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Past Questions
Which of the following is the desirable property of soil as highway material?
A)
Stability, Good drainage, Ease of compaction
B)
Compressibility
C)
Highly permeable
D)
Soil that has considerable changes in volume and stability under adverse conditions of weather and ground water.
In highway engineering, the subgrade and base layers must support heavy traffic loads without significant deformation. Therefore, the desirable properties of soil used as highway material are:
1. Stability: The soil must be able to withstand traffic loads without shearing or failing.
2. Good Drainage: Water is the primary enemy of pavements. Soil with good drainage prevents the buildup of pore water pressure and protects the road from frost heave or saturation-induced softening.
3. Ease of Compaction: To achieve maximum dry density and strength, the soil must be easily compactable using standard machinery.
Why other options are incorrect:
- Option b (Compressibility): High compressibility leads to settlement and rutting of the pavement, which is undesirable.
- Option c (Highly permeable): While drainage is needed, 'highly permeable' soils (like coarse sands) may lack the necessary cohesive strength or stability to support the pavement structure without stabilization.
- Option d (Changes in volume): Soil that changes volume (swelling and shrinking) based on moisture content (e.g., Black Cotton Soil) causes cracks and waves in the road surface, making it highly undesirable.
The minimum clear cover recommended by IS code for Column ties is:
A)
25mm or bar diameter
B)
40mm or bar diameter
C)
50 mm
D)
40mm or 2 times diameter of ties
According to IS 456:2000 (the Indian Standard code of practice for Plain and Reinforced Concrete), the nominal cover to reinforcement is specified to ensure durability and fire resistance. For columns, the nominal cover is generally specified as 40 mm. However, the code stipulates that the cover should be the greater of 40 mm or the diameter of the main reinforcing bar. While 'clear cover' and 'nominal cover' are technically different (nominal cover includes the half-diameter of the stirrup/tie), in the context of standard competitive exams for Junior Engineers based on IS 456, the requirement for columns is recognized as 40 mm or the diameter of the bar. Option (a) is typically associated with slabs, and Option (c) is often used for severe exposure conditions or foundations, but the standard baseline for columns is 40mm.
The strirrups most commonly used in building in Mizoram is:
A)
3 legged
B)
2 legged
C)
4 legged
D)
1 legged
In reinforced concrete construction, stirrups are used to resist shear forces and hold the longitudinal reinforcement in place. A '2-legged stirrup' is the most standard and common configuration used in residential and commercial building beams and columns. It consists of a single loop of steel that wraps around the longitudinal bars, creating two vertical 'legs' that intersect the shear plane. While 4-legged or multi-legged stirrups are used in heavy-duty industrial structures or areas with extremely high shear stress, the vast majority of standard building construction in Mizoram (and generally across India following IS 456 standards) utilizes 2-legged stirrups for typical structural members. A 1-legged stirrup is not a standard structural configuration for shear reinforcement.
Flexible pavement are those which on the whole have:
A)
High flexural strength
B)
Low flexural strength
C)
High rigidity
D)
Good compressibility
In highway engineering, pavements are classified into two main types: Flexible and Rigid.
1. **Flexible Pavements** (e.g., bituminous roads) are composed of a series of layers (surface, base, sub-base, and subgrade). They lack significant structural stiffness and have **low flexural strength**. Consequently, they cannot resist bending moments; instead, they transfer the wheel load to the lower layers through grain-to-grain contact (vertical pressure distribution). They deform under load and recover (to an extent), hence the term 'flexible'.
2. **Rigid Pavements** (e.g., concrete roads) are made of Portland cement concrete. They possess **high flexural strength** and **high rigidity**, allowing them to act as a slab that distributes the load over a wide area of the subgrade through slab action.
Evaluating the options:
- **Option a (High flexural strength):** Incorrect. This is a characteristic of rigid pavements.
- **Option b (Low flexural strength):** Correct. Flexible pavements cannot resist bending and rely on the strength of the underlying layers.
- **Option c (High rigidity):** Incorrect. This is the defining characteristic of rigid pavements.
- **Option d (Good compressibility):** Incorrect. While flexible pavements are more deformable than rigid ones, 'good compressibility' is not a desired engineering property for a pavement structure, as excessive compression leads to rutting and failure.
