An air entraining agent for roller compacted concrete and a method for preparing the same

Abstract

The application discloses a kind of air entraining agent for roller compacted concrete and a preparation method thereof, which is prepared by compounding air entraining component A, gas stabilizing and enhancing component B and sensitivity reducing component C in a weight ratio of (450-550):(250-350):(100-300). Air entraining component A is prepared by esterification and quaternary ammonium reaction of modified rosin. Gas stabilizing and enhancing component B is prepared by dispersing nano-silicon dioxide. Sensitivity reducing component C is a multi-surfactant compound system. Through the synergistic effect of the three components, the application solves the problems of poor air entraining effect, easy bubble breakage and sensitivity of air content to VC value of conventional air entraining agents in roller compacted concrete. The application can significantly improve the frost resistance and impermeability of concrete, ensure early and later compressive strength, and is suitable for water conservancy dam construction in high-altitude and severe cold regions, and has good practicality and promotional value.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures, and in particular to an air-entraining agent for roller-compacted concrete and its preparation method. Background Technology

[0002] Roller-compacted concrete (RCC) is a dry-hard, zero-slump concrete that is compacted through methods similar to road construction, such as paving and rolling. It not only possesses the strength and durability of traditional concrete but also exhibits high impermeability and low shrinkage. Furthermore, it boasts advantages in construction technology, including high mechanization, simple construction, fast construction speed, and low cost. As a result, it is widely used in dam structures in water conservancy projects, and its unique advantages have played a significant role in the development of dam construction technology.

[0003] However, many hydraulic engineering projects are located in high-altitude, frigid regions, where concrete is exposed to harsh environments such as low air pressure, large temperature differences, and strong radiation for extended periods, making it highly susceptible to freeze-thaw cycles. To improve frost resistance, air-entraining agents are typically added to concrete to introduce a large number of independent, closed, tiny, and uniformly distributed air bubbles, thereby alleviating frost heave stress. However, due to the small volume and high viscosity of roller-compacted concrete, conventional air-entraining agents are less effective at entraining air in its system. More seriously, during the vibratory compaction process, the intense compaction action can destroy the already formed bubble structure, causing bubbles to merge, rupture, or escape, ultimately resulting in a significant decrease in the frost resistance and impermeability of roller-compacted concrete, affecting its normal use in hydraulic structures.

[0004] Furthermore, the air-entraining effect of existing air-entraining agents is extremely sensitive to the workability of roller-compacted concrete mixtures (usually characterized by VC value). Even slight fluctuations in VC value can cause the air content of concrete to deviate significantly from the design range, increasing the difficulty of quality control and engineering risks, thus hindering the widespread application of roller-compacted concrete in water conservancy projects in frigid regions.

[0005] Therefore, developing a novel air-entraining agent that can effectively improve the frost resistance and impermeability of roller-compacted concrete, while being insensitive to changes in VC value and exhibiting high air-entraining stability, is of great practical significance and application value for ensuring the durability and reliability of roller-compacted concrete in high-altitude and cold-weather water conservancy dam projects. Summary of the Invention

[0006] The purpose of this invention is to provide an air-entraining agent for roller-compacted concrete and its preparation method, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: This invention provides an air-entraining agent for roller-compacted concrete, the raw materials of which include the following raw material components in parts by weight: Gas-entraining component A: 450-550 parts; Gas-stabilizing and enhancing component B: 250-350 parts; Sensitivity-reducing component C: 100-300 parts; The preparation method of the air-entraining component A includes the following steps: (1) Esterification reaction of fuma-modified rosin with 3-chloro-1,2-epoxypropane to obtain an intermediate; (2) The intermediate is subjected to a quaternization reaction with a binary aliphatic tertiary amine to obtain the air-entraining component A; The preparation method of the gas-stabilizing and enhancing component B includes the following steps: adding a suspension stabilizer dropwise to a mixture of nano-silica and silane coupling agent to obtain the gas-stabilizing and enhancing component B; The desensitizing component C is composed of the following components in the following weight ratio: anionic surfactant: fluorocarbon surfactant: sodium polyacrylate: silicone defoamer: deionized water = (1-3): (1-3): (2-4): (0.5-1.5): 95; The suspension stabilizer consists of xanthan gum, hydroxypropyl methylcellulose and deionized water.

[0008] Furthermore, the esterification reaction is carried out at a temperature of 70-80℃ for a time of 60-120 min; the quaternization reaction is carried out at a temperature of 75-85℃ for a time of 60-120 min.

