50+ L&T Construction Interview Questions and Answers for Freshers

The cost of painting the wall behind me cannot be determined without additional information.

• The cost of painting a wall depends on various factors such as the size of the wall, the type of paint used, and the labor charges.

• Additional information needed includes the dimensions of the wall, the type of paint desired, and the cost of labor per square foot or hour.

• Once these details are provided, an estimate can be calculated by multiplying the area of the wall by the cost per sq...read more

M25 concrete is a mix of concrete with a compressive strength of 25 MPa.

• M25 concrete is commonly used in construction for foundations, columns, and beams.

• It is made by mixing cement, sand, and coarse aggregates in a ratio of 1:1:2.

• The water-cement ratio should be around 0.45 for M25 concrete.

• The compressive strength of M25 concrete is achieved after 28 days of curing.

• M25 concrete is suitable for moderate exposure conditions.

After receiving the plan of a construction, the following steps should be followed.

• Review the plan thoroughly to understand the scope and requirements of the project.

• Identify any potential issues or conflicts in the plan and communicate them to the relevant stakeholders.

• Create a detailed project schedule and timeline based on the plan.

• Allocate resources and manpower according to the requirements of the plan.

• Obtain necessary permits and approvals for the construction.

• Procure m...read more

Concrete tests are used to determine the strength and quality of concrete.

• Compression test measures the strength of concrete under compression

• Slump test measures the consistency and workability of fresh concrete

• Air content test measures the amount of air trapped in concrete

• Water permeability test measures the ability of concrete to resist water penetration

• Rebound hammer test measures the surface hardness of concrete

Water absorption test is a measure of the amount of water absorbed by a material under specified conditions.

• The test is used to determine the porosity and permeability of a material.

• It involves immersing the material in water for a specified period of time and then measuring the weight gain.

• The percentage of weight gain is calculated and used to determine the water absorption rate of the material.

• The test is commonly used in the construction industry to evaluate the durabilit...read more

Chain surveying is time-consuming and requires skilled personnel.

• Requires a lot of time and effort to set up and measure accurately

• Not suitable for large areas or uneven terrain

• Errors can accumulate quickly and lead to inaccurate results

• Requires skilled personnel to operate and interpret data

• Difficult to use in areas with obstacles or obstructions

• May not be suitable for certain types of surveys, such as topographical surveys

Various types of protection used in generators, transformers, and grounding.

• Generator protection includes overcurrent, differential, and reverse power protection.

• Transformer protection includes overcurrent, differential, and Buchholz protection.

• Grounding protection includes earth fault protection and lightning protection.

• Other types of protection include overvoltage, underfrequency, and thermal protection.

• Each type of protection is designed to prevent damage to the equipment ...read more

Bending moment diagram for cantilever beam with UDL

• Calculate the reaction force at the fixed end

• Determine the equation of the bending moment curve

• Plot the bending moment diagram

• The maximum bending moment occurs at the fixed end

• The area under the bending moment curve represents the shear force

I have experience in rating generators and transformers from my internship at NALCO Captive Power Plant.

• During my internship, I learned how to rate generators and transformers based on their capacity and efficiency.

• I gained hands-on experience in using instruments to measure the performance of generators and transformers.

• I also learned about the importance of regular maintenance and testing to ensure optimal performance.

• For example, I assisted in conducting routine tests on t...read more

Bending moment diagram for propped cantilever with UDL

• Calculate the reactions at the support and the prop

• Draw the shear force diagram

• Calculate the maximum bending moment at the fixed end

• Draw the bending moment diagram

• Include the effect of the UDL on the bending moment diagram

Types of faults in transmission lines

• Short circuit fault

• Open circuit fault

• Ground fault

• Transient fault

• Intermittent fault

The PCB design process involves several steps from schematic design to manufacturing.

• 1. Schematic design: Create a schematic diagram of the circuit layout.

• 2. Component placement: Arrange components on the PCB layout.

• 3. Routing: Connect components using traces on the PCB.

• 4. Design verification: Check for errors and ensure functionality.

• 5. Gerber file generation: Create files for manufacturing.

• 6. Prototyping: Build a prototype for testing.

• 7. Manufacturing: Produce the final PCB...read more

Assumptions made in limit state method

• Assumption of failure criteria

• Assumption of load distribution

• Assumption of material properties

• Assumption of boundary conditions

• Assumption of safety factors

• Assumption of design life

• Assumption of environmental conditions

Mho relay is a type of distance relay used for fault detection in power systems. Generators operate in parallel to increase power output.

• Mho relay is a directional relay that operates based on the impedance seen by the relay during a fault.

• Generators in parallel must have the same voltage, frequency, and phase sequence to avoid damaging the system.

• Parallel operation of generators requires synchronization and load sharing control.

