Gypsum compositions with enhanced resistance to permanent deformation comprisng organic polyphosphonic compounds and/or a borate comprinsing ulexite or colemanite

摘要

A set gypsum-containing composition comprises an interlocking matrix of the set gypsum formed from at least calcined gypsum, water and an enhancing material. The enhancing material comprises (i) an organic polyphosphonic compound or a mixture of polyphosphonic compounds or (ii) a borate comprising ulexite, colemanite or mixtures thereof, or a mixture of (i) and (ii). Also described is a set gypsum-containing composition wherein the set gypsum is treated with a mixture of a liquid and an enhancing material comprisng (i) an organic polyphosphonic compound or a mixture of polyphosphonic compounds, (ii) a borate comprising ulexite, colemanite or mixtures thereof (iii) a carboxylic compound or mixture of carboxylic compounds; or a mixture of (i), (ii) and (iii). A gypsum board may comprise the compositions described. An accelerator for an aqueous calcined gypsum composition comprises a borate and an accelerator material, preferably the accelerator material is calcium sulfate dihydrate.