A mineral powder-based low-carbon self-leveling mortar and a preparation method thereof

Abstract

The application belongs to the technical field of building materials, and particularly relates to a mineral powder-based low-carbon self-leveling mortar and a preparation method thereof. The mineral powder-based low-carbon self-leveling mortar comprises the following components in parts by mass: modified slag powder 45-55 parts, cement 16-24 parts, dried sand 15-24 parts, iron-doped silicon carbide aerogel 2-4 parts, redispersible emulsion powder 1-2 parts, methyl cellulose ether 0.1-0.3 parts, polycarboxylic acid water reducer 0.2-0.5 parts, defoaming agent 0.1-0.2 parts, retarder 0.2-0.3 parts, and early strength agent 0.1-0.4 parts. The application successfully constructs a self-leveling mortar system with low carbon emission, high solid waste utilization rate, and excellent construction performance and mechanical properties through the synergistic effect of 2-methylpentanediamine modified slag powder and iron-doped silicon carbide aerogel.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a mineral powder-based low-carbon self-leveling mortar and its preparation method. Background Technology

[0002] Cement-based self-leveling mortar, with its excellent self-leveling properties, high construction efficiency, good surface flatness, and stable strength after hardening, has been widely used in various building floor leveling projects, such as industrial plants, underground garages, commercial supermarkets, and residential underfloor heating leveling layers. Compared with traditional on-site mixed mortar, self-leveling mortar does not require repeated manual rubbing and pressing; it can form a smooth surface by its own gravity, significantly reducing labor costs and construction time. Therefore, it has been increasingly promoted and applied in modern building construction.

[0003] However, despite the numerous advantages mentioned above, existing cement-based self-leveling mortars still suffer from significant and widespread technical defects in practical applications. Most conventional cement-based self-leveling mortars on the market currently use a high proportion of ordinary Portland cement as the sole cementing material, which has three main drawbacks: First, the excessive cement content leads to substantial carbon dioxide emissions during production, resulting in high raw material costs and failing to meet the current requirements for green and low-carbon building materials. Second, the high hydration shrinkage rate of the single cement-based cementing system makes the mortar prone to cracking, hollowing, and sandblasting during and after hardening, severely impacting the service life and decorative effect of the flooring. Third, the existing system has extremely low capacity to handle large quantities of industrial solid waste (such as slag powder and desulfurized gypsum) generated by industries like metallurgy and thermal power, resulting in insufficient solid waste resource utilization, causing significant resource waste and exacerbating environmental pollution. These long-standing technical defects have hindered the further application of self-leveling mortars in high-quality flooring projects.

[0004] Therefore, there is an urgent need to develop a new type of self-leveling mortar that is low in carbon emissions, has a high solid waste utilization rate, excellent mechanical and wear-resistant properties, and maintains good fluidity. This mortar can significantly reduce cement consumption, effectively dispose of industrial solid waste, and ensure that the mortar's workability and mechanical properties meet engineering requirements. Summary of the Invention

[0005] The primary objective of this invention is to provide a mineral powder-based low-carbon self-leveling mortar, which has excellent workability, superior mechanical properties, and good wear resistance.

[0006] The second objective of this invention is to provide a simple method for preparing the above-mentioned mineral powder-based low-carbon self-leveling mortar.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A mineral powder-based low-carbon self-leveling mortar comprises the following components in parts by weight: 45-55 parts modified slag powder, 16-24 parts cement, 15-24 parts dried sand, 2-4 parts iron-doped silicon carbide aerogel, 1-2 parts redispersible latex powder, 0.1-0.3 parts methyl cellulose ether, 0.2-0.5 parts polycarboxylate superplasticizer, 0.1-0.2 parts defoamer, 0.2-0.3 parts retarder, and 0.1-0.4 parts early-strength agent; The preparation method of the modified slag powder includes the following steps: Slag powder, desulfurized gypsum, sodium carbonate and 2-methylpentanediamine were added to water, ball-milled and mixed, and then dried to obtain modified slag powder.

