**Compressive Strength**The strength recorded from compression tests.

**Curing time**The time from concrete placement.

**Early-Age Strength**

The strength within the first few hours or days after casting concrete.

**Equivalent Age**

The number of hours at a specified temperature required to produce a maturity equal to the maturity achieved by a curing period at temperatures different from the specified temperature. (1)

**Final Strength**

The required strength after 28 days.

**In-Place Strength**

The estimated strength of the field concrete.

**Maturity**

The extent of the development of a property of a cementitious mixture. (1)

**Maturity Curve**

A curve presenting the strength-maturity relationship to be used for estimating the strength of the concrete mixture cured under other temperature conditions. (1)

**Maturity Function**

A mathematical expression that uses the measured temperature history of a cementitious mixture during the curing period to calculate an index that is indicative of the maturity at the end of that period. (1)

**Maturity Index**

An indicator of maturity that is calculated from the temperature history of the cementitious mixture by using a maturity function. (1)

**Maturity Instrument**

Device that records the concrete temperature as a function of time and compute the maturity index.

**Maturity Method**

A technique for estimating concrete strength that is based on the assumption that samples of a given concrete mixture attain equal strengths if they attain equal values of the maturity index. (1)

**Strength-Maturity Relationship**

An empirical relationship between compressive strength and maturity index that is obtained by testing specimens whose temperature history up to the time of the test has been recorded. (1)

**Target Strength**

The required strength before demolding.

**Test age**

The time from concrete placement until compression test.

(1) ASTM C1074 - Standard Practice for Estimating Concrete Strength by the Maturity Method

(2) Concrete in Practice 39 - Maturity Methods to Estimate Concrete Strength