Extending the Service-Life of Bridges using Sustainable and Resilient Abutment Systems: An Experimental Approach to Electrochemical Characterization of Lightweight Mechanically Stabilized Earth

The corrosion of metallic materials, such as steel bars, inside mechanically stabilized earth (MSE) walls is the primary concern that limits their designed service life and increases maintenance and repair costs. Current standard practice recognizes resistivity as a strong indicator of corrosivity of backfill materials. However, the existing AASHTO standards are primarily designed for fine aggregates. Thus, departments of transportation, like the Texas DOT, have attempted to revise these standards and propose adjustments to the test. At the same time, the application of alternative materials, such as expanded shale, clay, and slate, has gained popularity due to their lightness, ease of compaction, sustainability, and durability. The NASEM (2021) has highlighted the difference between normal-weight and lightweight aggregates concerning corrosion rate and resistivity. Therefore, there is a need to assess the efficiency of current practices and proposed adjustments for these alternative aggregates. The principal objective of this research project is to evaluate the current testing method to assess the corrosivity of expanded shale, clay, and slate aggregates compared to existing standards for normal-weight aggregates to enhance the service life and reliability of service mechanically stabilized earth walls in highway projects. For this purpose, a series of electrical resistivity and chemical tests on selected materials with various particle sizes will be conducted. Results will be compared with current standards to indicate the efficiency and reliability of the test.