Copyright Goodheart-Willcox Co., Inc. Chapter 3 Tools and Equipment 43 Tampers, darbies, and bull floats all have a similar purpose, which is to aid in pushing exposed aggregate below the surface of the concrete and to bring a thin layer of liquid concrete (cream) to the top. This layer is troweled later in the process to create a smooth, hard finish. Figure 3‑45 shows a rattle stick, a device that is at- tached between the bull float bracket and the handle. The rattle stick vibrates when turned on to aid in driv- ing the aggregates below the surface in the mixture. The rattle stick also assists in bringing the concrete cream to the top to create a smooth surface on the concrete with less time spent. 3.3.5 Edgers Edgers are tools used to produce a radius on the edge of a slab. Several sizes and styles of edgers are available. See Figure 3‑46. A typical length is 6″, and widths vary from 1 1/2″ to 4″. Edgers have radii from 1/8″ to 1 1/2″. The radius improves the appearance of the slab and reduces the risk of damage to the edge. The curved- end edger is very popular. 3.3.6 Groovers Groovers are used to cut a joint partly through fresh concrete to control the location of any possible cracks. See Figure 3‑47. The purpose of the joint is to weaken the concrete so cracks will occur at the bottom of Rattle Stick ConcreteTools Figure 3‑45. The rattle stick uses a quick attachment to connect to the bull float and handle. Stanley Goldblatt Figure 3‑46. An assortment of edgers used to produce a radius on edges of concrete slabs.