6 mm
8 mm
12 mm
16 mm
C. 12 mm
30 minutes
40 minutes
60 minutes
90 minutes
15 mm
25 mm
30 mm
40 mm
1 : 3 : 6
1 : 2 : 4
1 : 1 ½ : 3
1 : 4 : 8
Chemical reaction of cement with sand and coarse aggregates
Evaporation of water from concrete
Hydration of cement
All the above
Increases the strength of concrete
Decreases the strength of concrete
Has no effect on the strength of concrete
None of these
Ferrous sulphate
Potassium chloride
Ammonia
Nitric acid
Colour
Strength
Controlling setting time
None of these
23°C
0°
- 5.6°C
- 11.7°C
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
Smaller creep and shrinkage
Greater density and smaller permeability
Improved frost resistance
All the above
600 mm
750 mm
900 mm
More than 1 m
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
Extremely low
Very low
Low
High
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
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
1/5th of mean dimension
2/5th of mean dimension
3/5th of mean dimension
4/5th of mean dimension
Less water
Fine aggregates
Rich mix
More water and coarse aggregates
100 kg/cm2
150 kg/cm2
200 kg/cm2
250 kg/cm2
Weakness of concrete
Excessive laitance
Segregation
All the above
0.75 - 0.80
0.80 - 0.85
0.85 - 0.92
Above 0.92
Gypsum
Calcium chloride
Sodium silicate
All of the above
5% by weight of aggregates plus 20% of weight of cement
10% by weight of aggregates plus 10% of weight of cement
5% by weight of aggregates plus 30% of weight of cement
30% by weight of aggregates plus 10% of weight of cement
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
Compressive stress
Shear stress
Bond stress
Tensile stress
Membrane method
Ponding method
Covering surface with bags
Sprinkling water method
Between 150 to 300 kg/cm2
Between 350 to 600 kg/cm2
Between 150 to 500 kg/cm2
Below 200 kg/cm2
0.367 xu
0.416 xu
0.446 xu
0.573 xu
Building concrete is less than 45
Road pavement concrete is less than 30
Runway concrete is less than 30
All the above
7.30
7.35
7.40
7.45
One cantilever
Two cantilevers
Three cantilevers
Four cantilevers