Properties of Materials MCQ Quiz in मल्याळम - Objective Question with Answer for Properties of Materials - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

Preparation of brick earth

1. Unsoiling

• The soil used for making building bricks should be processed so as to be free of gravel, coarse sand (practical size more than 2 mm), lime and kankar particles, organic matter, etc. About 20 cm of the top layer of the earth, normally containing stones, pebbles, gravel, roots, etc., is removed after clearing the trees and vegetation.

2. Digging

• After removing the top layer of the earth, proportions of additives such as fly ash, sandy loam, rice husk ash, stone dust, etc. should be spread over the plane ground surface on a volume basis. The soil mass is then manually excavated, puddled, watered, and left over for weathering and subsequent processing.

3. Weathering

• The soil is left in heaps and exposed to the weather for at least one month in cases where such weathering is considered necessary for the soil. This is done to develop homogeneity in the mass of soil, particularly if they are from different sources, and also to eliminate the impurities which get oxidized. The plasticity and strength of the clay are improved by exposing the clay to weather.

4. Blending

• The earth is then mixed with sandy-earth and calcareous-earth in suitable proportions to modify the composition of the soil. A moderate amount of water is mixed so as to obtain the right consistency for moulding. 

5. Tempering

• It is done in a pug mill and the process is called pugging. Tempering consists of kneading the earth with feet so as to make the mass stiff and plastics (by plasticity, we mean the property which wet clay has of being permanently deformed without cracking). It should preferably be carried out by storing the soil in a cool place in layers of about 30 cm thickness for not less than 36 hours.

6. Moulding

• It is a process of giving a required shape to the brick from the prepared brick earth. Moulding may be carried out by hand or by machines.

7. Drying

• The object of drying is to remove the moisture to control the shrinkage and save fuel and time during burning.

8. Burning

• The burning of clay may be divided into three main stages: Dehydration stage (400 - 650°C), Oxidation period (650 - 900°C), vitrification. The burning of bricks is done either in clamps or kilns.

Additional Information

Operations involved in the manufacturing of clay brick are:

Explanation

Knotting

• Knotting is a more specific term used in woodworking to describe the process of sealing knots in wood to prevent resin or sap from bleeding through the finish.
• Knotting can be done using various products, and red lead might be one of them. Therefore, "knotting" is a suitable term for covering or killing knots in wood with red lead.

Additional InformationFinishing

• Finishing typically refers to the final steps in the woodworking process, which can include activities like sanding, staining, and applying a protective finish (e.g., varnish or polyurethane) to the wood surface.
• While finishing can help enhance the appearance and protect the wood, it may not specifically refer to the use of red lead to cover knots.

Stopping

• Stopping is not a commonly used term in woodworking to describe the process of covering or killing knots with red lead.
• It is more commonly associated with activities like filling in gaps or imperfections in wood with putty or filler.

Cleaning

• Cleaning is generally associated with removing dirt, debris, or contaminants from a wood surface.

Explanation:

Closer:

A piece of brick which is used to close up the bond at the end of brick courses.
Queen closer:

• Cutting the brick longitudinally in two equal parts.

King closer:

• Cutting a triangular portion of the brick such that half a header and half a stretcher are obtained on the adjoining cut face.

Bevelled closer:

• Cutting a triangular portion of half the width but of full length.

Mitred closer:

• Cutting a triangular portion of the brick through its width an angle of 45° to 60° with the length of the brick.

Half Bat:

• The portion made by cutting the standard brick across their Iength,i.e,quarter bat,half bat, three quarter bat.

Bullnose:

• A brick moulded with a rounded angle.

Cow nose:

• A brick moulded with a double bull nose on end.

Bevelled Bat:

• The portion cut 3/4 of length of brick one side and 1/2 of the length on other side

Explanation:

Field tests for building lime:

IS: 6924-1974, gives a number of field tests for building lime, as follows:
1. Visual examination:

• Class C lime should be pure white in colour.

