Low-heat high-resistance hydraulic cementing material and preparation method thereof

Abstract

The invention discloses a low-heat high-resistance hydraulic cementing material and a preparation method thereof. Comprising the following raw materials in parts by weight: 20-60 parts of Portland cement clinker, 5-8 parts of natural gypsum, 2-3 parts of industrial byproduct gypsum, 25-50 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of a pozzolanic mixed material, 5-8 parts of limestone and sandstone, 15-35 parts of activated coal gangue and 0.2-0.4 part of a cement grinding aid. The method for activating the coal gangue comprises the following steps: grinding the coal gangue until the 80-micron sieve residue fineness reaches 15%, carrying out suspension decarburization thermal activation at the activation temperature of 920 DEG C, and rapidly cooling the activated coal gangue powder to 45 DEG C; all the raw materials are superfine powder and have the same specific surface area. The material is low in total amount of hydration heat, low in early strength and obviously increased in later strength, has the technical advantages of high pressure resistance, crack resistance, impact resistance and wear resistance, and has good properties such as ecological property and environmental adaptability.

Description

Technical Field

[0001] The present invention belongs to the technical fields of dams, marine engineering, underground or underwater engineering, etc., and specifically relates to a low-heat and high-resistant hydraulic cementitious material, a preparation method thereof, and an application thereof. Background Art

[0002] When traditional cement cannot meet some specific construction projects, special cement needs to be used. Special cement refers to building materials that can be used in certain specific projects, and it plays a very important role in major project fields such as water conservancy dams, nuclear power projects, and oil well projects in our country. For example, a nuclear power plant is built with cement concrete, so the concrete must have characteristics such as high strength, high crack resistance, and high durability; for water conservancy dams, oil well projects, etc., low-heat and high-resistant cement is needed to solve problems such as temperature cracks in dams and oil well collapses. Therefore, these cements play an indispensable role in specific fields.

[0003] "No dam is without cracks" has always been a major problem in the field of water conservancy projects. The problem of dam cracks has been affecting the quality and service life of project construction, and at the same time affecting the property safety in the reservoir area of the dam. Each additional crack means an additional potential danger. The reason for the generation of dam cracks is that cement is a brittle material. During the hydration and hardening process of cement, a large amount of heat is released, the internal temperature rises, forming an internal and external temperature difference, and the thermal expansion and contraction cause cracks in the concrete, especially for mass concrete, where the internal temperature is higher. Summary of the Invention

[0004] The purpose of the present invention is to break through the characteristics of traditional cement with high hydration heat and easy cracking, and provide a low-heat and high-resistant hydraulic cementitious material and a preparation method thereof, so that the material has a low total hydration heat, low early strength, obvious late strength growth, and technical advantages of high compressive strength, crack resistance, impact and abrasion resistance, and also has good properties such as ecologicality and environmental adaptability.

[0005] A low-heat and high-resistant hydraulic cementitious material, comprising the following raw materials in parts by weight: 20-60 parts of Portland cement clinker, 5-8 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 25-50 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of pozzolanic admixture, 5-8 parts of limestone and sandstone, 15-35 parts of activated coal gangue, 0.2-0.4 part of cement grinding aid; Method for activating coal gangue: Grinding the coal gangue until the residue on 80μm sieve reaches 15%, performing suspension decarbonization thermal activation, with the activation temperature being 920°C, and rapidly cooling the activated coal gangue powder to 45°C. Each raw material is an ultra-fine powder and has the same specific surface area. The specific surface area of the ultra-fine powder is controlled by ball mill grinding. The same specific surface area is more conducive to the uniformity of the later hydration reaction; conducive to the control of hydration heat, with a stable heat release rate; the temperature gradient is reduced, the uniform heat release reduces the temperature difference between the inside and the surface, and reduces the temperature stress; the strength development is stable: the uniform hydration reaction makes the concrete strength development more stable and improves the long-term strength;

[0006] Enhanced durability: The uniform microstructure reduces defects and improves impermeability and durability.

[0007] Furthermore, the loss on ignition of the activated coal gangue is not more than 1.5%, and the alumina is greater than 25%.

