Onoda Cement Co., Ltd.

Japanese National Railways

Nichireki Chemical Industry Company Limited

Hajime Kato

Hiroshi Uchikawa

Yutaka Harada

Hiroshi Ucikawa

Akira Itoh

Noriyuki Itai

Katutoshi Sato

The specification discloses a self-hardening mold sand having surface stability and high compressive strength yet containing a comparatively small amount of water. The mold sand is prepared by mixing a self-hardening binder of clinker powder, containing 11CaO.7Al.sub.2 O.sub.3. CaX.sub.2 (where X is a halogen atom) and a sulphate, with a binder additive consisting of a surface active agent of which the main component is .beta.-naphthalene-sulphonic acid formaldehyde condensate salt, and then mixing this binder and binder additive with sand, water and preferably a retarder consisting of an organic carboxylic acid or boric acid.

Self-hardening mold sand

This invention relates to mixtures of molding sand which comprise a mixture of a molding sand with a rapid hardening cement containing calcium aluminate as amorphous glass and/or crystals, and/or calcium haloaluminate, a polymer water holding agent and a lime, or mixture of a molding sand with the above-mentioned rapid hardening cement, a polymer water reducing agent, a lime, and, if necessary, a foaming agent, and in either case with water. The mixture also provides a method of mixing the ingredients except for water and then kneading the mixture with water.

Molding sand mixtures

This invention relates to a super rapid hardening mixture comprising

Super rapid hardening mixture

This invention relates to a method for retarding the setting time of rapid hardening cement which comprises adding a boric compound to cement manufactured by adding insoluble anhydrite to clinker powder containing 11CaO.7Al.sub.2 O.sub.3.CaX.sub.2 or adding the clinker to insoluble anhydrite and intergrinding the mixture, and a method for still more retarding the setting time of rapid hardening cement which comprises adding a boric compound to cement containing a set-retarding agent other than the boric compound.

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Yokohama, Japan

Hajime Kato