Allophane-containing composition and method for producing the same, hydraulic composition and method for producing the same, and cured product and method for producing the same

Abstract

To provide an allophane-containing composition capable of reducing the amount of carbon dioxide generated.SOLUTION: The allophane-containing composition satisfies the following condition (1) or (2): (1) A BET specific surface area of more than 200 m2 / g and a cumulative calorific value accompanying a reaction when the allophane-containing composition is mixed with calcium hydroxide at a mass ratio of 1:3 of 80 to 150 J / g; and (2) A BET specific surface area of 50 to 200 m2 / g and a cumulative calorific value accompanying a reaction when the allophane-containing composition is mixed with calcium hydroxide at a mass ratio of 1:3 of 50 J / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an allophane-containing composition and a method for producing the same, a hydraulic composition and a method for producing the same, and a hardened body and a method for producing the same. [Background technology]

[0002] Cement clinker, which is blended into Portland cement, is produced by burning raw materials in a kiln. This production process generates carbon dioxide. In order to reduce carbon dioxide emissions, attempts have been made to prepare low-carbon hydraulic compositions using inorganic minerals. For example, Patent Document 1 shows that compressive strength can be improved by calcining a mineral containing allophane, which is more readily available than metakaolin, and using this in a hydraulic composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-127724 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a hydraulic composition capable of reducing the amount of carbon dioxide generated and a method for producing the same, a hardened product thereof and a method for producing the same, and an allophane-containing composition capable of reducing the amount of carbon dioxide generated and a method for producing the same. [Means for solving the problem]

[0005] The allophane-containing composition according to one aspect of the present disclosure satisfies the following condition (1) or (2). (1) BET specific surface area is 200m 2 / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m 2 / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more.

[0006] Such an allophane-containing composition exhibits a predetermined range of cumulative heat release associated with its reaction with calcium hydroxide, depending on the range of its BET specific surface area, and therefore exhibits excellent pozzolanic reactivity when used, for example, as a material for a hydraulic composition. Therefore, it can be suitably used in the preparation of hydraulic compositions as a substitute for alkaline activators such as cement clinker. Because this allophane-containing composition contains mineral-derived allophane, it can generate less carbon dioxide than cement clinker and the like. Furthermore, because it can be obtained by firing at a lower temperature than conventional methods, it can generate less carbon dioxide during production. However, the uses and production methods of the allophane-containing composition are not limited.

[0007] A hydraulic composition according to one aspect of the present disclosure contains the allophane-containing composition and an alkaline activator. This hydraulic composition includes an allophane-containing composition that exhibits excellent strength development. Because the allophane-containing composition contains allophane derived from minerals, it can replace an alkaline activator such as cement clinker in the hydraulic composition, thereby reducing the amount of carbon dioxide generated.

[0008] A hardened product according to one aspect of the present disclosure is obtained by hardening the hydraulic composition. Because this hardened product is obtained by hardening the hydraulic composition, it is possible to reduce the amount of carbon dioxide generated.

[0009] A method for producing an allophane-containing composition according to one aspect of the present disclosure includes calcining volcanic ejecta deposits containing allophane at 400 to 750°C. This production method not only results in the production of an allophane-containing volcanic ejecta deposit by calcining at a relatively low temperature of 400 to 750°C, but also exhibits excellent pozzolanic reactivity when used as a material for a hydraulic composition. Therefore, the allophane-containing composition can be suitably used as a substitute for alkaline activators such as cement clinker in the preparation of hydraulic compositions. Because this allophane-containing composition contains mineral-derived allophane, it can generate less carbon dioxide than cement clinker and the like. Furthermore, because the allophane-containing composition is obtained by calcining at a lower temperature than conventional compositions, it can also generate less carbon dioxide.

[0010] A method for producing a hydraulic composition according to one aspect of the present disclosure includes a step of blending at least the allophane-containing composition obtained by the above-described production method with an alkaline activator to obtain a hydraulic composition containing the allophane-containing composition and the alkaline activator. In this method for producing a hydraulic composition, the allophane-containing composition is used as a raw material. By replacing an alkaline activator such as cement clinker with the allophane-containing composition, the amount of carbon dioxide generated can be reduced.

