JP6488339B2 - Cement admixture and hydraulic composition - Google Patents

Description

  The present invention relates to a cement admixture and a hydraulic composition used in the field of civil engineering, construction, and the like.

  In recent years, hydraulic compositions have been required to have a wide variety of performances in the civil engineering and architectural fields. Among them, simplification of construction is a very important factor in considering the safety of workers. Here, the simplification of construction refers to, for example, comprehensive rationalization such as improvement of construction speed, integration of materials, and improvement of handleability. In order to achieve the simplification of construction, for example, it is the key to improve the curing speed of the hydraulic composition, premix, etc., and in fact, various hydraulic compositions having super-fast hardness are proposed. (For example, Patent Documents 1 to 3). In recent years, the performance required for the hydraulic composition has been increased more and more with the further improvement of simplification of construction and the correspondence to new applications.

Japanese Patent Laid-Open No. 3-12350 Japanese Patent Laid-Open No. 1-230455 Japanese Patent Laid-Open No. 11-139859

In the hydraulic composition, a cement admixture is blended for the purpose of improving various properties such as a curing rate. As the cement admixture, an alkaline one has been conventionally used, but it is desired to use an acidic one from the viewpoint of safety.
However, since a hydraulic substance such as cement is strongly alkaline, it is difficult to combine it with an acidic cement admixture, and there is a problem that a hydraulic composition having desired characteristics cannot be obtained. In fact, when a conventional acidic cement admixture suitable for improving the curing speed and premixing is added to the hydraulic composition, the storage stability of the hydraulic composition, the strength of the cured product, and the like are lowered.

The present invention has been made in order to solve the above-described problems, and even when blended in advance with a hydraulic composition, the storage stability is unlikely to decrease, and it has super-fast hardness and the strength of a cured product is high. An object of the present invention is to provide a cement admixture capable of giving a high hydraulic composition.
Another object of the present invention is to provide a hydraulic composition that is not easily lowered in storage stability, has super-fast hardness, and has high strength of a cured product.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that aluminum sulfate hydrate having specific properties is suitable as a cement admixture despite being acidic. As a result, the present invention has been completed.
That is, the present invention is a cement admixture containing aluminum sulfate hydrate that is amorphous and has a weight loss of 5 to 40% by mass when ignited at 500 ° C.
Moreover, this invention is a hydraulic composition containing the said cement admixture and an alkaline hydraulic substance.

ADVANTAGE OF THE INVENTION According to this invention, the cement admixture which can give the hydraulic composition which is hard to fall in storage stability even if it mix | blends beforehand with a hydraulic composition, and has super-fast-hardness and the intensity | strength of a hardening body is high. Can be provided.
Further, according to the present invention, it is possible to provide a hydraulic composition that is less likely to be deteriorated in storage stability, has super fast hardness, and has a high strength of a cured product.

The cement admixture of the present invention contains an Al ₂ O ₃ —SO ₃ -based compound. This Al ₂ O ₃ —SO ₃ compound is amorphous and has a weight loss (ignition loss) of 5 to 40% by mass when ignited at 500 ° C.
When the Al ₂ O ₃ —SO ₃ based compound is not amorphous, it is difficult to premix with a hydraulic material having strong alkalinity such as cement, and storage of the hydraulic composition even if it can be premixed. Stability is reduced.
Here, whether or not the Al ₂ O ₃ —SO ₃ compound is amorphous can be determined by X-ray diffraction analysis. Specifically, if the X-ray diffraction spectrum of the Al ₂ O ₃ —SO ₃ compound is broad, it can be determined to be amorphous.

Moreover, the hardening rate of a hydraulic composition will fall that the weight loss at the time of ignition at 500 degreeC is less than 5 mass%. On the other hand, when the weight loss when ignited at 500 ° C. exceeds 40% by mass, the storage stability of the hydraulic composition is lowered. The weight loss when ignited at 500 ° C. is preferably 10 to 40% by mass from the viewpoint of stably improving the curing rate and storage stability of the hydraulic composition.
Here, in this specification, the weight loss when ignited at 500 ° C. (ignition loss) means the weight loss when the Al ₂ O ₃ —SO ₃ compound is ignited at 500 ° C. for 1 hour, It is calculated by the following equation (1).
Loss on ignition = (m−m ′) / m × 100 (1)
m: mass of Al ₂ O ₃ —SO ₃ compound before ignition m ′: mass of Al ₂ O ₃ —SO ₃ compound after ignition

