JPH03205332A - Cement admixture - Google Patents

Abstract

PURPOSE:To provide an admixture showing preventing effects on reduction of high fluidity even with a small amount of addition, comprising Al, iron or zinc salt of copolymer of 2-4C olefin and maleic anhydride. CONSTITUTION:This cement admixture comprises one or more of Al salt, iron salt and zinc salt of a copolymer of 2-4C olefin and maleic anhydride. For example, the cement admixture consists of a blend of the salt (B for short) and one or a mixture (A for short) selected from naphthalenesulfonic acid- formalin condensate salt, melamine resin sulfonate, lignin sulfonate and a water- soluble salt of copolymer of 2-10C olefin and maleic anhydride. The blending ratio is preferably 5 pts. wt. component B based on 100 pts.wt. component A. This admixture is useful when used in a cement blend because reduction of fluidity with time is extremely low.

Description

[Detailed description of the invention] Industrial application field> The present invention relates to a cement admixture, and more specifically, a cement admixture that causes a small decrease in fluidity over time of cement paste, mortar, or concrete that is a cement compound. Regarding.

Prior art> In order to improve the workability of cement paste, mortar, or concrete, which is a cement mixture, it is necessary that the initial fluidity of the cement mixture is high and that the change in fluidity over time is small. .

It is known that fluidity decreases over time mainly due to the permanent reaction between cement and water and physical aggregation between the mixture.

Cement paste, mortar, or concrete, which are cement compounds, suffers from a hydration reaction between cement and water, which causes physical and chemical aggregation of cement particles over time after mixing, resulting in decreased fluidity and poor workability. Workability deteriorates over time. This phenomenon is generally called mortar flow reduction or concrete slump loss, and limits the pot life of the concrete.

In the case of ready-mixed concrete, concrete slump loss causes problems such as limited transportation time, waiting time at the pouring site, quality deterioration due to temporary interruption of pump pumping, and poor construction.

Furthermore, in the case of secondary concrete products, slump loss of concrete causes limitations in molding time and poor centrifugal compaction.

Therefore, cement paste, which is a cement formulation,
Slump loss, the decline in fluidity of mortar or concrete over time, is an important problem to be solved.

Problems to be Solved by the Invention For this reason, several methods have been conventionally considered as measures to prevent slump loss in concrete.

(1) Japanese Patent Publication No. 5856/1983 describes concrete materials selected from conventionally known water-soluble salts of sulfonated aromatic compounds or water-soluble salts of formalin condensates of sulfonated aromatic compounds. A method has been disclosed in which fluidity is maintained for a long time by repeatedly adding an admixture. Although this method is effective to some extent, it is time-consuming to add, not only is workability poor, but it is also economically unsatisfactory. It is also disadvantageous.

(2) JP-A No. 54-139929 discloses that a concrete admixture such as a naphthalene sulfonic acid formalin condensate is granulated and added to concrete, etc., and the granular admixture is gradually dissolved to cause slump. A method to prevent losses is shown.

Although this method can prevent slump loss to some extent, it is difficult to control the dissolution rate of the admixture;
If some parts remain in the concrete, the strength and durability of the concrete will decrease.

(3) Japanese Unexamined Patent Publication No. 60-1 6850 has c2 to C4.
Water-soluble salts of copolymers of olefins and ethylenically unsaturated dicarboxylic acids, and Japanese Patent Publication No. 63-10107 disclose additives consisting of saponified products of styrene and maleic anhydride copolymers. , does not show sufficient effect in preventing fluidity from decreasing over time. In addition, if the amount added to the cement mixture is increased in order to maintain fluidity for a long time, the curing time will be significantly delayed and the initial strength will be reduced.

(4) 02 to C6 in JP-A No. 60-1 6851
A method of preventing fluidity from decreasing over time using a copolymer (anhydride) of an olefin and an ethylenically unsaturated dicarboxylic acid has been proposed.

This is because the copolymer (anhydride) is insoluble in water and does not immediately show solubility when added to cement formulations.
As the hydration reaction of cement progresses, the cement mixture becomes strongly alkaline, and the copolymer (anhydride) is gradually hydrolyzed by the alkali and becomes water-soluble, thereby maintaining the fluidity of the cement mixture for a long time. be.

However, since these copolymers (anhydrides) have good stability against alkalis, they are difficult to undergo hydrolysis in the normal particle size range, and are not sufficiently effective in preventing fluidity from decreasing over time. In order to speed up the process, it is necessary to make the copolymer (anhydride) into fine particles. However, it is difficult to stably produce these fine particles industrially.

As described above, none of the conventional methods for preventing slump loss is sufficient.

An object of the present invention is to solve the problems of the above-mentioned conventional techniques and to provide a new cement admixture in which the fluidity of a cement mixture decreases little over time.

