Same as Keene’s cement.
Keene’s cement flooring cement, gypsum cement, hard-burnt plaster, tiling plaster
A hard, white, high-strength, quick-setting finishing plaster; takes a high polish; made by burning gypsum at a high temperature, grinding to a fine powder, and then adding alum (to accelerate the set).
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.