[0011] A method for producing a hardened product according to one aspect of the present disclosure includes at least a step of curing the hydraulic composition obtained by the above-described production method. Since this production method uses the hydraulic composition obtained using the allophane-containing composition, it is possible to reduce the amount of carbon dioxide generated. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a hydraulic composition capable of reducing the amount of carbon dioxide generated and a method for producing the same, as well as a hardened body and a method for producing the same. It is also possible to provide an allophane-containing composition capable of reducing the amount of carbon dioxide generated and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure are described below. However, the following embodiments are merely examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content. In the description, the numerical ranges exemplified as "a to b" are numerical ranges inclusive of a and b, with a as the lower limit and b as the upper limit. The present disclosure also includes cases in which the upper or lower limit of each numerical range is replaced with the upper or lower limit of another numerical range, and cases in which the numerical value of any of the examples is replaced. When multiple materials are exemplified, one of the materials may be used alone, or multiple materials may be used in combination.

[0014] <Allophane-containing composition and method for producing same> The allophane-containing composition contains allophane. Natural allophane is produced by the long-term alteration of volcanic ash and feldspar in volcanic deposits due to weathering and hydrothermal action. Allophane has a particle diameter of several nanometers to several tens of nanometers (e.g., 3.5 to 5.5 nm) and a hollow spherical structure. The outer part of the hollow sphere (shell) is composed of octahedral sheets of Al2O3, and the inner part of the hollow sphere (shell) is composed of tetrahedral sheets of SiO2. The allophane contained in the allophane-containing composition may be a partially altered natural allophane having such a structure. The allophane contained in the allophane-containing composition may be any composition that maintains the allophane skeleton. In this specification, any composition that can be quantified as allophane using the acid-alkali alternating dissolution method described below is considered to be "allophane" even if its structure has been altered. The allophane-containing composition may be a granular composition.

[0015] The allophane content in the allophane-containing composition may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, or 65% by mass or more, from the viewpoint of sufficiently increasing the strength development when used as a raw material for a hydraulic composition. The allophane content in the allophane-containing composition may be 90% by mass or less, or 80% by mass or less, from the viewpoint of ease of acquisition or preparation. The allophane content in this specification is measured by an acid-alkali alternating dissolution method. An example of the range of the allophane content in the allophane-containing composition may be 10 to 90% by mass.

[0016] The allophane-containing composition satisfies the following condition (1) or (2). (1) BET specific surface area is 200m 2 / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m 2 / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more. The cumulative calorific values ​​are all values ​​per gram of a mixture obtained by mixing the allophane-containing composition and calcium hydroxide in a mass ratio of 1:3.

[0017] Hereinafter, an allophane-containing composition whose BET specific surface area and the value of the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 satisfy the ranges specified in (1) above will be referred to as "allophane-containing composition (1)." Furthermore, an allophane-containing composition whose BET specific surface area and the value of the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 satisfy the ranges specified in (2) above will be referred to as "allophane-containing composition (2)." Furthermore, the allophane-containing composition (1) and the allophane-containing composition (2) will be collectively referred to as "allophane-containing composition."

[0018] The BET specific surface area of ​​the allophane-containing composition (1) is set to 220 m from the viewpoint of further increasing the strength development when used as a material for a hydraulic composition. 2 / g or more, 240m 2 / g or more, 260m 2 / g or more, or 270m 2 The BET specific surface area of ​​the allophane-containing composition (1) may be 400 m / g or more from the viewpoint of easy availability. 2 / g or less, 350m 2 / g or less, or 300m 2 / g or less. The BET specific surface area of ​​the allophane-containing composition can be adjusted by changing the grinding conditions and classification conditions. Grinding may be carried out using a conventional grinder, and classification may be carried out using a conventional classifier. The BET specific surface area in this specification is measured by the method described in the Examples.

[0019] The cumulative calorific value (hereinafter sometimes simply referred to as "cumulative calorific value") accompanying the reaction when an allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is measured using a sample prepared by adding an alkaline aqueous solution as a cement-simulating pore solution to a mixture obtained by mixing an allophane-containing composition (calcined product) with calcium hydroxide in a mass ratio of 1:3, as described in the Examples. The composition of the cement-simulating pore solution, the measuring device, and the measuring conditions are as described in the Examples.

