Liquid cement grinding aid and preparation method thereof

Abstract

The invention discloses a liquid cement grinding aid and a preparation method thereof, and belongs to the technical field of cement grinding aid preparation, the liquid cement grinding aid comprises the following raw materials by weight: 76-80% of water, 18-20% of hydrochloric acid and 2-4% of sodium hexametaphosphate. The preparation method of the liquid cement grinding aid comprises the following steps: uniformly mixing the raw materials according to the weight percentage, and carrying out activation reaction to prepare the liquid cement grinding aid. The cement grinding aid disclosed by the invention is prepared by mixing hydrochloric acid, water and sodium hexametaphosphate according to a specific proportion, and through scientific regulation and control of the synergistic effect of all the components, the cement grinding aid has good grinding aiding performance and remarkably improves the specific surface area and grinding aiding efficiency of cement; the component design fully considers the cement hydration process and the compatibility with the water reducing agent.

Description

Technical Field

[0001] This invention belongs to the field of cement grinding aid preparation technology, and particularly relates to a liquid cement grinding aid and its preparation method. Background Technology

[0002] With the widespread application of liquid grinding aids in cement production, their significant improvement in cement grinding efficiency has been widely recognized. However, in recent years, the compatibility issues between cement with added grinding aids and concrete admixtures (especially water-reducing agents) have become increasingly prominent, gradually becoming a technical challenge of common concern to cement and concrete manufacturers. In practical applications, although many traditional grinding aids can effectively improve grinding efficiency and reduce energy consumption, their components may introduce excessive alkaline substances or organic impurities, leading to changes in the surface properties of cement particles, which in turn affects the rheological properties of cement paste, and in severe cases, may even cause a decline in concrete workability and affect construction quality.

[0003] Most liquid grinding aids currently on the market are mainly composed of organic compounds such as alkanolamines, polyols, or fatty acid salts. These components can affect the compatibility between cement and water-reducing agents to some extent, making it difficult to meet the requirements of modern high-performance concrete for high fluidity, low slump loss, and long-term plasticity retention. Therefore, developing a new type of environmentally friendly liquid grinding aid that can maintain excellent grinding effects while improving or at least not impairing the compatibility between cement and water-reducing agents has become an urgent technical need for many cement companies. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a liquid cement grinding aid and its preparation method. This grinding aid is formulated by mixing hydrochloric acid, water, and sodium hexametaphosphate in a specific ratio. Through scientific regulation of the synergistic effect of each component, it not only possesses excellent grinding aid performance, significantly improving the specific surface area and grinding efficiency of cement, but more importantly, its component design fully considers the cement hydration process and compatibility with water-reducing agents.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of this invention:

[0007] A liquid cement grinding aid, comprising the following raw materials by weight percentage:

[0008] Water 76-80%, hydrochloric acid 18-20%, and sodium hexametaphosphate 2-4%.

[0009] Optionally, the liquid cement grinding aid comprises, by weight percentage, the following raw materials:

[0010] Water 76%, hydrochloric acid 20%, and sodium hexametaphosphate 4%.

[0011] Optionally, the liquid cement grinding aid comprises, by weight percentage, the following raw materials:

[0012] Water 80%, hydrochloric acid 18%, and sodium hexametaphosphate 2%.

[0013] Optionally, the hydrochloric acid has a mass concentration of 36.5%.

[0014] A method for preparing a liquid cement grinding aid includes the following steps:

[0015] The raw materials are mixed evenly according to their weight percentages and activated to prepare the liquid cement grinding aid.

[0016] Optionally, the preparation method specifically includes the following steps:

[0017] Hydrochloric acid was added to water and stirred for 5 minutes. Then sodium hexametaphosphate was added to the resulting mixture and stirred for 5 minutes to carry out the activation reaction, thus preparing the liquid cement grinding aid.

[0018] Furthermore, the prepared liquid cement grinding aid contains 6.6-7.3% HCl in its total content.

[0019] Furthermore, the liquid cement grinding aid contains 6.6% or 7.3% HCl in its total content.

[0020] The above-mentioned liquid cement grinding aid is used to improve the mechanical properties of cement and the compatibility between cement and water-reducing agent.

[0021] Optionally, the liquid cement grinding aid is incorporated at an amount of 0.8 wt.% of the cement.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] 1. This invention involves adding 18-20% hydrochloric acid, 76-80% water, and 2-4% sodium hexametaphosphate in a specific order to a stirred reactor. The mixture is then stirred to activate the reaction, forming a novel liquid cement grinding aid that alleviates the fluidity or plasticity of cement paste, slows down the hydration rate during the early and induction stages of cement induction, and thus improves the compatibility of cement products with concrete water-reducing agents. The preparation method of this invention is simple, low-cost, and easy to implement.

