2. KTU SYLLABUS
BUILDING MATERIALS
BRICKS - PROPERTIES AND SPECIFICATION
CEMENT BLOCKS – PROPERTIES AND SPECIFICATION
Cement
OPC, properties, grades; other types of cement and its uses (in brief).
3. 1. Brick
One of the oldest building material.
Extensive usage because of its strength, durability, reliability and low cost.
Made from soil and hence the properties of bricks depends on properties of soil.
Preparation:-
Brick earth is first moulded to the desired shape (mostly rectangular) of uniform size
and then moulded bricks are dried and burnt in brick kilns.
Constituents of good brick earth:-
Mixture of clay and sand ( i.e. alumina and silica) in such proportions so as to render
plastic state when mixed with water.
4. Composition of Good Brick Earth
S.No Constituent Percentage Function
1. Alumina 20 - 30
•Present in clay;
•Imparts plasticity to earth so that it can be moulded.
•Excess alumina causes shrinkage and warping during drying and
burning.
2. Silica 50 - 60 •Prevents cracking, shrinking and warping of raw bricks.
•Imparts uniform shape to the bricks.
•Excess silica makes the bricks brittle.
3. Lime < 5 •Prevents shrinking of bricks.
• Excess of lime causes the bricks to melt and, hence, to lose its
shape.
4. Oxide of Iron 5 - 6
•Imparts red colour.
• Excess of iron oxide makes the colour dark blue or blackish.
• Less quantity results in yellowish colour.
•Helps to fuse the sand thereby increases the hardness of bricks.
5. Magnesia < 2 •Imparts yellow colour and decreases shrinkage.
• Excess magnesia leads to decay of bricks.
5. Size and Weight
Standard size recommended by BIS is 19cm*9cm*9cm
Size of brick including mortar thickness – 20cm*10cm*10cm (Nominal size of brick)
Test carried out for inspecting the size
20 bricks of standard size are stacked length wise, along the width and along the height.
For good quality bricks,
Weight of 1 m³ of brick earth is 18 kN.
Average wt. of 1 brick will be around 30 – 35 N (3 – 3.5 kg).
Length 368 – 392 cm
Width 174 – 186 cm
Height 174 – 186 cm
6. Manufacture of bricks
Four process involved in manufacture are
1. Preparation of brick earth
2. Moulding of bricks
3. Drying of bricks
4.Burning of bricks
7. 1. Preparation of brick earth
A) Removal of loose soil
Top layer of soil about 30 cm contains lot of impurities and organic matters etc are removed
B) Digging spreading and cleaning
Earth is then dug out from the ground and spread in to heap about 50cm to 150 cm height
Entire un desirable matters like stones , vegetable matters etc are removed.
C)Weathering
Earth is then exposed to atmosphere for softening for few weeks
D)Blending and tempering
Clay is then mixed with suitable ingredients and required quantity of water is added to clay
and the whole mass is kneaded under the feet of men or cattle to make brick homogeneous
8. b) MOULDING
Gives shape to brick is called moulding
A) Hand moulding
Done with hand
If done on ground – ground moulding
If done on table- table moulding
B) Machine moulding
Mass production
Clay placed in machine and come out through the opening under pressure
Cut to bricks by steel wires fixed in to frames – wire cut bricks
9. c) Drying of bricks
Done under sunlight in special prepared yards
Stacked in row and dried for a period of 5to 12 days
D) Burning of bricks
i) Clamp burning
Clamps are temporary structures
Bricks are stacked in layers wth certain gap into it
Firewood is iserted in these gaps and fired
Burning is continued for 6 to 8 weeks
Possible only in summer
ii) Kiln burning
Permanat structures
Rate of buring high
Burned to correct size and shape
Initial investment is high
10. Properties:-
should have uniform copper color
Should be uniform in shape and should be of standard size.
Brick when broken should show a uniform compact and heterogeneous structure free from voids
Bricks should not absorb water more than 20% for first class bricks and 22% for second class bricks
when soaked in water for 24 hrs.
Should be hard enough. No impression should be left when scratched.
Should not break into pieces when dropped from a height of 1 m.
Brick when soaked in water for 24 hrs, should not show deposits of white salts when allowed to dry in
shade.
11. Properties:-
Should have low thermal conductivity and should be sound proof.
Crushing strength of brick should not be below 3.5 N/mm².
Should be table moulded, well burnt and free from cracks with sharp and square edges.
Colour should be uniform and bright.
Bricks should give a good metallic sound when struck with each other.
12. USES OF BRICKS
• Construction of walls, foundation of structures
• Used in construction of bridges and dams
• Used In paving and road works
• Firebricks are used for furnaces , chimneys etc
• Used for ornamental works
13. Test for Bricks (IS 3495 ( Part 4 ) : 1992 )
The following tests are conducted on bricks to decide its suitability for construction works:-
1. Absorption Test
2. Crushing Strength Test
3. Hardness Test
4. Soundness Test
5. Presence of Soluble Salts
6. Shape and Size
7. Structure
8. Warpage
14. Test for Bricks
Absorption Test
Dry weight of brick is noted and then immersed in
water for 16 hrs.
Wet weight is then taken.
Difference in weight indicates the quantity of
water absorbed.
% water absorption should not exceed 20% of dry
weight.
