Low-alkali chloride-free powdery master batch soluble accelerator and preparation process thereof

Abstract

The invention discloses a low-alkali chloride-free powdery master batch soluble accelerator and a preparation process thereof, and relates to the technical field of building materials. The high-temperature-resistant water-based paint comprises the following raw materials in percentage by mass: 2%-5% of sodium aluminate, 23%-35% of aluminum sulfate, 5%-10% of aluminum hydroxide, 5%-10% of silica sol, 0.5%-1.5% of triethanolamine, 3%-8% of borax, 0.5%-2% of a thickening agent, 1%-3% of a dispersing agent, 1.6%-1.8% of a pH regulator, 1.5%-2.0% of a complexing agent and the balance of water. The preparation process comprises the steps of dissolving and mixing, mixing reaction, additive adding and post-treatment. The prepared low-alkali chlorine-free powdery master batch soluble accelerator has the characteristics of high adaptability, good stability, convenience in storage and transportation and the like, and when the accelerator is applied to concrete, the mechanical property of the concrete can be remarkably improved, and higher application requirements can be met.

Description

[Technical field]

[0001] The invention relates to the technical field of building materials, in particular to a low-alkali chlorine-free powdered masterbatch soluble quick-setting agent and a preparation process thereof. [Background technology]

[0002] In a series of complex and critical underground and open-pit projects such as tunneling, mine shaft excavation and slope support, shotcrete operations play a vital role, and accelerators, as the core additives in this process, are indispensable. They can cause concrete to set and harden quickly in a short period of time, thereby effectively meeting the urgent needs of the project for early strength and strict construction timeliness requirements, ensuring that both project progress and quality standards are met.

[0003] However, the use of traditional accelerators is not perfect. The current accelerators are mainly divided into three categories according to the alkali content: alkali, low alkali and alkali-free. Alkali accelerators have serious late strength loss and poor stability; alkali-free accelerators have high dosage and are sensitive to temperature. Although low-alkali accelerators have better performance and can combine the advantages of high late strength retention rate and economy, they still have problems such as large differences in adaptability to different cements and mineral admixtures, poor compatibility with other admixtures, few manufacturers resulting in poor product quality stability, extended accelerating time, insufficient late strength guarantee rate and high dosage. In addition, traditional accelerators contain chloride ions, which pose a huge threat to the steel bars inside the concrete. It will accelerate the corrosion process of the steel bars, thereby reducing the bearing capacity of the entire structure and shortening its service life.

[0004] In addition, traditional accelerators also have many inconveniences in form. Although liquid accelerators are easy to use, they face problems such as easy precipitation and stratification and poor stability during storage and transportation, which brings considerable trouble to construction. Although powdered accelerators are easy to transport and store, they are difficult to disperse evenly in concrete, which affects the quick-setting effect and makes it difficult for the setting time and strength development of concrete to meet expectations.

[0005] Therefore, in view of the above problems, it is particularly important to develop a low-alkali, chlorine-free and well-soluble powdered accelerator masterbatch. This accelerator can not only effectively avoid the hazards of high-alkali aggregate reaction and chloride ion corrosion, improve the durability of concrete and the safety of the structure, but also ensure the uniform dispersion of the accelerator in the concrete, exert the best quick-setting effect, and provide more reliable technical support for the spraying concrete operation of underground and open-air projects.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. [Summary of the invention]

[0007] The present invention aims to provide a low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent and a preparation process thereof, so as to solve the technical problems existing in the above-mentioned prior art.

[0008] To this end, the present invention adopts the following technical solutions:

[0009] A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, comprising the following raw materials in percentage by mass:

[0010] Sodium aluminate 2%-5%, aluminum sulfate 23%-35%, aluminum hydroxide 5%-10%, silica sol 5%-10%, triethanolamine 0.5%-1.5%, borax 3%-8%, thickener 0.5%-2%, dispersant 1%-3%, pH adjuster 1.6%-1.8%, complexing agent 1.5%-2.0%, and the balance is water.

[0011] Furthermore, the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent is made of the following raw materials in percentage by mass:

[0012] Sodium aluminate 3%, aluminum sulfate 27%, aluminum hydroxide 7.2%, silica sol 7.5%, triethanolamine 1.2%, borax 5.5%, thickener 1.2%, dispersant 1.8%, pH adjuster 1.7%, complexing agent 1.8%, and the balance is water.

[0013] Furthermore, the thickener is hydroxypropyl methylcellulose.

