Abstract
It was proved that the property of supersulfated metallurgical cements has a great difference between adding natural-gypsum and adding calcined-gypsum.
Then, in order to know the influence of calcined-gypsum on properties of cement, they measured the change of the solubility of gypsum due to calcining and of properties of the cement due to calcining additional gypsum.
Those results were as follows:
(1) The cement produced by grinding together 80 to 85% fine ground slag, 10% gypsum calcined at 500 to 900°C and 5 to 10% calcined-dolomite or portland cement clinker has deueloped much higher mechanical strength than it of high early strength portland cement.
(2) If granulated slag is the product obtained by chilling it rapidly and thoroughly as it emerges from the blast furnace, it needs not necessarily over 45% lime content in it as the cement use.
(3) β-CaSO4, hard-gypsum calcined at a temperature about 600 to 900°C, is the most suitable modification as additional gypsum of the cement.
(4) It is desirable as additional gypsum of the cement that the solubility in water is very low at first and then gradually increases up to the normal value.