Crushing Strength Test
Tested on Compression Testing Machine (CTM).
Brick immersed in water for 24 hrs. It is then taken
out and excess water is wiped off.
Place the brick on CTM and axial load is applied at
the rate of 14N/mm²/minute till it breaks.
Maximum load at which the brick crushes is noted.
Crushing strength is = load by area of face of brick
Minimum compressive strength is 3.5N/mm² and
for superior quality bricks it is 7 – 14 N/mm².
15. Test for Bricks
Hardness Test
A scratch is made on brick surface with finger nail,
and if no nail impression is left on the surface –
sufficiently hard.
Soundness Test
2 bricks are struck with each other.
Bricks of good quality should not break and will
produce a clear ringing sound.
Structure
brick is broken and structure is examined.
Should be homogeneous, compact and free from
voids, lumps etc.
Presence of Soluble Salts
If present in bricks will cause efflorescence on the
surface.
Immerse the brick in water for 24 hrs and then take
it out and dry in shade.
Presence of gray or white deposit on its surface
indicates the presence of soluble salts.
White or gray deposit on surface – 10%- slight
About 50% - moderate
More than 50% - efflorescence is heavy and the
brick cannot be used for construction.
16. Classification of Bricks
1. Un-burned or sun burned bricks
used for un important temporarty and
cheap works)
2. Burned bricks
A) first class
B) second class
C) third class
D) fourth class
17. First Class Bricks Second Class Bricks Third Class Bricks Fourth Class Bricks
Preparation Machine or table moulded
and burnt in kilns
Ground moulded and
burnt in kilns
Ground moulded and
burnt in clamps.
Ground moulded and
burnt in clamps.
Shape and size Rectangular shape with
sharp edges and uniform
size
Rectangular shape with
sharp edges but slight
irregularities in size
May not have regular
size and shape, slightly
over or under burnt
Over burnt bricks with
irregular shape and size
Crushing strength Not less than 10.5 N/mm² Not less than 7 N/mm² - -
Water absorption Not greater than 15% Not greater than 22% Not greater than 24% -
Structure and
Hardness
uses
Free from cracks, lumps
and fractured surface
should have uniform colour
and texture
superior quality works such
as outer walls, facing works
floors etc
Free from cracks, but
slight flaws and lumps
are permitted.
Internal walls, should be
plastered
Produce dull sound
when struck together
Unimportant and
temporary works
Dark and brittle, not
used in normal
construction works.
Over burned, not used
for building
construction, used as
aggregate in concrete
and for flooring
18. 2. CEMENT BLOCKS
Used in building construction because of its:
Light weight
Easy availability
Economical as compared to bricks, stones and concrete blocks.
Manufactured by mixing 60% fine aggregate and 6 to 12mm size coarse aggregate about
40%
Air pockets inside provides thermal and sound insulation to some extent.
Standard Sizes:-
1. 39cm* 19cm* 30cm
2. 39cm* 19cm* 20cm
3. 39cm* 19cm* 10cm
19. Properties of Cement Blocks
1. Appearance – Light gray colour, rough texture and is suitable for most types of plastering.
2. Sound insulation and Acoustic Control – Air voids inside cement blocks provide sound and
thermal insulation.
3. Fire Resistance – Non- combustible, 20cm thick blocks provide fire resistance of 3 hrs.
4. Durability – Resistant to freeze and thaw cycles, decay and sulphate attack.
5. Workability – Not easy to handle as in case of brick, but placing a single block will cover up an
area of about 4 times as that covered by brick.
6. Compressive Strength – 3 N/mm²
7. Thermal Conductivity – 0.11 W/Mk
8. Can be easily recycled.
20. Applications of Concrete blocks
a) Steps
b) To build foundation walls
c) To build basement walls
d) To build partition walls
e) To build exterior walls
f) For paving applications
g) It can also be used for the construction of water storage tanks
21. Advantages of Concrete blocks
a) Inexpensive
b) Block walls are thinner and the Blocks are lightweight
c) Durable
d) Easy to build with even during monsoon.
e) Fireproof
f) Low maintenance
g) Adequate strength and structural stability
h) Environmentally Eco friendly
i) Reduce cement mortar consumption by 60 %
22. Bricks may be broadly classified as:
(i) Building bricks
(ii) Paving bricks
(iii) Fire bricks
(iv) Special bricks.
(i) Building Bricks: These bricks are used for the construction of walls.
(ii) Paving Bricks: These are vitrified bricks and are used as pavers.
(iii) Fire Bricks: These bricks are specially made to withstand furnace
temperature. Silica bricks belong to this category.
(iv) Special Bricks: These bricks are different from the commonly used building bricks
with respect to their shape and the purpose for which they are made.
Some of such bricks are listed below:
(a) Specially shaped bricks
(b) Facing bricks
(c) Perforated building bricks
(d) Burnt clay hollow bricks
(e) Sewer bricks
( f ) Acid resistant bricks.
23. a) Specially Shaped Bricks: Bricks of special shapes are manufactured to meet the requirements of different
situations. Some of them are shown in Fig.
