Anti-adsorption and anti-mud water reducing agent for recycled coarse aggregate concrete and preparation thereof

Abstract

The application relates to an anti-adsorption and anti-mud type water reducing agent suitable for recycled coarse aggregate concrete and a preparation method thereof, which is composed of the following components in parts by weight and takes the total weight as 100 parts: fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder 20-40 parts, mud resistance regulator 4-10 parts, dispersant 2-8 parts, polycarboxylic acid water reducing agent 20-30 parts, auxiliary agent 4-12 parts, retarder 5-7 parts, alkaline solution 2-10 parts, and the rest is deionized water. The anti-adsorption and anti-mud type water reducing agent introduces multiple functional groups such as fatty alcohol, carboxyl and methoxysilane, optimizes the dispersion effect of cement particles, adjusts the adsorption of recycled aggregate to the water reducing agent, and reduces the activity of matrix anions (Cl ‑ , SO4 2‑ ). This technical innovation helps to improve the working performance of recycled concrete, promotes cement hydration, enhances the chloride ion erosion resistance of concrete, has a simple preparation process, has significant economic effect and environmental benefit, and has a wide engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, specifically relating to an anti-adsorption mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete and its preparation. Background Technology

[0002] In recent years, with the rise of environmental protection concepts in the construction industry, recycled aggregates have received widespread attention as a sustainable building material. The application of recycled aggregates can not only reduce dependence on natural aggregates but also reduce construction waste emissions, thereby reducing environmental pollution. However, despite the environmental advantages of recycled aggregates, their widespread application in concrete faces new and serious challenges. Because recycled aggregates are mainly composed of waste concrete or construction waste, they have a high mud content, meaning their surface is covered with a large number of fine clay particles, silt, and dust particles. This results in strong adsorption of water-reducing agents, reducing the number of admixture molecules used to disperse cement particles, thus decreasing the dispersing effect of the admixtures. This leads to poor workability and high shrinkage rates in fresh concrete, making it difficult to meet the requirements for transportation, pumping, and construction. While increasing the dosage of water-reducing agents can improve the performance of fresh concrete to some extent, it increases costs and can also cause severe segregation and excessively long setting times.

[0003] Chinese patent CN116081974A discloses a concrete workability modifier, its preparation method, and its application, belonging to the field of concrete admixture technology. In this invention, the fatty alcohol polyoxyethylene ether, polyvinyl alcohol, sodium acetate, and modified starch are used in combination to improve the workability of concrete, but this reduces the strength and fluidity of the concrete. Furthermore, the optimized design of the fatty alcohol polyoxyethylene ether focuses too much on the single effect of workability, neglecting the influence of the fatty alcohol polyoxyethylene ether on the cement hydration reaction and the chloride ion erosion resistance of the concrete specimens.

[0004] Chinese patent CN117209686A discloses a low surface tension polycarboxylate superplasticizer and its preparation method. This patent utilizes the tunable structure of fatty alcohol polyoxyethylene ethers, altering the hydrophilic-lipophilic balance by changing the EO addition number and alkyl chain length, and incorporating this into the polycarboxylate superplasticizer structure. Through structure-activity relationships, this reduces the surface tension of the polycarboxylate superplasticizer solution, thereby reducing cement drying shrinkage. However, the end-capped fatty alcohol polyoxyethylene ether functional monomers may decompose or degrade under prolonged storage or high-temperature conditions, affecting the performance stability of the superplasticizer. Furthermore, the use of end-capped fatty alcohol polyoxyethylene ether functional monomers may reduce the superplasticizer's dispersion performance in concrete, resulting in poor mud-blocking effect, and consequently affecting construction processes and water-reducing effects.

[0005] While traditional water-reducing agents can improve the fluidity of recycled concrete to some extent, they do not significantly address the issue of adsorption of these agents by recycled aggregates. Furthermore, recycled aggregates have a high specific surface area, resulting in strong water absorption and reduced free water content, thus decreasing the degree of cement hydration. Therefore, to ensure the stable development of national infrastructure construction, improve the construction quality of recycled concrete, and promote the sustainable development of the water-reducing agent field, it is imperative to develop an anti-adsorption, mud-inhibiting water-reducing agent suitable for recycled coarse aggregates. Summary of the Invention

[0006] The purpose of this invention is to provide an anti-adsorption, mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete and its preparation method. This is achieved by optimizing the dispersion effect of cement particles, adjusting the adsorption of recycled aggregate on the water-reducing agent, and reducing the matrix anions (Cl-, SO42-). 2- The activity of the recycled concrete is used to improve its workability, promote cement hydration, and enhance its resistance to chloride ion erosion.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention provides a raw material for preparing fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, characterized in that, based on a total weight of 100 parts, it is composed of the following raw material components in parts by weight: fatty alcohol 20-40 parts, ethoxylating agent 10-20 parts, alkaline catalyst 5-10 parts, solvent 8-18 parts, azelaic acid 2-10 parts, trimethoxysilane 12-24 parts, and the remainder being deionized water.

[0009] Optionally, the proportions of each raw material are as follows:

[0010] Fatty alcohols: 30 parts;

[0011] Ethoxylating agent: 15 parts;

[0012] Alkali catalyst: 8 parts;

[0013] Solvent: 13 parts;

[0014] Azelaic acid: 6 parts;

[0015] Trimethoxysilane: 18 parts;

[0016] Deionized water: 10 parts.