[0008] Furthermore, the ratio of the slag powder, desulfurized gypsum, sodium carbonate, 2-methylpentanediamine and water is 1 g: (0.2-0.3) g: (0.06-0.12) g: (0.005-0.01) mL: (0.3-0.4) mL.

[0009] Furthermore, the ball milling mixing time is 1-2 hours; the drying temperature is 60-80 ℃.

[0010] Furthermore, the preparation method of the iron-doped silicon carbide aerogel includes the following steps: Silicon powder, iron powder, and polytetrafluoroethylene powder were ball-milled and mixed in ethanol, dried, and then subjected to a combustion reaction under an argon atmosphere. After cooling, crushing, and grinding, iron-doped silicon carbide aerogel was obtained.

[0011] Furthermore, the ratio of silicon powder, iron powder, polytetrafluoroethylene and ethanol is 1 g : (0.07-0.1) g : (1.25-1.9) g : (2.5-3.5) mL.

[0012] Furthermore, the combustion reaction is initiated by continuously heating a tungsten filament until a combustion reaction is triggered.

[0013] Furthermore, the cement is composed of rapid-hardening sulfoaluminate cement and silicate cement in a mass ratio of 1:(2-3); the dried sand is composed of 40-70 mesh dried sand and 70-140 mesh dried sand in a mass ratio of 1:(0.8-1.2).

[0014] Furthermore, the retarder is citric acid; the early strength agent is hydrated calcium silicate; the slag powder is S95 grade slag powder; and the defoamer is polydimethylsiloxane defoamer.

[0015] The above-mentioned method for preparing mineral powder-based low-carbon self-leveling mortar includes the following steps: Mix all raw material components evenly, put them into a dry powder mixer, premix, and then stir to obtain self-leveling mortar.

[0016] Furthermore, the premixing speed is 50-60 r / min and the time is 2-5 min; the re-stirring speed is 230-260 r / min and the time is 10-15 min.

[0017] The beneficial technical effects of this invention are as follows: 1. This invention utilizes a composite activator of desulfurized gypsum, sodium carbonate, and 2-methylpentanediamine to modify slag powder, effectively improving the fluidity and early mechanical properties of mortar. This organic amine-inorganic alkali-sulfate composite activating system exhibits excellent synergistic effects: 2-methylpentanediamine increases the hydration rate and promotes the dissolution of active substances, thereby enhancing early strength. Simultaneously, it adsorbs onto the surface of slag particles, improving their dispersibility and fluidity, and reducing fluidity loss over time. Sodium carbonate continuously provides hydroxide ions, further disrupting the internal structure of the slag, releasing active substances, promoting the stability of the cementitious system, and enhancing the overall strength of the mortar. Sulfate ions in the desulfurized gypsum react with active ions in the slag to form ettringite, filling pores and compensating for shrinkage, further improving mortar strength. Furthermore, this composite activating system effectively realizes the resource utilization of industrial solid waste, offering advantages such as low-carbon emission reduction, cost savings, and significant environmental benefits.

[0018] 2. This invention adds iron-doped silicon carbide aerogel to self-leveling mortar, which significantly improves the mechanical properties and wear resistance of the hardened mortar. Silicon carbide itself has high hardness, which can effectively enhance the hardness and wear resistance of the mortar; at the same time, the porous structure of the aerogel can improve the thermal and sound insulation properties of the mortar and reduce its density, which is beneficial to building energy conservation. However, silicon carbide aerogel itself is relatively brittle. This invention improves the structural stability of the aerogel by adding iron powder during the preparation process, generating iron carbides in situ, and forming a silicon carbide-iron carbide composite skeleton, thereby further improving the mechanical properties of the hardened mortar. Attached Figure Description

[0019] Figure 1 A scanning electron microscope image of the modified slag powder prepared in Example 1 of this invention; Figure 2 The image shows a scanning electron microscope (SEM) image of the iron-doped silicon carbide aerogel prepared in Example 5 of this invention. Detailed Implementation

[0020] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0021] The retarder used in this invention is citric acid; the early strength agent is hydrated calcium silicate; the slag powder is S95 grade slag powder; and the defoamer is polydimethylsiloxane defoamer.

