Epoxy mortar is simply sand plus epoxy adhesive. Unlike cement mortar it has enough strength in tension to be used in very thin layers where needed. Its normally used
- to repair cementwork, where the applied mortar layer is too thin for cement to work
- as grout with paving, where it gives good weed resistance
A classic newbie error is to thin this expensive product with sand. This casuses early failure, epoxy mortar doesn't contain any more of the epoxy than is needed.