An expressway in Singapore is expected to be the first large-scale installation of a new concrete monitoring system that uses embedded, multisensor instruments from a U.S. company to analyze conditions in corrosion prone or structurally critical areas.

(Photo courtesy of Virginia Technology Inc.)

"Our first production units will be on the Kallang/Paya Lebar Expressway," says Bob Ross, president of Virginia Technologies Inc., Lynchburg, Va. The company has delivered the first 12 of 96 of the $1,000 monitors for the $1.8-billion, 12-km project.

The sensors are placed at the rebar level in the deck. Instruments have an on-board processor to convert readings to digital data before sending it by cable to logging devices, which can be as far as 200 ft away.

Ross says converting the data from analog to digital limits corruption from electromagnetic interference. The loggers can pass data on to a central station automatically by cell phone.

Sensors monitor internal temperature, as well as four electrical and chemical parameters from which unseen deterioration can be calculated.