Convert loose fill into bound fill using wallpaper paste?

Unfortunately, I have to do a very large area with it

The effort alone is not worth it. How do you want to get a homogeneous mass by the cubic meter? And in what time? Doesn't the stuff mold from underneath? Etc.

I have to apply a layer of about 3-5cm over 220m2 area (so about 10,000 liters) and unfortunately only "3cm EPS" goes on top of that. And later grooves will even be cut into the EPS for heating pipes. (Dry screed) Then heat-conducting plates. Then pipes in. Then Fermacell boards. For all this work, the substrate should not be trampled or deformed. Therefore, a stable BASE structure where nothing crumbles, shifts, or dents when walked on. I also have to mix bonded fill, then just cheap loose fill and simply be innovative myself. That was my thought. Wallpaper adhesive, when hard, holds extremely well! Maybe the industry used the same substance as wallpaper adhesive, just called X23SP7 special adhesive. I'm not obsessively concerned about money but still about money. I want to try a little and be happy with the same result. Bonded fill 27€ = 80L x 125 bags = 3375€ Loose fill 13€ = 100L x 100 bags = 1300€ 2075€ difference = what is that for, please? I have now found wallpaper glue for 3€/1kg. Bonded fill is optionally cement-bound, which I also have to mix in a bucket. But instead of cement or tile adhesive additive, I would like to try wallpaper glue. Because once that stuff is cured, then the fun is really over. I'll just make a test area and then the result will reveal itself. Of course, I will only add as much glue as to keep the pores of the fill granulate open for drying.

or I'll just delete the account here again.

Not the worst idea

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I'll just create a test area and then the result will reveal itself.
....
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Possibly consider that you will NEVER get back to it if the floor structure is not to be completely destroyed. The effort for a renovation will be significantly higher than the "small" difference of 2000 euros currently. Unfortunately, I have experience with long-term unsuitable material in the ground (250-year-old house with a lot of "botched work" in walls, floor, and roof). Chemical processes that may only be triggered late (years later?) ... just something to think about whether the risk is worth it. The construction industry does this not only to make money but possibly also because it has proven effective?

Best regards
zapp

So you want to mix 10000l of sludge, smooth it out, and then cover and seal it with Styrofoam? That is one of the worst ideas imaginable on every conceivable level.

....and if the previously "dried & cured" paste (whether original industrial paste or homemade paste) eventually breaks and crumbles 10,000 times in the ground, which will definitely never happen, then we more or less have the following result again= "wonderful, marvelous loose filling as originally planned". So it can only transform from its finished inherent form from good to good.

When the ground is closed and finished, who still cares whether it is bonded or loose?
When the Fermacell boards are on it and the tiles, it is like a heavy marble coffin lid.
Then there is peace, come what may!

I can already hear the scoffers: for God's sake, are you crazy, because the granulate will start talking, or singing or squeaking at some point.

And look here, aren’t we all searching for a special value or advantage during the construction phase, just with registering here in the forum alone?
If I say I will transfer the saved amount of €2075.00 to the members of this thread, then it is exactly these cool wisecrackers who immediately post their IBAN.

How many worthless and fruitless comments has the forum accumulated over the years from those people who basically always only deliver elitist, unsubstantial opinions and wisecracks, but are practically infantile system people who never leave the open birdhouse to learn or experience "more" and SHARE this, and therefore cannot or barely can convey "innovative" specialist knowledge along with experience.

The chirping of these birds in the cage is worthless and useless to me.
For as the crackling of thorns under the pot, so is the laughter of fools; that too is vanity.
As the saying goes, one "errs" forward.

A warm thank you to all who engage constructively, whereby constructive also allows criticism, that is for sure and I stand behind it.