Elasticity reducer for sprayed concrete and preparation method thereof
By preparing a shotcrete reducer containing active aluminum, activator, setting regulator, and pH regulator components, the problems of slow setting and large rebound of shotcrete were solved, achieving early strength improvement and construction safety, and ensuring the smooth progress of construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-04-10
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Abstract
Description
Technical Field
[0001] This invention relates to the field of road construction materials, and more specifically, to a shotcrete reducer and its preparation method. Background Technology
[0002] Shotcrete is a type of concrete that is rapidly hardened after being sprayed at high speed onto a target surface using spraying equipment. It is widely used in tunnel engineering, water conservancy projects, coal mine construction, mine restoration, and slope protection. Tunnel environments are complex, with some areas having poor surrounding rock quality and severe water seepage. Furthermore, some projects are located in high-altitude, cold regions with low construction temperatures. These factors result in slow setting time and incomplete cement hydration of shotcrete during construction. This makes the shotcrete prone to falling off the rock strata, exhibiting significant rebound, and lacking sufficient strength within the first few hours after application, leading to poor support effectiveness and substantial safety hazards.
[0003] Traditional shotcrete reducers are broadly classified into liquid and solid types. Their main mechanisms are: improving the workability of shotcrete, increasing its cohesiveness, encapsulation, and workability to achieve shotcrete reduction; and introducing some fast-setting materials to accelerate the setting of shotcrete, thereby achieving shotcrete reduction.
[0004] However, improving the workability of concrete to reduce its elasticity can easily lead to excessive viscosity of the shotcrete if the dosage is not carefully controlled, resulting in loss of fluidity and construction difficulties. Introducing some fast-setting materials can cause these materials to solidify during the transportation of the shotcrete, rendering it unusable on the construction site. Summary of the Invention
[0005] The purpose of this invention is to provide a shotcrete elasticity reducer and its preparation method. By adding an active aluminum-containing component, an activating component, a setting regulating component, a pH regulating component, and a state regulating component, the shotcrete elasticity reducer can shorten the setting time of shotcrete, reduce the rebound of shotcrete, and generate a large amount of AFt, thereby promoting the early strength improvement of shotcrete.
[0006] The technical problem solved by this invention is achieved by the following technical solution.
[0007] On one hand, embodiments of this application provide a method for preparing a shotcrete elasticity reducer, comprising the following steps: S1: By mass fraction, select 300-400 parts of aluminum source, 200-300 parts of sodium hydroxide, and 400-500 parts of deionized water. Mix and react at 100-130℃ for 2-3 hours. After the reaction is complete, introduce carbon dioxide to obtain a precipitate. Then filter and dry the precipitate to obtain the active aluminum-containing component. S2: Select 10-30 parts kerosene and 0.1-0.5 parts Span-80 as the oil phase, and a mixed solution of 25-35 parts calcium nitrate, 5-15 parts alkaline silica sol and 50-100 parts deionized water as the aqueous phase. Under ultrasonic conditions, first centrifuge and disperse the oil phase, add the aqueous phase dropwise during the dispersion process, and continuously purge carbon dioxide. Stop the reaction when the pH of the solution is neutral, and wash and dry the obtained product to obtain the activation component. S3: Select 20-50 parts of activating component, 100-300 parts of active aluminum-containing component, 600-820 parts of setting regulating component, 5-10 parts of pH regulating component and 20-50 parts of state regulating component, mix and grind for 30-80 minutes to obtain shotcrete reducer.
[0008] Furthermore, in step S1, the aluminum source is aluminum hydroxide and / or boehmite.
[0009] Furthermore, in step S2, dichloromethane is used for washing, and the drying temperature is 60°C.
[0010] Furthermore, in step S3, the setting regulating component is any one or more of hemihydrate gypsum, dihydrate gypsum, and anhydrite.
[0011] Furthermore, the pH adjusting component is any one or more of sodium silicate, sodium hydroxide, and tetramethylammonium hydroxide.
[0012] Furthermore, the state-conditioning component is any one or more of sodium polyacrylate, polyacrylamide, and cellulosic hydrolysate.
[0013] On the other hand, embodiments of the present invention provide a shotcrete de-elasticity agent, which is prepared by the above method.
