If not you can make your own mix with 4 parts sand to 1 part portland cement.
How to make a shower floor for tile.
Add only enough water to the dry mix to make a dry pack.
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.
Mix the substance in a wheelbarrow or mud pan.
Continue chiseling down to the waterproofing.
Use a 3 pound sledgehammer to hammer the tile until it s dislodged.
Use a spade handle drill which works like a giant hand mixer.
Remove the drain cover and place a clean towel or rag into the drain before chiseling along the grout line of the center.
Slip a flatbar into that hole and under the mortar.
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.
Here it is best to use premixed deck mud if it is available at your local home improvement store or tile shop.