There are a number of tools used to finish concrete. Knowing what each is for and the order they are used is critical for a pleasing and structurally sound surface. Though there are always exceptions to the rules, here are the must-have tools in the general order of use.
Once concrete is placed, a strike-off tool is used to level it. Also called a screed or straight edge, they come in aluminum or magnesium and the most common size is 2”x4” in a 16’ length. Magnesium is, in essence, “glorified aluminum.” It is stronger but lighter meaning less operator fatigue. When purchasing a straight edge, you need to know:
- Desired length
- Preferred size: 1-1/2” x 3-1/2” (ideal for smaller hands) or 2”x4”
- Material: Aluminum or magnesium
Finishers use a concrete placer or rake (called a come along) to move the concrete into place, against the straight edge, during the screeding process. Come alongs are usually a steel blade with wood handles or can be entirely aluminum. The latter, being lighter, causes less operator fatigue. Some options include a hook used to pull the wire mesh up into the concrete.
After screeding, hand floats (i.e., mag floats) are used to work the edges and bull floats are used for the larger areas to further flatten and level the concrete. The primary purpose of floating is to settle the large aggregate, or rock, and bring the cream to the surface. The longer the float, the better chance of achieving flatter surfaces. Bull floats – which are aluminum, magnesium or wood – have handles and brackets, conventional or swivel for easier pitching. While floating, the blade should be kept as flat as possible. Wood floats are better suited for non-air-entrained concrete, with high-slump concrete and when topical hardeners are used as they keep the surface open and allow bleedwater to surface sooner. Magnesium floats are durable and easy to slide across a surface. Channel radius floats are the most preferred type because of their rigidity. Rounded edges prevent overlap marks.
A darby is a long hand float (typically 28” to 45”) usually made of wood but can also be magnesium. They are usually used while edging and are often used with curb work.
Edgers are used to create professional, rounded edges on the side of a concrete slab. Typically made of steel or bronze, they come in different radiuses for difference edges (for instance, an edge of a curb or step would be a larger radius).
Groovers are used to create control joints to prevent random cracks. Also called jointers, groovers are most commonly used on driveways or sidewalks in residential construction.
A fresno, made of carbon or blue steel, should be used after bull floating to further smooth and seal the slab. Fresnos can be used from the edge of the slab so finishers don’t have to walk out onto the concrete. Generally used for paving, they are 24” to 48” long and 5” wide. A wide fresno, called a Big D float, is 12” wide and typically 4’ or 6’ long. Various brackets and handles can be used. A super trowel, or California trowel, is similar to a fresno but made with a pool trowel, with rounded edges, and swivel brackets.
Hand trowels are used to seal the concrete surface after bull floating and before broom finishing or to slick finish the concrete. It’s all about the angle and the pressure when it comes to hand trowels. They should be used at a slight pitch, increasing as the concrete hardens. The most popular trowels are carbon steel 4”x16”.
Concrete finishing brooms can be used to create a light texture on concrete paving, sidewalks and driveways. They are used to create safer non-skid surfaces. In general, if you’re brooming in the winter and the concrete is soft, you want a soft-bristled brush while in the summer, when concrete is setting fast, you want a stiffer broom. There are many brush options that result in different textures and looks. The most commonly used finishing broom is a thin block 48”.