JP7135849B2 - Durability improver for impregnated hardened cement - Google Patents

Description

TECHNICAL FIELD The present invention relates to an impregnation-type hardened cement body durability improver. More specifically, it relates to an impregnation-type durability improver that suppresses water absorption of a cement-based hardening body and improves strength.

Cement-based hardening bodies such as cement, mortar, and concrete are widely used for civil engineering structures, architectural structures, concrete products, and the like. In recent years, the demand for high-durability concrete has increased due to the demand for earthquake resistance and long-life buildings.

It is known that most of the deterioration of cementitious hardening bodies is related to the intrusion of water into concrete, and that preventing this leads to an improvement in the durability of cementitious hardening bodies. Main waterproofing methods applied to the surface of cementitious hardening bodies include asphalt waterproofing, sheet waterproofing, coating film waterproofing, permeable coating waterproofing, and the like. In particular, permeable coating waterproofing can be applied to cement-based hardening bodies with a wide range and complicated shapes, and can be applied regardless of the condition of cement-based hardening bodies, so it is excellent in terms of ease of construction. . As an example of permeable coating waterproofing, it is known to apply a sodium silicate aqueous solution that imparts waterproofness by reacting with calcium ions or the like in concrete (Non-Patent Document 1).

Edited by Yoshio Kasai and Masanori Kobayashi, "Admixture Materials for Cement and Concrete", published by Gijutsu Shoin, 1993, p. 423-425

However, in the method described in Non-Patent Document 1, although the effect of suppressing water absorption was exhibited, a sufficient improvement in strength was not obtained. In addition, wet curing such as water sprinkling and sheet curing is essential in order to achieve the effect of suppressing water absorption.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an impregnation-type hardened cementitious product durability improver capable of improving the strength of the hardened cementitious product in addition to imparting sufficient waterproofness in air curing.

As a result of intensive studies, the present inventors have found that the above-mentioned hardened cementitious material can be improved by using an aqueous solution containing a fatty acid divalent metal salt having a specific number of carbon atoms and a polyoxyalkylene derivative as a durability improver. The present invention has been completed by obtaining the knowledge to solve the problem.

（式（１）において、Ｒ^１は炭素数１～３０の炭化水素基及び水素原子からなる群より選ばれた一種以上であり、Ｒ^２は水素原子及びメチル基からなる群より選ばれた一種以上であり、ＡＯはそれぞれ独立して炭素数２～４のオキシアルキレン基から選ばれる一種以上であり、ｎは前記オキシアルキレン基ＡＯの平均付加モル数であり、１～１００の数を表す。） That is, the present invention is the following [1].
[1] An impregnation-type cement-based hardened body durability improving agent, represented by the following formula (1) with a fatty acid divalent metal salt (A) of a fatty acid having 2 to 10 carbon atoms and a divalent metal An impregnation-type cement-based hardened body durability improver comprising an aqueous solution of a polyoxyalkylene derivative (B) that is liquid at 25°C.

(In formula (1), R ¹ is one or more selected from the group consisting of hydrocarbon groups having 1 to 30 carbon atoms and hydrogen atoms, and R ² is one selected from the group consisting of hydrogen atoms and methyl groups. Each AO is independently one or more selected from oxyalkylene groups having 2 to 4 carbon atoms, and n is the average number of added moles of the oxyalkylene group AO, representing a number of 1 to 100. )

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an impregnation-type cementitious hardening product durability improver capable of imparting sufficient waterproofness in air curing and improving the strength of the cementitious hardening product.

[Durability improver for impregnated hardened cement]
The impregnation-type cement-based hardened body durability improver of the present invention comprises a fatty acid divalent metal salt (A) of a fatty acid having 2 to 10 carbon atoms and a divalent metal, and a polyoxyalkylene derivative (B ) and an aqueous solution.
Here, the impregnation-type cement-based hardening material durability improving agent is applied to the surface of cement-based hardening material such as cement, mortar, concrete, etc., so that fine pores and gaps existing on the surface layer of the cement-based hardening material are removed. It can be buried and improves the durability of the cement-based hardening body.
Further, the term "improved durability" as used herein means that the waterproofness and strength of the cement-based hardening body are improved by applying the impregnation-type cement-based hardening body durability improver to the surface of the cement-based hardening body.
The waterproofness is evaluated from the amount of water absorbed by the cement-based hardened body, and the strength is evaluated from the compressive strength measured in accordance with JIS R5201 (physical test method for cement). be.