For Single lane pavement having curve radius between 21 to 60m, the extra width provided for Single lane pavement for curve radius between 21 to 60m is:
A)
0.6m
B)
0.45m
C)
0..7m
D)
1.2m
In Highway Engineering, 'Extra Widening' is provided on horizontal curves to compensate for the off-tracking of the rear wheels of the vehicle and to provide a psychological comfort to the driver. The total widening (W) is the sum of Mechanical Widening (Wm) and Psychological Widening (Wp).
According to the Indian Roads Congress (IRC) guidelines for single-lane pavements:
1. For curves with a radius (R) greater than 175m, no extra widening is generally required.
2. For curves with a radius between 60m and 175m, the widening is smaller.
3. For curves with a radius between 21m and 60m, the standard recommended extra width for a single-lane pavement is 0.45m.
4. For curves with a radius less than 21m, the widening increases further (often up to 0.75m or more depending on the vehicle class).
Comparing the given options:
- 0.6m: Not the standard IRC value for this specific radius range.
- 0.45m: Correct standard value for single lane (R = 21m to 60m).
- 0.7m: Typically associated with tighter curves or double-lane requirements.
- 1.2m: Too large for a single-lane pavement in this radius range.
The desired temperature range of Bitumen when mixing is:
A)
110 degree centigrade – 120 degree centigrade
B)
150 degree centigrade – 177 degree centigrade
C)
110 degree centigrade – 130 degree centigrade
D)
160 degree centigrade – 187 degree centigrade
In Highway Engineering, the mixing temperature of bitumen is critical to ensure that the binder is fluid enough to coat the aggregate particles uniformly. For standard paving grade bitumen (such as VG-30), the mixing temperature typically ranges between 150°C and 177°C.
1. If the temperature is too low (e.g., 110°C - 130°C), the bitumen will be too viscous, leading to poor coating of aggregates and insufficient workability of the mix.
2. If the temperature is too high (exceeding 180°C-190°C), the bitumen may undergo 'thermal cracking' or oxidation (hardening), which reduces its adhesive properties and leads to premature failure of the pavement.
Option (b) represents the standard industry range for hot-mix asphalt (HMA) production. While specific temperatures can vary slightly based on the grade of bitumen used, 150°C to 177°C is the recognized authoritative range for general mixing operations in civil engineering examinations.
Finer the cement used in concrete means:
A)
Lower drying shrinkage
B)
Lower water requirement
C)
Higher drying shrinkage
D)
Lower water requirement for curing
Fineness of cement refers to the average size of the cement particles. When cement is finer, it has a larger specific surface area. This leads to several effects: 1. Rate of Hydration: Finer cement hydrates faster, leading to a quicker gain in strength and a higher heat of hydration. 2. Water Demand: Because of the increased surface area, finer cement requires more water to wet the particles and maintain workability, which contradicts option (b). 3. Drying Shrinkage: Since finer cement requires more water for a given consistency, the total volume of evaporable water in the concrete mix increases. As this excess water evaporates during the drying process, it leads to higher drying shrinkage. Therefore, finer cement results in higher drying shrinkage compared to coarser cement. Option (a) is the opposite of the truth, and option (d) is incorrect as curing water requirement is based on the hydration process and environmental conditions, not primarily on the fineness of the cement particles.
Joints in cement concrete pavement are provided:
A)
To facilitate proper curing
B)
To improve friction between tyre and pavement
C)
For ease of construction
D)
To reduce temperature stresses
Cement concrete is a rigid material with a low coefficient of thermal expansion, but over long stretches of highway, temperature variations cause significant expansion and contraction.
1. **Why Option (d) is correct:** When the temperature increases, the concrete slab expands. If there is no space for this expansion, internal compressive stresses build up, leading to 'buckling' or 'blow-ups'. Conversely, when temperatures drop, the slab contracts, creating tensile stresses that lead to uncontrolled cracking. Joints (Expansion, Contraction, and Longitudinal joints) are provided to create controlled gaps or weak planes, thereby relieving these temperature-induced stresses and preventing random cracking.
