Not something you can guess. It depends on the level of polish, the porosity of the concrete, the aggregate type...etc. It will make a difference whether it is wet or dry, as well.
Easier to test it and then you'll know. Assuming you are in the US, it can be field tested for about $150.
Ron is right, but BS8110 gives friction coeff't of 'smooth interface, as in untreated concrete' to be 0.7.
Polished concrete is bound to be less than that.
From the research I have done it turns out that by polishing the concrete you are creating a more dense surface. Therefore the coefficient increases and you have a more abrasive resistant flooring and a more slip resistant flooring than natural or raw concrete. I still dont have any numbers as to what it is but they are saying it increases by a minimum of 10%
mseely01....I have tested numerous floors and have found the opposite to be true. The coefficient of friction goes down as the roughness is reduced. For polished floors, I would expect the COF to be slightly more than 0.50 in the dry condition and less than that for the wet condition.
