construction materils 1.0

SHREE DWARKESHO JAYATI

CONSTRUCTION MATERIALS

INTRODUCTION:

Variety of materials used for any building construction. Strength and stability of any building is depending upon construction materials. Approximate 50% of total cost is the cost of materials.

Construction materials are mainly divided into two parts.

Construction Materials

Naturally available Materials Artificial Materials (Manmade materials)

1. Timber 1. Cement2. Clay or Soil or Earth 2. Lime3. Fine Aggregates (sand) 3. Bricks 4. Gravels 4. Steel

5. Stones 6. Ceramics

7. Glass 8. Paints and Varnishes 9. Plastics

Bricks:

Bricks are made of clay. It is rectangular in shape and of standard size.

Notes: 1. Brick is made of clay. Clay is molded to form rectangular block of standard size, which are dried and then burnt into clamp or in a flame kiln.Clamps: Both bricks and fuels are placed in alternate layersFlame kilns: It is constructed with rectangular, circular or oval shape which may be under ground or over ground.

Composition of Bricks:

Alumina 20% to 30% Gives plasticity to the earth so it can be mould

Silica 50% to 605 Prevents cracking, shrinking and warping of raw bricks and impart uniform shape

Lime <5% Prevents shrinkage of raw bricksIron oxide 5% to 6% Impart red colour to bricksMagnesia 0.1% Impart yellow tint to bricks and

decrease shrinkage


Characteristics/ Requirements of Good Bricks:

1. It should be well burnt and of uniform colour (i.e. red or copper)2. It should be of standard size and uniform in shape3. It should be free from voids4. When two bricks are struck with each other, it should gives metallic ringing

sound5. It should not break or crushed in to pieces, when it dropped on flat ground

from 1.0m. height6. It should be hard enough and when scratched by a finger nail, no impression

should be left on bricks surface7. It should have crushing strength or compressive strength more than 5.5N/mm2

8. It should be sound proof and should have low thermal conductivity9. The clay used for bricks should be free from organic matter, salts, pebbles etc.10. It should be easily available and durable

Properties of Good Bricks:

The properties of good brick can be derived from characteristics of a good bricks

1. Bricks are manufactured from naturally available material like clay2. Bricks are red or copper red in colour and having size of 19 cm* 9 cm* 9 cm.3. Bricks are light in weight, durable, low cost materials and easily available 4. The weight of good bricks lies between 3.2 to 3.5 kg.5. The density of good bricks vary from 16kN/m3 to 19kN/m3

6. Water absorption of good bricks shall not be more than 20%

7. Good bricks possess flexural strength more than 1.5N/mm28. Porous bricks conduct heat and sound at slower rate

Types of bricks:

There are two types of bricks: 1. Conventional/ Traditional bricks: size 23 cm* 11.4 cm* 7.5 cm2. Standard bricks: size 19 cm* 9 cm* 9 cm

Classification of Bricks

By manufacture By utility

a) Hand moulded a) 1st class bricksb) Machine moulded b) 2nd class bricks

c) 3rd class bricks d) 4th class bricks


1 st class Bricks:

1. Bricks are sound, well burnt in kilns, rectangular with sharp edges2. It is of best quality and used for superior work and exposed brick work3. Compressive strength should not be less than 10N/mm2

2nd class Bricks:1. Bricks are burnt in clamps and grounded moulded2. Surface is rough and shape is slightly irregular3. Mainly used for ordinary work4. Compressive strength should not less than 7N/mm2

3rd class Bricks:1. Bricks are burnt in clamps and grounded moulded2. Surface is rough, irregular and distorted3. Used for temporary work and less important work

4th class Bricks:1. Bricks are strong but over burnt2. Surface is irregular and have dark colour3. Used to prepare broken bats which are used in foundation concrete

Uses of bricks:

1. Bricks are used for making wall for various building construction2. Bats of bricks are used in foundation work 3. Bricks are used for canal lining, bridges piers, lintel etc.

Importance of Bricks:

1. Bricks are used for making wall for various building construction2. Bats of bricks are used in foundation work 3. Bricks are used for canal lining, bridges piers, lintel etc.4. Bricks gives fire protection, sound/noise insulation and thermal insulation5. Bricks are light in weight hence easy to handle6. Bricks are cheap and easily available materials

Cement:

Cement if defined as a binding material which bound various materials like sand, aggregate etc. together and makes it as solid mass.

It is obtained by burning a mixture of siliceous material (silica), argillaceous material (clay), calcareous material (lime) in a proper proportion.Notes: A mixture of silica, clay, lime, alumina, etc fed in to a rotary kiln in a wet condition and burnt at a temperature around 15000c to 17000c. The clinker is than cooled and ground into a fine powder. To control the setting time 2% to 3% gypsum


is added at the time of grinding. The gray colour fine powder is than paced into a 50g bags.

