Concrete Maturity System

Engius developed the intelliRock Maturity logger in 2002. It won the 2003 World of Concrete award for innovation and has seen rapid growth and adoption on many major US projects in a short time. The reason? It is a simple and extremely cost effective device. Scancem Materials, known for their introduction of leading edge concrete technology has been appointed as the exclusive distributor.

The Concrete Maturity Method

The concrete maturity method is a proven strength estimation technique (ASTM C 1074) that accounts for the effects of time and temperature on the strength development of in-place concrete. This method gives a continuous estimate of concrete strength during the curing period and can be used to:

Accelerate construction & reduces formwork costs by allowing early stripping & stressing
Eliminate the need for expensive curing after formwork removal
Reduce the disruptive curing time on flat work by proving concrete has reached a self cure state (defined by strength)
Improve safety by giving a simple means of accurately gauging strength of critical elements before support removal (eg tilt up, suspended slabs)

Application involves:

the development of strength-maturity relationship
measuring the Maturity of insitu concrete to give an instant and accurate assessment of insitu strength.

Generating The Strength/Maturity Calibration Curve

Figure 1 - IntelliRock Reader and Logger

Figure 2 - Generating the Calibration Curve

The strength-maturity relationship is generated in the laboratory by first preparing cylindrical specimens made from the same mix-design that will be used in the field. Two specimens are instrumented, e.g. by intelliRock maturity loggers (figure 1), to record the time-temperature history and calculate the maturity while sets of 3 cylinders are typically crushed for strength at 1,2,4,7 and 14days (figure 2). Finally, a graph of maturity versus strength is generated (this can be done using the spreadsheet that comes with the intelliRock maturity reader).

Measuring Maturity and Strength in The Field

The time-temperature history of the concrete insitu is now recorded and integrated over time. Using intelliRock maturity loggers this is extremely simple as the temperature gauge, temperature/time logger and the maturity integration are all undertaken in a 35mm long x 30mm diameter cell that is embedded in the concrete. A wire is taken to the surface where the maturity reader can be plugged in at any time to download or simply read off the maturity and hence strength (figure 3).

Application for Maturity Monitoring

Figure 4 - Figure 4 - Maturity Across a Wall

Maturity monitoring gives insitu strength but that strength can be used to determine if the structure is "cooked" from a load or durability perspective. The key difference is that for load the strength of the bulk concrete is required and for durability the strength of the cover zone is required.

Loggers

*Logs temperature time only.
Temperature accuracy +/-1^oC
Nurse Saul & Arrhenius calculation
Operating temperature -18^oC to 85^oC
Battery last for 6-12mnths from turning logger on
Logs for period specified but data retained while batteries last. Weight 80gms