Basic Knowledge of Civil Engineering | Thumb Rules:

Civil engineering is a diverse and complex field with its own unique principles, concepts, and terms. To succeed in a career in civil engineering, it’s essential to have a firm grasp of the fundamentals of this multifaceted science. This guide provides an overview of the fundamental concepts that everyone should know before delving deeper into civil engineering. Following are the Civil Engineering Basic Knowledge points to remember for civil engineers to make the construction work easier while maintaining the quality of work;

Civil Engineering Basics Knowledge:

• Basic Knowledge for Cement
• Basic Knowledge for Concrete
• Basic Knowledge for Beam and Slab, Column
• Basic Knowledge for Bricks

Basic Knowledge of Civil Engineering for Cement

• Cement, sand, and aggregate are used to identify concrete grades.
• The cement’s final setting time is 10 hours, while the starting setting time cannot be less than 30 minutes.
• A circular column must have a minimum of six longitudinal bars.
• Plain cement concrete (PCC)  When the tensile force is not acting on it, this form of concrete is used on members.
• A 50 kg cement bag takes up 0.3m2 of floor space and 0.18m of height.
• 50 kg of cement has a 1.3 CFT volume.
• Construction cannot be done with cement that is older than three months.

Basic Knowledge of Civil Engineering for Concrete

• Concrete shouldn’t be dropped from a height of more than one metre.
• For concrete mix, sand with a moisture level of at least 5% should be used.
• For every 30 cm3 of concrete used, a cube test is conducted.
• Ready-mix concrete, which is manufactured in a factory and delivered to the construction site, is used when there is insufficient space for mixing concrete and when a large volume of concrete is needed for a project.
• Hardened concrete develops cracks or honeycomb as a result of adding extra water to the concrete mix to speed up setting.
• DPC must have a minimum thickness of 2.5 cm.
• Concrete’s impermeability the type of concrete that is resistant to water or moisture.
• Concrete pumps can lift the concrete up to a maximum of 50 metres. The RCC cure time is 25 days.
• Concrete and steel have both thermal expansion coefficients with a value of 12 X10-6/Degree C.
• Typically, M20 grade concrete is used to build the slab.

Basic Knowledge of Construction for Beam, Slab and Column

• Hook length must be at least 9D.
• Theodolite’s minimum count is 20 seconds; while compass Least count is 30 mins.
• Each bar leaves the factory with a 12 m length.
• A head mason may complete 25–30 #3 projects per day. In the construction industry, man-hours are used to determine the rate analysis for labour.
• Simply supported beams have a minimum of two supports, while cantilever beams have one fixed support and the other end is free.
• Dead load is the structure’s own weight.
• Typically, the floor is 3 metres (10 feet) high.
• To remove the air bubble in the concrete mix, vibration is used when creating new concrete.
• The height of the sill level should be at least 44 inches.
• Tie refers to the transverse reinforcement that the column provides
  And they are known as stirrups when they arrive in beams.
• To handle the shear force and maintain the alignment of the longitudinal bars, stirrups are installed in the beams and ties in the columns.
• If the bar’s diameter is greater than 36 MM, lapping of bars is not permitted.
• The slab must be at least 0.125m thick.
• DPC must have a minimum thickness of 2.5 cm.
• Use of water with a PH of less than 6 is not advised for construction.
• Thermal expansion is the main justification for using steel as reinforcement.

Civil Engineering Basic Knowledge for Bricks

• The No. of bricks required for 1m³ of brick masonry is 550 Bricks.
• The weight of first-class clay brick should be 3.85 kg.
• The Crushing strength of brick 10.5 MN/m².
• The standard size of brick is 19cm X 9Cm X 4Cm.