[0014] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. The elasticity reducer prepared in this invention, by adding an active aluminum-containing component, can react with H in the quick-setting agent. + With F - The reaction generates soluble fluoroaluminate complexes, increasing the soluble aluminum ion content in shotcrete, thus shortening the setting time of shotcrete. 2. By adding setting regulator components, this invention not only adjusts the setting time of concrete, but also replenishes the sulfate ions missing in the system, resulting in the generation of a large amount of AFt in the shotcrete and promoting the improvement of early strength of concrete. 3. This invention, by adding state-adjusting and pH-adjusting components, can both increase the workability of concrete and prevent bleeding, segregation, or insufficient slump; and ensure that the shotcrete is always in an alkaline system, providing sufficient OH-. -This helps dissolve C3S, providing conditions for the development of early strength in concrete. Detailed Implementation
[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.
[0017] Example 1 This embodiment provides a shotcrete reducer, which is prepared by the following method: S1: By mass fraction, select 340 parts of aluminum source, 250 parts of sodium hydroxide, and 410 parts of deionized water. Mix and react at 110℃ for 2 hours. After the reaction is complete, carbon dioxide is introduced to obtain a precipitate of active aluminum-containing component. Then, filter the precipitate with a filter press to obtain an active aluminum-containing component with a water content of 85%. Then, dry the active aluminum-containing component with a water content of 85% at a temperature not higher than 260℃ to obtain the dry active aluminum-containing component. S2: Select 20 parts kerosene and 0.3 parts Span-80 as the oil phase, and a mixed solution of 30 parts calcium nitrate, 10 parts alkaline silica sol and 70 parts deionized water as the aqueous phase. Under ultrasonic conditions of 35-40 kHz, first add the oil phase to the beaker, then centrifuge at 3000 rpm to disperse it. During the dispersion process, slowly add the aqueous phase dropwise and continuously pass carbon dioxide. Stop the reaction when the pH of the mixed solution of aqueous and oil phases is neutral. Wash the obtained product with dichloromethane to remove excess kerosene, and then dry the product at 60℃. After drying, the activated component (i.e., silica sol-doped nano-calcium carbonate) can be obtained. S3: Select 20 parts of activating component, 300 parts of active aluminum-containing component, 620 parts of setting adjustment component, 10 parts of pH adjustment component and 50 parts of state adjustment component, put them into a ball mill, mix and grind for 30 minutes to obtain a powder product with a mesh size of 300, which is the shotcrete reducer.
[0018] The coagulation regulating component is gypsum dihydrate, the pH regulating component is tetramethylammonium hydroxide, and the state regulating component is cellulose enzymatic hydrolysis product.
[0019] It should be noted that in this embodiment, the active aluminum-containing component has low solubility in the concrete system and has limited effect on shortening the concrete setting time. However, when this component encounters a fluoride-containing accelerator, it will be dissolved by the fluoride ions to form a large amount of aluminum fluoride complex, which increases the solubility of aluminum ions in the system. Excess aluminum ions react with sulfate and calcium ions in the system to form more AFm and AFt, thereby causing the concrete to set rapidly.
[0020] In addition, in the early stage of cement hydration, due to the high concentration of free ions in cement, the hydration products have a strong initial crystal nucleation barrier to overcome during crystallization, so it takes a long time to form crystals; while the excitation component has a small particle size, a high specific surface area, and can act as a crystal nucleus to induce the rapid generation of hydration products, laying a good foundation for the subsequent formation of AFt.
[0021] Furthermore, gypsum, a common setting regulator in cement, forms a small amount of AFt with a small amount of dissolved aluminum ions. These AFt particles coat the active sites on the surfaces of cement particles and active aluminum-containing components, preventing further reaction between the cement and the active aluminum-containing components. Due to the introduction of active aluminum-containing components, a large amount of AFm and AFt are formed in the system, resulting in an excess of gypsum. Some unreacted gypsum slowly dissolves and reacts with AFm to generate AFt, thus achieving an early strength effect.
[0022] Example 2 The steps in this embodiment are basically the same as those in Embodiment 1, except that in step S3, the mixture is ground for 45 minutes to obtain a powdered product with a mesh size of 400, which is the shotcrete reducer.
[0023] Example 3 The steps in this embodiment are basically the same as those in Embodiment 1, except that in step S3, the mixture is ground for 60 minutes to obtain a powdered product with a mesh size of 450, which is the shotcrete reducer.
[0024] Example 4 The steps in this embodiment are basically the same as those in Embodiment 1, except that in step S3, the mixture is ground for 80 minutes to obtain a powdered product with a mesh size of 500, which is the shotcrete reducer.
