High-activity superfine calcium-carbon silicate curing cementing material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a high-activity superfine calcium-carbon silicate curing cementing material as well as a preparation method and application thereof. The preparation method of the high-activity superfine calcium-carbon silicate curing cementing material comprises the following steps: (1) uniformly mixing carbide slag, quartz powder and water to obtain mixed slurry; (2) drying the mixed slurry to constant weight to obtain a dry material; (3) calcining the dry material to obtain a calcined product; the calcining temperature is 800 to 1100 DEG C; and (4) grinding the calcined product to obtain the high-activity superfine monocalcium silicate carbon curing cementing material. The high-activity superfine calcium-carbon silicate curing cementing material disclosed by the invention can be prepared at a relatively low calcination temperature and is high in carbonization activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a highly active ultrafine calcium monosilicate carbon solidification cementitious material, a preparation method thereof, and an application thereof. Background Art

[0002] Calcium carbide slag is an industrial waste residue discharged in large quantities during the hydrolysis of calcium carbide (CaC2) to produce acetylene. It is statistically known that 1.2 tons of dry calcium carbide slag is produced per ton of calcium carbide. Calcium carbide slag is usually landfilled or stockpiled. Due to its strong alkaline property, it is easy to cause soil and water pollution, causing great damage to the environment. On the other hand, since the main component of calcium carbide slag is Ca(OH)2, almost no carbon dioxide is emitted during the calcination process, so it can be directly used as a calcareous raw material.

[0003] Environmental problems such as the greenhouse effect caused by the high emissions of carbon dioxide are becoming increasingly severe. The construction industry is one of the industries that produce the most carbon emissions. With the increasing building volume, carbon emission reduction in the construction industry is extremely urgent. Since calcium silicate minerals can react with carbon dioxide to form stable compounds and obtain strength, the production of building materials using carbon dioxide mineralization technology has attracted more and more attention. Calcium silicate minerals include tricalcium silicate, dicalcium silicate, tricalcium disilicate, and calcium monosilicate. As the calcium-silicon ratio decreases, the calcination temperature of these calcium silicate minerals and the emitted carbon dioxide also decrease. Therefore, calcium monosilicate has great potential in carbon dioxide mineralized building materials.

[0004] Calcium monosilicate usually has two crystal forms, a low-temperature type and a high-temperature type. Among them, the low-temperature type calcium monosilicate (the calcination temperature is usually 1000 - 1100 °C) has low carbonation activity. Usually, it needs to be transformed into the high-temperature type calcium monosilicate (the calcination temperature is usually 1200 - 1300 °C) to improve its carbonation activity, but this requires a high calcination temperature. How to improve the carbonation activity of low-temperature type calcium monosilicate is of great significance for producing building materials through carbon dioxide mineralization technology, reducing carbon dioxide emissions, and realizing carbon dioxide sequestration. Summary of the Invention

[0005] The purpose of the present invention is to provide a highly active ultrafine calcium monosilicate carbon solidification cementitious material, a preparation method thereof, and an application thereof, which helps to solve or improve the problem of low carbonation activity of low-temperature type calcium monosilicate in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a highly active ultra-fine calcium monosilicate carbon solidified cementitious material, comprising the following steps: (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry; (2) Dry the mixed slurry to constant weight to obtain a dry material; (3) Calcinate the dry material to obtain a calcined product; the calcination temperature is 800 - 1100 °C; (4) Grind the calcined product to obtain the highly active ultra-fine calcium monosilicate carbon solidified cementitious material.

[0007] Preferably, in step (1), the calcium-silicon ratio of the carbide slag to the quartz powder is (1 - 2):1.

[0008] Preferably, in step (1), the water-solid ratio is (5 - 10):1.

[0009] Preferably, in step (3), the calcination time is 1 - 2 h.

[0010] Preferably, in step (4), the particle size of the obtained highly active ultra-fine calcium monosilicate carbon solidified cementitious material is ≤50 μm.

