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GLOBAL INSTITUTE OF TECHNOLOGY,

JAIPUR

RTU Paper Solution

Branch – Civil Engineering

Subject Name –Building Material &

Construction

Paper Code – 3CE4-07

Date of Exam – 24 Dec. 2019

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Global Institute of Technology, Jaipur ITS-1, IT Park, EPIP, Sitapura Jaipur 302022 (Rajasthan)

Solution III Sem University Examination 2019 Subject: Building Material and Construction Code: 3CE4-07 Semester: III; Year: II

Part A

Ans. 1 Role of Fly ash in Concrete-

Fly ash use in concrete improves the workability of plastic concrete, and the

strength and durability of hardened concrete. Fly ash use is also cost effective.

When fly ash is added to concrete, the amount of Portland cement may be reduced.

Ans. 2 Seasoning of Timber-

Seasoning is the process of drying timber to remove the bound moisture contained

in walls of the wood cells to produce seasoned timber. Seasoning can be achieved

in a number of ways, but the aim is to remove water at a uniform rate through the

piece to prevent damage to the wood during drying (seasoning degrade).

Ans. 3 Difference between Mild Steel and HYSD Steel

Mild steel is a plain low carbon steel without any alloying elements. It is very

ductile & is used as a structural steel for ordinary applications in civil

construction. HYSD is a special quality steel with much higher tensile strength

than the mild steel (30 to 40% stronger than mild steel).

Ans. 4 Different types of bond use in Brick Work

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

• Stretcher bond.

• Header bond.

• English bond and.

• Flemish bond.

Ans. 5 Comparison between Stone and Brick masonry

1 A brick wall may be constructed as thin as 10 cm. But in case of a stone wall, the

thickness of the wall is usually not less than 38 cm.



2 Bricks are easily affected by chemical reactions due to present in salts in urine

or sewage, but the stone masonry is not affected by such reaction.

Ans. 6 Merits and Demerits of Flemish Bond-

• It provides better appearance.

• It can be made more economical by using cheap quality of bricks on the

back of the wall.

• It weakens the overall strength of the wall because of maximum use of brick

bats and existence of continuous vertical joints.

• It cannot be providing in walls having thickness less than one and half brick.

Ans. 7 Difference between Arches and Lintels-

An arch is a mechanical alignment of wedge-shaped blocks of bricks or stones

together supporting each other and successively supporting at the ends by piers or

abutments.

A lintel is a horizontal structural segment installed to span openings for doors,

windows and corridors.

Ans. 8 Causes of Dampness-

1. Rain penetration

2. Level of site

3. Drain ability of soil

4. Climate condition

5. Defective orientation of building

6. Moisture entrapped during construction

7. Defective construction e.g. joints

8. Use of poor quality bricks which ultimately absorb a lot of water.

9. Use of Poor quality of concrete (permeable concrete)



Ans. 9 Load bearing structure-

A load bearing wall transfers the loads form slabs above it to the foundation. These

walls can be made of concrete, masonry or block materials. Most of the exterior

walls of a building structure are considered as load bearing.

Ans. 10 Light Weight Concrete Blocks-

Lightweight concrete is utilized as thermal insulation in the form of bricks

and blocks over flat roofs or non-loading walls. Bulk filling by applying

relatively low strength material for old sewer pipes, wells, unused cellars and

basements, storage tanks, tunnels and subways.

PART B

Ans 1. Various laboratory test on test on Stone-

1. Acid Test: Acid test is used to investigate how much atmospheric action can

be resisted by stone. In this test 100 grams of stones in chipped form are

kept in a 5% solution of hydrochloric acid or sulphuric acid. After 3 days

stones in chipped form are taken out and dried. If the edges of stones are

sharp as earlier, it indicates that stone can resist weathering actions.

2. Crushing Strength: Crushing test is used to investigate the compressive

strength of stone. In this test stone is cut into cubes of dimension 40mm.

Sides of cube are finely dressed and finished. Cubes of stones are then kept

in water for 72 hours. Then 5mm thick layer of plywood or plaster of paris is

applied on the load bearing surface. Load is applied axially on load bearing

surface using universal testing machine or crushing testing machine until

cracks appear on the stone or stone starts crushing. Crushing strength of the

stone is the maximum load at which it crushes divided by the area of the

load bearing surface.

3. Impact Test: This test is carried out to determine the toughness of stone.

This test requires an 'Impact Testing Machine'. In this test stones are filled in



test cylinder of diameter 25 mm and height 25 mm. The cylinder is placed

on machine and steel hammer of weight 20 N is allowed to fall on the

specimen in cylinder. The height of first fall is 1 cm, height of second fall is

2 cm and so on. The height at which specimen breaks is recorded. If

specimen breaks at 'n cm' then 'n' is the toughness index of stone.

4. Microscopic Test: In this test specimen of stones is placed under

microscope and various properties are studied such as grain

size, texture of stone, pores, veins, shakes etc.

