Architects specify patterned concrete surfaces for the aesthetic interest generated by a play of light and shadow, or to simulate economically in concrete the traditional patterns of brick, stone, and wood. A patterned concrete surface does not reveal so plainly minor imperfections that can mar a smooth concrete surface. And rougher concrete surfaces are often easier to maintain.
Basic forming materials such as plywood, lumber, and steel may be used as form liners. Paper, rubber, cardboard, and even concrete panels have at times served as liners. Some of the most widely used liners today, however, are made of textured plastics or polystyrene. The choice of liner material may depend on whether the work is cast in place, precast, or tilt-up.
A textured or patterned form liner can produce high-quality architectural concrete, but only if joints in the forms and liners are done carefully, and the liner materials are handled properly. Be sure that liners are compatible with release agents and adhesives and that temperature-related movement of the liners is designed for. Proper placing and consolidation of concrete are essential to good results with patterned form liners.
Above all, make certain that construction practices are consistent from one lift to the next.