[0017] Furthermore, the fatty alcohol is one or more of hexanol, octanol, hexadecyl alcohol, or octadecanol.

[0018] Furthermore, the fatty alcohol is composed of hexanol, octanol, and hexadecyl alcohol in a mass ratio of 1:1:2. Fatty alcohol molecules of different lengths have different solubilities, surface activities, and lubricating properties. By compounding the three fatty alcohols, good surface activity and lubricating properties can be achieved while maintaining certain solubility and stability, making the prepared powder more widely applicable. In addition, by optimizing the compounding design according to this mass ratio, hexadecyl alcohol, which has a high cross-linking ability, can be mixed with hexanol and octanol, which have lower cross-linking abilities. This compounding method can improve the cross-linking ability between fatty alcohol molecules, avoid excessive cross-linking between alcohol molecules, thereby balancing the polymerization reaction rate and contributing to the formation of uniform fatty alcohol polyoxyethylene ethers.

[0019] Furthermore, the ethoxylating agent is produced by stepwise addition polymerization of ethylene oxide with water or ethylene glycol, and has a molecular weight of 2000-3000, and is in a semi-solid state.

[0020] Furthermore, the alkaline catalyst is one or both of sodium hydroxide or potassium hydroxide, and its function is to regulate the rate and degree of polymerization of the polymerization reaction.

[0021] Furthermore, the solvent is one or more of ethyl acetate, dimethylformamide, aminopropanol, or toluene, which can be used as a solvent in the chemical modification process to improve the homogeneity of the reaction system.

[0022] The second technical solution of the present invention provides a method for preparing fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, comprising the following steps:

[0023] (1) Add solvent to a four-necked flask, then add fatty alcohol, ethoxylation agent, alkaline catalyst and deionized water in sequence, mix well to prepare a reaction solution, carry out polymerization reaction by heating and ultraviolet light irradiation, and stir evenly to obtain fatty alcohol polyoxyethylene ether.

[0024] (2) Add azelaic acid to the container, stir magnetically, introduce nitrogen gas, heat to 80-120℃, and react at a constant temperature for 3-5 hours to obtain fatty alcohol polyoxyethylene ether nonanoate.

[0025] (3) Add trimethoxysilane to the container, stir magnetically, introduce oxygen, heat to 70-85℃, and react at a constant temperature for 2-4 hours to obtain trimethoxysilane of fatty alcohol polyoxyethylene ether nonanoate.

[0026] (4) After the reaction is complete, the product is cooled to room temperature and then transferred to a beaker. Next, it is placed in a vacuum oven and dried at 60°C. After drying, the obtained fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is scraped out with a spatula and stored in a brown clamp-top sample bottle.

[0027] Furthermore, in step (1), the heat treatment temperature is 60-100℃, and the time is 2-4 hours. The ultraviolet irradiation is used to stimulate the generation of free radicals in the reaction, accelerate the polymerization reaction between monomers, and increase the polymerization rate.

[0028] Furthermore, in step (2), the magnetic stirring speed is 200-400 r / min, and the stirring time is 1-2 h.

[0029] Furthermore, in step (3), the magnetic stirring speed is 250-350 r / min and the stirring time is 1.5-3 h.

[0030] Furthermore, the molecular formula of the fatty alcohol polyoxyethylene ether is:

[0031]

[0032] Where R is a saturated hydroxyl group, n is the addition number of ethylene oxide, and n is an integer between 16 and 20.

[0033] Furthermore, the molecular formula of the aforementioned azelaic acid is:

[0034]

[0035] Furthermore, the molecular formula of the trimethoxysilane is:

[0036]

[0037] Furthermore, the esterification reaction involved in step (2) is as follows:

[0038]

[0039] Furthermore, the substitution reaction involved in step (3) is as follows:

[0040]

[0041] The aforementioned fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, as a basic component of water-reducing agents, contains multiple functional groups (fatty alcohol groups, carboxyl groups, and methoxysilane groups), thereby improving the workability and durability of recycled coarse aggregate concrete. Its mechanism of action mainly includes the following aspects:

[0042] (1) Fatty alcohol groups: Fatty alcohol groups mainly promote the dispersion of cement particles and the bonding of water-reducing agents with the surface of cement particles through their hydrophilic properties. Fatty alcohol groups reduce the solid-liquid interfacial energy of the cement surface, thereby reducing the total energy of the cement-water dispersion system and increasing the viscosity of the system, thus promoting the dispersion of cement particles. The increase in viscosity helps to reduce the collision frequency and shear force between cement particles, reduce the tendency of particles to aggregate, and thus promote the effective dispersion of cement particles. Secondly, fatty alcohol groups have hydrophilic hydroxyl groups, which can form hydrogen bonds with water molecules. By reducing the surface tension of water, the water-reducing agent can better wet the surface of cement particles, thereby achieving the water-reducing effect. When the fatty alcohol groups in the water-reducing agent interact with the surface of cement particles, the hydroxyl groups combine with the oxygen atoms on the surface of cement particles through hydrogen bonds, thereby increasing the bonding ability of the water-reducing agent with the surface of cement particles.

