Alkali-free and chlorine-free powder soluble accelerator, method of making and method of use

Abstract

The application discloses a kind of alkali-free and chlorine-free powdery masterbatch soluble accelerator, preparation method and use method thereof, belong to building material admixture technical field.The application uses sulphate and fluorine aluminum compound as base material, specifically includes: base material 45-60wt.%., stabilizer 5-10wt.%., polycarboxylic acid 3-5wt.%., lignosulfonate 5-10wt.%., pH regulator 1-1.5wt.%., defoaming agent 5-8wt.%., calcium formate 10-12wt.%., and the rest is water.Preparation process is base material pretreatment, dissolving mixing, feeding, adjusting pH value, decoloring treatment, concentration drying.The accelerator prepared by the application has high efficient coagulation effect, good crack resistance, impermeability, environmental protection and high efficiency, and can be widely applied to various cement-based materials;powdery masterbatch dissolves in water to obtain liquid accelerator applied to tunnel injection construction, which provides strong guarantee for safety and stability of tunnel.

Description

Technical Field

[0001] This invention relates to the field of building material admixtures, and in particular to an alkali-free and chlorine-free powdered soluble quick-setting agent, its preparation method, and its application method. Background Technology

[0002] With the rapid development of the modern construction industry, concrete, as a primary building material, has seen its performance and construction efficiency become a focus of attention. This is especially true in specialized projects such as tunnels, slope protection, and mines, where extremely high demands are placed on the rapid setting and hardening performance of concrete. While traditional quick-setting agents can meet construction requirements to some extent, they often contain alkalinity and chloride ions, which can not only cause long-term stability issues in concrete structures but also potentially have adverse effects on the environment and construction workers.

[0003] Chinese patent CN103553406A discloses an alkali-free and chlorine-free liquid quick-setting agent based on industrial polyaluminum sulfate. However, this patent application for the alkali-free liquid quick-setting agent has many problems in terms of stability, economy, and product radiation range. In other words, in terms of practicality, the liquid quick-setting agent product still has significant limitations in application fields and transportation.

[0004] Chinese Patent CN110204238A discloses a water-soluble powdered alkali-free quick-setting agent and its preparation method. The quick-setting agent raw materials and the mass percentage of each component are: aluminum sulfate, lithium silicate, manganese fluorosilicate, pH adjuster, suspension stabilizer, and the balance is water, with the total amount made up to 100%. This invention has the following advantages: (1) it meets the alkali-free standard of GB / T35159-2017 "Quick-setting Agent for Shotcrete"; (2) it is a solid powder raw material in normal state, which is convenient for long-distance transportation; (3) it has very good water solubility when used; and (4) it has extremely high stability after use. However, this invention does not disclose the type of pH adjuster, and there is controversy about whether the pH adjuster is environmentally friendly.

[0005] To address the aforementioned problems, this invention has conducted in-depth research and development of an alkali-free and chloride-free powdered soluble accelerator. This accelerator uses sulfates and aluminum fluoride compounds as main raw materials, and through scientific formulation and refined preparation processes, achieves rapid setting and hardening while avoiding the introduction of alkali and chloride ions.

[0006] The above background information is provided only to aid in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0007] The purpose of this invention is to provide an alkali-free and chlorine-free powdered soluble accelerator, its preparation method, and its application method, so as to solve the technical problems of poor environmental performance, limited application fields, and high storage and transportation costs of the existing accelerators.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0009] A non-alkali and chlorine-free powdered soluble quick-setting agent, the base material is composed of sulfate and fluoroaluminate compounds, and other modified components are added; the mass percentage of the base material and each component is as follows: base material 45-60 wt.%, stabilizer 5-10 wt.%, polycarboxylic acid 3-5 wt.%, lignin sulfonate 5-10 wt.%, pH adjuster 1-1.5 wt.%, defoamer 5-8 wt.%, calcium formate 10-12 wt.%, and the balance is water.

[0010] Furthermore, the stabilizer includes one or any combination of low-viscosity hydroxypropyl methylcellulose, low-viscosity hydroxypropyl methylcellulose potassium, low-viscosity hydroxypropyl methylcellulose magnesium, and low-viscosity hydroxypropyl methylcellulose calcium.

[0011] Furthermore, the pH adjuster is any combination of lithium sulfate and diethylene glycolamine.

[0012] Furthermore, the defoamer includes any one or a combination of ammonium sulfate, aluminum sulfate, and magnesium sulfate.

