250+ TOP MCQs on Mix Design of LWC, Aerated Concrete and Answers

Concrete Technology Quiz on “Mix Design of LWC, Aerated Concrete”.

1. What is the amount of mixing water used to make LWC?
a) 1/2
b) 2/3
c) 1/4
d) 1/3
Answer: b
Clarification: The general practice for structural light-weight concrete is to mix the aggregate and about 2/3 of the mixing water for a period upto one minute prior to the addition of cement and the balance mixing water.

2. What is the normal time to get uniform mixing?
a) 30 seconds
b) 2 or more minutes
c) 1 minutes
d) 24 hours
Answer: b
Clarification: Mixing is done continuously as required for homogeneity. Usually, 2 or more minutes are required to get uniform mixing.

3. The strength of the resulting concrete is _______ % lower than when dry aggregate is used for the same content.
a) 5-10
b) 10-15
c) 15-20
d) 0-5
Answer: a
Clarification: It has been seen that the strength of the resulting concrete is about 5 to 10 percent lower than when dry aggregate is used for the same content and workability.

4. The density of concrete made with saturated aggregate is ___________
a) High
b) Low
c) Very high
d) Very low
Answer: a
Clarification: Moreover, the density of concrete made with saturated aggregate is higher and the durability of such concrete, especially its resistance to frost is lower.

5. The light-weight concrete is prepared by ________
a) Mixing Portland cement with sawdust in specified proportion in the concrete
b) Using coke-breeze, slag as aggregate in the concrete
c) Mixing Al in the concrete
d) Mixing Fe in the concrete
Answer: b
Clarification: The light-weight concrete is prepared by using coke-breeze, cinder or slag as aggregate in the concrete.

6. Aerated Concrete is _________
a) Very heavy weight
b) Heavy weight
c) Medium weight
d) Light weight
Answer: d
Clarification: Aerated concrete is also referred to as gas concrete, foam concrete, cellular concrete. In India we have at present a few factories manufacturing aerated concrete.

7. Air contents should be _________ % by volume.
a) 1-2
b) 2-3
c) 3-4
d) 4-5
Answer: c
Clarification: This type of cement was first of all developed in U.S.A. It is recommended that air contents should be 03-04 % by volume.

8. Which one is not used as air entraining agents?
a) Alumina
b) Natural resins
c) Fats
d) Oil
Answer: a
Clarification: Natural resins, fats, oils are used as air entraining agents not alumina.

9. Entrainment of air while applying cement, increases resistance to frost action.
a) True
b) False
Answer: a
Clarification: It is found that entrainment of air or gas bubbles while applying cement, increases resistance to frost action.

10. Aerated concrete is made in the density of approx. _________ kg/m³.
a) 50
b) 150
c) 250
d) 350
Answer: d
Clarification: Aerated concrete is made in the density range from 300 kg/m³ to about 800 kg/m³.

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