Building Materials

71. The main ingredients of Portland cement are

1. Lime and silica
2. Lime and alumina
3. Silica and alumina
4. Lime and iron

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72. The most common admixture which is used to accelerate the initial set of concrete is

1. Gypsum
2. Calcium chloride
3. Calcium carbonate
4. None of the above

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73. The most commonly used retarder in cement is

1. Gypsum
2. Calcium chloride
3. Calcium carbonate
4. None of the above

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74. The percentage of alumina and silica in good fire clay vary respectively is

1. 25, 75
2. 30, 70
3. 35, 65
4. All of these

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75. The plywood

1. Has good strength along the panel only
2. Can be spilt in the plane of the panel
3. Has greater impact resistance to blows than ordinary wood
4. Cannot be bent more easily than ordinary wood of same thickness

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76. The pressure acting on the stones in stone masonry construction should be

1. Along the direction of bedding planes
2. At 45° to the direction of bedding planes
3. At 60° to the direction of bedding planes
4. Perpendicular to the direction of bedding planes

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77. The proportions of lime and sand in the mortar normally used in brick construction are

1. 1.2
2. 1.4
3. 1.6
4. 1.8

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78. The ratio of the thickness of web to that of flange of steel rolled structural beams and channels is

1. Less than 1
2. Equal to 1
3. Greater than 1
4. Less than 1 in beams but greater than 1 in channels

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79. The rocks which are formed due to cooling of magma at a considerable depth from earth's surface are called

1. Plutonic rocks
2. Hypabyssal rocks
3. Volcanic rocks
4. Igneous rocks

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80. The rocks which are formed due to cooling of magma at a relatively shallow depth from the earth's surface are called

1. Plutonic rocks
2. Hypabyssal rocks
3. Volcanic rocks
4. Igneous rocks

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