Workability of concrete for a given water content is good if the aggregates, are
Rounded aggregate
Irregular aggregate
Angular aggregate
Flaky aggregates
Correct Answer :
A. Rounded aggregate
Related Questions
Curing of pavements, floors, roofs and slabs, is done by
Membrane method
Ponding method
Covering surface with bags
Sprinkling water method
Pick up the correct statement from the following:
The concrete gains strength due to hydration of cement
The concrete does not set at freezing point
The strength of concrete increases with its age
All the above
Workability of concrete mix with low water cement ratio is determined by
Tensile strength test
Slump test
Compaction factor test
Flexural strength test
If 1500 g of water is required to have a cement paste 1875 g of normal consistency, the percentage of water is,
20 %
25 %
30 %
35 %
Pick up the incorrect statement from the following:
A rich mix of concrete possesses higher strength than that a lean mix of desired workability with excessive quantity of water
The strength of concrete decreases as the water cement ratio increases
Good compaction by mechanical vibrations, increases the strength of concrete
None of these
The main reason for providing number of reinforcing bars at a support in a simply supported beam is to resist in that zone
Compressive stress
Shear stress
Bond stress
Tensile stress
Pick up the correct statement from the following:
Insufficient quantity of water makes the concrete mix harsh
Insufficient quantity of water makes the concrete unworkable
Excess quantity of water makes the concrete segregated
All the above
To hydrate 500kg of cement full water needed, is
100 kg
110 kg
120 kg
130 kg
According to Whitney's theory, depth of stress block for a balanced section of a concrete beam is limited to
0.43 d
0.537 d
0.68 d
0.85 d Where d is effective depth of beam
Proper proportioning of concrete, ensures
Desired strength and workability
Desired durability
Water tightness of the structure
All the above
The top diameter, bottom diameter and the height of a slump mould are:
10 cm, 20 cm, 30 cm
10 cm, 30 cm, 20 cm
20 cm, 10 cm, 30 cm
20 cm, 30 cm, 10 cm
According to I.S. : 456, the number of grades of concrete mixes, is
3
4
5
7
Select the incorrect statement
Lean mixes bleed more as compared to rich ones.
Bleeding can be minimized by adding pozzolana finer aggregate
Bleeding can be increased by addition 'of calcium chloride
None of the above
Which of the following has high tensile strength?
Plain hot rolled wires
Cold drawn wires
Heat treated rolled wires
All have same tensile strength
To obtain cement dry powder, lime stones and shales or their slurry, is burnt in a rotary kiln at a temperature between
1100° and 1200°C
1200° and 1300°C
1300° and 1400°C
1400° and 1500°C
The concrete mix which causes difficulty in obtaining a smooth finish, possess
Segregation
Internal friction
Hardness
Bleeding
Segregation is responsible for
Honey-combed concrete
Porous layers in concrete
Surface scaling in concrete
All the above
Concrete gains strength due to
Chemical reaction of cement with sand and coarse aggregates
Evaporation of water from concrete
Hydration of cement
All the above
The bulk density of aggregates, depends upon
Shape
Grading
Compaction
All the above
The commercial name of white and coloured cement in India, is
Colorcrete
Silvicrete
Snowcem
All the above
'Ware house pack' of cement means
Full capacity of the ware house
Pressure exertion of the bags of upper layers
Pressure compaction of the bags on lower layers
Packing the ware house
The bulk density of aggregates, is generally expressed as
Tonnes/cubic metre
kg/cubic metre
kg/litre
g/cm3
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
Tricalcium aluminate (C3A)
Reacts fast with water
Generates less heat of hydration
Causes initial setting and early strength of cement
Does not contribute to develop ultimate strength
Pick up the incorrect statement from the following:
The bottom and top ends of slump mould are parallel to each other
The axis of the mould is perpendicular to the end faces
The internal surface of the mould is kept clean and free from set cement
The mould is in the form of a frustum of hexagonal pyramid
The risk of segregation is more for
Wetter mix
Larger proportion of maximum size aggregate
Coarser grading
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
In case of hand mixing of concrete, the extra cement to be added is
5 %
10 %
15 %
20 %
In counterfort type retaining walls (i) The vertical slab is designed as a continuous slab (ii) The heel slab is designed as a continuous slab (iii) The vertical slab is designed as a cantilever (iv) The heel slab is designed as a cantilever The correct answer is
(i) and (ii)
(i)and(iv)
(ii) and (iii)
(iii) and (iv)
Which of the following statements is incorrect?
Higher Vee-Bee time shows lower workability
Higher slump shows higher workability
Higher compacting factor shows higher workability
None of the above