Vapor permeability improver for hardening body containing dicalcium silicate γ phase

Abstract

To develop a vapor permeability improver for improving vapor permeability of a hardening body containing dicalcium silicate γ phase.SOLUTION: A vapor permeability improver for a hardening body containing dicalcium silicate γ phase includes a basic organic acid aluminum. A vapor permeability improvement method is a method for improving vapor permeability of a hardening body containing dicalcium silicate γ phase, using a basic organic acid aluminum as a vapor permeability improver.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an air permeability improver for hardened bodies containing di-calcium silicate γ-phase. [Background technology]

[0002] Dicalcium silicate γ-phase has attracted attention as a material useful for fixing carbon dioxide in hardened bodies such as cement concrete (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-22383 A Summary of the Invention [Problem to be solved by the invention]

[0004] To fix carbon dioxide, it is preferable that the cured material is porous. The degree of porosity can be evaluated by measuring the air permeability.

[0005] An object of the present invention is to develop an air permeability enhancer for improving the air permeability of a hardened material containing a γ-phase di-calcium silicate. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that the use of a basic organic aluminum salt can improve the air permeability of a hardened body containing a di-calcium silicate γ phase, and have completed the present invention based on this finding.

[0007] The present invention is as follows. [1] An air permeability improver for hardened bodies containing di-calcium silicate gamma phase, which contains a basic organic aluminum salt. [2] A method for improving the air permeability of a hardened material containing di-calcium silicate gamma phase, using a basic organic aluminum salt as an air permeability enhancer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will be described in detail below based on preferred embodiments, but the present invention is not limited to the following embodiments and various modifications are possible within the scope of the claims. In the present invention, the expression "numeric value 1 to numerical value 2" in relation to a numerical range means a numerical range including both the numerical values ​​1 and 2, with numerical value 1 being the lower limit and numerical value 2 being the upper limit, and is synonymous with "numerical value 1 or more and numerical value 2 or less."

[0009] The present invention relates to an air permeability improver for a hardened body containing a γ-phase di-calcium silicate, which contains a basic organic aluminum salt (hereinafter referred to as "the air permeability improver of the present invention").

[0010] A basic aluminum organic acid salt is an aluminum organic acid salt having basicity. The basicity is defined as {(the number of chemical equivalents of aluminum in a certain amount of compound)-(the number of chemical equivalents of organic acid in a certain amount of compound)} / (the number of chemical equivalents of aluminum in a certain amount of compound)×100(%). For example, in the case of basic aluminum succinate in which the organic acid is succinic acid, when 4.6 g of aluminum and 15 g of succinic acid are contained, the basicity is {(4.6 / 27)×3-(15 / 118)×2} / {(4.6 / 27)×3}×100=50.3%.

[0011] Preferred examples of organic acids constituting basic organic acid aluminum include monocarboxylic acids, dicarboxylic acids, oxycarboxylic acids, etc. Examples of monocarboxylic acids include formic acid, acetic acid, propionic acid, n-butyric acid, valeric acid, etc. Examples of dicarboxylic acids include oxalic acid, succinic acid, maleic acid, malonic acid, phthalic acid, glutaric acid, etc. Examples of oxycarboxylic acids include glycolic acid, lactic acid, tartaric acid, malic acid, citric acid, etc. Among these, oxycarboxylic acids are preferred, and among oxycarboxylic acids, glycolic acid, lactic acid, and malic acid are preferred. Particularly preferred is lactic acid, and a combination of lactic acid and an oxycarboxylic acid other than lactic acid may also be used.

[0012] One example of a method for producing basic organic aluminum salt is a method in which a soluble aluminum salt such as aluminum chloride, aluminum sulfate, basic aluminum chloride, or aluminum nitrate is reacted with an alkali metal or ammonium carbonate or bicarbonate, and the precipitated alumina hydrate is dissolved in an organic acid. Another example is a method in which an alkali aluminate is reacted with carbon dioxide gas, and the precipitated alumina hydrate is dissolved in an organic acid.

[0013] The air permeability improver of the present invention preferably comprises a basic organic aluminum salt, but may contain other compounds to the extent that the function of improving air permeability is not impaired.

[0014] A good example of a hardened body is cement concrete. Cement concrete is made by mixing and hardening cement, water, aggregate, and optionally adding admixtures.

[0015] Examples of cement include Portland cement, blended cement, etc. Examples of Portland cement include normal Portland cement, high-early-strength Portland cement, extra-high-early-strength Portland cement, sulfate-resistant Portland cement, moderate-heat Portland cement, low-heat Portland cement, white Portland cement, etc. Blended cement is a cement in which various admixtures are mixed with Portland cement, and examples thereof include blast-furnace cement, silica cement, fly ash cement, etc.

