particles are known as voids. The volume of void equals the difference between the gross volume of the aggregate mass and the volume occupied by the particles alone.

7. POROSITY & ABSORPTION

The minute holes formed in rocks during solidification of the molten magma, due to air bubbles, are known as pores. Rocks containing pores are called porous rocks. Water absorption may be defined as the difference between the weight of very dry aggregates and the weight of the saturated aggregates with surface dry conditions.

Depending upon the amount of moisture content in aggregates, it can exist in any of the 4 conditions.

• Very dry aggregate ( having no moisture)
• Dry aggregate (contain some moisture in its pores)
• Saturated surface dry aggregate (pores filled with moisture but no moisture on the surface)
• Moist or wet aggregates (pores are filled with moisture, and also having moisture on the surface)

8. BULKING OF SAND

It can be defined as an increase in the bulk volume of the quantity of sand (i.e. fine aggregate) in a moist condition over the volume of the same quantity of dry or completely saturated sand. The ratio of the volume of moist sand due to the volume of sand when dry is called the bulking factor.

9. FINENESS MODULUS

Fineness modulus is an empirical factor obtained by adding the cumulative percentages of aggregate retained on each of the standard sieves ranging from 80 mm to 150 microns and dividing this sum by 100.

Fineness modulus is generally used to get an idea of how coarse or fine the aggregate is. More fineness modulus value indicates that the aggregate is coarser, and a small value of fineness modulus indicates that the aggregate is finer.

10. SPECIFIC SURFACE OF AGGREGATE

The surface area per unit weight of the material is termed as a specific surface. This is an indirect measure of the aggregate grading. Specific surface increases with the reduction in the size of the aggregate particle. The specific surface area of the fine aggregate is very much more than that of coarse aggregate.

11. DELETERIOUS MATERIALS

Aggregates should not contain any harmful material in such a quantity so as to affect the strength, and durability of the concrete. Such harmful materials are called deleterious materials. Deleterious materials may cause one of the following effects

• To interfere with the hydration of cement
• To prevent the development of proper bond
• To reduce strength and durability
• To modify setting times

12. CRUSHING VALUE

The aggregates crushing value gives a relative measure of the resistance of an aggregate to crushing under gradually applied compressive load. The aggregate crushing strength value is a useful factor to know the behavior of aggregates when subjected to compressive loads.

13. IMPACT VALUE

The aggregate impact value gives a relative measure of the resistance of an aggregate to sudden shock or impact. The impact value of an aggregate is sometimes used as an alternative to its crushing value.

14. ABRASION VALUE OF AGGREGATES

The abrasion value gives a relative measure of the resistance of an aggregate to wear when it is rotated in a cylinder along with some abrasive charge.

CEMENT

Cement is a binder, a substance that sets and hardens and can bind other materials together. Cement used in construction can be characterized as being either hydraulic or non-hydraulic, depending upon the ability of the cement to be used in the presence of water. Non-hydraulic cement will not set-in wet conditions or underwater, rather it sets as it dries and reacts with carbon dioxide in the air. It can be attacked by some aggressive chemicals after setting. Hydraulic cement is made by replacing some of the cement in a mix with activated aluminium silicates, pozzolanas, such as fly ash. The chemical reaction results in hydrates that are not very water-soluble, and so are quite durable in water and safe from chemical attack. This allows setting in wet condition or underwater, and further protects the hardened material from chemical attack (e.g., Portland cement).

• USE OF CEMENT

• Cement mortar for Masonry work, plaster, and pointing, etc.
• Concrete for laying floors, roofs, and constructing lintels, beams, weather shed, stairs, pillars, etc.
• Construction for important engineering structures such as bridges, culverts, dams, tunnels, lighthouses, clocks, etc.
• Construction of water, wells, tennis courts, septic tanks, lamp posts, telephone cabins, etc.
• Making joints for joints, pipes, etc.
• Manufacturing of precast pipes, garden seats, artistically designed wens, flower posts, etc.
• Preparation of foundation, watertight floors, footpaths, etc.

• ENGINEERING PROPERTIES OF CEMENT

Fineness

• This test is carried out to check the proper grinding of cement. The fineness of cement particles may be determined either by a sieve test or permeability apparatus test.
• In the sieve test, the cement weighing 100 gm is taken, and it is continuously passed for 15 minutes through standard BIS sieve no. 9. The residue is then weighed, and this weight should not be more than 10% of the original weight.
• In the permeability apparatus test, a specific area of cement particles is calculated. This test is better than a sieve test. The specific surface acts as a measure of the frequency of particles of average size.

