Civil engineers build the world’s infrastructure. In doing so, they quietly shape the history of nations around the world. Most people can not imagine life without the many contributions of civil engineers to the public’s health, safety and standard of living. Only by exploring civil engineering’s influence in shaping the world we know today, can we creatively envision the progress of our tomorrows.
1,What are the chemical analysis for soil?
A:GRADE = CEMENT : SAND : aggregate
M7.5 = 1 :4 :8
M10 =1 :3 :6
M15 =1 :2 :4
M20 =1 :1.5 :3
M25 =1 :1 :2
3. Transporting and placing of concrete
> Batching: The process of measurement of the different materials for the making of concrete is known as batching. batching is usually done in two ways: volume batching and weight batching. In case of volume batching the measurement is done in the form of volume whereas in the case of weight batching it is done by the weight.
> Mixing: In order to create good concrete the mixing of the materials should be first done in dry condition and after it wet condition. The two general methods of mixing are: hand mixing and machine mixing.
> Transportation and placing of concrete: Once the concrete mixture is created it must be transported to its final location. The concrete is placed on form works and should always be dropped on its final location as closely as possible.
> Compaction of concrete: When concrete is placed it can have air bubbles entrapped in it which can lead to the reduction of the strength by 30%. In order to reduce the air bubbles the process of compaction is performed. Compaction is generally performed in two ways: by hand or by the use of vibrators.
21,Describe briefly the various methods of concrete curing.
(a) Spraying of water: on walls, and columns can be cured by sprinkling water.
(b) Wet covering of surface: can be cured by using the surface with wet gunny bags or straw
(c) Ponding: the horizontal surfaces including the slab and floors can be cured by stagnating the water.
(d) Steam curing: of pre-fabricated concrete units steam can be cured by passing it over the units that are under closed chambers. It allows faster curing process and results in faster recovery.
(e) Application of curing compounds: compounds having calcium chloride can be applied on curing surface. This keeps the surface wet for a very long time.
22,What do you understand by “preset” during the installation process of bridge bearings?
> Length of bearing
> 2 x irreversible movement.
> 2 x reversible movement.
The bearing initially is placed right in the middle point of the upper bearing plate. No directional effects of irreversible movement is considered. But since the irreversible movement usually takes place in one direction only the displaced direction is placed away from the midpoint. In such cases the length of the upper plate is equal to the length of the length of the bearing + irreversible movement + 2 x reversible movement.
> Spalling Reinforcement: The spalling stresses leads to stress behind the loaded area of the anchor blocks. This results in the breaking off of the surface concrete. The most likely causes of such types of stresses are Poisson`s effects strain interoperability or by the stress trajectory shapes.
> Equilibrium reinforcements: This type of reinforcements are required where several anchorages exist where the prestressing loads are applied in a sequential manner.
> Bursting Reinforcements: These kinds of stresses occur in cases where the stress trajectories are concave towards the line of action of load. In order to reduce such stresses reinforcements in the form of bursting is required.
25,How to close the Tie rod penetratin? What material shall be provide? why it provided ?
3,What is the relation between seventh day strength & twenty eighth day strength of cement concrete ?
6. In the design of bridge arguments what considerations should be made to select the orientation of the wing walls?
> Wing walls parallel to abutments: This method is considered to take least amount of time to build and is simple as well. But on the downside this method is not the most economical. The advantage of this type of design being that they cause the least amount of disturbance to the slope embankment.
> Wing walls at an angle to abutments: This design method is considered to be the most economical in terms of material cost.
> Wing walls perpendicular to abutments: The characteristic of this design is it provides an alignment continuous with the bridge decks lending a support to the parapets.
7. In case if concrete box girder bridges how is the number of cells determined?
8. Under what circumstances should pot bearings be used instead of elastomeric bearings?
9. Why should pumping be not used in case of concreting works?
10. Why should curing not be done by ponding and polythene sheets?
11. What are the different type of slump test indications?
> True Slump
> Shear Slump
> Collapse Slump
True Slump: This type of slump is characterized by the general drop of the concrete mass evenly without visible signs of deterioration or disintegration.
