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The contractor does not know the concrete mixture proportions, setting time, or bleeding rate and duration. Although these sample panels exhibit a consistent texture and appearance, they give the contractor little beneficial information. Specifiers sometimes create their own reference sample, usually about 0.3 to 0.6 m x 0.3 to 0.6 m (1 to 2 ft x 1 to 2 ft), to show the contractor the texture and appearance specified for the project.

If the owner elects to place narrow strips for the parking garage slab to achieve a more consistent result, the trade-off is increased cost and a longer schedule. Specifiers must recognize this inherent difficulty with different-sized concrete placements and owners must realize that while the larger parking garage placements cost less and shorten the schedule, they will not have the same appearance, flatness, texture, and drainage as a sidewalk. What is possible to produce on a 1.2-m (4-ft) wide sidewalk surface is impossible for a large-scale parking garage surface. As the concrete placement size increases-from a 1.2 x 30.5-m (4 x 100-ft) sidewalk to a large-scale parking garage placement of 930 m 2 (10,000 sf), for example-it becomes more difficult to produce a consistent appearance, flatness, texture, and drainage. With smaller concrete placements, more consistent brooming results can be expected. These requirements vary from project to project because of the wide variety of exterior concrete surfaces with a broom finish, including:Ĭontractors can achieve many different specified broom finish characteristics, but the most important issue often affecting achievability is the size effect. The most common method for this is specifying a ‘broom finish.’ But, is that all there is to it? Specifications must also satisfy owner requirements for appearance, flatness, texture, as well as drainage. Suprenant, PE, PhD, and Frank Salzano, PEĪs a safety requirement, all exterior concrete surfaces must have a slip-resistant surface. Photo courtesy CECO Concrete Constructionīy Bruce A.