[0013] Technical principle of the invention:

[0014] This invention incorporates low-viscosity hydroxypropyl methylcellulose, polycarboxylic acid, lignin sulfonate, lithium sulfate, and diethylene glycolamine to further enhance the performance of the accelerator. Low-viscosity hydroxypropyl methylcellulose improves the fluidity of concrete and reduces construction resistance. Polycarboxylic acid, another important additive, plays a dispersing and stabilizing role in the accelerator, adsorbing onto the surface of concrete particles to form a stable dispersion layer, effectively preventing particle agglomeration and sedimentation, thus ensuring the uniformity and stability of the concrete. Lignosulfonate, a natural polymer compound, not only possesses good water solubility and dispersibility, but its lignin sulfonate groups can also chelate with metal ions in concrete, further enhancing the stability and durability of the concrete.

[0015] The addition of lithium sulfate and diethylene glycolamine is to further optimize the setting and hardening effect of the accelerator. Lithium sulfate can enhance the compressive strength and durability of concrete, while diethylene glycolamine can adjust the setting time of concrete to better meet construction requirements.

[0016] This invention also takes into account the environmental performance of the accelerator, selecting low-pollution environmentally friendly materials to ensure that the accelerator will not cause pollution to the environment during use, while minimizing the generation of waste during construction.

[0017] In summary, the alkali-free and chlorine-free powdered soluble quick-setting agent developed in this invention not only has excellent setting and hardening properties, but also good environmental and construction performance. It will provide strong technical support for the development of the modern construction industry and promote the industry's continuous progress.

[0018] This invention also provides a method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent, comprising the following steps:

[0019] (1) Base material pretreatment: Sulfate and aluminum fluoride compound are ground into powder;

[0020] (2) Dissolving and mixing: After the water temperature in the reactor rises, the sulfate and fluorine-aluminum compound pretreated in step (1) are added to the reactor and then mixed and stirred for 0.5-1h until completely dissolved to obtain a mixture.

[0021] (3) Feeding: The mixture in the reactor in step (2) is guided to the vacuum stirrer through a special pipe. Stabilizer, polycarboxylic acid, lignin sulfonate, defoamer and calcium formate are added through the feeding port. Stirring is continued for 1-1.25 hours to obtain a uniform and stable mixture.

[0022] (4) Adjusting pH value: Add pH adjuster through the feed port to adjust the pH value of the liquid and obtain the quick-setting agent mother liquor;

[0023] (5) Decolorization treatment: Stop the feeding operation in step (4) and add decolorizing flocculant to the quick-setting agent mother liquor for decolorization treatment;

[0024] (6) Concentration and drying: The accelerator mother liquor is cooled by a vacuum stirrer and an external condenser. The accelerator mother liquor changes from liquid to semi-liquid and semi-solid state. Under the action of vacuum stirring and drying, it finally becomes solid accelerator powder. Then, it is dried to reduce the water content and obtain alkali-free and chlorine-free powdered soluble accelerator.

[0025] Furthermore, in step (1), the particle size of the sulfate and aluminum fluoride compound after grinding is 200-250 mesh.

[0026] Furthermore, the water temperature in step (2) is 60-95℃.

[0027] Furthermore, the pH value of the liquid in step (4) is controlled between 2 and 3.

[0028] Furthermore, the decolorizing flocculant in step (5) has a pH of 1.9 and a specific gravity of 1.180 g / cm³.3 .

[0029] This invention also provides a method for using an alkali-free and chlorine-free powdered masterbatch soluble accelerator. The method includes two approaches: First, the alkali-free and chlorine-free powdered masterbatch soluble accelerator is mixed with water at a mass ratio of 1:0.5-1.4 to prepare an alkali-free and chlorine-free liquid accelerator, which is used in shotcrete construction at a dosage of 6-9% of the cement mass. Second, the alkali-free and chlorine-free powdered masterbatch soluble accelerator is mixed with aluminum sulfate and water at a mass ratio of 2-5:1-4:4 to prepare an alkali-free and chlorine-free liquid accelerator, which is also used in shotcrete construction at a dosage of 6-9% of the cement mass.

[0030] The beneficial effects of this invention compared to the prior art include:

[0031] 1. The alkali-free and chlorine-free powdered soluble quick-setting agent of this invention has the advantages of being alkali-free, chlorine-free, and non-corrosive. Its chloride ion content is less than 0.1%, and its alkali content is less than 1%, meeting the alkali-free quick-setting agent standard of GB / T35159-2017 "Quick-setting Agent for Shotcrete". In addition, the weakly acidic quick-setting agent will not corrode the human body during construction operations, ensuring the personal safety and health of construction personnel.

