RRB JE Civil Engineering Questions with Detailed Solutions

Correct Answer: A. Brush

Explanation:

The brush injection method is considered the simplest epoxy injection method used in repair and maintenance works. In this method, epoxy resin is applied directly to the crack or damaged surface using a brush. It is suitable for sealing fine surface cracks and pores where deep penetration or pressure injection is not required. Since it does not require pumps, injection ports, or specialized equipment, it is the simplest and most economical method.

Explanation of Other Options:

B. Low Pressure

Low-pressure injection uses injection ports and pumping equipment to force epoxy into cracks under controlled pressure. It is more effective for deeper cracks but requires additional setup and equipment.

C. Hand Gun

Hand gun injection uses a cartridge-based gun to inject epoxy into cracks. Although relatively simple, it still requires specialized tools and is more involved than the brush method.

D. High Pressure

High-pressure injection is used for structural crack repairs and requires specialized pumps and equipment. It is the most complex among the given methods.

Conclusion:

Since the brush method requires only manual application of epoxy without any injection equipment, it is regarded as the most simple epoxy injection method.

Answer: A. Brush.

Answer: C. Bay window

Explanation:

A bay window is a window that projects outward from the external wall of a building, forming a small alcove or recess inside the room. It generally consists of one central window and two side windows set at angles, thereby increasing the floor area, improving natural lighting, and providing a wider view of the outside surroundings.

Bay windows are commonly used in residential buildings for architectural beauty and enhanced interior space. The projection beyond the wall line creates an attractive appearance and allows more sunlight and ventilation to enter the room.

The other options are different types of windows:

• Casement window is hinged to the frame and opens like a door.
• Sliding window opens by sliding the shutters horizontally or vertically.
• Fixed window cannot be opened and is provided mainly for light and visibility.

Therefore, a window that projects outward from the wall surface to form a small alcove is called a bay window.

Correct Option: C. Bay window

Answer: B. Mosaic flooring

Explanation:

Mosaic flooring is a decorative flooring in which small pieces of broken tiles, marble, glass, or other suitable materials are arranged in desired patterns over a cementing layer. After laying, the surface is ground and polished to obtain a smooth, durable, and attractive finish.

Terrazzo flooring differs from mosaic flooring in that marble chips are mixed uniformly with cement and laid as a continuous topping, whereas in mosaic flooring the pieces are individually arranged to create specific designs and patterns.

Therefore, a flooring made of small pieces of broken tiles or marble arranged in desired patterns on a cementing layer is called mosaic flooring.

Correct Option: B. Mosaic flooring

Correct Answer: B) Flush pointing

In flush pointing, the mortar in the joints is pressed and finished flush with the face of the masonry wall, resulting in a flat and even surface that aligns with the wall face.

·         A) Recessed pointing: The mortar is pressed back from the wall face, creating a recessed profile.

·         C) Beaded pointing: The mortar projects outward in the form of a bead.

·         D) V pointing: The joint is finished with a V-shaped groove.

Since the profile has a flat surface that aligns with the face of the wall, the correct answer is:

B) Flush pointing

Answer: B. Polymeric

Explanation:

Epoxy adhesives are synthetic resin adhesives formed by the reaction of epoxy resins with hardeners. They belong to the class of polymeric adhesives because their bonding action is based on polymer compounds that develop strong adhesive and cohesive properties after curing.

Epoxy adhesives are widely used in construction and engineering applications due to their excellent bonding strength, chemical resistance, durability, low shrinkage, and ability to adhere to a variety of materials such as concrete, steel, wood, glass, and plastics.

Water-borne and latex adhesives are generally based on aqueous dispersions, whereas epoxy adhesives are thermosetting polymeric adhesives. Polyester adhesives form a separate category of synthetic resin adhesives and are different from epoxy adhesives.

Therefore, epoxy adhesives are classified under polymeric adhesives.

Correct Answer: A. Grader

Explanation:

A grader, also known as a motor grader, is a construction machine specifically designed for grading, leveling, and finishing large areas of land. It consists of a long adjustable blade located between the front and rear wheels, which is used to cut, spread, and level soil to the desired grade.

Graders are widely used in road construction, airport runways, earthwork projects, and site development works where a smooth and accurate surface is required. They are particularly suitable for final grading operations because they provide precise control over the slope and elevation of the ground.