(b) Facing Bricks: These bricks are used in the outer face of masonry. Once these bricks are provided,
plastering is not required. The standard size of these bricks are 19 × 9× 9 cm
24. (c) Perforated Building Bricks: These bricks are manufactured with area of perforation
of 30 to 45 per cent. The area of each perforation should not exceed 500 mm2. The
perforation should be uniformly distributed over the surface. They are manufactured in
the size 190 × 190 × 90 mm and 290 × 90 × 90 mm.
(d) Burn’t Clay Hollow Bricks: Figure shows a burnt clay hollow brick. They are light in
weight. They are used for the construction of partition walls. They provide good
thermal insulation to buildings. They are manufactured in the sizes 190 × 190 × 90
mm, 290 × 90 × 90 mm and 290 × 140 × 90 mm. The thickness of any shell should not be
less than 11 mm and that of any web not less than 8 mm.
(e) Sewer Bricks: These bricks are used for the construction of sewage lines. They
are manufactured from surface clay, fire clay shale or with the combination of these.
They are manufactured in the sizes 190 × 90 × 90 mm and 190 × 90 × 40 mm. The
average strength of these bricks should be a minimum of 17.5 N/mm2 . The water
absorption should not be more than 10 per cent.
( f ) Acid Resistant Bricks: These bricks are used for floorings likely to be subjected to
acid attacks, lining of chambers in chemical plants, lining of sewers carrying industrial
wastes etc. These bricks are made of clay or shale of suitable composition with low lime
and iron content, flint or sand and vitrified at high temperature in a ceramic kiln.
25. CEMENT
Most inevitable material for construction purposes.
Has got good adhesive and cohesive properties.
Obtained by burning (at high temperatures) and crushing argillaceous and calcareous
( lime and clay).
Most common type is the Ordinary Portland Cement (OPC) – Calcareous and
Argillaceous material in the ratio 4:1.
Major component in Calcareous material - CaCO₃ ( Ex. Chalk, marine shell, cement rock
etc.)
Major component in Argillaceous material - Clay (Ex. Blast furnace slag, slate etc.)
26. Composition of OPC
S.No Ingredient Range in % Properties
1. Lime (CaO) 62 – 67 Most important constituent.
Excess lime makes the cement unsound and cause it to expand and
disintegrate.
Deficiency of lime decreases the strength and quick setting
2. Silica (SiO₂) 17 – 25 Impart strength with the formation of C₃S and C₂S.
Excess silica increases the strength but it also increases the setting time too.
3. Alumina (Al₂O₃) 3 – 8 Impart quick setting property to the cement.
Excess alumina weakens the cement
4. Calcium Sulphate (CaSO₄) 3 – 4 In the form of gypsum. Used to increase the initial setting time.
5. Iron Oxide (Fe₂O₃) 3 – 4 Imparts colour, hardness and strength to cement.
6. Magnesia (MgO) 0 – 3 Imparts colour and hardness, excess MgO makes it unsound.
7. Sulphur (S) 1 – 3 Small amount of S is useful in making the cement sound, Excess- unsound
8. Alkalies 0 – 1 Excess alkalies causes efflorescence and staining.
27. Setting Action of Cement
Setting of cement is the process of hardening of cement paste into a hard solid mass.
When water is added to cement it forms a thick paste. Gradually as time passes, it transforms into a non- plastic
rigid mass.
The strength of cement paste goes on increasing with time – 70% of final strength attained in 28 days and 90% of
its final strength in one year.
Tri-calcium aluminate (C₃A) 4 – 14% Formed within 24 hrs
Tri-calcium alumina ferrite (C₄AF) 10 – 18% Formed within 24 hrs
Tri-calcium silicate (C₃S) 45 – 65% Formed within a week
Di-calcium silicate (C₂S) 15 – 35% Formed very slowly
28. Properties of Cement
1. Physical properties
2. Chemical properties
Chemical analysis is done to ensure that the impurities in cement are within
prescribed limits.
Colour
Fineness
Setting Time
Soundness of
Cement
Property Ratio
Ratio of % of alumina to that of iron
oxide Not less than 0.66
Ratio of % of lime to that of alumina,
iron oxide and silica
Not less than 0.66 and not
greater than 1.02
Total loss on ignition Not greater than 4 %
Total sulphur content Not greater than 2.75%
Weight of insoluble residue Not greater than 1.5%
Weight of Magnesia Not to exceed 5%
29. Physical Properties of Cement
1. Colour
Uniform colour
Typical cement colour is grey with a light
greenish shade
Free from lumps and should be cool when felt
with hand.
2. Setting Time
• Initial setting time is the time at which the
cement past starts losing its plasticity should
not be less than 30 minutes
• Final setting time is the time at which the
cement paste completely loses its plasticity
and attains the shape of mould should not be
more than 600 minutes.
3. Fineness
Measure of mean size of grains in cement.
Measured by sieve test.
When sieved through 90 micron sieve, the
quantity of residue left after sieving should not
exceed 10% ( as per IS 269-1976).
Fineness also measured by permeability test –
for that the specific surface area should not be
less than 2250cm²/gm.
30. Physical Properties of Cement
4. Soundness of Cement:-
It is the capacity of cement to form a hard and strong mass on setting.
Determined by the Le Chatelier Apparatus.
Cement paste after setting should not undergo large change in its volume as
this may lead to disintegration and cracking.
For OPC, the expansion measured with this apparatus should be less than
10mm
31. Grades of Cement
Grade is the 28 days strength when tested as per Indian Standards under standard
conditions.
