Surfactant-Induced Soil Strengthening (SISS)-A Potential New Method for Temporary Stabilization along Beaches and Coastal Waterways

In recent years, a new method for soil stabilization was discovered that involves combining an anionic surfactant with alkaline earth metals. Combination of these ions with soil creates a matrix that adheres soil particles together and leads to improved strength. This soil improvement method has been dubbed surfactant-induced soil strengthening (SISS). In this study, beach sand from Atlantic Beach, FL, was strengthened via SISS by hand-mixing various combinations of sodium dodecyl sulfate and calcium chloride. Specimens were tested for strength improvement using unconfined compressive strength testing. Results showed that significant strength improvements may be possible using this method, and an approximate optimization point was established as a function of pore volume. Next, a surface percolation treatment method was tested using bench-scale sandboxes where surface erodibility and strength were tested using a modified rut erosion test and pocket penetrometer. Results showed that surface percolation may increase soil strength and reduce erodibility associated with vehicle tires, but surface percolation is much less effective than hand mixing. In addition, results from sandbox testing appeared to show that calcium mobilization is much more important than stoichiometric balance in terms of realizing strength and tire erosion improvement. Finally, dissolution testing was conducted on several specimens. Results showed that soils treated via SISS tended to revert to their untreated state over time in the presence of freshwater and saltwater.