2. Hydrochloric acid test:

• The purpose of this test is to assess the classification and calcium-carbonate content of lime.

3. Ball test:

• The purpose of this test is to assess the classification.

4. Impurity test:

• The purpose of this test is to assess the quality of lime.

5. Plasticity test:

• The purpose of this test is to assess the plasticity of lime

6. Workability test:

• the purpose of this test is to assess the workability of lime.

Explanation:

According to geological classification, rocks are classified as

1) Igneous rocks:
Ex: Granite, Basalt, Trap, and Dolerite

2) Sedimentary rocks:
Ex: Sandstone, Shale, Slate, Limestone, and Laterite

3) Metamorphic rocks:
Ex: Marble, Quartzite, Slate, and Schist

Additional Information

According to the chemical classification of rocks, they are classified as follows

1) Siliceous rocks:

• The rocks which contain silica as the main constituent is called as siliceous rocks
• Ex: Granite, Gneiss, Trap, Basalt, Sandstone, and Quartzite.

2) Argillaceous rocks:

• The rocks which contain clay or alumina as a main constituent is called as argillaceous rocks.
• Ex: Slate, Laterite, and Kaolin

3) Calcareous rocks:

• The rocks which contain lime or calcium as the main constituent are called calcareous rocks.
• Ex: Marble, Limestone, and Dolomite

Explanation:

Stones are bad conductors of heat. Most of the stones tend to disintegrate when cooling after being heated by fire. Granites disintegrate under fire. Lime stones crumble easily.

Fine-grained sand stones can resist fire moderately. Among all the given options sandstones, especially the compacted type has more fire-resisting properties.

Additional Information:

Characteristics of Sandstone:

• It is a type of rock that has quartz, or sand bound together with cementing minerals like mica, feldspar, etc.
• It is a sedimentary rock.
• Its color depends upon that of the feldspar.
• It can be used as a road metal if higher quality stones like basalt and granite are not available.
• It is fire resistant.
• Its specific gravity is 2.25.
• Its crushing strength varies 35 to 40 MN/m².

Explanation:

Types of lime:

1. Fat lime: It slacks rapidly and its volume is increased by 2 to 2.5 times of its original volume hence, it is referred to as fat lime. It is also known as pure lime, rich lime, high calcium lime. It has more than 95% purity.

Properties- Slow setting, High plasticity, Soluble in water, Vigorous slaking, Perfectly white color

Application- Whitewash & Plasterwork

Source- Seashells

2. Hydraulic lime: It is also known as water lime as it is capable of setting in water and damp condition. It has  70% to 90% purity.

Properties- Insoluble in water, Low plasticity, Less slaking, Off white color, High hydraulicity

Application- Brick masonry or Stonemasonry

Source- Kankar

3. Poor lime: It is also known as Impure or lean lime. It has less than 70% purity.

Properties- Muddy Colour

Concept:

Composition of good brick earth:

1) Silica

• Good brick earth should contain 50 – 60% of silica.
• It prevents cracking, shrinking, and wrapping of raw bricks.
• Silica imparts a uniform shape to the bricks.
• Excess of silica makes the bricks brittle.

2) Alumina

• Good brick earth should contain 20 – 30% of Alumina.
• Alumina imparts plasticity to the earth so that it can be moulded.
• If it is excess raw bricks shrink and warp during drying and burning.

3) Lime

• It should not be greater than 5% for good bricks

4) Iron oxides

• It should be in the range of 5 – 6% for the good bricks.

5) Magnesia

• It imparts colour to the brick.
• It also decreases shrinkage in the bricks.

Explanation:

Ingredient of cement and its effect:

Explanation:

Modular Bricks:

Standard size of brick = 19 cm × 9 cm × 9 cm

Nominal size of a brick with mortar = 20 cm × 10 cm × 10 cm

Non Modular Bricks:

The size of non-modular brick size is 230 × 110 × 70 mm