Companies have typically used temperature loggers with wires from the device running into the concrete, since concrete gives off heat as it cures. But wired sensors can be too cumbersome for large projects, so in such scenarios, a concrete consultant often sets a conservative estimated curing timeline based on the material being used, as well as other conditions. This often means extra time is built into a project's timeline, in order to ensure that all concrete poured is fully cured before employees proceed to the next step.
Shimmick Construction Co. preferred not to use wired sensors or build in extra curing time for the construction of San Francisco's new TransBay Transit Center, so the company chose to deploy an RFID solution provided by Michigan technology company Wake, Inc. The system, installed when the TransBay Transit Center project launched approximately two years ago, consists of active ultrahigh-frequency (UHF) RFID tags with built-in sensors, as well as handheld readers and software to interpret the collected temperature data. The tags' sensor probes are embedded in each concrete slab and the data is read remotely, making the system more nimble than conventional data loggers.
Shimmick is laying 100,000 cubic yards of concrete to build a below-grade substructure for the new San Francisco transit facility. Next, the company intends to utilize the same Wake Inc. technology—the Wireless Concrete Maturity & Temperature Monitoring Solution, also known as HardTrack—during the building of concrete pilings for a bridge associated with that project.
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