Roger Bisby does a half-hour job with Setcrete Rapidset 30
Every so often something comes along that really is a ‘dream product’ and Setcrete Rapidset 30 is definitely in that category. It sets hard enough to walk on in 30 minutes (at 20°C) and after 45 minutes you can lay the floor-covering.
It won’t take anyone involved in floor laying long to realise this is a game changer – not because it speeds the job up by a few hours but because it saves you having to return the next day – that is the real prize.
Up to that point a few hours saved on setting time was neither here nor there because, if you had to come back the next day, you weren’t really bothered if it took four hours to set so long as it was good to go the next morning.
Now you can lay the self-leveller, have a cup of tea and a bite to eat, check yout texts, and around 45 minutes later you can start sticking down the floor-covering. This will vary according to the depth which can be between 2-10mm and the temperature, which must be above 5°C. The times are based upon a temperature of 20°C.
How is this achieved? Where does the water go? So many questions, so little time.
Floor levelling (or smoothing) compounds use some clever cement technology, which gives them a non-shrink quality. They do this by holding the mixing water within the mix, which is why it is very important not to guess the amount of water you use.
If you put in too much, the excess water not absorbed by the powder will simply sit on the top and have to evaporate. The water to powder ratio has been worked out precisely to avoid this so you need to get a measuring bucket. This is not a product that you would use on large areas in commercial buildings but it is ideal for kitchens and other areas that can’t be out of action for too long.
The test area I worked on had been primed with Setcrete Acrylic Primer, which takes anything up to an hour to dry depending on the absorbancy of the subfloor and the room temperature.
The primer is important because it eliminates pin-holing and aids adhesion, and also prevents the moisture being sucked out of the mix. If the floor has damp problems, Setcrete also has a damp proof membrane. Both of these products can be applied with a roller. If the subfloor is absorbant the primer should be applied diluted.