[0025] Example 5 The steps in this embodiment are basically the same as those in Embodiment 1, except that in step S3, 20 parts of activating component, 225 parts of active aluminum-containing component, 695 parts of setting adjustment component, 10 parts of pH adjustment component and 50 parts of state adjustment component are selected, put into a ball mill, mixed and ground for 30 minutes to obtain a powdered product with a mesh size of 300, which is the shotcrete reducer.
[0026] Example 6 The steps in this embodiment are basically the same as those in embodiment 5, except that in step S3, 20 parts of the activating component, 150 parts of the active aluminum-containing component, 770 parts of the coagulation regulating component, 10 parts of the pH regulating component and 50 parts of the state regulating component are selected.
[0027] Example 7 The steps in this embodiment are basically the same as those in embodiment 5, except that in step S3, 20 parts of the activating component, 100 parts of the active aluminum-containing component, 820 parts of the coagulation regulating component, 10 parts of the pH regulating component and 50 parts of the state regulating component are selected.
[0028] Example 8 The steps in this embodiment are basically the same as those in Embodiment 5, except that in step S3, 35 parts of the activating component, 300 parts of the active aluminum-containing component, 620 parts of the coagulation regulating component, 10 parts of the pH regulating component and 50 parts of the state regulating component are selected.
[0029] Example 9 The steps in this embodiment are basically the same as those in embodiment 8, except that in step S3, 50 parts of the activating component, 300 parts of the active aluminum-containing component, 620 parts of the coagulation regulating component, 10 parts of the pH regulating component and 50 parts of the state regulating component are selected.
[0030] Example 10 The steps in this embodiment are basically the same as those in embodiment 8, except that in step S3, 20 parts of the activating component, 300 parts of the active aluminum-containing component, 620 parts of the coagulation regulating component, 5 parts of the pH regulating component and 50 parts of the state regulating component are selected.
[0031] Example 11 The steps in this embodiment are basically the same as those in Embodiment 10, except that in step S3, 20 parts of the activating component, 300 parts of the active aluminum-containing component, 620 parts of the coagulation regulating component, 5 parts of the pH regulating component and 35 parts of the state regulating component are selected.
[0032] Example 12 The steps in this embodiment are basically the same as those in Embodiment 10, except that in step S3, 20 parts of the activating component, 300 parts of the active aluminum-containing component, 620 parts of the coagulation regulating component, 5 parts of the pH regulating component and 20 parts of the state regulating component are selected.
[0033] Comparative Example 1 The steps of this comparative example and Example 1 are basically the same, except that in step S3, 20 parts of the activating component, 900 parts of the active aluminum-containing component, 10 parts of the pH adjustment component and 20 parts of the state adjustment component are selected.
[0034] Comparative Example 2 The steps of this comparative example and Example 1 are basically the same, except that in step S3, 20 parts of the activation component, 620 parts of the coagulation adjustment component, 10 parts of the pH adjustment component and 20 parts of the state adjustment component are selected.
[0035] Comparative Example 3 The steps of this comparative example and Example 1 are basically the same, except that in step S3, 300 parts of active aluminum-containing component, 620 parts of coagulation regulating component, 10 parts of pH regulating component and 20 parts of state regulating component are selected.
[0036] Comparative Example 4 The steps of this comparative example and Example 1 are basically the same, except that in step S3, 920 parts of ordinary cement, 10 parts of pH adjustment component and 20 parts of state adjustment component are selected.
[0037] The performance of the elasticity-reducing agents prepared in Examples 1 to 4 was then tested. The setting time of the neat cement paste with and without the elasticity-reducing agent was tested according to GB 175-2023 "General Portland Cement". The setting time and compressive strength of the mortar at 3 hours, 8 hours, and 1 day were tested according to GB / T35159-2017 "Accelerators for Shotcrete". The test results are shown in Tables 1 and 2. Table 1. Setting time without accelerators
[0038] Table 2. Time and compressive strength after adding accelerator
[0039] By combining Table 1 and Table 2, we can conclude that: From the blank group, Example 1, and Comparative Example 1, it can be seen that without adding setting regulator, Comparative Example 1 has the fastest setting time after adding accelerator, but its strength is very low at 3h, 8h, and 1d. This is because Comparative Example 1 contains only a large amount of active aluminum component, which can significantly shorten the setting time. However, due to the lack of sulfate ion replenishment from the setting regulator, the slurry only generates more AFm rather than the higher-strength AFt.
