We had to replace the drain in our shower floor and need to replace the tiles that were removed. The tiles are 2" hexagon tiles and we have matching tiles. We had a handyman come out to replace the tiles but he used mastic that was not rated for shower floors and that all washed away. We went to our local home store and they suggested Gorilla Glue construction adhesive. The base is cement, the tiles are porcelain. We have an area that is about 1 foot square to replace. We are in a small town so no real "tile contractor" to come do the job, plus, it's an easy enough patch if we can find the right product. Thanks.