What kind of drill/mixer and paddle/blade should I use to barrel mix the Durock™ Self-Leveling Underlayment product?
The drill/mixer must have sufficient torque to move the volume of product in your batch. Typically a heavy-duty drill with capacity of 650 or higher RPM will be sufficient.
The paddle/blade will also have a big impact on the mixing energy introduced into the batch. USG recommends paddle type mixers (mixing paddle type 2, 3, 4, 8, or 9 – as outlined in the Technical Guidelines, prepared by the International Concrete Repair Institute, Pictorial Atlas of Concrete Repair Material Mixing Equipment (Guideline No. 320.5-2012)).