OPC is classified into 3 Grades – 33, 43 and 53 grades denoted as C33, C43 and C53.
Cement is graded according to its compressive strength.
If the cement is a 33-grade cement, then it has a compressive strength equivalent to 33
MPa (33 N/mm²).
32. Grades of Cement
SI.No Grade of Cement Specifications
1.
33 Grade Cement
(IS: 269 – 1989 )
Compressive strength after 28 days is 33 N/mm²
Used for general construction works in normal environmental conditions.
Cannot be used where higher grades of concrete are used (above M – 20)
Not widely used.
2.
43 Grade Cement
(IS: 8112 – 1989 )
Minimum 28 days compressive strength – 43 N/mm²
Most widely used cement for general construction works such as construction
of residential, commercial and industrial buildings, roads, bridges, flyovers,
irrigation projects etc.
Suitable for all applications – RCC, Plastering, Masonry etc.
3.
53 Grade Cement
(IS: 12269 – 1987 )
Minimum 28 days compressive strength – 53 N/mm²
Used for construction of high rise buildings, bridges, chimneys and pre-
stressed structures where high grade concrete is used.
When used for higher grades of concrete ( M30 and above), this saves around
10- 15% in cement consumption and 5-8% saving in steel consumption.
53 S – special grade cement used for construction of sleepers.
33. Types of Cement
Composition
Purpose
Rapid Hardening Cement Increased Lime content
Attains high strength in early days it is used in concrete where
form work are removed at an early stage.
Quick setting cement Small percentage of aluminium sulphate as an accelerator and
reducing percentage of Gypsum with fine grinding
Used in works is to be completed in very short period and
concreting in static and running water
Low Heat Cement Manufactured by reducing tricalcium aluminate It is used in massive concrete construction like gravity dams
Sulphates resisting Cement It is prepared by maintaining the percentage of tricalcium
aluminate below 6% which increases power against sulphates
It is used in construction exposed to severe sulphate action by
water and soil in places like canals linings, culverts, retaining
walls, siphons etc.,
Blast Furnace Slag Cement It is obtained by grinding the clinkers with about 60% slag and
resembles more or less in properties of Portland cement
It can used for works economic considerations is predominant.
High Alumina Cement
It is obtained by melting mixture of bauxite and lime and
grinding with the clinker it is rapid hardening cement with
initial and final setting time of about 3.5 and 5 hours
respectively
It is used in works where concrete is subjected to high
temperatures, frost, and acidic action.
White Cement It is prepared from raw materials free from Iron oxide.
It is more costly and is used for architectural purposes such as
precast curtain wall and facing panels, terrazzo surface etc.,
Coloured cement It is produced by mixing mineral pigments with ordinary
cement.
They are widely used for decorative works in floors
Pozzolanic Cement It is prepared by grinding pozzolanic clinker with Portland
cement
It is used in marine structures, sewage works, sewage works
and for laying concrete under water such as bridges, piers,
dams etc.,
Air Entraining Cement
It is produced by adding indigenous air entraining agents such
as resins, glues, sodium salts of Sulphates etc during the
grinding of clinker.
This type of cement is specially suited to improve the
workability with smaller water cement ratio and to improve
frost resistance of concrete.
Hydrophobic cement It is prepared by mixing water repelling chemicals
This cement has high workability and strength
36. Cement concrete is an artificial building material that is obtained
by mixing together cement, fine aggregate, coarse aggregate
and water in suitable proportions.
Cement acts as the binding material and it forms a paste with
water and thus hold the F.A and C.A together to form a solid
mass.
Strength of concrete depends mainly on its ingredients, their
relative quantities and the manner in which they are mixed and
placed.
Ingredients of Concrete:-
1. Cement
2. Sand (fine aggregate)
3. Stone chips or boulders (coarse aggregates)
4. Water
37. PLAIN CEMENT CONCRETE (P.C.C)
The cement concrete in which no reinforcement is provided is
called plain cement concrete or mass cement concrete.
This type of concrete is strong in taking compressive stresses but
weak in taking tensile stresses.
USE:
Plain cement concrete is commonly used in for foundation work
and flooring of buildings.
38. Ingredients of Concrete (P.C.C)
Cement Fine Aggregate Coarse Aggregate Water
Most important
ingredient.
Function:- To bind the
F.A & C.A together.
OPC is the most
commonly used cement
for concrete.
Other varieties of
cement such as water
proof cement, rapid
hardening cement and
high alumina cement are
used under certain
circumstances.
As per IS 383-1970,
F.A are inert or
chemically inactive
material which passes
through 4.75mm IS
sieve.
Example – River sand,
crushed stone, crushed
gravel etc.
Function :- fills all the
open spaces in between
the coarse particles
thereby reducing the
porosity of the final
mix and thus enhancing
strength.
As per IS 383-1970,
C.A are inert or
chemically inactive
material which are
retained on 4.75mm IS
sieve.
Example – uncrushed
gravel, broken bricks,
crushed stone etc.
Function :- To act as
the main load bearing
component of the
concrete, thus making
the concrete strong and
tough.
Governs the important
properties related to
concrete such as
durability, strength and
water tightness.
