Civil Engineering Interview Questions and Answers

The most important part of preparing for an interview for a job is to be aware of what kind of civil engineering interview questions might be thrown in your direction. That way, you will be in a great position to prepare your answer well in advance and feel confident that your responses will impress the interviewer.

Here is a list of must-known civil engineering interview questions and answers to ensure your next interview is a success.

Question: What is the Unit Weight of concrete?

Answer: The unit weight of concrete depends on the type of aggregates and the number of voids. As per IS:456:2000 Unit weight of Plain Cement Concrete is 2400 Kg/m3 and Reinforced Cement Concrete is 2500 Kg/m3.

Question: What are the various steps involved in the concreting process?

Answer:

Batching

Mixing

Transportation and Placing of concrete

Compaction of concrete

Question: What are the Nominal Concrete Mix Proportions for different grades of concrete?

Answer:

M25 – 1:1:2

M20 – 1:1.5:3

M15 – 1:2:4

M10 – 1:3:6

Question: What is the unit weight of steel?

Answer: The unit weight of steel is 7850 Kg/m3.    

Question: Describe briefly the various methods of concrete curing?

Answer: Curing is the process of maintaining the moisture & temperature conditions for freshly deployed concrete. This is done for a small duration of time to allow the hardening of concrete.

The various methods of concrete curing are as below:

  • Spraying of water: on walls and columns can be cured by sprinkling water.
  • The wet covering of surface: can be cured by using the surface with wet gunny bags/straw.
  • Ponding: the horizontal surfaces including the slab floors can be cured by stagnating the water.
  • Steam curing: of pre-fabricated concrete units steam can be cured by passing it over the units that are under the closed chamber. It allows faster curing processes and results in faster recovery.
  • Application of curing compound: compounds having calcium chloride can be applied to the curing surface. The curing compound keeps the surface wet for a very long time.

Question: What is ductility?

Answer: Ductility is the ability to deform under tensile stress.

Question: How to find the weight of the steel bar used in reinforcement?

Answer: Weight of Bar in Kg/m = D2/162.2

Where D = Diameter of bar in mm

Question: Why should curing not be done by Ponding and polythene sheets?

Answer: The primary purpose of the curing of the concrete is to reduce the heat loss of concrete that is freshly placed to the atmosphere and in order to reduce the temperature gradient across the cross-section (c/s) of the concrete. Ponding is not preferred for curing of the concrete as this method of thermal curing is greatly affected by cold winds.

In addition to that in Ponding large amounts of water are used and have to be disposed of from the construction sites. Polythene sheets are used on the basis that it creates an airtight environment around the concrete surface henceforth reducing the chance of evaporation over fresh concrete surfaces. But the usage of polythene can be a drawback as it can be easily blown away by winds & also the water lost by self-desiccation cannot be replenished.

Question: What is the difference between a one-way slab and a two-way slab?

Answer:

One way slab = Ratio of longer span/Shorter span ˃ 2

Two way slab = Ratio of longer span/Shorter span ≤ 2

Question: What is flat slab?

Answer: The slab which is supported on columns (Flat slab don’t have beams)

Question: What do you mean by one-storied, two-storied building?

Answer: The building has two floors is called two storied building.

Question: What is the height of each floor?

Answer: 3m

Question: Can you describe what a projection line is?

Answer: The projection line can be described as the way in which the earth is displayed on a flat piece of paper.

Question: List out the reinforcements that are used in the process of prestressing?

Answer: There are three primary types of reinforcements that are used in the prestressing process.

  • Spalling Reinforcements
  • Equilibrium Reinforcements
  • Bursting Reinforcements

Question: How would you describe the soundness of cement?

Answer: Cement soundness can be described as a property which ensures that the cement does not go through any appreciable expansion or experience any change in volume once it has been set. This process helps get rid of any possibilities of the mortar or concrete from getting disrupted.

Question: Explain Fatigue. Can you point out some of the structures that may be subjected to fatigue?

Answer: Fatigue can be described as the gradual damage to a structure that occurs when it is subjected to cyclic loading. Some of the structures that may be subjected to fatigue include:

  • Bridges that are heavily loaded
  • Hydraulic Presses
  • Aircrafts
  • Concrete Reservoirs
  • Pylons
  • Turbines
  • Overhead cranes
  • Transmission towers
  • Offshore platforms
  • Burners trains

Question: Describe the various types of slump test indications.

Answer: Slump tests are initiated to empirically measure the consistency of fresh concrete before it sets. They can also be used to check for an improperly mixed batch of concrete as well. There are three different types of slumps that occur in slump tests listed below:

  • Tue Slump
  • Shear Slump
  • Collapse Slump

Question: Explain the concept of built-up area and super built-up area.

Answer: Built-up area includes the carpet area as well as any space occupied by walls, pillars, and ducts.

The super built-up area covers the built-up area as well as any areas used by building amenities such as life passages, lobby, stairs, gym, clubhouse, etc.  

