Making Concrete Slip Resistant
Concrete finishers have been broom finishing their surfaces for about as long as there has been concrete. Typically decorative concrete surfaces are not broom finished, although dyes and stains can be applied very successfully to broomed finishes. Even stamped finishes can be broomed, although that's a bit difficult—impossible if you are using a powdered release agent. There are better ways to make stamped surfaces slip resistant, which we will get into later.
The typical process for a broom finish is:
A good broom finish is something of an art. You can even create decorative effects by running the broom texture in various directions. Typically the broom should be run from side to side of the concrete without stopping. With a standard broom, you should pull the broom towards you, then lift it and set it back on the far side to pull it across again. Marion Brush makes a brush (the Auto Glide) where the head automatically tilts to the correct angle, so you can get a good broom finish whether you are pushing or pulling the broom.
Brooms are available from a variety of sources. They come in various widths and the block that holds the bristles can be made from wood, aluminum, or plastic. Brooms tend to be wet a lot and the plastic blocks (high-density polyethylene) won't rot or warp. Bristle materials can be horsehair, polypropylene, or nylon and come in various stiffnesses and sizes to produce different textures. For extreme textures, wire combs are available to produce tined finishes.
Marion Brush Co. specializes in concrete brooms. Their president, Gary Bolden, says that "there are a lot of variables in getting a good broom finish: the slump of the concrete, the weather (sun, wind), and the timing. Every contractor has a tendency to do a slab in their own way. Some might broom sooner than others. Some may pour and broom finish and use a softer brush so they can get on the slab sooner." Marion's Chameleon concrete broom allows you to change out an insert to get different textures or to adjust to conditions. The color-coded inserts come in five textures from supersoft to rough.
Marion's concrete brushes are made from 612 nylon, which Bolden admits is one of the most expensive materials used for brooms, but which he says will outwear other materials by 3 or 4 times. The other advantages of this nylon are that it stays cleaner during use and that it has a memory. No, it can't remember your phone number, but if the bristles get bent, you can pour boiling water on them and they will return to their original shape.
A couple of other interesting kinds of brooms are handleless and brooms attached to bull floats or fresnos. The handleless brooms are pulled back and forth across the surface with ropes—Marion Brush and Cleform make these. This invention is especially handy on very wide pours where it would be difficult to push a broom all the way across and where the bull float handle begins to get so heavy that it pushes the broom too deeply into the concrete. Also available from Marion are brooms attached to bull floats or fresnos. This allows the float to support the weight of the handle rather than the broom. Bolden says that this positions the broom so that the finish is made by the sides of the bristles rather than the tips, which provides a more uniform finish.
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