[0014] Furthermore, the dispersant is one or more of amine-modified lignin and ammonium polyacrylate.

[0015] Furthermore, the pH adjuster is one or more of citric acid and tartaric acid.

[0016] Furthermore, the complexing agent is prepared by a mixed reaction of N-methyl-2-acrylamide, cyclohexylmethyldimethoxysilane, β-aminoethanesulfonic acid, cyclohexanone peroxide, carotene and water.

[0017] The design principle of the raw material composition of the accelerator described in the present invention is as follows:

[0018] Sodium aluminate: Sodium aluminate can ionize aluminum ions Al in aqueous solution 3+Aluminum ions can participate in the hydration reaction of cement, accelerate the hydration process of mineral components, and promote the rapid formation and crystallization of hydration products, thereby shortening the setting time of concrete. At the same time, sodium aluminate, aluminum sulfate and other raw materials work together to promote the setting and hardening of concrete and improve its early strength.

[0019] Aluminum hydroxide: Aluminum hydroxide plays a unique role in the accelerator system. At room temperature, it has a certain chemical stability, but under the alkaline environment generated by cement hydration and the interaction with other raw materials, aluminum hydroxide will gradually react. It can decompose and release aluminum ions Al 3+ , these aluminum ions can participate in the hydration reaction process of cement. Unlike the direct use of sodium aluminate and aluminum sulfate to provide aluminum ions, aluminum hydroxide releases aluminum ions at a relatively slow and continuous rate. In the early stage of concrete coagulation, it can replenish the aluminum ions consumed by other rapid reactions, so that the cement hydration reaction can maintain a certain activity for a long time, which helps to optimize the coagulation process of concrete, make the coagulation more uniform, and reduce the problem of uneven concrete structure that may be caused by sudden changes in aluminum ion concentration. Aluminum hydroxide also reacts synergistically with other components during the reaction process, jointly affecting the formation and structure of cement hydration products. It can combine with sulfate ions and the like to change the generation rate and crystal morphology of products such as calcium aluminate to a certain extent, thereby affecting the early strength development and microstructure of concrete. In this way, aluminum hydroxide helps to improve the early strength of concrete, and also has a positive effect on the continuous growth of later strength, so that concrete can maintain good mechanical properties for a long time.

[0020] Silica sol: Silica sol plays a role in promoting the development of early strength. The main component of silica sol is silicon dioxide, which can react with alkaline substances in the system to generate substances such as calcium silicate with gelling properties, thereby enhancing the setting effect of the accelerator. Silicon dioxide reacts chemically with alkaline substances in the system to generate substances such as calcium silicate (CaSiO3) with gelling properties. It can also react with calcium ions in cement to generate calcium silicate hydrate (CSH) gel, which can not only fill the internal pores of concrete and improve the density of concrete, but also enhance the bonding force between cement stone and aggregate, thereby significantly improving the early strength of concrete, enabling it to reach a certain bearing capacity in a short time, and meeting the requirements of rapid construction and early support of shotcrete.

[0021] Triethanolamine: Triethanolamine molecules contain active groups such as amino and hydroxyl groups, which play a key role in the cement hydration process. They can be adsorbed on the surface of cement particles, reduce the surface energy of cement particles, and then promote the dissolution of cement mineral components and promote the hydration reaction. Among the many mineral components of cement, triethanolamine has a significant effect on the hydration reaction of tricalcium aluminate. It can accelerate the hydration reaction of tricalcium aluminate, promote the formation of more hydrated calcium aluminate crystals, and provide support for the rapid development of cement hydration systems. At the same time, the complex formed by aluminum ions and triethanolamine can change the hydration reaction path of tricalcium aluminate, reduce the activation energy of the reaction, and greatly accelerate the hydration reaction rate of tricalcium aluminate. Not only that, there is a synergistic effect between silicate ions and triethanolamine, which can promote the formation of hydrated calcium silicate (CSH) gel. Moreover, triethanolamine can effectively shorten the setting time of concrete and significantly improve its early strength at a lower dosage.

[0022] Borax: Borax hydrolyzes in aqueous solution to produce borate ions, which can react with calcium ions in cement hydration products, change the structure and morphology of cement hydration products, form a more compact and stable structure, and promote early coagulation of concrete. At the same time, borax itself is a low-alkali substance, which meets the design requirements of low-alkali and chlorine-free accelerators, does not introduce too many alkali metal ions, and avoids the occurrence of alkali-aggregate reaction.