[0024] 2. From the perspective of usage effects, the liquid cement grinding aid produced using hydrochloric acid, sodium hexametaphosphate, and water is a novel technological product with multiple functions, including grinding assistance, strengthening, water reduction, and good compatibility. When directly added at 0.8% of the total cement weight for cement production, it can significantly improve water reduction and compatibility, increase fluidity, improve yield and cement strength, increase specific surface area, reduce water demand, and lower production costs.

[0025] 3. Based on the actual test data of this invention, it can be seen that, compared with commercially available liquid grinding aids, the liquid cement grinding aid prepared using this invention can improve the grinding efficiency of cement production, increase cement hourly output by 75-77 tons, reduce cement consistency water requirement by 1.0-1.1%, improve cement compatibility by 135-139 mm, improve fluidity by 140-145 mm, and increase specific surface area by 96-107 m². 2 / kg, increasing the 3-day flexural strength of cement by 1.3-1.5 MPa, the 3-day compressive strength by 7.9-8.7 MPa, the 28-day flexural strength by 1.1-4 MPa, and the 28-day compressive strength by 8.8-10.9 MPa. In other words, the liquid cement grinding aid prepared by this invention can effectively improve the problem of poor compatibility between cement and water-reducing agents, truly achieving energy conservation and emission reduction, environmental protection, and improved economic benefits. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] This invention discloses a method for preparing a liquid cement grinding aid by mixing hydrochloric acid, water, and sodium hexametaphosphate, which is used to improve the compatibility of cement with water-reducing agents. Specifically:

[0032] A method for preparing a liquid cement grinding aid includes the following steps:

[0033] By weight percentage, it includes the following raw materials:

[0034] Hydrochloric acid 18-20%, sodium hexametaphosphate 2-4%, and water 76-80%;

[0035] Water was placed in a stirred reactor, and then hydrochloric acid (containing 36.5% HCl as the main component) was added to the stirred reactor and stirred for 5 minutes. Sodium hexametaphosphate was then added and stirred for another 5 minutes to carry out the activation reaction, thus preparing a liquid cement grinding aid.

[0036] The purpose of stirring is to enable the material and water molecules to undergo an effective activation reaction, forming a new liquid cement grinding aid that can alleviate the fluidity or plasticity of cement paste, as well as slow down the hydration rate in the early and induction stages of cement induction, thereby improving the compatibility of cement products with concrete water-reducing agents.

[0037] Mechanism analysis of the liquid cement grinding aid prepared by this invention:

[0038] This invention utilizes the organic combination of the effective components in hydrochloric acid with water molecules and the mineral composition of sodium hexametaphosphate to form a novel liquid cement grinding aid that can alleviate the fluidity or plasticity of cement paste, as well as slow down the hydration rate during the early and induction stages of cement induction, thereby improving the compatibility of cement products with concrete water-reducing agents. In other words, this grinding aid can slow down the hydration rate of cement paste during the early and induction stages of hydration induction, thus improving the compatibility of cement and concrete water-reducing agents and increasing the fluidity of the cement paste.

[0039] In contrast, most grinding aids currently on the market are compounded from alkanolamines, polyols, amines, lignin sulfonates, and a small amount of inorganic salts. While they can accelerate the early hydration of cement, excessively rapid early hydration can cause cement to quickly transform into hydration products, leading to premature loss of fluidity in the cement paste. Simultaneously, the large amount of hydration products generated can adsorb water-reducing agent molecules, reducing the effective concentration of water-reducing agents in the liquid phase, thus resulting in poorer flow properties and decreased compatibility of the cement paste.

[0040] The liquid cement grinding aid of this invention not only possesses excellent grinding aid effects but also significantly improves the compatibility between cement and water-reducing agents. Its mechanism of action lies in reducing the calcium ion concentration in cement, prolonging the cement hydration induction period, effectively inhibiting the initial hydration reaction of C3S, and alleviating the phenomenon of insoluble coatings forming on the surface of C3S in cement clinker, thereby slowing down the overall hydration reaction rate of cement. This not only reduces the water demand of the cement paste but also facilitates the adsorption of water-reducing agent molecules on the surface of cement particles, preventing the water-reducing effect from being weakened. Simultaneously, this grinding aid can also inhibit the crystal growth of hydration product CH, delaying the hydration rate of C3S and C3A, further optimizing the rheological properties of the cement paste. Therefore, the liquid cement grinding aid prepared by this invention not only improves the compatibility between cement and water-reducing agents but also significantly enhances fluidity while increasing the specific surface area and strength of cement, achieving a comprehensive performance improvement with a doubling of fluidity values.

