Test 37 - Testing of Hardened Concrete

Question 1 ప్రశ్న 1

Which current Indian Standard directly provides the procedures for compressive, flexural and split tensile strength testing of hardened concrete?

A IS 516 (Part 1/Sec 1):2021 B IS 1199 (Part 2):2018 C IS 2386 (Part 4):1963 D IS 4031 (Part 6):1988

Question 2 ప్రశ్న 2

Which standard principally specifies the shape, dimensions, making and curing of concrete specimens used for strength tests?

A IS 1199 (Part 5):2018 B IS 383:2016 C IS 9103:1999 D IS 2386 (Part 1):1963

Question 3 ప్రశ్న 3

What is the standard cube specimen size for concrete strength testing, and when may the smaller alternative cube be used?

A 150 mm cube; a 100 mm cube may be used when the largest nominal aggregate size does not exceed 20 mm B 100 mm cube only, irrespective of aggregate size C 200 mm cube; a 150 mm cube may be used only for lightweight concrete D 300 mm cube; a 200 mm cube may be used when aggregate exceeds 40 mm

Question 4 ప్రశ్న 4

What is the standard cylindrical concrete specimen size specified in IS 1199 (Part 5) for strength testing?

A 100 mm diameter × 100 mm length B 100 mm diameter × 200 mm length C 150 mm diameter × 300 mm length D 200 mm diameter × 300 mm length

Question 5 ప్రశ్న 5

Which set correctly gives the standard and alternative beam specimen sizes for flexural-strength testing?

A Standard 150 × 150 × 700 mm; alternative 100 × 100 × 500 mm when the largest nominal aggregate size does not exceed 20 mm B Standard 100 × 100 × 300 mm; alternative 50 × 50 × 150 mm C Standard 150 × 300 × 300 mm; alternative 100 × 200 × 200 mm D Standard 200 × 200 × 1000 mm only, with no alternative

Question 6 ప్రశ్న 6

Which statement about test age and number of specimens is correct under IS 516 (Part 1/Sec 1):2021?

A The usual test ages include 7 and 28 days, and at least three specimens are tested at each selected age. B Only one specimen is tested and only at 28 days. C Exactly two specimens must be tested at every age. D Concrete strength cannot be tested before 28 days.

Question 7 ప్రశ్న 7

Which statement correctly describes the compression testing machine used under IS 516 (Part 1/Sec 1):2021?

A It should conform to IS 14858, be in calibration at the time of testing and be calibrated at least once per year. B Any uncalibrated hydraulic jack may be used. C Calibration is required only once when the machine is purchased. D The machine is required only for flexural testing and not compression testing.

Question 8 ప్రశ్న 8

A concrete cube has been stored in water before its compressive-strength test. Which procedure is appropriate immediately before testing?

A Wipe off excess surface moisture and test as soon as possible, normally within 2 hours of removal while protecting it from drying. B Dry the cube in an oven for 24 hours. C Leave the cube exposed in sunlight until its mass becomes constant. D Immerse the cube in oil before placing it in the testing machine.

Question 9 ప్రశ్న 9

How should a cast concrete cube normally be oriented during the compressive-strength test?

A The compressive load should act perpendicular to the direction of casting. B The load must always act directly on the trowelled surface. C The cube should be placed randomly because orientation has no test significance. D The load must be applied only through two opposite corners.

Question 10 ప్రశ్న 10

What is the specified compressive loading rate under IS 516 (Part 1/Sec 1):2021?

A 0.7 N/mm²/min B 1.2 to 2.4 N/mm²/min C 14 N/mm²/min D 140 N/mm²/min

Question 11 ప్రశ్న 11

A 150 mm concrete cube fails under a maximum compressive load of 675 kN. What is its compressive strength?

A 20 N/mm² B 25 N/mm² C 30 N/mm² D 45 N/mm²

Question 12 ప్రశ్న 12

What maximum load corresponds to a compressive stress of 40 N/mm² on a 150 mm cube?

A 450 kN B 675 kN C 900 kN D 1200 kN

Question 13 ప్రశ్న 13

How is compressive strength reported under IS 516 (Part 1/Sec 1):2021?

A To the nearest 0.01 MPa B To the nearest 0.05 MPa C To the nearest 0.5 MPa D Only to the nearest 10 MPa

Question 14 ప్రశ్న 14

Three compressive-strength specimens are tested as a set. Which statement correctly describes the IS 516 rule for using their average as representative of the batch?

