Elastic clip-type prestressed concrete square pile anchor adhesive and its preparation method

Abstract

This disclosure relates to the field of prestressed concrete square pile construction technology, and in particular to a spring-loaded prestressed concrete square pile anchoring adhesive and its preparation method; wherein, the concrete square pile anchoring adhesive is a polyurethane material containing a first nanoparticle and a second nanoparticle; the first nanoparticle is modified cerium dioxide nanoparticle, and the second nanoparticle is titanium dioxide nanoparticle.

Description

Technical Field

[0001] This disclosure relates to the field of prestressed concrete square pile construction technology, and in particular to a spring-loaded prestressed concrete square pile anchoring adhesive and its preparation method. Background Technology

[0002] Prestressed concrete square piles are frequently used in the construction of building pile foundations. The spring-loaded clamp connection method for prestressed concrete square piles is convenient and quick to install, making it widely used in pile foundation construction. During construction, the spring-loaded square pile is first driven into the soil, and then a prestressed concrete square pile with locking plates is hoisted and pressed into place. Because the locking plates protrude from the pile end, they are prone to displacement during pile transportation and handling, leading to inaccurate positioning when connected to the spring-loaded concrete pile in subsequent construction. Therefore, a fatigue-resistant, highly thixotropic adhesive could be developed to achieve rapid positioning and high-strength anchoring of the spring-loaded concrete pile. Summary of the Invention

[0003] This disclosure provides a spring-loaded prestressed concrete square pile anchoring adhesive and its preparation method to address the shortcomings of related technologies.

[0004] According to a first aspect of the present disclosure, a spring-loaded prestressed concrete square pile anchoring adhesive is provided, wherein the concrete square pile anchoring adhesive is a polyurethane material comprising a first nanoparticle and a second nanoparticle; wherein the first nanoparticle is modified cerium dioxide nanoparticle, and the second nanoparticle is titanium dioxide nanoparticle.

[0005] In one aspect of this disclosure, the modified cerium dioxide nanoparticles are obtained by modifying the prepared cerium dioxide nanoparticles. The preparation process of the cerium dioxide nanoparticles includes the following steps:

[0006] Step 1-1: Dissolve cerium carbonate in nitric acid solution to obtain an acidic solution containing cerium ions; dissolve ammonium carbonate in nitric acid solution to obtain a coprecipitant solution;

[0007] Step 1-2: Under stirring, the coprecipitant solution is added dropwise to the acid solution containing cerium ions, and then aged for 12-24 hours to obtain an aged mixture;

[0008] Steps 1-3: The aged mixture is heated at 150℃-200℃ for 1-2 hours, and then filtered, washed and dried to obtain precursor particles;

[0009] Steps 1-4: The precursor particles are calcined at 550℃-650℃ for 4-6 hours to obtain the cerium dioxide nanoparticles.

[0010] In one aspect of this disclosure, the modified cerium dioxide nanoparticles are prepared by reacting the prepared cerium dioxide nanoparticles with a silane coupling agent, the reaction process including the following steps:

[0011] Steps 1-5: Dry the cerium dioxide nanoparticles at 80℃-100℃ for 3-6 hours;

[0012] Steps 1-6: Dissolve the silane coupling agent γ-aminopropyltriethoxysilane in ethanol or acetone while stirring; then add the dried cerium dioxide nanoparticles, heat to 70℃-85℃ and react for 3-5 hours;

[0013] Steps 1-7: After the reaction is complete, the product is filtered, washed, and dried to obtain the modified cerium dioxide nanoparticles.

[0014] In one aspect of this disclosure, the titanium dioxide nanoparticles are a polystyrene-titanium dioxide composite material with a core-shell structure; the polystyrene-titanium dioxide composite material with a core-shell structure is prepared by the following steps:

[0015] Step 2-1: Add styrene and acrylic acid to an ethanol aqueous solution, then add potassium chloride, purge with nitrogen for protection, heat to 70℃-80℃ and hold for 20-60 minutes while stirring.

[0016] Step 2-2: Dissolve potassium persulfate in water to obtain an aqueous solution of potassium persulfate, then add it dropwise to the system in Step 2-1, and continue the reaction for 6-12 hours. After centrifugation, washing, and drying, carboxylated polystyrene microspheres are obtained.

[0017] Steps 2-3: Add the carboxylated polystyrene microspheres to ethanol while stirring, then add ammonia; then heat to 50℃-60℃ and keep warm for 20-60 min, then add an ethanol solution of tetrabutyl titanate, and continue the reaction for 3-6 h.

[0018] Steps 2-4: The reaction product is centrifuged, washed, and dried to obtain a polystyrene-titanium dioxide composite material with a core-shell structure.

[0019] In one aspect of the present disclosure, the mass ratio of the modified cerium dioxide nanoparticles to the core-shell structured polystyrene-titanium dioxide composite material is selected from 1:(3-5); preferably, the mass ratio of the modified cerium dioxide nanoparticles to the core-shell structured polystyrene-titanium dioxide composite material is selected from 1:(3-4); more preferably, the mass ratio of the modified cerium dioxide nanoparticles to the core-shell structured polystyrene-titanium dioxide composite material is selected from 1:(3.2-3.7).