Ans. 2. Role of flyash in manufacturing of Bricks and Cement-

• Fly ash brick (FAB) is a building material, specifically masonry units,

containing class C or class F fly ash and water. Compressed at 28 MPa (272

atm) and cured for 24 hours in a 66 °C steam bath, then toughened with an

air entrainment agent, the bricks last for more than 100 freeze-thaw cycles.

Owing to the high concentration of calcium oxide in class C fly ash, the

brick is described as "self-cementing". The manufacturing method saves

energy, reduces mercury pollution, and costs 20% less than traditional clay

brick manufacturing.

• Advantages

1. It reduces dead load on structures due to light weight (2.6 kg, dimension:

230 mm X 110 mm X 70 mm

2. Same number of bricks will cover more area than clay bricks

3. High fire Insulation

4. Due to high strength, practically no breakage during transport and use.

5. Due to uniform size of bricks mortar required for joints and plaster reduces

almost by 50

6. Due to lower water penetration seepage of water through bricks is

considerably reduced.

https://en.wikipedia.org/wiki/Building_material

https://en.wikipedia.org/wiki/Masonry

https://en.wikipedia.org/wiki/Fly_ash

https://en.wikipedia.org/wiki/Calcium_oxide

https://en.wikipedia.org/wiki/Mercury_pollution

https://en.wikipedia.org/wiki/Transport

https://en.wikipedia.org/wiki/Mortar_(masonry)

https://en.wikipedia.org/wiki/Seepage



• The use of fly ash in Portland cement concrete (PCC) has many benefits

and improves concrete performance in both the fresh and hardened state. Fly

ash use in concrete improves the workability of plastic concrete, and the

strength and durability of hardened concrete. Fly ash use is also cost

effective. When fly ash is added to concrete, the amount of Portland cement

may be reduced.

• Benefits to Fresh Concrete. Generally, fly ash benefits fresh concrete by

reducing the mixing water requirement and improving the paste flow

behavior.

Ans. 3 Different method of Seasoning of Timber-

The wood spice process is the process by which the moisture in the wood is

reduced to the required level.

By reducing the moisture content, strength, elasticity, and durability properties are

developed. A well-seasoned wood contains 15% moisture content.

It is a process by which the amount of moisture in a freshly cut tree is reduced to a

suitable level. Doing this increases the durability of the wood. The different

methods of spice used can be classified into:

Natural Seasoning- It can be air seasoning or water seasoning. Air seasoning is

done in the shed with a platform. As shown in below fig, wooden piles are stacked

on platforms approximately 300 mm high.

Care is taken to see that there is proper air circulation around each wooden hair.

Over a period, the moisture content decreases in a natural process.

A well-seasoned wood contains only 15% moisture. It is slow but has a good

seasoning process. Water is sprayed on the banks of rivers. The thick end of the

wood is placed, pointing upwards. After a period of 2 to 4 weeks, the wood is

taken out. During this period, the sap contained in the wood is largely washed

away. The wood is then stalked in a shed with free air circulation.

https://civiljungle.com/difference-between-timber-and-wood/



Artificial Seasoning: In this method, the wood is kept in a chamber with

regulated heat, Controlled humidity and proper air circulation. Seasoning can only

be completed in 4 to 5 days.

There Are Different Ways of Seasoning:

• Boiling Seasoning:

• Kiln Masala Seasoning

• Chemical Seasoning

• Electrical Seasoning

Ans. 4 Causes of failure and remedial measures of foundation

• Unequal settlement of the sub-soil

• Unequal settlement of the masonry

• Withdrawal of moisture from the sub- soil

• Lateral pressure on the superstructures

• Horizontal movement of the earth

• Transpiration of trees and shrubs

• Atmospheric action.

Unequal Settlement of the Sub-soil

This occurs due to various reasons such as unequal distribution of load on the

foundation, varying bearing power of the sub-soil, eccentricity of the loaded.

Due to unequal settlement of the sub-soil, cracks are formed in the buildings,

which in future, leads to serious defects. Following are the measures to be

adapted to prevent such failure:



• Foundation should rest on rock or hard moorum.

• Design of foundation should be appropriate to the nature of sub-soil.

• It should be seen that the allowable bearing pressure on the soil is not

exceeded, even under the worst conditions

Unequal Settlement of the Masonry

Mortar joints may shrink and compress which may lead to unequal settlement of

the masonry. Measures to avoid such situations are as follows:

• Mortar to be used in the masonry should be stiff and in line with the

workability desired.

• The masonry work should be raised evenly.

• The height of wall to be raised per day should be limited to one metre, if

lime mortar is used and to 1 -50 metres, if cement mortar is used.

• Proper watering should be done to the masonry work.

Withdrawal of Moisture from the Sub- soil

This occurs at places where there is considerable variation in the height of water

table. When water table falls, the soil particles lose cohesion and hence, there is

shrinkage of soil, resulting in the cracks to the buildings. The precaution to be

taken to avoid such failure would be to drive piles unto the hard rock.

