| 摘要 |
PROBLEM TO BE SOLVED: To prevent dropping of cement concrete from a sprayed face just after quick setting cement concrete is sprayed and to decrease the rebound rate and dust amt. by incorporating calcium aluminate having a specified vitrification rate, aluminum sulfate and alkali metal sulfates. SOLUTION: The calcium aluminate used has >=40% vitrification rate. It is a compd. essentially comprising CaO and Al2O3 obtd. by mixing a source material containing calcia and a source material containing alumina and heat treating the mixture by calcination in a kiln or melting in an electric furnace, and the CaO and/or Al2O3 is partly substituted with alkali metal oxides, silicon oxide, titanium oxide, iron oxide or the like. An accelerator slurry is prepared by incorporating water into the above-mentioned accelerator, and an accelerator slurry prepared by further incorporating naphthalenesulfonic acid-formalin condensation product is preferable. |