[0022] (a) Preparation example Preparation Example 1 Preparation Example 1 provides a modified slag powder, which is prepared by the following process: Following the ratio of S95 grade slag powder, desulfurized gypsum, sodium carbonate, 2-methylpentanediamine, and water of 1 g: 0.25 g: 0.09 g: 0.008 mL: 0.35 mL, the slag powder, desulfurized gypsum, sodium carbonate, and 2-methylpentanediamine were added to water and ball-milled for 1.5 h. The mixture was then dried at 70 ℃ to obtain modified slag powder. The scanning electron microscope image of this modified slag powder is shown below. Figure 1 As shown.

[0023] Preparation Example 2 Preparation Example 2 provides a modified slag powder, which is prepared by the following process: According to the ratio of S95 grade slag powder, desulfurized gypsum, sodium carbonate, 2-methylpentanediamine and water, 1 g: 0.2 g: 0.06 g: 0.005 mL: 0.3 mL, slag powder, desulfurized gypsum, sodium carbonate and 2-methylpentanediamine were added to water, ball-milled in a ball mill for 1 h, and then dried at 60 ℃ to obtain modified slag powder.

[0024] Preparation Example 3 Preparation Example 3 provides a modified slag powder, which is prepared by the following process: According to the ratio of S95 grade slag powder, desulfurized gypsum, sodium carbonate, 2-methylpentanediamine and water, slag powder, desulfurized gypsum, sodium carbonate and 2-methylpentanediamine were added to water, and ball milled in a ball mill for 2 h. Then the mixture was dried at 80 ℃ to obtain modified slag powder.

[0025] Preparation Example 4 Preparation Example 4 provides a modified slag powder, which is prepared by the following process: According to the ratio of S95 grade slag powder, desulfurized gypsum, sodium carbonate, triethanolamine and water, 1 g: 0.25 g: 0.09 g: 0.008 mL: 0.35 mL, slag powder, desulfurized gypsum, sodium carbonate and triethanolamine are added to water, placed in a ball mill and ball-milled for 1.5 h, and then dried at 70 ℃ to obtain modified slag powder.

[0026] Preparation Example 5 Preparation Example 5 provides an iron-doped silicon carbide aerogel, which is prepared by the following process: Following a ratio of silicon powder, iron powder, polytetrafluoroethylene powder, and ethanol of 1 g: 0.08 g: 1.57 g: 3 mL, silicon powder, iron powder, and polytetrafluoroethylene powder were added to ethanol, ball-milled until homogeneous, and dried. The mixture was then placed in a reactor and heated with a tungsten filament under an argon atmosphere until a combustion reaction was initiated. After the reaction, the mixture was cooled, crushed, and ground to obtain iron-doped silicon carbide aerogel. A scanning electron microscope image of this iron-doped silicon carbide aerogel is shown below. Figure 2 As shown.

[0027] Preparation Example 6 Preparation Example 6 provides an iron-doped silicon carbide aerogel, prepared by the following process: According to the ratio of silicon powder, iron powder, polytetrafluoroethylene powder and ethanol, 1 g: 0.07 g: 1.25 g: 2.5 mL, silicon powder, iron powder and polytetrafluoroethylene powder are added to ethanol, ball-milled and mixed evenly and dried, and then placed in a reactor. Under an argon atmosphere, tungsten wire is continuously heated until a combustion reaction is initiated. After the reaction is completed, the mixture is cooled, crushed and ground to obtain iron-doped silicon carbide aerogel.

