Gypsum building materials for mfg. water resistant prods. - where lime marl is baked, then mixed with gypsum and baked

摘要

Clay silicate (I) contg. unsatd. lime cpds. is baked (B1) below its sintering temp., and mixed in a continuous process with 60-90, esp. 80% of CaSO4, 2 H2O, and subjected to a second baking treatment (B2). Material (I) pref. produces optimum water resistance and strength in the final mixt. which should only contain min. atms. of free CaO and tricalcium aluminate. Material (I) is pref. a lime marl contg. 56-74 esp. 65% CACO3, to which a ferritic material is added to minimise formation of harmful cpds. such as tricalcium aluminate; and baking (B1) is pref. at min. 800 degrees C. Either natural or synthetic gypsum may be used. Inexpensive materials can be used, e.g. gypsum obtd. in mfr. H3PO4 or in removing SOx from waste gases.