Question: What are some of the common roof types?

Answer: There are several types of roofs available. Some of the commonly used ones include:

  • Gable roof
  • Gambrel roof
  • Shed roof
  • Half-hipped roof
  • Dutch Hip roof
  • A-frame roof
  • Skillion roof
  • Folded plate roof
  • Gull wind roof
  • Bell cast roof
  • Sawtooth roof

Question: What is the length of riser and tread in the staircase?

Answer: Riser150mm to 200mm, Tread – 250mm to 300mm

Question: What is the slope of Staircase?

Answer: As IS: 456:2000, the slope or pitch of stairs should be between 25 degrees to 40 degrees.

Question: What do you mean by the moment of Inertia?

Answer: A quantity expressing a body’s tendency to resist angular acceleration, which is sum of the products of the mass of each particle in the body with the square of its distance from the axis of rotation.

Question: What is a cranks length in the slab?

Answer: The crank length in slab is 0.42D.

Where D is Depth of Slab- Top cover to Bottom Cover

Question: What is grouting?

Answer: Grouting is a fluid of concrete which is used to fill the voids.

Question: What do you mean by segregation?

Answer: Segregation of concrete is a separation of ingredients of concrete particles from concrete mix. This is caused due to the W/C ratio and when concrete is poured about more than 1.5m height.

Question: What is Seepage?

Answer: Slow percolation of water through soil is called Seepage.

Question: What is the Compressive Strength of brick?

Answer:

First class brick – 105 Kg/cm2

Second class brick – 70 Kg/cm2

Fire brick – 125 Kg/cm2

Question: How do you check the quality of cement on the site?

Answer: Date of manufacturing, color of cement, float test of cement

Question: What is the Initial and Final setting time of concrete?

Answer:

Initial setting time of cement – 30 mins

Final setting time of cement – 600 mins

Question: What is durability?

Answer: Ability to withstand under pressure is called durability.

Question: What are the tests on fresh concrete?

Answer: Slump test, compacting factor test, Vee – Bee test, Ball test

Question: What are tests on hardened concrete?

Answer: Cube test, Rebound hammer test, Ultrasonic pulse velocity test, Maturity test, Split tension test, Penetration resistance test

Question: What is bleeding in concrete?

Answer: Bleeding is one form of segregation, where water comes out to the surface of the concrete, being the lowest specific gravity among all the ingredients of concrete.

Question: What is the name of the machine to get a compression test?

Answer: Universal testing machine

Question: What is the function of stirrups in the column?

Answer: Stirrups are provided to handle the shear force and to hold the main bars in position.

Question: What is Modular Elasticity?

Answer: Young’s modulus (E) describes tensile elasticity or the tendency of an object to deform along an axis when opposing forces are applied along that axis; it is defined as the ratio of tensile stress to tensile strain.

Question: What is aggregate?

Answer: Aggregate is the components of a composite material used to resist compressive stress.

Question: What is the meaning of Soil Reinforcement?

Answer: Soil reinforcement is the act of improving soil strength to enable it to carry or support more load.

Ex. Mixing a soil amendment such as lime into weak clayey soil and recompacting to improve soil-bearing capacity.

Installing plastic or composite webbing layers alternating with compacted soil to produce a stronger sloped soil structure

Question: What is the world’s largest concrete dam?

Answer: The Grand Coulee Dam on the Columbia River is said to be the largest concrete dam. Currently, the world’s largest concrete dam is the Itaipu Dam, an accomplishment of two neighboring countries, Brazil and Paraguay in South Africa.

Though it is not finished yet, the Three Gorges Dam on the Yangtze River in China will take over as the largest upon its completion, which is slated for 2009.

Question: Which is stronger a solid steel rod or Hollow Steel Pipe?

Answer: On a per pound basis, the steel pipe is stronger in bending & is less likely to buckle in axial compression.

Question: How do you measure concrete?

Answer: Cubic feet, Cubic yards, Cubic meter.

Question: List out the potential risk factors for workers on the construction site?

Answer: Potential risk factor for the worker on the construction site is as below:

  • Falls from heights
  • Scaffold and Trench collapse
  • Electric shock and arc blast
  • Repetitive motion injuries
  • Not using personal protective equipment correctly

Question: What is Reinforced concrete?

Answer: Reinforced concrete has steel bars or meshes in them, which gives extra strength to the construction.

Question: Explain what is Hybrid foundation?

Answer: Hybrid foundation is usually used for high rise building, it contains both soils supported mat and piles. This type of foundation is helpful in decreasing the amount of the settlement.

Question: What are the common ways of demolition?

Answer:

Hydro-demolition

Pressure Bursting

Dismantling

Question: Explain what is floating slab foundation?

Answer: A floating foundation is a type of mat foundation that consists of the hollow mat formed by a grid of thick reinforced concrete walls between two thick reinforced concrete slabs.

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