I have a wet soil smell coming from the living room concrete slab. I had to remove all the tile in the leaving room. A remediation company came, they removed the drywall and dehumidified the place, without any success. We still smell the same things when it’s cold outside. There is no trace of water on the concrete whatsoever. The living room is on the north-east side of the house. Thanks
It sounds like moisture under the slab. Have you tapped a pice of plastic down to the slab for 24 hours? Taping a trash bad down then remove it the next day if the bag has water droplets on it or the area is wet under the bag the slab has moisture under it that is weeping up through the concrete. I have good luck sealing these floors in summer when the water table and possibly a spring are not causing the problem, in winter the moisture coming through will prevent the epoxy coatings I have used from sealing. I have fixed several homes with this problem by acid etching the slab and applying 2 part epoxy, it has worked well for me and may solve your problem.
It definitely sounds like water, and as @EdBeal correctly says you can seal it, which is a good idea. I would also suggest looking at how the water is getting there and ways you can stop it, because it could over time cause damp problems in the rest of your house. Look for areas where water is collecting against your house, and look at raising the ground level if you need to in order to get water to flow away. Check for pipe leaks as well.