JP2019043805A - Cement admixture, and hydraulic composition - Google Patents

Abstract

To provide a cement admixture that hardly causes deterioration of storage stability of a hydraulic composition when mixed into the composition beforehand, has a super quick hardening property, and can yield a hydraulic composition capable of forming a hardened body of high strength, and a hydraulic composition that resists deteriorating of storage stability, has a super quick hardening property, and is capable of yielding a hardened body of high strength.SOLUTION: The cement admixture comprises an amorphous ALO-SObased compound showing a weight loss of 5 to 40 mass% upon being strongly heated at 500°C. The hydraulic composition comprises the cement admixture and an alkaline hydraulic substance.SELECTED DRAWING: None

Description

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

  In recent years, various performances have been required for hydraulic compositions in the field of civil engineering, construction and the like. 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, conversion of materials into one material, 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, to make the premix, etc., and in fact, various hydraulic compositions having super rapid hardness are proposed. (For example, patent documents 1-3). Also, recently, with the further improvement of the simplification of construction and the response to new applications, the performance required for hydraulic compositions is also increasing more and more.

Unexamined-Japanese-Patent No. 3-12350 Unexamined-Japanese-Patent No. 1-230455 Unexamined-Japanese-Patent No. 11-139859 gazette

A cement admixture is blended in the hydraulic composition for the purpose of improving various characteristics such as the curing rate. As the cement admixture, conventionally, alkaline ones have been used, but from the viewpoint of safety, it is desirable to use acidic ones.
However, since hydraulic materials such as cement are strongly alkaline, they are difficult to combine with acidic cement admixtures, and there is a problem that hydraulic compositions having desired properties can not be obtained. In fact, when a conventional acidic cement admixture suitable for improving the curing rate and making into a premix is added to the hydraulic composition, the storage stability of the hydraulic composition, the strength of the cured product, and the like are reduced.

The present invention has been made to solve the problems as described above, and it is difficult to reduce the storage stability even if it is blended in advance in the hydraulic composition, and it has super rapid hardness and the strength of the cured product is An object of the present invention is to provide a cement admixture capable of providing a highly hydraulic composition.
Another object of the present invention is to provide a hydraulic composition in which the storage stability is unlikely to be reduced, the ultra-high-speed curing is achieved, and the strength of the cured product is high.

As a result of intensive studies to solve the problems as described above, the present inventors found that, despite the fact that the Al ₂ O ₃ -SO ₃ compounds having specific properties are acidic, cement admixtures As a result, the present invention has been completed.
That is, the present invention is a cement admixture containing an Al ₂ O ₃ —SO ₃ based compound which is amorphous and has a weight loss of 5 to 40% by mass when ignited at 500 ° C.
Further, the present invention is a hydraulic composition comprising the cement admixture and an alkaline hydraulic material.

According to the present invention, a cement admixture capable of providing a hydraulic composition having super fast-hardening and high strength of a cured body, while being difficult to reduce storage stability even when previously compounded in a hydraulic composition Can be provided.
Further, according to the present invention, it is possible to provide a hydraulic composition which has an ultra-fast-hardening property and a high strength of a cured body, while the storage stability is hardly reduced.

The cement admixture of the present invention contains an Al ₂ O ₃ -SO ₃ based compound. The Al ₂ O ₃ -SO ₃ -based 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 compound is not amorphous, it is difficult to be premixed with a hydraulic material exhibiting strong alkalinity such as cement, and storage of the hydraulic composition is possible even if it can be premixed. Stability is reduced.
Here, it can be judged by X-ray diffraction analysis whether the Al ₂ O ₃ -SO ₃ based compound is amorphous. Specifically, if the X-ray diffraction spectrum of the Al ₂ O ₃ -SO ₃ -based compound is broad, it can be judged to be amorphous.

