Early-strength and slow-setting gelatinous material, and preparation method and application thereof

Abstract

This invention provides an early-strength retarded cementitious material, its preparation method, and its application. The early-strength retarded cementitious material comprises the following raw materials: 10-30 parts by weight of aluminate cement, 60-90 parts by weight of high-calcium minerals, and 0.01-0.6 parts by weight of a retarder. The high-calcium minerals contain 2%-40% free calcium oxide, and the weight ratio of aluminate cement to the high-calcium minerals is 1:(2-6). The retarder is an organic acid containing carboxyl groups. The method of this invention includes: mixing aluminate cement, high-calcium minerals, and a retarder to obtain a solid masterbatch; mixing the solid masterbatch with water at a liquid-to-solid ratio of 0.15-0.6, and stirring evenly to prepare the early-strength retarded cementitious material. This invention shortens the setting time of the early-strength retarded cementitious material by controlling the ratio of high-calcium minerals, aluminate cement, and a retarder, giving it excellent 2-hour compressive strength and enhancing its early strength.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, specifically to an early-strength, retarded cementitious material, its preparation method, and its application. Background Technology

[0002] With the increase in coal mining volume and scope, goaf areas and underground cavities pose a significant threat to the safety of surface buildings, bridges, and roads. Currently, the measure adopted in my country is to grout and fill goaf areas and underground cavities. Grouting often uses silicate cement as a raw material, which is mixed with water to form cement slurry for filling and reinforcement. However, cement grouting is relatively expensive.

[0003] Currently, the main cementitious material used is ordinary Portland cement. However, due to its long setting time (usually 7-8 hours for initial setting) and low 1-day strength, the backfilling efficiency is low, failing to meet the requirements of coal mines for backfilling as soon as mining begins. To address the issues of long setting time and low early strength, existing technologies generally use fast-setting cement as the main cementitious material, such as rapid-hardening sulfoaluminate cement and aluminate cement. However, this brings problems such as relatively high cost and excessively short setting time. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, the present invention uses high-calcium minerals and aluminate cement as raw materials. By controlling the addition ratio of the two materials and the retarder, the setting time can be shortened and the early strength can be increased.

[0005] To achieve the objectives of this invention, the following technical solution is adopted:

[0006] The present invention provides, in a first aspect, an early-strength retarded cementitious material, wherein the early-strength retarded cementitious material comprises the following components in parts by weight:

[0007] 10-30 parts by weight of aluminate cement

[0008] 60-90 parts by weight of high-calcium minerals

[0009] Retarder 0.01-0.6 parts by weight

[0010] The high-calcium mineral contains 2% to 40% free calcium oxide, the aluminate cement is in a weight ratio of 1:(2 to 6) to the high-calcium mineral, and the retarder is an organic acid containing carboxyl groups.

[0011] As is well known to those skilled in the art, adding a retarder to cementitious materials can prolong the setting time, but it also greatly reduces the early strength. However, the present invention adds a retarder containing carboxylate groups to aluminate cement and high-calcium minerals, which shortens the setting time and further improves the early strength of the cementitious materials.

[0012] The high-calcium minerals selected in this invention refer to minerals with a high content of free calcium oxide. Although the calcium oxide content in pulverized coal boiler fly ash reaches 5% or even 10%, it cannot achieve the synergistic effect with aluminate cement. This is because the calcium oxide in pulverized coal boiler fly ash is mainly inert calcium oxide, while the calcium oxide in circulating fluidized bed fly ash mainly exists as free calcium oxide, which can achieve the aforementioned ternary synergistic effect with aluminate cement and carboxylate-containing retarder. In some preferred embodiments, the content of free calcium oxide in the high-calcium minerals (i.e., the percentage of free calcium oxide by mass to the total mass of the high-calcium minerals) is 5% to 20%, for example, 8%, 10%, 15%, and 18%. The aluminate cement used in this invention can be commercially available, for example, it can be purchased from CA50 aluminate cement produced by Jianai in Zhengzhou, Henan.

[0013] In some preferred embodiments, the early-strength retarded cementitious material comprises the following components in parts by weight:

[0014] 20-30 parts by weight of aluminate cement

[0015] 70-90 parts by weight of high-calcium minerals

[0016] Retarder 0.1 to 0.5 parts by weight.

[0017] In some preferred embodiments, the weight ratio of the aluminate cement to the high-calcium mineral in this invention is 3:(7-13.5), for example, 3:8, 3:9, 3:10, 3:12.