[0032] 2. The alkali-free and chlorine-free powdered soluble quick-setting agent of this invention has a highly efficient setting-promoting effect, good crack resistance and impermeability. The quick-setting agent prepared by this invention can achieve a mortar strength of up to 28.1 MPa at 1 day, a mortar compressive strength ratio of up to 123% at 28 days, and a strength retention rate of up to 115% at 90 days. The product of this invention can be dissolved in water to obtain a liquid quick-setting agent for use in tunnel spraying construction, providing strong protection for the safety and stability of tunnels.

[0033] 3. The product of this invention has excellent stability and is easy to store for a long time. The alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent of this invention is in solid powder form, which avoids the precipitation or even crystallization phenomenon that easily occurs in liquid quick-setting agents during transportation and storage. After being stored in the warehouse for one year, its performance is hardly affected when reused. This solves the problem of the great limitations of liquid quick-setting agent products in terms of application fields and transportation.

[0034] 4. The alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent of the present invention can be immediately transformed into an alkali-free and chlorine-free liquid quick-setting agent by adding water and stirring in a certain proportion under normal temperature field conditions.

[0035] 5. The alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent of the present invention is environmentally friendly and efficient. It adopts environmentally friendly and non-corrosive modified functional additives. The product of the present invention exhibits strong adaptability to engineering cement at a low dosage and can meet the construction requirements of shotcrete. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0037] In an embodiment of the present invention, a non-alkali and chlorine-free powdered soluble quick-setting agent is provided, the base material of which is composed of aluminum sulfate and calcium fluoroaluminate, and other modified components are added; the mass percentage of the base material and each component is as follows: base material 45-60 wt.%, stabilizer 5-10 wt.%, polycarboxylic acid 3-5 wt.%, magnesium lignosulfonate 5-10 wt.%, pH adjuster 1-1.5 wt.%, defoamer 5-8 wt.%, calcium formate 10-12 wt.%, and the balance is water.

[0038] A method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent includes the following steps:

[0039] (1) Base material pretreatment: The particle size of aluminum sulfate and calcium fluoroaluminate after grinding is 200-250 mesh, and the aluminum sulfate and calcium fluoroaluminate are composed in a mass ratio of 3:1.

[0040] (2) Dissolving and mixing: After the water temperature in the reactor rises to 60-95℃, add the aluminum sulfate and calcium fluoroaluminate pretreated in step (1) into the reactor, and then mix and stir for 0.5-1h until completely dissolved to obtain a mixed solution;

[0041] (3) Feeding: The mixture in the reactor in step (2) is guided to the vacuum stirrer through a special pipe. Stabilizer, polycarboxylic acid, magnesium lignosulfonate, defoamer and calcium formate are added through the feeding port. Stirring is continued for 1-1.25 hours to obtain a uniform and stable mixture.

[0042] (4) Adjusting pH value: Add pH adjuster through the feed port to adjust the pH value of the liquid to 2-3 to obtain quick-setting agent mother liquor. The pH adjuster is composed of lithium sulfate and diethylene glycolamine in a mass ratio of 2:1.

[0043] (5) Decolorization treatment: Stop the feeding operation in step (4), and add a decolorizing flocculant to the quick-setting agent mother liquor for decolorization treatment. The decolorizing flocculant has a pH value of 1.9 and a specific gravity of 1.180 g / cm³. 3 ;

[0044] (6) Concentration and Drying: The accelerator mother liquor is cooled by a vacuum mixer with an external condenser, changing it from a liquid to a semi-liquid, semi-solid state. Under vacuum stirring and drying, it eventually becomes a solid accelerator powder, which is then dried to reduce the water content, resulting in an alkali-free and chlorine-free powdered soluble accelerator. There are two methods for using the obtained alkali-free and chlorine-free powdered soluble accelerator: First, the alkali-free and chlorine-free powdered soluble accelerator is mixed with water at a mass ratio of 1:0.5-1.4 to prepare an alkali-free and chlorine-free liquid accelerator, which is used in shotcrete construction at a dosage of 6-9% of the cement mass. Second, the alkali-free and chlorine-free powdered soluble accelerator is mixed with aluminum sulfate and water at a mass ratio of 2-5:1-4:4 to prepare an alkali-free and chlorine-free liquid accelerator, which is also used in shotcrete construction at a dosage of 6-9% of the cement mass.

[0045] To make the present invention more fully disclosed, more specific embodiments are described below.

[0046] The raw material formulations (excluding water) of the alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent in Examples 1-5 are shown in Table 1, and their preparation process parameters are shown in Table 2.