Lateral Pressure on the Superstructure

The thrust of a pitched roof or arch or wind action on the superstructure causes

wall to overturn. Remedial measures to prevent this failure would be to provide a

sufficient wide base and to design the foundations for the worst conditions.

Horizontal Movement of the Earth

Very soft soil is liable to give way under the action of load especially at places

such as sloping ground, river banks, etc. hence, in such cases, it is desirable to

construct retaining walls or to drive sheet piles to prevent the escape of the earth.



Transpiration of Trees and Shrubs

The roots of trees planted near a building may extend up to the foundation level

and may absorb the moisture. This effect is seen in the form of a depression on the

ground and it may lead to cracks in the building. Remedial measures are as

follows:

• Foundations should be taken sufficiently deep. A minimum depth of one

meter is required for this purpose.

• Fast growing and water seeking trees should not be planted near the building

with a minimum distance of 8 meters.

Atmospheric Action

Rain and sun are the main atmospheric agents to seriously affect the foundations of

a building. Heavy rains or considerable variation in temperature or frost action may

damage the foundations. Rain water may create pockets near the walls and while

descending, it may carry certain chemicals and salts obtained from sewage, animal

dung, etc. These chemicals and salts may react with the materials used for the

foundation work and turn them into powder. Remedial measures to be taken are as

follows:

• Foundation should be taken beyond the depth up to which rain water can

reach.Ingress of rain water and harms associated with it can therefore be

avoided.

• Suitable underground drains should be provided to maintain the water table

at a definite level.

Ans 5. Various construction features of Shell Roof-

Shell roof is basically the modification of a pitched roof and covers large areas of

the building. Moreover, shell roof is three-dimensional structures consisting of thin

membrane slabs, curved in one or more directions which transfer the loads on

points of support, i.e. columns, beams, walls etc. Shell roofs are built with several

materials such as in situ reinforced concrete, timber, steel sheets, ceramics, glass,

plastics, hard board, lattice and composite structure etc.

https://gharpedia.com/pitched-roof/



Shell roofs are used for covering large span structures with a single storey, e.g

assembly halls, recreation centers, theatres, factories, research labs etc. A shell roof

is commonly used in public building because shell roof is aesthetically pleasing.

When the inside of the building is required to be open without any walls or pillars

then the shell roof is very useful than flat or even pitched roof. The shells roofs are

lighter in weight and save reinforcing steel and concrete.

Fig. Shell Roof

Singly-curved shell and doubly-curved shell are the types of shell roofs. The

thickness of singly-curved shells should not be less than 5 cm. Double curved

shells are structurally more efficient than single curved shells. However,

preparation of the centring work of doubly-curved shell roof is more difficult. Shell

units are effectively used for replacing solid slabs

Ans. 6 Types and Method of Shoring and Underpining

Types of Shoring- Shoring is lateral support for an unsafe structure that is

constructed for temporary support. These support a wall laterally. Shorings

are used under the following conditions:

• When a wall shows signs of bulging out due to bad workmanship.

https://en.wikipedia.org/wiki/Wall



• When we have to repair a crack on the wall due to unequal settlement of

foundation.

• When an adjacent structure is to be dismantled.

• When openings are to be made or enlarged in the wall.

Types of Shoring

Shores may be of the following types:

1. Raking Shores

2. Flying Shores

3. Dead Shores

1. Raking Shores

In this method, inclined members, called rakers are used to give lateral support to

the wall.A raking shore consists of the following

Rakers or inclined members,

• Wall plate,

• Needles,

• Cleats,

• Bracing, and

• Sole plate.

2. Flying or Horizontal Shores

Flying shores are a support system which provides horizontal support to two

parallel party walls when removal or collapse of the intermediate building takes

place.

All types of shoring system of supporting the unsafe structure in which the shores

do not reach the ground are the flying shores. If the walls are quite near to each

other (distance up to 9 m), single flying shore



3.Dead or Vertical Shores

Dead shore is a shoring system in which a dead shore in the form of vertical

member support horizontal needles which transfer the load of the wall, roofs and

floors etc.

The needles transfer the load of the wall etc., to the dead shores.

This type of shoring is use for the following purposes:

• To rebuild the defective lower part of the wall.

• To rebuild or deepen the existing foundation.

• To make large opening in the existing wall at lower level for underpinning and

such type of work.

Underpinning - Underpinning is a method used for increasing the depth of any

foundation. In traditionally built homes, height of the basement is insufficient.

Underpinning comes to the rescue as it helps you to get a deeper area.

Methods for Underpinning

1. Mass Pouring

The most commonly and traditionally used method of underpinning is mass

pouring. It is suited for shallow underpinning in which a lot of digging is not

required. It simply involves excavating the weak soil underneath the surface and

pouring concrete in its place to strengthen the base. Since concrete is stronger than

soil, the weight of the entire structure is carried effectively by the concrete.