Compressive strength

• This test is carried out to determine the compressive strength of cement.
• The mortar of cement and sand is prepared in the ratio of 1:3.
• Water is added to mortar in a water cement ratio of 0.4.
• The mortar is placed in moulds. The test specimens are in the form of cubes and the moulds are of metals. For 70.6 mm, and 76 mm cubes, the cement required is 185gm, and 235 gm respectively.
• Then the mortar is compacted in a vibrating machine for 2 minutes and the moulds are placed in a damp cabin for 24 hours.
• The specimens are removed from the moulds and they are submerged in clean water for curing.
• The cubes are then tested in a compression testing machine at the end of 3daysand 7 days. Thus compressive strength was found out.

Consistency

• The purpose of this test is to determine the percentage of water required for preparing cement pastes for other tests.
• Take 300 gm of cement, and add 30 percent by weight or 90 gm of water to it.
• Mix water, and cement thoroughly.
• Fill the mould of the Vicat apparatus and the gauging time should be 3.75 to 4.25 minutes.
• Vicat apparatus consists of a needle is attached to a movable rod with an indicator attached to it.
• There are three attachments: square needle, plunger, and needle with an annular collar.
• The plunger is attached to the movable rod. The plunger is gently lowered on the paste in the mould.
• The settlement of the plunger is noted. If the penetration is between 5 mm to 7 mm from the bottom of the mould, the water added is correct. If not the process is repeated with different percentages of water till the desired penetration is obtained.

Setting time

• This test is used to detect the deterioration of cement due to storage. The test is performed to find out the initial setting time, and final setting time.
• Cement mixed with water and cement paste is filled in the Vicat mould.
• The square needle is attached to the moving rod of the Vicat apparatus.
• The needle is quickly released, and it is allowed to penetrate the cement paste. In the beginning, the needle penetrates completely. The procedure is repeated at regular intervals till the needle does not penetrate completely. (up to 5mm from bottom)
• Initial setting time equal to or less than 30min for ordinary Portland cement, and 60 min for low heat cement.
• The cement paste is prepared as above, and it is filled in the Vicat mould.
• The needle with an annular collar is attached to the moving rod of the Vicat apparatus.
• The needle is gently released. The time at which the needle makes an impression on the test block and the collar fails to do so is noted.
• The final setting time is the difference between the time at which water was added to cement and time as recorded in the previous step, and it is equal to or less than 10hours.

Soundness

• The purpose of this test is to detect the presence of uncombined lime in the cement.
• The cement paste is prepared.
• The mould is placed, and it is filled with cement paste.
• It is covered at the top by another glass plate. A small weight is placed at the top, and the whole assembly is submerged in water for 24 hours.
• The distance between the points of the indicator is noted. The mould is again placed in water, and heat is applied in such a way that the boiling point of water is reached in about 30 minutes. The boiling of water is continued for one hour.
• The mould is removed from the water, and it is allowed to cool down.
• The distance between the points of the indicator is again measured. The difference between the two readings indicates the expansion of cement, and it should not exceed 10 mm.

Tensile strength

• This test was formerly used to have an indirect indication of the compressive strength of cement.
• The mortar of sand and cement is prepared.
• The water is added to the mortar.
• The mortar is placed in briquette moulds. The mould is filled with mortar, and then a small heap of mortar is formed at its top. It is beaten down by a standard spatula till water appears on the surface. The same procedure is repeated for the other face of the briquette.
• The briquettes are kept in a damp for 24 hours and carefully removed from the moulds.
• The briquettes are tested in a testing machine at the end of 3, and 7 days and the average is found out

CONCRETE

Concrete is a composite material composed mainly of water, aggregate, and cement. Often, additives and reinforcements are included in the mixture to achieve the desired physical properties of the finished material. When these ingredients are mixed together, they form a fluid mass that is easily moulded into shape. Over time, the cement forms a hard matrix that binds the rest of the ingredients together into a durable stone-like material with many uses.