[0043] (2) Carboxyl group: carboxylate ion (-COO) - ) is a functional group with a negative charge and strong polarity, which interacts with the cations (Ca) of the mud particles on the surface of recycled aggregate. 2+ Mg 2+ Ionic bonds are formed, reducing the adsorption of water-reducing agents by high-valence metal ions in recycled aggregate particles. Furthermore, carboxyl groups can bind to active groups such as hydroxyl and silicate groups on the surface of recycled aggregate through hydrogen bonding, forming a "locking" effect that makes it difficult for particulate matter on the surface of recycled aggregate to move. This "contraction" effect results in poor dispersion of particulate matter on the surface of recycled aggregate in cement paste, thereby reducing the adsorption of water-reducing agents by recycled aggregate.

[0044] (3) Methoxysilyl group: The methoxysilyl group (-OCH3) has a large steric volume. When introduced into the water-reducing agent molecule, it increases the steric hindrance between molecules. This steric hindrance effect and electronic effect help reduce the activity of the anion, making the anion (Cl... - SO4 2- The transport of these substances on the surface of cement particles is inhibited, reducing the formation of expansion hydration products (CaCl2, CaSO4), thereby reducing the risk of expansion failure of concrete.

[0045] The third technical solution of the present invention provides an anti-adsorption and mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete, characterized in that, based on a total weight of 100 parts, it is composed of the following raw material components in parts by weight: 20-40 parts of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, 4-10 parts of mud-inhibiting regulator, 2-8 parts of dispersant, 20-30 parts of polycarboxylate water-reducing agent, 4-12 parts of additives, 5-7 parts of retarder, 2-10 parts of alkaline solution, and the remainder being deionized water.

[0046] Optionally, the proportions of each raw material are as follows:

[0047] Fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder: 30 parts;

[0048] Sludge inhibitor: 7 parts;

[0049] Dispersant: 5 parts;

[0050] Polycarboxylate superplasticizer: 25 parts;

[0051] Additives: 8 parts;

[0052] Retarder: 6 parts;

[0053] Alkaline solution: 6 parts;

[0054] Deionized water: 13 parts.

[0055] Furthermore, the mud-inhibiting agent is one or more of polyvinyl alcohol, polyethylene glycol diacrylate, or sulfonated lignin. By adsorbing onto the surface of cement particles, the mud-inhibiting agent in the water-reducing agent reacts chemically with the carboxyl groups (-COOH) in the trimethoxysilane of fatty alcohol polyoxyethylene ether nonanoate, forming a chemisorption effect. This effect helps reduce the adsorption capacity of the water-reducing agent on the surface of recycled aggregate. In addition, the mud-inhibiting agent can also compete for limited adsorption sites on the surface of recycled aggregate, reducing the adsorption of the water-reducing agent on the surface of recycled aggregate.

[0056] Furthermore, the dispersant is sodium methylene bisnaphthalene sulfonate or methoxyethanolamine, which improves the dispersion stability of the components in concrete, reduces particle agglomeration, and thus increases the uniformity and fluidity of concrete.

[0057] Furthermore, the polycarboxylate superplasticizer is the PCA-9 series of high-efficiency polycarboxylate superplasticizers produced by Jiangsu Subote.

[0058] Furthermore, the additive is sodium methacrylate sulfonate, whose molecules carry a negative charge, while the surfaces of recycled aggregate and cement particles carry a positive charge. When sodium methacrylate sulfonate is added to recycled coarse aggregate concrete, its negatively charged molecules (-SO3Na) react with the positively charged (Ca) surfaces of the recycled aggregate and cement particles. 2+ It generates an electrostatic attraction. This force helps sodium methacrylate molecules form an adsorption layer on the surface of recycled aggregates and cement particles, thereby improving the slump retention and fluidity of recycled coarse aggregate concrete. Secondly, as a high-performance additive, sodium methacrylate can reduce cement usage, lower energy consumption and environmental pollution in the concrete production process, and contribute to achieving the goals of green building and sustainable development.

[0059] Furthermore, the retarder is one or both of sodium gluconate and potassium polyvinyl sulfate.

[0060] Furthermore, the alkaline solution is an industrial-grade sodium hydroxide or potassium hydroxide solution with a mass fraction of 20%-40%.

[0061] The fourth technical solution of the present invention provides a method for preparing an anti-adsorption and mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete, comprising the following steps:

[0062] (1) Mix the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, mud inhibitor and some deionized water thoroughly and completely dissolve them;

[0063] (2) Continue to add dispersant, polycarboxylate superplasticizer and additives, and stir thoroughly in a water bath at 60-70℃ to ensure that the components are mixed evenly;

[0064] (3) Then add alkaline solution and continue heating and stirring for 1-2 hours to adjust the pH of the system to 9.5-10.5;

[0065] (4) Finally, add the retarder and the remaining deionized water, stir thoroughly and mix evenly, then cool and filter to remove impurities, thus obtaining the anti-adsorption mud-blocking water-reducing agent.

[0066] The fifth technical solution of the present invention provides a recycled coarse aggregate concrete prepared by an anti-adsorption and mud-blocking water-reducing agent, comprising the following raw material components in parts by weight: 260-300 parts of cement; 20-40 parts of recycled wind turbine blade powder; 1000-1200 parts of recycled coarse aggregate; 600-880 parts of sand; 5-15 parts of the anti-adsorption and mud-blocking water-reducing agent as described above; and 160-200 parts of water.

[0067] Furthermore, the preferred formulation of this concrete is as follows:

[0068] Cement: 280 parts;

[0069] Regenerated fan blade powder: 30 parts;

[0070] Recycled coarse aggregate: 1100 parts;

[0071] Sand: 740 portions;

[0072] 10 parts of any of the above-mentioned anti-adsorption and anti-mud-blocking water-reducing agents;

[0073] Water: 180 portions.