Following are the advantages of using the mass pouring method:

1. Low cost of labor

2. The simplicity of engineering



3. The continuity of the building’s use during construction without involving any

need of evacuating the property

2. Beam and Base Method

Another method of underpinning involves the use of beam and base. The method

also makes use of traditional mass concrete base, and incorporates beams to support

the existing foundation. The load is transferred to a concrete beam that is

constructed below, above or in place of the existing foundation. The beam then

transfers the load to a mass concrete base that is spread evenly for support. The

construction of the beams depends on the architecture of the structure built on the

foundation and the type of load applied to the foundation.

3. Pile Method

If you opt for the pile method, the general contractor drives piles at equal

distances along both sides of the wall. The piles are connected by concrete or steel

needles that penetrate through the walls. It is the most effective method for houses

built in clay soil as well as properties constructed in waterlogged areas. The pile

method helps in relieving the load of the existing foundation.

Ans. 7 Paints – their types and application

In general, paints can be divided depending on their properties and application:

a) Emulsion paints, also known as dispersion paints. They can be divided

depending on the type of adhesive used:

https://www.pourconcrete.ca/



● Acrylic paints – their binder is water dispersion of acrylic resin. They are

characterized by very good flexibility and adhesion to the substrate. Acrylic paints

have a wide range of applications and can be used to cover, for example, wood,

concrete, plastics, plasters and many other surfaces. They have high abrasion

resistance and allow water vapor, however, the surfaces painted are susceptible to

various types of damage,

● Latex paints – the binder of this type of paint is rubber. Latex paints are

extremely resistant to moisture and cleaning. Their advantage is a very easy

application on various surfaces. The disadvantage is usually the high price. An

example of the most modern latex paints are ceramic paints. They contain ceramic

particles that form the so-called stain resistant coating. Thanks to this, the walls

painted with them do not absorb dirt and dust,

● Acrylic-latex paints – have the characteristics of acrylic paints, i.e. good air

permeability and scrub resistance, and flexibility of latex paints,

● Vinyl paints – the binder of these paints is polyvinyl acetate or polyvinyl

chloride. They are used mainly in utility rooms, and their greatest advantage is

easy washability. Unfortunately, they also make it difficult for the walls to breathe

due to the low vapor permeability.

b) Lime paint – the binder of these paints is lime putty diluted with water. They

are cheap, but not durable. In order to increase the durability, admixtures of other

water-borne adhesives (e.g. glue) or the addition of polyvinyl acetate are used.

Lime paints are used for painting fresh concrete substrates, lime plasters and walls

previously painted with lime paints. Currently, the use of these paints is very rare.

This is due to their very low durability, dustiness and tendency to create cracks,

c) Distempers – these are durable and breathable paints with excellent solubility in

water. Plant or animal glues are their binder. Distempers are not very resistant to

dirt, they cannot be washed and they absorb moisture from the environment. They

are mainly suitable for painting lime and cement-lime plasters. Distempers are

practically no longer used because they have been replaced by more modern paints,



d) Silicate paints – their binder is potassium water glass. These paints are durable,

non-flammable, resistant to moisture and have high mechanical resistance. They

can be applied on brick, concrete and wooden substrates. When drying, they cure

under the influence of CO2 contained in the air,

e) Silicone paints – create a durable and weather-resistant coating. They are

produced based on a silicone resin. They are suitable for painting concrete,

wooden, brick and plaster substrates. These paints have the ability to self-clean,

f) Epoxy paints – these are two-component paints, consisting of an epoxy resin

and a hardener. Before applying, both components are mixed together. Epoxy

paints show high resistance to mechanical damage and chemicals. They are used,

for example, for painting concrete floors. For their production, additives based on

phosphate esters from the Roflam series (F5, B7, P) can be used.

Types of Varnishes

1. Solvent-based varnishes

Solvent-based varnishes form very hard coatings that show high resistance to

mechanical damage. By creating a homogeneous structure, they also prevent the

penetration of moisture. The most important component of this type of varnish is

the solvent, which is usually characterized by an unpleasant and intense smell.

Solvent-based varnishes can be divided into a number of subgroups:

a) Solvent-based polyurethane varnishes – they are one of the best varnishes

available on the market. There are one- and two-component varnishes. One-

component polyurethane varnishes use the moisture contained in the air to harden.

In contrast, the characteristic feature of varnishes based on two components are

two stages of drying. During the first stage, the solvent evaporates, then the

chemical drying takes place and the varnish is hardened. The advantages of

polyurethane varnishes are their resistance to moisture, as well as high flexibility.

Unfortunately, they are usually very toxic.

b) Nitrocellulose lacquers – the main raw material for their production is

nitrocellulose resin. It is usually obtained from cotton, which is treated with

https://www.products.pcc.eu/en/products/markets-and-applications/paints-coatings/function/flame-retardants/



sulfuric or nitric acid. The nitrocellulose varnishes also contain a number of other

substances, such as polyester and alkyd resins, which improve their hardness and

gloss. Plastifying additives are also used, most often phthalates, which increase

resistance to light and temperature. Nitrocellulose varnishes are used as materials

for painting furniture and various wooden elements.

