This set of Basic Civil Engineering Interview Questions and Answers for freshers focuses on “Tests on Stones”.
1. Which test is used to find the rate of wear of stones?
a) Crushing test
b) Abrasion test
c) Attrition test
d) Acid test
Explanation: Crushing test is used to find crushing strength of stones. Abrasion test to find suitability of stone for road work. Acid test is used to find the quality of the stone.
2. In what solution is the stone sample placed in an Acid test?
a) HCl of strength .5%
b) H2SO4 of strength .5%
c) H2SO4 of strength 1%
d) HCl of strength 1%
Explanation: As per the test procedure, the sample weighing about .5 – 1 N is placed in a solution of HCl for 7 days.
3. Which IS code gives details regarding the tests for weathering on building stones?
a) IS 1121 part 2
b) IS 1125
c) IS 1121 part 4
d) IS 1126
Explanation: IS 1121 part 2 gives details about transverse strength, IS 1121 part 4 about shear strength and IS 1126 about the durability of building stones.
4. For crushing test what is the size of a specimen to be used?
a) 50 × 50 × 50mm
b) 100 × 100 × 100mm
c) 45 × 45 × 45mm
d) 40 × 40 × 40mm
Explanation: As per the IS codes, 40 × 40 × 40 mm size cube of stone is to be used to perform the crushing test. The specimen is then placed in compression testing machine (CTM) and loaded at 14 N/mm2.
5. In abrasion test, what material is placed in addition to the specimen in the testing apparatus?
a) Metal piece
b) Stone piece smaller than specimen
c) Cast iron ball
d) Stainless steel ball
Explanation: Abrasion test is used to check compatibility of stone with other material by allowing them to rub against each other, noting the wear resistance. Cast iron balls of 48 mm diameter are placed in the apparatus along with the specimen.
6. Which apparatus is used to test the hardness of stones?
a) Los Angeles
Explanation: Los Angeles is used for abrasion test, Deval’s for attrition and CTM for compression or crushing test.
7. Which stone has a hardness of 7 in the Mohr’s hardness scale?
Explanation: Mohr’s hardness scale ranks stones according to their hardness numbers. Calcite has a hardness of 3, gypsum 2 and topaz 8.
8. Why CaSO4 is not used in the crystallisation test?
a) Costly compound
b) Low solubility in water
c) Increases time taken for test
d) Releases toxic fumes
Explanation: Crystallisation of CaSO4 in pores causes decay of stones and the low solubility in water prevent the use of this compound in the test.
9. Which of the below given formulas is used to calculate hardness coefficient?
a) (Final hardness / initial hardness) × 100%
b) 20 – (loss in weight / 2)
c) 20 – (loss in weight / 3)
d) ((20 – loss in weight) / 3) × 100%
Explanation: The coefficient of hardness is expressed as a number and not a percentage.
10. What are the specifications for tamping rod used in impact test?
a) 16 mm steel rod with rounded end
b) 16 mm steel rod with square face
c) 16 mm copper rod with rounded end
d) 16 mm copper rod with square face
Explanation: According to the IS code 2386, a 16 mm steel rod with rounded edge is used for tamping the sample filled inside the cylinder in three layers, 25 times each.
11. Why is attrition test performed?
a) To find resistance to scratch
b) To find resistance to weathering
c) To find resistance to wear
d) To find resistance to dressing
Explanation: Attrition test is performed to test the rate of wear of stones that are used in road construction. It checks the rubbing against the same material of stone and is expressed in percentage.
12. What parameter is being checked for in freezing and thawing test?
c) Water absorption
Explanation: Durability refers to the resistance of stones to atmospheric conditions such as rain, heat, snow; temperature gradients; chemical impurities; cracks, creeks.
Sanfoundry Global Education & Learning Series – Basic Civil Engineering.
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