[0020] The cumulative calorific value is thought to correlate with the pozzolanic reactivity of the allophane-containing composition when it is used as a material for a hydraulic composition. Therefore, from the viewpoint of further increasing the strength development due to the pozzolanic reaction, the cumulative calorific value of the allophane-containing composition (1) may be 85 J / g or more, 90 J / g or more, or 95 J / g or more. The cumulative calorific value of the allophane-containing composition can be increased, for example, by increasing the calcination temperature to a certain extent when preparing the allophane-containing composition. However, if the calcination temperature is too high, sintering of the particles proceeds, reducing the BET specific surface area and tending to reduce the strength development. From this viewpoint, the cumulative calorific value of the allophane-containing composition (1) may be 140 J / g or less, or 130 J / g or less.

[0021] The amount of Al eluted in the supernatant obtained by blending 20 mL of an aqueous NaOH solution having an NaOH concentration of 3 mol / L with 0.5 g of the allophane-containing composition (1), stirring for 5 hours, and then centrifuging the mixture may be 2000 ppm by mass or more, or 2500 ppm by mass or more. The upper limit of the amount of Al eluted in the supernatant may be 5000 ppm by mass. The amount of Si eluted in the supernatant may be 1000 ppm by mass or more, or 1500 ppm by mass or more. The upper limit of the amount of Si eluted in the supernatant may be 4000 ppm by mass. The total amount of Al and Si eluted in the supernatant may be 3000 ppm by mass or more, or 4000 ppm by mass or more. The total amount of Al and Si eluted in the supernatant may be 9000 ppm by mass or less, or 7000 ppm by mass to 8000 ppm by mass.

[0022] The BET specific surface area of ​​the allophane-containing composition (2) is set to 70 m from the viewpoint of further increasing the strength development when used as a material for a hydraulic composition. 2 / g or more, 100m 2 / g or more, 120m 2 / g, or 130m 2 The BET specific surface area of ​​the allophane-containing composition (2) may be 190 m / g or more. 2 / g or less, or 170m 2 / g or less.

[0023] The cumulative calorific value of the allophane-containing composition (2) may be 55 J / g or more, 60 J / g or more, or 65 J / g or more, from the viewpoint of further increasing the strength development due to the pozzolanic reaction. The cumulative calorific value of the allophane-containing composition can be increased, for example, by increasing the calcination temperature to a certain extent when preparing the allophane-containing composition. However, if the calcination temperature is too high, sintering of the particles will proceed, reducing the BET specific surface area and tending to reduce the strength development. From this viewpoint, the cumulative calorific value of the allophane-containing composition (2) may be 140 J / g or less, 120 J / g or less, or 100 J / g or less.

[0024] The amount of Al eluted in the supernatant obtained by blending 20 mL of an NaOH aqueous solution having an NaOH concentration of 3 mol / L with 0.5 g of the allophane-containing composition (2), stirring for 5 hours, and then centrifuging the mixture may be 1800 ppm by mass or more, or 2200 ppm by mass or more. The upper limit of the amount of Al eluted in the supernatant may be 4500 ppm by mass. The amount of Si eluted in the supernatant may be 1000 ppm by mass or more, or 1500 ppm by mass or more. The upper limit of the amount of Si eluted in the supernatant may be 4000 ppm by mass. The total amount of Al and Si eluted in the supernatant may be 2000 ppm by mass or more, 2500 ppm by mass or more, 3500 ppm by mass or more, or 4000 ppm by mass or more. The total amount of Al and Si eluted in the supernatant may be 9000 ppm by mass or less, 8000 ppm by mass or less, or 7000 ppm by mass or less.

[0025] The SiO2 content in the allophane-containing composition may be 30 to 80 mass%, or 35 to 75 mass%. The Al2O3 content in the allophane-containing composition may be 5 to 45 mass%, or 10 to 40 mass%. The Na2O content in the allophane-containing composition may be 0.1 to 5 mass%, or 0.3 to 4 mass%. The K2O content in the allophane-containing composition may be 0.1 to 5 mass%, or 0.2 to 4 mass%. The R2O content in the allophane-containing composition may be 0.1 to 10 mass%, or 0.4 to 8 mass%. The R2O content in the present disclosure is the alkali content, and is calculated as the Na2O content + 0.658K2O content.

