燒石膏と人造樹脂とによる型成物の究研 (第2報)

概要

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In continuing the previous study (Report I), were reported in the present paper the result of studies on moulded test pieces from calcined gypsum plaster and artificial resin, in various points, as following: (1) Three samples of calcined gypsum plaster, (a) from natural crystal gypsum, (b) from mixture of natural crystal gypsum and synthesized crystal gypsum, from powder of limestone and sulphuric acid, in proportion of 50:50, and (c) from special gypsum plaster obtained by the hydrothermal heating under pressure of about 2kg/cm2 and about 123°C, (2) Urea-formaldehyde resin was used in water solution of various concentration 5-50%, (3) Various hardening agents of inorganic salt, as NH4Cl, NH4NO3, or (NH4)2SO4, were used for their hardening effect at the room temperature, (4) Compressive strengh and Ludwiks hardeness were tested after aging for various hours or days from 3 hours to 28 days, and (5) The largest values of compressive strength and Ludwiks hardeness were obtained by the special gypsum plaster calcined by the hydrothermal heating under pressure (about 2kg/cm2 and about 123°C).
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