Density of Construction Materials

• Bricks – 1600 – 1920 kg/m³
• Concrete block – 1920 kg/ m³
• Reinforce Concrete – 2310 – 2700 kg/ m³
• Plain cement Concrete– 2400 kg/m³
• Lime mortar– 1760kg/m³
• Aluminum – 2739 kg/m³
• Glass – 2580 kg/m³
• Zinc – 7135 kg/m³
• Clay soil – 1900 kg/m³
• Bamboo – 350 kg/m³

De-Shuttering Period of Different RCC Members

1. The period for column, wall, and vertical formworks – 16-24 hrs.
2. Period for Soffit formwork to slab – 3 days (props to be refixed after removal)
3. The period for Soffit to beam props – 7 days (props to be refixed after removal)
4. Beam spanning up to 4.5m – 7 days
5. Beam spanning over 4.5m – 14 days
6. Arche’s spanning up to 6m – 14 days
7. Arche’s spanning over 6m – 21 days

Min Nos. Of Concrete Cube Sample for Given Volume of Concrete

• 1 – 5 m³ = 1 Nos.
• 6 – 15 m³ = 2 Nos.
• 16 – 30 m³ = 3 Nos.
• 31 – 50 m³ = 4 Nos.
• Above 50 m³ = 4 + 1 Nos.

Basic Knowledge of Civil Engineering for Grades of Concrete

Clear Cover for main reinforcement

• CC For Beam: 25mm
• CC For Slab: 15mm
• CC For Flat slab: 20mm
• CC For Staircase: 15mm
• CC For Water tank Structure: 20 to 30 mm
• CC For Retaining Wall: 20 to 25mm to earth surface
• CC For Column: 40mm
• CC For Shear wall: 25mm
• CC For Raft foundation topside: 50mm
• CC For Raft foundation Bottom and Sides: 75mm

Different types of loads act on Building

1. Live Load
2. Dead Load
3. Wind Load
4. Self Load
5. Snow Load
6. Seismic Load or Earthquake load
7. Hurricane Load at some location

Slump Value for Different Concrete Works

Basic Knowledge of Civil Engineering for Interviews

1) Slope of Staircase

The slope of staircase varies from 25° to 40° as per the IS code 456-2000

2) Volume of Cement Bag

Weight of one   cement bag is 50 kg so the volume of 1 cement bag is 0.0347 m³ or 1.23 CFT

3) Expiry Date of Cement Bags

Expiry date is three month after the bag is packed.

4) Why is Foundation Provided?

Foundation should be provided in order to safely distribute the load of structure in the soil

5) Types of Foundations

• Shallow foundation
• Deep foundation

6) Calculation of weight of Steel bar

7) Minimum grade of concrete used for RCC

M20

8) Shuttering Removing Time

Side of wall column and Outer side of beam shuttering is removed after the 24 hours to 48 hrs of concrete. Beam soffits shuttering is removed after 7 (seven) days. Slab shuttering is removed after 3(three) days. Remove the props of the slab after 21 (twenty one) days of span greater than 6m and after 14 (fourteen) days of span less than 6m.

9) What are the Concrete Tests?

The Compressive strength test, Slump Test, Water absorption test, Water permeability test

10) What is the Unit Weight of Steel?

78.5 KN/m³ is the unit weight of steel.

11) Unit Weight of Concrete 

The unit weight of concrete of RCC (Reinforcement Cement Concrete) is 25 KN/m³ and PCC is 24 KN/m³

12) Compressive Strength of Bricks

Compressive Strength of First class Brick – 105 kg/cm²

Compressive Strength of Second class Brick – 70 kg/cm²

Compressive Strength of Fire Brick – 125 kg/cm²

13) The Setting Time of Cement

Initial setting time is 30 Mins And the final setting time of cement is 90 minutes.

14) Curing Methods of Concrete

Spraying, Wet covering of Surface, ponding, Curing chemicals, Steam curing, Sprinkling

15) Function of Stirrups in Beams?

Stirrups are used in beams to resist shear force

16) Need of Pile Foundation

Pile foundation is acquired when the soil bearing capacity is less than 24 KN/m³

17) Standard Height

Height of each floor is 3 M

18) Grouting

It is a process in which a mixture of cement and sand proportion of 1:3 (one in three) is shooted on the ground surface with the help of gun pressure of 2 to 3 kg/cm²

This basic questions are asked in interviews. Every engineers must kept this knowledge in your mind.

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