If your Lincoln Memorial penny has a date before 1982, it is made of 95% copper. If the date is 1983 or later, it is made of 97.5% zinc and plated with a thin copper coating.
first they should of prepped and patched that floor. The pennies that are over that expansion joint will eventually pop. 2nd, they'd be smart to epoxy it in order to fill all the voids. Finally, a good polyurethane would finish it off nice.