[0008] Further optimized scheme, (ordinary Portland cement corresponding to strength grade 32.5, with an actual strength greater than that of ordinary Portland cement of 32.5), comprising the following raw materials in parts by weight: 20-40 parts of Portland cement clinker, 5-7 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 25-40 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of pozzolanic admixture, 5-8 parts of limestone and sandstone, 15-20 parts of activated coal gangue, 0.2-0.4 part of cement grinding aid.

[0009] Further optimization, (ordinary Portland cement corresponding to strength grade 42.5, with an actual strength greater than that of ordinary Portland cement of 42.5), comprising the following raw materials in parts by weight: 50-60 parts of Portland cement clinker, 7-8 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 35-50 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of pozzolanic admixture, 5-8 parts of limestone and sandstone, 20-35 parts of activated coal gangue, 0.2-0.4 part of cement grinding aid.

[0010] Among them, the Portland cement clinker is an ordinary Portland cement clinker mainly composed of calcium silicate.

[0011] Among them, the natural gypsum conforms to G-class gypsum or M-class mixed gypsum specified in GB / T 5483-2024, with a grade of ≥55%; the industrial by-product gypsum is fluorogypsum, and the industrial by-product gypsum conforms to the provisions of GB / T 21371-2019.

[0012] The granulated blast furnace slag or slag powder conforms to the provisions of GB / T 203-2008; the fly ash conforms to the provisions of GB / T 1596-2017, except for the strength activity index and alkali content; the ammonium ion content in the fly ash is not greater than 210 mg / kg.

[0013] The pozzolanic admixture conforms to the technical requirements specified in GB / T 2847-2022, except for the 28-day compressive strength ratio of cement mortar; the methylene blue value of the limestone and sandstone is not greater than 1.4 g / kg, and the methylene blue value is tested according to the provisions in Appendix A of GB / T 35164-2017; the cement grinding aid conforms to the technical requirements specified in GB / T 26748-2011, and its addition amount does not exceed 0.5% of the mass of the high-performance special cementitious material.

[0014] For further optimization, the specific surface areas of the Portland cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, pozzolanic admixture, limestone and sandstone, coal gangue and grinding aid are all 550 cm 2 / kg.

[0015] The preparation method of the low-heat and high-resistant hydraulic cementitious material includes the following steps:

[0016] S1. Weigh according to the ratio, and perform ultrafine grinding on the Portland cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, pozzolanic admixture, limestone and sandstone, and activated coal gangue to obtain ultrafine powder materials;

[0017] S2. Place the grinding aid in a grinder and grind and mix it evenly to obtain auxiliary material powder;

[0018] S3. Place the ultrafine powder in S1 and the auxiliary material powder in S2 in a mixer. After the materials are fully homogenized, the low-heat and high-resistant hydraulic cementitious material is obtained.

[0019] Compared with the prior art, the features and beneficial effects of the present invention are:

[0020] (1) The present invention uses Portland cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, pozzolanic admixture, limestone and sandstone, activated coal gangue and cement grinding aid as raw materials to prepare a low-heat and high-resistant hydraulic cementitious material, aiming to improve the crack problem of dam concrete caused by temperature stress during the construction process, enhance the strength, crack resistance and durability of concrete, break the curse of "no dam without cracks", improve the safety and durability of the project, and ensure the long-term stable operation of the dam.

[0021] (2) The difference between low-heat cement and traditional medium-heat and ordinary cement lies in that the content of dicalcium silicate (C2S) is much higher than that of tricalcium silicate (C3S). The hydration characteristics significantly affect the hydration behavior of cement. Therefore, the early strength development of low-heat cement is slower than that of ordinary cement, but the later strength is higher. At the same time, the content of C3A is lower and the amount of Ca(OH)2 generated is less, so low-heat cement has better resistance to chloride ion and sulfate erosion. And the hydration heat of the present invention is lower and the strength is higher than that of general low-heat cement.

