Got a mates floor to do this weekend and he has recently had a new 3sqm concrete base laid in his utility room (that needs tiling), its VERY sandy so I want to seal it, can anyone recommend a sealant/impregnator ?

If it is very sandy it is either too weak or has been poorly cured. It may well not be suitable to tile directly onto.

I'm guessing as its only recently laid (and the house resembles a building site at the moment with all the work going on-hence more dust and dirt on it) that it will be fine, just need to seal it and see what its like after that.
Do bal make a sealant for concrete floors ?

bump................

How old is the screed and as Ajax says it could be too weak....primer will not act as a magic cure. Trust in Ajax, he is a professional in these sort of things.

It's 3 weeks old.

Its basically where they would have to step out (and down) into their out-house/pantry, so instead of having a step they have now leveled it (raising it up approx 4"), I looked at it the other day (whist the plasterer was mixing up, and a kitchen fitter and sparky working away) and it looked dusty and sandy to me (but this could be because of all the work going on).

I would rather just seal it as its such a small area, BUT if tomorrow when I can get in there properly I see its crumbling away I will have to tell them it needs hacking out and re-laying. (I don't think its that bad though).