cdm123
Senior Member
They sprinkle steel fillings on as it setts and trowel them in to the surface, it makes it very hard to chip.Worked in a garage where the concrete had steel filings and iron dust mixed into the batches. Took a diamond blade or drill bit to cut it after hardened, had a dark grey color once dried and would develop a rust sheen if left wet for long periods. We ran crawlers on these floors with minimal grouser damage but when came time to replace due to age was major SOB to remove the slabs.