2. **Why other options are incorrect:**
- **Option (a):** Curing is the process of maintaining moisture to ensure hydration of cement; joints do not facilitate this process.
- **Option (b):** Friction (skid resistance) is improved by surface texturing (like grooving or tining), not by providing joints.
- **Option (c):** While construction joints are used to mark the end of a day's work, the primary engineering purpose of the overall jointing system in rigid pavements is stress management, not merely the 'ease' of construction.
Slump test is used for concrete to test:
A)
Water cement ratio
B)
Initial setting time
C)
Workability (consistency)
D)
Density
The Slump Test is a standard field test used to determine the workability and consistency of fresh concrete. Workability refers to the ease with which concrete can be mixed, transported, placed, and compacted without segregation.
Step-by-step reasoning:
1. **Mechanism**: A conical mold (Abrams cone) is filled with fresh concrete in layers and tamped. When the mold is lifted vertically, the concrete 'slumps' or subsides due to gravity.
2. **Measurement**: The vertical distance between the top of the mold and the displaced center of the concrete mass is measured as the 'slump value'.
3. **Interpretation**: A higher slump indicates higher fluidity (better workability), while a lower slump indicates a stiffer mix.
Why other options are incorrect:
- **a. Water cement ratio**: While the water-cement ratio significantly affects workability, the slump test does not measure the ratio itself; it measures the resulting physical property of the mix.
- **b. Initial setting time**: This is measured using the Vicat apparatus or Penetrability tests, which track the chemical hydration process over time, not the physical flow of fresh concrete.
- **d. Density**: Density is measured by weighing a known volume of hardened or fresh concrete (mass/volume), not by observing its deformation under gravity.
Water absorbtion for 1st class bricks used should not be more than
A)
12%
B)
15%
C)
20%
D)
25%
According to the Indian Standard (IS) specifications for bricks, bricks are classified based on their quality, strength, and water absorption properties. For a First Class Brick, the standard requirement is that it should not absorb more than 20% of its own dry weight when immersed in water for 24 hours.
Breakdown of classes:
1. First Class Bricks: Water absorption should not exceed 20% of dry weight. They are thoroughly burnt, have a ringing sound, and sharp edges.
2. Second Class Bricks: Water absorption should not exceed 22% of dry weight.
3. Third Class Bricks: Water absorption is generally higher and they are used for temporary structures or non-load bearing walls.
Therefore, option (c) 20% is the correct technical specification for first-class bricks.
The floor of cross drain ( culvert etc) is given longitudinal slope of:
A)
1 in 7
B)
1 in 10
C)
1 in 5
D)
1 in 20
In highway engineering, cross drainage works (such as culverts) are designed to facilitate the flow of water from one side of the road to the other. To ensure that water flows efficiently by gravity and to prevent the accumulation of silt or debris (self-cleansing velocity), a longitudinal slope (gradient) is provided to the floor of the culvert. According to standard IRC (Indian Roads Congress) guidelines and general civil engineering practice for cross drains, a longitudinal slope of 1 in 20 is typically recommended to maintain an adequate velocity of flow. Slopes like 1 in 5, 1 in 7, or 1 in 10 are generally too steep for standard culvert floors and could lead to excessive erosion of the bed material or structural instability, whereas 1 in 20 provides a balanced hydraulic gradient.
The rolling speed for rolling Bituminous concrete is:
A)
Not more than 10km/hr
B)
Between 5 – 10 km/hr
C)
Not more than 5km/hr
D)
Not more than 7km/hr
In highway engineering, specifically during the construction of Bituminous Concrete (BC) or Dense Bituminous Macadam (DBM), the rolling process is critical to achieve the required density and avoid surface irregularities. According to standard specifications (such as MORTH - Ministry of Road Transport and Highways), the rolling speed must be kept low to ensure proper compaction and to prevent the displacement of the mix. The recommended maximum speed for the rollers during the compaction of bituminous layers is typically specified as not more than 7 km/hr. Rolling at higher speeds can lead to 'shoving' (lateral movement of the mix) or uneven compaction, while excessively slow speeds may cause overheating of the mix in certain conditions. Therefore, option (d) is the standard technical requirement.