[0023] Thickener: Thickeners prevent precipitation and stratification. Hydroxypropyl methylcellulose (HPMC) has good water solubility and thickening properties as a thickener. After the masterbatch is compounded into an accelerator solution, they can increase the viscosity of the solution, form a stable colloidal structure, and ensure that the components of the accelerator are evenly dispersed. This is not only beneficial to the storage stability of the accelerator, but also ensures that the accelerator is evenly dispersed in the concrete when used, so that the quick-setting effect is consistent and the uniformity of the concrete quality is improved. The addition amount of thickener is between 0.5% and 2%, which can achieve a good thickening effect without negatively affecting other properties of the accelerator.

[0024] Dispersant: The function of dispersant is to improve the dispersibility of raw materials. Amine-modified lignin and ammonium polyacrylate as dispersants can be adsorbed on the surface of raw material particles, reduce the surface energy of particles, and prevent agglomeration between particles through electrostatic repulsion and steric hindrance. In the preparation process of accelerator, ensure that all raw materials are evenly dispersed, improve the reactivity and solubility of raw materials, and make the performance of accelerator more stable and reliable. The addition amount of dispersant is 1%-3%, which is adjusted according to the characteristics of raw materials and process requirements to achieve the best dispersion effect.

[0025] pH regulator: Both citric acid and tartaric acid are organic acids, which contain multiple acidic functional groups. In the accelerator system, when the pH regulator is added, these acidic functional groups will ionize hydrogen ions. The hydrogen ions combine with the hydroxide ions in the system, thereby lowering the pH value of the solution. By controlling the amount of pH regulator added, the pH value of the accelerator system can be accurately adjusted within an appropriate range. In the cement hydration reaction, the appropriate pH value helps to activate the active ingredients in the cement and promote its dissolution and hydration reaction. They can effectively reduce the alkalinity of the accelerator. Under the premise of ensuring that the other properties of the accelerator are not significantly affected, the alkali metal ions are converted into relatively stable salts by reacting with alkaline substances, thereby reducing the content of alkali metal oxides (measured in sodium oxide equivalent), ensuring that the alkali content of the accelerator meets the low alkali requirements. This is of great significance for preventing concrete alkali-aggregate reaction and improving the durability of concrete. In addition, precise control of pH value can also avoid the adverse effects on concrete performance caused by too high or too low pH. For example, too high pH may lead to alkali-aggregate reaction, and too low pH may inhibit cement hydration reaction.

[0026] Complexing agent: The complexing agent is made by mixing and reacting N-methyl-2-acrylamide, cyclohexylmethyldimethoxysilane, β-aminoethanesulfonic acid, cyclohexanone peroxide, carotene and water. Among them, organic components such as N-methyl-2-acrylamide form complexes with metal ions (such as aluminum ions), change the existence state and reaction activity of metal ions, and optimize the accelerating effect and performance stability of the accelerator. Cyclohexylmethyldimethoxysilane and other components play a certain surface modification role in concrete and enhance the interfacial bonding force inside the concrete. β-aminoethanesulfonic acid and other components participate in regulating the chemical balance of the system, further improving the adaptability of the accelerator to materials such as cement. Cyclohexanone peroxide and carotene and other components have certain antioxidant and stabilizing effects, preventing the raw materials from deteriorating or deteriorating in performance, thereby ensuring the stability and effectiveness of the accelerator during storage and use. The amount of complexing agent added to the accelerator is 1.5%-2.0%, and through the synergistic effect with other raw materials, the comprehensive performance of the accelerator is comprehensively improved.

[0027] A preparation process of a low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent comprises the following steps:

[0028] (1) Dissolving and mixing: sodium aluminate, aluminum sulfate and water are added to a reaction kettle equipped with a stirring device and a heating device, and stirring and heating are started at the same time; after the mixture is evenly mixed, aluminum hydroxide is added and the mixture is reacted for 30-60 minutes at the same temperature and stirring rate;

[0029] (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 15-30 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 60-70° C. and maintaining the same stirring rate for 20-40 min;

[0030] (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent, and heat and stir for 5-10 minutes after each raw material is added to finally generate a water-containing solid;

[0031] (4) Post-treatment: The generated water-containing solid is dried with a drying device. After drying, the grinding device is turned on for grinding to obtain the accelerator masterbatch powder, which is packaged and stored to obtain a low-alkali, chlorine-free powdery soluble accelerator masterbatch finished product.

[0032] Furthermore, in step (1), the stirring rate is 500-600 r / min, and the reaction kettle is heated to 40-60° C.

