Too wet concrete may cause
Weakness of concrete
Excessive laitance
Segregation
All the above
Correct Answer :
D. All the above
Related Questions
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
During erection, the pile of length l is supported by a crane at a distance of
0.207 l
0.293 l
0.707 l
0.793 l From the driving end of pile which rests on the ground
Pick up the correct statement from the following:
Segregation is necessary for a workable concrete
Consistency does not affect the workability of concrete
If the concrete mix is dry, the slump is maximum
None of these
Horizontal construction joints in concrete walls are generally provided at
Soffit level
Window sill level
Floor level
All the above
I.S. Sieve Nos. 10 mm and 4.75 mm are generally used for grading of
Coarse aggregates
Fine aggregates
Neither (a) nor (b)
Both (a) and (b)
The diameter of ties in a column should be
More than or equal to one fourth of diameter of main bar
More than or equal to 5 mm
More than 5 mm but less than one-fourth of diameter of main bar
More than 5 mm and also more than one-fourth of diameter of main bar
The specifications of a cement bag for storage, are
Weight 50 kg
Height 18 cm
Plan area 3000 sq. cm
All the above
Workability improved by adding
Fly ash
Hydrated lime
Calcium chloride
All the above
Pre-stress loss due to friction occurs
Only in post-tensioned beams
Only in pre-tensioned beams
In both post-tensioned and pre-tensioned beams
None of the above
Select the incorrect statement
Lean mixes bleed more as compared to rich ones.
Bleeding can be minimized by adding pozzolana finer aggregate
Bleeding can be increased by addition 'of calcium chloride
None of the above
In a counterfort retaining wall, the main reinforcement is provided on the (i) Bottom face in front counterfort (ii) Inclined face in front counterfort (iii) Bottom face in back counterfort (iv) Inclined face in back counterfort The correct answer is
(i) and (ii),
(ii) and (iii)
(i) and (iv)
(iii) and (iv)
Which of the following has high tensile strength?
Plain hot rolled wires
Cold drawn wires
Heat treated rolled wires
All have same tensile strength
For preparing ordinary concrete, the quantity of water used, is
5% by weight of aggregates plus 20% of weight of cement
10% by weight of aggregates plus 10% of weight of cement
5% by weight of aggregates plus 30% of weight of cement
30% by weight of aggregates plus 10% of weight of cement
The depth of footing for an isolated column is governed by (i) Maximum bending moment (ii) Shear force (iii) Punching shear The correct answer is
Only (i)
(i) and (ii)
(i) and (iii)
All (i), (ii) and (iii)
For batching 1:3:6 concrete mix by volume, the ingredients required per bag of 50 kg cement, are:
70 litres of sand and 120 litres of aggregates
70 kg of sand and 140 litres of aggregates
105 litres of sand and 140 litres of aggregates
105 litres of sand and 210 litres of aggregates
The grade of concrete M 150 means that compressive strength of a 15 cm cube after 28 days, is
100 kg/cm2
150 kg/cm2
200 kg/cm2
250 kg/cm2
Pozzolana cement is used with confidence for construction of
Dams
Massive foundations
R.C.C. structures
All the above
The commonly used material in the manufacture of cement is
Sand stone
Slate
Lime stone
Graphite
The main reason for providing number of reinforcing bars at a support in a simply supported beam is to resist in that zone
Compressive stress
Shear stress
Bond stress
Tensile stress
The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called
Segregation
Bleeding
Bulking
Creep
The most commonly used admixture which prolongs the setting and hardening time is
Gypsum
Calcium chloride
Sodium silicate
All of the above
Pick up the correct statement from the following:
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
The total water is the free water and the amount actually absorbed by the aggregates
Neither (a) nor (b)
Both (a) and (b)
For a concrete mix 1:3:6 and water cement ratio 0.6 both by weight, the quantity of water required per bag, is
10 kg
12 kg
14 kg
16 kg
Specified compressive strength of concrete is obtained from cube tests at the end of
3 days
7 days
21 days
28 days
According to ISI recommendations, the maximum depth of stress block for balanced section of a beam of effective depth d is
0.43 d
0.55 d
0.68 d
0.85 d
The risk of segregation is more for
Wetter mix
Larger proportion of maximum size aggregate
Coarser grading
All the above
The compressive strength of 100 mm cube as compared to 150 mm cube is always
Less
More
Equal
None of the above
Pick up the incorrect statement from the following. While performing preliminary test on concrete
Proportions of the material and water should be the same as to be used at the work site
Cement should be mixed by hand in order to maintain uniformity
Concrete mix should be stored in air-tight containers
Concrete ingredients should be kept at a temperature of 37° ± 2°C
For quality control of Portland cement, the test essentially done is
Setting time
Tensile strength
Consistency
All the above
1% of voids in a concrete mix would reduce its strength by about
5 %
10 %
15 %
20 %