BUILDING MATERIAL IN CIVIL ENGINERING

'Building material in civil engineering'-Study civil engineering? Building material is the integral part of civil engineering.Learn all about building material subject in civil engineering.

'Building material in civil engineering'

Building materials is materials necessary to build or construct any type of building.some examples of building materials are brick,aggregate,lime,mortar,cement,concrete,etc.

Here are the important information related to these building material -

1.Bricks-

Bricks are the basic thing for any building (residental,educational,etc).there are various size options available in the market.bricks are classified into four types:

1. 1st class bricks(crushing strength=10Mpa)
2. 2nd class bricks(crushing strength=7Mpa)
3. 3rd class bricks(crushing strength=2.5Mpa)
4. 4th class bricks(crushing strength is very low)

The proportions of a ideal bricks are given below-

1. silica(50-60%)
2. alumina(20-30%)
3. lime(10%)
4. magnesia(<1%)
5. ferric oxide (<7%)
6. alkalis (<10%)
7. Co2
8. sulphur trioxide
9. water.

properties of good bricks are-

1. bricks shoould be thoroughly burnt and are of deep red,cherry colour.
2. surface should be smooth and rectangular.
3. metallic sound should come when two bricks are struck against each other.
4. water absorption should be 12-15% of its dry weight.
5. there should have uniform textures.
6. these should be free from flaws,cracks and stones.

2.Aggregate-

Two very important material is conrete and mortar,aggregate plays a vital role in concrete and mortar also.

aggregates mainly of two types.

1. fine aggregate
2. coarse aggregate.

fine aggregate-sand(>0.07mm) is used as fine aggregate in mortar and concrete.it is a granular form of silica.it should be quartz,light grey or whitish variety and should be free from silt.

coarse aggregate-these may be uncrushed  or partially crushed gravel or stonemost of which is retained on 4.75 mm Is sieve.

they should be hard, strong,dense,durable,clear and free from veins.

3.Lime-

hydraulic lime-its is a product obtained by moderate burning of raw limestone which contains small proportion of clay and iron oxide in chemical combination with the calcium oxide content.

fat lime-it s a soft lime obtained by the calcination of nearly pure limestone,marble white chalk,etc

fat lime is nearly pure calcium oxide.

 classification of lime as per BIS-

1. Eminently hydraulic lime
2. semi hydraulic lime
3. fat lime
4. magnesium lime
5. kankar lime
6. siliceous dolomitic lime

Impurities in lime

1. magnesium carbonate
2. clay
3. silica
4. alkalis
5. sulphates
6. iron compounds
7. carbonaceous matters

4.Mortar-

mortar is a mixture of water cement and aggregate.the chief properties of hardened mortar are strength,development of good bond with building units,resistance to weathering.

properties of a good mortar-

1. strength-strength of masonry depends upon both the mortar and the building unit.strong cement mortar are likely to lead shrinkage ,cracks,therefore be avoided except where high strength is required.on the other hand very weak mortar is not suitable also.so selecting the strength as per requirements is also necessary.
2. mobility and place ability-the term mobility is used to indicate the consistency of mortar.place ability is the ease with which mortar mix can be applied with a minimum cost.
3. resistance to penetration of rain-mortar for plastering should protect the masonry joints,building units.
4. water retention-a mortar mix of low water retention will show defects after hardening.water retention is characterised by the ability of mortar not to satisfy during transportation and to retain adequate humidity in a thin layer.

5.Cement-

cement is made of compounds of lime,alumina and silica.in addition most cement contains small properties of iron oxide,magnesia,sulphur trioxide and alkalis.

Roles of oxides in cement-

1. Cao- controls strength and soundness,its deficiency reduces strength and setting time.
2. Sio2-gives strength,excess causes slow setting
3. Al2o3-Quick setting,excess lower the strength.
4. So3-makes cement sound
5. Mgo-imparts colour and hardness.

Different types of cement-

1.rapid hardening cement-It has high lime content and can be obtained by increasing C3S  content.application of this cement is hardening properties and heat emission rather than setting rate.

2.Portland cement-It is a type of cement that improves the workability of concrete,reduce bleeding and segregation  of concrete.

3.ordinary Portland cement-It is mainly used where the slower rate of gaining strength is not important .

Concrete-

concrete-concrete is basically mixture of cement ,water,fine and coarse aggregate.

properties of a good concrete-

1. The strength of concrete can not be less than the specified characteristic strength
2. shrinkage should not occurs after hardening the concrete(contraction of concrete in the absence of load known as shrinkage).
3. durability is also important for concrete.
4. workability of concrete should be as specified in IS CODE.

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