Proline Decorative Concrete Systems TTR1800 18" x 18" Tumbled Travertine Square Tile Concrete Stamp. One of Prolines new Tumbled Travertine patterns is this 18 Inch x 18 Inch square tile pattern. This new addition to the Proline collection is unique because it showcases a texture that can be grouted. The tiles have a tumbled edge. A flat surface with all the texture recessed gives this pattern a Travertine appearance and allows the concrete to go sealed or unsealed for a more natural look.