Composition of cement:

Ingredients % Ingredients

Function of ingredients

Lime(CaO) 60-65 Control strength and soundnessSilica(SiO2) 17-25 Provide strengthAlumina(Al2O3) 3-8 Cause quick setting of cement Iron oxide 2-5 Impart grey colour to cement and

help in fusion of different ingredientsMagnesia(MgO) 0.5-4 Gives colour and hardnessCalcium sulphate(CaSO4)

2-3 Control initial setting time

Sulphur 1-2 Imparts soundness to cementAlkalis 0.5-1.3 Causes expansion and deterioration

of cement

Characteristics/ Requirements of cement:

1. It should be of uniform grey colour and in powder form2. It should be cool and smooth when rubbed between two fingers3. It should not contain excess amount of ingredients4. It should offer a good resistance against moisture, weathering effect5. It should be free from any hard lumps

Properties of cement:

1. It is in fine powder material of grey colour and considered as fine binding material

2. It is easy to mix with sand, water and aggregate3. It possesses good plasticity4. It provides strength to masonry 5. It possesses good resistance against moisture and weathering effect

Hydration of cement:

When water is added or mixed with cement, ingredients of cement chemically reacts with the water, this chemical reaction between water and cement is known as hydration of cement.


The following compounds are formed during this process:

Compound % FunctionTricalcium silicate (C3S)(3CaO, SiO2)

About 70% to 80% of cement contributed

Produce lots of heat and contribute to develop a early strength of cement (During first seven days)

Diacalcium silicate (C2S)(2CaO, SiO2)

Hydrates slowly and contribute to develop a later stage strength (28 days)

Tricalcium aluminate (C3A)(3CaO, Al2O3)

14% Responsible for initial strength of cement (24 hours). It is less stable

Tera-calcium alumino-ferrite (C4AF) (4CaO, Al2O3, Fe2O3)

10% to 15%

Less important

Types of cement: 1. Ordinary Portland cement:

This type of cement is widely used. It has medium hardening rate and heat generation due to that widely

used in major construction It offers resistance against shrinkage and cracking. When water is added in OPC, it reacts with water and generates four

major compounds (C3S), (C2S), (C3A) and (C4AF). [function of four compound gives in above table]

2. Rapid hardening Portland cement: This type of cement gets a high early strength compare to OPC. Highly early strength is mainly due to C3S. Lime contain is more compare to OPC due to that large amount of heat

generated during hydration so it is not suitable for mass concrete. Cement sets rapidly so construction work carried out speedily and it

required short period of curing It is used in repairing of roads, bridges and concreting in cold weather.

3. Quick setting cement: The quick setting cement is produced by adding a small amount of

aluminum sulphate and by reducing % of gypsum. These types of cement start setting within five minutes after adding of

water and become hard within 30 minutes. It is finer than OPC. The addition of aluminium sulphate and fineness of grinding are

responsible for accelerating the setting time action It is used when concreting is to be done under water or running water.

4. Pozzuolana cement:


Pozzuolana is a volcanic powder. This types of cement is manufactured by uniformly blending of Portland cement with Pozzuolana (10% to 30%)

The rate of development of strength of these types of cement is slower than OPC hence it required longer curing period.

It has no binding value itself but when mixed with cement it react with excess lime and generate more stable compound and make it more durable

It has more resistance against chemical attack and therefore use for marine works.

It is also used in mass concrete like dams, weirs, bridges etc. 5. Blast furnace slag cement:

About 60 to 70% of slag obtained from blast furnace is used to prepare blast furnace cement

Its strength in early days are less and hence it requires longer curing period

It is economical as slag (west product in the manufacturing process of pig-iron is used) and durable but not suitable for dry acid zone.

6. Coloured cement: The cement of desired colour may be obtained by mixing 5% to 10%

minerals pigments with OPC. The coloured cement is widely used for finishing of floors, external

surfaces etc. The following are the pigments which gives desired colours.

Pigments Colour

Chromium oxide Green

Cobalt Blue

Iron oxide Brown, Red or Yellow according to its proportion

Manganese dioxide Black or Brown

7. White cement: The raw materials used for this cement should be free from colouring

pigments. It is white in colour and it is used for floor finish, plaster work,

ornamental work etc. It is more costly than OPC

8. Low heat cement: In order to reduce amount of heat, this types of cement is used. This types of cement contains lower % of Tricalcium aluminate (C3A)

and Tricalcium silicate (C3S) and higher % of Diacalcium silicate (C2S)


This cement possesses less compressive strength. The initial setting time is about one hour and final setting time is about

10 hours. It mainly used in mass concrete work.

9. Sulphate resisting cement: To increase a resistance against sulphates, Tricalcium silicate is kept

below 5% to 6%. This cement is used for structure like canal linings, culverts etc. which

are likely to be damaged by alkaline conditions.

Uses of cement: 1. It is used as binding materials with different materials like sand, aggregate

etc.2. It is used in cement mortar for masonry work, plastering work etc.3. It is used to prepare cement concrete for various construction work4. It is used in canal lining, construction of bridges, tunnels etc.5. It is used for making joints for pipes, drains etc.6. It is used in construction of water tanks, wells, precast pipes, watertight

floors Importance of cement:

1. It is an important binding material which binds sand particle to prepare cement mortar and coarse aggregate and fine aggregate to prepare cement concrete.

2. Cement mortar fill the joints of brick and stones3. Cement paste use for smooth plastering work on various components

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