The Al ₂ O ₃ —SO ₃ compound used in the cement admixture of the present invention can be produced using an Al ₂ O ₃ source and an SO ₃ source. The production method is not particularly limited. For example, a method in which an Al ₂ O ₃ source and an SO ₃ source are mixed and heat-treated, a method in which an Al ₂ O ₃ source and an SO ₃ source are directly subjected to a chemical reaction, Al ₂ O _{For example, a method in which the 3} sources and the SO ₃ source are put into a solvent such as pure water and mixed and then subjected to a chemical reaction can be used. In these methods, an Al ₂ O ₃ —SO ₃ -based compound having the above characteristics can be obtained by controlling the production conditions. For example, in the case of using a method in which an Al ₂ O ₃ source and an SO ₃ source are introduced into a solvent and mixed and then subjected to a chemical reaction, by controlling conditions such as the reaction temperature, the Al ₂ O ₃ —SO ₃ compound The ignition loss can be adjusted. The reaction temperature at this time varies depending on the types and blending ratios of the Al ₂ O ₃ source and SO ₃ source to be used and cannot be uniquely defined, but is typically 70 ° C. to 280 ° C.

The Al ₂ O ₃ source is not particularly limited, and aluminum sulfate, aluminate, other inorganic aluminum compounds, organic aluminum compounds, and aluminum complexes can be used.
The sulfate of aluminum is not particularly limited, and examples thereof include ammonium alum, aluminum hydroxysulfate, and aluminum sulfate.
The aluminate is not particularly limited, and examples thereof include lithium aluminate, sodium aluminate, potassium aluminate, calcium aluminate, and magnesium aluminate.
Other inorganic aluminum compounds are not particularly limited. For example, bauxite, aluminum oxide, aluminum hydroxide, aluminum chloride, aluminum phosphate, aluminum nitrate, aluminum fluoride, polyaluminum chloride, aluminum carbonate hydroxide, synthetic hydrotal Sites, and aluminum metasilicate.

The organoaluminum compound is not particularly limited, and examples thereof include aluminum stearate, aluminum oxalate, aluminum isopropoxide, and aluminum formate.
Although it does not specifically limit as an aluminum complex, For example, a tris (8-hydroxy quinolinato) aluminum etc. are mentioned.
As the Al ₂ O ₃ source, a single species can be used, but two or more species may be used in combination. Of the various Al ₂ O ₃ sources described above, aluminum sulfate is preferred because of its high solubility in water, low production costs, and excellent coagulation properties.

The SO ₃ source is not particularly limited, but includes sulfur, sulfuric acid, sulfate, sulfurous acid, sulfite, thiosulfuric acid, thiosulfate, and organic sulfur compounds in addition to sulfur in the elemental state such as sulfur and sulfur flower. Can be used.
The sulfide is not particularly limited, and examples thereof include magnesium sulfide, calcium sulfide, iron sulfide, and phosphorus pentasulfide.
The sulfate is not particularly limited, and examples thereof include aniline sulfate, aluminum sulfate, ammonium sulfate, magnesium sulfate, manganese sulfate, barium sulfate, calcium sulfate, sodium alum, potassium alum, ammonium alum, and hydroxylamine sulfate.

The sulfite is not particularly limited, and examples thereof include ammonium bisulfite and calcium sulfite.
The thiosulfate is not particularly limited, and examples thereof include ammonium thiosulfate and barium thiosulfate.
The organic sulfur compound is not particularly limited, and examples thereof include resins such as sulfonic acid derivatives, salts of sulfonic acid derivatives, mercaptans, thiophenes, thiophene derivatives, polysulfone, polyethersulfone, and polyphenylene sulfide.
As the SO ₃ source, a single species can be used, but two or more species may be used in combination. Of the various SO ₃ sources described above, sulfate is preferable, and ammonium alum is most preferable because of its high solubility in water, low production costs, and excellent coagulation.

