GATE Technical: Civil Engineering (Set 2) questions with solutions

Q1. The setting time of cement is determined using

1. Le Chatelier apparatus
2. Briquette testing apparatus
3. Vicat apparatus
4. Casagrande’s apparatus

Answer: Vicat apparatus

The Vicat apparatus is specifically designed to measure the setting time of cement by determining the penetration of a needle into the cement paste, allowing for precise assessment of its initial and final setting times.

Q2. Which one of the following statements is NOT correct?

1. When the water content of soil lies between its liquid limit and plastic limit, the soil is said to be in plastic state.
2. Boussinesq's theory is used for the analysis of stratified soil.
3. The inclination of stable slope in cohesive soil can be greater than its angle of internal friction.
4. For saturated dense fine sand, after applying overburden correction, if the Standard Penetration Test value exceeds 15, dilatancy correction is to be applied.

Answer: Boussinesq's theory is used for the analysis of stratified soil.

Boussinesq's theory is primarily used to analyze the stress distribution in homogeneous, isotropic soil rather than stratified soil, making the statement incorrect.

Q3. The clay mineral, whose structural units are held together by potassium bond is

1. Halloysite
2. Illite
3. Kaolinite
4. Smectite

Answer: Illite

Illite is a clay mineral characterized by its layered structure, where potassium ions play a crucial role in holding the structural units together, providing stability and influencing its properties.

Q4. Dupuit's assumptions are valid for

1. artesian aquifer
2. confined aquifer
3. leaky aquifer
4. unconfined aquifer

Answer: unconfined aquifer

Dupuit's assumptions are valid for unconfined aquifers because they simplify the flow of groundwater by assuming that the water table is free to rise and fall, which is characteristic of unconfined conditions where the aquifer is directly open to the atmosphere.

Q5. For a given discharge in an open channel, there are two depths which have the same specific energy. These two depths are known as

1. alternate depths
2. critical depths
3. normal depths
4. sequent depths

Answer: alternate depths

Alternate depths refer to the two different depths in an open channel flow that yield the same specific energy for a given discharge, highlighting the relationship between flow depth and energy.

Q6. As per IS 10500:2012, for drinking water in the absence of alternate source of water, the permissible limits for chloride and sulphate, in mg/L, respectively are

1. 250 and 200
2. 1000 and 400
3. 200 and 250
4. 500 and 1000

Answer: 500 and 1000

The correct option is right because IS 10500:2012 specifies that the permissible limits for chloride and sulphate in drinking water are set at 500 mg/L and 1000 mg/L, respectively, to ensure safety and health standards for consumption.

Q7. In the figures, Group I represents the atmospheric temperature profiles (P, Q, R and S) and Group II represents dispersion of pollutants from a smoke stack (1, 2, 3 and 4). In the figures of Group I, the dashed line represents the dry adiabatic lapse rate, whereas the horizontal axis represents temperature and the vertical axis represents the altitude. Group I: P Superadiabatic; Q Adiabatic; R Inversion; S Inversion over superadiabatic Group II: 1 Looping plume; 2 Coning plume; 3 Fanning plume; 4 Fumigation The correct match is

1. (A) P-1, Q-2, R-3, S-4
2. (B) P-1, Q-2, R-4, S-3
3. (C) P-1, Q-4, R-3, S-2
4. (D) P-3, Q-1, R-2, S-4

Answer: (A) P-1, Q-2, R-3, S-4

Standard plume matching: superadiabatic->looping(1), adiabatic->coning(2), inversion->fanning(3), inversion over superadiabatic->fumigation(4). This is option A (P-1,Q-2,R-3,S-4), not the stored option B.

Q8. Peak Hour Factor (PHF) is used to represent the proportion of peak sub-hourly traffic flow within the peak hour. If 15-minute sub-hours are considered, the theoretically possible range of PHF will be

1. (A) 0 to 1.0
2. (B) 0.25 to 0.75
3. (C) 0.25 to 1.0
4. (D) 0.5 to 1.0

Answer: (C) 0.25 to 1.0

The Peak Hour Factor (PHF) quantifies the variability of traffic flow within a peak hour, and since it is based on the ratio of the total flow to the maximum flow in any 15-minute sub-period, it can theoretically range from 0.25 (indicating very uneven distribution) to 1.0 (indicating uniform distribution).

Q9. A level instrument at a height of 1.320 m has been placed at a station having a Reduced Level (RL) of 112.565 m. The instrument reads -2.835 m on a levelling staff held at the bottom of a bridge deck. The RL (in m) of the bottom of the bridge deck is

1. 116.720
2. 116.080
3. 114.080
4. 111.050

Answer: 116.720

Height of collimation = 112.565 + 1.320 = 113.885 m. The bridge soffit is above the line of sight, giving the inverted (negative) staff reading, so RL = 113.885 - (-2.835) = 116.720 m, which is option index 0, not the stored 116.080.