Quiznetik

Concrete Technology | Set 2

1. What are plasticizers?

Correct : B. Which reduces water for workability

2. What is the amount used of plasticizers in cement by weight?

Correct : B. 1-.4%

3. What is the allowed reduction of water with super plasticizers without reducing workability?

Correct : C. 30%

4. What is accelerator?

Correct : A. Which speed up the initial set of concrete

5. What is retender?

Correct : B. Which delays the initial set of concrete

6. NaOH is the example of retenders.

Correct : B. False

7. Pick up the correct statement from the following.

Correct : C. Gypsum acts as a retarders

8. Retarders used at grouting oil wells, where temperature is about _____________ oC.

Correct : C. 200

9. Silica fume is ______________

Correct : C. More reactive

10. What is the content of SiO2 in fly ash?

Correct : A. 30-60%

11. Air entrainment in concrete increases ___________

Correct : B. Workability

12. What is curing?

Correct : B. Hydration

13. What is the gel/space ratio?

Correct : C. Volume of the hydrated cement paste to the sum of volumes of the hydrated cement and of the capillary pores

14. Gel/Space ratio = x = Volume of gel / Space available = 0.657 C / 0.319 C+ Wo. Here Wo stands for?

Correct : D. Volume of mixing water in ml

15. This strain increases over time due to _________

Correct : A. Creep

16. If the stress is removed, the specimen shows an instantaneous recovery strain ___ the elastic strain on loading.

Correct : B. Lower than

17. Creep ___ as the age of application of load _____

Correct : D. Decrease, increase

18. Shrinkage is the reduction in the volume of a fresh hardened concrete exposed to ambient temp and humidity.

Correct : A. True

19. Durability of concrete is proportional to _________

Correct : D. Cement aggregate ratio

20. For concrete exposed to a very aggressive environment the w/c should be lower than __________

Correct : C. 4

21. The quality of concrete, specifically a ____________ w/c ratio, is the best protection against sulphate attack.

Correct : C. Low

22. The continuous strain, which the concrete undergoes due to application of external loads, is called __________

Correct : D. Creep

23. Harshness in concrete is due to the excess of _____________

Correct : C. Middle sized particle

24. __________ has designated the concrete mixes into a number of grades as M10, M15.

Correct : A. IS 456-2000

25. What is the approx. mix proportion for M10?

Correct : A. 1:3:6

26. Quality control helps to ___________ the risks of overdesign that ___________ the overall cost.

Correct : D. Minimize, Decrease

27. The cement concrete, from which entrained air and excess water are removed after placing it in position, is called ________

Correct : A. Vacuum concrete

28. The light-weight concrete is prepared by ____________

Correct : B. Using coke-breeze, slag as aggregate in the concrete

29. Aerated Concrete is ______________

Correct : D. Light weight

30. No fines concrete is manufactured by _____________

Correct : B. By eliminating no fines materials from normal concrete

31. Density of no fines concrete with light weight aggregate vary from ________ kg/m3.

Correct : B. <300

32. Diameter of Round Steel Fiber lies in the range of ________ mm.

Correct : B. .25-.75

33. Air contents should be _________ % by volume.

Correct : C. 3-4

34. Which one is not used as air entraining agents?

Correct : A. Alumina

35. What is wet process?

Correct : C. Grinding and mixing of the raw materials in their wet state

36. Excess in lime causes _______

Correct : D. The cement to expand and disintegrate

37. Silica in excess causes ________

Correct : A. The cement to set slowly

38. Alumina in excess causes _________

Correct : A. Reduces the strength of the cement

39. Which compound gives the colour to the cement?

Correct : C. Iron Oxide

40. Which cement contains high percentage of C3S and less percentage of C2S?

Correct : A. Rapid Hardening Cement

41. When concrete is to be laid under water ___________ is to used.

Correct : C. Quick Setting Cement

42. Which of the following is correct for Low Heat Cement?

Correct : B. Heat of hydration is reduced by tri calcium aluminate content

43. Which cement is used in sewage and water treatment plants?

Correct : C. Sulphate Resisting Cement

44. Which cement is used for mainly building construction where strength required with age?

Correct : C. Portland Pozzolana Cement

45. Which cement is used for artificial marble?

Correct : C. Coloured Cement

46. Which cement is used to create bond with old concrete surface?

Correct : B. Expansive Cement

47. Which cement is used to store for longer duration in wet climatic conditions?

Correct : C. Hydrophobic Cement

48. Which cement is used for the construction of water-retaining structure like tanks, reservoirs, retaining walls, swimming pools, dams, bridges, piers etc?

Correct : A. Waterproof Portland cement

49. ____ Cement is used for formwork that can be removed earlier and reused in other areas which save the cost of formwork.

