This set of Concrete Technology Quiz focuses on “Mix Design of LWC, Aerated Concrete”.
1. What is the amount of mixing water used to make LWC?
Explanation: 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
Explanation: 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.
Explanation: 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 ___________
c) Very high
d) Very low
Explanation: 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
Explanation: 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
Explanation: 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.
Explanation: 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?
b) Natural resins
Explanation: Natural resins, fats, oils are used as air entraining agents not alumina.
9. Entrainment of air while applying cement, increases resistance to frost action.
Explanation: 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.
Explanation: Aerated concrete is made in the density range from 300 kg/m3 to about 800 kg/m3.
Sanfoundry Global Education & Learning Series – Concrete Technology.
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