Copyright Goodheart-Willcox Co., Inc. Chapter 18 Concrete Flatwork and Formed Shapes 395 6. Continue to stamp the rows of concrete until the slab is completed. 7. Perform detailing work, completing joints by hand where the stamping forms cannot access or when the coursing begins to meet the perimeter stamping. 8. Remove residual concrete, extra release agent or curing compound, and any other foreign materials from the slab. 9. Install control joints. Cutting with a power saw usually works best. Cut to a depth of one-fourth the thickness of the slab. 10. Seal the surface of the concrete according to the manufacturer’s specifications. Nonslip and Sparkling Finishes Nonslip finishes can be applied to surfaces that are frequently wet or are especially dangerous if slip- pery. Abrasive grains can be dry-shaken on the surface and lightly troweled. The two most widely used abrasive grains are silicon carbide and aluminum oxide. The silicon carbide grains are sparkling black in color and are also used to make “sparkling concrete.” Aluminum oxide is usually gray, brown, or white and does not sparkle. The grains should be spread uniformly over the surface. Use from 1/4 lb to 1/2 lb of grains per sq ft of slab surface. Combination Finishes Concrete is a versatile material. It can be applied in many ways to create a beautiful walk, drive, or patio to complement the style of any architectural design. See Figure 18-33. Striking effects can be attained by combining several colors, textures, and patterns in concrete. Alternate areas of exposed aggregate and plain or colored concrete provide an exciting combination. Ribbons and borders of masonry or wood create a dramatic effect with plain concrete or exposed aggregate surfaces. Cast-in-Place Concrete Walls Cast-in-place (CIP) concrete walls are made with ready-mix concrete that is transported to the jobsite and placed into forms that are erected on the site. Cast-in-place concrete permits structures of all shapes, sizes, and heights. Exterior wall surfaces can be rough or smooth, natural or colored. Popular types of cast-in-place (CIP) concrete walls include rustic, grid-patterned, colored aggregate, window walls, and sculptured. Rustic Concrete Walls Rustic concrete walls can be produced by using rough form boards, bush hammering the surface, or casting vertical fins in the concrete surface. Trade Tip Bush hammering exposes the aggregate that lies just beneath the surface of the concrete. The process is usually performed with a special hammering tool that removes the outer surface of the concrete to expose the aggregate, leaving a rough exterior texture to the concrete. Bush hammering is usually performed three to five weeks after the concrete is poured to ensure that the surface is adequately hardened. Forms made from rough-sawn boards have been used for years to produce a textured surface in concrete walls. See Figure 18-34. Imagenet/Shutterstock.com Figure 18-33. The concrete driveway has been stamped and colored to complement the architectural design of this home.