Shear Slump: It indicates that the concrete mix is deficient in cohesion. This type of slump leads to segregation and bleeding. Henceforth in the long run effecting the durability of the concrete.
Collapse Slump: This type of slump is indicates that the mix of concrete is simply too wet. The mix is considered to be harsh and lean.
12. Why is propping required for long structures once the formwork is removed?
13. Explain the mechanism of cavitations in pipes and drains?
14. For what purpose bedding is used under storm water drains, explain?
> They are used to provide a more uniform support for the under pipes so that the bending moment longitudinally can be reduced greatly.
> In order to enable the pipes to get more load-supporting strength.
> They are also used to act as a platform to achieve a more correct alignment and level pre and post construction.
> In case of pipes which contain spigot and socket joints, it enables pipes to get supported along pipe lengths in place of sockets. Otherwise it can lead to uneven stress being induced on the pipes eventually damaging it.
15. Why are pull-out tests performed for soil nails?
> In order to detect and the verification of the bond strength among the soil and the grout adopted during the design of soil nails. This is considered to be as the primary objective of performing pull out tests for soil nails.
> For the detection of any slippage or occurrence of creeps.
> To detect the elastic and deformations (plastic) of any of the test nails employed. Observations are made during the loading and unloading cycles of the soil nails repetitively.
> To achieve the perfect balance the test nails should always be loaded so that the ultimate soil/grout mixture with an upper limit of 80%.
16. Describe briefly the advantages and disadvantages of using plastic and timber fenders?
Plastic fenders are low in strength with a relatively high resistance to abrasion. Plastic fenders are resistant to chemical and biological attacks. Plastic fenders have moderate energy absorption capacity. The berthing reactions are also comparatively moderate and depends on the point of contact. Also since they are made from recycled material they are environmental friendly.
The advantages and disadvantages of using timber fenders are:
timber fenders are low in strength and are very susceptible to marine borer attacks and rotting. The energy absorption capacity is very low. Also generally the contact pressure between the vessels and the fender are high.
17. Explain why concrete barriers have curved surface profiles?
18. Why is the use of granular sub-base in concrete carriageways not preferred, explain?
> Sub bases are permeable and hence water can seep through them easily. The soil particles get pumped out through the joints on the application of traffic loads. This results in the creation of voids underneath the pavement structure. This leads to the weakening of the concrete surface and it can crack easily upon intense traffic loads.
> Instead if lean concrete is used for carriageways it greatly increases the strength of the roads and the load carrying capacity of the roads is increased.
> Sub-bases implementation requires a lot of workmanship which can lead to an un-uniform distribution of the sub-base. This can lead to the cracking of the carriageway when there is severe traffic loading.
19. Why are separation membranes used between concrete pavement slab and sub-base?
> The separation membrane reduces the frictional forces between the concrete slabs and the sub-base. The membrane aids the movement of the concrete slab in reference to the sub-base when changes in the level of the moisture and temperature occurs.
> It aids in the segregation of sub-base materials from freshly placed concrete.
> The separation membrane also helps in the reduction of cement and water loss in the form of immature concrete. Immature concrete greatly affects the strength of the concrete. It also affects the durability of it.
A good example of a separation membranes is polythene sheeting which is commonly used.
20. In the roof of a pumping station explain briefly the components of a waterproofing system.
> Right above the structural finish level of the roof ( concrete ) a uniform thickness screed is applied so as to facilitate the application of the waterproofing membrane. The surface provide for the membrane should always possess good cohesion properties and must be thin so as to prevent any un-uniformity. This thin layer also acts as a layer of thermal insulation.
> Right above this layer the waterproofing membrane is deployed to secure the water tightness of the roof.
> In order to enhance the thermal insulation of the roof an insulation board is sometime placed right above the waterproof membrane. The insulation board helps in the maintenance of a stable temperature in both weathers.
