My concrete slab floor is coated in a 10-12mm layer of a cork like material which I have since learned is called magnesite. apparently it was used in the 1960s to level concrete slabs and provide sound insulation.

It is very porous and I have read about the problems caused by it getting wet and reactions with the reinforcing in the concrete underneath etc. In fact it is so porous that if there is a lot of rain the magnesite absorbs moisture from the air, you can almost see the magnesite changing colour as it absorbs the moisture and gets almost damp.

I was wondering if I should seal the magnesite with Bondcrete to help prevent this? Later I will be laying a floating laminate floor over the magnesite. I may also need to level the magnesite prior to laying the floating floor with a strong cement/sand mix or self levelling cement and I was thinking that the Bondcrete would be good to have not only to seal the floor from any future spills or the humidity in the air, but also to help the cement-sand mix or self levelling cement stick to the magnesite better.

Thanks for any advice.


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