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96 JANUARY 2017 COATINGSPROMAG.COM Never Again Shortly after a new maintenance center was built, the epoxy floor coating could be seen coming off in sheets. A thin layer of concrete was observed on the bottom of the delaminated coating. The Case of the Car Dealership Floor Failure By Emily R. Hopps, P.E., Senior Project Manager, and Peter E. Nelson, P.E., Senior Principal, for Simpson Gumpertz & Heger Inc. S urface preparation and evalu- ation of concrete substrate conditions are critical to the successful installation of an epoxy floor coating system. Improper concrete slab composition, finish- ing, curing, and surface preparation can lead to delamination and overall system failure. T he case of a failing car dealership f loor coating was no exception. T he project building was constructed w ith a sales showroom and a large on-site ser vice and maintenance center w ith an epox y f loor coating. Shortly after the building opened, workers in the ser vice and maintenance center obser ved delamination of the epox y coating. Delamination seemed to originate where heav y tools and parts were dropped on the f loor. Vehicle traffic propagated the delamination, and large sections of the coating could be removed in sheets. A thin layer of concrete material was ty pically obser ved on the bottom of the delami- nated coating. Moisture and soft resin materials were not found at the delam- ination areas. Cou ld t he fa i lu re be solely at t r ibuted to t he c a reless d roppi ng of tool s, or wa s somet h i ng el se to bl a me? Project History e concrete slab-on-grade in the facil- ity was placed in March over a 6-mil (152.4 microns) polyethylene vapor retarder membrane and gravel bed. e concrete mix included a 1 percent non-calcium chloride accelerator and no air entrainment additives. e installing contractor reported that the concrete was placed using motorized buggies and was hand-raked and set level with the use of a power-augured Photos courtesy of Simpson Gumpertz & Heger Inc. Improper concrete slab composition, finishing, curing, and surface preparation can lead to delamination and overall system failure.