how do you polish concrete without having bumps over the aggregate?

Question

The aggregate is generally harder than the surrounding cement and polishes more slowly than the concrete. Therefore the final product is not a completely smooth uniform surface.

Answer 1

The only way to do this is with a grinder that is used to finish terrazzo (sp?) floors.

Answer 2

Step 1: make your concrete form
Step 2: Mix and pour the wet concrete into the form
Step 3: Using a garden rake, rake the concrete to the edges of the form and make it fairly level

Step 4 (answer to your question): There is a special tool -- I call it a tamper. It is a metal screen with handles attached. You use this to push the aggregate down and then the "cream" rises to the top through the screen mesh. The "cream" is the cement and the sand. It only takes a fraction of an inch of "cream" to allow you to smooth it out without bumps.

You can usually rent all the concrete tools you need at a tool rental store.

Step 5: after tamping down the gravel, use a large "float" to start smoothing out the concrete. On a large area, usually someone is tamping down one area, while another person is starting to smooth out the tamped-down portion. For REALLY large areas, it would be best to rent a power-float.

Step 6: If you want a "mirror" smooth finish, you have to work with a hand-float. Use plywood on the floated portions, get on your hands and knees and start working the concrete to smooth it out even more.

Step 7: don't forget to wash off your tools, because hardened concrete is almost impossible to remove.

Answer 3

Freezing was aggravated by the presence of deicing salts.
The American Concrete Institute
See link below