セメントに添加される石膏の適正な形態と量

概要

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In the course of industrial grinding, gypsum contained in cement is generally inverted to hemihydrate which sometimes causes to the false setting and other defects, while proper content of SO3 improves the properties of hardened cement mortars, ie, strength, shrinkage and chemical resistivity. Therefore this research aimed to minimize the amount of gypsum within the scope that the normal initial setting would just take place, and at the same time, to make a further addition of insoluble anhydrite such as calcined gypsum, natural or byproduct anhydrite up to the optimum SO3 content. Those results are summarised as follows:(1) The determination of SO3 concentration of extracted solution and the strength test led a conclusion that, for a normal portland cement of some Co., the optimum amount of SO3 should be nearly 2-3%, regardless of the modification of gypsum, though its amount of SO3 has been kept as 1.1-1.5% according to the current practice in this country.(2) In order to still more improve the quality of a sample of commercial rapid hardening portland cement, further addition of insoluble anhydrite was advisable, because its amount of SO3 seemed to be rather small.(3) The extraction test to infere the optimum SO3 content was likely to be successfully applied to the case of portland blastfurnace cement, as well as to portland cement.
公益社団法人日本セラミックス協会の論文