[0011] The present invention also provides a highly active ultra-fine calcium monosilicate carbon solidified cementitious material, which adopts the following technical solutions: A highly active ultra-fine calcium monosilicate carbon solidified cementitious material, which is prepared by the method described above.

[0012] Preferably, the mineral composition of the highly active ultra-fine calcium monosilicate carbon solidified cementitious material includes low-temperature calcium monosilicate, and the grain size of the low-temperature calcium monosilicate is <70 nm.

[0013] The present invention also provides a preparation method of a carbonized product, which adopts the following technical solutions: A preparation method of a carbonized product, comprising the following steps: I. Mix the highly active ultra-fine calcium monosilicate carbon solidified cementitious material described above with water evenly and place it in a mold, and form it to obtain a test block; II. Place the test block in a reaction kettle, introduce a gas containing CO2, and carry out pressure carbonization to obtain the carbonized product.

[0014] Preferably, in step I, the amount of water used is 5 wt% - 10 wt% of the highly active ultra-fine calcium monosilicate carbon solidified cementitious material; the forming pressure is 4 - 6 MPa, and the pressure is maintained for 1 min under the forming pressure to obtain the test block; in step II, the pressure during pressure carbonization is 0.1 - 0.2 MPa.

[0015] The present invention also provides a carbonized product, which adopts the following technical solutions: A carbonized product, which is prepared by the method described above.

[0016] Beneficial effects:

[0017] The highly active ultrafine low-temperature type calcium monosilicate prepared by the method of the present invention has a grain size much smaller than that of the calcium monosilicate prepared by traditional calcination, and a larger specific surface area; the smaller grain size and the larger specific surface area can provide more reaction sites for the carbonization reaction; in addition, the method of the present invention can realize the preparation of the highly active ultrafine low-temperature type calcium monosilicate at a lower calcination temperature. The highly active ultrafine calcium monosilicate carbon solidification cementitious material of the present invention can be prepared at a lower calcination temperature, which helps to reduce energy consumption.

[0018] The highly active ultrafine calcium monosilicate carbon solidification cementitious material of the present invention has high carbonization activity, which helps to shorten the carbonization time; and the compressive strength after carbonization is significantly improved.

[0019] The highly active ultrafine calcium monosilicate carbon solidification cementitious material of the present invention has the potential to be applied at a lower carbon dioxide concentration, which is more conducive to practical industrial applications. Description of the Drawings

[0020] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. Among them:

[0021] Figure 1 It is a physical diagram of the carbonized products of Examples 1-4 and Comparative Examples 1-4 of the present invention.

[0022] Figure 2 It is the XRD pattern of the highly active ultrafine calcium monosilicate carbon solidification cementitious material of Examples 1-8 of the present invention;

[0023] Figure 3 It is the XRD pattern of the highly active ultrafine calcium monosilicate carbon solidification cementitious material of Examples 9-16 of the present invention;

[0024] Figure 4 It is the XRD pattern of the carbon solidification cementitious material of Comparative Examples 1-4. Detailed Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0026] The present invention will be described in detail below with reference to the embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0027] In view of the problems of low carbonation activity and poor hardening performance of current low-temperature calcium monosilicate, the present invention provides a preparation method of a high-activity ultrafine calcium monosilicate carbon-cured cementitious material.

[0028] The preparation method of the high-activity ultrafine calcium monosilicate carbon-cured cementitious material according to the embodiment of the present invention includes the following steps: (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry; (2) Dry the mixed slurry to a constant weight to obtain a dry material; (3) Calcinate the dry material to obtain a calcined product; the calcination temperature is 800-1100 °C (for example, 800 °C, 900 °C, 1000 °C or 1100 °C); (4) Grind the calcined product to obtain a high-activity ultrafine calcium monosilicate carbon-cured cementitious material. Among them, if the calcination temperature is too low, the temperature for forming the phase change of calcium monosilicate cannot be reached, and calcium monosilicate minerals cannot be formed; if the calcination temperature is too high, the crystal grain size of calcium monosilicate will become larger, the specific surface area will become smaller, and the carbonation activity of calcium monosilicate will be reduced.