[0047] Table 1. Raw material formulation of alkali-free and chlorine-free powdered masterbatch soluble accelerator (balance: water)

[0048]

[0049] Table 2. Preparation process parameters of alkali-free and chlorine-free powdered masterbatch soluble accelerator

[0050]

[0051] The comparative example used was the water-soluble powdered alkali-free quick-setting agent prepared in Example 3 of the method in application publication number CN 110204238 A.

[0052] The alkali-free and chlorine-free powdered soluble accelerators prepared in Examples 1-5 were mixed with water at a mass ratio of 1:0.5-1.4 to prepare a conventional alkali-free and chlorine-free liquid accelerator. This liquid accelerator was added to cement paste or cement mortar samples at a weight of 6-9% of the cement. The setting time and compressive strength were tested according to GB / T35159-2017 "Accelerators for Shotcrete," the performance indicators required by this standard are shown in Table 3. A comparative example was used as a control, and a blank sample without any accelerator was used.

[0053] Table 3 Performance Requirements for Neat Cement and Mortar with Accelerators

[0054]

[0055] Table 4. Results of relevant performance tests

[0056]

[0057]

[0058] This invention provides a non-alkali and chloride-free powdered soluble accelerator with highly efficient setting-promoting effects, good crack resistance, impermeability, and environmental friendliness. This is due to the synergistic effect between aluminum sulfate and calcium fluoroaluminate in the accelerator's composition, which significantly promotes the rapid hardening and solidification of concrete. Aluminum sulfate, with its excellent reactivity, can rapidly react with cement to generate hydration products such as ettringite. These products fill the voids in concrete particles, enhancing the density and strength of the concrete. Calcium fluoroaluminate, through its unique chemical properties, further accelerates this reaction process, greatly shortening the concrete's setting time. In addition, low-viscosity sodium hydroxypropyl methylcellulose plays a role in reducing viscosity and improving fluidity in quick-setting agents. Through the hydroxypropyl and methyl groups in its molecular structure, it interacts with water and solid particles in concrete, effectively reducing the viscosity and improving its fluidity. Polycarboxylic acid can adsorb onto the surface of concrete particles, forming a stable dispersion layer, effectively preventing particle agglomeration and sedimentation, thus ensuring the uniformity and stability of the concrete. Magnesium lignosulfonate has good water solubility and dispersibility, and the lignosulfonate groups can chelate with metal ions in concrete, further enhancing the stability and durability of the concrete. Lithium sulfate can effectively adjust the pH value of concrete, thereby improving its hardening performance and durability. It can also react chemically with other components in concrete to generate new compounds, further enhancing the strength and stability of concrete. Diethylene glycol amine plays a buffering and regulating role in accelerators. It can neutralize acidic substances in concrete, thereby reducing the acidity of concrete and minimizing its erosion and damage to the concrete structure. It can also react chemically with other components in concrete to generate new compounds, further enhancing the stability and durability of concrete. Ammonium sulfate mainly plays a role in regulating concrete performance in accelerators. It can change the hardening speed and strength of concrete by reacting chemically with other components in concrete, thereby meeting different engineering requirements. Calcium formate can promote the setting and hardening process of cement. When calcium formate reacts with cement, it can promote the formation of some cement ettringite. In addition, calcium formate can also promote the formation of CSH crystal nuclei in cement. These compounds are important components of cement hardening.

[0059] The test results are shown in Table 4. The chloride ion content in each example is less than 0.1%, and the alkali content is less than 1%, classifying them as alkali-free and chloride-free accelerators. According to the standard analysis of GB / T35159-2017 "Accelerators for Shotcrete", the alkali-free accelerator prepared in this invention only needs a dosage of 6% to meet the standard requirements. For example, in Example 3, the mortar's 1-day compressive strength reached 28.1 MPa, the 28-day compressive strength ratio reached 123%, and the 90-day strength retention rate was as high as 115%. In the comparative example, the accelerator's setting time was acceptable, but its 1-day compressive strength was significantly lower than that of the example under the same experimental conditions. In contrast, the alkali-free and chloride-free powdered soluble accelerator prepared in this invention has a lower dosage and higher compressive strength, indicating that the performance of the alkali-free and chloride-free powdered soluble accelerator prepared in this invention is significantly better than that of the comparative product.

[0060] Table 5. Effect of storage time on the performance of accelerators from alkali-free and chlorine-free powdered masterbatches.

[0061]

[0062]

[0063] The experimental results are shown in Table 5. The results show that the alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent of the present invention, after being stored for one year, has almost the same setting time, strength and other properties as the product just produced, which fully demonstrates that the present invention has an ultra-long storage time.

