Test 27 - Aggregate Strength, Toughness and Abrasion Tests

Question 1 ప్రశ్న 1

Which matching of aggregate mechanical property and test interpretation is most appropriate?

A Crushing value – resistance to gradually applied compressive load; impact value – resistance to sudden impact; Los Angeles abrasion value – resistance to wear and abrasion B Crushing value – resistance to chemical attack; impact value – specific gravity; Los Angeles abrasion value – water absorption C Crushing value – particle shape; impact value – grading; Los Angeles abrasion value – bulking D All three tests measure exactly the same property by identical loading

Question 2 ప్రశ్న 2

Which Indian Standard test-method part principally covers aggregate crushing value, ten percent fines value, aggregate impact value and aggregate abrasion value for concrete aggregates?

A IS 2386 (Part 1) B IS 2386 (Part 2) C IS 2386 (Part 3) D IS 2386 (Part 4)

Question 3 ప్రశ్న 3

For the standard aggregate crushing-value test, which size fraction is normally used?

A Passing 20 mm and retained on 4.75 mm sieve B Passing 12.5 mm and retained on 10 mm sieve C Passing 10 mm and retained on 2.36 mm sieve D Passing 4.75 mm and retained on 600 micrometre sieve

Question 4 ప్రశ్న 4

Which sequence best represents the standard aggregate crushing-value test under IS 2386 (Part 4)?

A Fill the cylinder in three layers with 25 strokes per layer, insert the plunger, apply the prescribed compressive load up to 40 tonnes at the specified uniform rate, then sieve the crushed material on the 2.36 mm sieve B Place aggregate in a Vicat mould, apply 15 hammer blows and sieve on the 90 micrometre sieve C Rotate aggregate with steel balls for 1000 revolutions and measure water absorption D Immerse aggregate in sulphate solution and determine crushing strength from mass loss

Question 5 ప్రశ్న 5

In an aggregate crushing-value test, the original surface-dry test sample weighs 2500 g and 620 g passes the specified 2.36 mm sieve after loading. What is the aggregate crushing value?

A 19.0 percent B 24.8 percent C 31.0 percent D 40.3 percent

Question 6 ప్రశ్న 6

Two aggregates tested by the same standard crushing-value procedure give ACV values of 19 percent and 27 percent. Which interpretation is generally correct?

A The aggregate with 27 percent is stronger because a larger ACV indicates greater crushing resistance. B The aggregate with 19 percent shows greater resistance to crushing under the test. C Both aggregates necessarily have identical mechanical strength. D ACV indicates only aggregate water absorption.

Question 7 ప్రశ్న 7

An aggregate proposed for concrete in a pavement wearing surface has an aggregate crushing value of 32 percent. What is the correct assessment under IS 383:2016?

A It complies because the maximum for wearing surfaces is 45 percent. B It does not comply with the 30 percent maximum for aggregates used in concrete wearing surfaces. C It automatically complies if its specific gravity exceeds 2.5. D Crushing value is not relevant to wearing-surface concrete.

Question 8 ప్రశ్న 8

For aggregate intended for concrete other than a wearing surface, IS 383:2016 states that if the aggregate crushing value exceeds 30 percent, which additional assessment should be made?

A The ten percent fines test should be conducted, with a minimum ten percent fines load of 50 kN. B The aggregate must automatically be rejected without any further mechanical test. C Only the flakiness index should be determined, with a minimum value of 50 percent. D The aggregate impact value must be exactly zero.

Question 9 ప్రశ్న 9

When comparing aggregates using the ten percent fines value, which general interpretation is correct?

A A higher load required to produce ten percent fines generally indicates a stronger aggregate. B A lower load required to produce ten percent fines always indicates a stronger aggregate. C The test measures only aggregate shape. D The result is expressed as water absorption percentage.

Question 10 ప్రశ్న 10

Which description correctly represents the standard aggregate impact-value test?

A A test sample is subjected to 15 blows from the specified hammer falling through approximately 380 mm, after which the fines passing the 2.36 mm sieve are measured. B Aggregate is subjected to a static 40-tonne load and the 1.70 mm fraction is measured. C Aggregate is rotated without an abrasive charge and the 75 micrometre fraction is determined. D Aggregate is immersed in water for 24 hours and the increase in mass is reported.

Question 11 ప్రశ్న 11

An oven-dry aggregate sample weighing 1400 g produces 350 g of fines passing the 2.36 mm sieve after the standard impact test. What is the aggregate impact value?

A 18 percent B 20 percent C 25 percent D 40 percent

Question 12 ప్రశ్న 12

Aggregate X has an impact value of 18 percent and Aggregate Y has an impact value of 35 percent. If both were tested identically, which conclusion is most appropriate?

A Aggregate X is generally tougher and more resistant to impact than Aggregate Y. B Aggregate Y is tougher because a larger percentage indicates better resistance. C Impact value compares only specific gravity. D The two aggregates necessarily have equal toughness.

Question 13 ప్రశ్న 13

Which pair correctly gives the IS 383:2016 maximum aggregate impact values for concrete wearing surfaces and concrete other than wearing surfaces respectively?