[0029] The calcium-containing raw material used in the present invention is industrial solid waste carbide slag, which reduces the use cost; burning it into a calcium monosilicate carbon-cured cementitious material is beneficial to reducing the firing temperature and reducing the firing energy consumption; in addition, this high-activity calcium monosilicate has a fast strength growth after carbonation, high hardening performance, and has the potential to be applied under low-concentration carbon dioxide, which is more conducive to industrial practical applications.

[0030] In the high-activity ultrafine calcium monosilicate carbon-cured cementitious material prepared by the method of the present invention, the crystal grain size of calcium monosilicate is much smaller than that of calcium monosilicate prepared by traditional calcination (the minimum crystal grain size can be about 20 nm), and the specific surface area is larger; the smaller crystal grain size and the larger specific surface area can provide more reaction sites for the carbonation reaction, making the low-temperature calcium monosilicate in the high-activity ultrafine calcium monosilicate carbon-cured cementitious material prepared by the method of the present invention have better carbonation activity (even better than that of high-temperature calcium monosilicate).

[0031] In a preferred embodiment of the preparation method of the high-activity ultrafine calcium monosilicate carbon-cured cementitious material of the present invention, in step (1), the calcium-silicon ratio of carbide slag to quartz powder is (1-2):1 (for example, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2:1). Among them, the calcium-silicon ratio is calculated based on the calcium oxide (CaO) content in the carbide slag. The calcium-silicon ratio of carbide slag to quartz powder cannot be too high. If the calcium-silicon ratio of the two is too high, the calcium oxide content in the clinker after calcination will be relatively high, resulting in expansion and cracking after carbonation; when the calcium-silicon ratio of carbide slag to quartz powder is too low, the content of calcium monosilicate formed will be relatively low, resulting in a decline in mechanical properties.

[0032] Preferably, when the calcium-silicon ratio of carbide slag to quartz powder is 1.5:1, the calcination temperature in step (3) is 900 - 1100 °C (for example, 900 °C, 950 °C, 1000 °C, 1050 °C or 1100 °C). When the calcium-silicon ratio of carbide slag to quartz powder is 1.5:1, if the calcination temperature is too low, the content of calcium oxide in the product will be too high, and during the subsequent carbonization process, problems such as expansion and cracking are likely to occur.

[0033] Preferably, when the calcium-silicon ratio of carbide slag to quartz powder is 2:1, the calcination temperature in step (3) is 1100 °C.

[0034] Most preferably, the calcium-silicon ratio of carbide slag to quartz powder is 1:1.

[0035] In a preferred embodiment of the preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the present invention, in step (1), the water-solid ratio is (5 - 10):1 (for example, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1). When the water-solid ratio is relatively low, carbide slag and quartz powder cannot be fully stirred and evenly mixed, resulting in inconsistent local mineral phases in the calcined clinker blocks; when the water-solid ratio is too high, higher energy consumption is required during the drying process.

[0036] In a preferred embodiment of the preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the present invention, in step (3), the calcination time is 1 - 2 h (for example, 1 h, 1.25 h, 1.5 h, 1.75 h or 2 h). Among them, too short a calcination time will lead to incomplete reactions and affect the purity of calcium silicate monocarbon.

[0037] In a preferred embodiment of the preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the present invention, in step (4), the particle size of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material obtained by grinding is ≤ 50 μm.

[0038] The present invention also provides a highly active ultra-fine calcium silicate monocarbon solidified cementitious material, and the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the embodiments of the present invention is prepared by the method described above.