[0064] Table 6. Compatibility of water-soluble powdered alkali-free accelerators with cement

[0065]

[0066] As shown in Table 6, the alkali-free and chloride-free powdered soluble accelerator of this invention can meet the construction requirements of shotcrete for different brands and types of cement at a relatively low dosage, demonstrating strong adaptability to engineering cement. This is because magnesium lignosulfonate is a natural polymer compound with excellent dispersibility and stability. In the accelerator, it can interact with the charge on the surface of cement particles to form a stable dispersion system, preventing the sedimentation and agglomeration of cement particles. Moreover, the lignosulfonate groups can chelate with metal ions in concrete, further enhancing the stability and durability of concrete and further improving the accelerator's setting-promoting effect.

[0067] The above content should not be construed as limiting the specific implementation of this invention to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of this invention, and all such deductions or substitutions should be considered as falling within the patent protection scope defined by the submitted claims.

Claims

1. A non-alkali and chlorine-free powdered masterbatch soluble quick-setting agent, characterized in that, The base material is composed of aluminum sulfate and calcium fluoroaluminate in a mass ratio of 3:1, with the addition of other modifying components; the mass percentages of the base material and each component are as follows: base material 45-60 wt.%, stabilizer 5-10 wt.%, polycarboxylic acid 3-5 wt.%, lignin sulfonate 5-10 wt.%, pH adjuster 1-1.5 wt.%, defoamer 5-8 wt.%, calcium formate 10-12 wt.%, and the balance being water; The stabilizer includes one or any combination of low-viscosity hydroxypropyl methylcellulose, low-viscosity hydroxypropyl methylcellulose potassium, low-viscosity hydroxypropyl methylcellulose magnesium, and low-viscosity hydroxypropyl methylcellulose calcium. The pH adjuster is any combination of lithium sulfate and diethylene glycolamine; The defoamer includes any one or a combination of ammonium sulfate, aluminum sulfate, and magnesium sulfate.

2. A method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent according to claim 1, characterized in that, Includes the following steps: (1) Base material pretreatment: Aluminum sulfate and calcium fluoroaluminate are ground into powder; (2) Dissolving and mixing: After the water temperature in the reactor rises, add the aluminum sulfate and calcium fluoroaluminate pretreated in step (1) into the reactor, and then mix and stir for 0.5-1h until completely dissolved to obtain a mixed solution; (3) Feeding: The mixture in the reactor of step (2) is guided to the vacuum stirrer through a special pipe. Stabilizer, polycarboxylic acid, lignin sulfonate, defoamer and calcium formate are added through the feeding port. Stirring is continued for 1-1.25 hours to obtain a uniform and stable mixture. (4) Adjusting pH value: Add pH adjuster through the feed port to adjust the pH value of the liquid and obtain the quick-setting agent mother liquor; (5) Decolorization treatment: Stop the feeding operation in step (4) and add decolorizing flocculant to the quick-setting agent mother liquor for decolorization treatment; (6) Concentration and drying: The accelerator mother liquor is cooled by a vacuum stirrer and an external condenser. The accelerator mother liquor changes from liquid to semi-liquid and semi-solid state. Under the action of vacuum stirring and drying, it finally becomes solid accelerator powder. Then, it is dried to reduce the water content and obtain alkali-free and chlorine-free powdered soluble accelerator.

3. The method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent according to claim 2, characterized in that: In step (1), the particle size of aluminum sulfate and calcium fluoroaluminate after grinding is 200-250 mesh.

4. The method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent according to claim 2, characterized in that: The water temperature in step (2) is 60-95℃.

5. The method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent according to claim 2, characterized in that: The pH value of the liquid in step (4) is controlled between 2 and 3.

6. The method for preparing an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent according to claim 2, characterized in that: The decolorizing flocculant has a pH of 1.9 and a specific gravity of 1.180 g / cm³. 3 .

7. A method for using an alkali-free and chlorine-free powdered masterbatch soluble quick-setting agent prepared according to any one of claims 2-6, characterized in that: There are two methods of use. The first method is to prepare an alkali-free and chlorine-free liquid accelerator by mixing the alkali-free and chlorine-free powdered masterbatch soluble accelerator with water at a mass ratio of 1:0.5-1.

4. This accelerator is then used in shotcrete construction, and its dosage is 6-9% of the cement mass. The second method is to prepare an alkali-free and chlorine-free liquid accelerator by mixing the alkali-free and chlorine-free powdered masterbatch soluble accelerator with aluminum sulfate and water at a mass ratio of 2-5:1-4:

4. This accelerator is also used in shotcrete construction, and its dosage is 6-9% of the cement mass.

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