A 22 percent and 30 percent B 30 percent and 45 percent C 30 percent and 50 percent D 45 percent and 50 percent

Question 14 ప్రశ్న 14

For concrete of grade M65 and above, what special IS 383:2016 requirement applies to aggregate crushing value and aggregate impact value?

A Each shall not exceed 22 percent. B Each shall not exceed 30 percent only when the concrete is white. C Each shall not exceed 45 percent. D No mechanical-property limits apply.

Question 15 ప్రశ్న 15

A coarse aggregate proposed for a concrete pavement has ACV = 28 percent, AIV = 31 percent and Los Angeles abrasion value = 27 percent. Which conclusion is correct under the stated wearing-surface limits?

A It satisfies all three mechanical requirements. B It fails only the aggregate impact-value requirement. C It fails only the crushing-value requirement. D It fails only the abrasion-value requirement.

Question 16 ప్రశ్న 16

What is the principal engineering interpretation of the Los Angeles abrasion test?

A It evaluates resistance of coarse aggregate to degradation by abrasion and impact in a rotating drum with an abrasive steel charge. B It measures only the water absorption of coarse aggregate. C It determines the initial setting time of aggregate. D It measures fine-aggregate bulking under moisture.

Question 17 ప్రశ్న 17

In the Los Angeles abrasion test under IS 2386 (Part 4), which sieve is used in determining the final material retained for calculation of percentage wear?

A 90 micrometre sieve B 600 micrometre sieve C 1.70 mm sieve D 4.75 mm sieve only

Question 18 ప్రశ్న 18

A Los Angeles abrasion test begins with 5000 g of aggregate. After the prescribed test, sieving, washing and drying, 3650 g is retained as the final coarse material. What is the Los Angeles abrasion value or percentage wear?

A 17 percent B 27 percent C 36.5 percent D 73 percent

Question 19 ప్రశ్న 19

Which pair correctly gives the maximum Los Angeles abrasion values under IS 383:2016 for aggregate used in concrete wearing surfaces and concrete other than wearing surfaces respectively?

A 22 percent and 30 percent B 30 percent and 45 percent C 30 percent and 50 percent D 45 percent and 50 percent

Question 20 ప్రశ్న 20

Aggregate A has a Los Angeles abrasion value of 18 percent and Aggregate B has a value of 35 percent. For otherwise comparable aggregate proposed for a concrete wearing surface, which statement is correct?

A Both fail the 30 percent maximum. B Aggregate A satisfies the abrasion requirement, while Aggregate B does not. C Aggregate B is more abrasion resistant because its value is higher. D Both automatically comply because Los Angeles abrasion is not specified for concrete aggregate.

Question 21 ప్రశ్న 21

For the Los Angeles abrasion test, which statement about the prescribed number of revolutions is correct?

A Gradings A, B, C and D use 500 revolutions, while gradings E, F and G use 1000 revolutions. B Every grading uses exactly 15 revolutions. C Gradings A to D use 1000 revolutions and E to G use 500 revolutions. D The number of revolutions is unrelated to test-sample grading.

Question 22 ప్రశ్న 22

Which of the following apparatus-test pairs is INCORRECT?

A Compression testing machine with crushing cylinder and plunger – aggregate crushing value B Impact testing machine with falling hammer – aggregate impact value C Los Angeles rotating drum with steel abrasive charge – aggregate abrasion value D Vicat apparatus with standard plunger – aggregate impact value

Question 23 ప్రశ్న 23

A coarse aggregate is proposed for the concrete lining of a tunnel carrying high-velocity water. Why should the stricter wearing-surface mechanical limits be considered?

A IS 383 explicitly treats tunnel lining carrying water among applications where concrete aggregate is subject to wearing action. B Tunnel concrete is classified as masonry mortar rather than concrete. C Only aggregate colour matters in water-carrying tunnels. D Water exposure eliminates the need for abrasion-resistant aggregate.

Question 24 ప్రశ్న 24

Which statement best explains why aggregate crushing value, impact value and Los Angeles abrasion value should not be used interchangeably?

A They impose different forms of mechanical action and therefore assess different aspects of aggregate resistance. B All three tests use the same apparatus and loading history. C Each test measures only aggregate chemical composition. D A passing result in one test automatically proves the numerical result of the other two.

Question 25 ప్రశ్న 25

Two aggregate sources are being considered for a concrete floor subjected to heavy wheeled traffic. Source X satisfies compressive concrete-strength trials but has a Los Angeles abrasion value above the applicable wearing-surface limit. Which decision is most appropriate?

A Accept Source X because concrete compressive strength automatically overrides aggregate abrasion requirements. B Do not accept Source X solely on strength performance when it fails an applicable mandatory abrasion-resistance requirement. C Ignore abrasion because only aggregate impact value can affect a wearing surface. D Increase the water-cement ratio until the aggregate abrasion value decreases.

Question 26 ప్రశ్న 26

Consider the following statements about aggregate mechanical tests:
1. Lower aggregate crushing value generally indicates greater resistance to crushing.
2. Lower aggregate impact value generally indicates greater toughness.
3. Lower Los Angeles abrasion value generally indicates greater resistance to wear.
4. For the ten percent fines test, a higher load required to produce ten percent fines generally indicates a stronger aggregate.

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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