In addition, when the weight loss at the time of ignition at 500 ° C. is less than 5% by mass, the curing speed of the hydraulic composition decreases. On the other hand, when the weight loss at the time of firing at 500 ° C. exceeds 40% by mass, the storage stability of the hydraulic composition is reduced. The weight loss when ignited at 500 ° C. is preferably 10 to 40% by mass from the viewpoint of stably improving the curing speed and storage stability of the hydraulic composition.
Here, in the present specification, the loss on ignition at 500 ° C. (loss on ignition) means the loss on ignition of the Al ₂ O ₃ —SO ₃ compound at 500 ° C. for 1 hour, It is calculated by the following equation (1).
Ignition weight loss = (m-m ') / m × 100 (1)
m: Mass of Al ₂ O ₃ -SO ₃ series compound before ignition m ': Mass of Al ₂ O ₃ -SO ₃ series compound after ignition

The Al ₂ O ₃ -SO ₃ -based 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. As the manufacturing method, the method is not particularly limited, for example, the method of heat treatment after mixing Al ₂ O ₃ source and SO ₃ source, is directly chemically reacting Al ₂ O ₃ source and SO ₃ source, Al ₂ O It is possible to use a method in which the _three sources and the SO ₃ source are introduced into a solvent such as pure water and mixed and then chemically reacted. In these methods, by controlling the production conditions, it is possible to obtain an Al ₂ O ₃ —SO ₃ -based compound having the above-mentioned properties. 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, the Al ₂ O ₃ -SO ₃ based compound is controlled by controlling conditions such as reaction temperature. You can adjust the weight loss on ignition. The reaction temperature at this time can not be uniquely defined because it varies depending on the type and blending ratio of the Al ₂ O ₃ source and the SO ₃ source used, but is typically 70 ° C. to 280 ° C.

The Al ₂ O ₃ source is not particularly limited, and aluminum sulfate, aluminate, and 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 hydroxide hydroxide, synthetic hydrotalcite Site, and aluminum metasilicate and the like.

The organic aluminum compound is not particularly limited, and examples thereof include aluminum stearate, aluminum oxalate, aluminum isopropoxide, and aluminum formate.
The aluminum complex is not particularly limited, and examples thereof include tris (8-hydroxyquinolinato) aluminum and the like.
A single species can be used as the Al ₂ O ₃ source, but two or more species may be used in combination. Further, among the various Al ₂ O ₃ sources described above, aluminum sulfate is preferred in view of high solubility in water, low production cost and excellent setting property.

The SO ₃ source is not particularly limited, but in addition to elemental sulfur such as sulfur and sulfur, sulfide, sulfuric acid, sulfate, sulfite, sulfite, thiosulfate, thiosulfate, organic sulfur compounds, etc. Can be used.
Although it does not specifically limit as a sulfide, For example, magnesium sulfide, calcium sulfide, iron sulfide, and phosphorus pentasulfide etc. are mentioned.
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 sulfonic acid derivatives, salts of sulfonic acid derivatives, mercaptan, thiophene, thiophene derivatives, polysulfone, polyether sulfone, and resins such as polyphenylene sulfide.
Although a single species can be used as the SO ₃ source, two or more species may be used in combination. Further, among the various SO ₃ sources described above, sulfates are preferable, and ammonium alum is most preferable, from the viewpoints of high solubility in water, low manufacturing cost, and excellent aggregation.

The Al ₂ O ₃ -SO ₃ based compound used for 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. Is preferred. If the true density is less than 1.9 g / cm ³ , the storage stability of the hydraulic composition may be reduced. On the other hand, if the true density exceeds 2.3 g / cm ³ , the curing speed of the hydraulic composition may be reduced.
Here, the true density of the Al ₂ O ₃ -SO ₃ based compound can be measured using a commercially available densitometer.

The Al ₂ O ₃ -SO ₃ compound used for the cement admixture of the present invention preferably has a BET specific surface area of 5 m ² / g or less, and 3 m ² , from the viewpoint of improving the curing rate of the hydraulic composition. It is more preferable that it is / g or less. 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 time and effort of the pulverization treatment increase, leading to an increase in cost.
Here, the BET specific surface area of the Al ₂ O ₃ -SO ₃ -based compound can be measured using a commercially available BET specific surface area measuring device.

