Concrete Maturity represents the combination of time and temperature. It is calculated based on the temperature history of the structure by applying one of the maturity functions. In its essence, maturity is:
Maturity = time * temperature
The main concept about concrete maturity is that a specific value of maturity can be obtained with many different combinations of time and temperature. For example, the graphs below represent the temperature history of three different pieces of concrete. All of these have reached the same maturity of 100 °C-hours, but it took a different amount of hours to do so. This is because the temperature has been different throughout that period.
If you look at the first graph (Graph 1), you will see that the temperature is 20 °C and that it has been curing for 5 hours. This gives a maturity of 100 °C-hours.
If we compare this with Graph 2, you will see that the temperature is higher. Since the concrete temperature has been at 40 °C, it only took 2,5 hours for it to reach the same maturity of 100 °C-hours.
Looking at Graph 3, the temperature is the lowest of the examples at 10 °C, and in this case it will take 10 hours to reach the maturity of 100 °C-hours.
Concrete maturity alone does not indicate how strong the concrete is. However, by using the maturity method, you can determine the relationship between maturity and strength development.
The maturity method is an easy way to estimate the early-age strength development of a concrete mix. The main assumption of the maturity method is that if two samples of the same concrete mix have the same maturity, then they will also have the same strength – even if they were cured under different temperature conditions.
To use the maturity method you will need to perform a maturity calibration, which includes doing tests in a laboratory to find the relationship between the concrete maturity and the concrete’s strength. Once you know this relationship, you can estimate the strength of the in-place concrete by placing temperature sensors in the structure. You can find the maturity by looking at the temperature history measured by the temperature sensors, and then determine the in-place strength using the maturity calibration.