[0022] (3) By using the coal gangue suspension decarbonization self-balanced thermal activation technology, after the coal gangue is thermally activated, the material activity is effectively improved. It can not only be used as a high-quality cement admixture and concrete mineral admixture, but also as a low-carbon cementitious material. It has excellent properties such as controllable setting time, variable dosage, adjustable strength, and low heat. At the same time, it has properties such as rapid hardening, high strength, light weight, and density, and good compatibility with sand and gravel aggregates. During the activation process of coal gangue, most of the CaO in the coal gangue is removed at high temperature, resulting in a significant increase in the content of Al2O3. When the cementitious material undergoes a hydration reaction, a large amount of hydration heat will be generated when reacting with CaO. The activated coal gangue has a significantly reduced hydration heat due to the removal of most of the CaO at high temperature. At the same time, the significant increase in Al2O3 can accelerate the hydration reaction of cement, and the C3A generated by the hydration reaction enables the cement-based material to rapidly generate strength, which helps to improve the early strength of cement. Description of the Drawings

[0023] Figure 1 、 2 It is a picture of the strength performance test for Example 1;

[0024] Figure 3 It is a picture of the strength performance test for Example 3;

[0025] Figure 4 、 5 、6 is a picture of the strength performance test for Example 5;

[0026] Figure 7 、 8 It is a picture of the strength performance test for Example 7;

[0027] Figure 9 It is a picture of the strength performance test for Example 2;

[0028] Figure 10 It is a picture of the strength performance test for Example 4;

[0029] Figure 11 It is a picture of the strength performance test for Example 6;

[0030] Figure 12 It is a picture of the strength performance test for Example 8;

[0031] Figure 13 and Figure 14 They are pictures of the on-site compressive and flexural strength tests for Example 3;

[0032] Figure 15 and Figure 16 They are pictures of the on-site compressive and flexural strength tests for Example 4. Detailed implementation manners

[0033] To make the technical means, innovative features, achieved purposes and effects of the present invention easy to understand, the present invention is further described below.

[0034] The embodiments described herein are specific specific implementation manners of the present invention and are used to illustrate the concept of the present invention. They are all explanatory and exemplary and should not be construed as a limitation on the implementation manners of the present invention and the scope of the present invention. Except for the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0035] The technical solutions of the present invention will be further specifically described below in conjunction with specific embodiments.

[0036] Example 1

[0037] A low-heat and high-strength hydraulic cementitious material (ordinary Portland cement corresponding to a strength grade of 32.5) comprises the following raw materials in parts by weight: 35 parts of ordinary Portland cement clinker, 7 parts of natural gypsum, 2 parts of industrial by-product gypsum, 35 parts of granulated blast furnace slag or slag powder, 5 parts of fly ash, 2 parts of pozzolanic admixture, 6 parts of limestone and sandstone, 20 parts of activated coal gangue, and 0.2 part of cement grinding aid. The method for activating coal gangue: Grind the coal gangue to a residue fineness of 15% on a 80μm sieve, perform suspension decarbonization thermal activation, with the activation temperature being 920°C, and quickly cool the activated coal gangue powder to 45°C.

[0038] In this example, the natural gypsum conforms to the G-class gypsum specified in GB / T 5483, and the same applies hereinafter.

[0039] Preparation method of low-heat and high-resistant hydraulic cementitious material:

[0040] S1. Weigh according to the ratio, and perform ultrafine grinding on Portland cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, pozzolanic admixture, limestone and sandstone, and activated coal gangue to obtain ultrafine powder materials. The fineness requirement is expressed by the residue on a 45μm square hole sieve and should not be less than 5%. In this example, the specific surface area is 550cm 2 / / kg. The same applies to the following examples.

[0041] S2. Place the grinding aid in the grinder and grind and mix evenly to obtain auxiliary material powder. The fineness requirement is expressed by the residue on a 45μm square hole sieve and should not be less than 5%. In this example, the specific surface area is 420cm2 / kg. The same applies to the following examples.

[0042] S3. Place the ultrafine powder in S1 and the auxiliary material powder in S2 in the mixer. After the materials are fully homogenized, the low-heat and high-resistant hydraulic cementitious material is obtained.

[0043] Conduct corresponding tests on the prepared low-heat and high-resistant hydraulic cementitious material according to various components. When each component is qualified, seal and package the low-heat and high-resistant hydraulic cementitious material to obtain a special hydraulic cementitious material. The preparation processes of the following examples are the same.