2. Water-borne varnishes can be divided into three groups based on the type

of adhesive used:

a) Acrylic varnishes – these are cheap substances that create transparent coatings,

without changing the colour of the wood. They are characterized by low

abrasiveness and mechanical resistance and their biggest advantage is low toxicity.

They are mainly used for painting wooden household products and painting floors

in places with low traffic,

b) Water-based polyurethane varnishes – they show very high resistance to

abrasion and mechanical damage. In addition, they are insensitive to moisture and

temperature changes. Like polyurethane solvent-based varnishes, they are divided

into one- and two-component varnishes. Due to the creation of very durable

coatings, they are often used on floors in living rooms,

c) Polyurethane-acrylic varnishes – their properties depend on the proportion of

both components. Varnishes containing more polyurethane in composition are

characterized by higher hardness. Polyurethane-acrylic varnishes exist in one or

two-component form. They can also contain a number of hardeners that improve

their mechanical strength and abrasion resistance. Unfortunately, it also increases

their toxicity.

PART C

Q. 1 Standard test performed on Bricks

The following laboratory tests may be conducted on the bricks to find their

suitability:



(i) Crushing strength

(ii) Absorption

(iii) Shape and size and

(iv) Efflorescence.

(i) Crushing Strength: The brick specimen are immersed in water for 24 hours.

The frog of the brick is filled flush with 1:3 cement mortar and the specimen is

stored in damp jute bag for 24 hours and then immersed in clean water for 24

hours. The specimen is placed in compression testing machine with 6 mm plywood

on top and bottom of it to get uniform load on the specimen. Then load is

applied axially at a uniform rate of 14 N/mm2. The crushing load is noted. Then the

crushing strength is the ratio of crushing load to the area of brick loaded. Average

of five specimen is taken as the crushing strength.

(ii) Absorption Test: Brick specimen are weighed dry. Then they are immersed in

water for a period of 24 hours. The specimen are taken out and wiped with cloth.

The weight of each specimen in wet condition is determined. The difference in

weight indicate the water absorbed. Then the percentage absorption is the ratio of

water absorbed to dry weight multiplied by 100. The average of five specimen is

taken. This value should not exceed 20 per cent. Sharp edges. To check it, 20

bricks are selected at random and they are stacked along the length, along the

width and then along the height. For the standard bricks of size 190 mm × 90 mm

× 90 mm. IS code permits the following limits:

Lengthwise: 3680 to 3920 mm

Width wise: 1740 to 1860 mm

Height wise: 1740 to 1860 mm.



The following field tests help in ascertaining the good quality bricks:

Uniformity in size

Uniformity in Colour

Structure

Hardness Test

Sound Test

Strength Test.

(i) Uniformity in Size: A good brick should have rectangular plane surface

and uniform in size. This check is made in the field by observation.

(ii) Uniformity in Colour: A good brick will be having uniform colour

throughout. This observation may be made before purchasing the brick.

(iii) Structure: A few bricks may be broken in the field and their cross-

section observed. The section should be homogeneous, compact and free

from defects such as holes and lumps.

(iv) Sound Test: If two bricks are struck with each other they should produce

clear ringing sound. The sound should not be dull.

(v) Hardness Test: For this a simple field test is scratch the brick with nail.

If no impression is marked on the surface, the brick is sufficiently hard

(vi) Efflorescence: The presence of alkalis in brick is not desirable because

they form patches of grey powder by absorbing moisture. Hence to

determine the presence of alkalis this test is performed as explained

below: Place the brick specimen in a glass dish containing water to a

depth of 25 mm in a well-ventilated room. After all the water is absorbed

or evaporated again add water for a depth of 25 mm. After second

evaporation observe the bricks for white/grey patches. The observation is

reported as ‘nil’, ‘slight’, ‘moderate’, ‘heavy’ or serious to mean



(a) Nil: No patches

(b) Slight: 10% of area covered with deposits

(c) Moderate: 10 to 50% area covered with deposit but unaccompanied

by flaking of the surface.

(d) Heavy: More than 50 per cent area covered with deposits but

unaccompanied by flaking of the surface.

(e) Serious: Heavy deposits of salt accompanied by flaking of the surface.

Ans. 2 Mortar- Mortar is a workable paste which dries to bind building blocks

such as stones, bricks, and concrete masonry units, to fill and seal the irregular

gaps between them, and sometimes to add decorative colors or patterns to masonry

walls.

Lime Mortar- Lime mortar is a traditional building material, and is now only

normally used for restoration, and repair of old buildings. It was generally made

with a mix ratio of about 1:3 (lime: sand), and sets by carbonation. Pozzolans such

as volcanic ash or ground clay bricks, and tiles were often added to give a higher

strength.

Cement Lime mortar may be made at ratios of 1:0.25:3 (cement: lime: sand) for

higher strength and durability down to 1:3:12 for a weaker mix capable of

accommodating more movement. Cement lime mortar should not normally be used

below the damp proof course (dpc).