[0020] According to a second aspect of the present disclosure, a method for preparing the aforementioned spring-loaded prestressed concrete square pile anchoring adhesive is provided, the method comprising the following steps:

[0021] Step 3-1: Add one of polyether polyol or polyester polyol to the reaction vessel, then heat to 60℃-80℃ and perform mechanical stirring and reflux.

[0022] Step 3-2: Provide diisocyanate and catalyst, dissolve the diisocyanate and catalyst in an organic solvent and add them to the reaction vessel, react for 2-4 hours to obtain polyurethane prepolymer;

[0023] Step 3-3: Provide a first chain extender and prepare a second chain extender. Dissolve the first and second chain extenders in an organic solvent to obtain a chain extender solution. Mix the chain extender solution with the polyurethane prepolymer and react at 60℃-80℃ for 2-3 hours. Then add the modified cerium dioxide nanoparticles and the polystyrene-titanium dioxide composite material with a core-shell structure, and continue the reaction for 30-85 minutes to obtain the spring-loaded prestressed concrete square pile anchoring adhesive.

[0024] In one aspect of the embodiments of this disclosure, in step 3-1, the polyether polyol is selected from polytetrahydrofuran ether diol, polypropylene glycol, or polyethylene glycol; the polyester polyol is selected from polycaprolactone diol, polyethylene adipate diol, polybutylene adipate diol, polypropylene adipate diol, polyhexyl adipate diol, or polybutylene phthalate diol.

[0025] In one aspect of the embodiments of this disclosure, specifically in step 3-1, polytetrahydrofuran ether diol is used as a reaction raw material.

[0026] In one aspect of the embodiments of this disclosure, in step 3-2, the diisocyanate is selected from toluene diisocyanate, dimethylbiphenyl diisocyanate, diphenylmethane diisocyanate, isophenyl dimethyl isocyanate, tetramethylphenyl dimethylene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, 1,4-cyclohexane dimethyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate.

[0027] In one aspect of the embodiments of this disclosure, specifically, in steps 3-2, toluene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, or 1,4-cyclohexanedimethyl diisocyanate is used as the reaction raw material.

[0028] In one aspect of the embodiments of this disclosure, in steps 3-2 and 3-3, the catalyst is selected from dibutyltin dilaurate, stannous octoate, triethylamine, triethylenediamine, or triethanolamine.

[0029] In one aspect of the embodiments of this disclosure, specifically in steps 3-2 and 3-3, dibutyltin dilaurate is used as a catalyst.

[0030] In one aspect of the embodiments of this disclosure, in step 3-3, the first chain extender is selected from 1,4-butanediol, diethylene glycol, trimethylolpropane, ethylene glycol, glycerol, or 1,4-cyclohexanediol.

[0031] In one aspect of the embodiments of this disclosure, specifically in step 3-3, the first chain extender is selected from 1,4-butanediol.

[0032] In one aspect of this disclosure, the second chain extender comprises a mixture of the following two compounds:

[0033]

[0034] In one aspect of this disclosure, the mass ratio of the first chain extender to the second chain extender is selected from 1:(0.15-0.35).

[0035] According to a third aspect of the present disclosure, the application of the aforementioned spring-loaded prestressed concrete square pile anchoring adhesive or the spring-loaded prestressed concrete square pile anchoring adhesive prepared according to the aforementioned method in the field of building engineering is provided.

[0036] In one aspect of this disclosure, the application is to use the anchoring adhesive to position and anchor a concrete pile with spring clips.

[0037] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0038] As can be seen from the above embodiments, the present disclosure has prepared a fatigue-resistant, highly thixotropic, and low-viscosity adhesive, which can achieve rapid positioning and high-strength anchoring of concrete piles with spring clips.

[0039] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Detailed Implementation

[0040] Exemplary embodiments will now be described in detail; the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The embodiments described herein are illustrative in nature and are used to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0042] For the sake of brevity, this article only discloses a few specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0043] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] In this description, unless otherwise stated, "above" and "below" include the stated number.

[0045] Unless otherwise stated, the terms used in this disclosure have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this disclosure can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this disclosure).

[0046] The term "about" is used to describe and indicate small variations. When used in conjunction with an event or situation, the term may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the term may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format herein. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only numerical values ​​explicitly specified as range limits but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0047] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0048] In this disclosure, the modified cerium dioxide nanoparticles can be prepared through the following steps:

[0049] Step 1-1: Dissolve 4.6g of cerium carbonate in 100mL of 69% nitric acid solution to obtain an acidic solution containing cerium ions; dissolve 1.42g of ammonium carbonate in 30mL of 69% nitric acid solution to obtain a coprecipitant solution;

[0050] Steps 1-2: Under stirring, the coprecipitant solution is added dropwise to the acid solution containing cerium ions, and then aged for 18 hours to obtain the aged mixture.

[0051] Steps 1-3: The aged mixture was heated at 190℃ for 1.5h, then filtered, washed three times with acetone, washed three times with deionized water, and dried at 60℃ for 6h to obtain precursor particles.