A The average of the three is representative provided the individual variation is not more than ±15 percent of the average. B Every value must be exactly equal to the average. C The highest result alone is always adopted. D The lowest result is discarded automatically regardless of its deviation.

Question 15 ప్రశ్న 15

Three concrete cubes give compressive strengths of 30, 32 and 34 MPa. Based only on the IS 516 ±15 percent variation requirement, which conclusion is correct?

A The results satisfy the variation requirement and the average is 32 MPa. B The results fail because all three strengths must be identical. C Only the 34 MPa result should be reported. D The average is 34 MPa.

Question 16 ప్రశ్న 16

How should a badly honeycombed standard cube or cylinder generally be treated in a strength-testing programme?

A It should not normally be regarded as representative of the concrete quality, and poor specimen condition should be identified in the test record if it is tested. B Its result must automatically be increased by 15 percent. C Honeycombing has no relevance to a strength specimen. D It must always be accepted as the most representative specimen.

Question 17 ప్రశ్న 17

Which description correctly represents the loading arrangement for the standard 150 × 150 × 700 mm flexural-strength specimen?

A A 600 mm support span with two upper loading rollers at the third points, spaced 200 mm apart B A 300 mm support span with one central point load only C A 700 mm support span with no loading rollers D A 150 mm support span with direct axial compression

Question 18 ప్రశ్న 18

What is the specified stress-loading rate for the flexural-strength test under IS 516 (Part 1/Sec 1):2021?

A 0.7 N/mm²/min, corresponding to about 4 kN/min for the 150 mm specimen B 14 N/mm²/min, corresponding to about 315 kN/min C 1.2 to 2.4 N/mm²/min for every beam size D 100 N/mm²/min

Question 19 ప్రశ్న 19

A 150 mm × 150 mm flexural specimen is tested on a 600 mm span and fails at a maximum total load of 18 kN with the fracture occurring within the Type A region. Using Fb = PL/(BD²), what is the flexural strength?

A 2.40 MPa B 3.20 MPa C 4.00 MPa D 4.80 MPa

Question 20 ప్రశ్న 20

A 150 mm flexural specimen fails at P = 18 kN with the fracture located a = 180 mm from the nearer support. Using Fb = 3Pa/(BD²), what value should be reported to the nearest 0.05 MPa?

A 2.80 MPa B 2.85 MPa C 2.90 MPa D 3.20 MPa

Question 21 ప్రశ్న 21

For a 150 mm flexural specimen, what should be done if the distance a between the fracture line and the nearer support is less than 170 mm?

A The result should be discarded. B The value PL/(BD²) should always be used. C The measured strength should automatically be doubled. D The result should be converted into split tensile strength.

Question 22 ప్రశ్న 22

What is the basic principle of the splitting tensile-strength test?

A A compressive line load is applied diametrically so that transverse tensile stress develops and splits the specimen. B The specimen is pulled directly from its ends until it separates. C The specimen is subjected only to hydrostatic pressure. D The concrete is crushed uniformly on all six faces.

Question 23 ప్రశ్న 23

Which statement about specimens and load application in the current split tensile-strength test is correct?

A Both cube and cylinder specimens are permitted, and suitable packing/loading strips are used to apply the line load. B Only beam specimens can be used. C Only hollow cylinders can be tested. D The compressive load is applied uniformly over the complete end face exactly as in a conventional compression test.

Question 24 ప్రశ్న 24

A 150 mm diameter, 300 mm long concrete cylinder fails in split tension under P = 200 kN. Using fct = 2P/(πLD), what split tensile strength should be reported to the nearest 0.05 MPa?

A 2.80 MPa B 2.83 MPa C 2.85 MPa D 3.00 MPa

Question 25 ప్రశ్న 25

What loading-rate range is specified for the split tensile-strength test?

A 0.1 to 0.2 N/mm²/min B 0.7 N/mm²/min exactly C 1.2 to 2.4 N/mm²/min D 14 to 28 N/mm²/min

Question 26 ప్రశ్న 26

Consider the following statements about hardened-concrete strength testing:
1. The current IS 516 (Part 1/Sec 1):2021 covers compressive, flexural and split tensile strength.
2. Standard cube compressive loading is applied at 14 N/mm²/min.
3. Flexural test results may have to be discarded when fracture occurs outside the permitted location.
4. The split tensile test directly pulls a concrete cylinder axially from its ends.

Which statements are correct?

A 1 and 2 only B 1, 2 and 3 only C 2, 3 and 4 only D 1, 2, 3 and 4

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