Role of Sand in Mortar-Sand offers the requisite surface area for the film of

cementing materials to adhere and to spread. Sand helps to prevent mortar

shrinkage. It also prevents cracking of mortar during setting. Well-graded sand

increases the density of mortar.

Ans.3 Stone masonry has been in use in many places from ancient times. Where

stones are easily available, random rubble work will be cheaper than plastered

brickwork.

https://www.sciencedirect.com/topics/engineering/carbonation

https://www.sciencedirect.com/topics/engineering/pozzolans

https://civilseek.com/types-classification-of-bricks/



Where the groundwater level is high, and bricks are liable to deteriorate, random

rubber work is preferred even today for foundation work.

The sizes of stones used in stone masonry work depend on the type of masonry.

The stones should not be larger than what can be handled and placed by one

person.

Types of Stone Masonry- There are two main types of stone masonry-

Rubble Masonry

In this type of masonry irregular shapes and sizes of stones are used. They

may be hammered to remove sharp edges, and various types are present.

Dry rubble masonry:

In this type, walls are built in courses, but without mortar and this type of masonry

is extensively used for the construction of compound walls. It is the cheapest type

of construction, but it needs skilled masons for its process.

Random rubble masonry:

In this type, quarry-dressed stones of various shapes and sizes are used, and it may

be coursed or uncoursed rubble masonry.

Coursed rubble masonry: In this, the wall is built in courses varying from 300-

450 mm and all the courses need not be of the same height.

Uncoursed rubble masonry: It is the cheapest stone masonry of all the types.



Square rubble masonry:

It may be coursed or uncoursed, and the courses may be of equal or unequal

heights. In this type, stones have straight bed and sides and are given straight cut

finishes or faces are hammer-dressed.

Polygonal walling:

In this case, hammer-finished stones are arranged to give polygonal shapes on the

face, and these types of works can be carried out by skilled masons only.

Flint walling:

In this type of construction, the masonry may be coursed or uncoursed. In flint

walling, flints of varying thickness from 50-75 mm, length 150-300 mm are

preferred, and stones are extremely hard but brittle. The strength of the wall may

be increased by providing tacking courses of tiles or bricks.

Ashlar Masonry:

Ashlar masonry consists of prepared stonework, i.e. stones are cut neatly in either

square or rectangular shape of height 250-300 mm. All the stones in a course have

the same height and length of the stone should not be more than three times the

height, and it should not be less than half the height. There are different types in

ashlar masonry, and they are

Ashlar fine tooled:

In this type, blocks are chisel dressed on all the faces, and they are built in regular

courses of not less than 300 mm and the mortar joints should not exceed 3 mm.

This is the finest of stone masonry and also the costliest of all.



Ashlar rough tooled:

In this type, the bed and sides are finely chiseled but only on the facing sides, and

the inside facing remains roughly dressed. The thickness of mortar joints may be of

6 mm.

Ashlar chamfered:

In this type, the interior remains quarry finished only and in facing the strip around

the periphery is chamfered at an angle of 45 degrees. Then another strip of 12 mm

width is provided and if the projections are more than 80 mm, they are removed by

hammering.

Ashlar rock or quarry-faced:

In this case, blocks have straight bases and edges, on the facing side a strip of 25

mm is chisel finished along the perimeter. The interior remains quarry finished

only, and the thickness of the mortar joints may be of 10 mm.

Ashlar facing:

In this type, the main wall is made of brick or rubble masonry or from concrete.

The joints of the stones are dressed perfectly and facing blocks are not less than

200 mm in height, the width is 1.5 times the height.

Ashlar block in course:

This type of masonry is in between rubble and ashlar masonry. The faces are

hammer-dressed only, and the vertical joints are not as straight and fine has in

ashlar masonry. This type of masonry is adopted in heavy works like retaining

walls, piers of bridges, etc.



Merits of Stone Masonry Construction

These general advantages apply for all types of masonry units (brick, stone or

concrete blocks):

• Masonry is non-combustible, so improves fire protection for the building

and its occupants. Fireplaces are commonly made of masonry for the same

reason.

• Masonry offers a high resistance against rotting, pests, weather, and natural

disasters such as hurricanes and tornadoes.

• Masonry structures provide an attractive rustic or elegant look for a home or

building, depending on the material used and the workers’ expertise.

• Being durable and resistant, masonry can withstand large amounts of

compressive weight loads.

• Masonry units increase the thermal mass of a building.

• Masonry buildings have longer lifespans than any other building type.

Demerits of Masonry Construction

• Masonry construction involves heavy materials such as bricks, stone and

concrete blocks. These cannot be transported in conventional vehicles, and

in some cases they must be ordered from special catalogs, especially stones.

• The stability of masonry structures depends completely on their foundation.

If any settling of the foundation occurs, cracks are likely and they must be

repaired to prevent moisture infiltration and damage.

