JP2016169128A - Foaming agent for cement compositions and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foaming agent for cement compositions that can improve the expansibility of cement compositions, and provide a cement composition with high expansibility.SOLUTION: The foaming agent comprises an azo compound and a hydrazine derivative, where a mass ratio of the azo compound to a total mass of the azo compound and the hydrazine derivative is 0.35 or more and 0.65 or less.SELECTED DRAWING: None

Description

  The present invention relates to a foaming agent for a cement composition and a cement composition containing the foaming agent.

Cement compositions are used as fillers used to repair cross sections of mortars and concrete structures, etc., but if such cement compositions shrink significantly before hardening, it may cause cracks in the filling area. Become. Therefore, it is considered to suppress cracking by blending a foaming agent in the cement composition and imparting expansibility to the cement composition.
As such foaming agents for cement compositions, for example, Patent Document 1 includes aluminum powder, azo compounds, hydrazine derivatives, and the like.

  The aluminum powder reacts with an alkali component in the cement to generate hydrogen gas when it comes into contact with the cement and water, so that expandability can be imparted to the cement composition after kneading. However, since aluminum powder has high reactivity, there is a problem that the reaction is completed in a short time after blending with the cement composition, and foamability cannot be maintained for a long time. In particular, if the foaming agent is mixed (premixed) with cement and other components in advance, the foaming property of the foaming agent decreases due to reaction with slight moisture in the components. When used, it is difficult to obtain desired expansibility.

Azo compounds and hydrazine derivatives react with alkali components in cement by contact with cement and water to generate nitrogen gas, and have a slower reaction rate than aluminum powder, especially premixed cement composition It is suitable as a foaming agent for products.
However, the azo compound has a high temperature dependency of the foaming reaction, and cannot stably impart expansibility to the cement composition depending on the environmental temperature.
Moreover, since the hydrazine derivative has a relatively low foaming property, it is difficult to impart sufficient expansibility to the cement composition. In particular, in the case of a cement composition using an early-strength cement that hardens in a relatively short time, it is difficult to impart sufficient expandability to the cement composition before hardening.

JP 2009-126719 A

  Therefore, in view of the conventional problems as described above, the present invention can exhibit a foaming agent for a cement composition that can stably improve the expansibility of the cement composition, and a stable and highly expansible material. It is an object to provide a cement composition.

  The foaming agent for a cement composition according to the present invention includes an azo compound and a hydrazine derivative, and a ratio of a mass of the azo compound to a total mass of the azo compound and the hydrazine derivative is 0.35 or more and 0.65 or less. It is.

  According to the present invention, since the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative is within the above range, the foaming reactivity is maintained even when the environmental temperature changes. It is difficult to change and the foamability can be improved. Therefore, when it mix | blends with a cement composition, the expansibility of a cement composition does not fall easily with environmental temperature, and a comparatively high expansibility can be provided to a cement composition. As a result, the expansibility of the cement composition can be stably improved.

  This invention concerning a cement composition contains the said foaming agent and cement.

  The cement composition of the present invention may contain 0.04% by mass or more and 0.07% by mass or less of the foaming agent.

  When the foaming agent is included in the above range, the foaming reactivity is hardly changed even when the environmental temperature is changed, and the foaming property is good. Therefore, a cement composition that can stably exhibit high expansibility is obtained.

  In the cement composition of the present invention, the cement may contain a calcium aluminate mineral.

  When the cement contains a calcium aluminate-based mineral, the cement composition can be cured relatively early, and at the same time, the expansion can be improved while suppressing the decrease in the expansion due to the environmental temperature. it can.

  As described above, according to the present invention, a foaming agent for a cement composition that can stably improve the expansibility of the cement composition and a cement composition that can stably exhibit high expansibility are provided. be able to.

  Hereinafter, an embodiment of a foaming agent for a cement composition and a cement composition according to the present invention will be described.

  The foaming agent for cement composition of the present embodiment (hereinafter also simply referred to as a foaming agent) includes an azo compound and a hydrazine derivative, and the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative is 0. .35 or more and 0.65 or less.

  The azo compound used in the foaming agent of the present embodiment is not particularly limited as long as it can react with the alkali component in the cement and generate nitrogen gas by contacting with water and cement. Examples thereof include azodicarbonamide and azobisisobutylnitrile. Of these, azodicarbonamide is preferred because of its good foamability.

  A commercially available product may be used as the azo compound. For example, as a commercially available product of azodicarbonamide, a trade name “VINYHALL” (manufactured by Eiwa Kasei Kogyo Co., Ltd.) and the like can be mentioned.