[0028] Preparation Example 7 Preparation Example 7 provides an iron-doped silicon carbide aerogel, prepared by the following process: According to the ratio of silicon powder, iron powder, polytetrafluoroethylene powder and ethanol, 1 g: 0.1 g: 1.9 g: 3.5 mL, silicon powder, iron powder and polytetrafluoroethylene powder are added to ethanol, ball-milled and mixed evenly and dried, and then placed in a reactor. Under an argon atmosphere, tungsten wire is continuously heated until a combustion reaction is initiated. After the reaction is completed, the mixture is cooled, crushed and ground to obtain iron-doped silicon carbide aerogel.

[0029] Preparation Example 8 Preparation Example 8 provides a silicon carbide aerogel, prepared by the following process: The silicon powder, polytetrafluoroethylene powder and ethanol were added to ethanol at a ratio of 1 g: 1.57 g: 3 mL, ball-milled and mixed evenly and dried. The mixture was then placed in a reactor and heated with a tungsten filament under an argon atmosphere until a combustion reaction was initiated. After the reaction was completed, the mixture was cooled, crushed and ground to obtain silicon carbide aerogel.

[0030] (II) Implementation Examples Example 1 Example 1 provides a mineral powder-based low-carbon self-leveling mortar, comprising the following components in parts by weight: 50 parts of modified slag powder from Preparation Example 1, 20 parts of cement, 20 parts of dried sand, 3 parts of iron-doped silicon carbide aerogel from Preparation Example 5, 1.5 parts of redispersible latex powder, 0.2 parts of methyl cellulose ether, 0.3 parts of polycarboxylate superplasticizer, 0.2 parts of polydimethylsiloxane defoamer, 0.2 parts of citric acid, and 0.3 parts of hydrated calcium silicate; wherein the cement is composed of rapid-hardening sulfoaluminate cement and silicate cement in a mass ratio of 1:2.5; and the dried sand is composed of 40-70 mesh dried sand and 70-140 mesh dried sand in a mass ratio of 1:1.

[0031] This embodiment also provides a method for preparing the above-mentioned self-leveling mortar, the specific steps of which are as follows: Prepare the raw material components according to the above proportions, put them into a dry powder mixer, premix at 55 r / min speed for 3 min, and then stir at 250 r / min speed for 12 min to obtain mineral powder-based low-carbon self-leveling mortar.

[0032] Example 2 Example 2 provides a mineral powder-based low-carbon self-leveling mortar, comprising the following components in parts by weight: 45 parts of modified slag powder from Preparation Example 2, 16 parts of cement, 15 parts of dried sand, 2 parts of iron-doped silicon carbide aerogel from Preparation Example 6, 1 part of redispersible latex powder, 0.1 parts of methyl cellulose ether, 0.2 parts of polycarboxylate superplasticizer, 0.1 parts of polydimethylsiloxane defoamer, 0.2 parts of citric acid, and 0.1 parts of hydrated calcium silicate; wherein the cement is composed of rapid-hardening sulfoaluminate cement and silicate cement in a mass ratio of 1:2; and the dried sand is composed of 40-70 mesh dried sand and 70-140 mesh dried sand in a mass ratio of 1:0.8.

[0033] Prepare the raw material components according to the above proportions, put them into a dry powder mixer, premix at 50 r / min speed for 5 min, and then stir at 230 r / min speed for 10 min to obtain mineral powder-based low-carbon self-leveling mortar.

