The motivation for this research stems from the need for extending the service life, reducing the life cycle cost, and improving the safety and reliability of bridge abutments. This project endeavors to develop advanced solutions for the application of rotary-kiln manufactured lightweight aggregates in mechanically-stabilized earth (MSE) bridge abutments to extend the service life of bridges and reduce the need for maintenance and rehabilitation of bridges, abutments, and approach and departure slabs on roadways. This solution identifies cost-effective MSE systems to delay or eliminate corrosion damages for the long-term service life of roadways and bridges. The outcome of this research reduces the life-cycle cost, input energy, and greenhouse gas emissions associated with the construction, maintenance, and rehabilitation of MSE bridge abutments and other backfills involving embedded steel products. The innovative approach of this project is the evolution of current testing methods to measure corrosion of reinforcing steel elements as a function of electrochemical properties of backfill materials. This project extends and amends current national efforts led by the National Cooperative Highway Research Program (NCHRP), the American Association of State Highway and Transportation Officials (AASHTO), and several Departments of Transportation (DOT) highlighting past achievements in Fresno State and new possibilities for the State of California.
Califronia State Universit, Fresno
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.
SJSU Research Foundation 210 N. 4th Street, 4th Floor, San Jose, CA 95112 Phone: 408-924-7560 Email: firstname.lastname@example.org