Cement additive

Details Cement additive Cement additive

2001-11-05

2004-07-13

Szekely, Peter (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S004000, C525S408000, C526S317100, C526S318000, C526S318300, C526S318400, C526S318410, C526S318500, C526S319000, C526S320000

Reexamination Certificate

active

06762220

ABSTRACT:

This invention relates to a cement additive and more particularly, to a cement additive used to improve the fluidity and appearance of strength of cement slurry, cement paste, mortar and concrete.
Various cement additives comprising polycarboxylic acid type copolymers have been proposed for enhancing the fluidity and flowability of concrete. While this works well for ordinary concretes, it is not so effective when high strength and high durability are required, as such copolymers tend to entrain an excess of air and retard setting.
In relation to pre-formed concrete products, it is strongly desired to decrease the total time spent in a form and to prevent defects when the form is removed. For such products, good appearance is also highly desirable, when the form is removed after steam curing. Various polycarboxylate materials to achieve this have been proposed, but none have been entirely satisfactory, causing such problems as retarded setting and low fluidity.
It has now been found that a cement additive containing a polycarboxylic acid type copolymer and a polyalkylene glycol derivative having a specific molecular structure can alleviate and sometimes completely remove all the above-mentioned problems, by having a high dispersing ability for various concretes, improving and retaining the fluidity of concrete, and also making it possible to increase the strength of pre-formed concrete, such that form removal after steam curing can be carried out relatively early, giving a product with low aeration.
The invention therefore provides a cement additive containing a polycarboxylic acid type copolymer and/or the salts thereof and a polyalkylene glycol derivative, said polycarboxylic acid type copolymer contains at least one species of copolymer, the monomers of which copolymer comprise at least an unsaturated polyalkylene glycol type monomer (A) and an unsaturated mono- or dicarboxylic acid type monomer (B).
The invention also relates to a cement additive, wherein the polycarboxylic acid type copolymers are copolymers which additionally include as monomer components an unsaturated polyalkylene glycol ester type monomer (C) and/or a monomer (D) polymerizable with the above-mentioned monomers (A) and (B), or with the monomers (A), (B) and (C).
The invention further relates to the above-mentioned cement additive, wherein the monomer (A) is a compound according to the general formula (1):
wherein R
1
, R
2
and R
3
are each independently hydrogen or methyl, provided that not all are methyl; R
4
is —CH
2
O—, —(CH
2
)
2
O—, —C(CH
3
)
2
O— or —O—; the total carbon number of R
1
, R
2
, R
3
and R
4
is 3; R
5
O is one or more species of C
2
-C
4
oxyalkylene groups, and in the case of two or more species may be block or random; R
6
is hydrogen or a C
1
-C
22
alkyl, phenyl or C
1
-C
18
alkylphenyl group; p is an integer from on average 1to 100;
the monomer (B) is a compound according to the general formula (2):
wherein R
7
and R
8
are each independently hydrogen or methyl; R
9
is hydrogen, methyl or —(CH
2
)
q
COOM
2
; R
10
is —(CH2)
r
—; q and r are each independently an integer from 0 to 2; M
1
and M
2
are a monovalent metal, a divalent metal, ammonium or an organic amine;
the monomer (C) is a compound according to the general formula (3):
wherein R
11
and R
12
are each independently hydrogen, methyl or (CH
2
)
u
COOM
3
, u is an integer from 0 to 2, M
3
is a monovalent metal, a divalent metal, ammonium or an organic amine; R
13
O is one or more species of C
1
-C
4
oxyalkylene groups, and in the case of two or more species may be block or random; R
14
is hydrogen or a C
1
-C
22
alkyl, phenyl or C
1
-C
22
alkylphenyl group; s is an integer from 0 to 2; t is an integer an average from 1 to 300; and
the monomer (D) is a compound according to the general formula (4):
wherein R
15
, R
16
, R
18
and R
19
are each independently hydrogen or methyl, provided that not all are methyl, R
17
O is one or more species of C
2
-C
4
oxyalkylene groups, and in the case of two or more species may be block or random; w is an integer an average from 1 to 300; v and x are each independently an integer from 0 to 2.
The invention also relates to the abovementioned cement additive, wherein the composition ratios of the monomers (A) and (B) in the polycarboxylic acid-type copolymers are 30-100 mole % based on the total mole amount of the monomers, and the average molecular weight of said polycarboxylic acid-type copolymer is from 3,000-100,000 (all molecular weights (MW referred to herein were measured by gel permeation chromatography with polyethylene glycol as standard).
The invention also relates to the abovementioned cement additive, wherein the average molecular weight of the polyalkylene glycol derivatives is from 1,000-100,000, in which the alkylene is one or more C
2
-C
4
species, and the terminal groups of the polyalkylene glycol is hydrogen or a C
1
-C
18
is alkyl or phenyl group.
Further, the invention relates to the abovementioned cement additive containing 100 weight parts of the polycarboxylic acid type copolymers and 10-50 weight parts of the polyalkylene glycol derivatives.
Also, the invention relates to the above mentioned cement additive, wherein the amount of the polycarboxylic acid type copolymers added to cement is 0.05-1.0% by weight based on the weight of cement, and the amount of the polyalkylene glycol derivative added to cement is 0.00-0.5% by weight based on the weight of cement.
Further, the invention relates to use of abovementioned cement additive in high strength concrete.
The invention also relates to the use of the abovementioned cement additive in the formation of pre-formed concrete articles by steam curing.
The invention further provides a method of preparation of a high-strength concrete mix, comprising the incorporation in the mix of a cement additive as hereinabove described.
The invention further provides a method of preparing of a concrete mix adapted to be used for the manufacture of articles by steam curing, comprising the incorporation in the mix of a cement additive as hereinabove described.
In a cement additive according to the invention, the monomers (A) are typically compounds according to the abovementioned general form (1), more specifically, the compounds in which 1-100 mole of an alkylene oxide is added to an unsaturated alcohol such as 3-methyl-2-buten-1-ol, 3-methyl-3-buten-1-ol, 2-methyl-3-buten-2-ol. One or more species of unsaturated alcohol may be used.
Examples of monomers (B) include compounds according to general formula (2), more specifically, for example, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid. One or more species of these may be used.
Monomers (C) are typically compounds according to general formula (3). Specific examples include unsaturated polyalkylene glycol monoester type monomers such as polyethylene glycol monoesters, polypropylene oxide monoesters, monoesters of polyethylene glycol/polypropylene oxide copolymers, derivatives in which a terminal hydrogen of these glycols is etherified, and the like, such as triethylene glycol monoacrylate, polyethylene glycol (MW 200) monoacrylate, polyethylene glycol (MW 400) monoacrylate, polyethylene glycol (MW 600) monoacrylate, polyethylene glycol (MW 1000) monoacrylate, polyethylene glycol (MW 2000) monoacrylate, polyethylene glycol (MW 4000) monoacrylate, polyethylene glycol (MW 6000) monoacrylate, triethylene glycol monomethacrylate, polythylene glycol (MW 200) monomethacrylate, polyethylene glycol (MW 400) monomethacrylate, polyethylene glycol (MW 600) monomethacrylate, polyethylene glycol (MW 1000) monomethacrylate, polyethylene glycol (MW 2000) monomethacrylate, polyethylene glycol (MW 4000) monomethacrylate and polyethylene glycol (MW 6000) monomethacrylate, and one or more species of these may be used.
The monomers (D) are typically compounds according to general formula (4), specific examples including unsaturated polyalkylene glycol diester type monomers and/or styrene, styrenesulfonic acid and/or the

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