To obtain a compsn. which hardens under practical molding conditions and gives a hardened body excellent in compressive strength and bending strength without using water glass as a hardenable component by incorporating specified amts. of propylene carbonate and water into magnesium oxide.
Magnesium oxide preferably having 1-500 μm average particle diameter is prepd. preferably as a mixture of soft-burnt magnesium oxide having low bulk specific gravity with hard-burnt magnesium oxide having high bulk specific gravity, 1-60 pts.wt., preferably 1 to <5 pts.wt. or 5-40 pts.wt., especially preferably 1 to <5 pts.wt. or 5-20 pts.wt. propylene glycol and 20-135 pts.wt. water are incorporated into 100 pts.wt. of the magnesium oxide and 30-400 pts.wt. aggregate such as CaCO3 and 0.2-20 pts.wt. fibers such as glass fibers are further incorporated if necessary. Additives such as a defoaming agent, a blowing agent and a chemical admixture for cement may further be added by 0.01-30 pts.wt.
Inoue, Hiroshi
Yamamoto, Katsuhiko
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