Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Patent
1996-06-13
1998-01-13
Marcheschi, Michael
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
106725, 106724, 106727, 106728, 106808, 106809, 106810, 106823, 524 2, 524 5, 524650, 526240, 526286, 525291, 525293, C04B 2404, C04B 2416, C04B 2426
Patent
active
057074453
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present application is filed under 35 U.S.C. .sctn.271 of PCT/JP94/02097, filed on Dec. 14, 1994.
FIELD OF THE INVENTION
The present invention relates to an admixture for concrete. In particular, the present invention relates to an admixture for concrete which can impart proper fluidity to a hydraulic composition such as cement paste, mortar and concrete, and has an excellent effect on the retention of fluidity of the composition.
DESCRIPTION OF THE RELATED ART
Among various admixtures for concrete, representative examples of the admixture having a high fluidizing effect on a hydraulic composition include so-called high range water reducing agents such as salts of condensates of naphthalenesulfonic acid with formaldehyde (hereinafter referred to as "the naphthalene compounds"), salts of condensates of melaminesulfonic acid with formaldehyde (hereinafter referred to as "the melamine compounds"), and salts of polycarboxylic acids (hereinafter referred to as "the polycarboxylic acid compounds").
These admixtures have respective disadvantages, though they also exhibit excellent functions. For example, when the naphthalene or melamine compound is added to a hydraulic composition, the resulting composition is problematic in the retention of fluidity (hereinafter referred to as "slump loss"), though the composition is excellent in hardening characteristics, while the polycarboxylic acid compound has the problem of significantly retarding the hardening of the composition.
There has recently been developed another polycarboxylic acid compound which can impart a proper fluidity to concrete. Since this polycarboxylic acid admixture can exhibit an excellent dispersing effect even when used in a small amount, the amount of the admixture to be added can be reduced, which makes it possible to solve the above problem of retarding the hardening. Examples of the polycarboxylic acid compound include water-soluble vinyl copolymers such as copolymers comprising a polyalkylene glycol monoester monomer having an unsaturated bond and one or more members selected from among acrylic monomers and unsaturated dicarboxylic monomers (see Japanese Patent Publication-B No. 59-18338, published on Apr. 26, 1984).
It is presumed that the water-soluble vinyl copolymer having an oxyalkylene chain exhibits its dispersing effect by the mechanism such that the oxyalkylene chain, which constitutes a graft structure, of the copolymer sterically hinders the adhesion among particles.
However, the above problem of slump loss cannot be solved even when the above polycarboxylic acid having an oxyalkylene chain is used, so that great pains are still taken in controlling the quality of concrete over the whole period from the preparation thereof until the placement thereof through transportation.
The polyalkylene glycol monoester monomer having an unsaturated bond, which is disclosed in the above Japanese Patent Publication-B, has 1 to 100 of an oxyalkylene group(s) each having 2 to 4 carbon atoms. However, the above monomers specifically disclosed in the Referential Example of the above patent document are those prepared by adding ethylene oxide to the starting material thereof, wherein the number of ethylene oxide molecules added is at most 23. Further, the patent document is silent about a monomer prepared by adding more than 23 alkylene oxide molecules to the starting material thereof.
DISCLOSURE OF THE INVENTION
Summary of the Invention
The present inventors have made extensive studies on water-soluble vinyl copolymers having an oxyalkylene chain, and in particular, the relationship between the length of the oxyalkylene chain of a starting monomer and the performance of the copolymer prepared by the use of the monomer. As a result of the studies, they have found that when a copolymer prepared by the use of a monomer having a long oxyalkylene chain with its length being in a specific range (corresponding to a number of alkylene oxide molecules added of 110 to 300) is used as an admixture for concrete, the a
Fujita Shuichi
Kitagawa Kazushige
Satoh Haruyuki
Tanisho Yoshiaki
Yamato Fujio
Kao Corporation
Marcheschi Michael
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