Correct : A. Rapid Hardening Cement

50. Which cement is mainly used for interior and exterior decorative works?

Correct : B. Colored Cement

51. Which cement is used for works economic where considerations is predominant? Reservoirs, retaining walls, swimming pools, dams, bridges, piers etc.

Correct : D. Blast Furnace Slag Cement

52. How many times in each layer of concrete rodded in a slump cone?

Correct : B. 25

53. If L1=Measurement taken after 24 hours of immersion in water at a temp. of 27 ± 20oC and L2=Measurement taken after 3 hours of immersion in water at boiling temperature. Then what is soundness of cement?

Correct : C. L1-L2

54. Which of the following option is correct?

Correct : A. Standard consistency (%) = (wt of water added/ wt of cement) *100

55. According to geological origin, aggregates is/are classified into __________ types.

Correct : B. 2

56. Crushed stone, gravel and ordinary sand are examples of ___________

Correct : B. Normal-weight aggregate

57. Which type of aggregate is shown below?

Correct : C. Flaky aggregate

58. The rock which is not calcareous, is :

Correct : D. Laterite

59. The main object of compaction of concrete, is:

Correct : D. all the above.

60. Grading of aggregates should be continuous for

Correct : A. lean

61. The aggregates of

Correct : B. angular

62. Which of the following ingredient of cement when added in excess quantity, causes the cement to set slowly?

Correct : B. silica

63. An aggregate having all the pores filled with water but having dry surface is called

Correct : C. saturated surface dry aggregate

64. The internal friction between the ingredients of concrete is minimised by

Correct : D. all of these

65. The light-weight concrete is prepared by

Correct : B. using coke-breeze, cinder or slag as aggregate in the concrete

66. For compacting plain concrete or one-way reinforced concrete floors, the vibrator used is

Correct : B. screed vibrator

67. The surface moisture of aggregates increases the water-cement ratio in the mix and thus

Correct : B. decreases

68. For compacting large sections of mass concrete in structures, the type of vibrator used is

Correct : A. internal vibrator

69. The presence of

Correct : A. sodium carbonate and bicarbonate

70. The tetra calcium alumino ferrite in cement has

Correct : B. poor

71. For reinforced concrete, the aggregate used is

Correct : D. all of these

72. The lime concrete has

Correct : A. less

73. The steel mould used for slump test is in the form of a

Correct : C. frustrum of a cone

74. In order to avoid segregation, the concrete should not be thrown from a height.

Correct : A. Agree

75. Water cement ratio may be defined as the ratio of

Correct : B. weight of water to that of cement in a concrete mix

76. Low heat cement contains more lime than ordinary Portland cement.

Correct : B. False

77. For concreting of tunnel lining, the concrete is transported by

Correct : A. pumps

78. For the improvement of workability of concrete, the shape of aggregate recommended is

Correct : C. round

79. Which of the following statement is correct?

Correct : D. all of the above

80. For a structure subjected to the action of sea water, the cement used is

Correct : C. high alumina cement

81. For high degree of workability, the slump value should vary between

Correct : D. 80 to 100 mm

82. The term 'ware-hourse pack' means

Correct : C. pressure compaction of bags on lower layers

83. The length of Vicat plunger in Vicat's apparatus varies from

Correct : C. 40 to 50 mm

84. The cement concrete prepared by mixing aluminium in it, is called

Correct : D. any one of the above

85. Plain cement concrete is strong in taking

Correct : B. compressive stress

86. As per IS : 459-1978, the concrete mixes are designated into

Correct : D. 7 grades

87. The factor which effect the quality of compaction, is

Correct : D. all of these

88. The top diameter, bottom diameter and height of the mould used for slump test are respectively

Correct : A. 100 mm, 200 mm, 300 mm

89. The aggregate which pass through 75 mm IS sieve and entirely retain on 4.75 mm IS sieve is known as

Correct : B. coarse aggregate

90. The rate of hydration is

Correct : A. directly

91. Weight batching is done by

Correct : D. all of these

92. The first compound which reacts with water when mixed with cement is tricalcium aluminate.

Correct : A. Correct

93. An aggregate which may contain some moisture in the pores but having dry surface is known as

Correct : B. dry aggregate

94. Proper curing of cement concrete, is good for its

Correct : D. all of these

95. Hydration of cement is due to the chemical action of water with

Correct : D. all of these

96. The cement concrete in which high compressive stresses are artificially induced before its actual use, is called

Correct : C. prestressed cement concrete

97. The fineness modulus of an aggregate is roughly proportional to

Correct : C. average size of particles in the aggregate

98. The water used for ordinary concrete is equal to 5% by weight of aggregate plus

Correct : C. 30%

99. Which of the following statement is wrong?

Correct : D. all of the above

100. The sound absorption coefficient of light weight concrete is nearly

Correct : A. twice