The maturity method is used for estimating the in-place strength of concrete from the in-place maturity index and already determined laboratory data about the strength-maturity relationship of the specific concrete mix.

The maturity method assumes that samples of a given concrete mix will have equal strength values if they have equal values of the maturity index. To compute the maturity index, a maturity function is used.

### Maturity Functions

The most common standard practice is the ASTM C1074 – “Standard Practice for Estimating Concrete Strength by the Maturity Method”. This standard presents two alternative maturity functions for computing the maturity index from the measured temperature history of the concrete:

- The Nurse-Saul function
- This function is based on the assumption that the rate of strength development is a linear function of temperature, which is used to compute the temperature-time factor

- The Freiesleben Hansen & Pedersen function (based on the Arrhenius equation)
- This function is based on the assumption that the rate of strength development is a exponential function of temperature, which is used to compute the equivalent age at a reference temperature

### Procedures

The maturity method consist of two overall steps:

- Determining the strength-maturity relationship of the concrete mix (laboratory testing)
- Measuring the in-place maturity index and estimating the in-place strength (field measurement)

The first step needs to be determined prior to monitoring. The last step is done automatically by Maturix.