[0039] In a preferred embodiment of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the present invention, the mineral composition of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material includes low-temperature calcium silicate monocarbon; the grain size of low-temperature calcium silicate monocarbon is < 70 nm.

[0040] Preferably, the mineral composition of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of the present invention also includes crystalline CSH and amorphous phases (including amorphous CSH and calcium silicate monocarbon, etc.).

[0041] Preferably, in the mineral composition of the highly active ultrafine calcium monosilicate carbon-curing cementitious material of the present invention, the content of calcium oxide is less than 5%. Among them, if the content of calcium oxide in the mineral composition of the highly active ultrafine calcium monosilicate carbon-curing cementitious material of the present invention is too high, problems such as expansion and cracking are likely to occur during the subsequent carbonization process.

[0042] The present invention also provides a preparation method of a carbonized product. The preparation method of the carbonized product according to the embodiments of the present invention includes the following steps: I. Mix the above-mentioned highly active ultrafine calcium monosilicate carbon-curing cementitious material with water evenly and place it in a mold, and form it to obtain a test block; II. Place the test block in a reaction kettle, introduce a gas containing CO2, and carry out pressure carbonization to obtain a carbonized product.

[0043] In a preferred embodiment of the preparation method of the carbonized product of the present invention, in step I, the amount of water used is 5wt%-10wt% of the highly active ultrafine calcium monosilicate carbon-curing cementitious material (for example, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%); the forming pressure is 4-6MPa (for example, 4MPa, 4.5MPa, 5MPa, 5.5MPa or 6MPa), and keep the pressure for 1 minute under the forming pressure to obtain a test block; in step II, the pressure during pressure carbonization is 0.1-0.2MPa (for example, 0.1MPa, 0.12MPa, 0.14MPa, 0.16MPa, 0.18MPa or 0.2MPa). Among them, too high forming pressure will make the test block too dense, affecting the diffusion of carbon dioxide inside the test block, resulting in insufficient carbonization and affecting the mechanical properties of the hardened body; too low forming pressure will affect the connection between carbonization products. Since the internal structure is relatively loose, the porosity will increase after carbonization, resulting in a decrease in strength; the pressure of carbon dioxide during carbonization is also an important influencing factor. At a lower pressure of carbon dioxide, the solubility may not be sufficient to support the full carbonization reaction, while a higher carbon dioxide pressure will cause calcium carbonate to precipitate rapidly, fill the pores inside the test block, and prevent carbon dioxide from further diffusing into the interior, resulting in a decrease in strength.

[0044] The present invention also provides a carbonized product, and the carbonized product according to the embodiments of the present invention is prepared by the method described above.

[0045] The highly active ultrafine calcium monosilicate carbon-curing cementitious material of the present invention, its preparation method and application will be described in detail below through specific examples.

[0046] The sources of the main raw materials used in the following examples:

[0047] The carbide slag used in the following examples is taken from Henan Jiyuan Lianchuang Chemical Co., Ltd., and the chemical composition of the raw material is shown in Table 1 below; the quartz powder uses amorphous silica with a purity of more than 99.99%.

[0048] Table 1 Chemical composition of carbide slag

[0049]

[0050] Example 1

[0051] The preparation method of the high-activity ultrafine calcium silicate monocarbon solidified cementitious material in this example includes the following steps:

[0052] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 5:1);

[0053] (2) Dry the mixed slurry to constant weight to obtain dry materials;

[0054] (3) Calcinate the dry materials (the calcination temperature is 800 °C and the calcination time is 2 h) to obtain calcined products;

[0055] (4) Grind the calcined products to obtain the high-activity ultrafine calcium silicate monocarbon solidified cementitious material (particle size ≤ 50 μm) in this example.