Means for Solving the Problems> As a result of intensive studies to solve the above problems, the present inventors have found that the alkaline content of a copolymer of a water-insoluble olefin having 2 to 4 carbon atoms and maleic anhydride has been determined. It has been found that by using a nium salt, a copper salt, a zinc salt, or a mixed salt thereof, even if a small amount is added within an industrially adjustable particle size range, a high effect of preventing the fluidity from decreasing over time is exhibited.

That is, in order to achieve the above object, according to the first aspect of the present invention, from the group consisting of aluminum salts, copper salts and zinc salts of copolymers of olefins having 2 to 4 carbon atoms and maleic anhydride. A cement admixture containing at least one selected is provided.

Further, according to the second aspect of the present invention, the following (A) 5
There is provided a cement admixture containing (B) Ia and (B) Ia.

(A) One type or 2f selected from naphthalene sulfonic acid formalin condensate salt, melasma resin sulfonate, lignin sulfonate, and water-soluble salt of a copolymer of a carbon a2-10 olefin and maleic anhydride. ! At least one component (B) selected from the group consisting of an aluminum salt, a copper salt, and a zinc salt of a copolymer of an olefin having 2 to 4 carbon atoms and maleic anhydride in the above mixture (B) is ) is preferably 5 parts by weight or more per 100 parts by weight of component.

The present invention will be explained in more detail below.

Specific examples of olefins having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, isobutene, and mixtures thereof.

In the copolymer (anhydride) of the olefin and maleic anhydride, the molar ratio of the olefin having 2 to 4 carbon atoms to maleic anhydride is preferably in the range of 271 to 2/3. this is,
If the molar ratio exceeds 2/1 and the amount of maleic anhydride is small, no significant effect on reducing changes in fluidity over time may be obtained, and if an excess of maleic anhydride with a molar ratio of less than 2/3 is used. This is because no particular effect can be obtained and it is not economical.

The number average molecular weight of the copolymer (anhydride) is 500.20
A range of 000 is preferred. Note that this number average molecular weight is expressed based on boristyrene based on gel perfusion chromatography.

Rather than using the copolymer (anhydride) as it is,
Used as water-insoluble aluminum salts, copper salts, zinc salts, or mixed salts thereof.

Any method may be used for producing the above copolymer, but
For example, isobutylene and maleic anhydride are radically polymerized in the presence of azobisisobutyronitrile using a radical initiator to form an isobutylene-maleic anhydride copolymer (anhydride), which is then neutralized with sodium hydroxide and copolymerized. The sodium salt of the polymer is prepared, and aluminum nitrate is further added to obtain the aluminum-based salt of the isobutylene-maleic anhydride copolymer.

The aluminum salt, copper salt and zinc salt of the copolymer or their mixed salt CBr&min> can be used alone or as a naphthalene sulfonic acid formalin condensate salt, melamine resin sulfonate, lignin sulfonate. It may be used in combination with one or a mixture of two or more selected from acid salts and water-soluble salts of copolymers of olefins having 2 to 10 carbon atoms and maleic anhydride (component A). The blending ratio of both is (A) FIi. The amount of component (B) is preferably 5 parts by weight or more per 100 parts by weight. (B) If F& is less than 5 parts by weight, no significant effect on reducing changes in fluidity over time will be obtained.

The cement admixture of the present invention may be added to the kneading water of the cement mixture, or may be added to the thoroughly kneaded cement mixture.

Examples> The present invention will be specifically explained below based on Examples, but the present invention is not limited thereto.

(Example 1) The cement admixture of the present invention was evaluated by the following mortar test.k. Table 1 shows the composition of the mortar.

Aluminum salt of isoptylene-maleic anhydride copolymer for cement mixing (0.1% by weight to cement), commercially available naphthalene sulfonic acid formalin condensate salt (0.4% by weight in terms of solid content) Add cement), water and cement and mix for 30 seconds, then add sand while mixing.
Added for 0 seconds followed by mixing for 60 seconds. The mixture was allowed to stand for 20 seconds, the mortar adhering to the mixing bee and paddle was scraped off, and then mixed again for 120 seconds.

1 1 After filling the obtained mortar into a main Nislumb cone with a height of 15 cm, the mini slump cone was removed and the slump was measured and found to be 11.5 cm. Furthermore, after allowing the mortar to stand still for 60 minutes, the slump was measured in the same manner after being mixed for 1 minute, and the remaining slump rate (%) was calculated from the following formula: 90
．． It was 4%.

Slump residual rate (%) Slump value (after 0 minutes) (Example 2) Example except that copper salt of isobutylene-maleic anhydride copolymer was used instead of alkium salt of isobutylene-maleic anhydride copolymer A mortar test was conducted in the same manner as in 1, and the results are shown in Table 2.