<Fatty acid divalent metal salt (A) of fatty acid having 2 to 10 carbon atoms and divalent metal>
The impregnation-type hardened cement body durability improver of the present invention is characterized by containing a divalent fatty acid metal salt (A) of a fatty acid having 2 to 10 carbon atoms and a divalent metal. This divalent fatty acid metal salt is a salt composed of a divalent metal ion and two molecules of fatty acid-derived carboxylic acid ions, and is specifically represented by the following formula (2).

ここで、上記式（２）において、ＲＣＯＯ^－は、炭素数２～１０の脂肪酸（ＲＣＯＯＨ）に由来する一価カルボン酸イオンであり、Ｒは炭素数１～９の炭化水素基である。Ｍは２価金属であり、Ｍ^２+は前記２価金属に由来する２価金属イオンである。

Here, in the above formula (2), RCOO ⁻ is a monovalent carboxylic acid ion derived from a fatty acid (RCOOH) having 2 to 10 carbon atoms, and R is a hydrocarbon group having 1 to 9 carbon atoms. M is a divalent metal, and M ²⁺ is a divalent metal ion derived from the divalent metal.

Here, the fatty acid (RCOOH) constituting the divalent fatty acid metal salt may be either a straight-chain fatty acid or a branched-chain fatty acid, but a branched-chain fatty acid is more preferable. If the number of carbon atoms of this fatty acid is more than 10, it will not be possible to fill the micropores and the like on the surface of the hardened cementitious product, making it impossible to improve the durability. By setting the number of carbon atoms to 9 or less, the effect of improving durability can be more exhibited, which is more preferable.
Specifically, the fatty acid constituting the divalent fatty acid metal salt is preferably a straight-chain fatty acid such as butyric acid, valeric acid, caproic acid, caprylic acid, or nonanoic acid, more preferably caproic acid or caprylic acid, and caproic acid. Especially preferred. The branched chain fatty acid is preferably isobutyric acid, isovaleric acid, 2-ethylhexanoic acid, isononanoic acid, etc., more preferably 2-ethylhexanoic acid or isononanoic acid, and particularly preferably 2-ethylhexanoic acid.

The divalent metal constituting the divalent fatty acid metal salt is preferably an alkaline earth metal such as magnesium or calcium, more preferably magnesium.

<Polyoxyalkylene derivative (B) liquid at 25°C>
The impregnation-type hardened cement body durability improver of the present invention is characterized by containing a polyoxyalkylene derivative (B) that is liquid at 25° C. represented by the following formula (1).

The polyoxyalkylene derivative (B) represented by the above formula (1) is characterized by being liquid at 25°C.
The polyoxyalkylene derivative (B), which is liquid at 25°C, can be easily handled and used.

In formula (1), R ¹ is one selected from the group consisting of hydrocarbon groups having 1 to 30 carbon atoms and hydrogen atoms, and R ¹ preferably has 1 to 22 carbon atoms, more preferably 1 to 18 carbon atoms. . R ¹ is specifically a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, hexadecyl group, octadecyl group, isostearyl group and the like.

In formula (1), R ² is one or more selected from the group consisting of a hydrogen atom and a methyl group, more preferably a hydrogen atom. In formula (1), as a combination of R ¹ and R ² , a combination in which R ¹ is a hydrocarbon group having 1 to 8 carbon atoms and R ² is a hydrogen atom is more preferable from the viewpoint of excellent improvement in durability.

In formula (1), each AO is independently one or more selected from oxyalkylene groups having 2 to 4 carbon atoms. The oxyalkylene group having 2 to 4 carbon atoms includes oxyethylene group, oxypropylene group, oxybutylene group, oxytetramethylene group and the like. Two or more selected from an oxyalkylene group having 2 carbon atoms and one or more oxyalkylene groups having 3 to 4 carbon atoms are more preferable. In addition, the oxyalkylene group may be added randomly or in blocks.

In formula (1), the average number of added moles of AO is 1-100. The upper limit is preferably 50 or less, more preferably 30 or less, and even more preferably 20 or less.

