The effect of adding calcium chloride in concrete is (i) To increase shrinkage (ii) To decrease shrinkage (iii) To increase setting time (iv) To decrease setting time The correct answer is
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
Correct Answer :
B. (i) and (iv)
Related Questions
Vicat's apparatus is used for
Fineness test
Consistency test
Setting time test
Soundness test
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
The type of aggregates of same nominal size, which contain less voids when compacted, are
Rounded spherical
Irregular
Flaky
None of these
Le-Chatelier's apparatus is used for testing
Soundness of cement
Hardness of cement
Strength of cement
Durability of cement
If a beam fails in bond, then its bond strength can be increased most economically by
Increasing the depth of beam
Using thinner bars but more in number
Using thicker bars but less in number
Providing vertical stirrups
In counterfort retaining walls, the main reinforcement in the stem at support is
Not provided
Provided only on inner face
Provided only on front face
Provided both on inner and front faces
If the engineer-in-charge approves, the 10 cm cubes may be used for the work test of concrete provided maximum nominal size of aggregate, does not exceed
10 cm
15 cm
20 cm
25 cm
Water required per bag of cement, is
7 kg
14 kg
21 kg
35 kg
If X, Y and Z are the fineness modulli of coarse, fine and combined aggregates, the percentage (P) of fine aggregates to combined aggregates, is
P = [(Z - X)/(Z - Y)] × 100
P = [(X - Z)/(Z - Y)] × 100
P = [(X - Z)/(Z + Y)] × 100
P = [(Z + X)/(Z - Y)] × 100
For compacting plain concrete road surface of thickness less than 20 cm, we use
Internal vibrator
Screed vibrator
Form vibrator
None of these
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
Inert material of a cement concrete mix, is
Water
Cement
Aggregate
None of these
According to IS: 4561978, the maximum reinforcement in a column is
2 %
4 %
6 %
8 %
The purpose of reinforcement in pre-stressed concrete is
To provide adequate bond stress
To resist tensile stresses
To impart initial compressive stress in concrete
All of the above
Examine the following statements: (i) Factor of safety for steel should be based on its yield stress, (ii) Factor of safety for steel should be based on its ultimate stress, (iii) Factor of safety for concrete should be based on its yield stress, (iv) Factor of safety for concrete should be based on its ultimate stress. The correct statements are
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
If the effective plan area of a warehouse is 54 sq. m, and maximum height of piles permitted is 270 cm, the number of cement bags to be stored, is
2000 bags
2200 bags
2400 bags
2700 bags
If the various concrete ingredients i.e. cement, sand and aggregates are in the ratio of 1:3:6, the grade of concrete, is
M 100
M 150
M 200
M 250
Under normal conditions using an ordinary cement, the period of removal of the form work, is:
7 days for beam soffits
14 days for bottom slabs of spans 4.6 m and more
21 days for bottom beams over 6 m spans
All the above
An excess of flaky particles in concrete aggregates
Decreases the workability
Increases the quantity of water and sand
More than 15% are not desirable
All the above
For the construction of cement concrete dams, the maximum permissible size of the aggregates, is
40 mm
50 mm
60 mm
70 mm
Concrete mainly consists of
Cement
Aggregates
Water
All the above
Due to circumferential action of the spiral in a spirally reinforced column
Capacity of column is decreased
Ductility of column reduces
Capacity of column is decreased but ductility of column increases
Both the capacity of column and ductility of column increase
To obtain cement dry powder, lime stones and shales or their slurry, is burnt in a rotary kiln at a temperature between
1100° and 1200°C
1200° and 1300°C
1300° and 1400°C
1400° and 1500°C
In a spherical dome subjected to concentrated load at crown or uniformly distributed load, the meridional force is always
Zero
Tensile
Compressive
Tensile or compressive
The compressive strength of 100 mm cube as compared to 150 mm cube is always
Less
More
Equal
None of the above
The property of the ingredients to separate from each other while placing the concrete is called
Segregation
Compaction
Shrinkage
Bulking
Water cement ratio is generally expressed in volume of water required per
10 kg
20 kg
30 kg
50 kg
For an ordinary Portland cement
Residual does not exceed 10% when sieved through IS Sieve No. 9
Soundness varies from 5 to 10 mm
Initial setting time is not less than 30 minutes
Compressive stress after 7 days, is not less than 175 kg/cm2
High temperature
Increases the strength of concrete
Decreases the strength of concrete
Has no effect on the strength of concrete
None of these
For walls, columns and vertical faces of all structural members, the form work is generally removed after
24 to 48 hours
3 days
7 days
14 days