Approximate percentage strengths of concrete with age.

Approximate percentages of strength of ordinary portland cement concrete at different ages in comparison with the strength at 28 days.

Age:                       Strength (percent)

01 day.                          16

03 days.                        40

07 days.                        67

28 days.                       100

03 months.                  122 

06 months.                  144

12 months.                  155