material. And being that old it surely is porus. Since you found this wonderful product, you have a nice clean floor but unsealed.
YOu know those Chimineas around? If you buy one from a reputable dealer, he/she will recommend coating the entire exterior of the chiminea with a good quality floor wax in the liquid state. Since this is also very porus, the floor wax acts like a sealant and it does work. I looked out one day and the water was beading up on it. I do this every Spring.
There is something on the market that is like this floor wax but much better. It is a silicon sealer that is applied to the grout in between ceramic tile. The silicon is for the grout and is rendered useless to the ceramic tile because of its shiny non porus coatings.
But, in your case this would be a great BASE for you flooring. But, it is expensive and for such a big area, you would need about a gallon of the stuff. It sells for about $12 for a bottle the size of an olive container, maybe alittle larger. This would be only the BASE for our attack.
Next after this had dried, I would use the liquid floor wax to act as a polisher and coating also.
The test for the silicon is to apply one coat and let it dry then dabble a drop of water on the area and if it beads up, your set. Normally it takes two coats.
Please do not fall into the trap of someone suggesting that you seal the tile with Polyurethane or something like this. It will yellow, peel, and become your worst nightmare.
Go the silicon for a base, then use a good floor liquid wax as your maintenance.