• Masonry activities cannot be done during heavy rain or freezing conditions,

since mortar will be severely affected.

• Masonry construction requires a good amount of time and adequate project

planning. Depending on the type or masonry, specialized manpower may be

necessary.

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Ans 4. Requirement of Good Staircase

Requirements of Good Stairs

A good stair should provide an easy, quick and safe mode of communication

between the various floors of the building. General requirements of good stairs are

as mentioned below.

1. Location

It should preferably be located centrally, ensuring sufficient light and ventilation.

2. Width of Stair

The width of stairs for public buildings should be 1.8 m and for residential

buildings 0.9 m.

3. Length

The flight of the stairs should be restricted to a maximum of 12 and minimum of 3

steps.

4. Pitch of Stair

The pitch of long stairs should be made flatter by introducing landing. The slope

should not exceed 400 and should not be less than 250.

5. Head Room

The distance between the tread and soffit of the flight immediately above it, should

not be less than 2.1 to 2.3 m. This much of height is maintained so that a tall

person can use the stairs with some luggage on its head.



6. Materials

Stairs should be constructed using fire resisting materials. Materials also should

have sufficient strength to resist any impact.

7. Balustrade

All open well stairs should be provided with balustrades, to avoid accidents. In

case of wide stairs it should be provided with hand rails on both sides.

8. Landing

The width of the landing should not be less than the width of the stair.

9. Winders

These should be avoided and if found necessary, may be provided at lower end of

the flight.

10. Step Proportions

The ratio of the going and the rise of a step should be well proportioned to ensure a

comfortable access to the stair way.

Construction detail of Staircase-

The basic components of a staircase are the tread, the horizontal surface we walk

on; the riser, the vertical part between each tread; and the stringer, a structural

support that holds the treads in place and provides stability. What we call a step is

actually a combination of a tread and a riser, or one step up or down from our

previous position. In some cases, such as open stairs, the riser is missing and we

can see through the stairs.



Fig.Diagram of a staircase

Other optional parts of a staircase include the nosing, banister, and balusters.

Nosing is a small part of a tread that overhangs the riser. The banister, which is

also called a railing or a handrail, is both a decorative and a safety feature that

prevents people from falling off the side of a staircase or allows them to hold on

for stability. Some handrails are attached directly to a wall while others are

positioned on the open part of the staircase. When they are on the open part, the

banister is held up by balusters, or vertical supports attached to a tread at the

bottom and the banister at the top.

There are also different types of steps, determined by the shape of tread. The basic

step involves a rectangular tread. The most common variation of a simple step is a

winder. These involve treads that are wider on one side than the other. This helps

change the direction of a staircase gradually. Sometimes to break up a long,



straight staircase or to provide a space to turn when the steps change direction, a

wide platform step called a landing is used. In some staircases, designers include

an elegant feature called a bullnose step. This is when the first step off the ground

floor is wider than the rest of the steps.

Suitability of different types of stairs-

Straight flight stairs.

It is the simplest type of stairs, and consists of one or in some cases two flights

running in one direction only. These stairs are used, when the space available is

narrow and long.

Dog legged stairs.

It is a very common and popular type of stairs and is used in public as well as

residential buildings. It consists of two flights running in opposite directions,

separated by a half space landing or a quarter space landing and a set of winders.

The dog-legged stair is so called because the bent of the stairs is similar to the

dog’s leg. When the space available is equal to twice the width of the stairs, dog

legged stair is used.

Open newel stairs.

It is similar to the dog legged, stair except that in this case the two flights are

separated by an open well. The open newel stair is a convenient type of stair and is

generally used in public buildings. The width of the open well depends upon the

space available but the varies from 60 cm to 120 cm. The two flights ate either

separated by a half space lending’ or two quarter space landings with a set of steps



Quarter turn stairs.

In this type of stair, the two flights run at right angles to each other and are

separated by a quarter space larding. The stairs are generally provided when wall

support is on one side only, or when in a huge apartment such as an entrance hall,

stairs are to be provided.

Bifurcated stairs.

These stairs are commonly used in public buildings. In this type of stairs, the

bottom flight is wider and is bifurcated into two narrower flights at the landing.

The bifurcated stairs may be of two types, viz. Quarter turn and half turn. In the

quarter turn type, the upper the lower flights run at right angle whereas in the half

turn bifurcated stairs, the sets of flights go in opposite directions as in a quarter

turn stair and dog-legged stair respectively.

Geometrical stairs.

The geometrical stairs are generally used in high class residential buildings. The

stair is in the form of some curve, having all the steps as winders, radiating from

the-centre of curvature of the curve. The hand rail of a geometrical stair, continues

without interruption and without any angular turn-Considerable skill is required for

fie designing and construction of a geometrical stair. The minimum width of this

stair has been, fixed at 1.75 m.

Spiral stairs.

These stairs are generally constructed either of cast iron or R.C.C. The steps which

are all winders, radiate from a central vertical shaft and are attached to it. The steps

are generally pre-cast and are fitted to the central pillar. These stairs are used on

the back-side of a building for emergency use as well as in those places where the

space is limited.