[0033] Furthermore, the heating in step (3) is to increase the temperature to 75-80°C.

[0034] Furthermore, the stirring rate in step (3) is 200-300 r / min.

[0035] Furthermore, in step (4), the grinding accuracy of the grinding device is set to a particle size of 80-200 meshes.

[0036] The preparation process and technical principle of the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent is as follows:

[0037] Dissolving and mixing: After sodium aluminate, aluminum sulfate and water are heated and stirred to mix evenly, aluminum hydroxide is added and reacted for 30-60 minutes at the same temperature and stirring rate. The purpose of stirring is to fully mix sodium aluminate, aluminum sulfate and water to form a uniform system to ensure that sodium aluminate and aluminum sulfate can be evenly dissolved in water. Heating is to speed up the dissolution rate of sodium aluminate and aluminum sulfate, while increasing the activity of molecules and promoting subsequent reactions. Higher temperatures can make molecular motion more intense, increase the probability of collision between reactants, and thus accelerate the rate of chemical reactions. At the same time, the slow dissolution and reaction process of aluminum hydroxide also helps to control the progress and rate of the reaction, providing a stable source of aluminum ions for subsequent reactions.

[0038] Mixing reaction: The main component of silica sol is silicon dioxide, which can react with alkaline substances in the system to generate substances such as calcium silicate with gelling properties, thereby enhancing the setting effect of the accelerator. Borax can change the structure and morphology of cement hydration products in the system and promote the early setting of cement. Slowly adding and fully stirring can ensure that they fully react with other components in the system to form a uniform mixed system. Silica sol provides the basic silicon-oxygen tetrahedral structural unit for the formation of the coagulation skeleton, while the borax hydrolysis product optimizes the structure of the coagulation skeleton through complexation with calcium ions, making the coagulation process of concrete faster and more stable. Add triethanolamine solution at 60-70℃ and react for 20-40min. Triethanolamine has the function of promoting the dissolution and hydration reaction of cement minerals. In this temperature range, its activity is relatively high, and it has a synergistic effect with aluminum ions, silicate ions, etc. in the system. The complex formed by aluminum ions and triethanolamine can change the hydration reaction path of tricalcium aluminate, reduce the activation energy of the reaction, and thus accelerate the hydration reaction rate of tricalcium aluminate. The synergistic effect between silicate ions and triethanolamine promoted the formation of calcium silicate hydrate (CSH) gel.

[0039] Adding additives: Add pH regulator at 75-80℃ to adjust the pH value of the system to create a suitable acid-base environment for subsequent chemical reactions. Different chemical reactions have the best reaction rate and effect within a specific pH range. Add thickener, dispersant and complexing agent at a stirring rate of 500-600r / min and stir for 5-10min respectively. Thickener can increase the viscosity of the system, form a three-dimensional network structure through intermolecular interaction, effectively prevent precipitation and stratification, and keep the accelerator uniform and stable during storage and use. Dispersant adsorbs on the surface of raw material particles through electrostatic repulsion and steric hindrance, and synergizes with thickener to ensure that various raw material particles are evenly dispersed in the system, avoiding the occurrence of agglomeration, thereby improving the uniformity and efficiency of the reaction. Complexing agent reacts with metal ions (such as aluminum ions) in the system, and adjusts their activity and existence form by changing the electron cloud distribution and coordination environment of metal ions, thereby enhancing the compatibility of accelerator with materials such as cement, and synergizing with other additives to optimize the performance of accelerator.

[0040] Post-processing: Use drying equipment to dry the water-containing solids, grind the dried materials to 80-200 mesh, further refine the particles, make them more soluble and dispersible, and facilitate rapid and uniform dissolution when they are subsequently prepared into accelerator solution.

[0041] The beneficial effects of the present invention include:

[0042] 1. Excellent quick-setting performance: Multiple accelerating coagulation components work synergistically, sodium aluminate and aluminum sulfate provide aluminum ions, aluminum hydroxide continuously releases aluminum ions, sodium aluminate and aluminum sulfate generate calcium sulfate, and triethanolamine promotes early strength, etc., which can effectively meet the construction requirements of rapid coagulation of shotcrete. This not only improves construction efficiency and reduces construction time, but also provides early support strength for the project in a timely manner, enhancing the safety and stability of the project.

