Recycled Sandblast Grit
This technology incorporates spent sandblast grit into asphalt and concrete. The sand-sized grit is substituted for the “blender sand” that normally goes into these aggregates. During ship-cleaning operations, large quantities of spent sandblast material are generated. The material generally contains low concentrations of metals from the paints, anti-fouling compounds, and other coatings that are applied to ship hulls. In the past, much of this spent abrasive sand-blasting material has been disposed in landfills — in some instances it has been used as fill material on the shoreline.
Limitations and Concerns
Spent abrasive sandblasting material may contain a variety of materials that are not suitable for recycling, such as extremely toxic biocides and anti-fouling compounds.
There is a concern that the contaminants may leach out of the asphalt or concrete. The material to be recycled must be well characterized, and leach tests measuring the full range of contaminants must be incorporated into any recycling activity. Most state regulations require leach tests for only a relatively small number of contaminants.
This technology is used to recycle hazardous waste derived from surface-cleaning operations.
Technology Development Status
The Navy has conducted two recycling projects. A series of concrete test strips were produced to determine if they complied with California EPA policy on recycling waste into construction materials. The test strips had good physical integrity, and they met the Cal EPA and total threshold limit concentration (TTLC) and soluble threshold limit concentration (STLC) criteria for total and soluble metals content.
Other Resources and Demonstrations
This technology was demonstrated at Port Hueneme and Hunters Point Naval Shipyard.
See http://www.kleenindustrialservices.com/about.html for a commercial recycling service on the West Coast.