• USES OF CONCRETE

1. It’s an important building product. Concrete is chosen over wood as a construction material.
2. It is a durable, and cost-effective material that is a necessity for underground use. 
3. Concrete is a sustainable choice for residential, and commercial projects. 
4. The strength of concrete increases over time. 
5. Concrete can hold up against weather conditions and is easy to maintain. 
6. It is budget-friendly to use everywhere. It is easy to repair & energy efficient.
7. Concrete is safe for building occupants.
8. Concrete is an inert material that doesn’t burn, mildew, or feed rot.
9. Its superior structural integrity provides an added degree of protection from severe weather as well as an earthquake.
10. Concrete walls and floors make a home a quiet place of rest, relaxation, and rejuvenation.
11. Concrete is produced from locally available materials and leaves a small environmental footprint while still providing high-level durability.
12. It is used as an aggregate in roadbeds or as granular materials while making new concrete. 
13. The concrete is fire resistant. It can resist the extreme level of flames and heat which is a good choice of the ceiling in a storage room. 
14. Concrete can be shaped in various forms when freshly mixed. 
15. Concrete isn’t sensitive to moisture.
16. It doesn’t release any volatile organic compounds into the environment-friendly air. 
17. Concrete gives a longer service life. 
18. It keeps the home safe from insects. It doesn’t attract insect pests and rodents. That’s why small animals cannot burrow through the concrete to make a home. 
19. Concrete has multiple design possibilities.
20. Concrete can be used to achieve optimum environmental performance. 
21. As it is recyclable, it is possible to use it for addition.
22. High-performance concrete is used to build bridges.
23. Concrete is able to accommodate steel reinforcements in gates, tunnel lines, electrical controls.
24. A concrete floor can be stamped to create an attractive surface. It can admit natural light during the day and transmit artificial light after work.
25. Concrete is used in driveways and patios

• ENGINEERING PROPERTIES OF CONCRETE

Strength

Strength of concrete are of the following types:

1. Compressive strength
2. Tensile strength
3. Flexural strength
4. Shear strength

Concrete is very weak in tension. The tensile strength of ordinary concrete ranges from about 7 to 10 percent of the compressive strength.

The flexural strength of plain concrete is almost wholly dependent upon the tensile strength. However, experiments show that the modulus of rupture is considerably greater than the strength in tension.

It is the real determining factor in the compressive strength of short columns. The average strength of concrete in direct shear varies from about half of the compressive strength for rich mixtures to about 0.8 of the compressive strength for lean mixtures.

Workability

The strength of concrete of a given mix proportion is very seriously affected by the degree of its compaction. It is therefore vital that the consistency of the mix be such that the concrete can be transported, placed, and finished sufficiently easily, and without segregation. A concrete satisfying these conditions is said to be workable.

Factors affecting the workability of concrete are:

• Water Content
• Mix Proportions
• Size of Aggregates
• Shape of Aggregates
• Grading of Aggregates
• Surface Texture of Aggregates
• Use of Admixtures
• Use of Supplementary Cementitious Materials
• Time
• Temperature

Elastic Properties

Concrete is not perfectly elastic for any range of loading, an appreciable permanent setting taking place for even low loads. The deformation is not proportional to the stress at any stage of loading. The elastic properties of concrete vary with the richness of the mixture, and with the intensity of the stress. They also vary with the age of concrete.

Durability

Durability is the property of concrete to withstand the condition for which it has been designed, without deterioration over a period of years. Lack of durability can be caused by external agents arising from the environment or by internal agents within the concrete.

Impermeability

Penetration of concrete by materials in solution may adversely affect its durability, for instance, when Ca(OH)2 is being leached out or an attack by aggressive liquids (acids) takes place. Permeability has an important bearing on the vulnerability of concrete to water, and frost. In the case of reinforced cement concrete, the penetration of moisture, and air will result in the corrosion of steel. This leads to an increase in the volume of the steel, resulting in cracking, and spalling of the concrete. Permeability of concrete is also of importance for liquid retaining, and hydraulic structures

Segregation

The tendency of separation of coarse aggregate grains from the concrete mass is called segregation. It increases when the concrete mixture is lean and too wet. It also increases when a rather large, and rough-textured aggregate is used. The phenomenon of segregation can be avoided as follows.

1. Addition of little air-entraining agents in the mix.
2. Restricting the amount of water to the smallest possible amount.
3. All the operations like handling, placing, and consolidation must be carefully conducted.
4. Concrete should not be allowed to fall from large heights.

Bleeding

The tendency of water to rise to the surface of freshly laid concrete is known as bleeding. The water rising to the surface carries with it, particles of sand, and cement, which on hardening form a scum layer is popularly known as laitance. Concrete bleeding can be checked by adopting the following measures.

1. By adding more cement
2. By using more finely ground cement
3. By properly designing the mix, and using the minimum quantity of water
4. By using little air entraining agent
5. By increasing the finer part of fine aggregate

Fatigue

Plain concrete when subjected to flexure, exhibits fatigue. The flexure resisting ability of concrete of a given quality is indicated by an endurance limit whose value depends upon the number of repetitions of stress. In concrete pavement design, the allowable flexural working stress is limited to 55% of the modulus of rupture.