[0009] Further, the binary aliphatic tertiary amine is N,N,N',N'-tetramethyl-1,6-hexanediamine; the weight ratio of the fumarate-modified rosin to 3-chloro-1,2-epoxypropane is (120-180):(30-40); the weight ratio of the intermediate to N,N,N',N'-tetramethyl-1,6-hexanediamine is (45-55):(15-25).

[0010] Furthermore, the acid value of the fuma-modified rosin is not less than 210 mg KOH / g.

[0011] Furthermore, the preparation method of the fuma-modified rosin includes the following steps: rosin and fumaric acid are subjected to an addition reaction at 200°C to obtain fuma-modified rosin; the reaction time is preferably 4 hours; the preferred reaction mass ratio is rosin:fumaric acid = 500:120.

[0012] Furthermore, the weight ratio of the nano-silica, silane coupling agent, xanthan gum, hydroxypropyl methylcellulose and deionized water is (15-25):(3-5):(0.5-1.5):(0.5-1.5):500.

[0013] Furthermore, the xanthan gum has a viscosity of 150,000-200,000, and the hydroxypropyl methylcellulose has a viscosity of 150,000-200,000.

[0014] Furthermore, a phase transfer catalyst is added to the esterification reaction system in step (1); preferably hexadecyltrimethylammonium bromide.

[0015] Further, the weight ratio of hexadecyltrimethylammonium bromide to the fuma-modified rosin is (2-4):(120-180).

[0016] The present invention also provides a method for preparing the above-mentioned air-entraining agent for roller-compacted concrete, comprising the following steps: The air-entraining component A, the air-stabilizing and reinforcing component B, and the sensitivity-reducing component C are mixed to obtain the air-entraining agent for roller-compacted concrete.

[0017] The present invention further provides the application of the above-mentioned air-entraining agent for roller-compacted concrete in roller-compacted concrete.

[0018] This invention relates to a low-sensitivity air-entraining agent for roller-compacted concrete. Through the synergistic effect of air-entraining component A, air-stabilizing and reinforcing component B, and sensitivity-reducing component C, it achieves an integrated function of high-efficiency air entrainment, bubble stabilization, and low VC value sensitivity. Air-entraining component A is prepared from modified rosin as a base material through a two-step modification reaction: first, the modified rosin undergoes an esterification reaction with 3-chloro-1,2-epoxypropane, and then undergoes a quaternization reaction with N,N,N',N'-tetramethyl-1,6-hexanediamine. The molecular structure of this component retains the rosin tri-phenanthroline ring, giving the molecule high rigidity and making it less prone to distortion, thus ensuring the stability of the formed bubble film structure. Simultaneously, the modified molecule possesses the characteristics of a geminal quaternary ammonium salt-type air-entraining agent, effectively reducing the critical micelle concentration. Even in systems with low volume and high viscosity of roller-compacted concrete paste, it can efficiently generate a large number of tiny, independent, and uniformly distributed closed air bubbles. These bubbles provide a buffer space for the freezing and migration of free water in the cement paste, releasing the internal pressure generated by freeze-thaw cycles, fundamentally preventing cracking and spalling of concrete due to freeze-thaw cycles, and significantly improving the freeze-thaw resistance of concrete.

[0019] The gas-stabilizing and reinforcing component B achieves both gas stabilization and reinforcement through physical dispersion: On the one hand, the nano-silica particles in the component can be adsorbed onto the surface of air bubbles, increasing the surface roughness of the bubbles and enhancing their frictional resistance in the slurry, thereby reducing bubble migration and aggregation, preventing them from breaking and escaping during compaction, and further strengthening bubble stability; on the other hand, nano-silica can act as anchoring points for the hydration reaction in the early stages of cement hydration, promoting the formation of more CSH gel and ettringite, optimizing the microstructure of concrete, and thus improving the early and later compressive strength of concrete. Furthermore, nano-silica can also isolate and disperse the molecules of air-entraining component A, promoting the formation of smaller micelles, further enhancing the foaming ability of air-entraining component A.

[0020] The desensitization component C achieves the core objective of low sensitivity of air-entraining effect to VC value through the synergistic effect of multiple components. Among them, the anionic surfactant and fluorocarbon surfactant, after being compounded, can synergistically arrange with the air-entraining component A molecules to form a more compact and ordered micellar structure, enabling air-entraining component A to generate bubbles quickly and efficiently even under conditions of less stirring work; while sodium polyacrylate, as a key functional component, plays a thickening and water-locking role, which can adjust the viscosity of the slurry and balance the moisture distribution of the slurry under different VC values. This ensures that even if the VC value of the roller-compacted concrete mixture fluctuates slightly, the air-entraining agent can still stably produce the target air content, significantly reducing the sensitivity of air content to VC value and improving the convenience and accuracy of quality control in the mixing plant.