The recommended maximum height for Stone masonry retaining wall is:
A)
5.5m
B)
8.2m
C)
7m
D)
6m
In foundation and geotechnical engineering, stone masonry retaining walls are gravity walls that rely on their own weight to resist the lateral earth pressure. Due to the inherent limitations of stone masonry (such as the lack of tensile strength and the risk of sliding or overturning as height increases), there is a practical limit to their height. According to standard engineering practice and various building codes (including those often referenced in PWD manuals), the recommended maximum height for a stone masonry retaining wall is typically 6 meters. Beyond this height, the base width required to maintain stability becomes economically unfeasible and structurally risky, making reinforced concrete (RCC) cantilever walls a more appropriate choice. Therefore, option (d) 6m is the standard recommended maximum height.
When bars of two different diameters are to be spliced, the lap length should be calculated on the basis of:
A)
Larger diameter bars
B)
Both the diameters together
C)
Smaller diameter bars
D)
Diameter of standard bar.
In reinforced concrete design, a lap splice is used to transfer stress from one bar to another through the surrounding concrete via bond stress. When splicing two bars of different diameters, the capacity of the splice is limited by the bar that can transfer the least amount of force. The smaller diameter bar has a smaller surface area and a lower cross-sectional area, meaning it reaches its bond strength or yield strength sooner than the larger bar. Therefore, to ensure that the joint is safe and that the smaller bar is fully developed and capable of transferring its full design load to the larger bar, the lap length is calculated based on the diameter of the smaller bar. If the lap were calculated based on the larger bar, it would be unnecessarily long; however, the critical requirement is that the smaller bar must be sufficiently anchored to avoid pull-out or failure at the splice location.
Shallow foundation is where:
A)
Depth of foundation less than 1.5 times of width of foundation
B)
Depth of foundation less than or equal to the width of foundation
C)
Depth of foundation less than 1.5m
D)
Depth of foundation Less than 2.0m
Option B is correct: Depth of foundation less than or equal to the width of foundation.
California Bearing Ratio ( CBR) value is expressed in:
A)
mm
B)
cm
C)
% (percentage)
D)
N/mm2
The California Bearing Ratio (CBR) is a penetration test used to evaluate the subgrade strength of roads and pavements. It is defined as the ratio of the load pressure required to penetrate a soil sample with a standard piston to the load pressure required to penetrate a standard high-quality crushed stone material (standard CBR material) to the same depth.
Mathematically, it is expressed as:
CBR (%) = (Load pressure of soil / Load pressure of standard crushed stone) × 100
Because it is a ratio of two pressures (stress values) multiplied by 100, the resulting value is dimensionless and expressed as a percentage.
Analysis of other options:
- a. mm: This is a unit of length/penetration depth, not the CBR value itself.
- b. cm: This is also a unit of length.
- d. N/mm²: This is a unit of pressure (MPa). While the loads used to calculate CBR are measured in pressure units, the final CBR value is the ratio of these pressures, making it a percentage.
Which of the following is not Rigid pavement?
A)
Plain concrete
B)
Reinforced concrete
C)
Asphaltic concrete
D)
Pre-stressed concrete
In highway engineering, pavements are broadly classified into two types based on their structural behavior: Rigid Pavements and Flexible Pavements.
1. Rigid Pavements: These are constructed using cement concrete. They possess a high modulus of elasticity and high flexural strength, allowing them to distribute the wheel load over a wide area of the subgrade through slab action. Examples include:
- Plain Jointed Concrete Pavement (PJP)
- Reinforced Concrete Pavement (RCP)
- Pre-stressed Concrete Pavement (PCP)
2. Flexible Pavements: These are constructed using bituminous materials. They have low flexural strength and transmit the load to the subgrade layer-by-layer through grain-to-grain contact.
Analysis of Options:
- Option (a) Plain concrete: A standard type of rigid pavement.
- Option (b) Reinforced concrete: A type of rigid pavement where steel is added to control cracking.
- Option (c) Asphaltic concrete: This is a mixture of asphalt binder and aggregates. It is the primary material used for flexible pavements, not rigid pavements.
- Option (d) Pre-stressed concrete: An advanced type of rigid pavement used to reduce thickness and increase durability.
