Internal friction between the ingredients of concrete, is decreased by using
Less water
Fine aggregates
Rich mix
More water and coarse aggregates
Correct Answer :
D. More water and coarse aggregates
Related Questions
To hydrate 500kg of cement full water needed, is
100 kg
110 kg
120 kg
130 kg
Shrinkage of concrete depends upon
(i) Humidity of atmosphere
(ii) Passage of time
(iii) Stress The correct answer is
(i) and (ii)
(ii) and (iii)
Only (iii)
All (i), (ii) and (iii)
The fineness modulus of fine aggregate is in the range of
2.0 to 3.5
3.5 to 5.0
5.0 to 7.0
6.0 to 8.5
Shrinkage in concrete can be reduced by using
Low water cement ratio
Less cement in the concrete
Proper concrete mix
All the above
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
If a grading curve is horizontal between the portions of 20 mm I.S. Sieve and 4.75 mm I.S. Sieve, the graded aggregates do not contain
20 mm particles
10 mm particles
4.75 mm particles
All the above
The high strength of rapid hardening cement at early stage, is due to its
Finer grinding
Burning at high temperature
Increased lime cement
Higher content of tricalcium
Pick up the correct statement from the following:
High percentage of C3S and low percentage of C2S cause rapid hardening
High percentage of C3S and low percentage of C2S make the cement less resistive to chemical attack
Low percentage of C3S and high percentage of C2S contribute to slow hardening
All the above
The surface where two successive placements of concrete meet, is known as
Contraction joint
Expansion joint
Construction joint
Both (a) and (b)
The impurity of mixing water which affects the setting time and strength of concrete, is
Sodium sulphates
Sodium chlorides
Sodium carbonates and bicarbonates
Calcium bicarbonates
As compared to ordinary Portland cement, use of pozzolana cement
Reduces workability
Increases bleeding
Increases shrinkage
Increases strength
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)
Pick up the correct statement from the following:
The concrete gains strength due to hydration of cement
The concrete does not set at freezing point
The strength of concrete increases with its age
All the above
The following proportion of the ingredients of concrete mix, is not in conformation to arbitrary method of proportioning
1 : 1 : 2
1 : 2 : 4
1 : 3 : 6
1 : 4 : 10
The top diameter, bottom diameter and the height of a slump mould are:
10 cm, 20 cm, 30 cm
10 cm, 30 cm, 20 cm
20 cm, 10 cm, 30 cm
20 cm, 30 cm, 10 cm
A concrete using an air entrained cement
Has strength less than 10% to 15%
Has more resistance to weathering
Is more plastic and workable
Is free from segregation and bleeding
The specifications of a cement bag for storage, are
Weight 50 kg
Height 18 cm
Plan area 3000 sq. cm
All the above
Maximum percentage reinforcement in case of slabs is limited to
2
4
6
8
Pick up the correct statement from the following:
According to the petrological characteristics, concrete aggregates are classified as heavy weight, normal weight and light weight
According to the shape of the particles, concrete aggregates are classified as rounded irregular, angular and flaky
According to the surface texture of the particles, the concrete aggregates are classified as glassy, smooth, granular, rough, crystalline, honey combed and porous
All 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
Grading of sand causes great variation in
Workability of concrete
Strength of concrete
Durability of concrete
All the above
The ratio of the length to breadth of a wooden float, is
4.5
5.5
6.5
7.5
Higher workability of concrete is required if the structure is
Made with cement concrete
Thick and reinforced
Thin and heavily reinforced
Thick and heavily reinforced
Too wet concrete may cause
Weakness of concrete
Excessive laitance
Segregation
All the above
The strength and quality of concrete, depend upon:
Grading of aggregates
Surface area of aggregates
Shape of aggregates
All the above
Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete. If the compaction factor (Wp/Wf) is 0.95, the workability of concrete is
Extremely low
Very low
Low
High
Construction joints are generally provided in concrete
Roads
Retaining walls
Lining of canals
All the above
High temperature
Increases the strength of concrete
Decreases the strength of concrete
Has no effect on the strength of concrete
None of these
Expansion joints are provided if the length of concrete structures exceeds
10 m
15 m
15 m
45 m
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