Explanation of Other Options:

B. Bulldozer

A bulldozer is primarily used for pushing soil, clearing land, removing obstacles, and rough grading. Although it can perform some leveling work, it does not provide the precision required for final grading over large areas.

C. Excavator

An excavator is mainly used for digging, trenching, excavation, demolition, and material handling. It is not intended for grading and leveling large surfaces.

D. Scraper

A scraper is used for cutting, loading, hauling, and spreading earth over relatively long distances. While it can assist in rough leveling, it is not as effective or accurate as a grader for final grading operations.

Conclusion:

Since a grader is specifically designed to produce smooth, level, and accurately graded surfaces over large areas, the correct answer is:

Answer: A. Grader

Correct Answer: D. 1.6%

Explanation:

Water absorption of an aggregate is defined as the percentage increase in weight of the aggregate due to the absorption of water with respect to its oven-dried weight.

The water absorption is calculated using the following expression:

​$$\frac{W_{SSD}-W_{OD}}{W_{OD}}\times100$$

Where:

• SSD Weight (Saturated Surface Dry Weight) = 5.08 kg
• Oven-Dry Weight = 5.00 kg

Substituting the given values:

$$\text{Water Absorption (\%)}=\frac{5.08-5.00}{5.00}\times100$$

                                      $$=\frac{0.08}{5.00}\times100$$

                                      $$=1.6\%$$

​​​​Therefore, the water absorption percentage of the aggregate is 1.6%.​

​

Correct Answer: C. shrink; expand

Explanation:

Grout is a fluid material used to fill cracks, voids, joints, and gaps in masonry, concrete, and rock formations. A good grout should possess the property of slight expansion after placement so that it completely fills the available space and ensures proper bonding.

If grout shrinks during setting, gaps may develop between the grout and the surrounding surface, reducing its effectiveness. Therefore, grout materials are formulated so that they do not shrink and instead slightly expand to achieve complete filling of voids.

Hence, the materials of a grout should not shrink, but should expand to fill gaps.

Explanation of Other Options:

A. condense; evaporate

Condensation and evaporation are not desirable properties of grout and are unrelated to its filling action.

B. harden; crumble

Grout must harden after placement, but it should never crumble.

D. expand; shrink

This is opposite to the required behavior of grout.

Conclusion:

To ensure complete filling of voids and proper bonding, grout materials should not shrink and should slightly expand after placement.

Answer: C. shrink; expand.

Correct Answer: D. Chopped Straw

Explanation:

In the construction of mud floors, chopped straw is mixed with the mud to prevent the formation of cracks. Mud undergoes shrinkage as it dries, which can lead to the development of cracks on the floor surface. The chopped straw acts as a reinforcing material by distributing the shrinkage stresses throughout the mud mass.

The straw fibres improve the cohesion of the mix, increase its tensile resistance, and reduce the likelihood of crack formation. This traditional practice has been widely used in rural construction because it is economical, readily available, and effective in enhancing the durability of mud floors.

Explanation of Other Options:

A. Fine Muram

Fine muram is sometimes added to improve the strength and compactness of the floor. However, its primary function is not to prevent shrinkage cracks.

B. Sand

Sand is added to improve the texture and reduce excessive shrinkage of clay-rich soil, but it is not as effective as fibrous materials in controlling crack formation.

C. Natural Resin

Natural resin may be used as a stabilizing or waterproofing additive in some traditional constructions, but it is not the material commonly used to prevent cracking in mud floors.

Conclusion:

Since chopped straw acts as a natural fibre reinforcement that controls shrinkage and prevents the formation of cracks during drying, it is the material used in mud floor construction for crack prevention.

Answer: D. Chopped Straw.

Answer: D. Dormant cracks

Explanation:

Epoxy injection is a commonly used repair technique for restoring the structural integrity of cracked concrete members. In this method, low-viscosity epoxy resin is injected under pressure into the cracks, filling the voids and bonding the cracked surfaces together.

This method is most effective for dormant cracks, which are cracks that have ceased to move and are no longer widening or changing in width. Since epoxy forms a rigid and high-strength bond, it can successfully restore the original strength and stiffness of the concrete element.

Epoxy injection is not suitable for active, moving, or expanding cracks because continued movement after repair may cause the rigid epoxy bond to crack again. Such cracks generally require flexible sealants or other specialized repair methods.

Therefore, epoxy injection is effectively used for the repair of dormant cracks.

