We’ve answered the questions about COMMAND Center and concrete temperature and maturity monitoring we hear most often.
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Maturity’s advantages can far outweigh the costs associated with it. Adding maturity to traditional testing can increase safety, expedite construction schedules, and improve construction methods.
Maturity monitoring is implemented to verify standard testing and to estimate in-place concrete strength in real-time strength at the job-site. The advantage: calculate strength at the job site instead of waiting for standard testing intervals, and increase quality control and assurance with strength verification.
Once standard strength tests have been completed, the maturity method uses that test data to calculate a strength-maturity relationship and a maturity curve for the specific concrete mix. This mathematical relationship allows you to use maturity as an indicator of your in-place concrete’s strength. Simply track your concrete’s maturity by placing sensors in your concrete at the job site—then read the sensor at any time to receive an estimate of your concrete’s strength based on the established strength-maturity relationship for that mix.
Even when the maturity method is being implemented on a project, concrete samples are also tested throughout construction in order to validate the maturity curve.
To learn more about the specific tests that will be conducted during construction on a project using COMMAND Center maturity monitoring, visit our Monitor Concrete Maturity and Strength page.
You’ll conduct two rounds of strength tests (compression or flexural) on concrete specimens in a lab: in the first round, you’ll use the data to develop your concrete mix’s maturity curve. In the second round, you’ll use the data to verify your concrete mix’s maturity curve while your in-place concrete is curing on the job site.
Your first strength tests allow you to develop a calibrated maturity curve that graphs the relationship between temperature, time, and strength for your project’s concrete mix design. If you will use multiple mix designs on a project, you will conduct tests and develop a maturity curve for each mix. Each maturity curve is specific to each mix’s unique combination of materials and proportions.
Testing should follow standard methods such as ASTM International C 1074: Standard Practice for Estimating Concrete Strength by the Maturity Method. In summary, ASTM C 1074 works like this:
- A trial batch of the desired concrete mix design that will be used in the structure, pavement, or slab is prepared.
- The mix is poured into a series of test specimens (cylinders or beams).
- Temperature-monitoring sensors are inserted into two of these specimens.
- The specimens are all cured in the same manner, typically in a water bath or moist room.
- While curing, the temperature sensors are read and maturity data is calculated by software.
- Specimens that do not contain the sensors are periodically broken and tested for strength at ages of interest.
- A relationship between maturity and strength is established, and together this data is used to estimate the strength of the field concrete.
These laboratory tests are conducted prior to construction. You’ll develop your concrete mix’s calibrated strength-maturity curve in the lab, and then you’ll use that relationship to evaluate your in-place concrete at the job site.
Subsequent strength tests take place during construction and allow you to verify your concrete mix’s maturity curve. This testing is part of regular concrete construction: specifications for quality control and acceptance on any concrete project require you to cast concrete specimens and conduct compression strength tests at regular intervals during construction. When using maturity, you’ll add one extra step to this standard procedure: embed a sensor into one of the specimens to monitor its temperature over time. Evaluate your maturity curve by comparing the specimen’s maturity data with strength data from your strength tests. If a specimen breaks within a 10% deviation of the strength predicted by the maturity data, the curve has been verified.
Using the maturity method is not a replacement for traditional testing methods, but it can reduce the number of extra cylinders cast for traditional tests. Most specifications require construction teams to cast specimens in the field, cure them in ideal conditions, and then conduct compression strength tests at specific time intervals. Construction teams will commonly cast extra specimens for these tests because often several specimens must be discarded due to unexpectedly low strengths. Maturity decreases the chance of these discards—if a temperature sensor is embedded in the specimen, construction teams can determine its strength by reading the sensor data and determining strength from the maturity curve instead. This prevents construction teams from conducting a strength test on a specimen before enough strength is gained. By preventing discarded specimens, they can reduce the number of extra specimens needed for testing.
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