(Example 3) A mortar test was conducted in the same manner as in Example 1, except that a zinc salt of an isobutylene-maleic anhydride copolymer was used instead of an aluminum salt of an isobutylene-maleic anhydride copolymer, and the results are shown in Table 2. It was shown to.

(Comparative Example 1) Isobutylene-maleic anhydride copolymer (
A mortar test was conducted in the same manner as in Example 1 except that anhydrous) was used, and the results are shown in Table 2.

(Comparative Example 2) A mortar test was conducted in the same manner as in Example 1, except that the sodium salt of isobutylene-maleic anhydride copolymer was used instead of the aluminum salt of isobutylene-maleic anhydride copolymer, and the results were It is shown in Table 2.

(Comparative Example 3) A mortar test was conducted in the same manner as in Example 1 except for using an aluminum salt of a styrene-maleic anhydride copolymer instead of an aluminum salt of an isobutylene-maleic anhydride copolymer, and the results were It is shown in Table 2.

1 2 (Comparative Example 4) A mortar test was conducted in the same manner as in Example 1 except that the alkium salt of the isobutylene-maleic anhydride copolymer was not used, and the results are shown in Table 2.

(Example 4) A mortar test was conducted in the same manner as in Example 1 except for the k point, except that the amount of the aluminum salt of the isoptylene-maleic anhydride copolymer was changed to 0.02 (11% by weight vs. cement), The results are shown in Table 2.

(Example 5) A mortar test was conducted in the same manner as in Example 1, except that only the aluminum salt of isobutylene-maleic anhydride copolymer (0.4% by weight vs. cement) was used, and the results are shown in Table 2. .

(Example 6) The cement admixture of the present invention was evaluated by the following concrete test.

Table 3 shows the mix composition of concrete.

The slump was measured according to JIS A1101.

Using a forced kneading chimiser (inner volume: 50 It), aluminum salt of isobutylene-maleic anhydride copolymer (0
．． After mixing for 2 minutes, commercially available naphthalene sulfonic acid formalin condensate salt (0.3% by weight relative to cement in terms of solid content), water, cement, fine aggregate, and coarse aggregate were mixed for 2 minutes, and then kneaded. The dough was put out onto a bat for turning and kneaded, and the slump was measured to be 20.7 cm. Furthermore, after the concrete was allowed to stand still, it was kneaded at predetermined intervals and the slump was measured, and the results are shown in FIG.

(Comparative Example 5) A concrete test was conducted in the same manner as in Example 6, except that only commercially available naphthalene sulfonic acid formalin condensate salt (0.5% by weight to cement in terms of solid content) was used, and the results were It is shown in Figure 1.

Table 1 Cement mix for mortar: Ordinary Boltland cement (manufactured by Mitsubishi Mining Cement) Sand: From Sakuragawa, Ibaraki Prefecture (FM = 2. Water: Well water 19) Table 3 Cement mix for concrete: Ordinary Boltland cement (Mitsubishi Mining Cement) fine aggregate: mixed sand (coarse sand/fine sand = 8/2 (weight ratio)
, specific gravity 2.56, FM = 2.83) Coarse sand: from Nakagawa, Ibaraki Prefecture (specific gravity 2.54, FM = 3.10) Fine sand from Mandano, Ichihara City, Chiba Prefecture (specific gravity 2.62, FM 1.78) Coarse aggregate: Produced in Tanigawa-cho, Aso-gun, Tochimoto Prefecture (ratio 1i2.72) 18 Effect of the invention> The novel cement admixture of the present invention reduces fluidity over time when used in cement mixtures. Because of its small size, it is useful as an additive to cement mixtures such as ready-mixed concrete.

[Brief explanation of drawings]

FIG. 1 is a graph showing an example of a concrete test using the cement admixture of the present invention.

Claims (3)

[Claims] (1) A cement admixture characterized by containing at least one selected from the group consisting of aluminum salt, copper salt, and zinc salt of a copolymer of an olefin having 2 to 4 carbon atoms and maleic anhydride. (2) A cement admixture containing the following components (A) and (B). (A) One or two selected from naphthalene sulfonic acid formalin condensate salt, melamine resin sulfonate, lignin sulfonate, and water-soluble salt of a copolymer of an olefin having 2 to 10 carbon atoms and maleic anhydride. The above mixture (B) at least one selected from the group consisting of aluminum salt, copper salt, and zinc salt of a copolymer of an olefin having 2 to 4 carbon atoms and maleic anhydride. (3) The cement admixture according to claim 2, wherein the component (B) is present in an amount of 5 parts by weight or more based on 100 parts by weight of the component (A).