Question

Problem 3:
The strength of a concrete is measured as 3200 psi after 10 days. Knowing nothing else about the
concrete, what would you expect the 28 day strength to be?

Answer 1

Compressive strength gained by the concrete according to researches done for 28 days are mentioned below :

AGE	STRENGTH GAINED
1 DAY	16%
3 DAYS	40%
7 DAYS	65%
10 DAYS	75%
14 DAYS	90%
28 DAYS	99%

According to the data given to us the Strength of Concrete given to us is 3200psi after 10 days which means it has gain 75% strength of its total strength . And it is going to gain its remaining 24% strength in remaining 18 days that would be  . which is equal to 1778 psi .

So the total strength of concrete after 28 days would be 3200 + 1778 psi = 4978 psi

THANKYOU FOR PROVIDING ME THIS OPPORTUNITY :)