[0074] The cement is PO 42.5 low-alkali cement with a 28-day compressive strength of 48.2 MPa, and is produced by Minhe Qilianshan Cement Co., Ltd.

[0075] The recycled wind turbine blade powder is made from waste wind turbine blades, using collected epoxy resin powder and glass fiber powder generated during the crushing and preparation process. It is produced by Xilinhot Chengfei Wind Power Equipment Co., Ltd. During concrete mixing, epoxy resin micropowder exhibits good surface activity and contains various functional groups, such as hydroxyl and amino groups. The anti-adsorption, mud-inhibiting water-reducing agent provided in this patent introduces functional groups such as fatty alcohols, carboxyl groups, and methoxysilanes, which can produce unique interaction effects. This inhibits the direct physical and electrochemical adsorption between the water-reducing agent molecules and the recycled aggregate, thereby reducing waste and improving its effectiveness. Furthermore, the epoxy resin micropowder can interact with the silicate groups of cement particles, hindering the cement's gelation reaction. This effect can regulate the hardening process of cement, delaying the initial and final setting times, thus improving the fluidity of the concrete.

[0076] Furthermore, the glass fiber powder contained in the regenerated wind turbine blade powder possesses excellent activity and filling properties, which can effectively improve the performance of concrete. Firstly, the glass fiber powder has high strength and high modulus, increasing the tensile strength and impact resistance of concrete. Its dispersion within the concrete increases the interfacial effect, thereby enhancing the concrete's strength. Secondly, the introduction of glass fiber powder can improve the crack resistance of concrete. Due to the high tensile strength of glass fibers, they can disperse stress within the concrete, reducing the formation of microcracks and fissures, thus improving the durability of the concrete.

[0077] The recycled coarse aggregate is crushed stone material formed from construction and demolition waste; the recycled coarse aggregate adopts a continuous gradation of (5mm-10mm):(10mm-16mm):(16mm-25mm) = 2:3:5, with an apparent density of 2472.0 kg / m³. 3 The bulk density is 1498.0 kg / m³. 3 The water absorption rate is 3.68%, and the crushing index is 16.8%.

[0078] The sand is natural river sand with a fineness modulus of 2.4 and an average particle size of 0.36 mm.

[0079] The water mentioned is tap water supplied to the laboratory.

[0080] Alternatively, the method for preparing recycled coarse aggregate concrete may include the following steps:

[0081] (1) Weigh and sample cement, recycled wind turbine blade powder, recycled coarse aggregate, sand, anti-adsorption mud-blocking water-reducing agent and water according to the weight in the mix proportion. Pour cement and recycled wind turbine blade powder into a concrete planetary mixer for the first mixing at a speed of 120 r / min for 2 min to obtain the first mixture;

[0082] (2) Add sand and recycled coarse aggregate to the first mixture for a second mixing. The mixing speed is 120 r / min and the mixing time is 2 min to obtain the second mixture.

[0083] (3) Add water and anti-adsorption mud-blocking water-reducing agent to the second mixture for a third stirring. The stirring speed is 100r / min and the stirring time is 2min to obtain a recycled coarse aggregate fresh concrete mixture.

[0084] (4) Pour the recycled coarse aggregate fresh concrete mixture into test specimens according to the specifications and compact it. According to GB / T50081-2019, cure the specimens under standard curing conditions until the specimens reach the specified test age.

[0085] Compared with the prior art, the present invention has the following advantages:

[0086] (1) The optimized processed fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder can be chemically modified to enhance its compatibility with recycled coarse aggregate. The functional groups (carboxyl groups) introduced by chemical modification can interact more strongly with the mud particles on the surface of recycled aggregate. This interaction can promote the synergistic coagulation effect of water-reducing agent and active groups such as hydroxyl and silicate groups on the surface of recycled coarse aggregate, forming a stable gel structure. In addition, the optimized processed fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid can reduce its affinity with the surface of recycled aggregate by changing the charge and polarity of the solid surface, thereby weakening the adsorption of water-reducing agent by recycled aggregate, maximizing the dispersion and coating effect of water-reducing agent, reducing the friction and aggregation force between cement particles, and thus improving the fluidity and workability of concrete.

[0087] (2) Through precise proportioning and controlled preparation process, the mud-inhibiting regulator can chemically react with the carboxyl groups (-COOH) in trimethoxysilane of fatty alcohol polyoxyethylene ether nonanoate to form chemical bonds or adsorption, thereby changing its surface energy and mutual adsorption forces, thus reducing the adsorption of water-reducing agents by recycled aggregates. This will maximize the water-reducing effect of the water-reducing agent. By reducing the surface tension of water, the water-reducing agent can achieve optimal dispersion and encapsulation in concrete, reducing the friction and aggregation forces between cement particles, and further improving the workability of concrete.

[0088] (3) During the long-term use of concrete, the service life of concrete is reduced due to the corrosive effects of chloride ions and sulfates. This invention introduces methoxysilane groups, which inhibit anion transport through steric hindrance and electronic effects, reducing the formation of expansion hydration products (such as CaCl2 and CaSO4), thereby reducing the risk of concrete expansion failure and extending its service life. Compared with traditional anti-corrosion materials, the water-reducing agent of this invention has better application potential.