[0052] Steps 1-4: The precursor particles were calcined at 600℃ for 5.5h to obtain cerium dioxide nanoparticles;

[0053] Steps 1-5: Weigh 3g of the prepared cerium dioxide nanoparticles and dry them at 85℃ for 3h;

[0054] Steps 1-6: Dissolve 2g of silane coupling agent γ-aminopropyltriethoxysilane in 80mL of anhydrous ethanol, keep stirring at a stirring rate of 300r / min; then add dried cerium dioxide nanoparticles, heat to 80℃ and react for 4h.

[0055] Steps 1-7: After the reaction is complete, the product is filtered, washed three times with acetone, three times with deionized water, washed once with ethanol, and dried at 60℃ for 8 hours to obtain modified cerium dioxide nanoparticles.

[0056] In this disclosure, the polystyrene-titanium dioxide composite material with a core-shell structure can be prepared through the following steps:

[0057] Step 2-1: Add 6.8 mL of styrene and 8.3 mL of acrylic acid to an ethanol-water solution (mixed at a volume ratio of ethanol:water = 2:8), then add 1.75 g of potassium chloride, purge with nitrogen for protection, heat to 75 °C and hold for 45 min, while stirring at a rate of 300 r / min.

[0058] Step 2-2: Dissolve 1.42g of potassium persulfate in 20mL of water to obtain an aqueous solution of potassium persulfate, and then add it dropwise to the system in Step 2-1. Continue the reaction for 8h. After filtration, washing with acetone 3 times, washing with deionized water 3 times, washing with ethanol 2 times, and drying at 60℃ for 6h, carboxylated polystyrene microspheres are obtained.

[0059] Steps 2-3: Add carboxylated polystyrene microspheres to 80 mL of anhydrous ethanol and keep stirring at a rate of 300 r / min; then add 10 mL of 25% ammonia; then heat to 60 °C and keep warm for 45 min; then slowly add an ethanol solution of tetrabutyl titanate (obtained by dissolving 4 mL of tetrabutyl titanate in 20 mL of anhydrous ethanol) using a syringe pump for 1 h, and then continue the reaction for 5 h.

[0060] Steps 2-4: The reaction product was centrifuged at 4000 r / min for 5 min, washed 3 times with acetone, 3 times with deionized water, 3 times with ethanol, washed 3 times with deionized water again, and dried at 60℃ for 12 h to obtain a polystyrene-titanium dioxide composite material with a core-shell structure.

[0061] In this disclosure, the reaction formula for carboxylated polystyrene microspheres is as follows:

[0062]

[0063] In this disclosure, compounds A-1 and A-2 are prepared by the following steps:

[0064]

[0065] Specifically, 7.68 g of n-butylaniline and 11.5 mL of 37% hydrochloric acid were added to a 250 mL three-necked reaction flask, followed by 120 mL of water. The mixture was stirred until homogeneous, and then cooled to approximately 4°C using ice water. 3.48 g of sodium nitrite was added in multiple batches. The reaction was maintained at 0°C-5°C for 3 hours. After the reaction, a small amount of aminosulfonic acid was used to eliminate the remaining nitrite. Then, 9.69 g of 2,5-diaminobenzenesulfonic acid and 9.42 g of sodium carbonate were added directly to the reaction solution. The temperature was adjusted to approximately 10°C, and the reaction continued until the diazonium salt reaction was complete. The filtrate was then collected by filtration. After extraction, separation, and purification, two compounds were detected in the product: compound A-1 (71%) and compound A-2 (29%).

[0066] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention were obtained through conventional commercial means. Unless otherwise specified, all contents mentioned below are mass contents. Unless otherwise specified, it is understood that the process was carried out at room temperature.

[0067] Examples and Comparative Examples

[0068] Example 1:

[0069] Example 1 includes the following steps:

[0070] 1. Preparation of modified cerium dioxide nanoparticles:

[0071] 4.6 g of cerium carbonate was dissolved in 100 mL of 69% nitric acid solution to obtain an acid solution containing cerium ions; 1.42 g of ammonium carbonate was dissolved in 30 mL of 69% nitric acid solution to obtain a coprecipitant solution; the coprecipitant solution was added dropwise to the acid solution containing cerium ions under stirring, and then aged for 18 h to obtain an aged mixture.

[0072] The aged mixture was heated at 190℃ for 1.5h, then filtered, washed three times with acetone, washed three times with deionized water, and dried at 60℃ for 6h to obtain precursor particles; the precursor particles were calcined at 600℃ for 5.5h to obtain cerium dioxide nanoparticles.

[0073] Weigh 3g of the prepared cerium dioxide nanoparticles and dry them at 85℃ for 3h; dissolve 2g of silane coupling agent γ-aminopropyltriethoxysilane in 80mL of anhydrous ethanol and keep stirring at a stirring rate of 300r / min; then add the dried cerium dioxide nanoparticles, heat to 80℃ and react for 4h; after the reaction, filter the product, wash it 3 times with acetone, 3 times with deionized water, wash it once with ethanol, and dry it at 60℃ for 8h to obtain modified cerium dioxide nanoparticles.

