I'd kill for a concrete floor. My listening space is in an old room build in the 1890s and the floor is a little bouncy. I had my speakers on spikes but they basically turned the whole floor into a passive radiator. The house literally shook. I tried Gaia and while they did not help with the bass problem they really focused the midrange. I now have my speakers on 3" thick granite blocks which did help the bass problem built I also left the Gaia on. Things sound very focused.
Your concrete floor is great cause it's totally inert. Coupling to that with spikes should be very effective but Gaia may help bring some mids and highs into focus by stabilizing the speaker overall