[0043] 2. High late strength retention rate: The rational use of aluminum hydroxide, silica sol and other ingredients not only contributes to the rapid development of early strength of concrete, but also ensures the continuous growth of late strength. The 28-day compressive strength ratio of concrete can reach more than 100%, and the 90-day compressive strength retention rate is greater than 95%, ensuring the bearing capacity and stability of the concrete structure during long-term use.

[0044] 3. Good adaptability and stability: The low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent prepared by the present invention can adapt to various types of cement and mineral admixtures, and has good compatibility with other admixtures (such as water reducers, air entraining agents, etc.). Under different engineering environments and material conditions, it can stably play a role in quick setting, ensuring the quality uniformity and performance stability of concrete. It avoids the engineering quality risks caused by material adaptability problems. At the same time, the powdered masterbatch form is easy to store and transport, has good stability under different environmental conditions, is not easy to deteriorate or fail, has good solubility in water, high solution stability, and no precipitation or stratification after long-term storage, ensuring the long-term availability of the product.

[0045] 4. Environmentally friendly and chlorine-free: It contains no chloride ions, which eliminates the risk of chloride ion corrosion on steel bars, ensures the long-term stability of steel bars in reinforced concrete structures, extends the service life of concrete structures, reduces construction waste generated by structural damage, and meets the requirements of environmental protection and sustainable development.

[0046] 5. Improved overall performance: The presence of the complexing agent optimizes the synergistic effect between the components of the accelerator, enhances the adaptability of the accelerator to materials such as cement, and improves the stability and effectiveness of the product. The thickener and dispersant ensure the uniformity and stability of the accelerator during preparation, storage and use, making the quick-setting effect consistent and improving the uniformity of concrete quality. These factors work together to make the accelerator of the present invention have obvious advantages in overall performance, can meet the requirements of various complex engineering environments and high-standard engineering quality, and provide a high-performance and reliable accelerator product for the construction engineering industry. [Specific implementation method]

[0047] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0048] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0049] In an embodiment of the present invention, the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent is made of the following raw materials in percentage by mass:

[0050] Sodium aluminate 2%-5%, aluminum sulfate 23%-35%, aluminum hydroxide 5%-10%, silica sol 5%-10%, triethanolamine 0.5%-1.5%, borax 3%-8%, thickener 0.5%-2%, dispersant 1%-3%, pH adjuster 1.6%-1.8%, complexing agent 1.5%-2.0%, and the balance is water.

[0051] The thickener is hydroxypropyl methylcellulose.

[0052] The dispersant is one or more of amine-modified lignin and ammonium polyacrylate.

[0053] The pH adjuster is one or more of citric acid and tartaric acid.

[0054] The complexing agent is prepared by mixing N-methyl-2-acrylamide, cyclohexylmethyldimethoxysilane, beta-aminoethanesulfonic acid, cyclohexanone peroxide, carotene and water.

[0055] The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent comprises the following steps:

[0056] (1) Dissolving and mixing: adding sodium aluminate, aluminum sulfate and water into a reaction kettle equipped with a stirring device and a heating device, stirring and heating at the same time, the stirring rate is 500-600 r / min, and the reaction kettle is heated to 40-60° C.; after mixing evenly, adding aluminum hydroxide, reacting at the same temperature and stirring rate for 30-60 min;

[0057] (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 15-30 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 60-70° C. and maintaining the same stirring rate for 20-40 min;

[0058] (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent. After each raw material is added, stir at 75-80° C. for 5-10 minutes at a stirring rate of 200-300 r / min to generate a water-containing solid.

[0059] (4) Post-treatment: The generated water-containing solid is dried with a drying device, and after drying, a grinding device is turned on for grinding to obtain an accelerator masterbatch powder; the grinding accuracy of the grinding device is set to a particle size of 80-200 mesh, and the product is packaged and stored to obtain a low-alkali, chlorine-free powdery soluble accelerator masterbatch finished product.

[0060] In order to make the disclosure of the present invention more complete, it is described below through more specific embodiments.

[0061] Example 1

[0062] A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, comprising the following raw materials in percentage by mass:

[0063] Sodium aluminate 3%, aluminum sulfate 27%, aluminum hydroxide 7.2%, silica sol 7.5%, triethanolamine 1.2%, borax 5.5%, thickener 1.2%, dispersant 1.8%, pH adjuster 1.7%, complexing agent 1.8%, and the balance is water.

[0064] The thickener is hydroxypropyl methylcellulose.

[0065] The dispersant is amino-modified lignin.

[0066] The pH adjuster is tartaric acid.