• Parallel operation can increase power output an...read more

Concrete compensation percentage varies based on factors like experience, location, and company size.

• Concrete compensation percentage can range from 5% to 20% of the total project cost.

• Factors influencing concrete compensation percentage include experience level of the engineer, location of the project, and size of the company.

• For example, a junior civil site engineer may receive a lower percentage compared to a senior engineer working in a metropolitan area for a large const...read more

The grade of concrete refers to its strength and is classified based on its compressive strength.

• Concrete grades range from M5 to M100, with M representing mix and the number representing the compressive strength in megapascals (MPa).

• The most commonly used grades of concrete are M20, M25, and M30.

• Higher grade concrete is used for structures that require greater strength, such as bridges and high-rise buildings.

• The grade of concrete is determined by testing a sample of the con...read more

The question asks about years of experience in a construction company, plaster work size, and M20 grade concrete ratio.

• Years of experience in a construction company

• Plaster work size

• M20 grade concrete ratio

Design of steel & concrete structures involves the use of mathematical calculations and engineering principles to create safe and efficient structures.

• Structural analysis and design

• Material selection and testing

• Load calculations and distribution

• Construction techniques and methods

• Code compliance and safety regulations

Concrete ratio is the proportion of cement, sand, and aggregate in a concrete mix.

• Concrete ratio is typically expressed as a ratio of cement:sand:aggregate, such as 1:2:4.

• The ratio may vary depending on the strength and durability requirements of the concrete mix.

• Common concrete ratios include 1:1.5:3, 1:2:4, and 1:3:6.

• The grade of concrete (e.g. M20, M25) also determines the concrete ratio.

There are two types of distribution systems: radial and network.

• Radial distribution system is a simple and common system where power flows in one direction from the source to the load.

• Network distribution system is a complex system where power flows in multiple directions through interconnected feeders and transformers.

• Radial system is suitable for areas with low power demand and less number of consumers.

• Network system is suitable for areas with high power demand and more num...read more

Power system protection is a set of measures taken to ensure the safety and reliability of electrical power systems.

• Power system protection involves detecting and isolating faults in the power system to prevent damage to equipment and ensure continuity of power supply.

• Protection devices such as relays, fuses, and circuit breakers are used to detect and isolate faults.

• Relays are used to detect abnormal conditions in the power system and send signals to circuit breakers to isol...read more

Demux and mux are short for demultiplexing and multiplexing, respectively. They are used in signal processing to separate or combine multiple signals.

• Demux (demultiplexing) is the process of separating a single input signal into multiple output signals.

• Mux (multiplexing) is the process of combining multiple input signals into a single output signal.

• Demux is commonly used in telecommunications to separate different data streams from a single transmission line.

• Mux is used in vi...read more

I chose civil engineering because I enjoy designing and building structures that improve society.

• Passion for designing and building structures

• Desire to contribute to society through infrastructure projects

• Interest in problem-solving and innovation in construction

• Opportunity to work on diverse projects such as bridges, roads, and buildings

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Polymorphism is the ability of a function or method to behave differently based on the input data type.

• Prime numbers are numbers that are only divisible by 1 and themselves, such as 2, 3, 5, 7, 11, etc.

• Polymorphism allows a function or method to work with different data types, such as overloading in programming languages like Java or C++.

The aim of a civil engineer is to design, construct, and maintain infrastructure that improves the quality of life for society.

• Designing and planning infrastructure projects such as roads, bridges, and buildings

• Ensuring the safety and functionality of structures

• Managing construction projects and overseeing the work of contractors

• Using innovative techniques and materials to improve efficiency and sustainability

• Contributing to the development of sustainable and resilient cities...read more

Concrete grades are classified based on their strength and durability.

• Concrete grades range from M5 to M100.

• M stands for mix and the number after it represents the compressive strength of concrete in megapascals (MPa).

• Higher grade concrete is used for heavy-duty structures like bridges and dams, while lower grade concrete is used for lighter structures like sidewalks and driveways.

To draw SFD and BMD for simply supported beam under UDL of 10KM/m, follow these steps:

• Calculate the reactions at the supports

• Draw the SFD by taking the upward forces as positive and starting from one end

• Draw the BMD by taking the positive moment as clockwise and starting from one end

• Mark the maximum values of SFD and BMD

• Check the equilibrium and compatibility of the beam

The size of a parapet wall can vary depending on the specific design requirements and building codes.

• The typical height of a parapet wall is around 3 feet, but it can be higher for safety reasons or aesthetic purposes.

• The thickness of a parapet wall is usually around 8 inches to provide structural support.

• The length of a parapet wall will depend on the length of the building facade it is protecting.

• Parapet walls can be made of various materials such as brick, concrete, or met...read more

Bucholz Relay is a protective device used in oil-immersed transformers to detect and prevent faults.

• It is installed between the transformer tank and conservator tank.