[0074] 2. Preparation of polystyrene-titanium dioxide composite materials with core-shell structure:

[0075] 6.8 mL of styrene and 8.3 mL of acrylic acid were added to an ethanol-water solution (mixed at a volume ratio of ethanol:water = 2:8), followed by the addition of 1.75 g of potassium chloride. Nitrogen gas was introduced for protection, and the mixture was heated to 75 °C and held at that temperature for 45 min while maintaining a stirring rate of 300 r / min. 1.42 g of potassium persulfate was dissolved in 20 mL of water to obtain an aqueous solution of potassium persulfate, which was then added dropwise to the system from step 2-1. The reaction was continued for 8 h. After filtration, washing three times with acetone, three times with deionized water, and twice with ethanol, the mixture was dried at 60 °C for 6 h to obtain carboxylated polystyrene microspheres.

[0076] Carboxylated polystyrene microspheres were added to 80 mL of anhydrous ethanol and stirred at a rate of 300 rpm. Then, 10 mL of 25% ammonia was added. The temperature was then raised to 60 °C and held for 45 min. Then, an ethanol solution of tetrabutyl titanate (obtained by dissolving 4 mL of tetrabutyl titanate in 20 mL of anhydrous ethanol) was slowly added using a syringe pump over a period of 1 h. The reaction was then continued for 5 h. The product was centrifuged at 4000 rpm for 5 min, washed three times with acetone, three times with deionized water, three times with ethanol, and three more times with deionized water. The product was then dried at 60 °C for 12 h to obtain a polystyrene-titanium dioxide composite material with a core-shell structure.

[0077] 3. Preparation of the second chain extender:

[0078] 7.68 g of n-butylaniline and 11.5 mL of 37% hydrochloric acid were added to a 250 mL three-necked reaction flask, followed by 120 mL of water. The mixture was stirred until homogeneous, and then cooled to approximately 4 °C using ice water. 3.48 g of sodium nitrite was added in multiple batches. The reaction was maintained at 0 °C-5 °C for 3 hours. After the reaction, a small amount of aminosulfonic acid was used to eliminate the remaining nitrite. Then, 9.69 g of 2,5-diaminobenzenesulfonic acid and 9.42 g of sodium carbonate were added directly to the reaction solution. The temperature was adjusted to approximately 10 °C, and the reaction continued until the diazonium salt reaction was complete. The filtrate was then collected and purified by extraction to obtain the second chain extender. Analysis revealed two compounds in the second chain extender: compound A-1 (71%) and compound A-2 (29%).

[0079] The above process can be repeated multiple times to prepare sufficient amounts of the second chain extender, the core-shell structured polystyrene-titanium dioxide composite material, and the modified cerium dioxide nanoparticles for use in the following reactions.

[0080] 4. Preparation of anchoring adhesive:

[0081] 100 parts by weight of polytetrahydrofuran ether diol (specifically PTMG 1000) were added to a reaction vessel, and the mixture was heated to 70°C and mechanically stirred and refluxed. 50 parts by weight of toluene diisocyanate and 0.35 parts by weight of the catalyst dibutyltin dilaurate were provided. Toluene diisocyanate and dibutyltin dilaurate were dissolved in DMF and added to the reaction vessel. The reaction was carried out for 3 hours to obtain a polyurethane prepolymer. 60 parts by weight of the first chain extender 1,4-butanediol and 15 parts by weight of the prepared second chain extender were provided. The first and second chain extenders were dissolved in DMF to obtain a chain extender solution. The chain extender solution was mixed with the polyurethane prepolymer and reacted at 70°C for 3 hours. Then, 2 parts by weight of modified cerium dioxide nanoparticles and 7 parts by weight of a core-shell structured polystyrene-titanium dioxide composite material were added, and the reaction was continued for 45 minutes to obtain the anchoring adhesive of Example 1.

[0082] Comparative Example 1:

[0083] Comparative Example 1 includes the following steps:

[0084] 1. Preparation of modified cerium dioxide nanoparticles:

[0085] 4.6 g of cerium carbonate was dissolved in 100 mL of 69% nitric acid solution to obtain an acid solution containing cerium ions; 1.42 g of ammonium carbonate was dissolved in 30 mL of 69% nitric acid solution to obtain a coprecipitant solution; the coprecipitant solution was added dropwise to the acid solution containing cerium ions under stirring, and then aged for 18 h to obtain an aged mixture.

[0086] The aged mixture was heated at 190℃ for 1.5h, then filtered, washed three times with acetone, washed three times with deionized water, and dried at 60℃ for 6h to obtain precursor particles; the precursor particles were calcined at 600℃ for 5.5h to obtain cerium dioxide nanoparticles.

[0087] Weigh 3g of the prepared cerium dioxide nanoparticles and dry them at 85℃ for 3h; dissolve 2g of silane coupling agent γ-aminopropyltriethoxysilane in 80mL of anhydrous ethanol and keep stirring at a stirring rate of 300r / min; then add the dried cerium dioxide nanoparticles, heat to 80℃ and react for 4h; after the reaction, filter the product, wash it 3 times with acetone, 3 times with deionized water, wash it once with ethanol, and dry it at 60℃ for 8h to obtain modified cerium dioxide nanoparticles.

