Glauconite is an iron- and potassium-rich mineral of the mica family. It evolves at the soil-water interface through chemical exchange, its maturity linked to exposure duration at the seafloor and source element availability. Glauconite sands have been discovered at offshore wind lease areas along the U.S. Atlantic Outer Continental Shelf, leading to uncertainties in pile foundation installation and long-term performance. This paper describes site characterization activities from the Piling in Glauconitic Sand (PIGS) Joint Industry Project test site, located along the New Jersey Coastal Plain. In situ testing, laboratory-based geological, microstructure, and soil index testing, and advanced soil behavior measurements are presented in detail. Comparisons to selected silica sand-based cone penetration testing (CPT) correlations are made, highlighting the cautions needed for deriving soil parameters in this unique material. The measured properties and observed behavior exhibit a transition from sand-like to clay-like behavior during particle crushing due to compression and shear stresses from impact pile driving, which deviate from conventional sedimentary clays and sands. This transition can lead to changes in soil microstructure, plasticity, strength, and permeability, among others. The extensive dataset provides a reference for geotechnical practioners and researchers encountering other glauconite sand deposits or similar transitional sediments.
Westgate et al. (Fri,) studied this question.