Test 14 - Cement Fundamentals and Engineering Properties

Question 1 ప్రశ్న 1

Why is Portland cement classified as a hydraulic cement?

A Because it hardens only when exposed to dry air B Because it reacts with water, sets and hardens, and the hardened binder can remain stable under water C Because hydraulic pressure is required to manufacture it D Because it contains only water-soluble compounds

Question 2 ప్రశ్న 2

What is meant by hydration of cement in Civil Engineering?

A The chemical reactions between cement constituents and water that form new hydrated products B The physical evaporation of all water immediately after mixing C The grinding of cement clinker in the absence of water D The absorption of atmospheric carbon dioxide by dry cement powder only

Question 3 ప్రశ్న 3

Which statement correctly distinguishes setting from hardening of cement?

A Setting and hardening are exactly the same instantaneous event. B Setting refers only to evaporation of water, while hardening refers only to drying. C Setting is the progressive loss of plasticity and development of rigidity, whereas hardening is the subsequent development of strength. D Hardening must finish before initial setting begins.

Question 4 ప్రశ్న 4

Which hydration product is principally responsible for the binding action and a major part of the strength of hydrated Portland cement paste?

A Calcium silicate hydrate, commonly abbreviated as C-S-H B Unreacted gypsum alone C Free calcium oxide alone D Calcium carbonate present as quarry dust

Question 5 ప్రశ్న 5

Compared with dicalcium silicate (C2S), tricalcium silicate (C3S) in Portland cement generally:

A Hydrates more slowly and contributes mainly to very late strength B Hydrates more rapidly and contributes substantially to early strength development C Has no role in cement strength D Prevents all heat evolution during hydration

Question 6 ప్రశ్న 6

Which statement best describes the engineering role of dicalcium silicate (C2S) in Portland cement?

A It reacts relatively slowly and contributes significantly to later-age strength with comparatively lower heat evolution. B It is solely responsible for flash setting. C It prevents cement from hardening. D It is added after hydration solely to increase colour.

Question 7 ప్రశ్న 7

Why is the rapid reaction of tricalcium aluminate (C3A) important in understanding the setting behaviour of Portland cement?

A C3A is completely inert in the presence of water. B C3A reacts rapidly and can cause excessively rapid stiffening unless its reaction is suitably controlled. C C3A is the only compound responsible for 28-day compressive strength. D C3A prevents all other clinker phases from hydrating.

Question 8 ప్రశ్న 8

What is the principal purpose of adding a controlled quantity of gypsum during the manufacture of Ordinary Portland Cement?

A To regulate the rapid hydration of aluminate phases and control the setting of cement B To convert hardened cement back into clinker C To eliminate the need for water during concrete production D To make cement chemically inert

Question 9 ప్రశ్న 9

A very large mass-concrete element is being designed, and excessive temperature rise from cement hydration is a major cracking concern. Which cement behaviour is most desirable?

A Very high heat liberation concentrated in the first few hours B Instantaneous setting immediately after water addition C A comparatively low and gradual rate of heat evolution compatible with the required strength development D Complete absence of hydration

Question 10 ప్రశ్న 10

If two otherwise similar Portland cements differ mainly in fineness, what is generally expected from the finer cement?

A A larger specific surface available for hydration and generally faster early reaction B Complete prevention of hydration C Zero early strength development D Automatic elimination of the need for curing

Question 11 ప్రశ్న 11

Why is it incorrect to assume that cement should simply be ground as fine as possible without considering any other property?

A Greater fineness can accelerate hydration and early strength development but may also increase water demand, early heat evolution and manufacturing energy requirements. B Fineness has absolutely no effect on cement behaviour. C Coarser cement always hydrates completely before finer cement. D Very fine cement cannot chemically react with water.

Question 12 ప్రశ్న 12

What does the standard consistency of cement paste represent?

A The maximum strength of concrete containing the cement B The percentage of water required to produce a cement paste having the specified standard penetration in the Vicat apparatus C The percentage of aggregate required in a concrete mix D The percentage of cement retained on every sieve

Question 13 ప్రశ్న 13

A 400 g cement sample requires 116 g of water to obtain standard consistency. What is the standard consistency of the cement?

A 24 percent B 26 percent C 29 percent D 34 percent

Question 14 ప్రశ్న 14

What engineering property of cement is primarily assessed by a soundness test?

A Resistance to undesirable delayed volumetric expansion after setting B Colour uniformity of the dry powder C Maximum aggregate size suitable for concrete D Tensile strength of reinforcing steel

Question 15 ప్రశ్న 15

Which constituents are particularly associated with potentially harmful delayed expansion when present in unsuitable forms or excessive amounts in Portland cement?

