Cheng Concrete Exchange introduces a new line of concrete countertop products—Cheng Concrete Countertop Products. The Pro-Formula mix combines color, strength, and workability while the slurry backfills voids. The sealer offers a streak-free finish with a natural luster and the wax results in a lustrous shine and polish. Finally, the polish forms a protective layer on the concrete. Cheng Concrete Exchange. 510-849-3272. .