A gypsum-based mortar for plastering is prepared from semi-hydrated gypsum, quartz sand, Ca(OH)2, powdered coal ash, slag, lime stone, hoolamite, volcanic dregs, haydite, polystyrene foam, expanded pearlite, zeolite, and ethene-vinyl acetate copolymer resin. Agypsum-based mortar for automatic leveling is prepared from semi- hydrated gypsum, quartz sand, Ca(OH)2, powdered coal ash, slag, lime stone, ethene-vinyl acetate copolymer resin, methyl hydroxyethyl (or hydroxypropyl) cellulose ether, sulfonated cyanuramide-formaldehyde resin and gluconate.