Curing of Concrete

Q. Relative humidity is :

1. The relative mass of water vapour per unit volume of space
2. The mass of water vapour per unit mass of moist air
3. The percentage ratio of the amount of moisture in a given space to the amount which that volume could contain if it were saturated
4. The humidity at which air becomes saturated cooled under constant pressure and with constant water vapour content

Q. The primary purpose of curing is to

1. Reduce the heat loss of concrete that is freshly placed to the atmosphere
2. Reduce the temperature gradient across the cross-section of the concrete
3. Both (a) and (b)
4. Neither (a) nor (b)

Q. For concrete exposed to dry conditions, the minimum curing period is:

1. 5 days
2. 7 days
3. 10 days
4. 14 days

Q. In normal circumstances where ambient temperature does not fall below ${15}^{\circ }$C, for a properly cured reinforced concrete slabs spanning up to $4.5$ metre span cast using ordinary portland cement, the props provided can be removed only after a minimum period of

1. $3$ days
2. $7$ days
3. $14$ days
4. $21$ days

Q. According to Indian Standard specifications, the concrete should be cured under a humidity of:

1. $30$
2. $50$
3. $60$
4. $90$