After casting, an ordinary cement concrete on drying
Expands
Mix
Shrinks
None of these
Correct Answer :
C. Shrinks
Related Questions
An aggregate is said to be flaky, if its least dimension is less than
2/3 mean dimension
3/4 mean dimension
3/5 mean dimension
5/8 mean dimension
Select the incorrect statement
The loss of pre-stress is more in pre-tensioning system than in posttensioning system.
Pre-tensioning system has greater certainty about its durability.
For heavy loads and large spans in buildings or bridges, posttensioning system is cheaper than pre-tensioning system
None of 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
Le-Chatelier's apparatus is used for testing
Soundness of cement
Hardness of cement
Strength of cement
Durability of cement
The ratio of various ingredients (cement, sand, aggregates) in concrete of grade M 200, is
1 : 2 : 4
1 : 3 : 6
1 : 1 ½ : 3
1 : 1 : 2
To ensure constant moisture content in aggregates
Area of each aggregate pile should be large
Height of each aggregate pile should not exceed 1.50 m
Aggregate pile should be left for 24 hours before aggregates are used
All the above
If fineness modulus of sand is 2.5, it is graded as
Very fine sand
Fine sand
Medium sand
Coarse sand
A concrete having a slump of 6.5 cm, is said to be
Dry
Earth moist
Semi-plastic
Plastic
Pozzolana cement is used with confidence for construction of
Dams
Massive foundations
R.C.C. structures
All the above
The commercial name of white and coloured cement in India, is
Colorcrete
Silvicrete
Snowcem
All the above
As compared to ordinary Portland cement, high alumina cement has
Higher initial setting time but lower final setting time
Lower initial setting time but higher final setting time
Higher initial and final setting times
Lower initial and final setting times
Segregation is responsible for
Honey-combed concrete
Porous layers in concrete
Surface scaling in concrete
All the above
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
Gypsum is added for
Colour
Strength
Controlling setting time
None of these
The operation of removing humps and hollows of uniform concrete surface, is known as
Floating
Screeding
Trowelling
Finishing
The factor of safety for
Steel and concrete are same
Steel is lower than that for concrete
Steel is higher than that for concrete
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:
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
Pick up the correct statement from the following:
The free water is the amount of water added while mixing and the amount of water held on the surface of the aggregates prior to mixing
The total water is the free water and the amount actually absorbed by the aggregates
Neither (a) nor (b)
Both (a) and (b)
Too wet concrete may cause
Weakness of concrete
Excessive laitance
Segregation
All the above
For the construction of the retaining structures, the type of concrete mix to be used, is
1 : 3 : 6
1 : 2 : 4
1 : 1 ½ : 3
1 : 4 : 8
Allowable shear strength of concrete, depends upon
Shear strength
Tensile strength
Compressive strength
None of these
Pick up the incorrect statement from the following:
With passage of time, the strength of cement increases
With passage of time, the strength of cement decreases
After a period of 24 months, the strength of cement reduces to 50%
The concrete made with storage deteriorated cement, gains strength with time
An ordinary Portland cement when tested for its fineness, should not leave any residue on I.S. sieve No. 9, more than
5 %
10 %
15 %
20 %
Air entrainment in the concrete increases
Workability
Strength
The effects of temperature variations
The unit weight
Assertion A : The load factor for live load is greater than that for dead load. Reason R : The live loads are more uncertain than dead loads. Select your answer based on the coding system given below:
Both A and R is true and R is the correct explanation of A
Both A and R is true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than the diameter of bar nor less than
15 mm
25 mm
30 mm
40 mm
The 28 days cube strength of mass concrete using aggregates of maximum size 5 cm for gravity dams should be
Between 150 to 300 kg/cm2
Between 350 to 600 kg/cm2
Between 150 to 500 kg/cm2
Below 200 kg/cm2
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
The permissible diagonal tensile stress in reinforced brick work is
About 0.1 N/mm²
Zero
0.3 N/mm² to 0.7 N/mm²
About 1.0 N/mm²