[0018] In some specific embodiments, the high-calcium minerals used in this invention are selected from one or more of tourmaline slag, fly ash, gypsum, or limestone; wherein, the fly ash is selected from circulating fluidized bed fly ash with a high free calcium oxide content.

[0019] In some specific embodiments of the present invention, the retarder is selected from one or more of tartaric acid, citric acid or salicylic acid.

[0020] In a second aspect, the present invention provides a method for preparing the above-mentioned early-strength retarded cementitious material, the method comprising:

[0021] A solid masterbatch is obtained by mixing aluminate cement, high-calcium minerals, and retarder.

[0022] The solid masterbatch is mixed with water, the liquid-to-solid ratio of water to solid masterbatch is 0.15 to 0.6, and stirred evenly to prepare an early-strength retarded cementitious material.

[0023] In a third aspect, the present invention provides an application of the above-mentioned early-strength retarded cementitious material or the early-strength retarded cementitious material prepared by the above-mentioned preparation method.

[0024] For example, early-strength, slow-setting cementitious materials are used as mine backfill materials, grouting reinforcement materials, or mine sealing materials.

[0025] In some specific embodiments, the early-strength retarded cementitious material provided by the present invention can be compounded by adding other admixtures such as water-reducing agents, cellulose ethers and corresponding aggregates such as gangue, sand, gasification slag, tailings slag, etc. to prepare materials that meet different application requirements.

[0026] As is well known to those skilled in the art, initial setting time refers to the time from when water is added to cement until it begins to lose its plasticity; final setting time refers to the time required from when water is added to cement until the cement paste completely loses its plasticity and begins to develop strength. In some specific embodiments, the initial setting time of the cementitious material provided by the present invention can be shortened to 10-60 minutes, and the final setting time is ≤120 minutes.

[0027] In some specific embodiments, the 2-hour compressive strength of the cementitious material provided by the present invention is ≥2MPa, and the 1-day compressive strength is ≥15MPa; in some preferred embodiments, the 2-hour compressive strength of the early-strength retarded cementitious material is ≥5MPa, and the 1-day compressive strength of the early-strength retarded cementitious material is ≥20MPa.

[0028] The above technical solution achieves the following technical effects:

[0029] This invention shortens the setting time of early-strength retarded cementitious materials by controlling the weight ratio of high-calcium minerals containing free calcium oxide to aluminate cement to 1:(2-6), thereby giving them excellent 2-hour compressive strength. Furthermore, the early strength of the cementitious materials is enhanced through the synergistic effect of compounded admixtures containing carboxyl groups. Detailed Implementation

[0030] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0031] The sources of raw materials used in the following embodiments and comparative examples of this invention are as follows:

[0032] Aluminate cement: Aluminate cement with the grade CA50;

[0033] High-calcium minerals: high-calcium fly ash, in which the free calcium oxide content is as high as 5-40%;

[0034] Retarder: Tartaric acid, L + model;

[0035] Boric acid, industrial grade.

[0036] The test methods used in the following embodiments and comparative examples of this invention are as follows:

[0037] (1) Initial setting time: Tested in accordance with GBT 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures";

[0038] (2) Final setting time: Tested in accordance with GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures";

[0039] (3) 2h compressive strength: tested according to GBT 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete";

[0040] (4) Detection method for free calcium oxide in high-calcium minerals: The test shall be carried out in accordance with GB / T 176-2017 "Chemical Analysis Methods for Cement".

[0041] Example 1

[0042] (1) Mix 30 parts by weight of aluminate cement, 70 parts by weight of high-calcium mineral (free calcium oxide content is 5%) and 0.3 parts by weight of tartaric acid to obtain a solid masterbatch;

[0043] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0044] Example 2

[0045] (1) Mix 20 parts by weight of aluminate cement, 80 parts by weight of high-calcium mineral (free calcium oxide content is 12%) and 0.4 parts by weight of tartaric acid to obtain a solid masterbatch;

[0046] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0047] Example 3

[0048] (1) Mix 25 parts by weight of aluminate cement, 75 parts by weight of high-calcium mineral (free calcium oxide content is 20%) and 0.5 parts by weight of tartaric acid to obtain a solid masterbatch;

[0049] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0050] Example 4

[0051] (1) Mix 15 parts by weight of aluminate cement, 85 parts by weight of high-calcium mineral (free calcium oxide content is 40%) and 0.2 parts by weight of tartaric acid to obtain a solid masterbatch;

[0052] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0053] Comparative Example 1

[0054] (1) Mix 20 parts by weight of aluminate cement and 80 parts by weight of high-calcium mineral (free calcium oxide content is 12%) to obtain a solid masterbatch;

[0055] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0056] Comparative Example 2

[0057] The difference between this comparative example and comparative example 1 is that 0.8 parts by weight of tartaric acid were added in step (1).