The hydrazine derivative used in the foaming agent of the present embodiment is not particularly limited as long as it can react with the alkaline component in the cement and generate nitrogen gas by contacting with water and cement. For example, p-toluenesulfonyl hydrazide, p, p′-oxybis (benzenesulfonylhydrazide), 4,4′-oxybis (benzenesulfonylhydrazide), benzenesulfonylhydrazide, hydrazinecarbonamide and the like can be mentioned.
Among these, 4,4′-oxybis (benzenesulfonylhydrazide) is preferable because it can exhibit foamability stably even with a temperature change.

  A commercially available product may be used as the hydrazine derivative. For example, as a commercially available product of 4,4′-oxybis (benzenesulfonylhydrazide), a trade name “Neocerbon” (manufactured by Eiwa Kasei Kogyo Co., Ltd.) and the like can be mentioned.

  The combination of the azo compound and the hydrazine derivative in the foaming agent is not particularly limited. For example, it is preferable to use azodicarbonamide as the azo compound and 4,4′-oxybis (benzenesulfonylhydrazide) as the hydrazine derivative. By adopting such a combination, foamability can be stably exhibited even when the environmental temperature changes, and foamability is improved.

  In the foaming agent of this embodiment, the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative is 0.35 or more and 0.65 or less, preferably 0.50 or more and 0.60 or less. When the mass ratio of the azo compound is within the above range, when blended with a cement composition as a foaming agent, it is possible to suppress the expansion of the cement and water when the cement and water are mixed, and to expand Can be improved.

  In addition, the foaming agent of this embodiment may contain components other than an azo compound and a hydrazine derivative.

The cement composition of this embodiment contains the foaming agent and cement for the cement composition of this embodiment as described above.
The cement composition of this embodiment can be used as a filler used for, for example, repairing a cross section of a mortar or a concrete structure.

The cement used for the cement composition of the present embodiment is not particularly limited.
For example, normal Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderately hot Portland cement, sulfate-resistant Portland cement, white Portland cement and other Portland cements, ultrafast cement, alumina cement and the like can be mentioned. Moreover, various mixed cements in which fly ash, blast furnace slag, etc. are mixed with Portland cement can also be used.
Among these, a super-hard cement is preferable when a cement composition is used as a filler because desired strength can be obtained at an early stage.

Examples of the cement that can obtain desired strength at an early stage, such as such an ultrafast cement, include a cement containing a calcium aluminate mineral.
As cement containing calcium aluminate mineral, crystalline or amorphous such as 11CaO · 7Al ₂ O ₃ · CaX ₂ (X is a halogen element), 12CaO · 7Al ₂ O ₃ , calcium sulfoaluminate (Erwin) The thing containing these calcium aluminates can be illustrated.

The content of the cement foaming agent of the present embodiment is preferably 0.04% by mass or more and 0.07% by mass or less, and more preferably 0.05% by mass or more and 0.000% by mass or less in the mixture of cement and foaming agent. It is 06 mass% or less, Most preferably, it is 0.050 mass% or more and 0.055 mass% or less.
When the content of the foaming agent in the cement composition is in the above range, it is possible to effectively suppress the change in the expandability when the cement and water are mixed, and to further improve the expandability. be able to.

The cement composition of the present embodiment may further contain water, and may further contain another component. Other components include coarse aggregates, aggregates such as fine aggregates, powder components such as admixtures, fibers such as steel fibers, vinylon fibers, and polypropylene fibers, polymer dispersions, shrinkage reducing agents, rust preventives, and water reducing agents. Examples thereof include liquid or powder components such as agents and retarders.
In this case, for example, a foaming agent, cement, and other powder components may be mixed and mixed with water and other liquid components immediately before use.

  For example, water is blended so that the water cement ratio is 30% or more and 65% or less. By blending water in the above range, a cement composition that is easy to use as a filler that can be easily filled in cracks and repaired parts can be obtained.

The cement composition of this embodiment is obtained as a fresh cement composition by, for example, blending water and stirring and mixing using a mixer or the like.
In a cement composition containing a foaming agent, the amount of expansion is usually small when the environmental temperature is low, and the amount of expansion is large when the environmental temperature is high. However, the cement composition of this embodiment has an expansion amount of 0.2 mm or more and 1.0 mm or less, preferably 0.4 mm or more and 0 mm or less at 5 ° C. to 30 ° C., which is measured by the method for measuring the expansion amount of Examples described later. .8 mm or less.
When the expansion amount is in the above range, the expansion property can be sufficiently exhibited in the range of the environmental temperature of 5 ° C. to 30 ° C., and as a result, cracking can be suppressed.

The cement composition may shrink and crack when the amount of expansion is small, but cracks (expandable cracks) may also occur when the amount of expansion is too large. A range is preferable.
In addition, when the amount of expansion changes greatly due to a temperature change, the performance cannot be exhibited stably. Therefore, it is preferable that stable expansion can be exhibited in as wide a range as possible.