[0041] All raw materials used in this invention were purchased from the market.

[0042] The technical solution of the present invention will be further illustrated by the following embodiments.

[0043] Example 1

[0044] A method for preparing a liquid cement grinding aid includes the following steps:

[0045] By weight percentage, it includes the following raw materials:

[0046] 20% hydrochloric acid, 4% sodium hexametaphosphate, and 76% water;

[0047] Water was placed in a stirred reactor, then hydrochloric acid (36.5% by mass) was added and stirred for 5 minutes. Sodium hexametaphosphate was then added and stirring continued for another 5 minutes to activate the reaction, thus preparing a liquid cement grinding aid. The purpose of stirring is to enable an effective activation reaction between the material and water molecules. The activated material forms a new liquid cement grinding aid that can alleviate the fluidity or plasticity of cement paste, as well as slow down the hydration rate in the early and induction stages of cement induction, thereby improving the compatibility of cement products with concrete water-reducing agents.

[0048] The cement grinding aid prepared in Example 1 was used at 0.8% of the total cement weight to replace commercially available liquid grinding aid (purchased from Shandong Zaozhuang Grinding Aid Co., Ltd.) in the production of cement products. These cement products comprised raw materials: cement, polycarboxylate superplasticizer, and grinding aid, wherein the grinding aid was 0.8 wt% of the cement weight and the polycarboxylate superplasticizer was 1.5 wt% of the cement weight; the same applies to Example 2. The physical properties of the prepared cement products are shown in Table 1 (the initial setting time of 2:05 in the table represents two hours and five minutes, and so on). The product quality technical indicators were tested according to GB / T26748-2011 "Cement Grinding Aid" standard and GB / 175-2007 General Cement Standard. This invention... The quality technical indicators for cement grinding aids are as follows: grinding effect P.1: >45.5%, standard consistency water requirement P.1 <24.0%, initial setting time P.1: >5min, final setting time P.1: >10min, boiling stability qualified, cement mortar fluidity P.1: >140mm, compatibility >135mm, cement mortar compressive strength 3-day P.1: >7.9MPa, 28-day P.1: >8.8MPa, mortar shrinkage rate 28-day P.1: <0.008%, chloride ion P.1: <0.01%, odor P.1: no irritating odor, solid content P.1: >53.6%, density P.1: >1.196%, pH value P.1: >8.8.

[0049] Table 1. Comparison of physical properties of cement prepared with liquid cement grinding aid, commercially available grinding aid, and cement prepared without grinding aid in Example 1.

[0050]

[0051] As shown in Table 1, the liquid cement grinding aid prepared in Example 1 of this invention, when used to replace commercially available grinding aids in cement production, solves the problem of poor compatibility between cement and water-reducing agents. Specifically, compared to commercially available grinding aids, the specific surface area of ​​cement products incorporating the liquid cement grinding aid of this invention increases by 96 m². 2 / kg, reduces consistency water requirement by 1.0%, improves compatibility by 135mm and fluidity by 140mm, slows down setting time by 5-10 minutes, increases cement flexural strength by 1.3MPa at 3 days and 1.0MPa at 28 days; increases compressive strength by 7.9MPa at 3 days and 10.9MPa at 28 days; and improves grinding efficiency by 45.5%.

[0052] Example 2

[0053] A method for preparing a liquid cement grinding aid includes the following steps:

[0054] By weight percentage, it includes the following raw materials:

[0055] 18% hydrochloric acid, 2% sodium hexametaphosphate, and 80% water;

[0056] Water was placed in a stirred reactor, then hydrochloric acid (containing 36.5% HCl as the main component) was added and stirred for 5 minutes. Sodium hexametaphosphate was then added and stirring continued for another 5 minutes to activate the reaction, thus preparing a liquid cement grinding aid. The purpose of stirring is to enable an effective activation reaction between the material and water molecules. The activated material forms a new liquid cement grinding aid that can alleviate the fluidity or plasticity of cement paste and slow down the hydration rate in the early and induction stages of cement induction, thereby improving the compatibility of cement products with concrete water-reducing agents.

