All Aboard Florida MSE Walls
All Aboard Florida (AFF) plans to offer an express train service between Miami and Orlando, Florida. A new 40-mile track will be built, and a number of mechanically stabilized earth (MSE) walls will be incorporated along the new track. Fill for the MSE wall construction will be sourced from four possible on-site borrow pits. Material from these sources were evaluated and compared to the requirements specified for MSE wall fill. Suitable soils for MSE wall construction were identified at each borrow pit location, however, a large quantity of the material falls outside the requirements for electrochemical properties. When the electrochemical parameters of fill materials used in construction are not within the required limits, rates of metal loss used to asses service life and sacrificial steel requirements during design need to be revised accordingly.
ERTesting at McMahon & Mann Consulting Engineers, P.C. was engaged to evaluate the electrochemical parameters measured from each borrow pit and recommend revised metal loss models to use in design considering the use of galvanized steel reinforcements. ERTesting reviewed and performed statistical analyses on the electrochemical test data, and reviewed existing performance data describing the effects of pH on the corrosion rates of galvanized steel elements, and identified the range of measured corrosion rates for galvanized steel reinforcements corresponding to the properties from the four borrow pits. ERTesting also estimated the reliability of meeting the intended service life, and prepared a report with recommendations and conclusions for designing and construction of MSE walls using fill material from the four borrow pits.