[0067] The complexing agent is prepared by mixing N-methyl-2-acrylamide, cyclohexylmethyldimethoxysilane, β-aminoethanesulfonic acid, cyclohexanone peroxide, carotene and water; the preparation steps of the complexing agent are as follows:

[0068] (1) 42 parts of N-methyl-2-acrylamide, 10 parts of cyclohexylmethyldimethoxysilane, 70 parts of β-aminoethanesulfonic acid, 1.5 parts of cyclohexanone peroxide and 360 parts of water were mixed, and then reacted for 50 minutes under the conditions of controlling the speed to 200 r / min, the microwave power to 300 W, and the temperature to 38° C. to obtain a reaction mixture;

[0069] (2) Add 0.5 parts of carotene and 90 parts of water to the reaction mixture obtained in step (1), and then react for 60 minutes at a speed of 300 r / min, a microwave power of 200 W, and a temperature of 42° C., and then cool to room temperature to obtain a complexing agent.

[0070] The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent comprises the following steps:

[0071] (1) Dissolving and mixing: sodium aluminate, aluminum sulfate and water are added to a reaction kettle equipped with a stirring device and a heating device, stirring and heating are started at the same time, the stirring rate is 550 r / min, and the reaction kettle is heated to 50° C. After mixing evenly, aluminum hydroxide is added, and the reaction is carried out at the same temperature and stirring rate for 45 minutes;

[0072] (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 20 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 65° C. and maintaining the same stirring rate for 35 min;

[0073] (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent. After each raw material is added, stir at 78° C. for 10 min at a stirring rate of 300 r / min to generate a water-containing solid.

[0074] (4) Post-treatment: The generated water-containing solid is dried with a drying device, and after drying, a grinding device is turned on for grinding to obtain an accelerator masterbatch powder; the grinding accuracy of the grinding device is set to a particle size of 120 mesh, and the powder is packaged and stored to obtain a low-alkali, chlorine-free powdered soluble accelerator masterbatch finished product.

[0075] Example 2

[0076] A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, comprising the following raw materials in percentage by mass:

[0077] Sodium aluminate 2.5%, aluminum sulfate 24%, aluminum hydroxide 8%, silica sol 8.5%, triethanolamine 1.1%, borax 6.3%, thickener 1.5%, dispersant 2.2%, pH adjuster 1.6%, complexing agent 1.9%, and the balance is water.

[0078] The thickener is hydroxypropyl methylcellulose.

[0079] The dispersant is ammonium polyacrylate.

[0080] The pH adjuster is citric acid.

[0081] The preparation method of the complexing agent is consistent with that of Example 1.

[0082] The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent comprises the following steps:

[0083] (1) Dissolving and mixing: Sodium aluminate, aluminum sulfate and water are added to a reaction kettle equipped with a stirring device and a heating device, stirring and heating are started at the same time, the stirring rate is 520 r / min, and the reaction kettle is heated to 45° C. After mixing evenly, aluminum hydroxide is added and reacted at the same temperature and stirring rate for 50 min;

[0084] (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 25 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 62° C. and maintaining the same stirring rate for 30 min;

[0085] (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent. After each raw material is added, stir at 76° C. for 8 minutes at a stirring rate of 280 r / min to generate a water-containing solid.

[0086] (4) Post-treatment: The generated water-containing solid is dried with a drying device, and after drying, a grinding device is turned on for grinding to obtain an accelerator masterbatch powder; the grinding accuracy of the grinding device is set to a particle size of 100 mesh, and the product is packaged and stored to obtain a low-alkali, chlorine-free powdered soluble accelerator masterbatch finished product.

[0087] Example 3

[0088] A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, comprising the following raw materials in percentage by mass:

[0089] Sodium aluminate 3%, aluminum sulfate 30%, aluminum hydroxide 6%, silica sol 6%, triethanolamine 1.5%, borax 4.2%, thickener 0.8%, dispersant 1.5%, pH adjuster 1.8%, complexing agent 1.6%, and the balance is water.

[0090] The thickener is hydroxypropyl methylcellulose.

[0091] The dispersant is ammonium polyacrylate.

[0092] The pH adjuster is citric acid.

[0093] The preparation method of the complexing agent is consistent with that of Example 1.

