concrete floors

There are 3 types of concrete sealant I have used in the past, one is water based and covers concrete quickly and easily and prevents the sort of "dusting" you get when you walk on an untreated floor. This has no ill effects on tiling.I have also used a very diluted PVA bond, diluted 5-10:1, this is a cheap way of doing it, won't last more than a few months but helps provide better adhesion for your tiles anyway.Then there is the paint you use on a garage floor. The most expensive option and probably not the best for tile adhesion.You should not really put tile adhesive straight onto a concrete floor anyway, it is better to seal it first as the tile adhesive will stick to the concrete better. If you don't seal it the tiles are more likely to rise as the top layer of the concrete is where the water has evaporated from and is less solid and prone to "dusting"If you are tiling within the next 4-6 months I'd do it with PVA which is available in most Bricos 

Sorry, I should have said before, try a dilution of 10:1 to start and see if it seals ok. If you use too strong a mix it can be quite tacky and you will sound like a cartoon character when you walk across the floor, if you have a paddle which you can put into a drill that would be a good way of mixing in a bucket as well (if you are lazy like me that is).