[0021] The present invention discloses the following technical effects: This invention provides an air-entraining agent suitable for roller-compacted concrete, which significantly improves the freeze-thaw resistance and impermeability of roller-compacted concrete in harsh environments such as extreme cold and high altitude.

[0022] This invention's air-entraining agent, through optimized molecular structure and compounding system, can stably introduce a large number of tiny, closed, and uniformly distributed air bubbles into dry, hard roller-compacted concrete with low slurry volume and high viscosity. This effectively alleviates the internal stress generated by freeze-thaw cycles. Simultaneously, the formed bubble structure exhibits excellent compressive stability, making it less prone to rupture, coalescence, or escape during vibratory compaction, thus ensuring that the air content of the finished concrete meets design requirements. Crucially, this invention's air-entraining agent significantly reduces the sensitivity of the workability (VC value) of the roller-compacted concrete mixture. Even with fluctuations in VC value, it maintains stable air content, greatly improving the quality controllability and consistency during construction.

[0023] This invention not only overcomes the technical bottlenecks of low air entrainment efficiency and poor stability of traditional air-entraining agents in roller-compacted concrete, but also provides reliable material support for the construction of high-durability hydraulic dams, and has good engineering application prospects and promotion value. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0030] This invention provides a low-sensitivity air-entraining agent for roller-compacted concrete, comprising air-entraining component A, air-stabilizing and reinforcing component B, and low-sensitivity component C in specific weight parts. The weight ratio of each component is: air-entraining component A 450-550 parts, air-stabilizing and reinforcing component B 250-350 parts, and low-sensitivity component C 100-300 parts. A preferred preparation process is as follows: I. Preparation of entraining component A: Weigh 120-180 parts by weight of fumaric modified rosin, grind it into powder, and mix it evenly with 2-4 parts by weight of hexadecyltrimethylammonium bromide. Add the mixture to a reactor equipped with a stirrer, a dropping device, a heating device, and a reflux device, and then add 400-500 parts by weight of isopropanol. Set the initial temperature of the reactor to 70-80℃ and the stirring speed to 280-350 r / min. Stir until the raw materials are completely dissolved, then add 30-40 parts by weight of 3-chloro-1,2-epoxypropane dropwise, controlling the dropping time to 1-2 h. After the dropping is completed, continue the reaction for 60-120 min to obtain a light yellow transparent liquid. Then connect a reflux condenser and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted 3-chloro-1,2-epoxypropane and isopropanol to obtain a light yellow solid A1.

[0031] In a separate reactor equipped with a stirrer, dropping device, heating, and reflux device, weigh 45-55 parts of the above solid Al and dissolve it in 180-220 parts of isopropanol. Set the initial temperature to 75-85℃ and the stirring speed to 280-350 r / min. After stirring until Al is completely dissolved, add 15-25 parts of N,N,N',N'-tetramethyl-1,6-hexanediamine dropwise over a period of 1-2 hours. After the addition is complete, continue the reaction for 60-120 minutes. Connect the reflux condenser again and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted N,N,N',N'-tetramethyl-1,6-hexanediamine and isopropanol, finally obtaining the yellow entraining component A.

[0032] II. Preparation of Gas Stabilizing and Enhancing Component B Take a reactor equipped with a high-speed stirrer and a dropping device, add 15-25 parts of nano-silica and 3-5 parts of silane coupling agent, set the stirring speed to 1500-2500 r / min, and then dropwise add a suspension stabilizer (composed of 0.5-1.5 parts of xanthan gum with a viscosity of 200,000, 0.5-1.5 parts of hydroxypropyl methylcellulose with a viscosity of 200,000, and 500 parts of deionized water), controlling the dropping time to 1 h; after the dropping is completed, continue stirring for 1 h to obtain a solution of gas-stabilizing and reinforcing component B.

[0033] III. Preparation of Desensitizing Component C Mix 1-3 parts of anionic surfactant, 1-3 parts of fluorocarbon surfactant, 2-4 parts of sodium polyacrylate, 0.5-1.5 parts of silicone defoamer with 95 parts of deionized water to obtain desensitizing component C.

[0034] IV. Compound Weigh the prepared air-entraining component A, air-stabilizing and reinforcing component B, and desensitizing component C according to the above weight ratio, and mix the three evenly to obtain the low-sensitivity air-entraining agent for roller-compacted concrete described in this invention.

[0035] Furthermore, the acid value of the fuma-modified rosin is not less than 210 mg KOH / g.

