Pick up the correct statement from the following:
Lime in excess, causes the cement to expand and disintegrate
Silica in excess, causes the cement to set slowly
Alumina in excess, reduces the strength of the cement
All the above
Correct Answer :
D. All the above
Related Questions
In case of hand mixing of concrete, the extra cement to be added is
5 %
10 %
15 %
20 %
Pick up the correct proportions of chemical ingredients of cement
Lime : Silica : Alumina : Iron oxide : 63 : 22 : 6 : 3
Silica : Lime : Alumina : Iron oxide : 63 : 22 : 6 : 3
Alumina : Silica : Lime : Iron oxide : 63 : 22 : 6 : 3
Iron oxide : Alumina : Silica : Lime : 63 : 22 : 6 : 3
An aggregate which passes through 25 mm I.S. sieve and is retained on 20 mm sieve, is said to be flaky if its least dimension is less than
22.5 mm
18.5 mm
16.5 mm
13.5 mm
Pozzolana cement is used with confidence for construction of
Dams
Massive foundations
R.C.C. structures
All the above
The final operation of finishing floors, is known as
Screeding
Floating
Trowelling
Finishing
Specified compressive strength of concrete is obtained from cube tests at the end of
3 days
7 days
21 days
28 days
Pick up the incorrect statement from the following:
Space between the exterior walls of a warehouse and bag piles should be 30 cm
Cement bags should preferably be piled on wooden planks
Width and height of the pile should not exceed 3 m and 2.70 m respectively
None of these
The load factors for live load and dead load are taken respectively as
1.5 and 2.2
2.2 and 1.5
1.5 and 1.5
2.2 and 2.2
1% of voids in a concrete mix would reduce its strength by about
5 %
10 %
15 %
20 %
Maximum percentage reinforcement in case of slabs is limited to
2
4
6
8
The cement becomes useless if its absorbed moisture content exceeds
1 %
2 %
3 %
5 %
Which of the following has high tensile strength?
Plain hot rolled wires
Cold drawn wires
Heat treated rolled wires
All have same tensile strength
Permissible compressive strength of M 200 concrete grade is
100 kg/cm2
150 kg/cm2
200 kg/cm2
250 kg/cm2
Pick up the incorrect statement from the following:
Tricalcium silicate (C3S) hydrates rapidly
Tricalcium silicate (C3S) generates more heat of hydration
Tricalcium silicate (C3S) develops early strength
Tricalcium silicate (C3S) has more resistance to sulphate attack
Workability of concrete is inversely proportional to
Time of transit
Water-cement ratio
The air in the mix
Size of aggregate
The maximum value of hoop compression in a dome is given by
wR / 4d
wR/2d
wR/d
2wR/d Where, w = load per unit area of surface of dome R = radius of curvature d = thickness of dome
The aggregate containing moisture in pores and having its surface dry, is known as
Moist aggregates
Very dry aggregates
Dry aggregates
Saturated surface dry aggregate
The strength of concrete after one year as compared to 28 days strength is about
10 to 15% more
15 to 20% more
20 to 25% more
25 to 50% more
Concrete containing
Siliceous aggregates, has higher co-efficient of expansion
Igneous aggregates, has intermediate coefficient of expansion
Lime stones, has lowest co-efficient of expansion
All the above
Non-uniform compaction may cause the concrete
Porous
Non-homogeneous
Reduced strength
All the above
The percentage of voids in cement is approximately
25 %
40 %
60 %
80 %
Ultimate strength of cold drawn high steel wires
Increases with increase in diameter of bar
Decreases with increase in diameter of bar
Does not depend on diameter of bar
None of the above
Which of the following R.C. retaining walls is suitable for heights beyond 6 m?
L-shaped wall
T-shaped wall
Counterfort type
All of the above
For the construction of cement concrete floor, the maximum permissible size of aggregate, is
4 mm
6 mm
8 mm
10 mm
Increase in the moisture content in concrete
Reduces the strength
Increases the strength
Does not change the strength
All of the above
For given workability the grading requiring the least amount of water is one that gives
Greatest surface area for the given cement and aggregates
Least surface area for the given cement and aggregates
Least weight for the given cement and aggregates
Greatest weight for the given cement and aggregates
Hardening of cement occurs at
Rapid rate during the first few days and afterwards it continues to increase at a decreased rate
Slow rate during the first few days and afterwards it continues to increase at a rapid rate
Uniform rate throughout its age
None of these
For the construction of the retaining structures, the type of concrete mix to be used, is
1 : 3 : 6
1 : 2 : 4
1 : 1 ½ : 3
1 : 4 : 8
For compacting plain concrete road surface of thickness less than 20 cm, we use
Internal vibrator
Screed vibrator
Form vibrator
None of these
Pick up the correct statement from the following:
The quality of water governs the strength of concrete
10% excess of water reduces the strength of concrete by 15%
30% excess of water reduces the strength of concrete by 50%
All the above