[0089] (4) The application of the anti-adsorption mud-inhibiting water-reducing agent of the present invention can not only improve the performance of concrete, but also generate significant benefits, and the preparation method is simple. By adjusting the water absorption characteristics of recycled aggregate and reducing its adsorption of water-reducing agent, the amount of water-reducing agent used is optimized, thereby saving raw material consumption. In addition, since the water-reducing agent can improve the workability and durability of concrete, it reduces energy consumption and labor costs during construction. Therefore, the application of water-reducing agent has significant economic and environmental benefits, providing technical support for the sustainable development of engineering projects. Attached Figure Description

[0090] Figure 1 This is a schematic diagram of the preparation process of the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder of the present invention.

[0091] Figure 2 This is a schematic diagram of the preparation process of the anti-adsorption mud-inhibiting water-reducing agent of the present invention. Detailed Implementation

[0092] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0093] The sources of raw materials used in the following embodiments and comparative examples are shown in Table 1.

[0094] Table 1 shows the sources of raw materials in the examples.

[0095]

[0096]

[0097] Unless otherwise specified, all other raw materials or processing techniques are commercially available materials or conventional processing techniques in the field.

[0098] Example 1

[0099] (1) A raw material for preparing a fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, characterized in that, based on a total weight of 100 parts, it is composed of the following raw material components in parts by weight: fatty alcohol 30 parts; ethoxylation agent 15 parts; alkaline catalyst 8 parts; solvent 13 parts; azelaic acid 6 parts; trimethoxysilane 18 parts; deionized water 10 parts.

[0100] The fatty alcohol is composed of hexanol, octanol, and hexadecyl alcohol, with a mass ratio of hexanol:octanol:hexadecyl alcohol = 1:1:2; the ethoxylation agent is produced by the stepwise addition polymerization of ethylene oxide with water or ethylene glycol, with a molecular weight of approximately 2500, and is in a semi-solid state; the alkaline catalyst is sodium hydroxide; and the solvent is dimethylformamide.

[0101] Specifically, the preparation steps of a fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder are as follows: ① Add solvent to a four-necked flask, then add fatty alcohol, ethoxylating agent, alkaline catalyst and deionized water in sequence, mix evenly to prepare a reaction solution, and carry out polymerization reaction by heating and ultraviolet irradiation, stirring evenly to obtain fatty alcohol polyoxyethylene ether; ② Add azelaic acid to a container, stir magnetically at a speed of 300 r / min for 1.5 h, then introduce nitrogen gas, raise the temperature to 100℃, and react at a constant temperature for 4 h to obtain fatty alcohol polyoxyethylene ether nonanoate; ③ Add trimethoxysilane to a container, stir magnetically at a speed of 300 r / min for 2.25 h, then introduce oxygen gas, raise the temperature to 78℃, and react at a constant temperature for 3 h to obtain fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane; ④ After the reaction is completed, cool the product to room temperature and then transfer it to a beaker. Then, place it in a vacuum oven and dry it at 60℃. After drying, the obtained fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder was scraped out with a spatula and stored in a brown clamp-mouth sample bottle.

[0102] (2) An anti-adsorption mud-blocking water-reducing agent suitable for recycled coarse aggregate concrete, which is composed of the following raw material components in parts by weight, based on a total weight of 100 parts: 30 parts of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, 7 parts of mud-blocking regulator, 5 parts of dispersant, 25 parts of polycarboxylate water-reducing agent, 8 parts of additives, 6 parts of retarder, 6 parts of alkaline solution, and 13 parts of deionized water.

[0103] The fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder was prepared according to the above raw materials and preparation steps; the mud inhibitor was polyvinyl alcohol; the dispersant was sodium methylene bisnaphthalene sulfonate; the water-reducing agent was PCA-9 series polycarboxylate high-efficiency water-reducing agent produced by Jiangsu Subote New Material Technology Co., Ltd.; the additive was sodium methpropylene sulfonate; the retarder was potassium sulfate of polyethylene; and the alkaline solution was 30% by mass industrial grade sodium hydroxide solution.

[0104] Specifically, a method for preparing an anti-adsorption mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete includes the following steps: ① Thoroughly mix and completely dissolve fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, mud-inhibiting regulator, and a portion of deionized water; ② Continue to add dispersant, polycarboxylate water-reducing agent, and additives, and thoroughly stir under a water bath at 65°C to ensure uniform mixing of all components; ③ Subsequently add alkaline solution, and continue heating and stirring for 1.5 hours to adjust the pH value of the system to 10; ④ Finally, add retarder and the remaining deionized water, thoroughly stir and uniformly mix, then cool and filter to remove impurities, thereby obtaining the anti-adsorption mud-inhibiting water-reducing agent.

[0105] (3) A recycled coarse aggregate concrete prepared by an anti-adsorption mud-blocking water-reducing agent, comprising the following raw material components in parts by weight: 280 parts of cement; 30 parts of recycled wind turbine blade powder; 1100 parts of recycled coarse aggregate; 740 parts of sand; 10 parts of the anti-adsorption mud-blocking water-reducing agent as described above; and 180 parts of water.

[0106] The cement used is PO 42.5 low-alkali cement; the recycled wind turbine blade powder is made from waste wind turbine blades, using collected epoxy resin powder and glass fiber powder generated during the crushing and preparation process; the recycled coarse aggregate is crushed stone material formed from construction and demolition waste; the recycled coarse aggregate adopts a continuous gradation of (5mm-10mm):(10mm-16mm):(16mm-25mm)=2:3:5; the sand is natural river sand; and the water is tap water supplied to the laboratory.

