BUILDING LIME | BUILDING MATERIAL | CIVIL ENGINEERING PSC

LIME

Lime is one of the basic building material used mainly as lime mortar in construction. Lime has been used as a cementing material since the ancient times in India and abroad. Even in India, various engineering structures like palaces, bridges, temples etc were constructed with lime mortar and still are in shape. 

After the invention of cement in 1824 lime has been replaced by the cement to a large extent, however it is still used at certain places, like for the repairing of the structures which were originally built with the lime mortar. The broad category of lime is non-hydraulic and hydraulic lime.

The non-hydraulic lime is called as quick lime, fat lime or white lime or as lump lime. Hydraulic lime sets under water and non-hydraulic lime do not set under water.

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MANUFACTURING OF LIME MORTAR

CLASSIFICATION OF LIME:

Broadly lime is classified into three categories:

(1) Fat Lime   (2) Hydraulic lime  (3) Poor Lime

(1) Fat Lime/Pure Lime /Slaked/High Calcium or Non-Hydraulic Lime:-  Fat lime is also known as pure lime, white lime or rich lime, this is manufactured using the purest form of the limestone. It is popular with its name as fat lime since its volume is increased to about 2 to 2.5 times its originally volume after getting slaked. It slakes vigorously.

(2) Hydraulic Lime: This lime has the hydraulic property, means it can set under the water also. It contains clay and some amount of ferrous oxide also. This is also known as water lime.Depending upon the amount of clay hydraulic lime is classified into further three categories:

(a) Feebly hydraulic lime

(b) Moderately hydraulic lime

(c) Eminently hydraulic lime

Increase in the percentage of clay makes the slaking difficult and thus increases the hydraulic property of lime. With about 30 per cent of clay lime resembles the color of cement.

The color of fat lime is not white therefore fat lime looks more sanitary than the hydraulic lime.

(3) Poor Lime: Poor lime contains more than 30 percent of clay therefore it is also known as impure lime. It slakes very slowly and also does not dissolve into water. It has poor binding property and its color is muddy white.

This lime forms very poor mortar and so such lime can be used for inferior types of work or at places where good lime is not available.

BIS: 712 - 1984 classification

lime under six categories, namely Class A, Class B, Class C, Class D, Class E and Class F.

Class A

lime is used for structural purposes because it is eminently hydraulic lime and has the property of setting even in the absence of air. It has to be supplies in the hydraulic form only. Its minimum strength with lime sand mortar of proportion(1:3) by weight at the end of 14 days and 28 days should be respectively 1.75 N/mm2  and 2.80 N/mm2.

Class B

lime is the semi-hydraulic lime which is used for mortars for masonry and it can be supplied either as quick lime or as hydrated lime. Its minimum compressive strength with lime sand mortar of proportion(1:3) by weight at the end of 14 days and 28 days should be respectively 1.25 N/mm2 and 1.75 N/mm2.

Class C

lime is the fat lime which is used mainly for finishing coat in plastering, whitewashing and with suitable admixture such as surkhi or any other pozzolanic material to produce artificial hydraulic mortars. It is to be supplied in hydraulic or quick form.

Class D

lime is the magnesium or dolomitic lime which is used for finishing coat in plastering, whitewashing, etc. It is to be supplied in the hydrated or quick form.

 

Class E 

lime is the kankar lime and is used for the masonry works. It is produced by burning lime nodules which are seen in soils like black cotton soil containing silica in the hydrated form.

Class F  

lime is also known as Siliceous dolomitic lime which is used for undercoat and finishing coat of plaster. It is to be supplied in the hydrated or quick form.

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CEMENT | BUILDING MATERIAL| CIVIL ENGINEERING PSC

BUILDING MATERIALS

• CEMENT

         

                   
                     A cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is only behind water as the planet's most-consumed resource.

Cements used in construction are usually inorganic, often lime or calcium silicate based, which can be characterized as non-hydraulic or hydraulic respectively, depending on the ability of the cement to set in the presence of water.

Non-hydraulic cement does not set in wet conditions or under water. Rather, it sets as it dries and reacts with carbon dioxide in the air. It is resistant to attack by chemicals after setting.

Hydraulic cements (e.g., Portland cement) set and become adhesive due to a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble and so are quite durable in water and safe from chemical attack. This allows setting in wet conditions or under water and further protects the hardened material from chemical attack. The chemical process for hydraulic cement was found by ancient Romans who used volcanic ash (pozzolana) with added lime (calcium oxide).

cement full details

include

    1. introduction

    2. Types of cement

    3. Tests for cement

    4. raw materials of cement

    5. manufacturing of cement

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The first part of video include Raw materials for cement and their properties 

The second part include process of manufacturing of cement

The third part include properties of cement 

ie 's 

• physical properties
• chemical properties

The fourth part include test to be done for finding properties of the cement..

two properties

1. field test
2. lab test

The fifth part of cement include types of cement and their properties

13 types cement available

Previous kerala psc question are available 

cement part 1

   

1. The main constituents of cement is  ***

a)Lime

b)Silica

c)Alumina

d)calcium sulphate

 ans a) lime

2 ) The ingredient that imparts quick setting property to cement is  *

a)Alumina

b)Silica

c)Gypsum

d)Lime

    ans:  a) Alumina

3. A good quality cement should have higher percentage of

a)Silica

b)Free lime

c)Di calcium silicate

d)Tri calcium silicate

    ans : d) Tri calcium silicate

4) The cementing property in cement in mainly due to

a)Silica

b)Lime

c)Iron oxide

d)Alumina

Ans: b) lime

5) The silica in portland cement should be

a)20 to 25%

b)10 to 20%

c)25 to 40%

d)40 to 60%

Ans: a) 20 to 25%

6) Silica is melt at ………… oC.

a) 1730 oC.

b) 1400 oC

c) 1430 oC

d) 1510 oC

Ans: a) 1730 oC

7) Alumina is :

a)Al2O3

b)Al2SO4

c)Al2O3SiO3

d)Al2K2SO4       

Ans: a) Al2O3

8) Cement contains ………% of lime.

a)55

b)3

c)62

d)75

Ans: c) 62

9) The function of gypsum in cement is :

a)To increase strength

b)To increase initial setting time

c)To decrease initial setting time

d)To increase final setting time

   ans: b)  To increase initial setting time

10) Which of the following is an ingredient present both in cement and brick.

a)Iron oxide

b)Magnesium

c)Alumina

d)Alkalies

Ans : c) Alumina

11) The chemical constituents of silica in portland cement is ….

a)15 to 20%

b)17 to 20%

c)17 to 25%

d) 15 to 25%

Ans : c) 17 to 25%

12)The major ingredient of portland cement are..

a)Lime 62% and silica 22%

b)Lime 68% and silica 32%

c)Silica and alumina

d)Lime and iron

Ans: a) lime 62% and silica 22%

13) Total water soluble sulphate content of the concrete mix, expressed as SO3 ,by the mass of cement should not exceed:

a)3%

b)4%

c)5%

d)6%

  Ans: b)4%

14) Chemical formula of dicalcium silicate

a) 2CaOSiO3

b) 2CaOSio2

c) CaOSiO2

d) 2CaOSiO4

Ans : a) 2CaOSiO3  

15) The compound formed within about 24 hours after the addition of water to cement is

a)Tricalcium aluminate

b)Dicalcium aluminate

c)Dicalcium silicate

d)Tricalcium silicate

Ans: a) Tricalcium aluminate