Concrete Technology and Design

21. According to Whitney's theory, ultimate strain of concrete is assumed to be

1. 0.03 %
2. 0.1 %
3. 0.3 %
4. 3 %

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22. Addition of pozzolana to cement

1. Decreases workability
2. Increases strength
3. Increases heat of hydration
4. None of these

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23. Addition of pozzolana to cement causes

1. Reduction in permeability
2. Loss of heat of hydration
3. Reduction in bleeding
4. All the above

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24. Addition of pozzolana to ordinary port land cement, causes

1. Decrease in early strength
2. Reduction in chemical action with sulphates
3. Increase in shrinkage
4. All the above

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25. Admixtures which cause early setting and hardening of concrete are called

1. Workability admixtures
2. Accelerators
3. Retarders
4. Air entraining agents

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26. After casting, an ordinary cement concrete on drying

1. Expands
2. Mix
3. Shrinks
4. None of these

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27. Air entrainment in the concrete increases

1. Workability
2. Strength
3. The effects of temperature variations
4. The unit weight

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28. Allowable shear strength of concrete, depends upon

1. Shear strength
2. Tensile strength
3. Compressive strength
4. None of these

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29. An aggregate is known as cyclopean aggregate if its size is more than

1. 4.75 mm
2. 30 mm
3. 60 mm
4. 75 mm

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30. An aggregate is said to be flaky if its least dimension is less than

1. 1/5th of mean dimension
2. 2/5th of mean dimension
3. 3/5th of mean dimension
4. 4/5th of mean dimension

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