[0026] The allophane-containing composition can replace alkali activators such as cement clinker and Portland cement as a material for hydraulic compositions. By replacing these, the allophane-containing composition can reduce the amount of carbon dioxide generated. Furthermore, when used as a material for hydraulic compositions, the allophane-containing composition can maintain sufficiently high strength development.

[0027] A method for producing an allophane-containing composition includes a step of calcining a volcanic eruption deposit containing allophane at 400 to 750°C. The allophane-containing volcanic eruption deposit (hereinafter sometimes referred to as "deposit") may be a natural product or a natural product whose particle size has been adjusted. The deposit may be a commercially available product or a commercially available product whose particle size has been adjusted. Examples of commercially available products include SEKADO P1 (trade name, manufactured by Shinagawa General Co., Ltd.), Kanuma soil, Satsuma soil, and Kuroboku soil. From the viewpoint of improving the strength development of the allophane-containing composition, the allophane content in the deposit may be 10% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, or 65% by mass or more. From the viewpoint of ease of acquisition or preparation, the allophane content in the deposit may be 90% by mass or less, or 80% by mass or less. As described above, the allophane content is measured by the acid-alkali alternating dissolution method.

[0028] The SiO2 content in the deposit may be 30 to 80 mass%, or 35 to 75 mass%. The Al2O3 content in the deposit may be 5 to 45 mass%, or 10 to 40 mass%. The Na2O content in the deposit may be 0.1 to 5 mass%, or 0.3 to 4 mass%. The K2O content in the deposit may be 0.1 to 5 mass%, or 0.2 to 4 mass%. The R2O content in the deposit may be 0.1 to 10 mass%, or 0.4 to 8 mass%.

[0029] Calcination may be carried out in an air atmosphere using a conventional heating furnace. The calcination temperature of the deposit may be 450°C or higher, 500°C or higher, or 550°C or higher, from the viewpoint of sufficiently increasing the pozzolanic reactivity of the allophane-containing composition. The calcination temperature of the deposit may be 700°C or lower, 650°C or lower, or 600°C or lower, from the viewpoints of suppressing the progress of sintering, maintaining a large BET specific surface area of ​​the allophane-containing composition to increase its reactivity, and further reducing the amount of carbon dioxide generated during calcination. The time for maintaining the calcination temperature within the above-mentioned range may be 0.3 to 6 hours, or 0.5 to 4 hours.

[0030] The allophane-containing composition thus obtained may have the properties described above, and may be, for example, allophane-containing composition (1) or allophane-containing composition (2). Allophane-containing composition (1) can be produced, for example, using SEKADO P-1 manufactured by Shinagawa General Co., Ltd. Allophane-containing composition (2) can be produced, for example, using Kanuma soil manufactured by Akagi Engei Co., Ltd. The descriptions of the allophane-containing composition, allophane-containing composition (1), and allophane-containing composition (2) also apply to the method for producing the allophane-containing composition.

[0031] <Hydraulic composition and method for producing the same> The hydraulic composition contains the above-mentioned allophane-containing composition and an alkaline activator. The hydraulic composition may be in powder form or may further contain water. Hydraulic compositions also include those that have fluidity before hardening. Examples of alkaline activators include cement clinker, Portland cement, tricalcium silicate (3CaO SiO2), slaked lime, and alkali carbonates. The allophane-containing composition does not fall under the category of alkaline activators.

[0032] The hydraulic composition may have an allophane-containing composition content of 5 to 20 parts by mass, or 7 to 15 parts by mass, when the total of the allophane-containing composition and the alkaline activator is 100 parts by mass. This allows for a further reduction in the amount of carbon dioxide generated while sufficiently enhancing strength development. The allophane content relative to the total solid content of the hydraulic composition may be 3 to 15% by mass, 4 to 12% by mass, or 5 to 10% by mass, from the viewpoint of enhancing short-term and long-term strength development in a balanced manner.

[0033] The method for producing a hydraulic composition includes a blending step of blending the allophane-containing composition and the alkaline activator to obtain a hydraulic composition containing the allophane-containing composition and the alkaline activator. In the blending step, water may be added and kneaded. The ratio of water to the alkaline activator (water-binder ratio) may be 30 to 70%, or 40 to 60%. Kneading may be performed using a known mixer. The hydraulic composition obtained in this manner not only generates less carbon dioxide but also exhibits excellent strength development.

