The age at which the concrete strength is to be tested must be entered on the mix design form.

The age at testing is significant, because the strength of a concrete specimen increases with time, if it is kept under the favorable conditions, which are specified for testing.

The age entered should match one of the ages for which expected strengths are given in the cement file, that is to be used for the mix. The ages in the standard cement files, which are provided by Firstmix, are 3, 7, 28 and 91 days.

If the age you enter on the mix design form does not match one of the ages in the cement file, Firstmix will use interpolation to obtain the expected concrete strength at the given age, increasing the likelihood that the mix will not provide the required target strength.

If Trial Mix results are used, the concrete strength is estimated from the test strength of the trial mix and the mix design will apply to the strength at the Trial Mix Concrete Age at Testing.

Range: 3 - 91 days.