The Al ₂ O ₃ —SO ₃ compound used in the cement admixture of the present invention has a true density of 1.9 to 2.3 g / cm ³ from the viewpoint of improving the curing rate and storage stability of the hydraulic composition. It is preferable that When the true density is less than 1.9 g / cm ³ , the storage stability of the hydraulic composition may be lowered. On the other hand, if the true density exceeds 2.3 g / cm ³ , the curing rate of the hydraulic composition may decrease.
Here, the true density of the Al ₂ O ₃ —SO ₃ -based compound can be measured using a commercially available density meter.

Al ₂ O ₃ -SO ₃ compound used in the cement admixture of the present invention, from the viewpoint of improving the cure rate of the hydraulic composition is preferably a BET specific surface area is less than 5m ² / g, 3m ² / G or less is more preferable. When the BET specific surface area exceeds 5 m ² / g, the effect of improving the curing rate of the hydraulic composition may not be obtained, and the labor of the pulverization process increases, leading to an increase in cost.
Here, the BET specific surface area of the Al ₂ O ₃ —SO ₃ compound can be measured using a commercially available BET specific surface area measuring device.

The Al ₂ O ₃ —SO ₃ compound used in the cement admixture of the present invention has a chemical shift in the spectrum obtained by solid ²⁷ Al-NMR from the viewpoint of improving the curing rate and storage stability of the hydraulic composition. It is preferable to have a peak at −0.51 to −23.21 ppm and that the full width at half maximum is 5 ppm or more. When the peak chemical shift is larger than −0.51 ppm, it is difficult to premix with a hydraulic substance, and even if it can be premixed, the storage stability of the hydraulic composition may be lowered. On the other hand, if the peak chemical shift is smaller than −23.21 ppm, the effect of improving the curing rate of the hydraulic composition may not be obtained. Moreover, when the half width is less than 5 ppm, the effect of improving the curing rate and storage stability of the hydraulic composition may not be sufficiently obtained.

Here, the solid ²⁷ Al-NMR measurement of the Al ₂ O ₃ —SO ₃ based compound is carried out using a commercially available measurement device, for example, a superconducting nuclear magnetic resonance device “ECX-400” manufactured by JEOL Ltd. Can be done under conditions.
Observation nucleus: ²⁷ Al
Sample tube rotation speed: 10KHz
Measurement temperature: room temperature Pulse width: 3.3 μsec (90 ° pulse)
Waiting time: 5 seconds External standard: Aluminum nitrate

The Al ₂ O ₃ —SO ₃ compound used in the cement admixture of the present invention is an OH group stretching vibration in the spectrum obtained by FT-IR from the viewpoint of improving the curing rate and storage stability of the hydraulic composition. The ratio of the peak area derived from SO ₄ group stretching vibration to the peak area derived from is preferably 0.2 to 3.0. When the ratio of peak areas is less than 0.2, the effect of improving the curing rate of the hydraulic composition may not be obtained. On the other hand, when the ratio of peak areas exceeds 3.0, the storage stability of the hydraulic composition may decrease.

Here, FT-IR (Fourier transform infrared spectroscopic analysis) of the Al ₂ O ₃ —SO ₃ compound is performed by a ATR method using a commercially available FT-IR apparatus, for example, Frontier manufactured by Perkin Elmer. Can do.
In this specification, the peak derived from OH group stretching vibration appears around the 3,000 cm ^-1, the peak areas derived from the area of the peak centered at 3,000 cm ^-1, the OH group stretching vibration It was. Furthermore, peaks derived from SO ₄ group stretching vibration to appear around the 1,100Cm ^-1, the area of the peak centered at 1,100Cm ^-1, and the peak area derived from the SO ₄ group stretching vibration .
The ratio of the peak area derived from the SO ₄ group stretching vibration to the peak area derived from the OH group stretching vibration is calculated by dividing the peak areas derived from the peak areas derived from the SO ₄ group stretching vibration OH group stretching vibration can do.

  The cement admixture of the present invention can be used with various hydraulic materials to prepare hydraulic compositions. In particular, the cement admixture of the present invention can be used together with an alkaline hydraulic substance even though it is acidic. In general, when a hydraulic composition is prepared using an acidic cement admixture together with an alkaline hydraulic substance, the storage stability tends to decrease. However, the cement admixture of the present invention is used together with an alkaline hydraulic substance. Even if the hydraulic composition used is prepared, the storage stability is unlikely to decrease. Therefore, the hydraulic composition prepared using the cement admixture of the present invention can be stored for a long time without performing a special storage method, construction method or handling method. Moreover, this hydraulic composition can form a hardened | cured material which has super-fast hardness and high intensity | strength. Therefore, construction can be simplified by using this hydraulic composition.

