1) What type of cement is preferable in sea
water construction?
Ans: Slag or Pozzolana (PSC or PPC) as per IS 456: 2000 Cl. 8.2.8.
2) What should be the pH of water used in concrete?
2) What should be the pH of water used in concrete?
Ans: As per IS 456: 2000 Cl. 5.4.2, pH
of water shall be not less than 6.
3) When the possibility of Segregation of concrete is more?
3) When the possibility of Segregation of concrete is more?
Ans: a) When water cement ratio is
high
b) If
the ratio of coarse aggregate is much more than the other proportion
c) Coarser grading.
4) Which Code we use for Concrete Mix Design?
Ans: IS 10262: 2009.
5) What is the weight of Cube of Size 150 mm x 150 mm x 150 mm?
5) What is the weight of Cube of Size 150 mm x 150 mm x 150 mm?
Ans: 8.1 Kg.
6) What are the meanings of 43 grade, 53 grade on Cement bags?
6) What are the meanings of 43 grade, 53 grade on Cement bags?
Ans: Cement grade indicates the
Compression strength of cement after 28 days of setting.
7) Which Zone Sand is suitable
for Plaster?
Ans: Zone – 3.
8) Which Zone sand is suitable for Filling purpose?
8) Which Zone sand is suitable for Filling purpose?
Ans: Zone – 4.
9) Which Zone sand is suitable for Concrete?
9) Which Zone sand is suitable for Concrete?
Ans: Zone – 2.
10) What percentage of water we can
increase for every 25 mm slump?
Ans: As per IS 10262: 2009 Cl. 4.2, we can increase 3% for
every additional 25 mm slump.
11) What is the full form of A.A.C Block?
11) What is the full form of A.A.C Block?
Ans: Autoclaved Aerated Concrete.
12) What is the meaning of M50?
Ans: Here ‘M’ stands for ‘Mix’. 50 stands for Characteristics compressive
strength of concrete cube size 150 mm x 150 mm x 150 mm, after 28 days curing.
Its unit is N/mm2.
13) What is the size of mould
used to measure the compressive strength of Cement?
Ans: As per IS 10080: 1982, the size of mould is 70.6 mm x 70.6 mm 70.6 mm.
14) What is the percentage
strength of concrete with time?
Ans: After 1 day – 16%, After 3 days – 40%, After 7 days – 65%, After 14
days – 90%, After 28 days – 99%.
15) What maximum height permissible
for free fall of concrete?
Ans: As per IS 456:2000
Clause – 13.2, It is 1.5 m.
16) What are the factors
affecting strength of concrete?
Ans: Quality of Raw Materials, Water – Cement Ratio, Coarse – Fine aggregate
ratio, Aggregate – Cement ratio, Curing period, Temperature, Compaction of
concrete.
17) What do you
mean by Segregation?
Ans: Segregation is a separation
of cement, sand from aggregate.
This is caused due to Water
cement ratio and when
concrete is poured about
more than 1.5m.
18) What is the Initial and Final setting time of cement?
18) What is the Initial and Final setting time of cement?
Ans: Initial – 30 mins ; Final – 10
hours.
19) What do you mean by honeycomb in concrete?
19) What do you mean by honeycomb in concrete?
Ans: Honeycomb, also known as
air pocket, is nothing but
the air voids in
concrete. It is usually formed during concrete casting.
20) Does Water
damage concrete?
Ans: Plain concrete is not affected
or damaged by water but
Reinforced Concrete (R.C.C)
can be damaged due to
water. This is because the
water may seep into the
concrete and corrode the
steel reinforcement inside.