Engineers have used maturity calculations to help contractors complete jobs faster since the late 1980s. If they can know when a placement will achieve minimum strength without conducting time-consuming break tests on field-cured cylinders, contractors can strip forms, post-tension, remove shoring, end cold-weather protection, and move on to the next step that much sooner.
A plethora of companies offer solutions for gathering and sharing temperature data used to predict set time and strength. The first solutions were external: A sensor at the end of a wire buried in concrete attached to a processing unit outside the placement and someone came along at various intervals to note the readings. Then came sensors that gather and read data but still require connecting to a processing unit to download data. The smartphone ushered in the latest era: sensors with wireless transmitters that gather and send data through the concrete into the phone via Bluetooth or cellular connection and an app uploads it to a cloud-based website where anyone authorized to access the data can view it.
The numerous case studies promoting these solutions emphasize how much time the contractor saved. However, they often fail to mention that maturity curves must be developed for each mix before placement to ensure readings reflect what’s going to happen in the field – a time-consuming process in and of itself. And until the industry fully adopts the maturity method, owners and contractors are still going to conduct break tests for peace of mind or compliance with contract documents.