Lexus Service Center

SGH visited the site to survey the floor system comprising a gravel bed, vapor retarder, slab-on-grade, and epoxy floor coating system. We documented the as-built construction and damage. SGH performed pull-off tests on the assembly and measured relative humidity and temperature of the concrete slab. We collected samples and performed the following testing in our laboratory:

• Petrographic analysis of core samples to identify characteristics and constituents of the assembly
• Microscopic evaluation of delaminated coating samples and pull-off adhesion test discs to review failed surfaces

We determined the flooring failed cohesively in the concrete’s near-surface, which was weak due to the concrete mix design combined with the curing, finishing, and surface preparation practices. SGH concluded impact from tools or parts dropped on the floor caused localized damage to the coating and concrete substrate, initiating coating delamination, and live loads, such as usual cleaning and traffic in the service area, propagated delamination.

SGH recommended repairs, including removing the epoxy coating and some of the concrete substrate, preparing and strengthening the concrete surface, and recoating the floor. We evaluated the recommended repairs by constructing and testing various mockups. We observed the flooring application and also measured coating adhesion, concrete moisture, and concrete temperature during the repair work.