WHY DO WE CHOOSE 7, 14 AND 28 DAYS FOR CONCRETE OR COMPRESSION TESTS? -lceted LCETED INSTITUTE FOR CIVIL ENGINEERS

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Jan 13, 2021

WHY DO WE CHOOSE 7, 14 AND 28 DAYS FOR CONCRETE OR COMPRESSION TESTS?

WHY DO WE TEST CONCRETE AT 7TH,14TH & 28TH  DAY?

The maximum strength of concrete gains at 28th day. Because of the high capital risk in the construction industry, instead of testing the strength in 28th day, the strength can be checked in 7th and 14th day based on the concrete strength psi to predict the construction works target strength.


From the table below it is clear that in 24 hours concrete gains its 16% of strength, while concrete gains 65% of the target strength within 7 days of it's pouring.

WHY DO WE CHOOSE 7, 14 AND 28 DAYS FOR CONCRETE











Up to 14th day the concrete shows 90% of the target strength, after which the strength gain decreases, and it takes 28 days to reach 99% strength.


Strength of concrete cannot be determined until the concrete is stable. Also we will not wait 28 days to determine whether the concrete is suitable for construction or not, it kept it uniform, so the concrete is tested at various intervals.


The spike of maximum strength gain is seen for the first 14 days, so we test the concrete at intervals of 7th,10th & 14th day and if the concrete fails to show results of 90% of its overall strength  at 14th days then that batching is discarded.


Now, we think you know why do we test concrete for 7th ,14th  & 28th day?


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