Utilization of pneumatic flow tube mixing technique (PFTM) for processing and stabilization of contaminated soft sediments in the NY/NJ Harbor

A pilot study was conducted to evaluate the use of the pneumatic flow tube mixing method for stabilization and solidification of soft sediments dredged from the New York/New Jersey Harbor. The study included a comprehensive laboratory investigation aimed at determining the ideal mix for pneumatic flow tube mixing stabilization, and a pilot-scale demonstration of the pneumatic flow tube mixing technique in the field. Material stabilized during the demonstration was analyzed through unconfined compression tests, needle tests, laboratory vane shear tests, and flow tests in the laboratory and the cone penetration test in the field. Curing times for the samples were 3, 7, 14, and 28 days. The three cement content mixes were 4, 8, and 12% by weight (wet weight). Pneumatic flow tube mixing was demonstrated to be an efficient and rapid method for soft sediment stabilization with the resulting material showing uniform quality of mix meeting, New Jersey Department of Environmental Protection's geotechnical and environmental fill placement criteria.