I have a "T" shaped home built in the mid-fifties, with a walk-out basement. One of the legs of the "T" is finished into a nice room. It looks to have been mostly done when the home was built, with only some paneling added later.
One of the walls in the room is one-third underground outside. Inside, that same wall has two vents running down each end of the wall, running from the ceiling down to the floor. These were originally boxed in, framed with 2X4ís, with a gypsum and plaster covering. The wall, in the middle, was not framed or plastered, so the cinder blocks were left exposed to the room. When you looked at the wall, each end projects into the room about 4", for a length of 24".
Apparently while the home was being built, this ducting and corresponding framing and covering was done before the concrete floor was poured. While pulling down the paneling, I noticed the framing was loose at the bottom, and some investigating showed that most of the bottoms of the 2X4ís had rotted away. After removing all of the wood and gypsum, I can see that the framing originally went about 6" below the top of the concrete floor, forming a 4" by 24" long pocket, 6" deep. This must be below the slab, as it is wet at the bottom (just rained). The home has no sump pump, and the basement has never (to my knowledge) ever had a water problem. None of the cinder blocks show any sign of seepage, even in the pocket. Whatever moisture that ends up in the pocket has never filled up and spilled into the room. The basement has also never had any moisture related odor, except in the pockets.
But what to do? I do not want to ignore this. My plan was to just mix up a bag of redi-crete, and fill the pockets up to the top of the slab. Would this work? Or would I cause the moisture to now come into the room?