PASSIVE WIRELESS SENSOR SYSTEM FOR CONCRETE MATURITY MONITORING

Determination of strength in curing concrete is a crucial requirement for quality assurance in industrial construction projects. ASR&D is currently developing a wireless concrete maturity and post-cure thermal history monitoring system utilizing passive surface acoustic wave temperature sensors. These novel sensors use energy contained in an interrogating RF signal to activate the sensor, measure the temperature, and radiate a device identification and temperature measurement response back to the receiver. This response can be used to implement a well-known non-destructive method for determining the strength of curing concrete called the "Maturity Method". The embedded portion of the system consists solely of the SAW sensors with antennae, providing a small, rugged, low cost alternative to existing maturity monitoring systems. These devices require no batteries, can operate at extreme temperatures, and have almost unlimited lifetimes. Thus, these sensors can provide post-cure thermal history monitoring of the structure, data critical for thermal stress analysis. The system under development will provide structural engineers with a non-destructive method to automatically and cost-effectively monitor (in-situ) the thermal history and strength of curing concrete throughout a structure. This will allow construction to proceed as rapidly as possible while assuring safety through adequate quality assurance of the construction.