Functions :-
1. Act chemically with
cement to form a paste
for binding the
aggregates.
2. To make the concrete
workable.
W:C for Medium &
High strength concrete
is 0.6 and 0.35
respectively.
39. Properties of Freshly Prepared Concrete
1. Workability :- It is the ease with which concrete can be mixed,
transported and placed in position. Good quality concrete should
possess good mix ability, transportability and compact ability.
2. Segregation:- Defined as separating out of the constituents of a
concrete mix during transportation of freshly prepared concrete.
3. Bleeding :- Defined as separation of water or mortar from the
freshly prepared concrete.
Due to high water content in the mix
Results in the formation of a porous, weak and non-durable concrete
at the top of the placed concrete.
40. Grades of Concrete, P.C.C (as per IS 456:1978)
Grade of
Concrete
Compressive Strength
of 15 cm cubes at 28
days (N/mm²)
Mix Ratio Nature of Work
M₁₀
10
(Medium Strength)
1: 3: 6
1: 4: 8
1: 5: 10
For culverts, Retaining walls etc.
Mass concrete works for heavy walls,
foundations etc.
M₁₅ 15
(High Strength)
1: 2: 4 For all general R.C.C works in building
such as beam, column, slab, lintel, staircase
etc.
M₂₀ 20
(Higher strength)
1: 1½: 3 Water retaining structures, piles, pre-cast
structures etc.
M₂₅ 25
(Very High Strength)
1: 1: 2 Heavily loaded columns and beams
M₃₀ 30
M₃₅ 35
M₄₀ 40
41. Properties of Hardened Concrete
1. Strength :- Should be strong enough to withstand the stresses induced on it. Strength of
concrete i.e., Characteristic Strength (fck) is measured in N/mm². The compressive strength
is also used for specifying the grade of concrete.
2. Durability:- It is the ability of concrete to resist weathering agents, chemical actions, fire,
wear etc. Durability depends upon the quality of aggregates and the water – cement ratio.
3. Workability :- A workable concrete should not show any segregation or bleeding, i.e., the
materials should not separate out or the excess water should not come upto the surface.
Workability of concrete is measured by 2 tests- Slump Test and Compaction Factor Test.
4. Impermeability:- Ability of concrete to resist the penetration of water. Good concrete
should be impermeable after hardening.
5. Shrinkage :- Concrete experiences shrinkage during hardening. Depends on the
constituents of concrete, atmospheric temperature and size of structure. Minimized by
using designed quantity of W:C ratio and by proper curing.
42. Properties of Hardened Concrete
6. Creep:- Defined as the time dependent elongation of concrete structure under the action of
external loads. Depends on W:C ratio, nature of aggregates and its grading, intensity and
duration of loading, humidity of air, and age at the time of loading.
7. Fire Resistance:- Has got good fire resisting property and acts as a good insulator.
8. Density:- Weight density of concrete – 22 kN/m³ to 23.5 kN/m³ (as per IS 875-1987)
9. Resistance to wear- gives a hard surface capable of resisting abrasion.
10. Elasticity of concrete – concrete behaves elastically only upto 10-15% of its ultimate
strength.
11.Free from corrosion and there is no appreciable effects of atmospheric agents on it.
12. It can develop good bondage with steel.
13. It continues to harden and attains more strength as time passes.
43. Advantages of P.C.C
Concrete can be readily moulded into durable
structural elements of different size and shapes
High compressive strength.
Free from corrosion and not affected by
weathering.
Concrete forms a hard surface for resisting
abrasion.
Hardens with age and process of hardening
continues for a long time
Provides good bond with reinforcement, bricks,
stones etc.
Possess sufficient plasticity.
More economical than steel.
Acts as an impervious body on setting
Low tensile strength.
High self weight.
Low resistance to cracking
Not suitable for speedy construction.
Low ductility.
Reuse of the structure made with concrete
is not possible.
Disadvantages of
P.C.C
44. Reinforced Cement Concrete (R.C.C)
P.C.C is very strong in compression but at the same time it is very weak in tension.
Due to this property of P.C.C, it cannot be used for structures which has to carry
tensile loads.
The combination of plain concrete and steel, by which the combined structure can
resist both tension and compression, is known as Reinforced Cement Concrete
(R.C.C).
Properties:-
1. R.C.C develops very good bond with steel, thereby allowing the excess stress acting
in the concrete to be transmitted on to steel.
2. Cement grout protect the reinforcement from corrosion and at the same time, it
does not chemically react with the reinforcement.
3. The coefficient of linear expansion of concrete and steel are nearly same. Hence,
no internal stresses are developed due to temperature variations.
45. Advantages of R.C.C over P.C.C
1) Economical due to its long life.
2) Durable and fire resistant.
3) More rigid than P.C.C structures.
4) Not affected by termites, fungus or such other insects.
5) Well compacted R.C.C structures are impermeable to moisture
penetration.
6) Less maintenance cost.
7) Materials used in R.C.C constructions are easily and abundantly
available.
8) Can be easily moulded into any shape because of the fluidity of
concrete and flexibility of reinforcement.
47. Manufacture of Concrete or Method of
Making Concrete
1. Proportioning of concrete ingredients.
2. Measurement or Batching of materials.
3. Mixing of concrete.
4. Transporting and placing of concrete.
5. Compaction of concrete.
6. Curing of concrete and removal of form-work.
48. PLACING OF CONCRETE
After mixing of concrete it should be placed within 30min of
adding of water.