STEEL

Some vital utilization of steels are given below:

1. Steel is environment-friendly & sustainable. It posses great durability.
2. Compared to other materials, steel requires a low amount of energy to produce lightweight steel construction. 
3. Steel is the world’s most recycled material which can be recycled very easily. Its unique magnetic properties make it an easy material to recover from the stream to be recycled.
4. Steel can be designed into various forms. It gives better shape, and edge than iron which is used to make weapons.
5. Engineering steels are used for general engineering and manufacturing sectors.
6. Steel is highly used in the automobile industry. Different types of steel are used in a car body, doors, engine, suspension, and interior. The average 50% of a car is made of steel. 
7. Steel reduces CO2 emissions. 
8. All types of energy sectors demand steel for infrastructure, and resource extraction.
9. Stainless steels are used to produce offshore platforms and pipelines.
10. Steels are used for packaging and protecting goods from water, air, and light exposure.
11. Most of the household appliances like fridges, TV, oven, sinks, etc are made of steel.
12. Steels are used for producing industrial goodies like farm vehicles and machines. 
13. Stainless steel is used as a cutlery material. 
14. Because of its easily welding capability, and attractive finishing, steel has become a prominent feature in modern architecture. 
15. Stainless steel gives a hygienic environment. That’s why it is used for surgical implants. 
16. Steel has a wider range of temperature which is used to make large sheets.
17. Renewable energy resources like solar, hydro, and wind power use stainless steel components.
18. Mild steel is used for building construction. It is also a highly favored building frame material.

• ENGINEERING PROPERTIES OF STEEL

1. Tensile strength

The stress-strain curve for the steel is generally obtained by conducting a tensile test on any standard steel specimen. The tensile strength of the steel can be defined in terms of yield strength, and ultimate strength.

Hardness is regarded as the resistance of any material to identification and scratching. This is generally determined by forcing an indenter on to the surface. The resultant deformation steel is both elastic, and plastic. The different methods to find out the hardness of metal which include the Brinell hardness test, Vicker’s hardness test, and Rockwell hardness test.

There is the possibility of microscopic cracks in a material or the material may develop such cracks as a result of several cycles of loading. These cracks may result in a sudden collapse of the structure, and it is very dangerous. Therefore to ensure that this should not happen, materials in which the cracks grow slowly are preferred. These types of steel are known as notch-tough steels and the amount of energy it absorbs is measure by impacting the notched specimen.

A component of the structure, which is designed to carry a single monotonically static load, may fail if the same load is applied cyclically a large number of times. If the example of a thin rod is considered, it bent back, and forth beyond yielding fails after a few cycles of such repeated bending. This type of failure is termed as fatigue failure. Examples: bridges, cranes, offshore structures, slender towers, etc.

Corrosion is the procedure in which oxidation of metal in a normal atmospheric condition owing to the excessive presence of moisture, and oxygen in the air. Corrosion of the metal is a very natural, and rapid phenomenon in areas of high humidity, and places closer to saline water. Therefore the efforts to be made to control the corrosion by using galvanize and epoxy-coated reinforcement bars but failed in practical usage due to the risk of disbanding, causing accelerated corrosion. Corrosion resistance elements such as copper, phosphorus, and chromium are added inappropriate measure to the metal which results in corrosion resistance steel.

Q.7 What are the types of loads on buildings?

INTRODUCTION

Simply, loads are some sort of force. Major types of loads:

1. Dead loads. (red arrow) - Exerted by the weight of the element of the structure.
2. Live loads. (rest arrow) - Exerted by any temporary force acting on the structure Loads in a simple structure

DEAD LOADS

 Dead Loads are those loads that are considered to act permanently; they are "dead," stationary, and unable to be removed. The self-weight of the structural members normally provides the largest portion of a dead load of a building. Exerted by the weight of the element of the structure

LIVE LOADS

Live Loads are not permanent and can change in magnitude. They include items found within a building LIVE LOADS All the arrows indicate the live loads unless the red one.

Wind load

The wind's relatively large projected areas can develop substantial forces in the structure.

Earthquake loads are another lateral live load.

They are very complex, uncertain, and potentially more damaging than wind loads. LIVE LOADS EARTHQUAKE LOADS: Mass tends to remain in its original position, deformation due to sudden ground moving take place at the base

POINT LOAD OR CONCENTRATED LOAD

The load concentrated at one point is called point load. The unit of point load is N or kN. e.g. 20kN,100N etc. W1 and W2 are point loads.

