The Maturity Curve

A maturity curve is a graphical representation of the relationship between concrete strength and maturity.

Construction teams use the maturity curve of a specific concrete mix to estimate the strength of in-place concrete. Below, you’ll find general information about the concrete maturity curve. This information is a simple introduction—before beginning any maturity project, the details of maturity must be studied in greater detail.

Creating a Maturity Curve

Since the maturity curve is simply a graph of concrete’s strength-maturity relationship, you’ll need to calculate the relationship between strength and maturity for your particular concrete mix.

To calculate the relationship, conduct lab tests:

  1. Cure concrete test specimens in a lab while tracking their maturity with embedded sensors.
  2. Conduct compressive or flexural strength tests at standard time intervals on identical test specimens.
  3. Determine the relationship between the test specimens’ maturity and strength.

To create the maturity curve, choose from a number of curve-fitting techniques. ASTM C1074 does not specify a particular curve-fitting technique for maturity curves. COMMAND Center allows the user to choose between a logarithmic, natural log, or hyperbolic equation to calculate a best-fit curve through their maturity data.

Tips for a Successful Project

It’s important to batch and test concrete that is 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 may reduce the accuracy of strength estimates derived from the resulting maturity curve.

Since materials, mixing equipment performance, and construction conditions may vary over time, it’s 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:

  1. Monitor the maturity of test specimens cast during construction and compare the maturity-estimated strength of these specimens to the actual compressive or flexural strength test results of companion specimens.
  2. Estimate the concrete’s in-place strength using other methods, such as Windsor Probes or Pull-Out Tests.

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.

When using the maturity method, construction teams can estimate real-time strength gain of in-place concrete on the job site. There’s no need to waste valuable construction time waiting for the strength of standard test specimens to catch up to the in-place concrete.

Without maturity monitoring, in-place concrete strength is estimated by performing compressive cylinder tests in a laboratory. Relying solely on lab tests requires several specimens and can waste valuable time if a project’s in-place concrete reaches sufficient strength before standard test intervals. In the construction business, time is money.

To save time and money on a project, the construction team monitors maturity to quickly determine when concrete has reached its required strength.

Sensors in cylinders

Key Maturity Benefits

  • Concrete strength can be evaluated in real-time.
  • Less time is spent waiting for test specimens to catch up to concrete strength.
  • The number of test specimens required for QC and potentially QA will decrease.
  • Tendons may be stressed, forms and shores may be stripped and removed, and loads may be applied sooner than otherwise anticipated.
  • Expedited schedules may result in bonuses.
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