[0056] Example 2

[0057] The preparation method of the high-activity ultrafine calcium silicate monocarbon solidified cementitious material in this example includes the following steps:

[0058] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 5:1);

[0059] (2) Dry the mixed slurry to constant weight to obtain dry materials;

[0060] (3) Calcinate the dry materials (the calcination temperature is 900 °C and the calcination time is 2 h) to obtain calcined products;

[0061] (4) Grind the calcined products to obtain the high-activity ultrafine calcium silicate monocarbon solidified cementitious material (particle size ≤ 50 μm) in this example.

[0062] Example 3

[0063] The preparation method of the high-activity ultrafine calcium silicate monocarbon solidified cementitious material in this example includes the following steps:

[0064] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 5:1);

[0065] (2) Dry the mixed slurry to constant weight to obtain dry materials;

[0066] (3) Calcine the dry material (calcination temperature is 1000 °C, calcination time is 2 h) to obtain a calcined product;

[0067] (4) Grind the calcined product to obtain the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0068] Example 4

[0069] The preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example includes the following steps:

[0070] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 5:1);

[0071] (2) Dry the mixed slurry to constant weight to obtain a dry material;

[0072] (3) Calcine the dry material (calcination temperature is 1100 °C, calcination time is 2 h) to obtain a calcined product;

[0073] (4) Grind the calcined product to obtain the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0074] Example 5

[0075] The preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example includes the following steps:

[0076] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1.5:1, and the water-solid ratio is 5:1);

[0077] (2) Dry the mixed slurry to constant weight to obtain a dry material;

[0078] (3) Calcine the dry material (calcination temperature is 800 °C, calcination time is 2 h) to obtain a calcined product;

[0079] (4) Grind the calcined product to obtain the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0080] Example 6

[0081] The preparation method of the highly active ultra-fine calcium silicate monocarbon solidified cementitious material of this example includes the following steps:

[0082] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1.5:1, and the water-solid ratio is 5:1);

[0083] (2) Dry the mixed slurry to a constant weight to obtain dry materials;

[0084] (3) Calcinate the dry materials (calcination temperature: 900 °C, calcination time: 2 h) to obtain a calcined product;

[0085] (4) Grind the calcined product to obtain the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0086] Example 7

[0087] The preparation method of the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example includes the following steps:

[0088] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 2:1, and the water-solid ratio is 5:1);

[0089] (2) Dry the mixed slurry to a constant weight to obtain dry materials;

[0090] (3) Calcinate the dry materials (calcination temperature: 800 °C, calcination time: 2 h) to obtain a calcined product;

[0091] (4) Grind the calcined product to obtain the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0092] Example 8

[0093] The preparation method of the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example includes the following steps:

[0094] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 3:1);

[0095] (2) Dry the mixed slurry to a constant weight to obtain dry materials;

[0096] (3) Calcinate the dry materials (calcination temperature: 800 °C, calcination time: 2 h) to obtain a calcined product;

[0097] (4) Grind the calcined product to obtain the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0098] Example 9

[0099] The preparation method of the highly active ultrafine calcium monosilicate carbon solidified cementitious material of this example includes the following steps:

[0100] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 10:1);

[0101] (2) Dry the mixed slurry to constant weight to obtain dry materials;

[0102] (3) Calcinate the dry materials (calcination temperature is 800 °C, and the calcination time is 2 h) to obtain a calcined product;

[0103] (4) Grind the calcined product to obtain the high-activity ultra-fine calcium silicate monocarbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0104] Example 10

[0105] The preparation method of the high-activity ultra-fine calcium silicate monocarbon solidified cementitious material of this example includes the following steps:

[0106] (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry (the calcium-silicon ratio of carbide slag to quartz powder is 1:1, and the water-solid ratio is 5:1);

[0107] (2) Dry the mixed slurry to constant weight to obtain dry materials;

[0108] (3) Calcinate the dry materials (calcination temperature is 800 °C, and the calcination time is 1 h) to obtain a calcined product;

[0109] (4) Grind the calcined product to obtain the high-activity ultra-fine calcium silicate monocarbon solidified cementitious material of this example (particle size ≤ 50 μm).

