GATE Technical: Civil Engineering (CE2) questions with solutions

Q1. Consider the following statements (P) and (Q): (P): Fly ash and ground granulated blast furnace slag can be used as mineral admixtures in concrete. (Q): As per IS 456:2000, the minimum moist curing period becomes higher when a mineral admixture is added to concrete. Identify the CORRECT option from choices given below.

1. Both (P) and (Q) are TRUE.
2. (P) is TRUE and (Q) is FALSE.
3. (P) is FALSE and (Q) is TRUE.
4. Both (P) and (Q) are FALSE.

Answer: Both (P) and (Q) are TRUE.

Both statements are accurate; fly ash and ground granulated blast furnace slag are indeed recognized as mineral admixtures that enhance concrete properties, and IS 456:2000 specifies that the curing period should be extended when such admixtures are used to ensure proper hydration and strength development.

Q2. The bacteria mainly responsible for crown corrosion in a sewer is ______.

1. Methanogenic bacteria
2. Denitrifying bacteria
3. Sulphur reducing bacteria
4. Pseudomonas bacteria

Answer: Sulphur reducing bacteria

Sulphur reducing bacteria are primarily responsible for crown corrosion in sewers because they produce hydrogen sulfide, which can lead to the deterioration of concrete and other materials in sewer systems.

Q3. The recommended minimum traffic growth rate and design period considered for structural design of flexible pavements for national highways in India as per IRC 37:2018 is ______ percentage and ______ years, respectively.

1. 5, 20
2. 5, 30
3. 7, 20
4. 7, 30

Answer: 5, 20

The correct option specifies a minimum traffic growth rate of 5% and a design period of 20 years, which aligns with the guidelines set by IRC 37:2018 for ensuring the structural integrity and longevity of flexible pavements on national highways.

Q4. After applying the correction for elevation and temperature, the runway length is 700 m. The corrected runway length (in m) for an effective gradient of 1% is ______ (round off to the nearest integer).

1. 840
2. 700
3. 720
4. 740

Answer: 840

The corrected runway length accounts for the effective gradient, which increases the required length for safe takeoff and landing. A 1% gradient necessitates an increase in length to ensure performance standards are met, resulting in a total of 840 m.

Q5. The point where the road alignment changes from a tangent to a curve is known as _______.

1. Point of deflection
2. Point of intersection
3. Point of curve
4. Point of tangency

Answer: Point of curve

The point of curve is where the road transitions from a straight section (tangent) to a curved section, marking the beginning of the curve.

Q6. Consider a velocity vector, V in (x, y, z) coordinates given below. Pick one or more CORRECT statement(s) from the choices given below. V = ux̂ + vŷ

1. z-component of Curl of velocity: ∇ × V = ((∂ v)/(∂ x) - (∂ u)/(∂ y))ẑ
2. z-component of Curl of velocity: ∇ × V = ((∂ u)/(∂ x) - (∂ v)/(∂ y))ẑ
3. Divergence of velocity: ∇ · V = ((∂ u)/(∂ x) + (∂ v)/(∂ y))
4. Divergence of velocity: ∇ · V = ((∂ u)/(∂ y) + (∂ v)/(∂ x))

Answer: z-component of Curl of velocity: ∇ × V = ((∂ v)/(∂ x) - (∂ u)/(∂ y))ẑ

The correct option accurately represents the z-component of the curl of a two-dimensional velocity vector field, which is defined as the difference between the partial derivative of the y-component with respect to x and the partial derivative of the x-component with respect to y.

Q7. Given that A and B are not null sets, which of the following statements regarding probability is/are CORRECT?

1. P(A∩B) = P(A) P(B), if A and B are mutually exclusive.
2. Conditional probability, P(A|B) = 1, if B ⊂ A.
3. P(A∪B) = P(A) + P(B), if A and B are mutually exclusive.
4. P(A∩B) = 0, if A and B are independent.

Answer: P(A∪B) = P(A) + P(B), if A and B are mutually exclusive.

The statement is correct because when two events A and B are mutually exclusive, they cannot occur at the same time, which means the probability of their union is simply the sum of their individual probabilities.

Q8. In the context of construction materials, which of the following statements is/are CORRECT?

1. If the characteristic strength is defined as that value below which not more than 50% results are expected to fall, the target mean strength in mix design will be taken same as the characteristic strength irrespective of the degree of quality control expected at the site.
2. Ten percent fines value is a non-dimensional quantity.
3. The stress-strain curve of concrete for 1-day duration of loading is associated with a smaller secant modulus of elasticity compared to the stress-strain curve of the same concrete for 10-minutes duration of loading.
4. The increase of carbon in steel usually leads to an increase in its 0.2% proof stress.

Answer: The increase of carbon in steel usually leads to an increase in its 0.2% proof stress.

Increasing the carbon content in steel enhances its hardness and strength, which directly contributes to a higher 0.2% proof stress, making it more resistant to deformation under load.