[0094] The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent comprises the following steps:

[0095] (1) Dissolving and mixing: Sodium aluminate, aluminum sulfate and water are added to a reaction kettle equipped with a stirring device and a heating device, stirring and heating are started at the same time, the stirring rate is 580 r / min, and the reaction kettle is heated to 55° C. After mixing evenly, aluminum hydroxide is added, and the reaction is carried out at the same temperature and stirring rate for 35 minutes;

[0096] (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 20 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 68° C. and maintaining the same stirring rate for 25 min;

[0097] (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent. After each raw material is added, stir at 80° C. for 6 minutes at a stirring rate of 220 r / min to finally generate a water-containing solid.

[0098] (4) Post-treatment: The generated water-containing solid is dried with a drying device, and after drying, a grinding device is turned on for grinding to obtain an accelerator masterbatch powder; the grinding accuracy of the grinding device is set to a particle size of 150 mesh, and the powder is packaged and stored to obtain a low-alkali, chlorine-free powdery soluble accelerator masterbatch finished product.

[0099] Comparative Example 1

[0100] It is basically the same as Example 1, except that no thickener, dispersant or complexing agent is added to the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, and the balance is supplemented with water.

[0101] Comparative Example 2

[0102] It is basically the same as Example 1, except that no thickener is added to the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, and the balance is supplemented with water.

[0103] Comparative Example 3

[0104] It is basically the same as Example 1, except that no dispersant is added to the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, and the balance is supplemented with water.

[0105] Comparative Example 4

[0106] It is basically the same as Example 1, except that no complexing agent is added to the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, and the balance is supplemented with water.

[0107] The low-alkali chlorine-free powdered masterbatch soluble quick-setting agent prepared in Examples 1-3 and Comparative Examples 1-4 was added with water and stirred to form a low-alkali chlorine-free liquid quick-setting agent. The compounded liquid quick-setting agent was tested for setting time, compressive strength and stability of concrete added with the compounded quick-setting agent according to the standard GB / T35159-2017 "Accelerator for Shotcrete". The test results are shown in the following table, wherein the dosage of the liquid quick-setting agent is 6% of the quality of the adhesive.

[0108]

[0109] Among them, “√” represents no stratification phenomenon.

[0110] It can be seen from the experimental data that the initial coagulation time of comparative example 1 is 3:56, and the final coagulation time is 7:10; the initial coagulation time of comparative example 2 is 3:23, and the final coagulation time is 6:36; the initial coagulation time of comparative example 3 is 3:29, and the final coagulation time is 6:42; the initial coagulation time of comparative example 4 is 3:37, and the final coagulation time is 6:50. Compared with the embodiments, the coagulation time of the comparative examples is significantly prolonged. The thickener can make the solution form a stable colloidal structure, ensure the uniform distribution of the raw materials, and promote the rapid reaction to shorten the coagulation time. The lack of thickener in comparative example 2 causes the precipitation of the raw materials and the delay of the reaction; the dispersant can make the raw material particles evenly dispersed, increase the contact area and improve the reaction activity. The lack of dispersant in comparative example 3 causes the particles to agglomerate, affecting the coagulation; the complexing agent can optimize the performance of the components and adjust the activity of the metal ions. The lack of complexing agent in comparative example 4 affects the activity of the metal ions and the reaction efficiency, and the coagulation time is prolonged.

[0111] In terms of mortar strength, the 1d compressive strength of Comparative Example 1 is 9.5 MPa, the 28d compressive strength ratio is 90.5%, and the 90d compressive strength retention rate is 88.1%; the 1d compressive strength of Comparative Example 2 is 10.1 MPa, the 28d compressive strength ratio is 92.6%, and the 90d compressive strength retention rate is 89.3%; the 1d compressive strength of Comparative Example 3 is 10.2 MPa, the 28d compressive strength ratio is 95.1%, and the 90d compressive strength retention rate is 93.2%; the 1d compressive strength of Comparative Example 4 is 9.9 MPa, the 28d compressive strength ratio is 91.5%, and the 90d compressive strength retention rate is 88.7%, which are all much lower than the embodiments. Thickeners help cement hydration reaction to be uniform and sufficient, which is beneficial to strength development. Comparative Example 2 lacks thickeners, resulting in insufficient hydration and limited strength. Dispersants enable the components to react better with cement minerals and enhance the structure. Comparative Example 3 does not add dispersants, resulting in a loose internal structure and affected strength. Complexing agents adjust the activity of metal ions and optimize the product structure. Comparative Example 4 lacks complexing agents, resulting in poor reaction progress and product structure, and reduced strength.