[0036] Furthermore, the preparation method of the fuma-modified rosin includes the following steps: rosin and fumaric acid are subjected to an addition reaction at 200°C to obtain fuma-modified rosin; the reaction time is preferably 4 hours; the preferred reaction mass ratio is rosin:fumaric acid = 500:120.

[0037] In this embodiment of the invention, commercially available fuma modified rosin is used.

[0038] The present invention will be further described in detail below with reference to embodiments: Example 1 This embodiment provides a low-sensitivity air-entraining agent for roller-compacted concrete, with the following raw material weight proportions: Gas-entraining component A: 450 parts; Gas-stabilizing and enhancing component B: 250 parts; Sensitivity-reducing component C: 300 parts; The preparation steps are as follows: (1) Preparation of air-entraining component A: Weigh 120 parts of fuma-modified rosin (FR-107 model, Guangxi Wuzhou Richeng Forestry Chemical Co., Ltd.), grind it into powder, and mix it evenly with 2 parts of hexadecyltrimethylammonium bromide. Add the mixture to a reactor equipped with a stirrer, dropping device, heating device, and reflux device. Then add 400 parts of isopropanol to the reactor. Set the initial reactor temperature to 70℃ and the stirring speed to 280 r / min. After stirring until the raw materials are completely dissolved, add 30 parts of 3-chloro-1,2-epoxypropane dropwise to the reactor over a time of 1 hour. After the addition is complete, continue the reaction for 60 minutes to obtain a light yellow transparent liquid. Then connect a reflux condenser and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted 3-chloro-1,2-epoxypropane and isopropanol, obtaining a light yellow solid A1. In a separate reactor equipped with a stirrer, a dropping device, a heating device, and a reflux device, 45 parts of the solid Al prepared above were weighed and dissolved in 180 parts of isopropanol. The initial temperature of the reactor was set to 75℃ and the stirring speed to 280 r / min. After stirring until Al was completely dissolved, 15 parts of N,N,N',N'-tetramethyl-1,6-hexanediamine were added dropwise to the reactor over a time of 1 hour. After the addition was complete, the reaction was continued for 60 minutes. A reflux condenser was then connected again, and unreacted N,N,N',N'-tetramethyl-1,6-hexanediamine and isopropanol were evaporated using a rotary evaporator at 50 kPa and 60℃, finally yielding a yellow entraining component A.

[0039] (2) Preparation of gas-stabilizing and enhancing component B: Take a reactor equipped with a high-speed stirrer and a dropping device, add 15 parts of nano-silica (Evonik Industries A200 model) and 3 parts of silane coupling agent (Shandong Huachen New Material Co., Ltd. KH-560 model), set the stirring speed to 1500 r / min, and then start adding a suspension stabilizer (which consists of 0.5 parts of xanthan gum with a viscosity of 200,000, 0.5 parts of hydroxypropyl methylcellulose with a viscosity of 200,000 and 500 parts of deionized water), and control the dropping time to 1 hour; after the dropping is completed, continue stirring for 1 hour to obtain a solution of gas-stabilizing and reinforcing component B.

[0040] (3) Preparation of desensitizing component C: One part of anionic surfactant (TEGO XP 22076 from Evonik Industries), one part of fluorocarbon surfactant (YM-3016 from Shanghai Yumu Chemical Co., Ltd.), two parts of sodium polyacrylate (average molecular weight 4 million to 5 million; 9003-04-7 from Shanghai Maclean Biochemical Technology Co., Ltd.), and 0.5 parts of silicone defoamer (XPJ-YJG 40% silicone defoamer from Qingzhou Xuanlang Industry and Trade Co., Ltd.) were mixed evenly with 95 parts of deionized water to obtain the desensitizing component C.

[0041] (4) Compound preparation: Weigh out the prepared air-entraining component A, air-stabilizing and reinforcing component B, and desensitizing component C according to the above-mentioned weight proportions, and mix the three evenly to obtain the low-sensitivity air-entraining agent for roller-compacted concrete in this embodiment.

