concrete technology Flashcards
Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete. If the compaction factor is 0.95, the workability of concrete is
[A]. extremely low [B]. very low [C]. low [D]. high @ [E]. none of these.
Extremely low - 0.65 to 0.68.
Very low - 0.75.
low - 0.83 to 0.85.
Medium - 0.90 to 0.92.
High - 0.95.
According to I.S. : 456, the number of grades of concrete mixes, is
[A]. 3 [B]. 4 [C]. 5 [D]. 6 [E]. 7 @
According to old code(IS 456-1978) there are 7 grades of concrete(M10 to M40).
According to new code(IS 456-2000) there are 9 grades (M10 to M50).
While compacting the concrete by a mechanical vibrator, the slump should not exceed
[A]. 2.5 cm [B]. 5.0 cm @ [C]. 7.5 cm [D]. 10 cm [E]. 15 cm
While compacting the concrete by a mechanical vibrator, the slump should not exceed
[A]. 2.5 cm [B]. 5.0 cm @ [C]. 7.5 cm [D]. 10 cm [E]. 15 cm
Construction joints are provided
[A]. where B.M. and S.F. are small
[B]. where the member is supported by other member
[C]. at 18 m apart in huge structures
[D]. in concrete wall at sill level of windows
[E]. all the above. @
Construction joints are provided
[A]. where B.M. and S.F. are small
[B]. where the member is supported by other member
[C]. at 18 m apart in huge structures
[D]. in concrete wall at sill level of windows
[E]. all the above. @
The ratio of the length to breadth of a wooden float, is
[A]. 4.5 [B]. 5.5 [C]. 6.5 [D]. 7.5 @ [E]. 8.5
The ratio of the length to breadth of a wooden float, is
[A]. 4.5 [B]. 5.5 [C]. 6.5 [D]. 7.5 @ [E]. 8.5
To ensure constant moisture content in aggregates
[A]. area of each aggregate pile should be large
[B]. height of each aggregate pile should not exceed 1.50 m
[C]. aggregate pile should be left for 24 hours before aggregates are used
[D]. conical heaps of aggregates should be avoided to prevent moisture variation
[E]. all the above. @
To ensure constant moisture content in aggregates
[A]. area of each aggregate pile should be large
[B]. height of each aggregate pile should not exceed 1.50 m
[C]. aggregate pile should be left for 24 hours before aggregates are used
[D]. conical heaps of aggregates should be avoided to prevent moisture variation
[E]. all the above. @
If 20 kg of coarse aggregate is sieved through 80 mm, 40 mm, 20 mm, 10 mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron and 150 micron standard sieves and the weights retained are 0 kg, 2 kg, 8 kg, 6 kg, 4 kg respectively, the fineness modulus of the aggregate, is
[A]. 7.30 [B]. 7.35 [C]. 7.40 @ [D]. 7.45 [E]. none of these.
% RETAINED CUMULATIVE % RETAINED
80 MM 0 0 0 40 2 10 10 20 8 40 50 10 6 30 80 4.75 4 20 100 2.36 0 0 100 1.18 0 0 100 600 0 0 100 300 0 0 100 150 0 0 100
TOTAL 740.
FINENESS MODULUS = 740/100 = 7.4.
For the construction of cement concrete floor, the maximum permissible size of aggregate, is
[A]. 4 mm [B]. 6 mm [C]. 8 mm [D]. 10 mm @ [E]. 12 mm
40 mm for massive works like dams, retaining walls, etc.
20 mm for Reinforced member.
10 mm for floors.
The preliminary test is repeated if the difference of compressive strength of three test specimens, exceeds
[A]. 5 kg/cm2 [B]. 8 kg/cm2 [C]. 10 kg/cm2 [D]. 12 kg/cm2 [E]. 15 kg/cm2 @
As per IS 516 Average of three values shall be taken as the representative of the batch provided the Individual variation is not more than ± 15 percent of the average.
Otherwise repeat tests shall be made.
Transport of concrete by pumps, is done for a distance of
[A]. 100 m [B]. 200 m [C]. 300 m [D]. 400 m @ [E]. none of these.
Transport of concrete by pumps, is done for a distance of
[A]. 100 m [B]. 200 m [C]. 300 m [D]. 400 m @ [E]. none of these.
The rock which is not calcareous, is :
[A]. lime stone [B]. macl [C]. chalk [D]. laterite @ [E]. none of these.
The mineralogical and chemical compositions of laterites are dependent on their parent rocks. Laterites consist mainly of quartz, zircon, and oxides of titanium, iron, tin, aluminium and manganese, which remain during the course of weathering.
1.S. Sieve Nos. 10 mm and 4.75 mm are geneally used for grading of
[A]. coarse aggregates [B]. fine aggregates [C]. neither (a) nor (b) [D]. both (a) and (b) @ [E]. none of these.
80, 40, 20, 10, 4.75 —–» Coarse aggregates.
4.75, 2.36, 1.18, 600 micron, 300 micron, 150 micron —-» Fine Aggregates.