  Further, since the cement composition of the present embodiment hardly causes a foaming reaction until mixed with a liquid component such as water, for example, only the powder component may be mixed and stored in a premixed state. The foaming performance of the foaming agent is unlikely to decline. Therefore, even if it is stored in a premixed state, a decrease in expansibility when mixed with water can be suppressed.

  The cement composition of the present embodiment is suitable as a filler used for, for example, mortar and concrete structure cross-section repair. When used as a filler, since stable expandability can be exhibited in a wide temperature range, shrinkage after filling is suppressed, and generation of cracks can be suppressed.

  In addition, although the foaming agent and cement composition concerning this embodiment are as above, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  EXAMPLES The following examples further illustrate the foaming agent and cement composition according to the present invention, but the present invention is not limited to the following examples.

  The materials shown in Table 1 were used as the foaming agent material.

  As raw materials for the cement composition other than the foaming agent, those shown in Table 2 were used. Further, Table 3 shows the composition other than the foaming agent.

The blending amount of the foaming agent in the cement composition is shown in Table 4 to Table 7 in mass% with respect to the cement.
The blending amount of the hydrazine derivative and azo compound as the foaming agent is the hydrazine derivative and azo compound calculated from the purity, with the blending amount (to the cement mass ratio) of each product shown in Table 1 as “Product (C ×%)”. The converted compounding amounts of the compounds are shown in Tables 4 to 7 as “(C ×%)”.

<Measurement of expansion amount>
The amount of expansion of each cement composition was measured by the following method.

(Specimen preparation method)
First, a specimen was prepared by the following method using each cement composition.
Each cement composition was kneaded for 2 minutes using a forced kneading pan mixer having a capacity of 50 L as a mixing device. After kneading, a specimen (diameter 10 cm, height 20 cm) was prepared in accordance with JIS A 1132 and immediately placed in an expansion measuring device.

(Expansion amount)
The amount of expansion of each specimen was measured.
The measurement of the amount of expansion was performed according to JASS 5T-503: 2009. A non-contact sensor (laser displacement meter) was used as a measuring device, and the upper surface displacement of the specimen was continuously measured.

Table 4 shows the measurement results of the amount of expansion using a cement composition using either an azo compound or a hydrazine derivative as a foaming agent.
As shown in Table 4, when the azo compound is used alone, any suitable expansion range is 0.2 mm or more and 1.0 mm or less, and any of 5 ° C., 10 ° C., 20 ° C., and 30 ° C. It was shown to deviate in temperature.
On the other hand, when the hydrazine derivative was used alone, the expansion amount was too small at any temperature.

Table 5 shows the ratio of the mass of the azo compound to the total mass of the azo compound AC # 3-K7 (symbol K) and the hydrazine derivative N # 5000 (symbol N5) with respect to the total mass of the azo compound and the hydrazine derivative. The measurement results of the expansion amount of the cement composition using the foaming agent mixed so as to have a ratio and also changing the blending amount of the foaming agent with respect to the cement are shown.
As shown in Table 5, the cement composition in which the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative is 0.35 or more and 0.65 or less has an expansion amount of 0.2 mm or more at any temperature. It was 1.0 mm or less.

Table 6 shows the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative using the azo compound, FE-788 (symbol FE) and the hydrazine derivative N # 5000 (symbol N5). The measurement results of the expansion amount of the cement were shown using the foaming agent mixed so as to have each ratio and also changing the blending amount of the foaming agent with respect to the cement.
As shown in Table 6, when the ratio of each cement composition was outside the range of 0.35 to 0.65, the expansion amount exceeded 1.0 mm at 5 ° C. In particular, when the blending amount of the foaming agent decreases, the expansion amount increases.

Table 7 shows azo compounds, AC # R (symbol R), AC # K3-TA (symbol TA) and hydrazine derivatives N # 5000 (symbol N5), N # 1000S (symbol N1S) and N # 1000M (symbol N1M). ) With a foaming agent in which the ratio of the mass of the azo compound to the total mass of the azo compound and the hydrazine derivative is equal to each ratio in the table, and the blending amount of the foaming agent with respect to the cement is changed. The measurement result of the amount of expansion was shown.
As shown in Table 7, the cement composition in which the ratio is 0.35 or more and 0.65 or less, regardless of which azo compound or hydrazine derivative is used, has an expansion amount of 0.00 at any temperature. It was 2 mm or more and 1.0 mm or less.

Claims (4)

An azo compound and a hydrazine derivative,
A foaming agent for a cement composition, wherein a ratio of a mass of the azo compound to a total mass of the azo compound and the hydrazine derivative is 0.35 or more and 0.65 or less.   A cement composition comprising the foaming agent for cement composition according to claim 1 and cement.   The cement composition according to claim 2, comprising 0.04% by mass or more and 0.07% by mass or less of the foaming agent with respect to the cement. The cement composition according to claim 2 or 3, wherein the cement is a cement containing a calcium aluminate mineral.