[0088] 2. Preparation of polystyrene-silica composite materials with core-shell structure:

[0089] 6.8 mL of styrene and 8.3 mL of acrylic acid were added to an ethanol-water solution (mixed at a volume ratio of ethanol:water = 2:8), followed by the addition of 1.75 g of potassium chloride. Nitrogen gas was introduced for protection, and the mixture was heated to 75 °C and held at that temperature for 45 min while maintaining a stirring rate of 300 r / min. 1.42 g of potassium persulfate was dissolved in 20 mL of water to obtain an aqueous solution of potassium persulfate, which was then added dropwise to the system from step 2-1. The reaction was continued for 8 h. After filtration, washing three times with acetone, three times with deionized water, and twice with ethanol, the mixture was dried at 60 °C for 6 h to obtain carboxylated polystyrene microspheres.

[0090] Carboxylated polystyrene microspheres were added to 80 mL of anhydrous ethanol and stirred at a rate of 300 r / min. Then, 10 mL of 25% ammonia was added. The temperature was then raised to 60 °C and held for 45 min. Then, an ethanol solution of tetraethoxysilane (obtained by dissolving 4 mL of tetraethoxysilane in 20 mL of anhydrous ethanol) was slowly added using a syringe pump over a period of 1 h. The reaction was continued for 5 h. The product was then centrifuged at 4000 r / min for 5 min, washed three times with acetone, three times with deionized water, three times with ethanol, and three more times with deionized water. Finally, it was dried at 60 °C for 12 h to obtain a polystyrene-silica composite material with a core-shell structure.

[0091] 3. Preparation of the second chain extender:

[0092] 7.68 g of n-butylaniline and 11.5 mL of 37% hydrochloric acid were added to a 250 mL three-necked reaction flask, followed by 120 mL of water. The mixture was stirred until homogeneous, and then cooled to approximately 4 °C using ice water. 3.48 g of sodium nitrite was added in multiple batches. The reaction was maintained at 0 °C-5 °C for 3 hours. After the reaction was complete, a small amount of aminosulfonic acid was used to eliminate the remaining nitrite. Then, 9.69 g of 2,5-diaminobenzenesulfonic acid and 9.42 g of sodium carbonate were added directly to the reaction solution. The temperature was adjusted to approximately 10 °C, and the reaction continued until the diazonium salt reaction was complete. The filtrate was then collected by filtration. After extraction, separation, and purification, the second chain extender was obtained.

[0093] 4. Preparation of anchoring adhesive:

[0094] 100 parts by weight of polytetrahydrofuran ether diol (specifically PTMG 1000) were added to a reaction vessel, and the mixture was heated to 70°C and mechanically stirred and refluxed. 50 parts by weight of toluene diisocyanate and 0.35 parts by weight of dibutyltin dilaurate catalyst were provided. Toluene diisocyanate and dibutyltin dilaurate were dissolved in DMF and added to the reaction vessel. The reaction was carried out for 3 hours to obtain a polyurethane prepolymer. 60 parts by weight of the first chain extender 1,4-butanediol and 15 parts by weight of the prepared second chain extender were provided. The first and second chain extenders were dissolved in DMF to obtain a chain extender solution. The chain extender solution was mixed with the polyurethane prepolymer and reacted at 70°C for 3 hours. Then, 2 parts by weight of modified cerium dioxide nanoparticles and 7 parts by weight of polystyrene-silica composite material with a core-shell structure were added, and the reaction was continued for 45 minutes to obtain the anchoring adhesive of Comparative Example 1.

[0095] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 prepared a polystyrene-silica composite material with a core-shell structure, rather than the polystyrene-titanium dioxide composite material with a core-shell structure of Example 1.

[0096] Example 2:

[0097] 1. Preparation of modified cerium dioxide nanoparticles:

[0098] 4.6 g of cerium carbonate was dissolved in 100 mL of 69% nitric acid solution to obtain an acid solution containing cerium ions; 1.42 g of ammonium carbonate was dissolved in 30 mL of 69% nitric acid solution to obtain a coprecipitant solution; the coprecipitant solution was added dropwise to the acid solution containing cerium ions under stirring, and then aged for 18 h to obtain an aged mixture.

[0099] The aged mixture was heated at 190℃ for 1.5h, then filtered, washed three times with acetone, washed three times with deionized water, and dried at 60℃ for 6h to obtain precursor particles; the precursor particles were calcined at 600℃ for 5.5h to obtain cerium dioxide nanoparticles.

[0100] Weigh 3g of the prepared cerium dioxide nanoparticles and dry them at 85℃ for 3h; dissolve 2g of silane coupling agent γ-aminopropyltriethoxysilane in 80mL of anhydrous ethanol and keep stirring at a stirring rate of 300r / min; then add the dried cerium dioxide nanoparticles, heat to 80℃ and react for 4h; after the reaction, filter the product, wash it 3 times with acetone, 3 times with deionized water, wash it once with ethanol, and dry it at 60℃ for 8h to obtain modified cerium dioxide nanoparticles.

