Strength of cement and concrete with age

The strength of cement decreases as the age passes. In other words, the strength of cement is very low in comparison to that on the production day.  The following table shows how the strength of cement decreases with the passage of time.

Period of storage of cement (month)	Approx. relative strength at (28 days percent)
0	100
3	80
6	70
12	60
24	50

In view of the above, it is always advised to use only fresh cement i.e. the cement produced within 1 or 2 months. Also never buy cement in large quantities. Instead, buy cement at regular interval of time depending upon the quantity which can be exhausted within 1 or 2 week.

But in the case of concrete, the strength increases with the passage of time, of course proper Curing has to be done for the stipulated period i.e. at least for 7 days. The following table shows the strength of concrete with respect to its age.

Age of concrete	Approx. Strength (percent)
1 day	16
3 days	40
7 days	67
28 days	100
3 months	122
6 months	146
12 months	155