Pick up the correct statement from the following:
[A]. The free water is the amount of water added while mixing and the amount of water held on the surface of the aggregates prior to mixing
[B]. The total water is the free water and the amount actually absorbed by the aggregates
[C]. Neither (a) nor (b)
[D]. Both (a) and (b). @
Pick up the correct statement from the following:
[A]. The free water is the amount of water added while mixing and the amount of water held on the surface of the aggregates prior to mixing
[B]. The total water is the free water and the amount actually absorbed by the aggregates
[C]. Neither (a) nor (b)
[D]. Both (a) and (b). @
Pick up the correct statement from the following:
[A]. Lime in excess, causes the cement to expand and disintegrate
[B]. Silica in excess, causes the cement to set slowly
[C]. Alumina in excess, reduces the strength of the cement
[D]. Magnesium oxide in excess, remains in free state and makes the cement unsound
[E]. All the above. @
Pick up the correct statement from the following:
[A]. Lime in excess, causes the cement to expand and disintegrate
[B]. Silica in excess, causes the cement to set slowly
[C]. Alumina in excess, reduces the strength of the cement
[D]. Magnesium oxide in excess, remains in free state and makes the cement unsound
[E]. All the above. @
For construction of structures in sea water, the cement generally preferred to, is
[A]. Portland-pozzolana cement @ [B]. quick setting cement [C]. low heat Portland cement [D]. rapid hardening cement [E]. none of these.
For marine or structure constructed in the sea the following cement are used. They are
A) portland pozzolana cement
B) high alumina cement
C) sulphate resisting cement
Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is
[A]. 30% @ [B]. 40% [C]. 50% [D]. 60% [E]. 70%
According to IS Code 1489-1991; ppc mixed least of 15-35 percent.
C.R.R.I. charts are used to obtain a relatioship between strength of concrete and
[A]. water cement ratio @ [B]. workability [C]. grading of aggregate [D]. fineness modulus [E]. none of these.
C.R.R.I - Central Road Research Institute.
The final operation of finishing floors, is known as
[A]. screeding [B]. floating [C]. trowelling @ [D]. finishing [E]. all the above.
TROWELLING : It is the final operation of finishing the concrete surface where smooth and dense surface required.
The maximum thickness of concrete floor of a cement warehouse, is
[A]. 10 cm [B]. 15 cm [C]. 20 cm [D]. 25 cm @ [E]. 30 cm
25 Cm is a correct answer because 15 cm is a minimum thickness of floor.
The light weight aggregates are obtained from
[A]. sedimentary rocks
[B]. metamorphic rocks
[C]. igneous rocks
[D]. volcanic source. @
Volcanic rock manufactured when melting magma comes on the top. The surface of the earth and deposited. Example basalt and trap.
And it is light in weight.
The datum temperature for maturity by Plowman, is
[A]. 23°C
[B]. 0°
[C]. - 5.6°C
[D]. - 11.7°C @
Plowman (1958) proposed a single strength-maturity equation based on past studies performed by various authors, with various mixtures, water-to-cement ratios, and curing temperatures between 11°F and 105°F (-12°C to 41°C). Using the logarithmic strength-maturity function, he proposed that the constants, a and b have specific values based on four strength ranges up to 10,000 psi. With this equation, Plowman found that any concrete strength could be estimated based on a given maturity, regardless of water-to-cement ratio, the curing temperature under 100°F, or aggregate-to-cement ratio, with an average error of 3%. Plowman’s equation seemed to be valid, although his equation was only based on 26 different compressive strength values.
Saw dust can be rendered chemically inert by boiling it in water containing
[A]. ferrous sulphate @ [B]. potassium chloride [C]. ammonia [D]. nitric acid [E]. sulphuric acid.
Saw dust can be rendered chemically inert by boiling it in water containing
[A]. ferrous sulphate @ [B]. potassium chloride [C]. ammonia [D]. nitric acid [E]. sulphuric acid.
The cement whose strength is a little lower than the ordinary cement during the first three months but attains afterwards the same strength, is known as
[A]. low-heat Portland cement @ [B]. rapid hardening Portland cement [C]. Portland blast slag cement [D]. Portland pozzolana cement [E]. none of these.
The cement whose strength is a little lower than the ordinary cement during the first three months but attains afterwards the same strength, is known as
[A]. low-heat Portland cement @ [B]. rapid hardening Portland cement [C]. Portland blast slag cement [D]. Portland pozzolana cement [E]. none of these.
Pick up the correct statement from the following:
[A]. Sand stones may be divided into calcareous, siliceous and ferrugineous sand stones
[B]. Concrete using sand stones, cracks due to excessive shrinkage
[C]. Very hard and close grained crystallined lime stones are suitable aggregates but provide low strength
[D]. Broken bricks produce a concrete having good fire resisting qualities
[E]. All the above. @
Pick up the correct statement from the following:
[A]. Sand stones may be divided into calcareous, siliceous and ferrugineous sand stones
[B]. Concrete using sand stones, cracks due to excessive shrinkage
[C]. Very hard and close grained crystallined lime stones are suitable aggregates but provide low strength
[D]. Broken bricks produce a concrete having good fire resisting qualities
[E]. All the above. @