[0101] 2. Preparation of the second chain extender:

[0102] 7.68 g of n-butylaniline and 11.5 mL of 37% hydrochloric acid were added to a 250 mL three-necked reaction flask, followed by 120 mL of water. The mixture was stirred until homogeneous, and then cooled to approximately 4 °C using ice water. 3.48 g of sodium nitrite was added in multiple batches. The reaction was maintained at 0 °C-5 °C for 3 hours. After the reaction was complete, a small amount of aminosulfonic acid was used to eliminate the remaining nitrite. Then, 9.69 g of 2,5-diaminobenzenesulfonic acid and 9.42 g of sodium carbonate were added directly to the reaction solution. The temperature was adjusted to approximately 10 °C, and the reaction continued until the diazonium salt reaction was complete. The filtrate was then collected by filtration. After extraction, separation, and purification, the second chain extender was obtained.

[0103] 3. Preparation of anchoring adhesive:

[0104] 100 parts by weight of polytetrahydrofuran ether diol (specifically PTMG 1000) were added to a reaction vessel, and the mixture was heated to 70°C and mechanically stirred and refluxed. 50 parts by weight of toluene diisocyanate and 0.35 parts by weight of dibutyltin dilaurate catalyst were provided. Toluene diisocyanate and dibutyltin dilaurate were dissolved in DMF and added to the reaction vessel. The reaction was carried out for 3 hours to obtain a polyurethane prepolymer. 60 parts by weight of the first chain extender 1,4-butanediol and 15 parts by weight of the prepared second chain extender were provided. The first and second chain extenders were dissolved in DMF to obtain a chain extender solution. The chain extender solution was mixed with the polyurethane prepolymer and reacted at 70°C for 3 hours. Then, 2 parts by weight of modified cerium dioxide nanoparticles and 7 parts by weight of commercially available titanium dioxide nanoparticles (D50 value of 200 nm) were added, and the reaction was continued for 45 minutes to obtain the anchoring adhesive of Example 2.

[0105] The difference between Example 2 and Example 1 is that Example 2 uses commercially available titanium dioxide nanoparticles with a D50 value of 200 nm instead of the core-shell structured polystyrene-titanium dioxide composite material in Example 1.

[0106] Example 3:

[0107] The steps in Example 3 are the same as those in Example 2, except that Example 3 uses titanium dioxide nanoparticles with a D50 value of 800 nm.

[0108] Comparative Example 2:

[0109] Comparative Example 2 includes the following steps:

[0110] 1. Preparation of modified cerium dioxide nanoparticles:

[0111] 4.6 g of cerium carbonate was dissolved in 100 mL of 69% nitric acid solution to obtain an acid solution containing cerium ions; 1.42 g of ammonium carbonate was dissolved in 30 mL of 69% nitric acid solution to obtain a coprecipitant solution; the coprecipitant solution was added dropwise to the acid solution containing cerium ions under stirring, and then aged for 18 h to obtain an aged mixture.

[0112] The aged mixture was heated at 190℃ for 1.5h, then filtered, washed three times with acetone, washed three times with deionized water, and dried at 60℃ for 6h to obtain precursor particles; the precursor particles were calcined at 600℃ for 5.5h to obtain cerium dioxide nanoparticles.

[0113] Weigh 3g of the prepared cerium dioxide nanoparticles and dry them at 85℃ for 3h; dissolve 2g of silane coupling agent γ-aminopropyltriethoxysilane in 80mL of anhydrous ethanol and keep stirring at a stirring rate of 300r / min; then add the dried cerium dioxide nanoparticles, heat to 80℃ and react for 4h; after the reaction, filter the product, wash it 3 times with acetone, 3 times with deionized water, wash it once with ethanol, and dry it at 60℃ for 8h to obtain modified cerium dioxide nanoparticles.

[0114] 2. Preparation of polystyrene-titanium dioxide composite materials with core-shell structure:

[0115] 6.8 mL of styrene and 8.3 mL of acrylic acid were added to an ethanol-water solution (mixed at a volume ratio of ethanol:water = 2:8), followed by the addition of 1.75 g of potassium chloride. Nitrogen gas was introduced for protection, and the mixture was heated to 75 °C and held at that temperature for 45 min while maintaining a stirring rate of 300 r / min. 1.42 g of potassium persulfate was dissolved in 20 mL of water to obtain an aqueous solution of potassium persulfate, which was then added dropwise to the system from step 2-1. The reaction was continued for 8 h. After filtration, washing three times with acetone, three times with deionized water, and twice with ethanol, the mixture was dried at 60 °C for 6 h to obtain carboxylated polystyrene microspheres.

[0116] Carboxylated polystyrene microspheres were added to 80 mL of anhydrous ethanol and stirred at a rate of 300 rpm. Then, 10 mL of 25% ammonia was added. The temperature was then raised to 60 °C and held for 45 min. Then, an ethanol solution of tetrabutyl titanate (obtained by dissolving 4 mL of tetrabutyl titanate in 20 mL of anhydrous ethanol) was slowly added using a syringe pump over a period of 1 h. The reaction was then continued for 5 h. The product was centrifuged at 4000 rpm for 5 min, washed three times with acetone, three times with deionized water, three times with ethanol, and three more times with deionized water. The product was then dried at 60 °C for 12 h to obtain a polystyrene-titanium dioxide composite material with a core-shell structure.