[0042] Example 2 This embodiment provides a low-sensitivity air-entraining agent for roller-compacted concrete, with the following raw material weight proportions: Gas-entraining component A: 550 parts; Gas-stabilizing and enhancing component B: 350 parts; Sensitivity-reducing component C: 100 parts; The preparation steps are as follows: (1) Preparation of air-entraining component A: Weigh 180 parts of fuma-modified rosin (FR-107 model, Guangxi Wuzhou Richeng Forestry Chemical Co., Ltd.), grind it into powder, and mix it evenly with 4 parts of hexadecyltrimethylammonium bromide. Add the mixture to a reactor equipped with a stirrer, dropping device, heating device, and reflux device. Then add 500 parts of isopropanol to the reactor. Set the initial reactor temperature to 80℃ and the stirring speed to 350 r / min. After stirring until the raw materials are completely dissolved, add 40 parts of 3-chloro-1,2-epoxypropane dropwise to the reactor over a time of 2 hours. After the addition is complete, continue the reaction for 120 minutes to obtain a light yellow transparent liquid. Then connect a reflux condenser and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted 3-chloro-1,2-epoxypropane and isopropanol, obtaining a light yellow solid A1. In a separate reactor equipped with a stirrer, a dropping device, a heating device, and a reflux device, 55 parts of the solid Al prepared above were weighed and dissolved in 220 parts of isopropanol. The initial temperature of the reactor was set to 85℃ and the stirring speed to 350 r / min. After stirring until Al was completely dissolved, 25 parts of N,N,N',N'-tetramethyl-1,6-hexanediamine were added dropwise to the reactor over a period of 2 hours. After the addition was complete, the reaction was continued for 120 minutes. A reflux condenser was then connected again, and unreacted N,N,N',N'-tetramethyl-1,6-hexanediamine and isopropanol were evaporated using a rotary evaporator at 50 kPa and 60℃, finally yielding a yellow entraining component A.

[0043] (2) Preparation of gas-stabilizing and enhancing component B: Take a reactor equipped with a high-speed stirrer and a dropping device, add 25 parts of nano-silica (Evonik Industries A200 model) and 5 parts of silane coupling agent (Shandong Huachen New Materials Co., Ltd. KH-560 model), set the stirring speed to 2500 r / min, and then start adding a suspension stabilizer (which consists of 1.5 parts of xanthan gum with a viscosity of 200,000, 1.5 parts of hydroxypropyl methylcellulose with a viscosity of 200,000 and 500 parts of deionized water), and control the dropping time to 1 hour; after the dropping is completed, continue stirring for 1 hour to obtain a solution of gas-stabilizing and reinforcing component B.

[0044] (3) Preparation of desensitizing component C: Three parts of anionic surfactant (TEGO XP 22076 from Evonik Industries), three parts of fluorocarbon surfactant (YM-3016 from Shanghai Yumu Chemical Co., Ltd.), four parts of sodium polyacrylate (average molecular weight 4 million to 5 million; 9003-04-7 from Shanghai Maclean Biochemical Technology Co., Ltd.), and one and a half parts of silicone defoamer (XPJ-YJG 40% silicone defoamer from Qingzhou Xuanlang Industry and Trade Co., Ltd.) were mixed evenly with 95 parts of deionized water to obtain the desensitizing component C.

[0045] (4) Compound preparation: Weigh out the prepared air-entraining component A, air-stabilizing and reinforcing component B, and desensitizing component C according to the above-mentioned weight proportions, and mix the three evenly to obtain the low-sensitivity air-entraining agent for roller-compacted concrete in this embodiment.

[0046] Example 3 This embodiment provides a low-sensitivity air-entraining agent for roller-compacted concrete, with the following raw material weight proportions: Gas-entraining component A 500 parts, gas-stabilizing and enhancing component B 300 parts, and sensitivity-reducing component C 200 parts; The preparation steps are as follows: (1) Preparation of air-entraining component A: Weigh 150 parts of fuma-modified rosin (FR-107 model, Guangxi Wuzhou Richeng Forestry Chemical Co., Ltd.), grind it into powder, and mix it evenly with 3 parts of hexadecyltrimethylammonium bromide. Add the mixture to a reactor equipped with a stirrer, dropping device, heating device, and reflux device. Then add 450 parts of isopropanol to the reactor. Set the initial reactor temperature to 75℃ and the stirring speed to 300 r / min. After stirring until the raw materials are completely dissolved, add 35 parts of 3-chloro-1,2-epoxypropane dropwise to the reactor over a time of 1.5 h. After the addition is complete, continue the reaction for 90 min to obtain a light yellow transparent liquid. Then connect a reflux condenser and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted 3-chloro-1,2-epoxypropane and isopropanol, obtaining a light yellow solid A1. In a separate reactor equipped with a stirrer, a dropping device, a heating device, and a reflux device, 50 parts of the solid Al prepared above were weighed and dissolved in 220 parts of isopropanol. The initial temperature of the reactor was set to 80℃ and the stirring speed to 300 r / min. After stirring until Al was completely dissolved, 20 parts of N,N,N',N'-tetramethyl-1,6-hexanediamine were added dropwise to the reactor over a time of 1.5 h. After the addition was complete, the reaction was continued for 90 min. A reflux condenser was then connected again, and unreacted N,N,N',N'-tetramethyl-1,6-hexanediamine and isopropanol were evaporated using a rotary evaporator at 50 kPa and 60℃, finally yielding a yellow entraining component A.

