Which of the following losses of pre-stress occurs only in pretensioning and not in post-tensioning?
Elastic shortening of concrete
Shrinkage of concrete
Creep of concrete
Loss due to friction
Correct Answer :
A. Elastic shortening of concrete
Related Questions
A higher modular ratio shows
Higher compressive strength of concrete
Lower compressive strength of concrete
Higher tensile strength of steel
Lower tensile strength of steel
The minimum cover to the ties or spirals should not be less than
15 mm
20 mm
25 mm
50 mm
If 50 kg of fine aggregates and 100 kg of coarse aggregates are mixed in a concrete whose water cement ratio is 0.6, the weight of water required for harsh mix, is
8 kg
10 kg
12 kg
14 kg
To hydrate 500kg of cement full water needed, is
100 kg
110 kg
120 kg
130 kg
For the construction of cement concrete floor, the maximum permissible size of aggregate, is
4 mm
6 mm
8 mm
10 mm
Proper batching ensures
Economy
Durability
Workability
All the above
The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by
fcr - fcs = fcl
fcr > fcs > fcl
fcr < fcs < fcl
fcs > fcr > fcl
Slump test is done for
Clay
Sand
Lime
Concrete
The commercial name of white and coloured cement in India, is
Colorcrete
Silvicrete
Snowcem
All the above
In symmetrically reinforced sections, shrinkage stresses in concrete and steel are respectively
Compressive and tensile
Tensile and compressive
Both compressive
Both tensile
The ratio of the diameter of reinforcing bars and the slab thickness is
1/4
1/5
1/6
1/8
Cube strength of controlled concrete to be used for pre-tensioned and post-tensioned work respectively should not be less than
35 MPa and 42 MPa
42 MPa and 35 MPa
42 MPa and 53 MPa
53 MPa and 42 MPa
Sand generally contains salt if it is obtained from:
Nala beds
River beds
Sea beds
None of these
Strength of concrete with passage of time
Increases
Decreases
Fluctuates
Remains constant
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
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)
Construction joints are generally provided in concrete
Roads
Retaining walls
Lining of canals
All the above
The ratio of the length to breadth of a wooden float, is
4.5
5.5
6.5
7.5
For the design of retaining walls, the minimum factor of safety against overturning is taken as
1.5
2.0
2.5
3.0
For concreting tunnel linings, transportation of concrete is done by
Pans
Wheel borrows
Containers
Pumps
The increased cohesiveness of concrete, makes it
Less liable to segregation
More liable to segregation
More liable to bleeding
More liable for surface scaling in frosty weather
After casting, an ordinary cement concrete on drying
Expands
Mix
Shrinks
None of these
Slump test of concrete is a measure of its
Consistency
Compressive strength
Tensile strength
Impact value
Vicat apparatus is used for
Fineness test
Consistency test
Test for setting time
Test for tensile strength
The load carrying capacity of a helically reinforced column as compared to that of a tied column is about
5 % less
10 % less
5 % more
10 % more
For given water content, workability decreases if the concrete aggregates contain an excess of
Thin particles
Flat particles
Elongated particles
All the above
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
Pozzolanic properties exist in
Shales
Fly ash
Pumicite
All the above
The aggregate impact value of the aggregate used in
Building concrete is less than 45
Road pavement concrete is less than 30
Runway concrete is less than 30
All the above
Particles of 0.002 mm size are that of
Clay
Sand
Gravel
None of these