This set of Basic Civil Engineering online test focuses on “Tests on Concrete”.
1. Modulus of elasticity, E is calculated using:
Explanation: The modulus of elasticity is found out to determine plastic or elastic nature of concrete. In the formula, fck is the characteristic strength.
Explanation: In slump test, fresh concrete is filled in a slump cone and it is taken off. The shape of the so formed concrete is represented in the figure above. The concrete has completely collapsed, hence the name.
3. Tensile strength is found out using:
b) Gradual tensile test
c) Split tensile test
d) Radial tensile test
Explanation: In addition to using characteristic strength fck to determine tensile strength, split tensile test can also be used. It is performed using a UTM.
4. Flexure strength is determined as:
a) Modulus of rigidity
b) Modulus of rupture
c) Modulus of plasticity
d) Modulus of elasticity
Explanation: Flexure strength of concrete is defined as the tensile strength of extreme fibre of plain concrete beam. It is determined in terms of modulus of rupture.
5. Compaction factor for heavily reinforced section with vibration is:
Explanation: Compaction factor test is conducted to determine the compaction factor. It has different values required for different purposes. To concrete a heavily reinforced section with vibration it is 0.85-0.92.
Explanation: The time is tested is Vee-Bee test. Time required to complete remoulding of concrete when subjected to the vibration is measured. It is then expressed in seconds.
7. The size of commonly used specimen for compression test is:
a) 50×30 mm
b) 150x150x150 mm
c) 150x50x50 mm
d) 150×150 mm
Explanation: The commonly used specimen to test compressive strength is a cube. It has 3 dimensions-length, width and height. These cubes are cast in moulds of size 150x150x150mm.
8. Concrete is filled in how many layers in slump cone in slump test.
Explanation: The fresh concrete is filled in slump cone in 4 layers. Each layer is tamped 25 times with a 16mm pointed rod. The specifications are given in IS 1199.
9. Modulus of rupture is calculated using the formula:
Explanation: The modulus of rupture is found out dividing maximum moment M/section factor Z. M is given by PL/6 and Z=1/6bd2.
10. A slump of 50-100mm can be used for:
a) Mass concreting
b) Strip footing
c) Trench fill
Explanation: Slump of higher value gives greater workability, but yields less strength. A slump of 25-75mm can be used for mass concreting and strip footing. A slump of 100-150cm is used for trench fill.
11. How many hoppers are there in compaction factor test?
Explanation: There are 2 hoppers and 1 cylinder in the apparatus. Concrete is poured in hopper A (first one). The hinged bottom is opened, concrete falls to 2nd hopper B. Again, hinged bottom is opened, concrete is allowed to fall into cylinder C.
12. If cylinder specimen is used to test compressive strength, equivalent cubes strength can be
a) 3/4th strength of cylinder
b) 5/4th strength of cylinder
c) 5/6th strength of cylinder
d) 1/4th strength of cylinder
Explanation: This formula is recommended by IS codes. IS 516 gives the details.
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