SSC-JUNIOR ENGINEER (Civil & Structural) Online Exam 2020 (Exam held on 23/03/2021) (Part-III)

GENERAL ENGINEERING CIVIL AND  STRUCTURAL

Total Questions: 50

1. What will be the percentage of passing aggregate for the grading zone 1 of sieve size 1.18 mm?

Correct Answer: C. 30%-70%
Solution:The sieve analysis of aggregate determines the % of sizes of aggregates in the sample and hence packing as well as mix design ratios for a concrete mix can be derived.

The sieve analysis of aggregates shows the gradation curve of various sizes of aggregates in the given sample

IS Sieve DesignationGrading Zone 1 (in %)Grading Zone 2 (in %)Grading Zone 3 (in %)Grading Zone 4 (in %)
10 mm100100100100
4.75 mm90–10090–10090–10095–100
2.36 mm60–9575–10085–10095–100
1.18 mm30–7055–9075–10090–100

2. Activity of soil is ratio of the plasticity index to:

Correct Answer: D. percentage by weight of clay fraction
Solution:No explanation given in the book

3. Read the question given below :

Correct Answer: B.
Solution:As per IS 456:2000, the modulus of elasticity of concrete is given by:

Where θ is the creep coefficient depending upon the age of the concrete

Age at loadingValue of creep coefficient (θ)
7 days2.2
28 days1.6
1 year1.1

4. According to IS 456-2000, what is the slump of a medium degree of workability of concrete if placed in heavily reinforced sections like slabs, beams, walls, columns?

Correct Answer: B. 50-100 mm
Solution:

5. Which of the following methods is NOT used for measuring air content in fresh concrete?

Correct Answer: A. Blaine air permeability method
Solution:Blaine air permeability apparatus is used for determining the fineness of Portland cement measures the specific surface area of fine materials in square centimeters per gram of test sample. By using this apparatus, a quantity of air is drawn through a bed of definite porosity. The rate of airflow is determined by the pore volume in the bed, a function of the size of particles.

6. The following statements (C1, C2, C3, C4) pertain to the characteristics of different types of canals. Which of the following statements is/are correct?

C1: A contour canal can irrigate command areas on both the banks.

C2: It is possible to construct a contour canal with banks on one side only.

C3: In the case of a ridge canal, the number of cross drainage works are maximum.

C4: Side slope canal is aligned roughly at right angles to the ground contours.

Correct Answer: C. C2 and C4 only
Solution:Statement C1: In contour canal the river slope is much steeper than the canal bed slope so therefore the canal encloses more and more area between itself and the river. It should be noted that more fertile lands are located at the lower levels. In other words, we can say contour canal irrigates only on one side as the other side is higher.

Statement C2: A contour canal aligned roughly parallel to the contours of the area is called a contour canal. This type of canal can be seen in hilly regions. Since it is parallel to the contour line, the ground on one side of the canal is higher and hence irrigation is possible only on the other side of the canal. A contour canal has to pass the drainage and hence cross drainage works are required to be provided.

Statement C3: A Ridge canal aligned along the ridgeline or watershed line of an area is said to be ridge canal or watershed canal. Since it is running at the peak altitude of the area, irrigation on both sides of the canal up to a larger extent of the area is possible. There is no interception of natural drains on ridge lines hence, no cross drainage works are required for this type of canal.

Statement C4: A side slope canal aligned nearly perpendicular to the contour of the area. It is located neither on the ridgeline nor on the valley line but is approximately in between them. It is parallel to the natural drainage line and hence no cross drainage works are required. The bed slope of side slope canal is very steep.

7. In a workshop shade, trusses are spaced at 4 m centre to centre. The purlins are spaced at 1.4 m centre to centre along the slope of 30°. The (Dead Load + Live Load) is 3 kN/m² and the wind load is 5 kN/m². The vertical and the inclined point loads, respectively, will be:

Correct Answer: D. 14.54 kN and 28 kN
Solution:Area of the shade = 1.4 m x 4 m = 5.6 m²

8. Arrange the following building materials in the increasing order of density of materials.

Granite, Steel, River sand, Water

Correct Answer: C. Water, River sand, Granite, Steel
Solution:Increasing order of density (in Kg/m³) of building material:
Water (1000) < River Sand (2000) < Granite (2691) Steel (7850).

9. What will be the carrying capacity of a horizontal rectangular channel 4 m wide, conveying a discharge of 1 cumecs per meter width of channel?

Correct Answer: C. 4.000 m³/s
Solution:1 m rectangular channel conveying a discharge of 1 cumec = 1 m³/sec
∴ 4 m rectangular channel conveying a discharge = 4 × 1 = 4m³ /sec.

10. The test commonly adopted to determine the grade of bitumen in terms of its hardness is:

Correct Answer: D. the penetration test
Solution:Bituminous materials are used in highway construction primarily because of their binding and water proofing properties.
The penetration of test determines the hard-ness or softness of bitumen by measuring the depth in tenths of a millimetre to which a standard loaded needle will penetrate vertically in five seconds.

In hot climates, a lower penetration grade bitumen like 30/40 bitumen is preferred.
Generally higher softening point indicates lower temperature susceptibility and is preferred in warm climates.
For bitumen, higher the penetration value lower is the softening point.