Stone pool deck

Dear Maurizio, Sei Italiano? I live in Malta,in the meditteranean very close to Sicily and recently constructed an overflow pool with surrounding coping and floor tiles for the deck made from natural stone from Egypt. I have a big problem as mant tiles are remaining wet even after days of sunshine and underneath mortar is dry. I understand that stone is very porous but Greek supplier did not advise any waterproof treatment. Any help? Kevin Farrugia