[0058] Comparative Example 3

[0059] (1) Mix 10 parts by weight of aluminate cement, 90 parts by weight of high-calcium mineral (free calcium oxide content is 12%) and 0.2 parts by weight of retarder to obtain solid masterbatch;

[0060] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0061] Comparative Example 4

[0062] (1) Mix 30 parts by weight of aluminate cement, 70 parts by weight of high-calcium mineral (free calcium oxide content is 0.15%) and 0.3 parts by weight of tartaric acid to obtain a solid masterbatch;

[0063] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0064] Comparative Example 5

[0065] (1) Mix 20 parts by weight of aluminate cement, 80 parts by weight of high-calcium mineral (free calcium oxide content is 12%) and 0.3 parts by weight of boric acid to obtain a solid masterbatch;

[0066] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0067] Comparative Example 6

[0068] (1) Mix 50 parts by weight of aluminate cement, 50 parts by weight of high-calcium mineral (free calcium oxide content is 12%) and 0.4 parts by weight of tartaric acid to obtain a solid masterbatch;

[0069] (2) Mix the solid masterbatch with water at a liquid-solid ratio of 0.43 and stir evenly to make an early-strength retarded cementitious material.

[0070] The performance test results of the above-mentioned early-strength retarded cementitious materials are shown in Table 1 below:

[0071] Table 1

[0072]

[0073]

[0074] As can be seen from the data in the table above, by controlling the ratio of high-calcium minerals containing free calcium oxide to aluminate cement, the initial setting time of the cementitious material is shortened to 20-60 minutes, and the 2-hour compressive strength of the cementitious material is ≥2MPa, and the 1-day compressive strength is ≥15MPa.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An early-strength, retarded cementitious material, characterized in that, The early-strength retarded cementitious material comprises the following components in parts by weight: 10-30 parts by weight of aluminate cement 60-90 parts by weight of high-calcium minerals Retarder 0.1-0.6 parts by weight The high-calcium mineral contains 5% to 40% free calcium oxide, the aluminate cement is in a weight ratio of 1:(2 to 6) to the high-calcium mineral, and the retarder is an organic acid containing carboxyl groups.

2. The early-strength retarded cementitious material according to claim 1, characterized in that, The early-strength retarded cementitious material comprises the following components in parts by weight: 20-30 parts by weight of aluminate cement 70-90 parts by weight of high-calcium minerals Retarder 0.1 to 0.5 parts by weight.

3. The early-strength retarded cementitious material according to claim 1, characterized in that, The weight ratio of the aluminate cement to the high-calcium mineral is 3:(7-13.5).

4. The early-strength retarded cementitious material according to claim 3, characterized in that, The free calcium oxide content in the high-calcium mineral is 5% to 20%.

5. The early-strength retarded cementitious material according to any one of claims 1 to 4, characterized in that, The high-calcium mineral is selected from fly ash; wherein the fly ash is selected from circulating fluidized bed fly ash.

6. The early-strength retarded cementitious material according to claim 5, characterized in that, The retarder is selected from one or more of tartaric acid, citric acid, or salicylic acid.

7. A method for preparing an early-strength retarded cementitious material according to any one of claims 1 to 6, characterized in that, The preparation method includes: A solid masterbatch is obtained by mixing aluminate cement, high-calcium minerals, and retarder. The solid masterbatch is mixed with water, the liquid-to-solid ratio of water to solid masterbatch is 0.15 to 0.6, and stirred evenly to prepare an early-strength retarded cementitious material.

8. The application of an early-strength retarded cementitious material according to any one of claims 1 to 6, or an early-strength retarded cementitious material prepared by the preparation method described in claim 7. Its features are, The early-strength, slow-setting cementitious material is used as a mine backfill material, grouting reinforcement material, or mine sealing material.

9. The application according to claim 8, characterized in that, The initial setting time of the early-strength retarded cementitious material is 10-60 min, and the final setting time is ≤120 min.

10. The application according to claim 8 or 9, characterized in that, The 2-hour compressive strength of the early-strength retarded cementitious material is ≥2MPa, and the 1-day compressive strength of the early-strength retarded cementitious material is ≥15MPa.

11. The application according to claim 10, characterized in that, The 2-hour compressive strength of the early-strength retarded cementitious material is ≥5MPa, and the 1-day compressive strength of the early-strength retarded cementitious material is ≥20MPa.

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