[0107] Optionally, the preparation steps of recycled coarse aggregate concrete with the addition of an anti-adsorption mud-inhibiting water-reducing agent are as follows: ① Weigh and sample cement, recycled wind turbine blade powder, recycled coarse aggregate, sand, anti-adsorption mud-inhibiting water-reducing agent, and water according to the weight ratio specified in the mix design. Pour cement and recycled wind turbine blade powder into a concrete planetary mixer for the first mixing at a speed of 120 r / min for 2 min to obtain a first mixture; ② Add sand and recycled coarse aggregate to the first mixture for a second mixing at a speed of 120 r / min for 2 min to obtain a second mixture; ③ Mix water and the anti-adsorption mud-inhibiting water-reducing agent and add them to the second mixture for a third mixing at a speed of 100 r / min for 2 min to obtain a fresh concrete mixture with recycled coarse aggregate; ④ Pour the fresh concrete mixture with recycled coarse aggregate into test specimens according to specifications and compact it with vibration. According to GB / T 50081-2019, cure the specimens under standard curing conditions until they reach the specified test age.

[0108] Example 2

[0109] Compared with Example 1, most of the contents are the same, except that the fatty alcohol used in the preparation of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is replaced with a mixture of equal parts by mass of hexanol and octanol (mass ratio of 1:1).

[0110] Example 3

[0111] Compared with Example 1, most of the contents are the same, except that the fatty alcohol used in the preparation of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is replaced with a mixture of equal parts by mass of hexanol and octadecyl alcohol (mass ratio of 1:1).

[0112] Example 4

[0113] Compared with Example 1, most of the contents are the same, except that the fatty alcohol used in the preparation of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is replaced with an equal mass of hexanol.

[0114] Example 5

[0115] Compared with Example 1, most of the contents are the same, except that the amount of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder was changed to 20 parts in the preparation process of the anti-adsorption mud-blocking water-reducing agent.

[0116] Example 6

[0117] Compared with Example 1, most of them are the same, except that the mud-blocking regulator is changed from polyvinyl alcohol to an equal mass of polyethylene glycol diacrylate in the preparation process of the anti-adsorption mud-blocking water-reducing agent.

[0118] Example 7

[0119] Compared with Example 1, most of the contents are the same, except that the dispersant is changed from sodium methylene bisnaphthalene sulfonate to an equal mass of methoxyethanolamine in the preparation of the anti-adsorption mud-blocking water-reducing agent.

[0120] Example 8

[0121] Compared with Example 1, most of the contents are the same, except that the anti-adsorption mud-blocking water-reducing agent is replaced with an equal mass of PCA-9 series polycarboxylate high-efficiency water-reducing agent in the preparation of recycled coarse aggregate concrete.

[0122] Example 9

[0123] The process is largely the same as in Example 1, except that the amount of recycled wind turbine blade powder is changed to 20 parts in the preparation of recycled coarse aggregate concrete.

[0124] Comparative Example 1

[0125] The majority of the components are the same as in Example 1, except that the fatty alcohol is omitted from the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder.

[0126] Comparative Example 2

[0127] Compared to Example 1, most of the components are the same, except that in the preparation of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, dimethylformamide in the solvent is replaced with an equal mass of water.

[0128] Comparative Example 3

[0129] Compared with Example 1, most of the contents are the same, except that the addition of trimethoxysilane is omitted in the preparation of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder.

[0130] Comparative Example 4

[0131] The process is largely the same as in Example 1, except that the prepared fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is stored in a glass bottle.

[0132] Comparative Example 5

[0133] Compared with Example 1, most of them are the same, except that the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder used in the preparation of the anti-adsorption mud-blocking water-reducing agent is replaced with an equal mass of allyl alcohol polyoxyethylene ether.

[0134] Comparative Example 6

[0135] Compared with Example 1, most of them are the same, except that the addition of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is omitted in the preparation of the anti-adsorption mud-blocking water-reducing agent.

[0136] Comparative Example 7

[0137] Compared with Example 1, most of them are the same, except that the dispersant, polycarboxylate superplasticizer and additives are stirred in a water bath at 90°C during the preparation of the anti-adsorption mud-blocking water-reducing agent.

[0138] Comparative Example 8

[0139] Compared with Example 1, most of them are the same, except that the recycled fan blade powder used in the preparation of recycled coarse aggregate concrete is replaced with an equal mass of fly ash.

[0140] Comparative Example 9

[0141] Compared with Example 1, most of them are the same, except that the addition of recycled fan blade powder is omitted in the preparation of recycled coarse aggregate concrete.

[0142] Performance tests were conducted on the anti-adsorption mud-inhibiting water-reducing agent and the recycled coarse aggregate concrete prepared therefrom, including the following performance test methods:

[0143] (1) Organic carbon adsorption test method: Refer to the published invention patent (patent name: a method for preparing a mud-inhibiting water-reducing agent, patent publication number: CN 105622853 A). Weigh 1g of cement particles and mud particles (composed of clay particles, silt and dust particles) from the surface of recycled coarse aggregate, add them to 50ml of water-reducing agent solution prepared with pure water at a concentration of 1g / L, stir for 4min, centrifuge at high speed to obtain supernatant, take 2ml of supernatant and dilute it 20 times, and use a Toc total organic carbon analyzer to test the organic carbon content. Subtract the organic carbon content in the supernatant from the total amount of water-reducing agent added to get the amount of anti-adsorption mud-inhibiting water-reducing agent adsorbed by cement particles and recycled coarse aggregate mud particles. The effective adsorption ratio (η) is calculated as shown in the following formula (6). The adsorption values ​​of water-reducing agent on mud particles are shown in Table 2.

