Two Marks Questions and Answers

TWO MARKS QUESTIONS AND ANSWERS

1. Classify the types of stones.     

Stones are classified based on the following categories:

❖ Geological

* Igneous

* Sedimentary

* Metamorphic

 ❖ Physical

* Stratified

* Un-stratified

* Foliated

❖ Chemical

* Argillaceous

* Silicious

* Calcaracious

2. Write the any characteristics of good building stones.

(i) Structure

❖ Structure of a stone layer may be either stratified or unstratified.

❖ Structured stones are easily dressed and are suitable for the superstructures.

❖ Unstratified stones are hard and difficult to dress and are preferred for the foundation works.

(ii) Texture:

❖ Fine grained stones are usually strong and durable.

❖ For carving, attractive fine-grained stones with homogeneous distribution are used.

(iii) Density:

❖ Light weight stones are weak and denser stones are stronger.

❖ Stones with specific gravity less than 2.4 are not suitable for buildings.

(iv) Appearance:

❖ Appearance is a chief requirement for the selection of the stone.

❖A stone with uniform and attractive colour is durable, if grains are compact.

❖The colour and ability to receive polish greatly influence the appearance.

❖Marble and granite get very good appearance, when polished. Hence they are used for face works in buildings.

3. List the tests conducted on stone.

Following are different tests on conducted on building stones:

❖ Water absorption test

❖ Crushing strength test

❖ Impact test

❖ Abrasion test

❖ Acid test

4. What are the uses of stones?

General uses of building stones are:

❖ Construction of foundations, walls, columns and arches are done using stone masonry.

❖ Stone slabs are used for flooring, damp proof courses, lintels and even as roofing materials.

❖ Polished granite and marbles are commonly used for facing and flooring works.

❖ Road pavements and footpaths are also made using stones.

❖ Constructions of piers and abutments of bridges, dams and retaining walls are also done suing stones.

❖ Crushed stones are used as base course for roads, inert material in concrete and as railway ballast.

5. What are the commonly used stones in India?

Commonly used stones in our country are:

❖ Marble

❖ Granite

❖ Sand stone

❖ Basalt

❖ Slate

❖ Limestone

❖ Gneiss

❖ Gneiss

❖ Laterite

6. Classify bricks based on their quality.

Bricks are classified into four categories based on their quality as given below:

❖  First class bricks

❖ Second class bricks

❖ Third class bricks

❖  Fourth class (Over burnt) bricks zonote

7. Classify bricks based on their constituent materials.

Based on the constituent materials used, bricks are classified as follows:

❖ Common Burnt Clay Bricks

❖ Sand Lime Bricks

 ❖ Engineering Bricks

❖ Concrete Bricks

❖ Fly Ash Clay Bricks

8. Classify bricks based on their utility.

Based on their usage, bricks are classified as follows:

❖ Building Bricks

❖ Paving Brick

❖ Fire Bricks

❖ Special Bricks

9. List the process involved in the manufacturing of bricks.

The following operations are involved in the process of manufacturing bricks:

❖ Preparation of clay

❖ Moulding

❖  Drying

❖ Burning

10. Write about refractory bricks. Where are they commonly used?

Refractory brick is a block of refractory ceramics material used in lining furnaces, kilns & Fireboxes. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency.

11. Define the term Efflorescence.

Efflorescence is defined as the presence of grey or white layer on brick surface by absorbing moisture. It is formed due to the presence of alkalies in bricks. In the efflorescence test, if the presence of alkalies is over 50% then the brick is severely affected by alkalies. Hence more deposits will be visible over the brick surface.

12. How do you calculate water absorption of brick?

In water absorption test brick specimens are weighed in dry condition and are immersed in fresh water for 24 hours. After 24 hours of immersion, specimens are taken out from water and wipe out with cloth. The weight of each specimen in wet condition is noted. The difference in weights is the water absorbed by brick. The percentage of water absorption is then calculated by the ratio of water absorbed to dry weight multiplied by 100. Average of five specimens is taken as the water absorption. Good quality brick doesn't absorb more than 20% water of its own weight.

13. How do you conduct hardness test on brick?

Hardness test is a field test, in which a scratch is made on brick surface with a nail. If that doesn't left any impression on brick then that is good quality brick.

