Determining Concrete Maturity with Temperature Monitoring

CLEVELAND - Feb. 24, 2022 - PRLog -- Thermocouple Data Loggers Save Time & Improve Safety

Concrete maturity is a measure of how much a batch of freshly poured concrete has cured and is a quick indicator of the in-place strength at that time relative to when it is fully cured. Traditional measurements of concrete strength rely on lab tests of field cured sample cylinders of concrete made in parallel with the main pour or pullout or penetration tests made on site. The concrete maturity method calculates an index based on time vs. temperature data and then using the strength-maturity relationship one can determine a good estimate of the strength at that point in time.

What is the Concrete Maturity Index?

The maturity method is based on the idea that the strength of concrete is based on the hydration of cement in the mix. This hydration is an exothermic reaction that gives off heat. By recording the temperature profile at regular time intervals during the curing process, you can estimate the maturity and from this, the estimated strength of the concrete on-site and in real-time without having to send samples to a lab for more traditional tests.

How to Measure the Concrete Maturity Index

The use of the maturity method in real applications requires 3 pieces. First, temperature sensors need to be embedded in the pour. The simplest way to accomplish this is to obtain a spool of thermocouple wire, commonly 20 to 24 gauge solid K or T type wire. The actual sensor is created by stripping a short length of wire, approximately 1/2", and then twisting the two conductors together. The sensor is placed in a convenient location in the pour, either before or immediately afterward. It's important that the sensor is in good physical contact with the concrete. The thermocouple wire is extended out to a spot where the data logger can be placed out of harm's way.

For the data logger, a simple battery-powered stand-alone unit like the Grant Squirrel OQ610 or VersaLog VL-TC allows temperature data for multiple locations to record.

Conclusion

The Maturity Index provides a convenient way to estimate the in-place strength of concrete during curing. It is based on the principle that the strength is can be determined based on the temperature-time history during the curing process. Using a thermocouple data logger with simple thermocouple temperature sensors embedded in the concrete allows the data to be recorded. This data can then be quickly analyzed using a tool like Excel to calculate the maturity index.

For more information on concrete temperature monitoring, or to find the ideal solution for your specific needs, contact a CAS Data Logger Applications Specialist at (800) 956-4437 or visit us at https://www.dataloggerinc.com.