Q9. Which of the following statements is/are INCORRECT?

1. As the depth of the ground water table from the ground surface increases, the effective stress in the soil decreases.
2. Bulking of the moist sand is due to the capillary action in the sand.
3. The effective stress in a liquified soil is almost zero.
4. The earth pressure at any point in the soil, under all conditions, is always smaller than the vertical effective stress at that point.

Answer: The earth pressure at any point in the soil, under all conditions, is always smaller than the vertical effective stress at that point.

The statement about earth pressure is correct because, under normal conditions, the total stress in the soil includes both effective stress and pore water pressure, meaning that the earth pressure cannot exceed the vertical effective stress.

Q10. Pick one or more CORRECT statement(s) from the choices given below, in the context of upstream and downstream cut-offs provided below the concrete apron of weirs/barrages constructed across alluvial rivers.

1. Cut-offs are provided to increase the rate of flow over the weir/barrage.
2. Cut-offs are provided to increase the seepage length and prevent failure due to piping.
3. The bottom level of cut-offs mainly depends on the scour depth.
4. Cut-offs are provided to ensure occurrence of hydraulic jump within the stilling basin.

Answer: Cut-offs are provided to increase the seepage length and prevent failure due to piping.

Cut-offs are designed to enhance the seepage path, which helps to reduce the risk of piping failures by ensuring that water does not easily erode the soil beneath the structure. This is crucial for maintaining the stability and integrity of the weir or barrage.

Q11. Identify the treatment technology/technologies NOT recommended for highly biodegradable organic solid wastes.

1. Biohydrogenation
2. Anaerobic digestion
3. Composting
4. Open dumping

Answer: Open dumping

Open dumping is not a recommended treatment technology for highly biodegradable organic solid wastes because it poses significant environmental and health risks, such as pollution and the attraction of pests, rather than effectively managing or processing the waste.

Q12. In the context of shear strength of soil, which of the following statements is/are CORRECT?

1. The unconfined compression test is a special case of the unconsolidated-undrained (UU) triaxial tests.
2. The shear strength parameters obtained from the consolidated-drained (CD) triaxial tests should be used to analyse rapid construction in clay.
3. Vane shear test is commonly used for determining in situ undrained strength of saturated clay soils.
4. In an unconsolidated-undrained (UU) triaxial tests, the angle of internal friction (ϕ) is equal to zero.

Answer: Vane shear test is commonly used for determining in situ undrained strength of saturated clay soils.

The vane shear test is specifically designed to measure the undrained shear strength of saturated clay in situ, making it a reliable method for assessing the strength of soft clays under undrained conditions.

Q13. The drag force, F_D on a sphere due to a fluid flowing past the sphere is a function of viscosity, μ, the mass density, ρ, the velocity of flow, V, and the diameter of the sphere, D. Pick the relevant (one or more) non-dimensional parameter(s) pertaining to the above process from the following list.

1. F_D/(ρV²D²)
2. ρF_D/(V²D²)
3. ρVD/μ
4. μρ/(VD)

Answer: F_D/(ρV²D²)

The correct option, F_D/(ρV²D²), is a non-dimensional parameter known as the drag coefficient, which helps to characterize the drag force on the sphere relative to the inertial forces acting on it, making it essential for comparing different flow conditions.

Q14. A compound has general formula C_aH_bO_cN_d and molecular weight 187. A 935 mg/L solution of the compound is prepared in distilled deionized water. The Total Organic Carbon (TOC) is measured as 360 mg/L (as C). The Chemical Oxygen Demand (COD) and the Total Kjeldahl Nitrogen (TKN) are determined as 800 mg/L (as O2) and 140 mg/L (as N), respectively (as per the chemical equation given below). Which of the following options is/are CORRECT? C_aH_bO_cN_d + ((4a+b-2c-3d)/4) O2 -> aCO2 + ((b-3d)/2) H2O + dNH3 Atomic weight: C(12), H(1), O(16), N(14)

1. a = 6
2. b = 7
3. c = 5
4. d = 3

Answer: a = 6

The correct option a = 6 is right because it satisfies the molecular weight of the compound when calculated using the general formula and the provided atomic weights. Substituting a = 6 into the equation allows for the correct balancing of carbon, hydrogen, oxygen, and nitrogen, aligning with the total molecular weight of 187.

Q15. The free flow speed of a highway is 100 km/h and its capacity is 4000 vehicle/h. A speed density relation is linear. For a traffic volume of 2000 vehicle/h, choose all the possible speeds (in km/h) from the options given below (round off to two decimal places).

1. 85.36
2. 65.20
3. 14.64
4. 7.22

Answer: 85.36

The correct option, 85.36 km/h, is derived from the linear speed-density relationship, where at a traffic volume of 2000 vehicle/h, the speed can be calculated by considering the maximum speed and capacity. This speed is within the range that maintains a stable flow without exceeding the capacity.