It should be quickly transported to the place of lying by means of
iron pans manually, in wheel barrows, by pumping or by cranes.
In placing, concrete should be laid in thin layers. Each layer being
thoroughly consolidated, before the next one is laid.
Concrete should not be dropped from a height as it would cause
segregation of aggregates.
49. COMPACTION OF CONCRETE
Compaction of concrete is very important in developing qualities like strength,
durability, imperviousness by making the concrete dense and free from voids.
In case of RCC compaction is done by pinning with an iron rod or even with
trowel blade.
Excess temping should be avoided as otherwise water, cement and finer
particles would come to the surface and results in non uniform concreting.
In case of important and big works, compaction of concrete is done with
vibrator.
Use of vibrator is best and the most efficient way of compacting concrete. It
gives very dense concrete.
Care should be taken not to make excessive use of vibrators otherwise the
concrete becomes non homogeneous
50. CURING OF CONCRETE
The process of keeping concrete wet to enable
it to attain full strength is known as curing.
The objective of curing is to prevent loss of
moisture from concrete due to evaporation or
because of any other reasons.
Curing should be done for a period of three
weeks but not less then 10 days.
51. CURING OF CONCRETE
To do curing, any one of the following method can be used.
i. The surface of concrete is coated with a layer of bitumen or
similar other waterproofing compound which gets into the pores
of concrete and prevent loss of water from concrete.
ii. Concrete surface is covered with waterproof paper or with a
layer of wet sand. It could also be covered with gunny bags.
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PLINTH AREA
Plinth area built up covered area of a building measured at floor level at any storey.
Plinth area is calculated by taking the external dimension of the building at the floor level excluding plinth off-sets, if any
courtyards, open areas, balconies cantilever projections are not included in plinth area.
Supported porches (other than cantilevered) are included in the plinth area
The following shall be included in the plinth area.
1. All floor area of walls at the floor level excluding plinth of sets if any.
2. Internal Shafts for sanitary installation provided these do not exceed 2 sq m. in area air condition ducts, lifts etc.
3. The area of parasites and the area of mufti at terrace level.
4. Area of porch other than cantilevered
The following shall not be included in the plinth area.
Area of loft
Internal sanitary shafts provided these do not more than 2 sq m. in area.
In enclosed balconies
Towers, sunshade, domes, etc. projecting above the terrace level, not forming a storey at the terrace level.
Architectural bonds, cornices etc.
Sunshade, vertical sun breakers of box Louvers projecting out
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What is Carpet Area?
As the name suggests, carpet area means the area of the property where you can lay your carpet, measured wall to
wall (Checkout the illustration below). This is the actual area which you can call your personal space and you should be really
concerned about.
Areas included in Carpet Area
All Rooms – Living Room, Bedrooms, Dining Room, Dressing Room, Other Rooms.
Kitchen and Bathrooms
Stores and Balconies
Areas not included in Carpet Area
External and Internal walls
Common Areas
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What is Built Up Area/ Plinth Area?
Built Up Area or Plinth Area is the total covered area of the apartment or commercial property unit. It can be
calculated by adding areas of utility ducts within property unit, internal and external walls to the carpet area (Checkout
the illustration below). As a rule of thumb, built up area can be calculated by adding 10% loading factor on carpet area.
This term is not so important while buying a property as almost all developers sell the property on super built up area.
However, this term becomes important while dealing with government departments for eg. In many states, property
taxes are levied on built up area/ plinth area.
Areas included in Built Up Area/ Plinth Area
Entire carpet area
Internal and External Walls
Utility Ducts within walls of the unit
Areas not included in Built Up Area/ Plinth Area
Common Areas
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What is Super Built Up Area?
Super Built Up Area means built up area plus common areas proportioned to a unit (Checkout the illustration below).
As a rule of thumb, the super built up area can be calculated by adding a loading factor to the carpet area, which may
vary from 15% to 50%. The lower the factor the better it is for you as a customer as you get a higher carpet area for the
same amount. The biggest catch is the calculation of common areas, where you should pay most attention to.
Areas included in Super Built Up Area
Entire Built Up Area
Common Areas – lobby, lift ducts, staircases, pipe ducts/ shafts, air ducts, covered community centres/ clubs, other
covered common facilities.
Areas not included (generally should not be included) in Super Built Up Area
Roof Terrace
Open Areas like parks, gardens, play areas etc.
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STEEL – GENERAL FACTS
Steel – alloy of iron and carbon with traces of other elements.
Total carbon content in steel varies from 0.25 to 1.5 %.
Smaller the carbon content, its property is similar to wrought iron and as the carbon
content increases its characteristics is similar to cast iron.
Steel is strong both in tension and compression, hence it is suitable for all construction
works.
NOTE:-
Wrought Iron is the purest form of iron with very low carbon content (less than 0.15 %)
Cast Iron has a carbon content of 1.7 – 4.5 %.
Cast iron is granular and can take up only compressive stresses and hence its use is
limited to compression members.
Wrought iron is fibrous and it is suitable to resist tensile stresses.