21. During reclamation how can the occurrence of mud waves can be rectified?
> Complete removal of all the disturbed mud: This method can be considered to be one of the fastest methods. As soon as the disturbed mud is removed some filling material is used to replace the disturbed mud. But economically this method can be expensive as compared to others.
> Accelerated consolidation of disturbed mud: In this method surcharging loads are placed on top of the mud waves. Along with this band drains are installed to accelerate the consolidation process. This method is quite slow compared to the other methods.
> Partial removal of the disturbed mud: This method is the hybrid of the above two methods where the top layer is removed whereas the lower level is treated with the surcharging process.
22. In reclamation works what are the importance of geotextiles and sand?
> Geotextiles: They are used to separate the marine mud from the reclamation fill. Also geotextiles are used as reinforcements in reclamation processes to increase its stability. It is still debated as to whether the usage of geotextiles is better or are the old processes followed are better as the performance has not been comparable to the conventional methods.
> Sand: In reclamation process sand is used to spread the load of any future public dumps placed on top of it. Sand also acts as a drainage for the excess pore water pressure of band drain installations.
23. In block work seawalls what is the purpose of slip joints?
24. For a washout valve why are two gate valves required in normal practice?
25. What are the different approaches in designing the floors of the service reservoirs?
> In this approach the movement joints of the reservoir floor panels are such that the free expansion and contraction of the panels takes place. Every panel is isolated from the other panels and two panels have a sliding layer between them to help in sliding.
> The second method does not provide any room for free movement. With seasonal and shrinkage movements, some cracks are designed to voluntarily occur on the floors of the service reservoirs. These tiny cracks are spread throughout the floor and are simply too minute to cause any leakage or corrosion of the floors. But the difference also in this method is that the amount of reinforcement used is much more than the first approach.
2. What is modular elasticity?
3. Discuss some applications of modular elasticity.
4. What is difference between engineering stress and true stress?
5. What are some structures that are subjected to fatigue?
6. What is the tensile strength of wood?
7. Explain soil analysis?
8. What is soil enforcement?
9. How can you achieve soil enforcement?
10. What is a bearing capacity of soil?
11. Why does the pressure increase under soil?
12. How to increase a bearing capacity of soil?
13. What you understand by building codes?
14. Explain moment of inertia and its importance.
15. Which is the best book for building construction?
16. How do we determine the specific gravity of a cement?
17. What are the causes of building collapse?
18. Explain the latest method to detect a crack in a building?
19. How do we test on design and style in a software?
20. Explain different types of RCC pipes.
21. Explain the design for RCC multi-storied building?
22. What are the benefits of RCC pipes over steel designed pipes?
23. Elaborate advantages & disadvantages of using crusher dust instead of sand in RCC work.
24. How can you produce desired alloys and discuss their applications in daily life.
25. Can inverted beams used in pipes during construction? If yes, explain how it can be implemented?
26. What is rigging?
27. What are the techniques to measure road difference?
28. Explain major differences between routing maintenance and major maintenance.
29. What you understand by Richter scale?
30. How do we calculate the power of centrifugal pump?
31. What is a tensile strength? What is the tensile strength of wood?
32. Difference between pre-tensioning and post-tensioning.
33. Explain the difference between shear and tensile strength.
34. Why the statue of liberty is made of Copper?
35. What is the difference between TOR steel and TMT steel?
36. Which code is used for TOR & TMT steel bar?
37. Explain major difference between auto level and dumpy level?
38. What is the L/D ratio of cantilever beam?
39. What is the ratio of steel and concrete to use in slabs , beams, columns ?
40. What is pre-stressed concrete?
41. What are the ingredients of pre-stressed concrete?
42. What do you mean by honeycomb in concrete?
43. Why is concrete cube test carried out?
44. How do you calculate the power of centrifugal pump?
45. What is aggregate?
46. What is absolute pressure? How absolute pressure is calculated?
47. What is the absolute pressure scale?
48. What is gravity flow?
49. What is a projection line?
50. What is horizon or horizontal mining?
Prepared by M.Ajmal Khan.