[0144]

[0145] Table 2 shows the adsorption properties of the water-reducing agents prepared in the examples and comparative examples on cement particles and clay particles on the surface of recycled coarse aggregate.

[0146]

[0147]

[0148] Note that Example 8 is missing from the above samples. The water-reducing agent used in Example 8 is the commercially available PCA-9 series polycarboxylate high-efficiency water-reducing agent produced by Jiangsu Subote. Examples 9, 8, and 9 are missing because the changes in the relevant raw materials during the experiment were unrelated to the preparation of the anti-adsorption mud-inhibiting water-reducing agent; therefore, the corresponding adsorption tests were omitted.

[0149] Comparing the above data reveals that the effective adsorption ratio of commercially available PCA-9 type polycarboxylate superplasticizer is only 0.20. This means that a considerable amount of polycarboxylate superplasticizer is adsorbed onto the mud particles on the surface of recycled aggregate, while less is adsorbed onto the surface of cement particles. As shown in Example 1, introducing fatty alcohol groups into the superplasticizer can promote the dispersion of cement particles, thereby enhancing the bonding between the superplasticizer and cement particles, resulting in a large amount of superplasticizer adsorbed onto the surface of cement particles. Introducing carboxyl groups into the superplasticizer can reduce the adsorption of high-valence metal ions on the superplasticizer from the mud particles on the surface of recycled aggregate, thereby improving the superplasticizer's anti-adsorption and mud-blocking properties. Storing fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder in glass bottles will cause oxidation-reduction reactions of carboxyl groups and fatty alcohols in the raw material due to the effects of light and oxygen, affecting the anti-adsorption performance of the raw material. Reducing the amount of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder (Example 5), replacing it (Comparative Example 5), or reducing it to 0 (Comparative Example 6) will result in a decrease or absence of the corresponding functional groups, leading to a decrease in the amount of water-reducing agent adsorbed on the surface of cement particles and an increase in the amount of mud particles adsorbed on the surface of recycled aggregate. This will be detrimental to the workability of recycled concrete. Furthermore, water bath conditions (Comparative Example 7) also affect the anti-adsorption performance of the water-reducing agent. At 90°C, the effective adsorption ratio of the water-reducing agent is only 24.15% of that in Example 1. This is mainly because the water bath temperature is too high, causing the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder and polycarboxylate water-reducing agent to lose activity during the preparation process, thus affecting the performance of the anti-adsorption and mud-blocking water-reducing agent. It is worth noting that in different examples and comparative examples, the higher the effective adsorption ratio, the better the anti-adsorption and mud-blocking characteristics of the water-reducing agent, and the stronger its binding ability to the surface of cement particles.

[0150] (2) Test methods for workability and mechanical properties: The workability was tested according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" and the 28-day compressive strength was tested according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are shown in Table 3.

[0151] Table 3. Test results of concrete workability and mechanical properties in the examples and comparative examples.

[0152]

[0153]

[0154] By comparing the above data, it was found that the water-reducing agent prepared in this invention can improve the mechanical properties (compressive strength) of concrete by promoting the dispersion of cement particles and enhancing cement hydration. Simultaneously, the introduction of carboxyl groups reduces the adsorption of the water-reducing agent by recycled aggregates, thereby improving the workability (slump and spread) of concrete. Except for the direct addition of commercially available PCA-9 series polycarboxylate high-efficiency water-reducing agents (Example 8), the water-reducing agents in this example all exhibit good workability and mechanical properties, and the fresh concrete mixtures prepared in the examples all have good fluidity and coating properties. However, the reduction (Example 9), replacement (Comparative Example 8), or reduction to 0 (Comparative Example 9) of recycled wind turbine blade powder will adversely affect the workability of concrete due to the reduced epoxy resin powder content, while the reduction of glass fiber powder results in limited improvement in the mechanical properties of concrete.

[0155] (3) Test method for chloride ion penetration resistance: The chloride ion penetration test of concrete was conducted according to ASTM C1202, "Standard Test Method for the Electrical Resistance of Concrete to Chloride Ion Penetration". The total amount of charge passing through is expressed in coulombs, which is used to characterize the chloride ion penetration resistance of the concrete specimens. The test was conducted using a concrete chloride ion permeameter from Shaoxing, Zhejiang. The calculation of the chloride ion diffusion coefficient was based on the published literature "Research Progress on Chloride Salt Erosion Resistance of Concrete in Marine Tidal Zone Environment Based on Similarity". The calculation results of the chloride ion diffusion coefficient of concrete within the 28-day erosion age of the specimens are shown in Table 4.

[0156] Table 4. Test results of the chloride ion attack resistance of concrete in the examples and comparative examples.

[0157]

[0158]

[0159] Note that Example 8 is missing from the above samples, while the water-reducing agent used in Example 8 is the commercially available PCA-9 series polycarboxylate high-efficiency water-reducing agent produced by Jiangsu Subote.