[0040] Comparative Example 2, Example 1 and the blank group show that without the addition of active aluminum component, the setting time is significantly prolonged. After adding the accelerator, the setting time does not meet the requirements of GB / T 35159-2017 "Accelerator for Shotcrete". Furthermore, the mortar does not set for a long time, resulting in no compressive strength at 3h and 8h and low strength at 1d.
[0041] Comparative Example 3, Example 1, Comparative Example 4, and the blank group show that without the addition of the activating component, the elasticity reducer can still shorten the setting time of the neat paste, but it does not significantly improve the early strength. Using only the activating component has no effect on either the setting time or the early strength of the neat paste.
[0042] As seen in Examples 1, 2, 3, and 4, a larger mesh size results in faster setting, significantly shortening the setting time of the paste even without an accelerator. However, it has no significant impact on compressive strength.
[0043] As seen in Examples 5, 6, and 7, reducing the amount of active aluminum component resulted in a longer solidification time and a slight decrease in compressive strength.
[0044] As can be seen from Examples 8 and 9, increasing the amount of activator can significantly improve the early compressive strength, but has no significant effect on improving the setting time.
[0045] Comparing Example 10, Example 1, and the blank group, it can be seen that reducing the pH adjuster has no significant effect on the setting time, but weakens the effect on improving the compressive strength of the mortar.
[0046] Comparing Examples 11 and 12 with Example 1, changing the amount of concrete conditioner had no significant effect on the setting time of the cement paste and the compressive strength of the mortar.
[0047] In summary, the present invention provides a method for preparing a shotcrete elasticity reducer, which, by adding an active aluminum-containing component, can react with H+ and F- in the quick-setting agent to generate a soluble fluoroaluminum complex, thereby increasing the soluble aluminum ion content in the shotcrete and thus shortening the setting time of the shotcrete. This invention, by adding setting regulator components, not only adjusts the setting time of concrete but also replenishes the missing sulfate ions in the system, resulting in the generation of a large amount of AFt in the shotcrete and promoting the improvement of early strength of concrete. This invention, by adding state-adjusting and pH-adjusting components, can increase the workability of concrete and prevent bleeding, segregation, or insufficient slump. It can also ensure that the shotcrete is always in an alkaline system, providing sufficient OH- to facilitate the dissolution of C3S and provide conditions for the early strength development of concrete.
[0048] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
1. A method for preparing a shotcrete de-elasticity agent, characterized in that, Includes the following steps: S1: By mass fraction, select 300-400 parts of aluminum source, 200-300 parts of sodium hydroxide, and 400-500 parts of deionized water. Mix and react at 100-130℃ for 2-3 hours. After the reaction is complete, introduce carbon dioxide to obtain a precipitate. Then filter and dry the precipitate to obtain the active aluminum-containing component. S2: Select 10-30 parts kerosene and 0.1-0.5 parts Span-80 as the oil phase, and a mixed solution of 25-35 parts calcium nitrate, 5-15 parts alkaline silica sol and 50-100 parts deionized water as the aqueous phase. Under ultrasonic conditions, first centrifuge and disperse the oil phase, add the aqueous phase dropwise during the dispersion process, and continuously purge carbon dioxide. Stop the reaction when the pH of the solution is neutral, and wash and dry the obtained product to obtain the activation component. S3: Select 20-50 parts of activating component, 100-300 parts of active aluminum-containing component, 600-820 parts of setting regulating component, 5-10 parts of pH regulating component and 20-50 parts of state regulating component, mix and grind for 30-80 minutes to obtain shotcrete reducer.
2. The method for preparing a shotcrete de-elasticity agent according to claim 1, characterized in that, In step S1, the aluminum source is aluminum hydroxide and / or boehmite.
3. The method for preparing a shotcrete de-elasticity agent according to claim 1, characterized in that, In step S2, dichloromethane is used for washing, and the drying temperature is 60°C.
4. The method for preparing a shotcrete de-elasticity agent according to claim 1, characterized in that, In step S3, the setting regulating component is any one or more of hemihydrate gypsum, dihydrate gypsum, and anhydrite.
5. The method for preparing a shotcrete de-elasticity agent according to claim 4, characterized in that, The pH adjusting component is any one or more of sodium silicate, sodium hydroxide, and tetramethylammonium hydroxide.
6. The method for preparing a shotcrete de-elasticity agent according to claim 5, characterized in that, The state-conditioning component is any one or more of sodium polyacrylate, polyacrylamide, and cellulosic hydrolysate.
7. A shotcrete elasticity reducer, characterized in that, It is prepared by the method for preparing a shotcrete reducer as described in any one of claims 1-6.