Maturity calibration
To estimate the concrete strength using the maturity method, you need to make a maturity calibration.
The aim of performing a maturity calibration is to find the relationship between time, temperature, and strength for each concrete mix design that you intend to use. This relationship is called the strength-maturity relationship and is established in a laboratory.
Once you have found the strength-maturity relationship for your specific concrete mix, you can use this to estimate the in-place strength of the concrete at your job site.
Table of Contents
Calibration procedure
The procedure for making a proper maturity calibration is well described in the ASTM C1074 standard practice. We recommend you to read this and become familiar with all the details on how to make a successful calibration.
Required equipment
- Temperature sensors to measure temperature.
- Data loggers or transmitters to record the temperature.
- Equipment for making and curing test samples.
- Compression testing machine.
How to perform a maturity calibration
1. Prepare the samples
Prepare at least 15 samples so that you are able to perform tests at minimum five different test ages. Three samples are needed for each test age, two for the actual tests and the third in case the difference between the two first test results is higher than 10% from their average.
The samples must be prepared according to standard procedures for making and curing concrete test samples in the laboratory or in the field.
2. Embed temperature sensors
Embed temperature sensors in at least two of the samples. The sensors must be placed within ±15 mm of the center.
3. Connect data loggers or transmitters
Connect a data logger or transmitter to the temperature sensors as soon as possible. These will record the temperature history, which will be used to calculate the maturity.
4. Cure the samples
Once the samples have been prepared, cure all of them according to standard procedures and under the same conditions, e.g. in a water bath or moist room.
It is important to have the same curing conditions for all the samples in order to obtain a correct correlation between the strength and maturity.
5. Perform compression tests
For the first test age, break two samples and note down the compressive strength for each of them. Also note down the date and time. Finally, calculate the average strength for the samples.
- If the difference between the two tests is higher than 10% from their average, break the third sample and use the average of the three.
- The samples with the temperature sensors embedded should be tested last to remain for maturity monitoring.
6. Determine the maturity
Find the related maturity value at the time of the compression tests. When you have determined the maturity for each of the instrumented samples, calculate the average maturity of these.
- Using data loggers? You will need to manually calculate the maturity using one of the maturity functions.
- Using Maturix? The maturity will be calculated automatically and you can read it directly from the graph.
7. Determine the strength-maturity relationship
You have now determined the strength-maturity relationship for your first test age. This consists of:
- The average compressive strength found through the break testing
- The average maturity found by calculating the maturity from the temperature history up until the time of the test
Now find the strength-maturity relationship for the remaining test ages by repeating the last three steps above.
Test age | Maturity (days at 20 °C) | Strength (MPa) |
|---|---|---|
1 | 1 | 10 |
2 | ||
3 | ||
4 | ||
5 |
Once you are finished with all the test ages, gather the results in a table. Each test age shows the correlation between the average compressive strength and the average maturity.
Test age | Maturity (days at 20 °C) | Strength (MPa) |
|---|---|---|
1 | 1 | 10 |
2 | 3 | 18 |
3 | 7 | 23 |
4 | 14 | 26 |
5 | 28 | 30 |
8. Create the maturity curve
Plot the maturity vs. strength for each test age and create the best fitting curve.
You can now use the maturity calibration to estimate the in-place strength of the concrete at your job site.
Read our Estimate In-field Concrete Strength with the Maturity Method article to learn more.
Further reading
If you want to see a step-by-step explanation about how to make a maturity calibration using Maturix:
If you use Maturix In-Situ:
If you use Maturix In-Situ:
