ᐅ Turning Loose Fill into a Stabilized Fill Using Wallpaper Adhesive?

Many thanks to nordanney and superzapp

I add water to the cement-bound screed mix from the hardware store and stir it into a moist slurry. The water needs to evaporate before the next layer can be applied. There are no miraculous additives that guarantee even drying between the upper and lower layers.

The site is the upper floor, and we have timber framing throughout. This means it is well ventilated, and I have time to wait. Since I completed a similar project many years ago—creating a lightweight concrete ceiling by mixing polystyrene beads (used for beanbag filling) with cement-bound material, which worked very well and could be an alternative here as well—I am not worried but rather expect another positive “aha” moment with this new project.

I would have sprayed everything only with hairspray; where else would the granulate go after the ceiling is closed off? It will retain its intended properties 100% and fully perform its function. Once everything is dry and no deformation is observed, it can confidently be said that innovative approaches are still almost always rewarded today.

Thanks to all the fellow users following this closely

Regarding the costs again... how much does the wallpaper paste cost you in total, and how much do you need for the 10,000 L (10,560 qt) of loose fill? Just fill a wheelbarrow with this mixture—I want to know now.

By the way, I once read a DIY tip for pebble carpets... To practice, you simply coat the pebbles with wallpaper paste and use this to practice the application, practice, practice... Then wash it off before working with the real adhesive. I liked that tip.

Oh… Resin-bound stone flooring is really popular! There are also colored glass granules available in many shades. You can lay high-quality waterproof LED strips underneath, so the floor or stairs will glow from within. Just search online and you’ll be amazed.

My first attempt will take a little more time, but I don’t think the adhesive consumption will be excessively high since the material initially swells significantly. With only light wetting of the aggregate, the consumption should be reasonable. I have already found offers at €3 per kilogram of dry powder; 1 kilogram dissolved in water yields quite a large amount…

Phil333 schrieb:

I also add water to the cement-bound screed from the building supply store and mix everything into a wet slurry. The water then has to evaporate before the next layer is applied.

Cement sets due to a chemical reaction.
With the adhesive, drying actually needs to happen to remove the moisture.

Does the adhesive completely dry through at the desired thickness?

Are the properties of your dried slurry really comparable to a bound screed, at least regarding the relevant characteristics?

Why don’t you simply pour sand on top? It’s much cheaper, fills the gaps, can be compacted, and smoothed out.

Just the thought of mixing 10m³ (350 cubic feet) of loose fill by bucket makes my arms tired.
Why not simply use dry fill and be done with it?
For the next layer, I don’t see any need for a bound fill.

All subsequent work for the underfloor heating system based on dry screed takes place on a 3cm (1.2 inches) thick EPS board, into which grooves are cut to accommodate the pipes. This means that where the grooves are, only about 1.5cm (0.6 inches) of EPS thickness remains. So, everything is very thin-walled, and the localized knee and foot pressure is transferred directly through the EPS onto the sub-base (fill material). If this fill material is LOOSE or if I pour in sand, the loose aggregate underneath shifts sideways when stepped on. Try placing a polystyrene board on flat, leveled sand and walk back and forth on it. Everyone knows what happens in that case. Therefore, it only works with a firm sub-base. One advantage of using fill material is its insulating value.