[0034] <Hardened body and its manufacturing method> The hardened product is obtained by hardening the hydraulic composition described above. When the hydraulic composition is in powder form, it may be hardened by blending with water and curing. Since this hardened product is obtained using the allophane-containing composition described above as a raw material, it is possible to sufficiently reduce the amount of carbon dioxide generated.

[0035] The method for producing a hardened product includes a step of hardening the hydraulic composition described above. When the hydraulic composition is in powder form, it may be hardened by blending with water and curing. When the hydraulic composition is in slurry form, it may be hardened by curing. This production method uses a hydraulic composition produced using the allophane-containing composition described above, and therefore can reduce the amount of carbon dioxide generated and maintain high compressive strength.

[0036] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. For example, in the above embodiments, the allophane-containing composition is used in a hydraulic composition, but it is not essential that the allophane-containing composition be used in a hydraulic composition, and the allophane-containing composition may be used for other purposes. The present disclosure includes the following embodiments [1] to

[10] .

[0037] [1] An allophane-containing composition that satisfies the following condition (1) or (2): (1) BET specific surface area is 200m 2 / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m 2 / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more. [2] The allophane-containing composition according to [1], in which the total amount of Al and Si eluted is 4000 mass ppm or more when 20 mL of a 3 mol / L aqueous NaOH solution and 0.5 g of the allophane-containing composition are blended and stirred for 5 hours. [3] A hydraulic composition comprising the allophane-containing composition according to [1] or [2] above and an alkali activator. [4] The hydraulic composition according to [3], wherein the content of the allophane-containing composition is 5 to 20 parts by mass when the total of the allophane-containing composition and the alkaline activator is 100 parts by mass. [5] A hardened body obtained by hardening the hydraulic composition according to [4] above. [6] A method for producing an allophane-containing composition, comprising a step of calcining a volcanic eruption deposit containing allophane at 400 to 750°C. [7] The method according to [6], wherein the allophane content in the volcanic ejecta deposit is 50 mass% or more. [8] The method for producing an allophane-containing composition according to [6] or [7], wherein the step of obtaining an allophane-containing composition that satisfies the following condition (1) or (2): (1) BET specific surface area is 200m 2 / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m 2 / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more. [9] A method for producing a hydraulic composition, comprising a step of blending at least the allophane-containing composition obtained by the production method according to any one of [6] to [8] with an alkaline activator to obtain a hydraulic composition containing the allophane-containing composition and the alkaline activator.

[10] A method for producing a hardened product, comprising a step of hardening the hydraulic composition obtained by the method according to [9] above. [Example]

[0038] The present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0039] (Example 1-1) <Analysis of volcanic deposits> SEKADO P-1 (trade name, manufactured by Shinagawa General Co., Ltd.) was prepared as a volcanic ejecta deposit containing allophane. The allophane content of SEKADO P-1 was measured using the acid-alkali alternating dissolution method as follows.

[0040] First, organic matter was removed from SEKADO P-1. Specifically, SEKADO P-1 was sieved through a 0.425 mm sieve. 50 ml of 10% by mass hydrogen peroxide solution was added to the sample that passed through the sieve, and the mixture was heated in a water bath. Next, 20 ml of 30% by mass hydrogen peroxide solution was added, and the mixture was heated in a water bath for 24 hours. After that, a sufficient amount of distilled water was added to the sample, and the aqueous phase was separated by centrifugation (2800 rpm, 6 minutes), and the sample was washed. Washing was performed twice. The washed sample was dried at 105°C for 24 hours.

