**Bangladesh Power Development Board (BPDB)-2018Post: Assistant Engineer (Civil)Venue- BUET**

**1. What is fineness modulus? Calculate the fineness modulus from the following sieve.**

Sieve Size | % Retained |

#4 | 0 |

#8 | 1 |

#16 | 4 |

#30 | 12 |

#40 | 13 |

#50 | 30 |

#100 | 34 |

#200 | 4 |

Pan | 2 |

__Solution:__

The Fineness modulus (FM) is an empirical figure obtained by adding the total percentage of the sample of an aggregate retained on each of a specified series of sieves, and dividing the sum by 100. The sieve sizes are 0.15 mm, 0.3 mm, 0.6 mm, 1.18 mm, 2.36 mm and 4.75 mm.

Sieve Size | % Retained | % Cumulative Retained |

#4 | 0 | – |

#8 | 1 | 1 |

#16 | 4 | 5 |

#30 | 12 | 17 |

#40 | 13 | 30 |

#50 | 30 | 60 |

#100 | 34 | 94 |

#200 | 4 | 98 |

Pan | 2 | 100 |

**2. Determine the volume of cement, sand and stone chips of 10 cft of cement concrete mix with ratio is 1:1.5:3.**

__Solution:__

**3. A rectangular channel width is 20 feet, Manning’s co-efficient 0.021, longitudinal slope 0.0015 and discharge 300 cfs. Find normal depth and velocity.**

__Solution:__

**4. Calculate the angularity number for the aggregate sample from the following data relative density of the aggregate 2.8, mass of water required to fill the cylinder 2500 g, mass of cylinder filled with compacted aggregate 5150 g and mass of cylinder 1100 gm.**

__Solution:__

**5. Flow diagram of essential elements of water supply system.**

Solution:

**6. Flow diagram of conventional activated sludge process.**

Solution:

**7. The amount of BOD _{5} in a sewage found 200 mg/L at temperature 20^{o}C. If k = 0.22/day, then determine the BOD_{10} at the same temperature.**

__Solution:__

**8. Define BOD and COD. Why COD is greater than BOD?**

Solution:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized.

COD measures all organic compounds that can be chemically oxidized. On the other hand BOD measures the dissolved oxygen consumed by organisms to oxidize organic compounds. In other words, BOD measures only the organic compounds that can be consumed by organisms while COD measures all. Hence, COD should always be higher than BOD.

**9. Draw Marshal Mix design curves.**

Solution:

**10. A retaining wall is 6 m height. Uniform load acting on the wall is 6 KN/m ^{2}. Non cohesive soil backfill, = 18 KN/m^{3}, = 30^{0}, water table 2 m from top. Find out the resultant active force per unit length.**

__Solution: __

**11. A sand layer having properties, = 16 KN/m ^{3}, = 18 KN/m^{3}, Gs = 2.6, = 36^{0}. Water table is 2.4 m below the ground level. Determine shear strength at a depth of 5 m from its base.**

__Solution:__

**12.Determine the ultimate moment capacity of the T beam f’c=3 ksi and fy=40 ksi**

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AUTHOR**Engr.Abu Jobair**

Assistant Engineer (Civil)

Bangladesh Water Development Board

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