Ans. 5 (a) Flat slab and their application-A Flat Slab can also be refers to as

Beamless Slab, It is a reinforced concrete slab supported directly by concrete

columns without the use of beams. A plain ceiling is obtained thus giving attractive

appearance from an architectural point of view.

Flat slab is defined as one sided or two-sided support system with sheer load of the

slab being concentrated on the supporting columns and a square slab called ‘drop

panels’. The Drop panels play a significant role here as they augment the overall

capacity and sturdiness of the flooring system beneath the vertical loads thereby

boosting cost effectiveness of the construction. Usually the height of drop panels is

about two times the height of slab.

(b) Method and Material for Damp proofing-

1. Membrane damp proofing

In this method of damp proofing a water repellent membrane or damp proof

course(D.P.C.) is introduced in between the source of dampness and the part

of building adjacent to it. Damp proofing course may consist of flexible

materials such as bitumen, mastic asphalt, bituminous felts, plastic or

polythene sheets, metal sheets, cement concrete. Damp proofing course may

be provided either horizontally or vertically in floors, walls etc.

2. Integral damp proofing

In the integral damp proofing method certain water proofing compounds are

added to the concrete mix, so that it becomes impermeable. The common

water proofing compounds may be in the following three forms.

i. Compounds made from chalk, talc, fullers earth, which may fill the

voids of concrete under the mechanical action principle.

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ii. Compounds like alkaline silicates, aluminum sulphate, calcium

chlorides, etc. which react chemically with concrete to produce water

proof concrete.

iii. Compounds like soap, petroleum, oils, fatty acid compounds such as

stearates of calcium, sodium, ammonia etc. work on water repulsion

principle. When these are mixed with concrete, the concrete becomes

water repellent.

3. Surface treatment

Moisture finds its way through the pores of material used in finishing. In

order to check the entry of the moisture into the pores, they must be filled

up. In the surface treatment method a layer of water repellent substances or

compounds are applied on these surfaces through which moisture enters. The

use of water repellent metallic soaps such as calcium and aluminumoletes

and stearates are much effective against rain water penetration. Pointing and

plastering of the exposed surfaces must be done carefully, using water

proofing agents like sodium or potassium silicates, aluminum or zinc

sulphates, barium hydroxide and magnesium sulphates etc. Surface

treatment is effective only when the moisture is superficial and is not under

pressure. Sometimes, exposed stone or brick wall face may be sprayed with

water repellent solutions. The walls plastered with cement, lime and sand

mixed in proportions of 1:1:6 is found to serve the purpose of preventing

dampness in wall due to rain effectively.

4. Cavity wall construction

Cavity wall construction is an effective method of damp prevention. In this

method the main wall of a building is shielded by an outer skin wall, leaving

a cavity between the two. The cavity prevents the moisture from travelling

from the outer to the inner wall.













5. Guniting

In this method of damp proofing, an impervious layer of rich cementmortar

is deposited under pressure over the exposed surfaces for water proofing or

over pipes, cisterns etc. for resisting the water pressure. The operation is

carried out by use of a machine known as cement gun. The cement gun

consists of a machine having arrangements for mixing materials and a

compressor for forcing the mixture under pressure through a 50 mm dia

flexible hose pipe. The hose pipe has nozzle at its free end to which water is

supplied under pressure through a separate connection. The surface to be

treated is first thoroughly cleaned of dirt, dust, grease or loose particles and

wetted properly. Cementmortar consists of 1: 3 cement sand mix, is shot on

the cleaned surface with the help of a cement gun, under a pressure of 2 to 3

kg/cm2. The nozzle of the machine is kept at a distance about 75 to 90 cm

from the surface to be gunited. The mortar mix of desired consistency and

thickness can be deposited to get an impervious layer. The layer should be

properly cured at least for 10 days. Since the material is applied under

pressure,it ensures dense compaction and better adhesion of the rich

cementmortar and hence the treated surface becomes water proof.

6. Pressure grouting

This consists of forcing cement grout under pressure, into cracks, voids,

fissures and so on present in the structural components of the building, or in

the ground. Thus the structural components and the foundations which are

liable to moisture penetration are consolidated and are thus made water-

penetration-resistant. This method is quite effective in checking the seepage

of raised ground water through foundations and sub-structure of a building.





















(c) Purpose and use of Partition Wall-

The essential purpose of partition walls is to divide buildings into suitably sized

rooms, halls, etc. but they may also be required to support floor and ceiling joists.

They can thus be described as loadbearing or non-loadbearing, and this factor may

decide the type and thickness of the materials used for construction. For example,

non-loadbearing walls may be erected using aerated concrete blocks only 60 mm

thick, depending on the length and height whereas, if loads are to to superimposed,

the minimum thickness for this type of block is 75 mm.

Purpose of Partition walls:

• These walls are made to divide the floor area of the building.

• For privacy purposes for the inhabitants of the building

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