We are completing the casting of approximately 250,000 square feet of floors on grade in a large industrial plant. The weather has been so wet that we could not successfully protect them from construction traffic and they have become stained with natural red clay. Can you tell us of any economical and practical way to clean the stains from hard-troweled concrete doors? Expensive equipment has been set in some areas and consequently we must avoid detergents or cleaners containing strong acids.
In those areas where equipment has not yet been installed the best method would undoubtedly be to scrub vigorously with water containing detergent. If the clay has been so thoroughly embedded that it cannot be removed in this way, then a light acid wash using 1 part muriatic acid in 10 parts water should be effective. The floor should be thoroughly rinsed afterward. If the floor becomes unacceptably porous as a result it may be necessary to coat it with an epoxy resin floor coating or polyurethane floor coating. Both have good wear resistance. In those areas where equipment has been installed it may be possible to protect the equipment by using the kind of wet scrubber that has a vacuum attachment. The floor could be dry vacuumed first to remove anything that can be picked up in that way and then wet vacuumed.