[0041] Next, the dried sample was subjected to the following series of steps (1) to (7) five times. (1) 50 ml of 8 M hydrochloric acid was added to the sample and shaken for 30 minutes. (2) A sufficient amount of distilled water was added to the sample, and the sample was washed by separating the aqueous phase by centrifugation (2800 rpm, 6 minutes). (3) 50 ml of 0.5 M aqueous sodium hydroxide solution was added to the washed sample, and the sample was heated in a water bath at 60°C for 5 minutes. (4) The aqueous phase was separated by centrifugation (2800 rpm, 6 minutes) and the sample was washed. (5) A sufficient amount of distilled water was added to the sample, and the sample was washed by separating the aqueous phase by centrifugation (2800 rpm, 6 minutes). (6) After washing, the sample was dried at 105°C for 24 hours. (7) After drying, the mass of the sample was measured. By repeating the series of steps (1) to (7) five times, it was confirmed that the mass change of the sample due to leaching had almost completely disappeared. The allophane content was calculated based on the mass loss rate. The allophane content was found to be 72.5 mass%.

[0042] <Preparation and analysis of fired products> SEKADO P1 was heated in a calcination furnace in air to a target temperature of 400°C at a rate of 15°C / min, and calcined for 1 hour after reaching the target temperature. After cooling, the calcined product was removed from the calcination furnace. In this way, the calcined product (allophane-containing composition) of Example 1-1 was obtained. The calcined product was subjected to measurement of the BET specific surface area, the amount of eluted Al and Si, and the cumulative calorific value. The details of each measurement are as follows.

[0043] The BET specific surface area was measured by heating the fired material in a nitrogen gas atmosphere at 105°C for 1 hour to dry it, and then measuring the amount of nitrogen gas adsorption at 77K using the BET multipoint method using a Microtrac-Bel BELSORP MAX X. The BET specific surface area was calculated based on the measurement results. The measurement results are shown in Table 1.

[0044] To measure the amount of Al and Si elution, 20 mL of 3 mol / L NaOH aqueous solution and 0.5 g of the calcined material were mixed at 20°C and stirred at 300 rpm using a stirrer for 5 hours. After stirring, the mixture was centrifuged and the resulting supernatant was analyzed by ICP emission spectroscopy to measure the amount of Al and Si elution. The individual elution amounts and the total elution amount are shown in Table 1.

[0045] The cumulative calorific value was measured using a conduction calorimeter (TA Instruments, TAM Air). The calcined product and calcium hydroxide were mixed in a mass ratio of 1:3 to prepare a mixture. The cement-simulating pore solution was added to this mixture to achieve a liquid-solid ratio of 1.2, and the mixture was mixed with a pencil mixer for 2 minutes to prepare the measurement sample. The cement-simulating pore solution was an alkaline solution prepared by adding sodium hydroxide and potassium hydroxide to ion-exchanged water (NaOH concentration: 0.3 mol / L, KOH concentration: 0.19 mol / L). The reactor temperature was set to 40°C, and the calorific value over two days was measured as the cumulative calorific value. The cumulative calorific value (cumulative calorific value per 1 g of calcined product and calcium hydroxide combined) normalized by the total mass of the calcined product and calcium hydroxide is shown in Table 1.

[0046] (Examples 1-2 to 1-4, Comparative Examples 1-1 to 1-4) The calcined products were prepared and analyzed in the same manner as in Example 1-1, except that the calcination temperature when preparing the calcined products was changed as shown in Table 1. The results are shown in Table 1. Comparative Example 1-1 is the result of analyzing SEKADO P1 without calcination.

[0047] [Table 1]

[0048] Examples 1-1 to 1-4 have a BET specific surface area of ​​250 m 2 / g or more, and the cumulative calorific value was 80 J / g or more. On the other hand, in Comparative Example 1-1, where no calcination was performed, the cumulative calorific value was less than 80 J / g. Furthermore, in Comparative Examples 1-2 to 1-4, where the calcination temperature was 800°C or more, the BET specific surface area was reduced due to the progress of sintering.

[0049] <Preparation of hydraulic composition and hardened product> Ordinary Portland cement (manufactured by UBE Mitsubishi Cement Corporation) was prepared as an alkali activator. This ordinary Portland cement was mixed with the calcined product of each Example and Comparative Example (Comparative Example 1-1 was uncalcined SEKADO P-1) in a mass ratio of 90:10 to prepare a hydraulic composition according to the method described in JIS R 5201:2015, "Physical Testing Methods for Cement." The allophane content in the hydraulic composition was calculated as 72.5% by mass x 0.1 = 7.25% by mass. The prepared hydraulic composition was filled into a 4 cm x 4 cm x 16 cm mold and cured in air for one day. After demolding, the composition was cured in water in a thermostatic chamber at 20°C until it reached a material age of 7 days or 28 days. A hardened product was thus obtained.

