The process of mixing, transporting, placing and compacting concrete using Ordinary Port land Cement should not take more than
30 minutes
40 minutes
60 minutes
90 minutes
Correct Answer :
A. 30 minutes
Related Questions
An aggregate is said to be flaky if its least dimension is less than
1/5th of mean dimension
2/5th of mean dimension
3/5th of mean dimension
4/5th of mean dimension
Normally pre-stressing wires are arranged in the
Upper part of the beam
Lower part of the beam
Center
Anywhere
If the permissible stress in steel in tension is 140 N/mm², then the depth of neutral axis for a singly reinforced rectangular balanced section will be
0.35 d
0.40 d
0.45 d
Dependent on grade of concrete also
To obtain a very high strength concrete, use very fine grained
Granite
Magnetite
Barite
Volcanic scoria
Pick up the correct statement from the following:
The weight of ingredients of concrete mix, is taken in kilograms
Water and aggregates are measured in litres
20 bags of cement make one tonne
All the above
The compaction of concrete, improves
Density
Strength
Durability
All the above
The dimensions of a 35 litre forma for measuring aggregates by volume, are:
Length 30 cm, breadth 25 cm, height 30 cm
Length 39 cm, breadth 25 cm, height 32 cm
Length 27 cm, breadth 27 cm, height 48 cm
Length 220 cm, breadth 25 cm, height 40 cm
Separation of water or water sand cement from a freshly concrete, is known
Bleeding
Creeping
Segregation
Flooding
Ratio of permissible stress in direct compression and bending compression is
Less than 1
Between 1 and 1.5
Between 1.5 and 2.0
Greater than 2
Maximum distance between expansion joints in structures as per IS: 456 1978 is
20 m
30 m
45 m
60 m
The minimum cover to the ties or spirals should not be less than
15 mm
20 mm
25 mm
50 mm
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
According to Water-Cement Ratio Law, the strength of workable plastic concrete
Depends upon the amount of water used in the mix
Does not depend upon the quality of cement mixed with aggregates
Does not depend upon the quantity of cement mixed with aggregates
All the above
Pick up the incorrect statement from the following:
In properly graded aggregates, bulk density is more
In single size aggregates, bulk density is least
In single size aggregates, bulk density is maximum
None of these
To prevent segregation, the maximum height for placing concrete, is
100 cm
125 cm
150 cm
200 cm
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
Proper batching ensures
Economy
Durability
Workability
All the above
Minimum thickness of load bearing RCC wall should be
50 mm
100 mm
150 mm
200 mm
Minimum grade of concrete to be used in reinforced concrete as per IS: 4561978 is
M 15
M 20
M 10
M 25
Pick up the correct statement from the following:
Higher workability indicates unexpected increase in the moisture content
Higher workability indicates deficiency of sand
If the concrete mix is dry, the slump is zero
All the above
To hydrate 500kg of cement full water needed, is
100 kg
110 kg
120 kg
130 kg
Vicat apparatus is used for
Fineness test
Consistency test
Test for setting time
Test for tensile strength
The condition not applicable to water cement ratio law, is
Internal moisture conditions on hydration continue till complete strength is gained
Concrete specimens may be tested at any temperature
Concrete specimens need be of same age
Concrete specimens need be of same size
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
Slump test of concrete is a measure of its
Consistency
Compressive strength
Tensile strength
Impact value
For preparing a test-specimen, it is necessary
To mix cement and fine aggregate by dry hand
To mix coarse aggregates
To mix water to the cement, fine aggregates and coarse aggregates
All the above
The cement becomes useless if its absorbed moisture content exceeds
1 %
2 %
3 %
5 %
For given water content, workability decreases if the concrete aggregates contain an excess of
Thin particles
Flat particles
Elongated particles
All the above
In a ring beam subjected to uniformly distributed load (i) Shear force at mid span is zero (ii) Shear force at mid span is maximum (iii) Torsion at mid span is zero (iv) Torsion at mid span is maximum The correct answer is
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
Construction joints are provided
Where B.M. and S.F. are small
Where the member is supported by other member
At 18 m apart in huge structures
All the above