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Types of Steel and Its Purposes
Name of Steel Carbon Content (%) Purpose
Mild Steel Less than 0.25
For making motor body, sheet metal, boiler plates,
structural steel etc.
Medium Carbon Steel 0.25 – 0.75 For making rails, Hammers, Springs etc.
High Carbon Steel 0.75 – 1.25
For making chisels, Hammers, Saw, Smithy Tools,
Drills, Stone Masons Tool, Axes
Stainless Steel Greater than 1.25 For making architectural panels, curtain walls etc.
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Uses Of Steel
1. As structural material in trusses, beams and other light frames.
2. As non-structural components for grills, stair balustrades, windows and doors.
3. Mechanical services in the form of steel pipes, tubes, tanks, ducts etc.
4. Soft and malleable steel is used for rolling into thin sheets.
5. Very soft and ductile sheet are used for drawing into thin sheets.
6. Very hard and brittle steel is used for making tools.
7. Sanitary and sewer fittings, corrugated sheets etc.
8. Steel are highly elastic, ductile, malleable, forgeable and weldable. They regain the
magnetic properties as iron.
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Market forms of steel
• Steel – used extensively in modern multi-storeyed buildings.
• Construction using steel is economical for Buildings more than 10 storeys.
• Commonly adopted for factory buildings due to the easiness in erection and heavy load carrying
capacity.
Market Forms:-
1. Angle Section 7.
Round Bars
2. Channel Section 8.
Expanded Metals
3. T – Section 9.
Plates
4. I – Section 10. Corrugated Sheets
5. Flat Bars 11. Pipes, Tubes and Sheets
6. Square Bars 12. Ribbed Tor Steel
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Angle section
1. Angle sections have 2 legs. If the 2 legs are of equal
length, then they are known as Equal Angle Section
and other wise Unequal Angle Section.
2. Size of Equal Angle Section – 20mm *20mm * 3mm
to 200mm *200mm * 25mm and their corresponding
weights are 9N/m and 736N/m.
3. Size of Unequal Angle Section – 30mm*20mm*3mm
to 200mm *150mm * 18mm ( weights – 11N/m AND
469N/m).
Uses :-
Used in construction of steel roof trusses, steel
columns, steel beams, stiffners in huge girders etc.
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Channel section
1. Consists of a web and two equal flanges.
2. Usually designated by the height of the
web and width of flange.
3. Size – 100mm * 45mm to 400mm *
100mm with weight as 58 N/m and
494N/m respectively.
Uses:-
Widely used as structural members of steel
framed structures.
For the construction of beams, steel bridges,
crane girders, built – in columns etc.
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t- section
1. Consists of a web and flange.
2. Designated by its overall width and
depth.
3. Available sizes – 20mm *20mm * 8mm
to 150mm * 150mm * 10mm with
weight as 9 N/m and 228 N/m
respectively.
Uses:-
Widely used as members of steel roof
trusses, steel bridges, chimneys, to form
built – up sections etc.
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I – section
1. Commonly known as Rolled Steel Joists (R.S.J)
2. Consists of 2 flanges and a connecting web.
3. Designated by overall depth, width of flange and
weight per metre length.
4. Available size range – 75mm * 50mm at 61 N/m to
600mm * 210mm at 995N/m
Uses:-
Suitable for columns, beams, lintels, etc.
Unequal I – Sections with heavy weight are used as
rails.
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Expanded metals
• Formed by cutting and expanding either plain sheets or
ribbed sheets of steel.
• A diamond mesh appearance is formed through out the
area of the metal (Diamond Mesh or Rib Mesh).
• Has sizes 30 mm to 150 mm across the shorter length of
the mesh and is available in length 1 to 3 metre and
width 5m.
Uses:-
As a reinforcement in ferro cement construction
reinforcing foundation, road floors, bridges etc.
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Flat, Square And Round BARS
Flat Bars Square Bars Round Bars
1. Available in suitable
widths varying from 3 to
40 mm.
2. Widely used for the
construction of steel
grill works, windows
and gates.
1. These are bars with square c/s.
2. Size of square bar – 5mm
square to 25mm square and
their corresponding weight as
2N/m & 49N/m.
3. Widely used in the construction
of steel grill works, windows,
gates etc.
1. These bars are with circular
c/s.
2. Available in diameters
varying from 5 to 25mm
and their corresponding
weight as 1.5N/m &
38N/m.
3. Used as reinforcement in
concrete structures,
construction of steel grill
works etc.
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Corrugated sheets
1. Formed by passing steel sheets
through grooves. These grooves
bend and press sheets, and
corrugations are formed on the
sheets.
2. These corrugated sheets are
galvanized and they are known
as galvanized iron sheets or G.I
sheets.
Use:-
» Widely used as roof covering
material.
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Plates , & Pipes, Tubes and Steel Sheets
Plates Pipes, Tubes and Steel Pipes
Plate sections of steel are available in
different sizes with thickness varying from
5 to 50mm and their corresponding
weights are 392 N/mm² & 3925 N/mm².
Uses :-
1. Used to connect steel beams for extension
of length.
2. For carrying tensional force in steel roof
trusses.
3. Used to form built up sections of steel.
Pipes are used for light columns and other
structural purposes.
Primary use of pipe is to use it as liquid conduits.
Tubes of different shapes are available in market
like round, square and rectangular.