UNIFORMLY DISTRIBUTED LOAD

Load uniformly distributed on a certain length of a beam is called uniformly distributed load. It is written as u.d.l. It is shown by w. Unit of u.d.l. Is kN/m or N/m.

UNIFORMLY VARYING LOAD

This type of load gradually increases or decreases the length of the beam. It is also called a triangular load.

Q.8 Explain Load Bearing construction?

Load-bearing walls in small buildings 

In the case of a small building, brick walls will often have the ability to also support other parts of the building (that is, to be load-bearing without any particular modification). Masonry has traditionally been used as the principal loadbearing system for buildings, ranging from small single-storey housing o fairly tall commercial, and industrial buildings. In most cases, some thought will have to be given to the form and detailing of the walls to make sure they are suitable to carry these loads. In order to carry vertical loads, the wall has to be continuous from top to bottom. Ideally, openings should be rather narrow, and in line vertically, rather than wide or haphazardly located on the elevation.

Since walls rely on intersecting with each other to provide some of their stability, continuous vertical opening would turn the wall into a series of isolated piers. This layout would only be efficient if the floors each served to tie the separate piers together at each level.

Openings in load-bearing walls 

The Building Code of Australia requires lintels over the openings in loadbearing walls to have the same Fire resistance Level (RFL) as the wall itself unless it falls within the scope of certain exemptions. The exemptions allow non-firerated lintels in single storey buildings and in other buildings where the span does not exceed 1.8m, and the wall or leaf is not more than 150mm thick. In practice, this is another reason for limiting the width of the openings in load-bearing walls.

The layout of walls to support floor loads

In order to use the walls to support floor loads, we first have to consider a suitable span for the floor structure. Conventional timber, joist floors seldom span more than 4 or 5 meters. Domestic concrete slabs only improve on these spans a little, while commercials flat concrete slabs commonly cover 6 to 8 meters between supports and floors using steel or concrete beams can extend these limits a little. Slabs systems can be continuously supported on walls, but beam systems usually need thickened piers under the beams.

Q.9 Explain the Functions of the Foundation?

1. Reduction of load intensity

Foundations distribute loads of the super-structure, to a larger area so that the intensity of the load at its base (i.e. total load divided by the total area) does not exceed the safe bearing capacity of the sub-soil. In the case of deep foundations, it transmits the superimposed loads to the sub-soil both through side friction as well as through end bearing.

2.     Even distribution of load

Foundations distribute the non-uniform load of the super-structure evenly to be sub-soil. For example, two columns carrying unequal loads can have a combined footing which may transmit the load to sub-soil evenly with uniform soil pressure. Due to this, unequal or differential settlements are minimized.

3.     Provision of level surface

Foundations provide leveled, and hard surface over which the super-structure can be built.

4.     Lateral stability

It anchors the super-structure to the ground, thus imparting lateral stability to the super-structure. The stability of the building, against sliding, and overturning, due to horizontal forces (such as wind, earthquake, etc.) is increased due to foundations.

5.     Safety against undermining

It provides structural safety against undermining or scouring due to burrowing animals and flood water.  

6.     Protection against soil movements

Special foundation measures prevent or minimize the distress (or cracks) in the super-structure, due to expansion or contraction of the sub-soil because of moisture movement.

Q.10 Define Safe bearing capacity, Ultimate bearing capacity or Gross bearing capacity, Net ultimate bearing capacity?

Safe bearing capacity: It is the bearing capacity after applying the factor of safety (FS). These are of two types, Safe net bearing capacity (qns): Is the net soil pressure that can be safely applied to the soil considering only shear failure. It is given by,

Ultimate bearing capacity or Gross bearing capacity (qu): It is the least gross pressure that will cause the shear failure of the supporting soil immediately below the footing.

Net ultimate bearing capacity (qun ): It is the net pressure that can be applied to the footing by external loads that will just initiate failure in the underlying soil. It is equal to ultimate bearing capacity minus the stress due to the weight of the footing, and any soil or surcharge directly above it. Assuming the density of the footing (concrete), and soil (Ƴ ) are close enough to be considered equal, then where, is the depth of the footing,

The factor of safety (FoS)

It is the ability of a system's structural capacity to be viable beyond its expected or actual loads. An FoS may be expressed as a ratio that compares absolute strength to the actual applied load, or it may be expressed as a constant value that a structure must meet or exceed according to law, specification, contract, or standard.

Q.11 Draw a neat sketch of a cross-section through load-bearing wall?