The Al ₂ O ₃ -SO ₃ compounds used in the cement admixture of the present invention have chemical shifts 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 a half width of 5 ppm or more. When the chemical shift of the peak is larger than -0.51 ppm, it is difficult to be premixed with the hydraulic substance, and the storage stability of the hydraulic composition may decrease even if the premix can be achieved. On the other hand, if the chemical shift of the peak is smaller than -23.21 ppm, the effect of improving the curing rate of the hydraulic composition may not be obtained. When the half width is less than 5 ppm, the effect of improving the curing speed and storage stability of the hydraulic composition may not be sufficiently obtained.

Here, solid-state ²⁷ Al-NMR measurement of the Al ₂ O ₃ -SO ₃ -based compound is carried out using a commercially available measuring device, for example, a superconducting nuclear magnetic resonance device “ECX-400” manufactured by Nippon Denshi Co., Ltd. It can be done on condition.
Observation nucleus: ²⁷ Al
Sample tube rotation speed: 10 KHz
Measurement temperature: Room temperature Pulse width: 3.3 μsec (90 ° pulse)
Wait time: 5 seconds External standard: Aluminum nitrate

The Al ₂ O ₃ -SO ₃ based compound used in the cement admixture of the present invention has 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. Preferably, the ratio of the peak area derived from the SO ₄ group stretching vibration to the peak area derived from is 0.2 to 3.0. If the ratio of peak areas is less than 0.2, the effect of improving the curing speed 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 be reduced.

Here, FT-IR (Fourier transform infrared spectroscopy) of the Al ₂ O ₃ -SO ₃ based compound is performed by the ATR method using a commercially available FT-IR apparatus, for example, Frontier manufactured by Perkin Elmer. Can.
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 And 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 together with various hydraulic substances to prepare hydraulic compositions. In particular, the cement admixture according to the present invention can be used together with an alkaline hydraulic substance despite being acidic. In general, when a cementitious composition containing an acid is used together with an alkaline hydraulic substance to prepare a hydraulic composition, the storage stability tends to decrease, but the cement admixture according to the present invention together with an alkaline hydraulic substance Even if the hydraulic composition is prepared, the storage stability hardly decreases. 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, a construction method or a handling method. Moreover, this hydraulic composition can form a hardened | cured material which has super rapid-hardening property and high intensity | strength. Therefore, simplification of construction becomes possible by using this hydraulic composition.

The hydraulic material used for the hydraulic composition is not particularly limited, but, for example, various portland cements such as normal, early strong, moderate heat, low heat, white, etc .; manufactured from municipal waste incineration ash, sewage sludge incineration ash Mixed cement including blast furnace slag, silica fume, limestone, fly ash, gypsum and the like.
The pH of the hydraulic material is not particularly limited, but preferably 7 or more, more preferably 8 or more, and still more preferably 10 or more.

  A hydraulic composition can contain the well-known additive which can be generally mix | blended with a hydraulic composition in the range which does not inhibit the effect of this invention. Although it does not specifically limit as an additive, A rust inhibitor, a coloring agent, a polymer, a fiber, a fluidizer, a carbonization 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, Fastening agent, Swelling agent, Cold weather accelerator, Efflorescence inhibitor, Alkali aggregate reaction inhibitor, Black unevenness reducing agents, environmental purification admixtures, etc. may be mentioned. These additives may be used alone or in combination of two or more.

Hereinafter, the present invention will be more specifically described using examples and comparative examples, but the present invention is not limited to the following examples without departing from the scope of the present invention.
<Preparation of Al ₂ O ₃ -SO ₃ Compound>
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, SO ₃ source and solvent are mixed at a molar ratio of 2: 3: 10, and the mixture is heated to react at each temperature shown in Table 1 to react, Al ₂ O ₃ -SO ₃ based compound (No.1~15) was prepared.
The X-ray diffraction, the loss on ignition, the true density, the BET specific surface area, the solid ²⁷ Al-NMR, and the FT-IR were evaluated for the Al ₂ O ₃ -SO ₃ compounds prepared above.