14. Differentiate between first class and second class bricks.

S. No

First class bricks

First class bricks are table moulded and of standard shape.

Its surface is smooth, clean and free from cracks.

Minimum crushing strength is 10.5N/mm²

Second class bricks

Second class bricks are ground moulded and irregular in shape. 

 Its surface is rough and it is not free from  lumos and cracks

Minimum crushing strength is 7 N/mm²

15. What are the uses of bricks?

Bricks are commonly used for the following civil works:

❖ For masonry works and construction of arches, cornices.

❖As brick jelly aggregates in PCC and waterproofing works.

❖ For pathways as pavers and construction of temporary structures.

❖For sewer lining, chimney and furnace linings.

❖As a fire protective coat for steel columns.

16. Define "slaking of lime".com

Slaking of lime is the process, which is the chemical combination of quick lime with water. It has got the tendency of absorbing carbonic acid from the atmosphere in presence of water. It is ordinary pure lime, in white powder form, available in market. Slacked lime is also known as hydrated lime.

17. What is Quick lime?

Quick lime is obtained by calcination (i.e. heating to redness) of comparatively pure lime stone. It is the cheapest form of lime and is also known as caustic lime. It is amorphous in nature, highly caustic and possesses great affinity to moisture. It is the main ingredient in the manufacturing of cement.

 18. What do you mean by Fat lime?

Fat lime is also known as high calcium lime or pure lime. Sometimes it is called as rich lime or white lime as it is white in colour. It is popularly known as fat lime as it slakes vigorously and its volume is increased to about 2 to 2.5 times that of quick lime. It is composed of 95% of calcium oxide. It hardens slowly and has high degree of plasticity. This lime is used for various purposes as white washing, plastering of walls, as lime mortar with sand for pointing in masonry works.

19. List the tests conducted on lime.

To determine their suitability, the following tests are conducted on lime:

❖ Physical Test

❖Chemical Test

❖ Heat Test

❖ Ball Test

20. What are the uses of lime?

The following are the uses of limestone in construction works:

❖ For white washing works

❖ For production of lime sand bricks.

❖For preparing lime mortar for plastering and masonry works.

❖For manufacturing cement

❖ For lining in open hearth furnaces.

❖ For soil stabilization.

21. Write about hollow concrete blocks.

Hollow concrete blocks are manufactured with lean mixes of cement, sand and aggregates of sizes less than 12 mm. Instead of sharp edged aggregates, round aggregates are used in the manufacture of these blocks. As per the recommendations of the IS 2185 (Part-1) 2005, the total void area shall range from 50% to 75% of the gross cross-sectional area. These holes or cavities reduce the total cross-sectional area of the block and hence the weight of block structure as a whole.

22. What are the advantages of hollow concrete blocks?

Hollow concrete block masonry has the following advantages:

❖ Hollow concrete block masonry reduces the cost of labour and materials, since larger size blocks reduces the number of joints in masonry work.

❖ It is a faster and easier construction practice, when compared to the Em conventional masonry systems.

❖ The hollow concrete blocks are light in weight, so they reduce the weight of the structure and hence light structural member or minimum percentage of steel is required for R.C.C building.

❖ Hollow concrete block masonry is highly durable as it is compacted by high pressure and vibration, which gives substantial strength to the block. Adequate curing increases the compressive strength of the blocks.

23. List the uses of Hollow Concrete Blocks.

Hollow concrete blocks are used in all type of masonry construction such as,

❖ Exterior and Interior load-bearing walls

❖ Fire-safe walls around stairwells, elevators

❖ Fire walls and curtain walls

❖ Partition wall and panel walls

❖ Piers, column and retaining walls

❖ Backing for brick, stone, and other facing works

❖ Boundary fences

24. What is a lime mortar?

Lime mortar is formed by mixing of lime, sand, and water. The required amount of lime and sand is placed on the ground or tray. The lime and sand are mixed evenly by turning the spades up and down. The water is added till the uniform color and consistency of the mortar area unit is obtained and also the mixture is persistent with spades.

25. What is a light weight concrete block?

A lightweight concrete block is a concrete masonry unit made of expanded aggregate to reduce the density and weight compared to standard concrete block. These blocks are produced in greater volume but are less strong than other concrete blocks. They can be used in both internal and external walls where loading is slightly limited.