Concrete Technology and Design

91. For the design of retaining walls, the minimum factor of safety against overturning is taken as

1. 1.5
2. 2
3. 2.5
4. 3

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92. For walls, columns and vertical faces of all structural members, the form work is generally removed after

1. 24 to 48 hours
2. 3 days
3. 7 days
4. 14 days

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93. Grading of sand causes great variation in

1. Workability of concrete
2. Strength of concrete
3. Durability of concrete
4. All the above

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94. Gypsum is added for

1. Colour
2. Strength
3. Controlling setting time
4. None of these

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95. Half of the main steal in a simply supported slab is bent up near the support at a distance of 'x' from the center of slab bearing where 'x' is equal to (Where 'l'is the span)

1. l/3
2. l/5
3. l/7
4. l/10

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96. Hardening of cement occurs at

1. Rapid rate during the first few days and afterwards it continues to increase at a decreased rate
2. Slow rate during the first few days and afterwards it continues to increase at a rapid rate
3. Uniform rate throughout its age
4. None of these

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97. High carbon content in the steel causes

1. Decrease in tensile strength but increase in ductility
2. Increase in tensile strength but decrease in ductility
3. Decrease in both tensile strength and ductility
4. Increase in both tensile strength and ductility

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98. High temperature

1. Increases the strength of concrete
2. Decreases the strength of concrete
3. Has no effect on the strength of concrete
4. None of these

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99. Higher workability of concrete is required if the structure is

1. Made with cement concrete
2. Thick and reinforced
3. Thin and heavily reinforced
4. Thick and heavily reinforced

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100. Horizontal construction joints in concrete walls are generally provided at

1. Soffit level
2. Window sill level
3. Floor level
4. All the above

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