The maturity method is an approach utilized to predict concrete's strength in-situ based on its internal temperate. It is based on the fact that concrete gains strength faster when cured at higher temperatures and will gain little or no strength when exposed to very cold temperatures. The method considers these conditions in the field by recording the internal temperature of the concrete with special sensors.
At first, typical maturity tests were conducted by implementing sensors into the concrete and analyzing information using a data logger. However, nowadays, data can be obtained and analyzed using Bluetooth wireless technology. Two types of transmitters to perform Bluetooth maturity tests are available: The embedded transmitter and the transmitter that is placed outside of concrete.
Transmitter embedded within concrete
The Bluetooth transmitter is buried into the concrete and transmits data, which is obtained through a sensor that is placed further into the concrete. Using embedded transmitters, no wires extend out of the concrete. However, this approach is more expensive as the high-cost sensors are sacrificed. Moreover, the signal of the Bluetooth deteriorates when the transmitter is placed into a dense material and therefore data transmission becomes less effective. Last but not least, if the buried transmitter or the sensor is damaged there is no way to retrieve the data.
Transmitter placed outside of poured concrete
A non-embedded transmitter is placed outside of the concrete. The limitation of such transmitters is that wires extend from the concrete. Nevertheless, those devices are cost-effective as they can be utilized several times. More than one sensor can be linked to one transmitter, thus, an entire project can be executed using few or just one transmitter. Moreover, the signal does not have to pass through concrete so the optimal range can be achieved. Finally, in case that the transmitter is damaged, it can be swapped with a new device, without losing data.