Correct Option: D. Dormant cracks

Correct Answer: C. Scaffolding

Explanation:

For trenches deeper than 4 feet, safe access and egress must be provided to allow workers to enter and exit the trench quickly and safely. Commonly accepted methods of access and egress include ladders, ramps, and steps. These means are specifically designed to facilitate safe movement of workers and are recognized in excavation safety regulations.

Scaffolding is not considered a proper access and egress method for a trench. Scaffolding is a temporary structure used to provide working platforms at elevated locations and is not intended for entering or exiting excavations. Using scaffolding for trench access may create unsafe conditions and does not satisfy standard excavation safety requirements.

Explanation of Other Options:

A. Steps

Steps provide a safe and convenient means for workers to enter and exit trenches, especially when properly constructed and maintained.

B. Ramps

Ramps are widely used for access and egress in trenches and excavations. They allow safe movement of workers, equipment, and materials when designed according to safety standards.

D. Ladders

Ladders are the most commonly used means of access and egress for trenches. Safety regulations generally require ladders to be placed so that workers do not have to travel excessive distances within the trench to reach them.

Conclusion:

Since scaffolding is intended to provide elevated working platforms rather than access to excavations, it is not considered a proper access and egress method for a trench deeper than 4 feet.

Answer: B. Building Bye Laws

Explanation:

Building Bye Laws are the rules and regulations framed by a municipal corporation, development authority, or local governing body to regulate and control building activities within its jurisdiction. These regulations ensure that buildings are planned, designed, and constructed in a safe, healthy, and orderly manner.

Building Bye Laws generally specify:

• Minimum plot sizes and setbacks
• Floor Area Ratio (FAR) or Floor Space Index (FSI)
• Building height restrictions
• Requirements for ventilation and lighting
• Fire safety provisions
• Sanitation and drainage requirements
• Structural safety requirements

The primary objective of Building Bye Laws is to promote public health, safety, convenience, and planned urban development.

The other options are incorrect because:

• Construction Ordinances is not the standard term used for municipal building regulations.
• Codes of Practice provide technical guidelines but do not constitute local statutory regulations.
• Gazetted Rules are rules published in a government gazette and are not specifically the regulations governing building development within a municipality.

Therefore, the rules and regulations framed by a municipal corporation to control development under its jurisdiction are called Building Bye Laws.

Correct Answer: D) Centrally for convenience

In public buildings such as hospitals, the administrative department should be located centrally so that it is easily accessible from various sections of the building. A central location facilitates:

·         Efficient supervision and management

·         Better coordination between departments

·         Convenient access for staff, patients, and visitors

·         Improved communication and operational efficiency

·         A) At the back of the building for security: Reduces accessibility and operational efficiency.

·         B) In an area with the best outside view: Aesthetic considerations are secondary to functionality.

·         C) In the farthest corner for privacy: Makes access difficult for users and staff.

For effective administration and ease of access, the administrative department should be located:

D) Centrally for convenience

Answer: High ductility

Explanation:

Carbon fibre is an advanced engineering material widely used in aerospace, construction, automobile, and sports industries due to its excellent mechanical properties. It possesses very high strength-to-weight ratio and high stiffness, making it suitable for applications where lightweight and high strength are required.

The important properties of carbon fibre include:

• High stiffness, which enables it to resist deformation under load.
• High corrosion resistance, making it durable in aggressive environmental conditions.
• Low thermal conductivity compared to most metals, which reduces heat transfer.
• High tensile strength and low density, resulting in lightweight structural members.

However, carbon fibre is a brittle material and does not undergo significant plastic deformation before failure. Ductility is the property of a material to deform considerably under tensile stress before rupture. Since carbon fibre fractures suddenly without appreciable elongation, it cannot be considered a ductile material.

Therefore, high ductility is not a property of carbon fibre.

Answer: D. Atmospheric action on foundation

Explanation:

Plinth protection is a protective layer, usually made of cement concrete, brick paving, stone paving, or similar impervious material, provided around the exterior perimeter of a building at ground level. Its primary purpose is to prevent the ingress of surface water and rainwater into the soil adjacent to the foundation.

Without plinth protection, water can accumulate near the building walls and seep into the ground, causing erosion, settlement, dampness, and deterioration of the foundation. By directing water away from the building, plinth protection safeguards the foundation against the harmful effects of weather and moisture.

Thus, plinth protection helps protect the foundation from atmospheric actions such as rainfall, moisture penetration, and weathering effects.

Therefore, plinth protection along external walls is essential to prevent atmospheric action on the foundation.