[0110] Example 11

[0111] The difference between this example and Example 5 is only that: the calcination temperature is 1100 °C; the rest are the same as Example 5.

[0112] Example 12

[0113] The difference between this example and Example 7 is only that: the calcination temperature is 1100 °C; the rest are the same as Example 7.

[0114] Example 13

[0115] The difference between this example and Example 5 is only that: the water-solid ratio is 3:1; the rest are the same as Example 5.

[0116] Example 14

[0117] The difference between this example and Example 7 is only that: the water-solid ratio is 3:1; the rest are the same as Example 7.

[0118] Example 15

[0119] The difference between this example and Example 5 is only that: the calcination time is 1 h; the rest are the same as in Example 5.

[0120] Example 16

[0121] The difference between this example and Example 7 is only that: the calcination time is 1 h; the rest are the same as in Example 7.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is only that: step (3) is omitted; the rest are the same as in Example 1.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is only that: the calcination temperature is 300 °C; the rest are the same as in Example 1.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is only that: the calcination temperature is 600 °C; the rest are the same as in Example 1.

[0128] Comparative Example 4

[0129] The difference between this comparative example and Example 1 is only that: the calcination temperature is 1200 °C; the rest are the same as in Example 1.

[0130] Example

[0131] 1. Test the XRD patterns of the high-activity ultrafine calcium silicate monocarbon solidified cementitious materials of Examples 1-16 and the clinkers of Comparative Examples 1-4:

[0132] Test method: Grind the high-activity ultrafine calcium silicate monocarbon solidified cementitious material and pass it through a 200-mesh sieve, and conduct XRD test analysis using a high-resolution powdered X-ray diffractometer (XRD, Cu target). The test is scanned at a speed of 10 ° / min under 45 KV and 200 mA, and the scanning range is 10-70 °. ZnO is used as an internal standard with a dosage of 10%, and the Rietveld whole-spectrum fitting method is used for quantitative analysis.

[0133] Compare and analyze the test results of Examples 1-4 and Comparative Examples 1-4 (XRD patterns are as Figure 2-4 shown), as shown in Table 2 below:

[0134] Table 2

[0135]

[0136] Note: The grain size in the above table was obtained by quantitative analysis of XRD and calculated using the Scherrer formula.

[0137] As can be seen from Table 2 above, for Examples 1-4, the main crystal phase in the products calcined at 800-1100 °C is β-CS, and the grain size is relatively small (the grain size of the low-temperature type calcium silicate hydrate calcined at 1000-1100 °C using the prior art is generally above 75 nm). The calcination temperatures of Comparative Examples 2-3 are too low, and their main crystal phase is C-S-H, and the low-temperature type calcium silicate hydrate cannot be prepared; the calcination temperature of Comparative Example 4 is 1200 °C, and the main crystal phase of the product obtained by calcination is α-CS, and the grain size is significantly larger than that of the products obtained by calcining Examples 1-4 at 800-1100 °C.

[0138] Comparative analysis was performed on the test results of Examples 1-16 and Comparative Example 4, as shown in Table 3 below:

[0139] Table 3 Mineral composition

[0140]

[0141] As can be seen from Table 3:

[0142] For Examples 1-4 and Comparative Example 4, with the calcium-silicon ratio and water-solid ratio in step (1) fixed, as the calcination temperature continuously increases, the mineral composition of the highly active ultra-fine calcium silicate hydrate carbon solidification cementitious material changes significantly. The content of the low-temperature type calcium silicate hydrate in the mineral composition of the clinker increases with the increase of temperature, and the content of the amorphous phase gradually decreases. When the calcination temperature reaches 1200 °C (Comparative Example 4), due to reaching the phase transition temperature of calcium silicate hydrate, the low-temperature type calcium silicate hydrate becomes the high-temperature type calcium silicate hydrate.

