An excess of flaky particles in concrete aggregates
Decreases the workability
Increases the quantity of water and sand
More than 15% are not desirable
All the above
Correct Answer :
D. All the above
Related Questions
Construction joints are generally provided in concrete
Roads
Retaining walls
Lining of canals
All the above
Particles of 0.002 mm size are that of
Clay
Sand
Gravel
None of these
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:
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
If X, Y and Z are the fineness modulli of coarse, fine and combined aggregates, the percentage (P) of fine aggregates to combined aggregates, is
P = [(Z - X)/(Z - Y)] × 100
P = [(X - Z)/(Z - Y)] × 100
P = [(X - Z)/(Z + Y)] × 100
P = [(Z + X)/(Z - Y)] × 100
To prevent segregation, the maximum height for placing concrete, is
100 cm
125 cm
150 cm
200 cm
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
M 150 grade of concrete approximates
1 : 3 : 6 mix
1 : 1 :2 mix
1 : 2 : 4 mix
1 : 1.5 : 3 mix
Pick up the correct statement from the following:
Lime in excess, causes the cement to expand and disintegrate
Silica in excess, causes the cement to set slowly
Alumina in excess, reduces the strength of the cement
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
Strength of concrete with passage of time
Increases
Decreases
Fluctuates
Remains constant
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
For construction of structures in sea water, the cement generally preferred to, is
Portland-pozzolana cement
Quick setting cement
Low heat Portland cement
Rapid hardening cement
If the slump of a concrete mix is 60 mm, its workability is
Very low
Low
Medium
High
On a grading curve, the gap grading is represented by
A horizontal line
A vertical line
N.W. inclined line
N.E. inclined line
The most useless aggregate is one whose surface texture is
Smooth
Granular
Glassy
Honey combed and porous
In a ring beam subjected to uniformly distributed load (i) Shear force at mid span is zero (ii) Shear force at mid span is maximum (iii) Torsion at mid span is zero (iv) Torsion at mid span is maximum The correct answer is
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
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
Non-uniform compaction may cause the concrete
Porous
Non-homogeneous
Reduced strength
All the above
For quality control of Portland cement, the test essentially done is
Setting time
Tensile strength
Consistency
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
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
The percentage of the aggregate of F.M. 2.6 to be combined with coarse aggregate of F.M. 6.8 for obtaining the aggregates of F.M. 5.4, is
30 %
40 %
50 %
60 %
Water cement ratio is
Volume of water to that of cement
Weight of water to that of cement
Weight of concrete to that of water
Both (a) and (b) of the above
Too wet concrete may cause
Weakness of concrete
Excessive laitance
Segregation
All the above
In the design of a front counterfort in a counterfort retaining wall, the main reinforcement is provided on (i) Bottom face near counterfort (ii) Top face near counterfort (iii) Bottom face near centre of span (iv) Top face near centre of span The correct answer is
Only (i)
Only (ii)
Both (i) and (iv)
Both (ii) and (iii)
Pozzolanic properties exist in
Shales
Fly ash
Pumicite
All the above
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
In a spherical dome subjected to concentrated load at crown or uniformly distributed load, the meridional force is always
Zero
Tensile
Compressive
Tensile or compressive
In order to obtain the best workability of concrete, the preferred shape of aggregate is
Rounded
Elongated
Angular
All of the above