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

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

Next, to prepare a hydraulic composition with the above prepared Al ₂ O ₃ -SO ₃ compound. Specifically, ordinary portland cement (pH 14, manufactured goods) is used as the hydraulic substance, and ₃ parts by mass of Al ₂ O ₃ -SO ₃ compound is mixed and mixed with 100 parts by mass of the hydraulic substance. A hydraulic composition was obtained. Thereafter, 50 parts by mass of water (tap water) was further blended with this hydraulic composition and mixed, 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 R 5201 "Physical test method of cement". The coagulation test measured the time of initiation and termination of coagulation. In addition, compressive strength was measured at material ages of 1, 7 and 28 days, starting from the time of addition of water.
The results of each of the above evaluations are shown in Table 2.

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

  Next, a hydraulic composition was prepared in the same manner as described above, and the composition was put in a plastic bag and sealed, and stored for one month at a temperature of 20 ° C. and a humidity of 60%. Thereafter, in the same manner as described above, the hydraulic composition was further mixed with water (tap water) and mixed, and the setting test and the measurement of the 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) which is amorphous and has a loss on ignition of 5 to 40% by mass is Almost no change was observed in setting time and compressive strength even after storage for one month, and it was confirmed that the storage stability was excellent. On the other hand, some of the hydraulic compositions (Nos. 1 and 2) using the Al ₂ O ₃ -SO ₃ series compound not having the property have a long setting time, and the storage stability is Was not enough.

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

As shown in Table 4, a hydraulic composition using an Al ₂ O ₃ -SO ₃ based compound (No. _{3 to} 13) which is amorphous and has a loss on ignition of 5 to 40% by mass is Almost no change was observed in the setting time after storage for 12 months, and it was confirmed that the storage stability was excellent.
On the other hand, No. 1 using an Al ₂ O ₃ -SO ₃ series compound not having the above properties. In the hydraulic composition of No. 1, good setting properties were obtained on 1 day of storage, but the setting properties on 1 month of storage decreased, and the same tendency was observed for 6 months and 12 months. In addition, No. 1 using an Al ₂ O ₃ -SO ₃ series compound not having the above properties. The hydraulic composition of 2 showed the same tendency. Furthermore, No. 1 using an Al ₂ O ₃ -SO ₃ series compound not having such properties. Although the hydraulic compositions 14 and 15 had good storability, it was confirmed that setting time is long even on 1 day of storage.

  As can be seen from the above results, according to the present invention, a hydraulic composition which has super fast hardenability and high strength of a cured product, while having reduced storage stability even if it is compounded in advance in the hydraulic composition It is possible to provide a cement admixture that can be provided. Further, according to the present invention, it is possible to provide a hydraulic composition which has an ultra-fast-hardening property and a high strength of a cured body, while the storage stability is hardly reduced.

Claims (7)

A cement admixture containing an Al ₂ O ₃ -SO ₃ based compound 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 a true density of the Al ₂ O ₃ -SO ₃ based compound is 1.9 to 2.3 g / cm ³ . The cement admixture according to claim 1, wherein a BET specific surface area of the Al ₂ O ₃ —SO ₃ based compound is 5 m ² / g or less. The Al ₂ O ₃ -SO ₃ based compound has a peak at a chemical shift of −0.51 to −23.21 ppm and a half width of 5 ppm or more in a spectrum obtained by solid ²⁷ Al-NMR. The cement admixture according to any one of claims 1 to 3. The Al ₂ O ₃ -SO ₃ based compound, in a spectrum obtained by FT-IR, 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 0.2-3. The cement admixture according to any one of claims 1 to 4, which is 0.   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.