[0143] When the calcium-silicon ratio is changed, as the calcium-silicon ratio increases, unreacted calcium oxide begins to appear in the mineral composition of the clinker, which is not conducive to safe production. When the calcium-silicon ratio of carbide slag and quartz powder increases (Examples 5-7 and Examples 11-12), when the calcination temperature continues to increase to 1100 °C, the content of dicalcium silicate in the clinker mineral phase will increase, the content of calcium silicate hydrate will decrease, and the content of calcium oxide will decrease (compared with the calcination temperature of 800 °C), but the relatively high calcination temperature still brings relatively high energy consumption.

[0144] At the same time, when the water-solid ratio of Example 8 is relatively low, dicalcium silicate will appear in the clinker mineral phase, which is caused by local agglomeration of the material; although too high a water-solid ratio (Example 9) has little effect on the mineral composition of the clinker, the energy consumption in the drying process will increase; when the water-solid ratio is low and the calcium-silicon ratio is increased (Examples 13-14), the content of dicalcium silicate will still increase, and the increase in the content of calcium oxide will cause an expansion problem (it will expand and break during the carbonization process).

[0145] In addition, the calcination time (Example 10) also has relatively little effect on the phase composition. Compared with the traditional solid-phase sintering method, this two-step synthesis method will first form a C-S-H precursor, and then remove the crystal water during the calcination process. Although the calcination time (Examples 10 and 15-16) has little effect on the clinker phase composition, too high a calcium-silica ratio (Examples 15-16) will lead to the formation of more calcium oxide, which is not conducive to safe production.

[0146] 2. Test the physical and mechanical properties of the carbonated products of the highly active ultrafine calcium silicate monocarbon solidified cementitious materials in Examples 1-16 and the carbonated products of the clinkers in Comparative Examples 1-4:

[0147] Preparation method of the carbonated product: Thoroughly mix the calcined clinker powder of the highly active ultrafine calcium silicate monocarbon solidified cementitious material with 10% water for 10 min, then place the mixture in a mold of 20 mm × 20 mm × 40 mm, and keep the pressure for 1 min under the condition of a forming pressure of 4 MPa. Press the mixture into a test block of 20 mm × 20 mm × 20 mm, put it into a reaction kettle, exhaust the air in the reaction kettle, close the exhaust valve, and introduce CO2 (purity 99.9%) into the reaction kettle, pressurize to 0.1 MPa, and carbonize for different times to obtain the carbonated product.

[0148] (1) The physical pictures of the carbonated products (carbonation time is 24 h) prepared by Examples 1-4 and Comparative Examples 1-4 according to the above method are as Figure 1 shown; from Figure 1 it can be seen that when the clinkers prepared at a calcination temperature below 800 °C in Comparative Examples 1-3 were carbonated, shrinkage and cracking occurred. This is because when the calcination temperature is too low, calcium silicate monocarbon cannot be formed; the reaction between the calcium source and the silicon source is insufficient, resulting in more calcium oxide in the material, which will also cause expansion and cracking during the carbonation process.

[0149] (2) Use a YAW-300 / 20 microcomputer-controlled pressure testing machine to test the compressive strength of the specimens, and measure the compressive strength after carbonation for 1 h, 4 h, and 24 h respectively. The pressurization rate is 0.3 mm / min. The average value of three specimens was calculated. The test results are shown in Table 4 below:

[0150] Collect and grind the test blocks after testing the compressive strength of carbonation for 24 h, weigh about 10 mg of the powder sample after carbonation for 24 h, and use a STA8122 / H (Shimadzu, Japan) thermal analyzer to test the carbonated sample under N2 atmosphere, with a heating rate of 10 °C / min and a test range of 25-1000 °C. Calculate the carbon fixation amount by calculating the mass loss within 500-850 °C. The test results are shown in Table 4 below:

[0151] Table 4

[0152]