• It detects faults such as internal short circuits and incipient faults.

• It operates on the principle of gas evolution due to the decomposition of oil.

• It sends a signal to the transformer protection system to isolate the transformer from the power system.

• It consists of two elements - a float switch and a mercury sw...read more

Concrete setting is the process in which concrete hardens and gains strength over time.

• Concrete setting is the transformation of concrete from a plastic state to a hardened state.

• It involves a chemical reaction called hydration, where water reacts with the cement in the concrete mixture.

• The setting time of concrete can vary depending on factors like temperature, humidity, and mix design.

• Proper curing is essential to ensure the concrete reaches its full strength potential.

• Exam...read more

Column cover size refers to the dimensions of the material used to cover or encase a structural column.

• Column cover size is typically specified in terms of width, depth, and height.

• It is important to consider the aesthetic and functional requirements when determining the column cover size.

• Examples of column cover materials include metal, wood, stone, or composite materials.

• Column cover size can vary depending on the design and structural requirements of the building.

Beam cover is the distance between the outer face of the concrete beam and the outer face of the column or slab.

• Beam cover is important for protecting the reinforcement bars from corrosion and fire damage.

• It also helps in providing adequate strength and durability to the structure.

• The beam cover requirement may vary based on the type of structure and environmental conditions.

• For example, in coastal areas where there is a higher risk of corrosion, a larger beam cover may be re...read more

My favorite subject is mathematics because I enjoy solving complex problems and using logic to find solutions.

• I love working with numbers and equations

• I find joy in solving challenging math problems

• I appreciate the logical reasoning involved in mathematics

Grab is a Southeast Asian ride-hailing, food delivery, and financial services company. The Pipeline is a program to develop tech talent.

• Grab is headquartered in Singapore and operates in 8 countries.

• It offers various services like ride-hailing, food delivery, and financial services.

• The Pipeline is a program to develop tech talent in Southeast Asia.

• It provides training and mentorship to aspiring tech professionals.

• The program also offers job opportunities at Grab and partner c...read more

Compressive strength of bat bricks refers to the maximum load-bearing capacity of the bricks under compression.

• Compressive strength is an important property of bricks used in construction.

• It is measured in units of force per unit area, such as N/mm² or psi.

• The compressive strength of bat bricks can vary depending on factors such as the type of clay used, the firing temperature, and the moisture content.

• For example, a typical compressive strength for bat bricks might be around...read more

Torque variation in squirrel cage motors is achieved by changing the rotor resistance.

• Torque in squirrel cage motors can be varied by changing the rotor resistance.

• Increasing the rotor resistance will increase the torque produced by the motor.

• Decreasing the rotor resistance will decrease the torque produced by the motor.

• This method is commonly used in applications where variable torque is required, such as in fans or pumps.

Safety is the practice of preventing accidents, injuries, and harm to people, property, and the environment.

• Safety involves identifying and assessing potential hazards and implementing measures to control or eliminate them.

• It includes promoting awareness and education about safety procedures and protocols.

• Safety also involves enforcing regulations and standards to ensure compliance.

• Examples of safety measures include wearing personal protective equipment, implementing fire sa...read more

A hazard is a potential source of harm or danger that can cause injury, illness, or damage to property.

• A hazard can be a physical, chemical, biological, or ergonomic factor that has the potential to cause harm.

• Examples of hazards include slippery floors, toxic chemicals, infectious diseases, and repetitive motion injuries.

• Hazards can be present in various environments such as workplaces, homes, and public spaces.

• Identifying and assessing hazards is crucial in order to impleme...read more

Pavement is a hard surface constructed on top of a base layer to support vehicular or foot traffic.

• Pavements are typically made of materials like asphalt, concrete, or bricks.

• They are constructed by first preparing the subgrade, then adding a base layer for support, followed by the pavement material.

• Pavements can be designed for different traffic loads and environmental conditions.

• Proper drainage is important in pavement construction to prevent water damage.

• Regular maintenanc...read more

Resistance is the opposition to the flow of electric current, while machines are devices that convert energy from one form to another.

• Resistance is measured in ohms and is caused by the material and dimensions of a conductor.

• Machines include motors, generators, transformers, and other devices that use electrical energy to perform work.

• Resistance can be calculated using Ohm's Law: R = V/I, where R is resistance, V is voltage, and I is current.

Challenges in electrical industry include rapid technological advancements, safety concerns, and skilled labor shortage.

• Rapid technological advancements leading to constant need for upskilling and training

• Safety concerns related to electrical hazards and compliance with regulations

• Skilled labor shortage impacting project timelines and quality of work

• Integration of renewable energy sources and smart grid technologies

Fire is a chemical reaction that releases heat, light, and various gases.

• Fire is a rapid oxidation process that occurs when fuel, heat, and oxygen are present.