[0050] <Compression strength measurement> The compressive strength of each hardened body was measured at 7 days and 28 days. The compressive strength was measured in accordance with the method described in JIS R 5201:2015 "Physical Testing Methods for Cement." The results are shown in Table 2.

[0051] [Table 2]

[0052] As shown in Table 2, Examples 1-1 to 1-4 had higher compressive strengths at both 7 and 28 days than Comparative Example 1-1. Furthermore, Examples 1-1 to 1-4 had compressive strengths equal to or greater than those of Comparative Examples 1-2 to 1-4, which were calcined at high temperatures.

[0053] (Examples 2-1 to 2-5, Comparative Examples 2-1 to 2-3) <Analysis of volcanic deposits> Kanuma soil (manufactured by Akagi Engei Co., Ltd.) was prepared as a volcanic deposit containing allophane. The allophane content of Kanuma soil was measured using the same procedure as for SEKADO P-1 (alternate acid-alkali dissolution method). The result was that the allophane content was 63.2 mass%.

[0054] <Preparation and analysis of fired products> Calcined products were prepared and analyzed in the same manner as in Examples 1-1 to 1-4 and Comparative Examples 1-2 to 1-4, except that Kanuma soil was used instead of SEKADO P-1. The results are shown in Table 3. Comparative Example 2-1 shows the results of analyzing Kanuma soil without calcination.

[0055] [Table 3]

[0056] As shown in Table 3, Examples 2-1 to 2-5 have a BET specific surface area of ​​50 m 2 / g or more, and the cumulative calorific value was 50 J / g or more. On the other hand, in Comparative Example 2-1, where no calcination was performed, the cumulative calorific value was less than 50 J / g. Furthermore, in Comparative Examples 2-2 and 2-3, where the calcination temperature was 900°C or more, the BET specific surface area was reduced due to the progress of sintering.

[0057] <Preparation of hydraulic composition and hardened product, and evaluation of the hardened product> Ordinary Portland cement (manufactured by UBE Mitsubishi Cement Corporation) was prepared as an alkali activator. This ordinary Portland cement was mixed with the fired product of each Example and Comparative Example (Kanuma clay for Comparative Example 2-1) in a mass ratio of 90:10 to prepare hydraulic compositions according to the method described in JIS R 5201:2015, "Physical Testing Methods for Cement." The allophane content in the hydraulic composition was calculated as 63.2% by mass x 0.1 = 6.32% by mass. The prepared hydraulic compositions were filled into a 4 cm x 4 cm x 16 cm mold and cured in air for one day. After demolding, the compositions were cured in water in a thermostatic chamber at 20°C until they reached 7 or 28 days of age. Hardened bodies were thus obtained. The compressive strength of each hardened body at 7 and 28 days was measured using the same procedure as in Example 1-1. The results are shown in Table 4.

[0058] [Table 4]

[0059] As shown in Table 4, it was confirmed that Examples 2-1 to 2-5 were able to increase the compressive strength at 7 days and 28 days in a balanced manner. On the other hand, Comparative Example 2-1, which was not calcined, had a low compressive strength at 7 days. Comparative Example 2-2 also had a low compressive strength at 7 days, and Comparative Example 2-3 had low compressive strengths at 7 days and 28 days.

[0060] (Comparative Example 3) A hardened body was obtained in the same manner as in each Example and Comparative Example, except that no calcined product (allophane-containing composition) was added when preparing the hydraulic composition, i.e., ordinary Portland cement (manufactured by UBE Mitsubishi Cement Corporation) was used as the hydraulic composition. The compressive strength of the hardened body was measured at ages of 7 and 28 days in the same manner as in each Example and Comparative Example. As a result, the compressive strength at age 7 days was 46.7 N / mm 2 The compressive strength at 28 days is 61.7N / mm 2Examples 1-1 to 1-4 exhibited higher compressive strength than when ordinary Portland cement was used. Examples 2-1 to 2-5 also exhibited higher compressive strength at an age of 7 days than when ordinary Portland cement was used.

