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
Correct Answer :
D. All the above
Related Questions
Pick up the correct statement from the following:
The quality of water governs the strength of concrete
10% excess of water reduces the strength of concrete by 15%
30% excess of water reduces the strength of concrete by 50%
All the above
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
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
To minimise the effect of differential settlement, the area of a footing should be designed for
Dead load only
Dead load + live load
Dead load + fraction of live load
Live load + fraction of dead load
The strength and quality of concrete, depend upon:
Grading of aggregates
Surface area of aggregates
Shape of aggregates
All the above
The percentage of voids in cement is approximately
25 %
40 %
60 %
80 %
Shrinkage in concrete can be reduced by using
Low water cement ratio
Less cement in the concrete
Proper concrete mix
All the above
The void ratio of
Single size coarse aggregate is roughly 0.45
Graded coarse aggregate is roughly 0.040
Fine aggregate is roughly 0.45
All the above
Pick up the correct statement from the following:
Continuous grading is not necessary for obtaining a minimum of air voids
The omission of a certain size of aggregate is shown by a straight horizontal line on the grading curve
The omission of a certain size of aggregate in concrete increases the workability but also increases the liability to segregation
All the above
Poisson's ratio for concrete
Remains constant
Increases with richer mixes
Decreases with richer mixes
None of the above
Pick up the correct statement from the following:
An increase in water content must be accompanied by an increase in cement content
Angular and rough aggregates reduce the workability of the concrete
The slump of the concrete mix decreases due to an increase in temperature
All the above
Due to shrinkage stresses, a simply supported beam having reinforcement only at bottom tends to
Deflect downward
Deflect upward
Deflect downward or upward
None of the above
Slump test is done for
Clay
Sand
Lime
Concrete
Maximum quantity of water needed per 50 kg of cement for M 15 grade of concrete is
28 liters
30 liters
32 liters
34 liters
Sand generally contains salt if it is obtained from:
Nala beds
River beds
Sea beds
None of these
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
The compressive strength of 100 mm cube as compared to 150 mm cube is always
Less
More
Equal
None of the above
Admixtures which cause early setting and hardening of concrete are called
Workability admixtures
Accelerators
Retarders
Air entraining agents
Pick up the correct statement from the following:
Sand stones may be divided into calcareous, siliceous and ferruginous sand stones
Concrete using sand stones, cracks due to excessive shrinkage
Broken bricks produce a concrete having good fire resisting qualities
All the above
Critical section for shear in case of flat slabs is at a distance of
Effective depth of slab from periphery of column/drop panel
d/2 from periphery of column/capital/ drop panel
At the drop panel of slab
At the periphery of column
According to Whitney's theory, ultimate strain of concrete is assumed to be
0.03 %
0.1 %
0.3 %
3 %
Log Angles machine is used to test the aggregate for
Crushing strength
Impact value
Abrasion resistance
Water absorption
While compacting the concrete by a mechanical vibrator, the slump should not exceed
2.5 cm
5.0 cm
7.5 cm
10 cm
The bulk density of aggregates, is generally expressed as
Tonnes/cubic metre
kg/cubic metre
kg/litre
g/cm3
For a slab supported on its four edges with corners held down and loaded uniformly, the Marcus correction factor to the moments obtained by Grashoff Rankine's theory
Is always less than 1
Is always greater than 1
Can be more than 1
Can be less than 1
Curing
Reduces the shrinkage of concrete
Preserves the properties of concrete
Prevents the loss of water by evaporation
All of the above
Pick up the correct statement from the following:
Construction joints are necessarily planned for their locations
Expansion joints are provided to accommodate thermal expansion
Construction joints are provided to control shrinkage cracks
All the above
If the foundations of all the columns of a structure are designed on the total live and dead load basis, then
There will be no settlement of columns
There will be no differential settlement
The settlement of exterior columns will be more than interior columns
The settlement of interior columns will be more than exterior columns
Setting time of cement increases by adding
Gypsum
Hydrogen peroxide
Calcium chloride
Sodium oxide
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