GATE Technical: Civil Engineering (CE1) questions with solutions

Q1. Identify the FALSE statement from the following options:

1. The compressive strength of a concrete test specimen can vary depending on its shape and size
2. Air-dried and saturated test specimens show the same compressive strength for concrete
3. Curing conditions, such as temperature and relative humidity, can influence the compressive strength of concrete
4. Compressive strength depends on the water-to-binder ratio used in the concrete mixture

Answer: Air-dried and saturated test specimens show the same compressive strength for concrete

Air-dried and saturated test specimens do not exhibit the same compressive strength because the moisture content significantly affects the concrete's properties; saturated specimens generally demonstrate higher strength due to better hydration of the cement.

Q2. The results of a consolidated drained triaxial test on a normally consolidated clay are shown in the figure. The angle of internal friction is

1. sin⁻¹(1/2)
2. sin⁻¹(1/3)
3. sin⁻¹(2/3)
4. sin⁻¹(3/4)

Answer: sin⁻¹(1/3)

The angle of internal friction for normally consolidated clay can be derived from the effective stress parameters shown in the test results, where the correct value corresponds to the ratio of the effective stress components, leading to sin⁻¹(1/3) as the accurate representation.

Q3. To derive the total flood hydrograph at a catchment outlet from an isolated storm, the order in which the following methods are applied, from the first method to the last method, is P. Obtaining the hyetograph Q. Addition of baseflow R. Estimation of initial and infiltration losses S. Application of unit hydrograph

1. P R S Q
2. P Q R S
3. R P S Q
4. P S Q R

Answer: P R S Q

The correct order begins with obtaining the hyetograph to visualize rainfall data, followed by estimating initial and infiltration losses to determine effective rainfall. Next, the unit hydrograph is applied to convert effective rainfall into runoff, and finally, baseflow is added to obtain the total flood hydrograph.

Q4. A hydrocarbon (C_nHₘ) is burnt in air (O₂ + 3.78N₂). The stoichiometric fuel to air mass ratio for this process is Note: Atomic Wt. C (12), H (1) Effective Molecular Wt. Air (28.8) Ignore any conversion of N₂ in air to the oxides of nitrogen (NOₓ)

1. 0.0291 ((4n + m)/(12n + m))
2. 34.42 ((12n + m)/(4n + m))
3. 34.42 ((4n + m)/(12n + m))
4. 0.0291 ((12n + m)/(4n + m))

Answer: 0.0291 ((12n + m)/(4n + m))

The correct option is derived from the stoichiometric calculations of the combustion process, where the mass of the hydrocarbon is compared to the mass of the air required for complete combustion. The formula reflects the relationship between the molecular weights of the components involved, ensuring that the fuel-to-air ratio is accurately represented.

Q5. All the vehicles that come during a particular peak hour come during a 10-minute period within this hour. The 15-minute peak hour factor for this peak hour is

1. 0.25
2. 0.167
3. 0.75
4. 1.0

Answer: 0.25

All vehicles arrive in a 10-min window inside the hour, so the busiest 15 min already contains the entire hourly volume V. PHF = V/(4 x peak-15min) = V/(4V) = 0.25, so the stored 1.0 is wrong.

Q6. In the context of testing bitumen, which one of the following statements is FALSE:

1. The depth of penetration of needle in the standard penetration test is measured in the units of one-tenth of millimeter
2. Softening point is measured using a ring and ball apparatus
3. Softening point is measured in the units of time
4. Ductility is measured in the units of length

Answer: Softening point is measured in the units of time

The statement is incorrect because the softening point of bitumen is measured in degrees Celsius, not in units of time. This measurement indicates the temperature at which the bitumen softens enough to flow.

Q7. If the horizontal distance between a staff point and the point of observation is d, the error due to the curvature of earth is proportional to

1. d
2. 1/d
3. d²
4. 1/d²

Answer: d²

The error due to the curvature of the Earth increases with the square of the distance because the curvature affects the line of sight more significantly as the distance increases, leading to a quadratic relationship.

Q8. Consider the frame shown in the figure under the loading of 100 kN.m couples at the joints B and G. Considering only the effects of flexural deformations, which of the following statements is/are true:

1. Axial force is zero in the member CD
2. Shear force is zero in the member CD
3. There is no rotation in the joint C
4. The magnitude of bending moment developed in the member BC at the end C is more than 50 kN.m

Answer: The magnitude of bending moment developed in the member BC at the end C is more than 50 kN.m

The statement is correct because the application of couples at joints B and G induces bending moments in the members of the frame, particularly in member BC, resulting in a bending moment greater than 50 kN.m at end C.