[0016] Examples of aggregates are fine aggregate and coarse aggregate. Only fine aggregate may be used, or both fine and coarse aggregates may be used. Examples of fine aggregates are sand, crushed sand, blast furnace slag aggregate, ferronickel slag aggregate, copper slag fine aggregate, electric furnace oxidized slag aggregate, molten slag aggregate, recycled aggregate, etc. Examples of coarse aggregates are gravel, crushed stone, blast furnace slag aggregate, ferronickel slag aggregate, electric furnace oxidized slag aggregate, molten slag aggregate, recycled aggregate, etc. The recycled aggregate includes modified recycled aggregate in which CO2 is fixed and carbonated.

[0017] Examples of admixtures include admixtures, additives, etc. Examples of admixtures include air-entraining agents, air-entraining water-reducing agents, water-reducing agents, high-performance air-entraining water-reducing agents, superplasticizers, separation-reducing agents, foaming agents, setting and hardening regulators, quick-setting agents, rust inhibitors, waterproofing agents, etc. Examples of admixtures include ultrafine powders (ground granulated blast furnace slag, fly ash, silica fume, etc.), polymers for mixing with cement, expansive agents, etc.

[0018] There is no particular restriction on the method of using the air permeability improver of the present invention in the production of a hardened body. For example, when the hardened body is cement concrete, it may be mixed together with various raw materials in the production of cement concrete by a conventional method. When the amount of the air permeability improver of the present invention is expressed in terms of basic organic aluminum salt, it is preferable that the amount of basic organic aluminum salt is in the range of 0.05 to 10 parts by mass per 100 parts by mass of aggregate. The lower limit of the range is more preferably 0.1 parts by mass, and the upper limit is more preferably 7.5 parts by mass, and further preferably 5 parts by mass.

[0019] Dicalcium silicate gamma phase (γC2S) is often considered to be an admixture, but in the presence of moisture, it exerts strong bonding power by absorbing CO2, contributing to improving the strength of the hardened body. The following reaction formula 1 is known. Formula 1: γC2S+CO2+H2O → (2-x)CaCO3+m(xCaO·SiO2·yCO2·zH2O)+nSiO2 hydrate

[0020] In hardened bodies containing γ-phase di-calcium silicate, even when the air permeability enhancer of the present invention is not used, a certain degree of air permeability can be obtained. This is considered to be due to the voids formed by drying and shrinkage of the hydrates generated by formula 1. On the other hand, when the air permeability improver of the present invention is used, a further improvement in air permeability is observed, but the reason for this is not clear, but the following mechanism is presumed. The reaction of formula 1 above occurs on the surface in contact with the air, and calcium carbonate produced as a reaction product creates a weakly alkaline environment. In this weakly alkaline environment, the basic organic aluminum salt in the air permeability enhancer of the present invention dissociates into an organic acid and aluminum ions, and the aluminum ions precipitate as gel-like aluminum hydroxide hydrate (Al(OH)3·nH2O) during hardening of the dicalcium silicate γ phase. When the aluminum hydroxide hydrate (Al(OH)3·nH2O) loses moisture during drying during curing, the voids become voids. It is presumed that the formation of these voids, combined with the formation of voids derived from the dicalcium silicate γ phase according to formula 1, forms a large number of voids from the surface to the inside. EXAMPLES

[0021] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0022] (Basic organic aluminum salt) The commercially available "Taxeram M-160P" was used as the basic organic aluminum acid salt. "Taxeram M-160P" is a powder made of basic aluminum lactate manufactured by Taki Chemical Industry Co., Ltd., and contains 35.0% by mass of Al2O3 and 48.0% by mass of lactic acid.

[0023] The raw material mix is ​​shown in Table 1. In addition to the actual mix amounts, Table 1 also shows the relative mix amounts in parentheses when the total amount of aggregate (sintered alumina + river sand + magnesia aggregate) is 400g, which is 100 parts.

[0024] [Table 1]

[0025] For Example 1 and Comparative Example 1, kneaded products were prepared by kneading the raw materials shown in Table 1. These kneaded products were subjected to the following evaluation tests. The amount of water in Table 1 is the amount of water adjusted so that Example 1 and Comparative Example 1 have the same kneading feel.

[0026] [Evaluation test] Pot life: The kneaded material was molded into a 3 cm diameter sphere in a mold, and the time until it lost its plasticity was measured by palpation in a CO2 atmosphere. Air permeability: The mixture was poured into a PVC pipe with an inner diameter of 5 cm and a height of 5 cm, cured in a CO2 environment for 3 days, cured in air for 4 days, and then dried at 105°C for 12 hours or more. After cooling to room temperature, the air permeability was measured using an air permeability measuring system (S-1200) manufactured by Serio Corporation.

[0027] Table 2 shows the results of the evaluation test.

[0028] [Table 2]

[0029] As can be seen from Table 2, Example 1 had a higher air permeability than Comparative Example 1, confirming the effect of Taxeram M-160P in improving air permeability.

Claims

1. An air permeability improver for hardened bodies containing di-calcium silicate gamma phase, which contains a basic organic aluminum salt.

2. A method for improving the air permeability of a hardened material containing a γ-phase di-calcium silicate, using a basic organic aluminum salt as an air permeability improver.

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