The IDEA product is a new nondestructive technology to evaluate the effectiveness of sealers applied to concrete bridge decks. The concept uses time-lapse thermography to measure water absorption/evaporation characteristics on a bridge deck in order to assess the effectiveness of concrete sealer. The new method is simple to implement and is built on an existing platform for time-lapse imaging of concrete that is used to detect and locate subsurface corrosion damage (e.g., delamination). The method consists of applying water to the surface of the deck and observing the evaporation of the water with time-lapse thermal imaging. Evaporation rates are determined based on the time-lapse thermal imaging and analyzed to determine if the sealer is preventing the absorption of water into the concrete. The project study included a review of current bridge deck sealing practices which provided examples of deck sealing policies and practices. The review showed that there are currently no methods for assessing the quality of sealer application in-situ or assessing the need for resealing a deck. Current assessment methods for sealers consist of indirect tests and offline methods performed on small cores or representative samples. As a result, resealing of decks is currently conducted based on policies for resealing that range from 3-10 years in different jurisdictions. The new technology for assessing the effectiveness of sealers, known as SealCheck, was developed through laboratory testing and verified in field tests. Tests were performed on small paver slabs to develop algorithms that examined the thermal signature of the evaporation process. The measurement method was validated on two in-service bridges in Missouri. The field tests included three separate scenarios; a partially sealed deck, an unsealed deck, and a sealed deck. The field tests demonstrated that the SealCheck technology could differentiate sealed concrete from unsealed concrete under field conditions. The characteristic V-shaped pattern identified in laboratory testing was reproduced in the field. It was found that the measurement period of the test took less than 1 hour to complete in the field. The project successfully demonstrated the ability to measure evaporation rates in the field on an in-service bridge, across a large area of deck surface, and correlate these measurements to the effectiveness of the sealer. Additional field-testing efforts will be required to better understand the full capabilities of the measurements and how they may best be used. This new test could be implemented in conjunction with deck condition assessment using the same infrared (IR) technology and field setup. In this way both the need for sealing (or resealing) of the deck and the need for localized patching to repair subsurface damage could be completed in a single test. This tool could provide critical data for effective preservation strategies to significantly increase the service life of a bridge deck. The SealCheck test could also be used to evaluate and develop performance specifications for sealer products, identify approved products, or assess new sealer products.
The final report is available.