Q9. For the Bernoulli's equation to be applicable in a fluid flow situation, which of the following conditions is/are to be satisfied:

1. Fluid should be frictionless
2. Fluid should be incompressible
3. Flow should be steady
4. Flow should be rotational

Answer: Fluid should be frictionless

Bernoulli's equation assumes that the fluid has no viscosity, meaning it behaves as a frictionless fluid. This allows for the conservation of mechanical energy along a streamline, which is a fundamental aspect of the equation.

Q10. A aeration is employed as a treatment option for the removal of several pollutants from contaminated water. Identify the pollutant(s), where aeration is employed as a part of their removal:

1. Iron
2. Cadmium
3. Manganese
4. Zinc

Answer: Iron

Aeration is effective in removing iron from contaminated water because it oxidizes dissolved ferrous iron (Fe2+) into ferric iron (Fe3+), which then precipitates out as solid particles that can be filtered out.

Q11. In the rigid-jointed frame shown in the figure, the distribution factor of the member AD is closest to

1. 0.254
2. 0.267
3. 0.398
4. 0.421

Answer: 0.267

The distribution factor for a member in a rigid-jointed frame is calculated based on the relative stiffness of that member compared to the total stiffness of the joint. In this case, the value of 0.267 indicates that member AD has a significant proportion of the joint's stiffness, reflecting its contribution to the overall structural behavior.

Q12. The mean rainfall over a catchment has to be estimated. The data for four rain gauges located in and around the catchment is listed in the table. Which one of the following statements is correct: Rain gauge station: P, Q, R, S Whether located inside the catchment: Yes, Yes, Yes, No Thiessen weightage factor: 0.25, 0.50, 0.10, 0.15 Rainfall (mm): 100, 110, 100, 125

1. The estimate obtained from the Thiessen-mean method is greater than that obtained using the arithmetic-mean method
2. The estimate obtained from the Thiessen-mean method is equal to that obtained using the arithmetic-mean method
3. The estimate obtained from the Thiessen-mean method is less than that obtained using the arithmetic-mean method
4. The Thiessen-mean method cannot be applied in this case

Answer: The estimate obtained from the Thiessen-mean method is equal to that obtained using the arithmetic-mean method

Thiessen mean = 0.25*100 + 0.50*110 + 0.10*100 + 0.15*125 = 25+55+10+18.75 = 108.75 mm. Arithmetic mean = (100+110+100+125)/4 = 435/4 = 108.75 mm. The two estimates are exactly equal.

Q13. The speed-density relation on a one-way, single lane road is shown in the figure, where speed u is in km/hour and density k is in vehicles/km. The maximum flow (in vehicles/hour) on this road is

1. 2500
2. 900
3. 2250
4. 2000

Answer: 2000

The maximum flow on a road is determined by the product of speed and density at the point where the flow is maximized. In this case, the speed at maximum flow is optimal at a density that yields 2000 vehicles/hour, making option D the correct choice.

Q14. In the context of construction project management, which of the following statements is/are true:

1. A dummy activity will consume time and resources
2. The programme evaluation and review technique (PERT) is best suited for projects with large uncertainties in the duration of activities
3. A Gantt chart is commonly used for identifying the ‘critical path’ of activities in a project
4. Free float is the amount of time by which the start of an activity can be delayed without causing a delay in the start of a following activity

Answer: The programme evaluation and review technique (PERT) is best suited for projects with large uncertainties in the duration of activities

PERT is designed to handle projects where activity durations are uncertain, allowing for probabilistic estimates and better risk management, making it ideal for such scenarios.

Q15. A facultative pond system is employed for wastewater treatment. Which of the following statements is/are true:

1. The dissolved oxygen concentration will be high during daytime compared to night-time
2. The pH will be high during daytime compared to night-time
3. The dissolved oxygen concentration will be low during daytime compared to night-time
4. The pH will be low during daytime compared to night-time

Answer: The dissolved oxygen concentration will be high during daytime compared to night-time

During the daytime, photosynthetic activity by aquatic plants and algae increases, leading to higher levels of dissolved oxygen in the water, while at night, respiration processes dominate, causing oxygen levels to drop.