The bases of 2 columns in my garage are corroding from salt & snow melt coming of the cars.
The columns are not embedded in the slab, but attached on the slab. I assume footer comes up to slab height.

I want to replace these two columns, but actually raise the base up about an inch or two, to eliminate future corrosion. This is a 2400 square foot 2 story house plus attic, so I'm not just going to throw a concrete block under there to keep the new post off the ground.

I need ideas. Cut floor, expose footer, add rebar and increase height of footer to include this additional 1-2" off the finished slab height?

Bonding would be better if you cut down into the concrete a bit. However, sometimes they drill small holes, set rebar pins and rebar and build a retaining form with 2X2. Use high strength concrete mix. How are you planning to support the beam when you remove the old columns?

I'll support the beam with a jack post on either side of the column I'm replacing while I do the work.

Thanks for the tip, I'll look into both of these ways. I like the idea of either cutting down into the slab an inch or two, then pouring a new pier locked into that form.

That would give you the most secure footing.