Strengthening an existing 20-PSI mine seal with PPG's polyurea coated retrofit.
Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Contract 200-2007-20426, 2008 Aug; :1-146
Analysis and testing have been completed for utilization of polyurea coating in a mine seal application to improve blast effectiveness of the mine seal. The MICON 550 seal was selected for analysis and testing for the polyurea coated modification. The baseline seal used two walls of dry stacked solid concrete blocks separated by a 16" thick polyurethane core. The unmodified seal was an approved 20 psi mine seal. The program goal was to increase the mine seal blast pressure sustainability of a baseline 20 psi seal to greater than 60 psi. A coated retrofit design was developed for the Micon 550 seal which includes a secondary 8" thick polyurethane core, secondary block wall, and .125" thick polyurea coating. The retrofit configuration was installed and tested at the Lake Lynn Experimental Mine, and survived a blast test with a peak blast pressure of 78.5 psi with permanent displacement of one inch. A second test was conducted after reinforcement was added by bolting heavy steel angle to the floor on the outby side of the retrofit; the modified retrofit survived a second blast test with a peak blast pressure of 84.4 psi with total permanent displacement of 3 inches. An alternative seal design was also analyzed with and without polyurea coating. A solid concrete block seal was selected for analysis. The uncoated seal was rated at 50 psi, and was predicted by the models to fail at 70 psi peak blast pressure. The coated seal was predicted to survive a minimum 90 psi blast using conservative predictions of potential coating failure. The completed analyses and testing have shown that the PPG polyurea coating can be used to improve the blast protection of mine seal structures.
Analytical-processes; Coatings; Mine-seals; Mining-industry; Explosions; Underground-mining
Final Contract Report
NTIS Accession No.
Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Contract 200-2007-20426
PPG Industries Coatings Innovation Center, Allison Park, PA