[0057] The cement grinding aid prepared in Example 2 was used at 0.8% of the total cement weight to replace commercially available liquid grinding aid (purchased from Anhui Tianchang Grinding Aid Co., Ltd.) in the production of cement products. The physical properties of the resulting cement products are shown in Table 2. The product quality technical indicators were tested according to GB / T26748-2011 "Cement Grinding Aids" standard and GB / 175-2007 General Cement Standard. The quality technical indicators of the cement grinding aid of this invention were: grinding effect P.1: >45.5%, standard consistency water requirement P.1: <24.0%. The initial setting time (P.1) is >5 min, the final setting time (P.1) is >10 min, the boiling stability is qualified, the cement mortar fluidity (P.1) is >140 mm, the compatibility is >135 mm, the cement mortar compressive strength at 3 days (P.1) is >7.9 MPa, at 28 days (P.1) is >8.8 MPa, the mortar shrinkage rate at 28 days (P.1) is <0.006%, the chloride ion content (P.1) is <0.01%, the odor (P.1) is odorless, the solid content (P.1) is >53.3%, the density (P.1) is >1.195%, and the pH value (P.1) is >8.7.

[0058] Table 2 compares the physical properties of cement prepared with the liquid cement grinding aid, commercially available grinding aid, and cement prepared without grinding aid in Example 2.

[0059]

[0060] As shown in Table 2, the liquid cement grinding aid prepared in Example 2 exhibits excellent compatibility with cement and water-reducing agents, demonstrating significant water-reducing effects, substantial increases in compatibility and fluidity, stable performance, and a highly significant enhancement in grinding aid performance, far exceeding the effects of adding commercial grinding aids or not adding grinding aids. Specifically, compared to commercial grinding aids, the specific surface area of ​​cement products incorporating the liquid cement grinding aid of this invention increased by 107 m². 2 / kg, reducing consistency water requirement by 1.1%, improving compatibility by 139mm and fluidity by 145mm, easing setting time by 10-15 minutes, increasing cement 3-day flexural strength by 1.5MPa, 28-day flexural strength by 1.0MPa, 3-day compressive strength by 8.7MPa, and 28-day compressive strength by 8.8MPa, and also increasing mill hourly output by 45.8%.

[0061] In summary, the liquid cement grinding aid prepared using the method of this invention forms a new type of liquid cement grinding aid that alleviates the fluidity or plasticity of cement paste and slows down the hydration rate in the early and induction stages of cement induction, thereby improving the compatibility of cement products with concrete water-reducing agents. Furthermore, the preparation method of this invention is simple, low-cost, and easy to implement, truly achieving energy conservation and emission reduction, protecting the environment while improving economic benefits.

[0062] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A liquid cement grinding aid, characterized in that, By weight percentage, it includes the following raw materials: Water 76-80%, hydrochloric acid 18-20%, and sodium hexametaphosphate 2-4%.

2. The liquid cement grinding aid according to claim 1, characterized in that, Calculated as a percentage by weight It includes the following raw materials: 76% water, 20% hydrochloric acid, and 4% sodium hexametaphosphate.

3. The liquid cement grinding aid according to claim 1, characterized in that, The ingredients, by weight percentage, include: 80% water, 18% hydrochloric acid, and 2% sodium hexametaphosphate.

4. The liquid cement grinding aid according to claim 1, characterized in that, The hydrochloric acid has a mass concentration of 36.5%.

5. A method for preparing a liquid cement grinding aid, characterized in that, Includes the following steps: The raw materials are mixed evenly according to the weight percentage and activated to prepare the liquid cement grinding aid according to any one of claims 1-4.

6. The method for preparing a liquid cement grinding aid according to claim 5, characterized in that, Specifically, the following steps are included: Hydrochloric acid was added to water and stirred for 5 minutes. Sodium hexametaphosphate was then added to the resulting mixture and stirred for 5 minutes to activate the reaction, thus preparing the liquid cement grinding aid.

7. The method for preparing a liquid cement grinding aid according to claim 5, characterized in that, The liquid cement grinding aid contains 6.6-7.3% HCl by mass.

8. The method for preparing a liquid cement grinding aid according to claim 7, characterized in that, The liquid cement grinding aid contains 6.6% or 7.3% HCl by mass.

9. The application of the liquid cement grinding aid as described in any one of claims 1-4 in improving the mechanical properties of cement and the compatibility between cement and water-reducing agent.

10. The application of the liquid cement grinding aid according to claim 9 in improving the mechanical properties of cement and the compatibility between cement and water-reducing agent, characterized in that, The liquid cement grinding aid is added at a rate of 0.8 wt.% of the cement.

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