Continue chiseling down to the waterproofing.
How to make a shower floor for tile.
Use a 3 pound sledgehammer to hammer the tile until it s dislodged.
Mix in water and more concrete mix following the manufacturer s instructions until the result is the consistency of a milkshake.
Add only enough water to the dry mix to make a dry pack.
Slip a flatbar into that hole and under the mortar.
Remove the drain cover and place a clean towel or rag into the drain before chiseling along the grout line of the center.
The first is a single layer shower floor which can then be coated with redgard or a similar product or covered with kerdi to waterproof it.
If not you can make your own mix with 4 parts sand to 1 part portland cement.
Create the concrete mixture pour concrete mix into a bucket until it s about one third full.
Make the smooth surface of the tiles rougher to create more traction usually done by using an anti slip solution add anti slip treads or stickers cover the tile floor with non slip rugs switch to non slip floor tiles only recommended if you re planning a full renovation.
Use a spade handle drill which works like a giant hand mixer.