Therefore, Asphaltic concrete is not a rigid pavement.
The recommended values of Camber for different This Bituminous road surface in Heavy rainfall areas is:
A)
2.5%
B)
3.0%
C)
1.7%
D)
4.0%
Camber (or cross-slope) is provided on the road surface to drain off rainwater from the pavement to the side drains, preventing water logging and protecting the road structure. The recommended values for camber depend on the type of road surface and the intensity of rainfall. According to IRC (Indian Roads Congress) guidelines:
1. Concrete/Cement Concrete roads: Heavy rainfall (1.7% to 2.0%), Light rainfall (1.7%).
2. Bituminous/Water Bound Macadam (WBM) roads: Heavy rainfall (2.5%), Medium rainfall (2.0%), Light rainfall (1.5%).
3. Earthen roads: Heavy rainfall (4.0%), Medium rainfall (3.0%), Light rainfall (2.0%).
In this specific question, the road surface is 'Bituminous' and the area is 'Heavy rainfall'. Therefore, the recommended camber value is 2.5%.
- Option b (3.0%) is for Earthen roads in medium rainfall.
- Option c (1.7%) is for Concrete roads.
- Option d (4.0%) is for Earthen roads in heavy rainfall.
If the water absorption of aggregates to be used for WMM and WBM exceed 2%, which of the following test is to be conducted?
A)
AIV test
B)
Los Angeles abrasion value test
C)
Soundness test
D)
Specific gravity test
For aggregates used in WMM/WBM, if water absorption exceeds 2%, a soundness test is required to assess the aggregate’s resistance to weathering action due to repeated wetting and drying. High water absorption indicates a more porous aggregate, which may be less durable in service, so soundness becomes critical.
Why the others are incorrect:
- Los Angeles abrasion value test (b): measures resistance to abrasion and impact, not water absorption-related durability.
- Specific gravity test (d): determines density/relative density of aggregates, not their durability under weathering.
- AIV test (a): Aggregate Impact Value test measures resistance to sudden impact, not the effect of high water absorption.
Hence, the correct answer is c) Soundness test.
The most common material used for septic tank construction is:
A)
Timber
B)
Steel sheet
C)
RCC
D)
Plastic
A septic tank is an underground anaerobic digestion chamber that must be completely watertight to prevent groundwater contamination and withstand external soil pressure.
1. **RCC (Reinforced Cement Concrete)**: This is the most common material because it provides the necessary structural strength to resist earth pressure, is naturally impermeable (when properly cast), and is highly durable against the corrosive gases (like Hydrogen Sulfide) produced during the decomposition of sewage.
2. **Timber**: This is unsuitable as it decays rapidly in moist, underground environments and is not watertight.
3. **Steel sheet**: While strong, steel is highly susceptible to corrosion due to the acidic nature of sewage and the moist soil environment, making it impractical for long-term underground use.
4. **Plastic**: While some prefabricated plastic tanks exist for small-scale residential use, RCC remains the standard and most common material for general engineering construction of septic tanks due to its longevity and load-bearing capacity.
Black smoke from a diesel engine indicates:
A)
excess air supply
B)
proper combustion
C)
incomplete combustion
D)
low fuel supply
In a diesel engine, black smoke is primarily composed of unburnt carbon particles (soot). This occurs when there is an insufficient supply of oxygen to completely oxidize the fuel injected into the cylinder, or when the fuel is not atomized properly. This condition is known as 'incomplete combustion'.
Analysis of options:
- (a) Excess air supply: This would lead to leaner combustion and typically results in clear exhaust or, in some cases, white/blue smoke if oil is leaking, but not black smoke.
- (b) Proper combustion: Ideal combustion results in colorless or nearly colorless exhaust gases (mostly CO2, H2O, and N2).
- (c) Incomplete combustion: Correct. A rich fuel-to-air ratio (too much fuel or too little air) prevents the carbon in the fuel from burning completely, resulting in black soot.
- (d) Low fuel supply: This would lead to a lean mixture, which generally prevents the formation of black smoke and may cause the engine to lose power or stall.