In the impregnation-type cement-based hardening body durability improving agent of the present invention, the mixing ratio of the component (A) and the component (B) is not particularly limited, but preferably 1 to 50 parts by mass of (A): (B) 99 to 50 parts by mass. More preferably (A) 5 to 40 parts by mass: (B) 95 to 60 parts by mass, more preferably (A) 10 to 35 parts by mass: (B) 90 to 65 parts by mass, particularly preferably (A) 20 to 30 parts by mass: (B) 80 to 70 parts by mass.
By setting the mixing ratio of the component (A) and the component (B) within the above range, the water absorption in the air curing can be further suppressed, and the strength of the cement-based hardened body can be further improved.

<Aqueous solution>
The impregnation-type hardened cement body durability improver of the present invention is characterized by being an aqueous solution. By making it an aqueous solution, it can be easily applied to a cement-based hardening material having a wide range or a complicated shape. Furthermore, since it is only necessary to mix the components (A), (B), and water on site, the impregnation-type cement-based hardened body durability improver can be prepared more easily.

The impregnation-type cement-based hardening body durability improver of the present invention is an aqueous solution containing the above components (A) and (B) in a total content of preferably 1 to 70% by mass. The lower limit is more preferably 10% by mass or more, and still more preferably 20% by mass or more. The upper limit is more preferably 50% by mass or less, and even more preferably 40% by mass or less.
By setting the total content of the component (A) and the component (B) within the above range, the effect of improving durability can be imparted to the cement-based hardened body.

The impregnation-type hardened cement body durability improver of the present invention is applied or sprayed onto the surface of hardened cement bodies such as mortar and concrete.
As a method for applying, spraying or spraying the impregnated cement-based hardening body durability improver, for example, for application, any brush or roller that can apply an aqueous solution to the cement-based hardening body can be used. be able to. In addition, for spreading or spraying, either a hand pump type sprayer, a mechanical sprayer, or the like can be used. Although the temperature during construction is not particularly limited, it is preferably 5 to 35°C.

The amount of the impregnation-type cement-based hardened body durability improver of the present invention used is not particularly limited, but it is preferably used in the range of 50 to 500 g, more preferably 100 to 400 g, per 1 m ² . By making it 50 g or more, the effect of suppressing water absorption and the effect of improving strength can be sufficiently exhibited. Moreover, the amount used can be reduced by making it 500 g or less.

Cement that can be used in the impregnation-type cement-based hardened body durability improver of the present invention includes Portland cement such as normal, early-strength, ultra-early-strength, low-heat, moderate-heat, sulfate-resistant, and blast-furnace slag, Examples include various mixed cements mixed with fly ash or silica, ecocement, white cement, ultra fast hardening cement, and the like.

Aggregates that can be used in the impregnation-type cement-based hardening body durability improver of the present invention are not particularly limited as long as they can be used in ordinary concrete or mortar, and are river sand, mountain sand, land sand, and crushed sand. , fine aggregate such as silica sand, and coarse aggregate such as river gravel, mountain gravel, land gravel, crushed stone, artificial lightweight aggregate, blast furnace slag crushed stone and recycled aggregate.

Other additives (additives) can be used in the impregnation-type cement-based hardened body durability improver of the present invention within a range that does not impair its effects. Other additives include water reducing agents, AE agents, AE water reducing agents, drying shrinkage reducing agents, defoaming agents, air amount adjusting agents, setting retarders, setting accelerators, swelling agents, fluidizing agents, foaming agents, separation Inhibitors, water retention agents, thickeners, waterproofing agents, curing agents and the like can be mentioned.

The present invention will be described below with reference to examples.
<Manufacture of mortar>
100 parts by mass of moderate heat cement (manufactured by Taiheiyo Cement Co., Ltd.) and 170 parts by mass of fine aggregate (mountain sand) were weighed, and after empty kneading with a forced kneading mixer, 34 parts by mass of water and a water reducing agent (Malialim AKM-60F, NOF) Co., Ltd.) [0.6% by mass relative to cement] was added and kneaded to form mortar. The mortar temperature was 20±2° C., and the unit volume mass determined according to JIS A 1116 “Test method for unit volume mass of fresh concrete and test method for air content by mass” was 2,150±30 g/L.
Fatty acid divalent metal salts (A) (compounds A-1 to A-3) used in Examples and Comparative Examples are shown in Table 1, and polyoxyalkylene derivatives (B) (compounds B-1 to B-5) were Table 2 shows. Table 3 shows the results of the water absorption ratio and strength ratio for the number of applications, and Table 4 shows the results of the water absorption ratio and strength ratio in each example.

