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Bricks

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Rural Technology

Initially, Man lived in natural caves. Then he started using wood, stone and mud to construct his house. He started making wall by placing cut stone on one another. Then he started filling mud to fill he hollow places. During this he might have got idea of making bricks. Wood is mostly used for making roof, doors and windows.

Construction rocks

Rocks are formed from volcanoes. When molten lava gets solidified, some of the constituents form crystal. A stone having small crystals are hard and never breaks straight. Stone with medium size crystals can be cut in straight way in one hammer blow, this is compact basalt type stone.

Mud Bricks

By pressing the mud in a mould, raw mud bricks are made. It is necessary to make proper mixture of sticky clay (less than 0–0.02 mm) and sand (0.0–2mm). If the amount of sticky clay is more, then bricks will develop cracks during drying. Similarly if sand is more, then bricks will become weak. Mud raw bricks are dried slowly in a shade. To make raw mud bricks stronger, grass is mixed in soil and clay is formed. This grass is rotted for 10-15 days in the clay. These bricks strength get reduced to 10kg/cm2 when it becomes wet. In another process, hand machine is used. In this process small amount of water (12% –15%) is used. Mixture of soil and water should not stick to hand but if pressed must become homogeneous. These bricks are dried under shadow for 28 days.

Mud-Cement Bricks

These bricks are made like raw clay bricks. Only difference is 3– 7% (mostly 5%) cement is mixed in the soil before adding water to it. These bricks are stronger than the raw mud bricks.

Burned Bricks

Mud bricks are fired (burned) in kilns. they become light and porous and becomes strong. Unlike raw bricks their strength does not get reduced after putting it in the water. Its size is smaller than raw mud brick for the convenience in firing them in kilns. Country bricks are hand made and table molded bricks are made in steel mould. Burnt bricks are stronger and can be made in variety of shape.

Cement Block

Burnt bricks are becoming more costly due to increasing fuel cost. Therefore, hollow cement block are increasingly used in construction. In this process, cement mortar is pressed in machine mould. The mould is hollow in the center to reduce weight and cost of the brick. These bricks are very strong. They keep the house cool since they are hollow in between and air is bad conductor of heat. They need less material for plaster & less expenses on outdoor colour.

What you have learnt

In this chapter you learnt about different materials used in construction work such as wood, iron, steel , cement and bricks. You also studied their advantages and applications. You learned about types of steels. Now, you also know about how cement got its strength and mortar and concrete is prepared. You also studied types of bricks used in construction.

Terminal Questions

1) Why steel is used in constructing pillars of multi-storied building? 2) What are advantages and disadvantages of wood? 3) Write down different types of steel and their uses? 4) Explain different types of bricks? Why cement blocks are preferred in construction?

Answer to Intext Questions

4.1 i) bad ii) seasoning iii) asphalt and limestone 4.2 i) carbon ii) high carbon steel iii) stainless 4.3 i) compression, weak ii) cement, sand and grovel iii) mortar v) curing

SUGGESTED ACTIVITIES

1. Find out different sizes of bricks available in the market. 2. Study different types of brick work structures used in construction in your town.

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Rural Technology