Determining Concrete Maturity
Mini Concrete Maturity Meters
Grant Instruments distributor CAS DataLoggers has provided the temperature monitoring devices for a construction contractor which needed to monitor and record the cure of structural concrete onsite. Once workers could prove that the concrete was strong enough, they could then proceed with new construction. The company was on a tight work schedule, so they wanted to assemble all the necessary equipment and get setup as quickly as possible.
CAS DataLoggers supplied 3 Grant Mini Concrete Maturity Meters to log the concrete temperature at different points. The customer also opted for 100m rolls of temperature measurement cable with separate sub-miniature thermocouple plugs for the individual sensors. Each data logger was then connected to 2 Type K Thermocouples also provided by CAS DataLoggers.
Each Grant data logger is a compact unit supplied in a heavy duty, bright yellow waterproof case. Users install the dataloggers adjacent to a freshly-poured foundation and start logging. These small and versatile units are designed for data logging in concrete curing applications and are also suited for measuring surface and air temperature. Each data logger’s 2 temperature channels can be used for connection with several other thermocouple types.
These temperature data loggers monitor a wide temperature range from -40 to +90°C (-40 to 194°F). In order to determine concrete maturity, the sacrificial temperature measurement cables are cast into the concrete and cut off at the surface when the concrete has cured. In this way users collect all the necessary set temperature referential points.
Palm-sized at 50mm x 30mm, the portable data loggers are compact for easy placement, so onsite installation is easy. Safe inside their cases and designed with POM enclosures for low water absorption, the temperature recorders keep logging outdoors through the cold and rainy weather. Users can log up to 100,000 readings with each datalogger, choosing a sampling interval of one reading every minute.
Each data logger came delivered with a USB cable, lithium battery, optional calibration certificate, and free software. The battery has a life of about 4 years (sampling at 1 min/230 days).
The Mini-Meters are then connected directly to an office PC or laptop via their USB interfaces for fast data download. The data loggers included basic software which handles logger configuration, data downloading and data export. The Grant recorders work with users’ PCs running Windows 7. Using the supplied Microsoft Excel™ templates, users calculate the Concrete Maturity from elapsed time versus temperature, which is quoted as a “Maturity number.” They then use this Maturity number to determine when the concrete has cured sufficiently for formwork to be removed.