(Evaluation method)
<Preparation of specimen>
The above mortar was filled in a mold of 4 cm×4 cm×16 cm, and removed from the mold one day later to obtain a specimen. After that, about 4.3 g (about 150 g/m ² ) of a durability improving agent was weighed out per one test piece, and the entire surface of the obtained test piece was sprayed with a sprayer. Curing (20±2° C., humidity 60±5%) was performed. When multiple coatings were applied, the second coating was applied 7 days after kneading, and the third coating was applied 14 days after kneading.

<Evaluation of waterproofness>
Based on the water absorption measurement described in JIS A1404 (testing method for cement waterproofing agents for construction), waterproofness was evaluated after 1 hour.
After 20 days from kneading, the test piece was dried in a dryer at about 80° C. for about 8 hours, and the mass at the time of drying was measured.
Place the test piece 21 days after kneading in a room at a temperature of 20±3°C with the filled surface facing downward and the bottom 2 cm constantly being submerged in water. The mass when weighed immediately was taken as the mass at the time of water absorption. The water absorption amount and water absorption ratio were determined by the following formulas. From the following formula, it can be said that the smaller the value of the water absorption ratio, the more excellent the waterproofness of the impregnation type cement-based hardened body durability improver.

<Evaluation of strength>
Compressive strength was measured after 28 days using a test piece that had been kneaded for 28 days. Compressive strength was measured according to JIS R5201 (physical test method for cement). It can be said that the larger the value of the strength ratio, the more excellent the strength-improving property of the impregnated cement-based hardened body durability improver.

From the results in Table 3, Example 1 using the impregnation-type cement-based hardening body durability improver of the present invention suppresses water absorption of mortar even in air curing and improves strength as the number of times of application increases. I found out that I can. On the other hand, it was found that Comparative Example 1, in which the agent not containing the component (A) was applied, was not sufficiently effective in improving waterproofness and strength by curing in the air.

From the results in Table 4, when Examples 2 to 6 and Comparative Examples 2 to 6 are compared, when the impregnation-type cement-based hardened body durability improver of the present invention is applied, water absorption of mortar is suppressed even in air curing. was found to improve strength.

In Comparative Example 2, only water was applied, but it was found that air curing could not suppress the water absorption of the mortar.
In Comparative Example 3, the undiluted solution of the polyoxyalkylene derivative (B) was applied, and the result was inferior in suppressing the water absorption of the mortar.
In Comparative Example 4, the undiluted solution of the fatty acid divalent metal salt (A) and the polyoxyalkylene derivative (B) was applied, resulting in poor suppression of water absorption and improvement in strength of the mortar.
In Comparative Example 5, an aqueous solution containing only the fatty acid divalent metal salt (A) was applied, and it was found that the strength of the mortar was not improved.
In Comparative Example 6, the number of carbon atoms in the fatty acid constituting the fatty acid divalent metal salt was outside the scope of the present invention, so an aqueous solution could not be prepared. Then, since it could not be sprayed with a sprayer, it was applied with a brush and evaluated. The result was the same as in Comparative Example 1, and the divalent metal salt of fatty acid did not suppress the water absorption of the mortar and did not improve the strength.

Claims (1)

A fatty acid divalent metal salt (A) of an impregnation-type cementitious hardened body durability improver comprising a fatty acid having 2 to 10 carbon atoms and a divalent metal, and at 25 ° C. represented by the following formula (1) It consists of an aqueous solution with a liquid polyoxyalkylene derivative (B), and the mixing ratio of the component (A) and the component (B) is 20 to 30 parts by mass of (A): 80 to 70 parts by mass of (B). , an impregnation-type cement-based hardened body durability improver comprising an aqueous solution containing the total content of the component (A) and the component (B) in the range of 20 to 40 % by mass.

(In formula (1), R ¹ is one or more selected from the group consisting of hydrocarbon groups having 1 to 30 carbon atoms and hydrogen atoms, and R ² is one selected from the group consisting of hydrogen atoms and methyl groups. Each AO is independently one or more selected from oxyalkylene groups having 2 to 4 carbon atoms, and n is the average number of added moles of the oxyalkylene group AO, representing a number of 1 to 100. )