Quick Answer

Exposed aggregate concrete can be polished to a smooth, decorative finish by grinding the surface evenly with coarse metal tooling, transitioning through medium grits, and refining with resin pads — taking care to cut the paste uniformly so the aggregate pebbles are revealed evenly, not gouged out. Stop at the grit that gives the look you want: matte at 100-200, satin at 400-800, gloss at 1500+.

How Exposed Aggregate Behaves Under Polishing

• Hard aggregate vs soft paste — the stone pebbles polish slower than the cement paste; the goal is a uniform plane.
• Uneven cutting — pressing too hard on one area digs out aggregate and leaves pockmarks.
• Grit sensitivity — the aggregate shows its own scratches, so every grit step must be complete.

Step-by-Step Process

1. Clean and inspect — remove debris; map soft or honeycombed areas that need repair first.
2. Grind level — use coarse metal-bond discs at 30-60 grit to establish a flat plane across aggregate and paste.
3. Transition — move to copper bond transitional polishing pads at 80-200 grit; the copper matrix cuts both paste and stone evenly, smoothing the surface without pulling aggregate.
4. Refine — polish with diamond resin polishing pads through 400-800 grit for a satin finish, up to 1500-3000 for gloss.
5. Densify and seal — apply densifier after the 200-400 step; seal or topically coat if stain resistance is needed.

Common Mistakes

Mistake	Result	Fix
Heavy pressure on one area	Gouged-out aggregate, pockmarks	Even passes, let the machine weight do the work
Skipping medium grits	Stone stays dull while paste shines	Complete every transition step
Polishing wet at high grit	Hazy aggregate	Dry-polish the final resin steps
Sealing too early	Sealer traps grinding dust	Vacuum and clean thoroughly before sealing

Frequently Asked Questions

Q: Can all exposed aggregate be polished?

A: Most can, but soft or poorly compacted aggregate can chip out. Test a small area first and repair honeycombed sections before polishing.

Q: What finish looks best on exposed aggregate?

A: A satin finish at 400-800 grit shows the aggregate clearly without glare. High gloss is stunning outdoors on patios and pool decks but needs maintenance.

Q: How do I avoid pockmarks when polishing?

A: Use even machine pressure, complete every grit step, and use transitional copper-bond pads so the paste and stone cut at the same rate.

Q: Do I need to seal exposed aggregate after polishing?

A>Yes, for exterior or wet areas use a penetrating sealer; for interior floors add a topical sealer if stain resistance matters. Sealing also deepens the colour of the aggregate.

Conclusion

Polishing exposed aggregate is about even cutting: establish a flat plane with coarse metal tooling, transition with copper-bond pads so aggregate and paste cut together, and refine with resin pads to the sheen you want. Done well, it turns a pebbled surface into a smooth, decorative, low-maintenance floor.