For the construction of thin R.C.C. structures, the type of cement to be avoided, is
Ordinary Portland cement
Rapid hardening cement
Low heat cement
Blast furnace slag cement
Correct Answer :
D. Blast furnace slag cement
Related Questions
Shrinkage in concrete can be reduced by using
Low water cement ratio
Less cement in the concrete
Proper concrete mix
All the above
Specified compressive strength of concrete is obtained from cube tests at the end of
3 days
7 days
21 days
28 days
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
The recommended value of modular ratio for reinforced brick work is
18
30
40
58
Concrete mainly consists of
Cement
Aggregates
Water
All the above
The process of hardening the concrete by keeping its surface moist is known
Placing
Wetting
Curing
Compacting
Construction joints are generally provided in concrete
Roads
Retaining walls
Lining of canals
All the above
While compacting the concrete by a mechanical vibrator, the slump should not exceed
2.5 cm
5.0 cm
7.5 cm
10 cm
Workability of concrete is directly proportional to
Aggregate cement ratio
Time of transit
Grading of the aggregate
All of above
The purpose of reinforcement in pre-stressed concrete is
To provide adequate bond stress
To resist tensile stresses
To impart initial compressive stress in concrete
All of the above
Pick up the correct statement from the following:
According to the petrological characteristics, concrete aggregates are classified as heavy weight, normal weight and light weight
According to the shape of the particles, concrete aggregates are classified as rounded irregular, angular and flaky
According to the surface texture of the particles, the concrete aggregates are classified as glassy, smooth, granular, rough, crystalline, honey combed and porous
All the above
The minimum cover to the ties or spirals should not be less than
15 mm
20 mm
25 mm
50 mm
Hydration of cement is due to chemical action of water with
Tricalcium silicate and dicalcium silicate
Dicalcium silicate and tricalcium aluminate
Tricalcium aluminate and tricalcium alumino ferrite
All the above
For batching 1:3:6 concrete mix by volume, the ingredients required per bag of 50 kg cement, are:
70 litres of sand and 120 litres of aggregates
70 kg of sand and 140 litres of aggregates
105 litres of sand and 140 litres of aggregates
105 litres of sand and 210 litres of aggregates
The ratio of the diameter of reinforcing bars and the slab thickness is
1/4
1/5
1/6
1/8
Pick up the correct statement from the following:
Higher workability indicates unexpected increase in the moisture content
Higher workability indicates deficiency of sand
If the concrete mix is dry, the slump is zero
All the above
The aggregate impact value of the aggregate used in
Building concrete is less than 45
Road pavement concrete is less than 30
Runway concrete is less than 30
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)
Permissible compressive strength of M 200 concrete grade is
100 kg/cm2
150 kg/cm2
200 kg/cm2
250 kg/cm2
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
A flaky aggregate is said to be elongated if its length is
Equal to the mean size
Twice the mean size
Thrice the mean size
Four times the mean size
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)
Permissible compressive strength of M 200 concrete grade is
100 kg/cm2
150 kg/cm2
200 kg/cm2
250 kg/cm2
Ratio of permissible stress in direct compression and bending compression is
Less than 1
Between 1 and 1.5
Between 1.5 and 2.0
Greater than 2
Sinking of an intermediate support of a continuous beam (i) Reduces the negative moment at support (ii) Increases the negative moment at support (iii) Reduces the positive moment at center of span (iv) Increases the positive moment at center of span The correct answer is
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
Expansion joints are provided if the length of concrete structures exceeds
10 m
15 m
15 m
45 m
In counterfort retaining walls, the main reinforcement in the stem at support is
Not provided
Provided only on inner face
Provided only on front face
Provided both on inner and front faces
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
Non-uniform compaction may cause the concrete
Porous
Non-homogeneous
Reduced strength
All the above
The bulk density of aggregates does not depend upon:
Size and shape of aggregates
Specific gravity of aggregates
Grading of aggregates
Size and shape of the container