A Stable quartz aggregate and mixing water B Free lime and magnesia C C-S-H and entrapped air alone D Standard graded sand and gypsum moulds

Question 16 ప్రశ్న 16

Match the cement property with the corresponding IS 4031 physical-test part:
1. Fineness by Blaine air permeability
2. Soundness
3. Standard consistency
4. Initial and final setting times
5. Compressive strength

P. Part 3
Q. Part 6
R. Part 2
S. Part 5
T. Part 4

A 1-R, 2-P, 3-T, 4-S, 5-Q B 1-P, 2-R, 3-S, 4-T, 5-Q C 1-R, 2-Q, 3-P, 4-S, 5-T D 1-T, 2-S, 3-R, 4-P, 5-Q

Question 17 ప్రశ్న 17

Under IS 269:2015, what does the designation 'OPC 43 Grade' principally signify?

A The cement must contain exactly 43 percent C3S. B The concrete made with it must always have a characteristic strength of exactly 43 MPa. C The cement must reach an initial setting time of exactly 43 minutes. D The standard mortar compressive strength at 28 days must satisfy the specified minimum of 43 MPa.

Question 18 ప్రశ్న 18

Which set correctly gives the minimum compressive strengths specified in IS 269:2015 for ordinary OPC 53 Grade at approximately 3, 7 and 28 days respectively?

A 16, 22 and 33 MPa B 23, 33 and 43 MPa C 27, 37 and 53 MPa D 33, 43 and 53 MPa

Question 19 ప్రశ్న 19

For ordinary OPC 33, OPC 43 and OPC 53 under IS 269:2015, which pair correctly states the basic setting-time requirements?

A Initial setting time not less than 30 minutes and final setting time not more than 600 minutes B Initial setting time exactly 10 minutes and final setting time exactly 30 minutes C Initial setting time not more than 30 minutes and final setting time not less than 600 minutes D Both initial and final setting times must be exactly 600 minutes

Question 20 ప్రశ్న 20

A sample of OPC 43 has an initial setting time of 25 minutes and satisfies all other stated physical requirements. What is the correct assessment under IS 269:2015?

A It complies because any value below 30 minutes is preferable. B It does not comply with the initial-setting-time requirement. C It automatically becomes OPC 53 Grade. D Initial setting time is not a specified property of OPC.

Question 21 ప్రశ్న 21

An OPC 53 sample has a final setting time of 620 minutes. Assuming the applicable IS 269:2015 requirement is a maximum of 600 minutes, what is the correct conclusion?

A It complies because a longer final setting time is always acceptable. B It fails the stated final-setting-time requirement. C It should automatically be reclassified as OPC 43. D Final setting time is determined by a compression test and therefore cannot be compared.

Question 22 ప్రశ్న 22

The Blaine specific surface of an ordinary OPC 43 sample is 220 m²/kg. If IS 269:2015 requires a minimum of 225 m²/kg for this grade, what is the correct conclusion?

A The cement satisfies the fineness requirement because lower specific surface means greater fineness. B The cement fails the stated fineness requirement. C The cement automatically becomes rapid-hardening Portland cement. D Blaine specific surface has no relationship with cement fineness.

Question 23 ప్రశ్న 23

An ordinary OPC 33 sample shows a Le Chatelier expansion of 11 mm. If the IS 269:2015 maximum for unaerated OPC 33 is 10 mm, what does this result indicate?

A It satisfies the soundness requirement because expansion should exceed 10 mm. B It proves that the cement has 53 MPa compressive strength. C It does not satisfy the stated Le Chatelier soundness limit in that test condition. D It establishes that the cement has zero free lime.

Question 24 ప్రశ్న 24

Which statement correctly distinguishes flash set from false set in cement?

A Flash set is rapid irreversible stiffening associated with intense early reaction and heat, whereas false set is premature stiffening that can generally be overcome by continued remixing without adding water. B False set permanently prevents remixing, while flash set is corrected simply by ordinary remixing. C Both terms mean normal final setting after 28 days. D Both phenomena are measures of cement fineness only.

Question 25 ప్రశ్న 25

Consider the following statements about cement engineering behaviour:
1. Hydration is exothermic.
2. Final setting does not mean that all strength development has ended.
3. C3S generally contributes more to early strength than C2S.
4. A cement satisfying a higher OPC grade automatically produces concrete of the same numerical grade regardless of mix proportions and curing.

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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