Denki Kagaku Kogyo Kabushiki Kaisha

Kuraray Co., Ltd.

Mitsubishi Cable Industries, Ltd.

Denka Company Limited

Takayuki Higuchi

Minoru Morioka

Yasuhiro Nakashima

Taiichiro Mori

Kenji Yamamoto

Yasutaka Ohshima

Isamu Hirano

Mitsuo Takahashi

Ryoetsu Yoshino

Yoshikazu Tanaka

Shinji Yamaguchi

Yukifumi Machida

Masaki Daimon

Shinya Inada

Shigeru Tomioka

Yoshihiro Iwasaki

Saburo Hada

Yoshinori Hitomi

Hiroyuki Ohashi

Tsutomu Kida

Kazuto Tabara

Katsuaki Iriuchijima

Etuo Sakai

Hiroaki Noritake

Makoto Shoji

Hideaki Ishida

Phuong Duc Nguyen

Kazuhide Iwanami

Masataka Ushiro

Provided is a fiber-reinforced carbonated hydraulic inorganic molded plate having a high bulk specific gravity, a high flexural strength, and a small dimensional change rate per specific gravity. (1) A fiber-reinforced carbonated hydraulic inorganic molded plate including: a cement component, a pulp, and a reinforcing fiber having an aspect ratio in a range of 40 to 1000; and being a carbonation-cured molded plate. (2) A molded plate being a cured product of a composition including at least a cement component, a pulp, and a reinforcing fiber, wherein the molded plate is a fiber-reinforced carbonated hydraulic inorganic molded plate and has a carbonation reaction rate of higher than or equal to 30%.

Fiber-reinforced carbonated hydraulic inorganic molded plate and method for producing same

The invention provides a cement admixture that improves the ability of concrete to bring about high initial strength, works in favor of enhancing the effect on hexavalent chromium reductions, and is less likely to decrease in the effect on hexavalent chromium reductions even upon storage as well as a method for reducing hexavalent chromium. The invention is embodied as (1) A cement admixture, characterized by comprising an expanding material containing free lime, a hydraulic compound and calcium sulfate anhydrite, and a tin sulfate-containing substance; (2) The cement admixture according to (1), characterized in that the tin sulfate-containing substance is contained in an amount of 0.2 to 8 parts by mass&#x2014;as calculated on a tin sulfate basis&#x2014;in a total of 100 parts by mass of the expanding material and the tin sulfate-containing substance; (3) The cement admixture according to (1) or (2), characterized in that the expanding material has been treated with carbon dioxide gas to form calcium carbonate therein; (4) The cement admixture according to any one of (1) to (3), characterized in that the expanding material has been surface treated with a shrinkage reducer; (5) A cement composition, characterized by containing cement, and the cement admixture according to any one of (1) to (4); and (6) A method for reducing hexavalent chromium, characterized by use of the cement composition according to (5).

Cement admixture and cement composition

The invention provides an expansive material that allows for large expansion of concrete at a material age of 2 to 7 days after pouring and permits concrete to have higher initial compressive strength and makes sure good storage stability, and a process for preparing that expansive material. The invention provides an expansive material and a process for preparing that expansive material, characterized in that clinker or pulverized clinker containing free lime, a hydraulic compound and calcium sulfate anhydrite is heat treated in a carbon dioxide gas atmosphere to form calcium carbonate in it. Preferably, the expansive material contains a particle in which the free lime, hydraulic compound, calcium sulfate anhydrite and calcium carbonate are all present; the content of calcium carbonate is 0.5 to 10% by mass; and the expansive material has a Blaine's specific surface area of 1,500 to 90,000 cm/g. The expansive material is blended with cement into a cement composition. The preparation conditions are preferably a carbon dioxide gas flow rate of 0.01 to 0.1 L/min. and a temperature of 200 to 800&#xb0; C., under which conditions there is calcium carbonate formed.

Expansive material and its preparation process

It is the object of the invention to provide a cement admixture, and a cement composition that can impart good enough rustproofness to reinforcing bars in hardened cement concrete, and can have resistance to penetration of chloride ions entering from the outside, prevent the hardened cement concrete from getting porous due to reduced leaching of Ca ions and have a self-recovery capability. The invention provides a cement admixture characterized by containing a calcium ferroaluminate compound comprising a CaO&#x2014;AlO&#x2014;FeOsystem, and having a FeOcontent of 0.5 to 15% by mass and a CaO.2AlOstructure with a CaO/AlOmolar ratio ranging from 0.15 to 0.7. It is preferable that the fineness is 2,000 to 7,000 cm2/g as represented in terms of the Blaine's specific surface area value; the potentially hydraulic substance and/or pozzolan substance (pozzolan substance or the like) is also used; the pozzolan substance or the like contains one or two or more selected from the group consisting of finely pulverized, quenched, granulated blast-furnace slag, fly ash, silica fume, metakaolin, incinerated pulp sludge ash, incinerated sewage sludge ash, and waste glass powder; and the blending proportion of the calcium ferroaluminate compound to the pozzolan substance or the like ranges from 10/1 to 1/10 by mass. The invention also provides a cement composition containing cement and the cement admixture.

