Power Grid Company of Bangladesh (PGCB)
Post: Assistant Engineer (Civil)
Date: 2017
Exam Taker-MIST
1. Show typical cantilever beam reinforcement detailing.
Solution:
2. Difference between initial setting time and final setting time.
Solution:
The time between the water is added to cement till it starts losing its plasticity is called as initial setting time. The time between which water added to cement till it has come in hardened state is called as final setting time. Initial setting time of ordinary Portland cement should not be less than 30 min and final setting time should not be more than 10 hrs.
3. Short column and long column failure pattern.
Solution:
4. Why aeration is necessary in waste treatment process?
Solution:
Wastewater aeration is the process of adding air into wastewater to allow aerobic bio-degradation of the pollutant components. In municipal and industrial wastewater treatment, aeration is part of the stage known as the secondary treatment process. The activated sludge process is the most common option in secondary treatment. Aeration is an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. The microbes feed on the organic material, forming flocs which can easily settle out. After settling in a separate settling tank, bacteria forming the “activated sludge” flocs are continually re-circulated back to the aeration basin to increase the rate of decomposition. An ample and evenly distributed oxygen supply in an aeration system is the key to rapid, economically viable and effective wastewater treatment.
5. If a 2% solution of sewage is incubated for 5 days at 20oC and dissolved oxygen depletion was 5 ppm, determine BOD5.
Solution:
6. Difference between flyover and interchange.
Solution:
Flyover: Flyover is a grade separation whereby traffic moves separately without the provision of interchange between them.
Interchange: Interchange is a grade separation with inter connecting facilities of two or more road way at different level.
7. How SPT N counts in field?
Solution:
The test uses a thick-walled sample tube, with an outside diameter of 50.8 mm and an inside diameter of 35 mm, and a length of around 650 mm. This is driven into the ground at the bottom of a borehole by blows from a slide hammer with a mass of 63.5 kg (140 lb) falling through a distance of 760 mm (30 in). The sample tube is driven 150 mm into the ground and then the number of blows needed for the tube to penetrate each 150 mm (6 in) up to a depth of 450 mm (18 in) is recorded. The sum of the number of blows required for the second and third 6 in. of penetration is termed the “standard penetration resistance” or the “N-value”. In cases where 50 blows are insufficient to advance it through a 150 mm (6 in) interval the penetration after 50 blows is recorded. The blow count provides an indication of the density of the ground, and it is used in many empirical geotechnical engineering formulae.
8. Saturated soil, w = 30%, G = 2.65, determine dry unit weight.
Solution:
9. What are the methods of grading asphalt?
Solution:
Four methods of grading of asphalt:
- Performance grading
- Penetration grading
- Viscosity grading
- Viscosity of aged residue grading
10. What are the forces acting on gravity dam?
Solution:
In the design of a dam, the first step is the determination of various forces which acts on the structure and study their nature. Depending upon the situation, the dam is subjected to the following forces:
- Water pressure
- Earthquake forces
- Silt pressure
- Wave pressure
- Ice pressure
- Uplift pressure
- The stabilizing force is the weight of the dam itself.
11. If e = 0.10 and f = 0.15, design speed = 100 kmph, determine radius of curvature.
Solution:
12. Difference between compaction and consolidation.
Solution:
| Compaction | Consolidation |
| Compaction is a process where a mechanical pressure is used to compress the soil mass for the purpose of soil improvement. | Consolidation is a process where steady and static pressure causes compression of saturated soil. |
| Dynamic loads by rapid mechanical methods like tamping, rolling and vibration are applied for a small interval in soil compaction. | Static and sustained loading is applied for a long interval in soil consolidation. |
| Compaction of soil is mainly used for sandy soil. | C Consolidation of soil is mainly used for clayey soil. |
| In compaction process, soil volume is reduced by removing air void from the saturated and dry soil. | Consolidation is due to expulsion of pore water from voids. |
| Compaction is done before the construction of structure. | The process of consolidation starts as soon as the construction work begins. |
13. If a partially saturated soil becomes fully saturated soil due to change in water table, then how it affects void ratio of soil?
Solution:
Void ratio will not change.
For partially saturated soil Vv = Va + Vw, when it will be fully saturated, volume of air will be covered by water Vv = Vw.
Download PDF-PGCB Assistant Engineer (Civil) 2017 full Question Solution from below link
Author:
Engr. Abu Jobair
Assistant Engineer (Civil),Bangladesh Water Development Board
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