Multistage centrifugal pumps are used to obtain:
A)
high discharge
B)
high head
C)
pumping of viscous fluids
D)
high head and high discharge
A centrifugal pump is a kinetic machine that converts rotational energy into pressure energy. The head (pressure) developed by a single-stage centrifugal pump is limited by the impeller diameter and the rotational speed. To achieve a higher head without increasing the speed to impractical levels or making the impeller excessively large, multiple impellers are arranged in series. In a multistage centrifugal pump, the discharge of the first stage becomes the suction for the second stage, and so on. Consequently, the total head produced is the sum of the heads produced by each individual stage (Total Head = n × Head per stage, where n is the number of stages).
Why other options are incorrect:
- (a) High discharge: To increase discharge (flow rate), pumps are typically arranged in parallel, or a larger impeller diameter is used in a single stage.
- (c) Pumping of viscous fluids: Centrifugal pumps are generally inefficient for high-viscosity fluids; positive displacement pumps are used for that purpose.
- (d) High head and high discharge: While some pumps can do both, the specific defining purpose of 'multistaging' (series arrangement) is specifically to increase the head.
HDPE pipes are preferred because they are:
A)
Corrosion resistant
B)
Brittle
C)
Heavy
D)
Expensive
High-Density Polyethylene (HDPE) pipes are widely preferred in public health engineering and water distribution systems due to several key material properties:
1. **Corrosion Resistance (Correct):** HDPE is a chemically inert thermoplastic. Unlike metallic pipes (such as cast iron or galvanized steel), it does not rust or corrode when exposed to moisture, soil chemicals, or various corrosive fluids. This significantly increases the lifespan of the piping system and reduces maintenance costs.
2. **Ductility vs. Brittleness (Incorrect):** HDPE is known for its flexibility and toughness. It is the opposite of 'brittle'; it can withstand significant deformation and ground movement without cracking.
3. **Weight (Incorrect):** HDPE is lightweight compared to concrete or metal pipes, making it easier and cheaper to transport and install.
4. **Cost (Incorrect):** While initial material costs vary, HDPE is generally considered cost-effective over its lifecycle due to lower installation costs (fewer joints) and lack of need for expensive anti-corrosion coatings.
The minimum residual chlorine recommended in drinking water is:
A)
0.01 mg/L
B)
1.5 mg/L
C)
0.2 mg/L
D)
5 mg/L
Chlorination is used in water treatment to eliminate pathogenic microorganisms. After the initial 'chlorine demand' of the water is met (where chlorine reacts with organic matter and impurities), the remaining chlorine is known as 'residual chlorine'. This residual is essential to protect the water from re-contamination during distribution through the pipeline network. According to standard public health engineering guidelines (including WHO and various national standards like IS 10500), the recommended minimum free residual chlorine in drinking water at the consumer's tap is 0.2 mg/L after a contact time of 30 minutes.
Analysis of options:
- a. 0.01 mg/L: Too low to provide any meaningful protection against re-contamination.
- b. 1.5 mg/L: This is higher than the minimum requirement and may lead to an unpleasant taste and odor (chlorine taste).
- c. 0.2 mg/L: The standard minimum recommended residual for safe drinking water.
- d. 5 mg/L: This is an excessively high concentration, typically used only for shock chlorination or disinfection of new pipes, and is not suitable for regular drinking water.
Which of the following is a pipe appurtenance?
A)
Beam
B)
Sluice valve
C)
Column
D)
Slab
In piping and hydraulic engineering, 'pipe appurtenances' refer to the fittings, valves, and accessories attached to a pipeline to control flow, regulate pressure, provide access, or facilitate maintenance.
1. **Sluice valve (Gate valve):** This is a primary pipe appurtenance used to completely stop or allow the flow of water within a pipe. It is a standard component in water distribution networks.
2. **Beam:** This is a structural member used in civil engineering to carry transverse loads; it is not part of a piping system.
3. **Column:** This is a vertical structural member used to support loads in buildings or bridges; it is not a pipe appurtenance.
4. **Slab:** This is a flat, horizontal structural element (like a floor or roof) made of concrete or other materials; it is not a pipe appurtenance.
Therefore, the sluice valve is the only option that fits the definition of a pipe appurtenance.