Calcium ferroaluminate compound, cement admixture and its manufacturing methods, and cement composition

A process for producing the alumina fiber aggregate which, when examined by the electron microscope method, gives a frequency distribution regarding number of fibers, wherein the number of fibers having a fiber length of 50-200 &#x3bc;m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 &#x3bc;m is 30% or less (including 0), the number of fibers of 50-100 &#x3bc;m is 30-50%, the number of fibers longer than 100 &#x3bc;m but not longer than 200 &#x3bc;m is 30-50%, and the number of fibers longer than 200 &#x3bc;m is 20% or less (including 0). The process including the steps of grinding cottony alumina-based fibers comprising 70-100% by mass of AlOand 0-30% by mass of SiOwhile applying a pressure of 0.1-20 MPa thereto and then classifying the ground fibers.

Alumina fiber aggregate, process for producing the same, and use thereof

An object of the invention is to provide an alumina fiber aggregate which, when used as a filler in various materials such as, e.g., resins, coating materials, metals, and ceramics, enables the mixtures to have reduced viscosity and thereby heightens the productivity of products containing alumina fibers, and which enables cured thermosetting resins to have a sufficiently heightened thermal conductivity. This alumina fiber aggregate, when examined by the electron microscope method, gives a frequency distribution regarding number of fibers, wherein the number of fibers having a fiber length of 50-200 &#x3bc;m is 70% or more (including 100%), the number of fibers having a fiber length smaller than 50 &#x3bc;m is 30% or less (including 0), the number of fibers of 50-100 &#x3bc;m is 30-50%, the number of fibers longer than 100 &#x3bc;m but not longer than 200 &#x3bc;m is 30-50%, and the number of fibers longer than 200 &#x3bc;m is 20% or less (including 0). The fibrous mass comprises 70-100% by mass of AlOand 0-30% by mass of SiO.

A cement admixture and a cement composition having a carbonation suppressing effect and a heat-of-hydration suppressing effect are provided. A cement admixture containing one or more non-hydraulic compounds selected from the group consisting of &#x3b3;-2CaO.SiO, &#x3b1;-CaO.SiOand calcium magnesium silicate, a cement composition containing said admixture, and a carbonation suppressing method by use of said cement admixture or cement composition. According to the present invention, a remarkable carbonation suppressing effect can be obtained particularly when used in portland blast-furnace slag cement. This leads to an effective use of steelmaking slag and the like, and the load of clinker can be reduced, so that a cement composition of a low environmental load type can be attained. Further, this is suitable for cements in conformity with the EN standards, which are used in civil engineering and building industries.

Cement admixture, cement composition, and method for suppressing carbonation using the same

A cement admixture of a low environmental load type, capable of reducing hexavalent chromium, having a small slump loss or heat of hydration, hardly neutralized and capable of suppressing autogenous shrinkage to a low level; a cement composition; and cement concrete employing it, are presented. The cement admixture comprises a slowly cooled slag powder which contains melilite as the main component and which has a carbon dioxide absorption of at least 2%, has a COabsorption of at least 2%, has a loss on ignition of at most 5%, contains at least 0.5% of sulfur present as non-sulfuric acid form sulfur and/or has a concentration of non-sulfuric acid form sulfur to elute, of at least 100 mg/l, and further, preferably, has a degree of vitrification of at most 30%, a melilite lattice constant a of from 7.73 to 7.82 and/or a Blaine specific surface area of at least 4,000 cm/g.

Cement admixture, cement composition, and cement concrete made therefrom

Upon releasing a locking arm from a connecting terminal by inserting a jig through a front holder, the jig could not be erroneously inserted into a terminal inserting hole. Connecting terminals are inserted into a housing, and the connecting terminals are prevented from being pulled out of the housing backwardly by means of locking arms arranged above the respective connecting terminals. The front holder is engaged with the housing by a clamping mechanism in an axial direction and is movable laterally in a direction perpendicular to the axial direction. A pair of terminal inserting holes and an arm operating holeprovided for respective connecting terminals are shifted laterally. In a first position of the front holder, the terminal inserting hole is aligned with an axial line of a female-type connecting terminal, but the arm operating hole is shifted laterally from the locking arm.

Electrical connector

A cement composition of an environmental impact reducing type, used in the field of civil engineering and construction, which provides initial strength-development equal to that of ordinary Portland cement and which can reduce the clinker calcination amount, is provided. A cement composition containing Portland cement having a 3CaO.SiOcontent of at least 60% and a slowly cooled blast furnace slag powder, wherein the content of the slowly cooled blast furnace slag powder is from 10 to 50 parts per 100 parts of the cement composition.

Cement composition

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Itoigawa, Japan

Takayuki Higuchi