[Greenbuilding] Passive solar home--concrete overlay re thermal mass

[KTOT (g)]

I have a passive solar off-grid home that works fantastically with a 2 in. 
concrete slab that is finished with decorative concrete stain/paint. 
However, the slab and stain/sealer are completely defective and most likely 
have to be replaced, but one party is likely to propose simply putting a 
concrete overlay product atop the existing slab. This overlay product 
consists of two parts--1) Portland cement, aggregate, and a stain, and 2) a 
modified acrylic latex resin. My believe is this product is not good thermal 
mass (atop the concrete) as the resin component is synthetic or at best 
partly plant material. That in fact the entire slab needs to be removed and 
the floor rebuilt from scratch to resolve the serious problems and still 
provide me with optimal thermal mass.

Does anyone have experience or knowledge about this? Using or not using a 
concrete overlay product for the top layer of a floor for thermal mass, vs. 
a plain darkly stained concrete slab.