How to Use Maturity Meters

Here’s a step-by-step guide for how to estimate concrete strength using the COMMAND Center iButton maturity sensor.

Step 1 - Build the Maturity Curve
A “Maturity Curve” is a graphical representation of the relationship between concrete strength and maturity. To build the curve, maturity sensors are inserted in concrete beams and columns using a mix that is as close as possible to the concrete to be used during construction. The maturity data is collected using your Pocket PC and fitted to a curve using either COMMAND Center’s desktop software version or another program like Microsoft Excel. Either way, there are a number of ways to plot the data whether it’s by using a logarithmic or hyperbolic function, a linear fit on a semi-log plot, or a more complex sigmoidal function. A curve-fitting technique is provided by most specifications.

It’s important in this step to batch and test concrete that will be as close as possible to the concrete used during construction. This includes batch size, mixing equipment, mix proportions, material sources and manufacturers. Any deviations in concrete preparation will reduce the quality of strength estimates from the maturity curve.


Step 2 - Estimate In-Place Strength
Once the maturity curve is built, COMMAND Center makes it simple to estimate the in-place concrete strength. The first step is to batch the same concrete (materials, proportions, mixing equipment, etc.) that was used to develop the maturity curve.

Routine QC/QA tests are then performed to ensure concrete is of the same quality and meets minimum specifications.

During construction, embed sensors to monitor the maturity development of the concrete structure. It’s important to make certain that proper delivery, consolidation and curing practices are followed to fulfill the assumptions of maturity theory.

Finally, use COMMAND Center’s measured maturity value and your maturity curve to estimate the in-place strength. Periodically and before performing safety-critical operations, the curve should be verified.

Step 3 - Verify the Maturity Curve
Since materials, mixing equipment performance, and construction conditions may vary over time, it is important to verify the strength-maturity relationship. The maturity curve should be verified periodically throughout the duration of a project, before performing safety-critical operations, and whenever any doubt about the curve exists. There are two methods to verify the maturity curve:

Verification of the maturity curve should be a component of the overall QC/QA plan for any project. This process ensures the relationship is current and viable. Many specifications will use this step to revise or recalculate the maturity curve.