[0044] Example 2

[0045] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 42.5), comprising the following raw materials in parts by weight: 50 parts of Portland cement clinker, 7 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 5 parts of fly ash, 2 parts of pozzolanic admixture, 5 parts of limestone and sandstone, 20 parts of activated coal gangue, and 0.2 parts of cement grinding aid.

[0046] Example 3

[0047] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 32.5), comprising the following raw materials in parts by weight: 40 parts of ordinary Portland cement clinker, 6 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 3 parts of pozzolanic admixture, 7 parts of limestone and sandstone, 18 parts of activated coal gangue, and 0.3 parts of cement grinding aid.

[0048] Example 4

[0049] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 42.5), comprising the following raw materials in parts by weight: 60 parts of ordinary Portland cement clinker, 7 parts of natural gypsum, 3 parts of industrial by-product gypsum, 45 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 3 parts of pozzolanic admixture, 7 parts of limestone and sandstone, 25 parts of activated coal gangue, and 0.3 part of cement grinding aid.

[0050] Example 5

[0051] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 32.5), comprising the following raw materials in parts by weight: 40 parts of ordinary Portland cement clinker, 7 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 4 parts of pozzolanic admixture, 8 parts of limestone and sandstone, 20 parts of activated coal gangue, and 0.4 part of cement grinding aid.

[0052] Example 6

[0053] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 42.5), comprising the following raw materials in parts by weight: 50 parts of ordinary Portland cement clinker, 8 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 3 parts of pozzolanic admixture, 7 parts of limestone and sandstone, 25 parts of activated coal gangue, and 0.3 part of cement grinding aid.

[0054] Example 7

[0055] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 32.5), comprising the following raw materials in parts by weight: 38 parts of ordinary Portland cement clinker, 7 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 4 parts of pozzolanic admixture, 8 parts of limestone and sandstone, 20 parts of activated coal gangue, and 0.4 part of cement grinding aid.

[0056] Example 8

[0057] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 42.5), comprising the following raw materials in parts by weight: 60 parts of ordinary Portland cement clinker, 8 parts of natural gypsum, 3 parts of industrial by-product gypsum, 50 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 4 parts of pozzolanic admixture, 8 parts of limestone and sandstone, 35 parts of activated coal gangue, and 0.4 part of cement grinding aid.

[0058] Preparation and curing of specimens: Refer to the provisions of GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)"; leave it to set until final setting under the conditions of relative humidity of 50% - 60% and ambient temperature of 18°C - 22°C. After final setting, demold and cure in the natural environment, and then conduct flexural strength and compressive strength tests in accordance with the standard GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)".

[0059] Determine the water requirement for standard consistency and setting time in accordance with JGJ / T70-2009 "Standard Test Method for Basic Properties of Building Mortar".

[0060] In addition, the prepared specimens are subjected to 24-hour water immersion treatment to test their strength, heat of hydration, and bonding performance. The water-soaked specimens and the dried specimens are also tested simultaneously to evaluate the performance of the products in the wet and dry states at different dosages. Table 1 shows the performance test results of each example:

[0061] Table 1. Strength performance test results of each example (corresponding strength grade is 32.5)

[0062]

[0063] Analyze the test results. The flexural strength of Example 1 at 28 days is 2.5 MPa, and the compressive strength is 32.1 MPa; the flexural strength of Example 3 at 28 days is 5.5 MPa, and the compressive strength at 28 days is 36.5 MPa; the flexural strength of Example 5 at 28 days is 4.1 MPa, and the compressive strength is 32.7 MPa; the flexural strength of Example 4 at 28 days is 4.9 MPa, and the compressive strength is 32.4 MPa. It can be seen that compared with Examples 1, 5, and 7, the flexural and compressive strengths of Example 3 are significantly improved. Therefore, the optimal solution is Example 3.

[0064] Table 2. Strength performance test results of each example (corresponding strength grade is 42.5)

[0065]

[0066] Analyze the test results. The flexural strength of Example 2 at 28 days is 5.8 MPa, and the compressive strength is 42.4 MPa; the flexural strength of Example 4 at 28 days is 7.0 MPa, and the compressive strength at 28 days is 45.5 MPa; the flexural strength of Example 6 at 28 days is 6.8 MPa, and the compressive strength is 42.6 MPa; the flexural strength of Example 4 at 28 days is 5.9 MPa, and the compressive strength is 43.1 MPa. It can be seen that compared with Examples 2, 6, and 8, the flexural and compressive strengths of Example 4 are significantly improved. Therefore, the optimal solution is Example 4.