[0047] (2) Preparation of gas-stabilizing and enhancing component B: Take a reactor equipped with a high-speed stirrer and a dropping device, add 20 parts of nano-silica (Evonik Industries A200 model) and 4 parts of silane coupling agent (Shandong Huachen New Materials Co., Ltd. KH-560 model), set the stirring speed to 2000 r / min, and then start adding a suspension stabilizer (which consists of 1 part of xanthan gum with a viscosity of 200,000, 1 part of hydroxypropyl methylcellulose with a viscosity of 200,000 and 500 parts of deionized water), and control the dropping time to 1 hour; after the dropping is completed, continue stirring for 1 hour to obtain a solution of gas-stabilizing and reinforcing component B.

[0048] (3) Preparation of desensitizing component C: Two parts of anionic surfactant (TEGO XP 22076 from Evonik Industries), two parts of fluorocarbon surfactant (YM-3016 from Shanghai Yumu Chemical Co., Ltd.), three parts of sodium polyacrylate (average molecular weight 4 million to 5 million; 9003-04-7 from Shanghai Maclean Biochemical Technology Co., Ltd.), one part of silicone defoamer (XPJ-YJG 40% silicone defoamer from Qingzhou Xuanlang Industry and Trade Co., Ltd.) were mixed evenly with 95 parts of deionized water to obtain the desensitizing component C.

[0049] (4) Compound preparation: Weigh out the prepared air-entraining component A, air-stabilizing and reinforcing component B, and desensitizing component C according to the above-mentioned weight proportions, and mix the three evenly to obtain the low-sensitivity air-entraining agent for roller-compacted concrete in this embodiment.

[0050] Example 4 This embodiment provides a low-sensitivity air-entraining agent for roller-compacted concrete, with the following raw material weight proportions: Gas-entraining component A: 550 parts; Gas-stabilizing and enhancing component B: 350 parts; Sensitivity-reducing component C: 100 parts; The preparation steps are as follows: (1) Preparation of air-entraining component A: Weigh 150 parts of fuma-modified rosin (FR-107 model, Guangxi Wuzhou Richeng Forestry Chemical Co., Ltd.), grind it into powder, and mix it evenly with 3 parts of hexadecyltrimethylammonium bromide. Add the mixture to a reactor equipped with a stirrer, dropping device, heating device, and reflux device. Then add 450 parts of isopropanol to the reactor. Set the initial reactor temperature to 75℃ and the stirring speed to 300 r / min. After stirring until the raw materials are completely dissolved, add 35 parts of 3-chloro-1,2-epoxypropane dropwise to the reactor over a time of 1.5 h. After the addition is complete, continue the reaction for 90 min to obtain a light yellow transparent liquid. Then connect a reflux condenser and use a rotary evaporator at 50 kPa and 60℃ to evaporate the unreacted 3-chloro-1,2-epoxypropane and isopropanol, obtaining a light yellow solid A1. In a separate reactor equipped with a stirrer, a dropping device, a heating device, and a reflux device, 50 parts of the solid Al prepared above were weighed and dissolved in 220 parts of isopropanol. The initial temperature of the reactor was set to 80℃ and the stirring speed to 300 r / min. After stirring until Al was completely dissolved, 20 parts of N,N,N',N'-tetramethyl-1,6-hexanediamine were added dropwise to the reactor over a time of 1.5 h. After the addition was complete, the reaction was continued for 90 min. A reflux condenser was then connected again, and unreacted N,N,N',N'-tetramethyl-1,6-hexanediamine and isopropanol were evaporated using a rotary evaporator at 50 kPa and 60℃, finally yielding a yellow entraining component A.

[0051] (2) Preparation of gas-stabilizing and enhancing component B: Take a reactor equipped with a high-speed stirrer and a dropping device, add 20 parts of nano-silica (Evonik Industries A200 model) and 4 parts of silane coupling agent (Shandong Huachen New Materials Co., Ltd. KH-560 model), set the stirring speed to 2000 r / min, and then start adding a suspension stabilizer (which consists of 1 part of xanthan gum with a viscosity of 200,000, 1 part of hydroxypropyl methylcellulose with a viscosity of 200,000 and 500 parts of deionized water), and control the dropping time to 1 hour; after the dropping is completed, continue stirring for 1 hour to obtain a solution of gas-stabilizing and reinforcing component B.