• It can be classified into different types based on the fuel source, such as Class A, B, C, D, and K fires.

• Fire can cause property damage, injuries, and fatalities if not controlled properly.

• Prevention measures include proper storage of flammable materials, regular maintenance of electrical systems, and having fire extin...read more

Synchronous motor is a type of AC motor where the rotation of the shaft is synchronized with the frequency of the supply current.

• Synchronous motor has a rotor with electromagnets and stator with field windings.

• The rotor rotates at the same speed as the rotating magnetic field produced by the stator.

• It requires DC excitation to create a magnetic field in the rotor.

• Used in applications where constant speed is required, such as in power plants and industrial processes.

Speed and torque variation methods are used in electrical systems to control the performance of motors.

• Speed variation methods include changing the frequency of the power supply or using variable speed drives.

• Torque variation methods involve adjusting the voltage or current supplied to the motor.

• Examples of speed variation methods include VFDs (Variable Frequency Drives) and soft starters.

• Examples of torque variation methods include adjusting the field weakening in DC motors ...read more

The width of pavement varies depending on the type of road and number of lanes.

• Width of pavement can range from 10 feet for a single lane road to over 100 feet for a multi-lane highway

• Standard width for a two-lane road is typically around 24 feet

• Interstate highways can have pavement widths of up to 48 feet per lane

Machines operate based on various principles such as electromagnetic, mechanical, thermal, and chemical principles.

• Machines convert one form of energy into another to perform work

• Electromagnetic machines use the principles of electricity and magnetism, like motors and generators

• Mechanical machines use moving parts to transfer and transform energy, like engines and gears

• Thermal machines use heat to generate power, like steam engines

• Chemical machines involve chemical reactions ...read more

A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction.

• Transformers work on the principle of electromagnetic induction

• They have primary and secondary coils wound around a core

• Step-up transformers increase voltage while step-down transformers decrease voltage

• Efficiency of a transformer is determined by its core material and design

M15 ratio is the mix ratio of cement, sand, and aggregate in construction.

• M15 ratio is commonly used in construction for preparing concrete.

• It refers to the mix ratio of 1:2:4, which means 1 part cement, 2 parts sand, and 4 parts aggregate.

• This ratio is suitable for general construction purposes where high strength is not required.

Initial setting time of rhc is the time taken for the cement paste to lose its plasticity and become rigid.

• Initial setting time is typically around 30 minutes for ordinary Portland cement.

• It is influenced by factors such as temperature, water-cement ratio, and type of cement used.

• Testing for initial setting time is done using the Vicat apparatus.

Ohm's law is limited to linear, passive circuits with constant temperature and material properties.

• Ohm's law only applies to linear circuits where voltage is directly proportional to current.

• It assumes constant temperature and material properties, which may not always be the case.

• Non-linear components like diodes and transistors do not follow Ohm's law.

• Ohm's law does not account for reactive components like capacitors and inductors.

• It is not applicable in situations where the...read more

Aquifer is a layer of permeable rock that contains and transmits groundwater. Sand boiling is a phenomenon that occurs during earthquakes.

• Aquifer is a natural underground reservoir that holds water and allows it to flow through it.

• It is made up of permeable rocks like sandstone, limestone, and gravel.

• Sand boiling is a phenomenon that occurs during earthquakes when the ground shakes violently and water-saturated sand boils up to the surface.

• It is also known as liquefaction and...read more

Alternator produces AC current while generator produces DC current.

• Alternator has stationary armature and rotating magnetic field while generator has rotating armature and stationary magnetic field.

• Alternator is more efficient and reliable than generator.

• Alternator is commonly used in modern vehicles while generator is used in older vehicles.

• Alternator produces higher output voltage than generator.

• Alternator requires less maintenance than generator.

V/F speed control is a method of controlling the speed of an AC motor by varying the frequency and voltage supplied to the motor.

• V/F speed control is commonly used in applications where precise speed control is not required, such as fans, pumps, and conveyor belts.

• By adjusting the frequency and voltage supplied to the motor, the speed of the motor can be controlled without the need for complex control systems.

• This method is cost-effective and simple to implement compared to o...read more

The gear box functions to transfer power from the engine to the wheels, allowing the vehicle to change speed and direction.

• Transfers power from the engine to the wheels

• Allows the vehicle to change speed and direction

• Consists of gears that mesh together to provide different gear ratios

Reinforcement of concrete involves adding materials like steel bars to increase its strength and durability.

• Reinforcement helps to prevent cracking and increase load-bearing capacity.

• Common reinforcement materials include steel bars, mesh, and fibers.

• Reinforcement is typically placed in areas of concrete that are prone to tension or bending forces.

• Proper placement and spacing of reinforcement is crucial for effective reinforcement.

• Examples of reinforced concrete structures in...read more