In our previous blogs, we described several mechanical poker vibrators in detail. But once the concrete has been compacted, we still need to go through more steps to achieve a high-quality finished product. So I’d like to write a bit about the next step: levelling (and finishing) the compacted concrete.
What is a wet screed?
A wet screed is a tool for smoothing out compacted concrete in order to achieve a perfectly finished floor. Once the concrete is compacted, you should immediately begin finishing the surface.
Illustration 1: a compacted, but unfinished concrete floor
That’s because a certain quality of finish (for strength, durability, etc) is required, and concrete is still very malleable after compaction. The finishing work involves two elements. First, the concrete is brought to the correct height, using a vibrating beam, a roller screed or a smoothing bar.
Illustration 2: levelling with a smoothing bar
Once the concrete has been brought to the correct level, the top layer can be smoothed out. This is usually done with wet screeds.There are a vast number of wet screeds on the market, with a wide variety of dimensions, materials, weights and vibrating options. But basically, wet screeds can be divided into a few different types:
- Hand trowels (without handles)
- Push screeds (with handles)
- Vibrating screeds
You can find hand trowels (without handles) at any concrete pour. They are the ideal tool for smoothing minor imperfections in the concrete surface immediately after it has been levelled. In the past, people would use trowels to finish the floor once the concrete had cured for a bit. Several craftsmen would be down on their hands and knees levelling the surface of the concrete. But today, we use power trowels instead. But the hand trowel is still good for finishing the edges along a wall, once the coarse work has been done by the power trowel.
The push screed with handle is often used as the last tool to put the finishing touch on the concrete surface while it is still malleable. That is because the top layer has to be smoothed out to give it a neat appearance. The long handle allows workers to avoid walking across the freshly poured concrete.
I like to compare it to using a butter knife to spread an even layer of butter across a slice of toast. And like butter, concrete can only be smoothed out before it hardens. In practice, the concrete can start to cure quickly, which makes it more difficult to smooth out. So I’ve seen some resourceful craftsmen place a heavy rock on the screed to increase the pressure while smoothing.
Illustration 3: finishing concrete with a push screed with handle
The vibrating wet screed is the variant that we build here at Lievers. This type differs from other screeds and trowels in that it has a motor that causes the screed to vibrate. These vibrations make it much easier to smooth out the surface, because the craftsman doesn’t have to exert as much pressure on the wet concrete. The vibrations cause the screed to ‘float’ over a thin layer of water that vibrates up to the surface of the concrete. So all the craftsman has to do is move the vibrating wet screed over the surface to get a perfectly smoothened finish.
Illustration 4: easy finishing work with our vibrating K150 wet screed
In my next blog, I’ll go into more details of the vibrating wet screed, and why using one improves the quality of the concrete.