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A study to evaluate corrosion rates was conducted using pile foundations abandoned during the reconstruction of I-15 through Salt Lake Valley, Utah. Corrosion rates were measured for 20 piles extracted from five sites after service lives of 34–38 years. Measurements were made of soil index properties, resistivity, pH, cation/anion concentrations, and water table elevation. The critical zone for corrosion was typically located within the groundwater fluctuation zone; but correlations with soil properties were generally poor. Despite low resistivity, average corrosion rates for pile caps in native soil were typically between 2 and 9 μm/year with a maximum of 19 μm/year and did not pose any structural integrity problems. Nevertheless, for abutment piles where chloride concentration was very high, the average pile corrosion rate increased to 13 μm/year within the embankment and the maximum corrosion rate was 48 μm/year in the underlying native soil. Based on data from this and previous studies, equations were developed to predict maximum corrosion loss for piles in nonaggressive soil as a function of time. [ABSTRACT FROM AUTHOR]

The I-15 Reconstruction Project in Salt Lake City, Utah required rapid embankment construction in an urban environment atop soft lacustrine soils. These soils are compressible, have low shear strength, and require significant time to complete primary consolidation settlement. Because of this, innovative embankment systems and foundation treatments were employed to complete construction within the approved budget and demanding schedule constraints. This paper evaluates and compares the construction time, cost, and performance of three embankment/foundation systems used on this project: (1) one-stage mechanically stabilized earth (MSE) wall supported by lime cement columns; (2) expanded polystyrene (geofoam) embankment with tilt-up panel fascia walls; and (3) two-stage MSE wall with prefabricated vertical drain installation and surcharging. Of the technologies evaluated, the geofoam embankment had the best performance based on settlement and rapid construction time considerations, but is more costly to construct than a two-stage MSE wall with PV drain foundation treatment. The one-stage MSE wall with lime cement treated soil was the most costly, and did not perform as well as expected; thus, it had only limited use on the project. [ABSTRACT FROM AUTHOR]