The hydraulic substance used in the hydraulic composition is not particularly limited. For example, various portland cements such as normal, early strong, moderate heat, low heat, white, etc .; manufactured from municipal waste incineration ash and sewage sludge incineration ash as raw materials Eco-cement to be used; mixed cement containing blast furnace slag, silica fume, limestone, fly ash, gypsum and the like.
Although it does not specifically limit as pH of a hydraulic substance, Preferably it exceeds 7, More preferably, it is 8 or more, More preferably, it is 10 or more.

  The hydraulic composition can contain known additives that can be generally blended in the hydraulic composition as long as the effects of the present invention are not impaired. Although it does not specifically limit as an additive, A rust preventive agent, a coloring agent, a polymer, a fiber, a fluidizing agent, a neutralization inhibitor, a waterproofing agent, a thickener, a waterproofing agent, a retarder, an early strengthening agent, an accelerator , Water reducing agent, high performance (AE) water reducing agent, foaming agent, foaming agent, AE agent, drying shrinkage reducing agent, quick setting agent, swelling agent, cold resistance promoter, efflorescence inhibitor, alkali aggregate reaction inhibitor, Examples include black unevenness reducing agents and environmental purification admixtures. These additives can be used alone or in combination of two or more.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples without departing from the gist thereof.
<Preparation of Al ₂ O ₃ -SO ₃ compounds>
The following substances were used as raw materials.
Al ₂ O ₃ source: Aluminum hydroxide, reagent, purity 99%
SO ₃ source: sulfuric acid, reagent, purity 99%
Solvent: Pure water Al ₂ O ₃ source and SO ₃ source and a solvent 2: 3 were mixed with 10 molar ratio of the mixture by reaction by heating to each temperature shown in Table 1, Al ₂ O ₃ —SO ₃ -based compounds (No. 1 to 15) were prepared.
The Al ₂ O ₃ —SO ₃ -based compound prepared above was evaluated for X-ray diffraction, ignition loss, true density, BET specific surface area, solid ²⁷ Al-NMR, and FT-IR.

X-ray diffraction was measured using a Rigaku Multi-Flex. The measurement was performed under the condition of 2θ: 5 ° to 60 °, 5 ° / min with tube voltage-tube current of 40 KV-40 mA. Moreover, PDXL was used for the analysis software. In the evaluation of X-ray diffraction, if the X-ray diffraction spectrum was broad, it was determined to be amorphous, and the others were determined to be crystalline.
The ignition loss was calculated based on the above formula (1) by measuring the weight loss when ignited at 500 ° C. for 1 hour using a muffle furnace manufactured by Isuzu.
The true density was measured using a dry automatic densimeter (Accumic II 1340) manufactured by Micromeritics.
The BET specific surface area was measured by a BET single point method using a monosorb (MONOSORB) manufactured by Yuasa Ionics.

The solid ²⁷ Al-NMR was performed under the above-described conditions using a superconducting nuclear magnetic resonance apparatus (ECX-400) manufactured by JEOL Ltd., and the peak chemical shift and half width were measured.
FT-IR was measured using Frontier manufactured by PerkinElmer. In the measurement, after performing background measurement using a single reflection type ATR, a sample was set and the surface of the sample was measured at 16 scanning times. The measurement results are output with the vertical axis (Y axis) as absorbance and the horizontal axis as wave number, and the peak area (integral value) derived from OH group stretching vibration and the peak area (integration value) derived from SO ₄ group stretching vibration. Calculation was performed using analysis software (Spectraum manufactured by Perkin Elmer).
The results of the above evaluations are shown in Table 1.

Next, a hydraulic composition was prepared using the Al ₂ O ₃ —SO ₃ compound prepared above. Specifically, normal Portland cement (pH 14, industrial product) is used as the hydraulic substance, and ₃ parts by mass of Al ₂ O ₃ —SO ₃ compound is mixed with 100 parts by mass of the hydraulic substance and mixed. A hydraulic composition was obtained. Then, 50 mass parts of water (tap water) was further blended and mixed with this hydraulic composition, and a setting test and measurement of compressive strength were performed.
The setting test and the measurement of the compressive strength were performed in accordance with JIS R5201 “Physical testing method for cement”. In the setting test, the initial and final times of setting were measured. The compressive strength was measured at the age of 1 day, 7 days, and 28 days, starting from when water was added.
Table 2 shows the results of the above evaluations.