[0153] In Table 4 above, the compressive strengths of Examples 5, 7, and 13 - 16 are 0 because the calcium oxide content in the carbon - cured cementitious material is too high, resulting in cracking of the specimens. During carbonization, first, a relatively dense matrix needs to be pressed under a certain pressure, and then carbon dioxide is introduced to carry out the carbonization reaction from the outside to the inside of the specimen. After pressing, the specimen is not completely dense, but there are still certain pores between the particles. The strength is obtained by the calcium carbonate and silica gel generated through the reaction binding to each other to form a dense hardened body. This process is a process of slight volume expansion. However, when calcium oxide undergoes the carbonization reaction, its volume expansion is relatively large, thus leading to the expansion and cracking of the specimen.

[0154] In summary, within the scope defined by the invention, the high - activity ultrafine calcium silicate monohydrate carbon - cured cementitious material has relatively high strength after carbonization curing and can be used in the fields of building materials such as outdoor building products and precast components. In addition, it can utilize industrial solid waste carbide slag on a large scale, which helps to reduce environmental pollution, improve resource utilization rate, and lower the use cost.

[0155] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a highly active ultrafine calcium monosilicate carbon-cured cementitious material, characterized in that, It includes the following steps: (1) Mix carbide slag, quartz powder and water evenly to obtain a mixed slurry; (2) Dry the mixed slurry to constant weight to obtain a dry material; (3) Calcinate the dry material to obtain a calcined product; the calcination temperature is 800 - 1100 °C; (4) Grind the calcined product to obtain the high - activity ultrafine calcium monosilicate carbon - solidified cementitious material.

2. The preparation method of the highly active ultrafine calcium monosilicate carbon solidified cementitious material according to claim 1, characterized in that, In step (1), the calcium - silicon ratio of the carbide slag to the quartz powder is (1 - 2):

1.

3. The preparation method of the highly active ultrafine calcium silicate monocarbon solidified cementitious material according to claim 1, characterized in that, In step (1), the water - solid ratio is (5 - 10):

1.

4. The preparation method of the highly active ultrafine calcium monosilicate carbon-cured cementitious material according to claim 1, wherein, In step (3), the calcination time is 1 - 2 h.

5. The preparation method of the highly active ultrafine calcium monosilicate carbon-cured cementitious material according to claim 1, characterized in that, In step (4), the particle size of the obtained high - activity ultrafine calcium monosilicate carbon - solidified cementitious material by grinding is ≤50 μm.

6. A highly active ultrafine calcium monosilicate carbon-cured cementitious material, characterized in that, The high - activity ultrafine calcium monosilicate carbon - solidified cementitious material is prepared by the method described in any one of claims 1 - 5.

7. The highly active ultrafine calcium monosilicate carbon-cured cementitious material according to claim 6, wherein The mineral composition of the high - activity ultrafine calcium monosilicate carbon - solidified cementitious material includes low - temperature calcium monosilicate, and the grain size of the low - temperature calcium monosilicate is <70 nm.

8. A method for preparing a carbonized product, characterized in that, It includes the following steps: I. Mix the high - activity ultrafine calcium monosilicate carbon - solidified cementitious material described in claim 6 or 7 with water evenly, then place it in a mold and form it to obtain a test block; II. Place the test block in a reaction kettle, introduce a gas containing CO2, and carry out pressure carbonization to obtain the carbonized product.

9. The method for preparing a carbonized product according to claim 8, characterized in that, In step I, the amount of water used is 5wt% - 10wt% of the high - activity ultrafine calcium monosilicate carbon - solidified cementitious material; the forming pressure is 4 - 6 MPa, and the pressure is maintained for 1 min under the forming pressure to obtain the test block; In step II, the pressure during pressure carbonization is 0.1 - 0.2 MPa.

10. A carbonized product, characterized in that, The carbonized product is prepared by the method described in claim 8 or 9.

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