[0061] (Comparative Examples 4-1 to 4-8) Doragonite HP (trade name, manufactured by Phimatex Corporation, halloysite content: 87% by mass) was prepared as a volcanic ejecta deposit containing halloysite. This volcanic ejecta deposit does not contain allophane. Calcined products were prepared and analyzed in the same manner as in Examples 1-1 to 1-4 and Comparative Examples 1-2 to 1-4, except that this volcanic ejecta deposit was used instead of SEKADO P-1. The results are shown in Table 5. Comparative Example 4-1 shows the results of analyzing Doragonite HP without calcination.

[0062] [Table 5]

[0063] The results in Table 5, similar to those in Tables 1 and 3, show a tendency for the BET specific surface area to decrease as the calcination temperature increases. However, because the original BET specific surface area was smaller than that of the volcanic ejecta deposits containing allophane, the rate of change was not very large. On the other hand, the cumulative heat release rate increased significantly as the calcination temperature increased up to 900°C. This confirmed that the behavior of volcanic ejecta deposits containing allophane and those containing halloysite differs depending on the calcination temperature.

[0064] <Preparation of hydraulic composition and hardened product, and evaluation of the hardened product> Ordinary Portland cement (manufactured by UBE Mitsubishi Cement Corporation) was prepared as an alkali activator. This ordinary Portland cement was mixed with the calcined product of each comparative example (Comparative Example 4-1 was uncalcined Doragonite HP) in a mass ratio of 90:10, and hydraulic compositions were prepared according to the method described in JIS R 5201:2015, "Physical Testing Methods for Cement." The prepared hydraulic compositions were filled into a 4 cm × 4 cm × 16 cm mold and cured in air for one day. After demolding, the compositions were cured in water in a thermostatic chamber at 20°C until they reached 7 or 28 days of age. Hardened bodies were thus obtained. The compressive strength of each hardened body at 7 and 28 days of age was measured using the same procedure as in Example 1-1. The results are shown in Table 6.

[0065] [Table 6]

[0066] Comparing Tables 2 and 4 with Table 6, there was a strong tendency for the compressive strength to increase as the calcination temperature increased for calcined volcanic ejecta deposits containing halloysite. This confirmed that, in the case of volcanic ejecta deposits containing allophane, high compressive strength can be obtained even at low calcination temperatures, whereas in the case of volcanic ejecta deposits containing halloysite, a high calcination temperature is required to obtain high compressive strength.

Claims

1. An allophane-containing composition that satisfies the following condition (1) or (2): (1) BET specific surface area is 200 m ２ / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m ２ / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more.

2. 2. The allophane-containing composition according to claim 1, wherein when 20 mL of a 3 mol / L aqueous NaOH solution and 0.5 g of the allophane-containing composition are blended and stirred for 5 hours, the total amount of Al and Si eluted is 4,000 ppm by mass or more.

3. A hydraulic composition comprising the allophane-containing composition according to claim 1 or 2 and an alkaline activator.

4. 4. The hydraulic composition according to claim 3, wherein the content of the allophane-containing composition is 5 to 20 parts by mass when the total of the allophane-containing composition and the alkaline activator is 100 parts by mass.

5. A hardened product obtained by hardening the hydraulic composition according to claim 4.

6. A method for producing an allophane-containing composition, comprising the step of calcining a volcanic ejecta deposit containing allophane at 400 to 750°C.

7. The method according to claim 6, wherein the allophane content in the volcanic ejecta deposit is 50 mass% or more.

8. The method for producing an allophane-containing composition according to claim 6 or 7, wherein the step obtains an allophane-containing composition that satisfies the following condition (1) or (2): (1) BET specific surface area is 200 m ２ / g or more, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 80 to 150 J / g (2) BET specific surface area is 50 to 200 m ２ / g, and the cumulative heat generated by the reaction when the allophane-containing composition is mixed with calcium hydroxide in a mass ratio of 1:3 is 50 J / g or more.

9. 8. A method for producing a hydraulic composition, comprising a step of blending at least the allophane-containing composition obtained by the production method according to claim 6 or 7 with an alkaline activator to obtain a hydraulic composition containing the allophane-containing composition and the alkaline activator.

10. A method for producing a hardened product, comprising a step of hardening the hydraulic composition obtained by the method according to claim 9.

Images