What is broom finish concrete?
After the concrete has been poured and levelled, a stiff broom is used to give it a rough surface. This process is known as broom finishing the concrete.
Also called brushed concrete, broom finish is one of the several concrete finishing techniques that are used for getting different results with concrete.
A broom finish is unlike finished concrete that has a smooth surface.
How long should I wait after levelling the concrete to broom finish it?
Wait for all of the water content to disappear before broom finishing concrete. Depending on the humidity, temperature and wind condition, you may have to wait anywhere from 30 minutes to 5 or 6 hours.
Once all the water has bled out, you can take out the steel finishing trowel. The new concrete surface is ready for the final touches.
What are some other types of concrete finishes besides broom finish?
As discussed earlier, you have several options when it comes to concrete finishes:
- Troweled finish
- Exposed aggregate finish
- Salt finish
- Stained concrete
- Polished concrete
What types of concrete surfaces are usually broom finished?
Decorative concrete surfaces are usually not broom finished. This includes interior concrete surfaces like floors of the living room and bedroom. Stains and dyes are some of the more popular finishes for this type of concrete.
You can apply dyes and stains to broom finished concrete too, though. At the same time, it is also ‘possible’ to broom decorative and stamped concrete, but that is more difficult to achieve.
Only in cases where a powdered release agent is used to achieve the stamped finish is it impossible to broom finish the concrete surface.
If you are thinking of brooming your decorative concrete to make it slip-resistant, there are other ways of doing it as well.
What does a typical broom finish process look like?
The broom finish process usually involves the following steps:
- Pour the concrete slab
- Strike off the concrete with a screed
- Level the concrete using a bull float
- Broom the concrete surface.
- Cure the concrete
- Seal the concrete. This step is for broom finished decorative concrete only.
a. Wait for the concrete to bleed out. Exterior concrete having low water-cement ratio in proper conditions may not have much water to bleed.
b. Bleeding occurs as the wet concrete settles and gets trapped with air particles that prevent concrete from settling properly, causing some of its water content to bleed out.
a. There are varying opinions in concrete builders when it comes to the use of a trowel for a surface that is getting broom finished.
b. Some finishers skip trowelling altogether. They just bull float and broom.
c. While there’s no need for too much finish using a trowel, you should still consider trowelling once or twice before the broom finish.
d. It is also recommended that you broom right after the second trowel.
e. Keep in mind that the more you trowel, the harder it gets to broom finish the surface.
f. If the trowelled surface becomes too hard, you can consider using a damp broom for the next step.
a. If there is a slope, you want the broom running perpendicular to the slope.
b. If there is a drain, have the broom running towards the drain.
a. Concrete curing is recommended for broom finished concrete.
b. Cure the concrete by spraying a curing compound or using polyethylene sheets.
c. When working on plain gray concrete, many builders tend to add white color to it so they can see where it’s been applied. The color dissipates in a few weeks.
How to achieve the best broom finish results?
Mastering the broom finish takes time. It’s more of an art than science really. Some builders create stunning effects and patterns by running the broom in ways that they have perfected over the years.
Have the broom running from side to side without stopping.
When working with a standard broom, follow this simple technique:
- Pull the broom toward you
- Lift and take the suspended broom back to where you started.
- Pull the broom toward you again.
- Repeat these steps as you gradually move from patch to patch until the entire concrete surface is neatly broomed.
What kind of broom do I need?
There are many different concrete brooms on the market that come in different widths and configurations. Some are designed to offer varying levels of texture.
The block holding the bristles of the broom is made of plastic, wood or aluminum. Plastic blocks are popular because they don’t warp or rust.
The bristles of a concrete broom are made using different materials, including horsehair, nylon and polypropylene. They come in different sizes and stiffnesses for achieving different textures.
Wire combs may be used for extreme textures.
Other broom types include handleless brooms and brooms that attach to a bull float.