[0160] Comparing the above data reveals that the addition of commercially available PCA-9 polycarboxylate superplasticizer resulted in the highest electrical flux and chloride ion diffusion coefficient in the concrete test blocks, indicating poor resistance to chloride ion attack. In contrast, the superplasticizer prepared in this patent, by adding trimethoxysilane to introduce methoxysilane groups, gives the oxygen atoms in the superplasticizer lone pairs of electrons, allowing them to interact with anions via electron donor-acceptor interactions. This electronic effect helps reduce the reactivity of anions, thereby inhibiting the formation of chloride ions (Cl). -The transport of trimethoxysilane in concrete enhances its resistance to chloride ion attack. However, reducing the amount of trimethoxysilane solid powder in fatty alcohol polyoxyethylene ether nonanoate (Example 5), replacing it (Comparative Example 5), omitting it (Comparative Example 6), and omitting trimethoxysilane (Comparative Example 3) all reduce the proportion of methoxysilane groups in the water-reducing agent to varying degrees, resulting in higher electrical flux and chloride ion diffusion coefficients in the concrete. Furthermore, the anti-adsorption and anti-sludge properties of the prepared water-reducing agent also affect the chloride ion attack resistance of the concrete. Better anti-adsorption and anti-sludge properties of the water-reducing agent lead to better bonding with cement particles and a denser pore structure within the concrete, thereby improving its resistance to chloride ion attack.

[0161] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, characterized in that, Based on a total weight of 100 parts, it is composed of the following raw material components in parts by weight: fatty alcohol 20-40 parts, ethoxylation agent 10-20 parts, alkaline catalyst 5-10 parts, solvent 8-18 parts, azelaic acid 2-10 parts, trimethoxysilane 12-24 parts, and the remainder is deionized water. The fatty alcohol is one or more of hexanol, octanol, hexadecyl alcohol, or octadecanol; The ethoxylating agent is produced by stepwise addition polymerization of ethylene oxide with water or ethylene glycol, and its molecular weight is 2000-3000. The alkaline catalyst is one or both of sodium hydroxide or potassium hydroxide; The solvent is one or more of ethyl acetate, dimethylformamide, aminopropanol, or toluene.

2. The fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder according to claim 1, characterized in that, The fatty alcohol is composed of hexanol, octanol, and cetyl alcohol in a mass ratio of 1:1:

2.

3. The method for preparing the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Add solvent to a four-necked flask, then add fatty alcohol, ethoxylation agent, alkaline catalyst and deionized water in sequence, mix evenly to prepare a reaction solution, carry out polymerization reaction by heating and ultraviolet light irradiation, and stir evenly to obtain fatty alcohol polyoxyethylene ether. (2) Add azelaic acid to the container, stir magnetically, introduce nitrogen gas, heat to 80-120℃, and react at a constant temperature for 3-5 hours to obtain fatty alcohol polyoxyethylene ether nonanoate. (3) Add trimethoxysilane to the container, stir magnetically, introduce oxygen, heat to 70-85℃, and react at a constant temperature for 2-4 hours to obtain trimethoxysilane of fatty alcohol polyoxyethylene ether nonanoate. (4) After the reaction is complete, the product is cooled to room temperature and then transferred to a beaker. Next, it is placed in a vacuum oven and dried at 60°C. After drying, the obtained fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder is scraped out with a spatula and stored in a brown clamp sample bottle.

4. A water-reducing agent with anti-adsorption and mud-inhibiting properties suitable for recycled coarse aggregate concrete, characterized in that, Based on a total weight of 100 parts, it is composed of the following raw material components in parts by weight: 20-40 parts of fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder as described in claim 1 or 2, 4-10 parts of mud inhibitor, 2-8 parts of dispersant, 20-30 parts of polycarboxylate superplasticizer, 4-12 parts of additives, 5-7 parts of retarder, 2-10 parts of alkaline solution, and the remainder is deionized water.

5. The anti-adsorption and mud-inhibiting water-reducing agent for recycled coarse aggregate concrete according to claim 4, characterized in that, The mud-blocking agent is one or more of polyvinyl alcohol, polyethylene glycol diacrylate, or sulfonated lignin.

6. The anti-adsorption and mud-inhibiting water-reducing agent for recycled coarse aggregate concrete according to claim 4, characterized in that, The dispersant is sodium methylene bisnaphthalene sulfonate or methoxyethanolamine; The auxiliary agent is sodium methylpropene sulfonate.

7. The anti-adsorption and mud-inhibiting water-reducing agent for recycled coarse aggregate concrete according to claim 4, characterized in that, The retarder is one or both of sodium gluconate and potassium polyvinyl sulfate.

8. The anti-adsorption and mud-inhibiting water-reducing agent for recycled coarse aggregate concrete according to claim 4, characterized in that, The alkaline solution is an industrial-grade sodium hydroxide or potassium hydroxide solution with a mass fraction of 25%-30%.

9. The preparation method of an anti-adsorption and mud-inhibiting water-reducing agent suitable for recycled coarse aggregate concrete as described in claim 4, characterized in that, Includes the following steps: (1) Mix the fatty alcohol polyoxyethylene ether nonanoate trimethoxysilane solid powder, mud inhibitor and some deionized water thoroughly and completely dissolve them; (2) Continue to add dispersant, polycarboxylate superplasticizer and additives, and stir thoroughly in a water bath at 60-70℃ to ensure that the components are mixed evenly; (3) Then add alkaline solution and continue heating and stirring for 1-2 hours to adjust the pH of the system to 9.5-10.5; (4) Finally, add the retarder and the remaining deionized water, stir thoroughly and mix evenly, then cool and filter to remove impurities, thus obtaining the anti-adsorption mud-blocking water-reducing agent.

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