When needing assistance to address a moisture problem with their concrete temperature sensors, Pile Dynamics, Inc. (PDI), a Solon company, turned to NASA’s Glenn Research Center engineers in Cleveland to help solve it. As a result, thermal sensors that incorporate NASA’s contribution will be placed inside sixteen 150 feet-deep drilled shafts that will support the Eastbound George V. Voinovich Bridge, being built in downtown Cleveland.
The collaboration was a result of the Adopt-a-City program that matched small and mid-size manufacturers with experts from Glenn to help companies solve challenges they were experiencing with a new or existing product. In 2012, PDI was selected into the program to receive up to 40 hours of pro bono assistance from Glenn experts.
PDI, a Solon company that provides quality assurance systems for the deep foundations industry, came to Glenn to work with their materials researchers to investigate low cost, watertight materials that rendered the sensors resistant to the wet concrete environment in which they function. Sandi Miller, a Glenn materials expert, performed experiments that explained the important properties of adhesives used in the manufacturing process and why they worked. She also suggested alternatives that would improve bonding to provide a waterproof seal.
Paul Bartolotta, one of the coordinators of the Adopt-a-City effort and an aerospace engineer at Glenn, added, “NASA experts validated the Pile Dynamics encapsulation process to ensure moisture did not harm their sensors. The validation process included a detailed microstructural analysis of the encapsulated sensors utilizing NASA’s powerful electron microscopes.”
“It was great having the expertise and technology available from NASA help us with product development. Pile Dynamics has added a number of employees just to manufacture our new product and we are happy with the great acceptance it gained in the industry,” said Dean Cotton, senior engineer at PDI.
The thermal sensors are encapsulated at regular intervals along the length of Thermal Wire® cables manufactured at the PDI Solon facility. The cables are used in Thermal Integrity Profiling, a methodology of assessing the integrity and shape of cast in place concrete foundation for which the American Society of Testing and Materials (ASTM) will issue standard requirements in the next few weeks.
To obtain the temperature measurements necessary for the assessment, the cables are installed in cast-in-place foundations prior to concrete being poured. As soon as the concrete pour is complete, the sensors start measuring temperatures. A day or two after, there may already be sufficient data for an engineer to approve the shaft, allowing construction to continue. This time frame is much shorter than other concrete integrity tests.
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