[0052] (3) Preparation of desensitizing component C: Two parts of anionic surfactant (TEGO XP 22076 from Evonik Industries), two parts of fluorocarbon surfactant (YM-3016 from Shanghai Yumu Chemical Co., Ltd.), three parts of sodium polyacrylate (average molecular weight 4 million to 5 million; 9003-04-7 from Shanghai Maclean Biochemical Technology Co., Ltd.), one part of silicone defoamer (XPJ-YJG 40% silicone defoamer from Qingzhou Xuanlang Industry and Trade Co., Ltd.) were mixed evenly with 95 parts of deionized water to obtain the desensitizing component C.

[0053] (4) Compound preparation: Weigh out the prepared air-entraining component A, air-stabilizing and reinforcing component B, and desensitizing component C according to the above-mentioned weight proportions, and mix the three evenly to obtain the low-sensitivity air-entraining agent for roller-compacted concrete in this embodiment.

[0054] Comparative Example 1 The only difference from Example 3 is that the fuma modified rosin is replaced with the same amount of acrylic rosin (AR-120 model from Guangxi Wuzhou Richeng Forest Products Chemical Co., Ltd.).

[0055] Comparative Example 2 The only difference from Example 3 is that nano-silica is not added in step (2).

[0056] Comparative Example 3 The only difference from Example 3 is that sodium polyacrylate is not added in step (3).

[0057] Comparative Example 4 The only difference from Example 3 is that the weight ratio of each component of the air-entraining agent is adjusted in this comparative example, specifically: 400 parts of air-entraining component A, 400 parts of gas-stabilizing and enhancing component B, and 200 parts of desensitizing component C; other raw materials, preparation steps and process parameters are consistent with those in Example 3.

[0058] Commercially available example 1 The solid air-entraining agent, sodium rosinate, model OP-08, is used from Henan Qiantel Chemical Products Co., Ltd.

[0059] Commercial Example 2 The air-entraining agent used is Clariant AE-80 from Nanjing Qinhai Trading Co., Ltd.

[0060] Performance testing 1. Test raw materials and mixing ratio: The performance of the air-entraining agents obtained in the examples and comparative examples was tested by roller-compacted concrete tests. The cement used was Esheng P·O 42.5 cement; the fineness modulus of the manufactured sand was 2.5, the stone powder content was 18% (the proportion of stone powder with a particle size of less than 0.15mm in the manufactured sand), and the methylene blue MB value was 1.0; the aggregate was crushed stone with a gradation of 5mm-20mm and 20mm-40mm. The formula for a single ton of naphthalene-based water-reducing agent is: naphthalene masterbatch (4A): calcium lignosulfonate: retarder (sodium gluconate) = 800:160:40; Water-reducing agent dosage = water-reducing agent mass ÷ (cement mass + fly ash mass); The mix proportions of roller-compacted concrete are designed according to the conventional hydraulic roller-compacted concrete mix proportions (see Table 1 for details).

[0061] Table 1. Mix proportions of roller-compacted concrete (kg / m³) 3 ) 2. Testing Method: By adjusting the dosage of air-entraining agent in the examples, comparative examples, and commercially available examples, the air content of roller-compacted concrete with a water-reducing agent dosage of 0.5% was controlled at 4%~5%. Based on this, the water-reducing agent dosage was increased to 0.6%, and VC value, air content, impermeability coefficient, freeze-thaw cycles, and compressive strength (7 days, 28 days, 90 days) were tested according to DL / T 5433-2024 "Test Procedure for Roller-Compacted Concrete in Hydraulic Engineering". Sample preparation, molding, and curing were performed according to DL / T 5433-2024 "Test Procedure for Roller-Compacted Concrete in Hydraulic Engineering". The number of freeze-thaw cycles was the number of cycles corresponding to a mass loss rate exceeding 5%.

[0062] 3. Test Results and Analysis: The test results are shown in Table 2: Table 2 As shown in Table 2: (1) When the water-reducing agent dosage increases from 0.5% to 0.6%, the VC value decreases accordingly. The air-entraining agent prepared in the present invention has a significantly smaller fluctuation range in air content affected by VC value than the comparative example and the commercially available example, indicating that it is less sensitive to VC value. (2) Under the action of the air-entraining agent in the example, the air content loss of the roller-compacted concrete is less after 1 hour, and the bubble stability is stronger; (3) The concrete impermeability coefficient of the embodiment is significantly lower than that of the comparative example and the commercially available example, the number of freeze-thaw cycles is significantly increased, and the freeze-thaw resistance and impermeability performance are better; (4) The 7-day, 28-day and 90-day compressive strength of the concrete in the example were higher than those of the comparative example and the commercially available example, and the early and late mechanical properties were better.