[0034] Example 3 Example 3 provides a mineral powder-based low-carbon self-leveling mortar, comprising the following components in parts by weight: 55 parts of modified slag powder from Preparation Example 3, 24 parts of cement, 24 parts of dried sand, 4 parts of iron-doped silicon carbide aerogel from Preparation Example 7, 2 parts of redispersible latex powder, 0.3 parts of methyl cellulose ether, 0.5 parts of polycarboxylate superplasticizer, 0.2 parts of polydimethylsiloxane defoamer, 0.3 parts of citric acid, and 0.4 parts of hydrated calcium silicate; wherein the cement is composed of rapid-hardening sulfoaluminate cement and silicate cement in a mass ratio of 1:3; and the dried sand is composed of 40-70 mesh dried sand and 70-140 mesh dried sand in a mass ratio of 1:1.2.

[0035] Prepare the raw material components according to the above proportions, put them into a dry powder mixer, premix at 60 r / min speed for 2 min, and then stir at 260 r / min speed for 15 min to obtain mineral powder-based low-carbon self-leveling mortar.

[0036] (III) Comparative Example Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that the modified slag powder in Example 1 is replaced with the modified slag powder in Preparation Example 4.

[0037] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the iron-doped silicon carbide aerogel in Example 1 is omitted.

[0038] Comparative Example 3 Comparative Example 3 is basically the same as Example 1, except that the iron-doped silicon carbide aerogel in Example 1 is replaced with the silicon carbide aerogel in Preparation Example 8.

[0039] (iv) Test Examples The above Examples 1-3 and Comparative Examples 1-3 were prepared by adding self-leveling mortar to water at a mass ratio of 100:23 and mixing the mortar evenly with a mixer to obtain a self-leveling slurry. A portion of the self-leveling slurry was taken and tested according to JC / T 985-2017 "Cement-based Self-leveling Mortar for Floors" to determine the initial flowability, 20-minute flowability, 1-day and 28-day compressive strength, and abrasion resistance of Examples 1-3 and Comparative Examples 1-3.

[0040] Table 1. Performance test results of self-leveling mortars prepared in each embodiment and comparative example. As shown in Table 1, the mineral powder-based low-carbon self-leveling mortars prepared in Examples 1-3 of this invention all exhibit excellent construction performance, excellent mechanical properties, and good wear resistance.

[0041] Compared to Example 1, in Comparative Example 1, replacing 2-methylpentanediamine with triethanolamine in the preparation process of modified slag powder significantly reduced the initial and 20-minute flowability, and also resulted in a marked decrease in 1-day and 28-day compressive strength, along with poorer abrasion resistance. This indicates that 2-methylpentanediamine plays an irreplaceable key role in the composite activation system of this invention. Specifically, 2-methylpentanediamine, as an organic amine activator, can effectively increase the dissolution rate of active components in slag and accelerate the early hydration process, thereby giving the mortar higher early strength. On the other hand, its adsorption on the surface of slag particles can improve particle dispersibility, reduce flowability loss over time, and ensure the self-leveling performance of the mortar during the construction window. While triethanolamine also has a certain activating effect, its dispersion retention ability and early strengthening effect are inferior to 2-methylpentanediamine, making it difficult to meet the dual requirements of self-leveling mortar for flow retention and early strength.

[0042] Comparative Example 2, which omitted iron-doped silicon carbide aerogel, showed a significant decrease in the 28-day compressive strength of the mortar, with particularly pronounced deterioration in wear resistance. This indicates that iron-doped silicon carbide aerogel is not only a key component for improving wear resistance but also makes a significant contribution to later-stage strength. Specifically, silicon carbide itself possesses high hardness and high wear resistance; its introduction can form a micron-scale hard skeleton in the hardened mortar, effectively resisting surface wear. Simultaneously, while the porous structure of the aerogel helps reduce mortar density, without reinforcement modification, it is inherently brittle and prone to breakage under stress. This invention, by doping with iron, generates iron carbides in situ during the combustion reaction, constructing a silicon carbide-iron carbide composite skeleton. This significantly improves the structural stability of the aerogel particles and their interfacial bonding with the cementitious matrix, thereby enhancing both wear resistance and the overall compressive strength of the mortar.