[0067] Table 3 Heat of hydration test results of each example

[0068]

[0069] Analyze the test results. The heat of hydration at 3 days of Example 3 (corresponding strength grade is 32.5) is 170 kJ / kg, and the heat of hydration at 3 days of Example 4 (corresponding strength grade is 42.5) is 200 kJ / kg; the heat of hydration at 7 days of Example 3 (corresponding strength grade is 32.5) is 200 kJ / kg, and the heat of hydration at 7 days of Example 4 (corresponding strength grade is 42.5) is 230 kJ / kg. It can be seen from this that the heat of hydration at different grades of Examples 3 and 4 is relatively low compared with other examples. Therefore, the optimal solutions are Examples 3 and 4.

[0070] Comparative Example 1

[0071] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 32.5) comprises the following raw materials in parts by weight: 40 parts of ordinary Portland cement clinker, 6 parts of natural gypsum, 3 parts of industrial by-product gypsum, 40 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 3 parts of pozzolanic admixture, 7 parts of limestone and sandstone, and 0.3 part of cement grinding aid.

[0072] A low-heat and high-resistant hydraulic cementitious material (ordinary Portland cement corresponding to strength grade 42.5) comprises the following raw materials in parts by weight: 60 parts of ordinary Portland cement clinker, 7 parts of natural gypsum, 3 parts of industrial by-product gypsum, 45 parts of granulated blast furnace slag or slag powder, 6 parts of fly ash, 3 parts of pozzolanic admixture, 7 parts of limestone and sandstone, and 0.3 part of cement grinding aid. Based on Examples 3 and 4, various property comparisons are made without adding activated coal gangue, and the comparison results are as follows:

[0073] Table 4. Strength performance test results (corresponding to strength grade 32.5)

[0074]

[0075] Table 5. Strength performance test results (corresponding to strength grade 42.5)

[0076]

[0077] Table 6 Heat of hydration test results of examples and comparative examples

[0078]

[0079] Comparing Comparative Example 1 with Example 3, when the activated gangue was not added, the compressive strength of the low-heat hydraulic special cementitious material with a strength grade of 32.5 at 28 days was 32.7 MPa, and the flexural strength was 3.8 MPa. Comparing Comparative Example 1 with Example 4, the compressive strength of the low-heat hydraulic special cementitious material with a strength grade of 42.5 at 28 days was 42.3 MPa, and the flexural strength was 4.6 MPa. When the activated gangue was added, whether the corresponding strength grade was 32.5 or 42.5, its mechanical properties were significantly improved. Especially, the early strength growth was obvious, and at the same time, the hydration heat was significantly reduced. This was because most of the CaO in the gangue was removed at high temperature during the activation of the gangue, resulting in a significant increase in the content of Al2O3. When the cementitious material undergoes a hydration reaction, a large amount of hydration heat is generated by reacting with CaO. The activated gangue has all the CaO removed at high temperature, resulting in a significant reduction in the hydration heat. At the same time, the significant increase in Al2O3 can accelerate the hydration reaction of the cement. The C3A generated by the hydration reaction enables the cement-based material to generate strength rapidly, which helps to improve the early strength of the cement.

[0080] Table 7 Test Results of the Bonding Properties of Each Sample with a Strength Grade of 32.5

[0081]

[0082]

[0083] Analyzing the test results, the bonding strength of Example 1 at 28 days was 1.874 MPa; the bonding strength of Example 3 at 28 days was 2.092 MPa; the bonding strength of Example 5 at 28 days was 2.035 MPa; the bonding strength of Example 7 at 28 days was 1.868 MPa. It can be seen that compared with Example 3, the bonding strengths of Examples 1, 5, and 7 were all lower. Therefore, the optimal solution was Example 3.