[0063] Fumar modified rosin is the core raw material that ensures the rigidity of air-entraining component A and the surface activity of the twin-type surface. The ternary phenanthrene ring in its molecular structure gives the bubble film excellent stability, which is suitable for the working conditions of high viscosity and high vibration intensity of roller-compacted concrete paste. In Comparative Example 1 of this invention, the fuma modified rosin in air-entraining component A in Example 1 was replaced with acrylic rosin. Due to the difference in molecular structure, acrylic rosin cannot form equally stable bubbles, resulting in a significant decrease in the freeze-thaw resistance and impermeability of concrete.

[0064] In Comparative Example 2, after removing nano-silica from the gas-stabilizing and reinforcing component B, air bubbles easily migrate and coalesce during compaction, resulting in a significant increase in air content loss. Simultaneously, the cement hydration lacks anchoring points, leading to a marked decrease in the early and late stages of concrete compressive strength. In Comparative Example 3, after removing sodium polyacrylate from the desensitizing component C, the air-entraining agent's air content exceeds the design range with slight fluctuations in VC value, drastically increasing the difficulty of quality control at the mixing plant. In Comparative Example 4, adjusting the proportions of the three components resulted in insufficient air-entraining component and excessive gas-stabilizing component, leading to low foaming efficiency and excessively high slurry viscosity, significantly deteriorating overall performance.

[0065] In summary, the low-sensitivity air-entraining agent of the present invention can significantly improve the workability stability, early and late mechanical properties and durability of roller-compacted concrete, reduce the sensitivity of air content to VC value, and meet the application requirements of roller-compacted concrete in water conservancy projects such as dams.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An air-entraining agent for roller-compacted concrete, characterized in that, The raw materials include the following raw material components in parts by weight: Gas-entraining component A: 450-550 parts; Gas-stabilizing and enhancing component B: 250-350 parts; Sensitivity-reducing component C: 100-300 parts; The preparation method of the air-entraining component A includes the following steps: (1) Fumar modified rosin was esterified with 3-chloro-1,2-epoxypropane in the presence of hexadecyltrimethylammonium bromide to obtain an intermediate; (2) The intermediate is subjected to a quaternization reaction with a binary aliphatic tertiary amine to obtain the air-entraining component A; The preparation method of the gas-stabilizing and enhancing component B includes the following steps: adding a suspension stabilizer to a mixture of nano-silica and silane coupling agent to obtain the gas-stabilizing and enhancing component B; The desensitizing component C is composed of the following components in the following weight ratio: anionic surfactant: fluorocarbon surfactant: sodium polyacrylate: silicone defoamer: deionized water = (1-3): (1-3): (2-4): (0.5-1.5): 95; The suspension stabilizer is composed of xanthan gum, hydroxypropyl methylcellulose and deionized water; The weight ratio of the fuma-modified rosin to 3-chloro-1,2-epoxypropane is (120-180):(30-40); the binary aliphatic tertiary amine is N,N,N',N'-tetramethyl-1,6-hexanediamine, and the weight ratio of the intermediate to N,N,N',N'-tetramethyl-1,6-hexanediamine is (45-55):(15-25); The weight ratio of the nano-silica, silane coupling agent, xanthan gum, hydroxypropyl methylcellulose and deionized water is (15-25):(3-5):(0.5-1.5):(0.5-1.5):500; The weight ratio of the hexadecyltrimethylammonium bromide to the fuma-modified rosin is (2-4):(120-180).

2. The air-entraining agent for roller-compacted concrete according to claim 1, characterized in that, The esterification reaction is carried out at a temperature of 70-80℃ for a time of 60-120 min; the quaternization reaction is carried out at a temperature of 75-85℃ for a time of 60-120 min.

3. The air-entraining agent for roller-compacted concrete according to claim 1, characterized in that, The xanthan gum has a viscosity of 150,000-200,000, and the hydroxypropyl methylcellulose has a viscosity of 150,000-200,000.

4. The method for preparing the air-entraining agent for roller-compacted concrete as described in any one of claims 1-3, characterized in that, Includes the following steps: The air-entraining component A, the air-stabilizing and reinforcing component B, and the sensitivity-reducing component C are mixed to obtain the air-entraining agent for roller-compacted concrete.

5. The application of the air-entraining agent for roller-compacted concrete prepared by the method described in claim 4 in roller-compacted concrete.

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