As shown in Table 2, a hydraulic composition using an Al ₂ O ₃ —SO ₃ compound (No. _{3 to} 13) that is amorphous and has an ignition loss of 5 to 40% by mass is as follows: Compared to hydraulic compositions using Al ₂ O ₃ —SO ₃ -based compounds (No. 1-2 and 14-15) that do not have such properties, the setting time is faster and the compressive strength is equivalent or higher. Met.

  Next, after preparing a hydraulic composition in the same manner as above, it was sealed in a plastic bag and stored for one month under conditions of a temperature of 20 ° C. and a humidity of 60%. Thereafter, in the same manner as described above, water (tap water) was further blended and mixed with the hydraulic composition, and a setting test and measurement of compressive strength were performed. The results are shown in Table 3.

As shown in Table 3, a hydraulic composition using an Al ₂ O ₃ —SO ₃ -based compound (No. _{3 to} 13) that is amorphous and has an ignition loss of 5 to 40% by mass, Even after storage for one month, almost no change was observed in the setting time and compressive strength, confirming excellent storage stability. On the other hand, some of the hydraulic compositions (No. 1-2) using Al ₂ O ₃ —SO ₃ -based compounds that do not have this property have a long setting time and are stable in storage. Was not enough.

  Next, after preparing a hydraulic composition in the same manner as above, it was sealed in a plastic bag, and stored under the conditions of a temperature of 20 ° C. and a humidity of 60% for the period shown in Table 4. Thereafter, in the same manner as above, water (tap water) was further blended into the hydraulic composition and mixed, and a setting test was performed. The results are shown in Table 4.

As shown in Table 4, the hydraulic composition using an Al ₂ O ₃ —SO ₃ -based compound (No. _{3 to} 13) that is amorphous and has an ignition loss of 5 to 40% by mass, Even after 12 months of storage, there was almost no change in the setting time, confirming excellent storage stability.
On the other hand, No. 1 using an Al ₂ O ₃ —SO ₃ based compound which does not have this property. The hydraulic composition No. 1 had good setting properties after 1 day of storage, but the setting properties decreased after 1 month of storage, and the same tendency was observed at 6 months and 12 months. No. 2 using an Al ₂ O ₃ —SO ₃ compound that does not have this property. The hydraulic composition of No. 2 showed the same tendency. Furthermore, No. 1 using an Al ₂ O ₃ —SO ₃ based compound not having this property. Although the hydraulic compositions of Nos. 14 and 15 had good storage properties, it was confirmed that the setting time was long even after storage for 1 day.

  As can be seen from the above results, according to the present invention, it is difficult to reduce the storage stability even if blended in advance with the hydraulic composition, and the hydraulic composition has a super-fast hardness and the strength of the cured product is high. A cement admixture that can be provided can be provided. Further, according to the present invention, it is possible to provide a hydraulic composition that is less likely to be deteriorated in storage stability, has super fast hardness, and has a high strength of a cured product.

Claims (7)

A cement admixture containing aluminum sulfate hydrate which is amorphous and has a weight loss of 5 to 40% by mass when ignited at 500 ° C. The cement admixture according to claim 1, wherein the true density of the aluminum sulfate hydrate is 1.9 to 2.3 g / cm ³ . The cement admixture according to claim 1 or 2, wherein the aluminum sulfate hydrate has a BET specific surface area of 5 m ² / g or less. The aluminum sulfate hydrate has a peak at a chemical shift of −0.51 to −23.21 ppm in a spectrum obtained by solid-state ²⁷ Al-NMR, and its half-value width is 5 ppm or more. The cement admixture according to any one of 3 above. In the spectrum obtained by FT-IR, the aluminum sulfate hydrate has a ratio of a peak area derived from SO ₄ group stretching vibration to a peak area derived from OH group stretching vibration of 0.2 to 3.0. The cement admixture according to any one of claims 1 to 4.   The cement admixture according to any one of claims 1 to 5, which is used together with an alkaline hydraulic substance.   A hydraulic composition comprising the cement admixture according to any one of claims 1 to 6 and an alkaline hydraulic substance.