Junior Engineer interview Question |civil engineering

How we can decide the spacing of Main bar and Distribution bar ?

 The spacing of main bar and distribution bar depends on the design and load requirements of the structure. The spacing is determined by the structural engineer during the design phase.

  • It varies depending on the size and shape of the structure, as well as the load it will bear.
  • The spacing should be such that the reinforcement is evenly distributed throughout the structure.
  • For example, in a slab, the spacing of main bars may be 150mm to 200mm apart, while the distribution bars may be 200mm to 300mm apart.
  • The spacing should also comply with the relevant building codes and standards.

Maximum spacing of main bar is restricted to 3 times effective depth or 300 mm whichever is less. For distribution bars the maximum spacing is specified as 5 times the effective depth or 450 mm whichever is less.

Which IS code Rcc and Mix design concrete ?

IS code for RCC is IS 456:2000 and for mix design of concrete is IS 10262:2009.

  • IS 456:2000 provides guidelines for the design and construction of reinforced concrete structures.
  • IS 10262:2009 provides guidelines for the proportioning of concrete mixes based on the desired strength and workability.
  • Both codes are important for ensuring the quality and durability of concrete structures.

How is mixing time in concrete ?

Mixing time in concrete is the duration required to achieve a homogeneous mixture of all the ingredients.

  • Mixing time depends on the type of mixer used.
  • It also depends on the quantity of ingredients and their properties.
  • The ideal mixing time is usually specified by the manufacturer or as per the design requirements.
  • Over-mixing can lead to a decrease in the strength of concrete.
  • Under-mixing can result in the formation of voids and weak spots in the concrete.

Minimum mixing time of 1-1/2 minute, which is standard procedure at the present time.

Standard sand in India is obtained from ?

  • Standard sand in India is obtained from the river beds of Godavari, Krishna, Cauvery, and Pennar.
  • It is used for testing the quality of cement and concrete.
  • The sand is sieved through a 1.18mm sieve before being used for testing purposes.

 What is water cement ratio ?

Water cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix.

  • It is an important factor in determining the strength and durability of concrete.
  • A lower water cement ratio results in stronger and more durable concrete.
  • The ideal water cement ratio varies depending on the type of concrete and its intended use.
  • For example, a water cement ratio of 0.45 is recommended for concrete used in bridges and other structures exposed to harsh weather conditions.

Does lapping length depends in concrete grade ?

Yes, lapping length depends on concrete grade.

  • Lapping length is the length of overlap required for reinforcing bars in concrete.
  • It ensures the transfer of stress from one bar to another.
  • Higher concrete grades require longer lapping lengths for proper bond and strength.
  • For example, in grade M20 concrete, the lapping length for tension bars is typically 50 times the diameter of the bar.

What is FAR ? 

 FAR stands for Floor Area Ratio, which is the ratio of a building’s total floor area to the size of the plot of land it is built on.

Explain Lapping zone in column ?

Lapping zone in column is the overlapping region where two reinforcement bars are joined together.

  • Lapping zone is created to ensure continuity of reinforcement in the column.
  • It helps in transferring the load from one bar to another without any interruption.
  • The length of the lapping zone depends on the design requirements and the diameter of the reinforcement bars.
  • Proper lapping of reinforcement bars is essential to maintain the strength and integrity of the column.
  • Lapping is usually done by overlapping the bars for a certain length and then tying them together with wire or using mechanical splices.
  • Example: In a column, if the reinforcement bars need to be extended beyond their available length, lapping is done to join the bars together.