| 摘要 |
PURPOSE:To improve the cement strength by changing the amount of a blended alkali carbonate and gypsum according to the ratio of an added hardening accelerator composed of a sintered compact of specific three kinds of minerals, the alkali carbonate and gypsum. CONSTITUTION:A sintered compact of three kinds of minerals is obtained by defining the blending composition of a CaO source (e.g. CaCO3), an Na2O source (e.g. Na2CO3), an Al2O3 source (e.g. Al2O3) and an SO3 source (e.g. gypsum) which are raw materials so as to provide the composition ranges of 10-75% 3CaO.2Na2O.5Al2O3, 1.8-13.2% Na2SO4 and 11.8-88.2% Na2O.Al2O3 and burning the resultant blend at >=1150 deg.C. Blending is carried out so as to provide the mixing ratio of an alkali carbonate (e.g. Na2CO3) to be blended therewith within the shadowed range surrounded with points (A) to (F) in Fig. I (the abscissa axis; the ratio of the added cement hardening accelerator, unit; %; the coordinate axis; the mixing ratio of the alkali carbonate to cement, unit; %) and the mixing ratio of the gypsum expressed in terms of CaSO4 within the shadowed range surrounded with points (a) to (i) in Fig II [the abscissa axis; same as that in Fig I; the coordinate axis; the ratio of CaSO4/(CaSO4 + sintered compact of the three kinds of minerals), unit; blending ratio]. Thereby the objective cement hardening accelerator is obtained. |