[0117] 3. Preparation of anchoring adhesive:

[0118] 100 parts by weight of polytetrahydrofuran ether diol (specifically PTMG 1000) were added to a reaction vessel, and the mixture was heated to 70°C and mechanically stirred and refluxed. 50 parts by weight of toluene diisocyanate and 0.35 parts by weight of the catalyst dibutyltin dilaurate were added to the reaction vessel in DMF and reacted for 3 hours to obtain a polyurethane prepolymer. 75 parts by weight of the first chain extender 1,4-butanediol were added to the reaction vessel in DMF to obtain a chain extender solution. The chain extender solution was mixed with the polyurethane prepolymer and reacted at 70°C for 3 hours. Then, 2 parts by weight of modified cerium dioxide nanoparticles and 7 parts by weight of a core-shell structured polystyrene-titanium dioxide composite material were added, and the reaction was continued for 45 minutes to obtain the anchoring adhesive of Comparative Example 2.

[0119] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not use a second chain extender.

[0120] Comparative Example 3:

[0121] Comparative Example 3 includes the following steps:

[0122] 1. Preparation of polystyrene-titanium dioxide composite materials with core-shell structure:

[0123] 6.8 mL of styrene and 8.3 mL of acrylic acid were added to an ethanol-water solution (mixed at a volume ratio of ethanol:water = 2:8), followed by the addition of 1.75 g of potassium chloride. Nitrogen gas was introduced for protection, and the mixture was heated to 75 °C and held at that temperature for 45 min while maintaining a stirring rate of 300 r / min. 1.42 g of potassium persulfate was dissolved in 20 mL of water to obtain an aqueous solution of potassium persulfate, which was then added dropwise to the system from step 2-1. The reaction was continued for 8 h. After filtration, washing three times with acetone, three times with deionized water, and twice with ethanol, the mixture was dried at 60 °C for 6 h to obtain carboxylated polystyrene microspheres.

[0124] Carboxylated polystyrene microspheres were added to 80 mL of anhydrous ethanol and stirred at a rate of 300 rpm. Then, 10 mL of 25% ammonia was added. The temperature was then raised to 60 °C and held for 45 min. Then, an ethanol solution of tetrabutyl titanate (obtained by dissolving 4 mL of tetrabutyl titanate in 20 mL of anhydrous ethanol) was slowly added using a syringe pump over a period of 1 h. The reaction was then continued for 5 h. The product was centrifuged at 4000 rpm for 5 min, washed three times with acetone, three times with deionized water, three times with ethanol, and three more times with deionized water. The product was then dried at 60 °C for 12 h to obtain a polystyrene-titanium dioxide composite material with a core-shell structure.

[0125] 2. Preparation of the second chain extender:

[0126] 7.68 g of n-butylaniline and 11.5 mL of 37% hydrochloric acid were added to a 250 mL three-necked reaction flask, followed by 120 mL of water. The mixture was stirred until homogeneous, and then cooled to approximately 4 °C using ice water. 3.48 g of sodium nitrite was added in multiple batches. The reaction was maintained at 0 °C-5 °C for 3 hours. After the reaction was complete, a small amount of aminosulfonic acid was used to eliminate the remaining nitrite. Then, 9.69 g of 2,5-diaminobenzenesulfonic acid and 9.42 g of sodium carbonate were added directly to the reaction solution. The temperature was adjusted to approximately 10 °C, and the reaction continued until the diazonium salt reaction was complete. The filtrate was then collected by filtration. After extraction, separation, and purification, the second chain extender was obtained.

[0127] 3. Preparation of anchoring adhesive:

[0128] 100 parts by weight of polytetrahydrofuran ether diol (specifically PTMG 1000) were added to a reaction vessel, and the mixture was heated to 70°C and mechanically stirred and refluxed. 50 parts by weight of toluene diisocyanate and 0.35 parts by weight of dibutyltin dilaurate catalyst were provided. Toluene diisocyanate and dibutyltin dilaurate were dissolved in DMF and added to the reaction vessel. The reaction was carried out for 3 hours to obtain a polyurethane prepolymer. 60 parts by weight of the first chain extender 1,4-butanediol and 15 parts by weight of the prepared second chain extender were provided. The first and second chain extenders were dissolved in DMF to obtain a chain extender solution. The chain extender solution was mixed with the polyurethane prepolymer and reacted at 70°C for 3 hours. Then, 2 parts by weight of commercially available silica nanoparticles (D50 value of 250 nm) and 7 parts by weight of a core-shell structured polystyrene-titanium dioxide composite material were added, and the reaction was continued for 45 minutes to obtain the anchoring adhesive of Comparative Example 3.

[0129] Performance testing:

[0130] The products of the examples and comparative examples were made into shear specimens and cured at room temperature (25°C) for 3 days. The shear strength of the specimens was then tested. The specimens were then placed outdoors for 15 days, and the shear strength of the specimens was tested. The test standard was GB / T7124-2008. The test results are shown in Table 1.