[0043] Comparative Example 3 replaced iron-doped silicon carbide aerogel with undoped ordinary silicon carbide aerogel. Although the wear resistance and strength improved compared to Comparative Example 2, they were still significantly inferior to Example 1. This indicates that while undoped silicon carbide aerogel possesses a certain degree of hardening reinforcement, its high brittleness and weak interfacial bonding with the matrix make it prone to microcracks during mixing, construction, and hardening, thus weakening the reinforcement effect. In contrast, the composite skeleton structure formed by iron doping in this invention not only improves the toughness of the aerogel itself but also optimizes its dispersion and anchoring effect in mortar, thereby achieving a simultaneous improvement in wear resistance and mechanical properties.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A mineral powder-based low-carbon self-leveling mortar, characterized in that, The composition includes the following components in parts by weight: 45-55 parts modified slag powder, 16-24 parts cement, 15-24 parts dried sand, 2-4 parts iron-doped silicon carbide aerogel, 1-2 parts redispersible latex powder, 0.1-0.3 parts methyl cellulose ether, 0.2-0.5 parts polycarboxylate superplasticizer, 0.1-0.2 parts defoamer, 0.2-0.3 parts retarder, and 0.1-0.4 parts early strength agent; The preparation method of the modified slag powder includes the following steps: Slag powder, desulfurized gypsum, sodium carbonate and 2-methylpentanediamine were added to water, ball-milled and mixed, and then dried to obtain modified slag powder.

2. The mineral powder-based low-carbon self-leveling mortar according to claim 1, characterized in that, The ratio of slag powder, desulfurized gypsum, sodium carbonate, 2-methylpentanediamine and water is 1 g: (0.2-0.3) g: (0.06-0.12) g: (0.005-0.01) mL: (0.3-0.4) mL.

3. The mineral powder-based low-carbon self-leveling mortar according to claim 1, characterized in that, The ball milling mixing time is 1-2 h; the drying temperature is 60-80 ℃.

4. The mineral powder-based low-carbon self-leveling mortar according to claim 1, characterized in that, The preparation method of the iron-doped silicon carbide aerogel includes the following steps: Silicon powder, iron powder, and polytetrafluoroethylene powder were ball-milled and mixed in ethanol, dried, and then subjected to a combustion reaction under an argon atmosphere. After cooling, crushing, and grinding, iron-doped silicon carbide aerogel was obtained.

5. The mineral powder-based low-carbon self-leveling mortar according to claim 4, characterized in that, The ratio of silicon powder, iron powder, polytetrafluoroethylene and ethanol is 1 g : (0.07-0.1) g : (1.25-1.9) g : (2.5-3.5) mL.

6. The mineral powder-based low-carbon self-leveling mortar according to claim 4, characterized in that, The combustion reaction is initiated by continuously heating a tungsten filament until a combustion reaction is triggered.

7. The mineral powder-based low-carbon self-leveling mortar according to claim 1, characterized in that, The cement is composed of rapid-hardening sulfoaluminate cement and silicate cement in a mass ratio of 1:(2-3); the dried sand is composed of 40-70 mesh dried sand and 70-140 mesh dried sand in a mass ratio of 1:(0.8-1.2).

8. The mineral powder-based low-carbon self-leveling mortar according to claim 1, characterized in that, The retarder is citric acid; the early strength agent is hydrated calcium silicate; the slag powder is S95 grade slag powder; and the defoamer is polydimethylsiloxane defoamer.

9. A method for preparing mineral powder-based low-carbon self-leveling mortar according to any one of claims 1-8, characterized in that, Includes the following steps: Mix all raw material components evenly, put them into a dry powder mixer, premix, and then stir to obtain self-leveling mortar.

10. The method for preparing mineral powder-based low-carbon self-leveling mortar according to claim 9, characterized in that, The premixing speed is 50-60 r / min and the time is 2-5 min; the re-stirring speed is 230-260 r / min and the time is 10-15 min.

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