How To Use Command Center For Maturity To Estimate Concrete Strength
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. Use a compatible COMMAND Center™ reader to collect the sensor data and COMMAND Center™ software will guide you through generating a curve by automatically correlating the maturity data to your test specimen breaks. There are a number of ways to plot the data and COMMAND Center™ allows you to use multiple curve-fitting techniques. Most specifications provide a curve-fitting technique.
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.
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.
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:
- Monitor the maturity of strength specimens cast during construction and compare these strengths to the maturity curve
OR - Estimate the 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.
