Dr. Marc Maguire’s project titled “Performance of High Early-Strength Materials Used in Concrete Bridge Repair” studied the performance of high early-strength (HES) materials used in concrete bridge repair by looking at past patch repair projects. The project included site visits to 24 bridges in 3 Nebraska districts to depict the field performance of these materials. Surveys were also sent out to surrounding states to get an idea of their standard practices.
After surveying 10 other states, it was found approximately 90% of them reported using HES materials, and 65% have been using them for more than 10 years. Only three of the states use NTPEPs to approve their materials, where the rest rely on internal testing, product datasheets, and manufacturer testing data. Only 50% of the states have an approved product list for HES materials. The four most common materials used were Portland cement, polymer concrete, magnesium phosphate and sulfoaluminate repair materials in descending order.
This project was funded by the Nebraska Department of Transportation (NDOT) and looked at HES materials specifically on their approved product list. The mechanical and durability properties of all 60 HES repair materials listed on the NDOT-approved product list were collected and organized into a spreadsheet available for use by NDOT staff. The experimental data previously provided for the list was either based on the product datasheet or the National Transportation Product Evaluation Program (NTPEP), but there was little knowledge on how the materials performed during actual repairs on Nebraska bridges.
Field inspections for the site visits were performed in the summer and fall of 2022. Researchers visited each site to collect photos and approximate the number of cracks and crack length. The repairs were then evaluated on a scale of 0 to 5 using a condition rating system introduced by a Minnesota Department of Transportation study performed by Burnham, Johnson and Worel in 2016.
In the study’s conclusion, it was found there was a significant difference in the experimental data from the NTPEP database and from the product datasheet. Researchers recommended HES materials used for bridge maintenance should be restricted to those tested and included in the NTPEP database due to the discrepancies in the manufacturer-reported values. Knowledge of HES material performance would benefit from the development of an extensive database for HES repairs done within NDOT, and a program could be made to monitor new repairs over time and track their performance.
Dr. Marc Maguire is an Associate Professor in the Durham School of Architectural Engineering & Construction at the University of Nebraska-Lincoln. His research interests focus on structural mechanics, probabilistic methods and reliability of structures, accelerated bridge construction, and structural health monitoring, non-destructive evaluation and inspection. In addition to NDOT, this research is also supported by the US Department of Transportation Federal Highway Administration.