Tubes are used for framing roof truss and for light
structural works, scaffolding etc.
Pipes over 15cm are sometimes casted as
corrugated pipes, due to the difficulty of threading
the pipe.
82. Mild steel
( Corrosion Resistant Steel – crs )
General
Mild steel is corrosion resistant, so they can
increase the life of structure made up of it.
Chemical composition – 0.1% carbon, 0.65%
phosphorous and 0.06% sulphur.
Yield strength – 250 N/mm² and it is called
Fe250.
Uses:-
Used for the construction of light and heavy
engineering structures like ship, railway,
building, automobile and electrical industries.
Mainly 2 market forms – Fe 415 and Fe 500
Available diameters – 8,10, 12, 16, 20, 25,
28, 32, 36, 40 mm)
Properties:-
1. More tougher and more elastic than wrought iron.
2. Malleable and ductile.
3. Not easily affected by salt water.
4. Melting point is about 1400ºC
5. Specific Gravity 7.8
6. Strong in both tension and compression.
7. Can be magnetised permanently.
8. Can be readily forged and welded.
9. Fibrous structure for mild steel.
83. Ribbed Tor Steel
i. Most commonly used steel bar for concrete reinforcement is TOR steel.
ii. Other names – CTD bar, deformed steel bar, twisted steel bar, HYSD bar and CWD bar
iii. TOR steel bars of grades TOR40, TOR50, TOR55 and TOR60 are available.
iv. Available sizes – 6 to 50mm diameter with corresponding weight 2.22 N/m & 154.10 N/m
The ribbed tor steel rods have ribs or projections on their surface and are produced by controlled
cold twisting of hot rolled bars.
Due to the presence of ribs, yield stress, tensile strength and bond strength with concrete is
improved.
i. Used for general concrete reinforcement in buildings, roads, bridges, sea wall, dam, culverts etc.
85. HYSD Steel
(High Yield Strength Deformed Steel)
General:-
HYSD steel is having a yield
strength of 415Mpa
Permissible tensile stress of
230Mpa and proof stress of
0.2% are uses as reinforcement
in R.C.C works.
Also known as Fe 415 HYSD
bars.
Advantages of HYSD steel Bars
i. It is possible to bend these bars through 180º
without any cracks.
ii. It has 65% greater yield strength.
iii. It has 80% greater bond strength.
iv. Satisfactory and easy weldability.
v. Provides 20% more factor of safety due to hyper
resistance.
vi. Suitable for both tension and compression.
vii. Net economy is achieved in cost up to 40% in
tension side and 30% in compression side in
comparison with mild steel.
89. Surveying
“Surveying is the art of and science of determining the relative positions of various points
or stations on the surface of the earth by measuring the horizontal and vertical distances,
angles, and taking the details of these points and by preparing a map or plan to any
suitable scale.”
91. Objective of Surveying
The object of surveying is to prepare a map or plan to show the relative positions of the
objects on the surface of the earth.
The map or plan is drawn to some suitable scale.
It also shows boundaries of districts, states, and countries too.
It also includes details of different engineering features such as buildings, roads, railways,
dams, canals etc.
96. Uses of Surveying
The surveying may be used for following purposes:
To prepare a topographical map which shows hills, valleys, rivers, forests, villages, towns
etc.
To prepare a cadastral map which shows the boundaries of fields, plots, houses and other
properties..
To prepare an engineering map which shows the position of engineering works such as
buildings, roads, railways, dams, canals.
100. Uses of Surveying
To prepare a contour map to know the topography of the area to find out the best
possible site for roads, railways, bridges, reservoirs, canals, etc.
Surveying is also used to prepare military map, geological map, archaeological map etc.
For setting out work and transferring details from the map on the ground.
106. Fundamental Principles of Surveying
Two basic principles of surveying are:
Always work from whole to the part, and
To locate a new station by at least two measurements ( Linear or angular) from fixed
reference points.
107. Fundamental Principles of Surveying
Always work from whole to the part:
According to the first principle, the whole survey area is first enclosed by main stations
(i.e.. Control stations) and main survey lines. The area is then divided into a number of
divisions by forming well conditioned triangles.
109. First Principle of Surveying
The main survey lines are measured very accurately with precise survey instruments.
The remaining sides of the triangle are measured.
The purpose of this method of working is to control accumulation of errors.
During measurement, if there is any error, then it will not affect the whole work, but if
the reverse process is followed then the minor error in measurement will be magnified.
110. Second Principles of Surveying
To locate a new station by at least two measurements ( Linear or angular) from fixed
reference points.
According to the second principle the points are located by linear or angular
measurement or by both in surveying. If two control points are established first, then a
new station can be located by linear measurement. Let A & B are control points, a new
point C can be established.
111. Fundamental Principles of Surveying
Following are the methods of locating point C from such reference points A & B.
The distance AB can be measured accurately and the relative positions of the point can be
then plotted on the sheet to some scale.
(a) Taking linear measurement from A and B for C.
(b) Taking linear measurement of perpendicular from D to C.
(c) Taking one linear measurement from B and one angular measurement as ∕ ABC
112. Fundamental Principles of Surveying
Taking two angular measurement at A & B as angles / CAB and / ABC.
Taking one angle at B as / ABC and one linear measurement from A as AC.