[0112] In terms of stability, Comparative Example 1 separated 15 mL at 90 days, Comparative Example 2 separated 10 mL, Comparative Example 3 separated 7 mL, Comparative Example 4 separated 4 mL, and the Example did not separate. The thickener increases the viscosity and stability of the solution and prevents precipitation. Comparative Example 2 does not have a thickener, resulting in poor stability and severe precipitation and separation. The dispersant prevents particle agglomeration and precipitation and maintains uniformity. Comparative Example 3 does not have a dispersant and separates. The complexing agent also has a certain effect on the stability of the system. Comparative Example 4 does not have a complexing agent, resulting in poor stability.

[0113] In summary, thickeners, dispersants and complexing agents are indispensable in the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent. They work synergistically to ensure the high efficiency and good stability of the quick-setting agent from many aspects. The lack of any one or more of them will cause the quick-setting agent to perform poorly in terms of setting time, mortar strength and stability, and fail to achieve the excellent performance of the embodiment. Therefore, when preparing the quick-setting agent, the addition of these additives is very necessary to meet the requirements of engineering applications.

[0114] Those skilled in the art will recognize that numerous variations to the above description are possible, and that the examples are intended only to describe one or more specific implementations.

[0115] Although what is considered as exemplary embodiments of the present invention has been described and described, it will be understood by those skilled in the art that various changes and substitutions may be made thereto without departing from the spirit of the present invention. In addition, many modifications may be made to adapt specific situations to the teachings of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but the present invention may also include all embodiments and their equivalents that fall within the scope of the present invention.

Claims

1. A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent, characterized in that: The invention is made of the following raw materials in percentage by weight: Sodium aluminate 2%-5%, aluminum sulfate 23%-35%, aluminum hydroxide 5%-10%, silica sol 5%-10%, triethanolamine 0.5%-1.5%, borax 3%-8%, thickener 0.5%-2%, dispersant 1%-3%, pH adjuster 1.6%-1.8%, complexing agent 1.5%-2.0%, and the balance is water.

2. The low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent according to claim 1, characterized in that: The invention is made of the following raw materials in percentage by weight: Sodium aluminate 3%, aluminum sulfate 27%, aluminum hydroxide 7.2%, silica sol 7.5%, triethanolamine 1.2%, borax 5.5%, thickener 1.2%, dispersant 1.8%, pH adjuster 1.7%, complexing agent 1.8%, and the balance is water.

3. A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent according to claim 1 or 2, characterized in that: The thickener is hydroxypropyl methylcellulose.

4. A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent according to claim 1 or 2, characterized in that: The dispersant is one or more of amine-modified lignin and ammonium polyacrylate.

5. A low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent according to claim 1 or 2, characterized in that: The pH adjuster is one or more of citric acid and tartaric acid.

6. A process for preparing the low-alkali, chlorine-free powdered masterbatch soluble quick-setting agent according to claims 1-5, characterized in that: The following steps are involved: (1) Dissolving and mixing: sodium aluminate, aluminum sulfate and water are added to a reaction kettle equipped with a stirring device and a heating device, and stirring and heating are started at the same time; after the mixture is evenly mixed, aluminum hydroxide is added and the mixture is reacted for 30-60 minutes at the same temperature and stirring rate; (2) Mixing reaction: adding silica sol and borax in sequence, stirring each time for 15-30 min at the same temperature and stirring rate as in step (1); adding triethanolamine solution, and reacting at 60-70° C. and maintaining the same stirring rate for 20-40 min; (3) Adding auxiliary agents: After the reaction in step (2) is completed, add a pH adjuster, a thickener, a dispersant and a complexing agent, and heat and stir for 5-10 minutes after each raw material is added to finally generate a water-containing solid; (4) Post-treatment: The generated water-containing solid is dried with a drying device. After drying, the grinding device is turned on for grinding to obtain the accelerator masterbatch powder, which is packaged and stored to obtain a low-alkali, chlorine-free powdery soluble accelerator masterbatch finished product.

7. The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent according to claim 6, characterized in that: In step (1), the stirring rate is 500-600 r / min, and the reaction kettle is heated to 40-60° C.

8. The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent according to claim 6, characterized in that: The heating in step (3) is to heat the mixture to 75-80°C.

9. The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent according to claim 6, characterized in that: The stirring rate of step (3) is 200-300 r / min.

10. The preparation process of the low-alkali chlorine-free powdered masterbatch soluble quick-setting agent according to claim 6, characterized in that: In step (4), the grinding accuracy of the grinding device is set to a particle size of 80-200 mesh.

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