grout wearing away to the touch

Vegas

I'm in Vegas - thought I knew what I was doing.
We grouted a ceramic tile floor to concrete slab.
Used satillo grout for 1/4 " joints.
Covered it with plastic, kept it temperature neutral.

I can scrape it up by rubbing my finger along the groutline and the paths the dogs take every day are obvious canyons.

What the heck did I do?

1/4", I tell ya!
Don't tell me saltillo grout ain't good for that (unless you feel you really have to).

My question now is -

Can I redo the low areas and maybe seal it all with a silicone sealer or something that'll strengthen what's there?
We've pulled and replaced the grout completely - TWICE!

I just wanna move into a tent!

ccarlisle

I think 'saltillo grout' is only meant for larger grout widths because of the coarse sand they use in it. Here, there's probably not enough cement in your grout to hold it together...

Another thought: was the tile pre-sealed? if not, the water in the grout mixture was absorbed by the tile...