Polished concrete: existing slab-on-grade or topping slab ground progressively with diamond tooling. Levels: cream polish (surface only), salt-and-pepper (fine aggregate exposed), medium (medium aggregate), full (coarse aggregate exposed). Process: coarse grind (50-100 grit) → densifier (lithium silicate) → fine grind (200-800 grit) → sealer. Hardness: 6-7 Mohs after densification. Maintenance: dust mop, neutral cleaner. Stained: acid or dye coloring before sealing. Cost: $3-$12/sf (varies by level and existing slab condition). CSI 03 35 43. Advantages: no material on top of slab, thermal mass for radiant heating, hypoallergenic, zero VOC. Disadvantages: cold, hard, can be slippery when wet, cracking follows slab joints.