[0084] Table 8 Test Results of the Bonding Properties of Each Example with a Strength Grade of 42.5

[0085]

[0086]

[0087] Analyzing the test results, the bonding strength of Example 2 at 28 days was 1.854 MPa; the bonding strength of Example 4 at 28 days was 3.026 MPa; the bonding strength of Example 6 at 28 days was 1.884 MPa; the bonding strength of Example 8 at 28 days was 3.017 MPa. It can be seen that for Example 6, since the surface of the test plate was too smooth, this data was excluded when calculating the average value. Compared with Example 4, the bonding strengths of Examples 2, 6, and 8 were all lower. Therefore, the optimal solution was Example 4.

[0088] The above embodiments are only partial manifestations of the present invention and do not cover all of the present invention. Based on the above embodiments and the accompanying drawings, those skilled in the art can obtain more implementation manners without creative efforts. Therefore, these implementation manners obtained without creative efforts should all be included within the protection scope of the present invention.

Claims

1. A low-heat and high-resistance hydraulic cementitious material, characterized by: The invention comprises the following raw materials in parts by weight: 20-60 parts of silicate cement clinker, 5-8 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 25-50 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of volcanic ash mixed materials, 5-8 parts of limestone and sandstone, 15-35 parts of activated coal gangue, and 0.2-0.4 parts of cement grinding aid; the method for activating the coal gangue is as follows: the coal gangue powder is ground to a fineness of 15% on an 80 μm sieve residue, and suspended decarbonization thermal activation is performed at an activation temperature of 920° C. The activated coal gangue powder is rapidly cooled to 45° C.; All raw materials are ultrafine powders and have the same specific surface area.

2. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: After activation, the loss on ignition of coal gangue is no more than 1.5%, and the alumina content is greater than 25%.

3. The low-heat and high-resistance hydraulic cementitious material according to claim 1 is characterized in that: The invention comprises the following raw materials in parts by weight: 20-40 parts of silicate cement clinker, 5-7 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 25-40 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of volcanic ash mixed materials, 5-8 parts of limestone and sandstone, 15-20 parts of activated coal gangue and 0.2-0.4 parts of cement grinding aid.

4. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 50-60 parts of silicate cement clinker, 7-8 parts of natural gypsum, 2-3 parts of industrial by-product gypsum, 35-50 parts of granulated blast furnace slag or slag powder, 5-6 parts of fly ash, 2-4 parts of volcanic ash mixed materials, 5-8 parts of limestone and sandstone, 20-35 parts of activated coal gangue and 0.2-0.4 parts of cement grinding aid.

5. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The silicate cement clinker is ordinary silicate cement clinker mainly composed of calcium silicate.

6. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The natural gypsum complies with the Class G gypsum or Class M mixed gypsum specified in GB / T5483-2024, with a grade ≥55%; the industrial by-product gypsum is fluorinated gypsum, and the industrial by-product gypsum complies with the provisions of GB / T 21371-2019.

7. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The granulated blast furnace slag or slag powder complies with the provisions of GB / T 203-2008; the fly ash complies with the provisions of GB / T 1596-2017, except for the strength activity index and alkali content; the ammonium ion content in the fly ash is not more than 210 mg / kg.

8. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The pozzolanic mixed material meets the technical requirements specified in GB / T 2847-2022, except for the 28d compressive strength ratio of cement mortar; the methylene blue value of the limestone and sandstone is not more than 1.4g / kg, and the methylene blue value is tested in accordance with the provisions of Appendix A of GB / T 35164-2017; the cement grinding aid meets the technical requirements specified in GB / T 26748-2011.

9. The low-heat and high-resistance hydraulic cementitious material according to claim 1, characterized in that: The silicate cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, volcanic ash mixed material, limestone and sandstone, coal gangue, and grinding aid are ultrafine powders, and the specific surface area is 550cm 2 / kg.

10. A method for preparing a low-heat and high-resistance hydraulic cementitious material according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. According to the proportion, silicate cement clinker, natural gypsum, industrial by-product gypsum, granulated blast furnace slag or slag powder, fly ash, volcanic ash mixed material, limestone and sandstone, activated coal gangue are ultra-finely ground to obtain ultra-fine powder material; S2, grinding the grinding aid in a grinder and mixing it evenly to obtain auxiliary material powder; S3. Place the ultrafine powder in S1 and the auxiliary material powder in S2 in a mixer, and after the materials are fully homogenized, a low-heat and high-resistance hydraulic cementitious material is obtained.

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