[0131] Table 1

[0132] Example Shear strength (MPa) after 3 days of curing Shear strength (MPa) after 15 days of outdoor exposure Example 1 18.5 18.0 Comparative Example 1 17.6 13.8 Example 2 17.8 16.9 Example 3 17.7 16.7 Comparative Example 2 13.2 12.7 Comparative Example 3 18.3 16.2

[0133] Comparing Example 1 and Comparative Example 2, it can be seen that the second chain extender prepared in this disclosure, after being introduced into the polyurethane chain segment, greatly improves the thixotropy of the material; this is because (1) compounds A-1 and A-2 contain tertiary amine groups, which can form hydrogen bonds or ion pairs with other polar groups in the polymer chain. This intermolecular interaction can significantly increase the yield stress of the material, thereby improving the thixotropy; furthermore, the tertiary amine group can form ion pairs with acidic groups (such as sulfonic acid groups, carboxylic acid groups, etc.) in the system, further enhancing the intermolecular interaction and improving the thixotropy of the material, while the compound Sulfonic acid groups are present in compounds A-1 and A-2, while the polystyrene-titanium dioxide composite material prepared in this disclosure contains carboxylic acid groups in polystyrene; thus greatly improving the thixotropic properties of the material (similarly, the performance of Examples 2 and 3, which do not use polystyrene-titanium dioxide composite materials, is also weaker than that of Example 1); (2) The sulfonic acid groups contained in compounds A-1 and A-2 can also enhance the intermolecular interaction, thereby improving the thixotropic properties; (3) The structures of compounds A-1 and A-2 form a network structure under low shear stress, which can increase the yield stress of the material.

[0134] Comparing Example 1 and Comparative Example 3, it can be seen that cerium dioxide can enhance the weather resistance of the material and has better UV resistance, so it can still maintain high thixotropy after being placed outdoors for a long time.

[0135] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A spring-loaded prestressed concrete square pile anchoring adhesive, characterized in that, The concrete square pile anchoring adhesive is a polyurethane material comprising a first nanoparticle and a second nanoparticle; wherein the first nanoparticle is modified cerium dioxide nanoparticle, and the second nanoparticle is titanium dioxide nanoparticle; wherein... The modified cerium dioxide nanoparticles are obtained by modifying the prepared cerium dioxide nanoparticles. The preparation process of the cerium dioxide nanoparticles includes the following steps: Step 1-1: Dissolve cerium carbonate in nitric acid solution to obtain an acidic solution containing cerium ions; dissolve ammonium carbonate in nitric acid solution to obtain a coprecipitant solution; Step 1-2: Under stirring, the coprecipitant solution is added dropwise to the acid solution containing cerium ions, and then aged for 12-24 hours to obtain an aged mixture; Steps 1-3: The aged mixture is heated at 150℃-200℃ for 1-2 hours, and then filtered, washed and dried to obtain precursor particles; Steps 1-4: The precursor particles are calcined at 550℃-650℃ for 4-6 hours to obtain the cerium dioxide nanoparticles. The modified cerium dioxide nanoparticles are prepared by reacting the prepared cerium dioxide nanoparticles with a silane coupling agent. The reaction process includes the following steps: Steps 1-5: Dry the cerium dioxide nanoparticles at 80℃-100℃ for 3-6 hours; Steps 1-6: Dissolve the silane coupling agent γ-aminopropyltriethoxysilane in ethanol or acetone while stirring; then add the dried cerium dioxide nanoparticles, heat to 70℃-85℃ and react for 3-5 hours; Steps 1-7: After the reaction is complete, the product is filtered, washed, and dried to obtain the modified cerium dioxide nanoparticles. The titanium dioxide nanoparticles are a polystyrene-titanium dioxide composite material with a core-shell structure; the polystyrene-titanium dioxide composite material with a core-shell structure is prepared through the following steps: Step 2-1: Add styrene and acrylic acid to an ethanol aqueous solution, then add potassium chloride, purge with nitrogen for protection, heat to 70℃-80℃ and hold for 20-60 minutes while stirring. Step 2-2: Dissolve potassium persulfate in water to obtain an aqueous solution of potassium persulfate, then add it dropwise to the system in Step 2-1, and continue the reaction for 6-12 hours. After centrifugation, washing, and drying, carboxylated polystyrene microspheres are obtained. Steps 2-3: Add the carboxylated polystyrene microspheres to ethanol while stirring, then add ammonia; then heat to 50℃-60℃ and keep warm for 20-60 min, then add an ethanol solution of tetrabutyl titanate, and continue the reaction for 3-6 h. Steps 2-4: The reaction product is centrifuged, washed, and dried to obtain a polystyrene-titanium dioxide composite material with a core-shell structure; The mass ratio of the modified cerium dioxide nanoparticles to the core-shell structured polystyrene-titanium dioxide composite material is selected from 1:(3-5).

2. A method for preparing the spring-loaded prestressed concrete square pile anchoring adhesive as described in claim 1, characterized in that, The method includes the following steps: Step 3-1: Add one of polyether polyol or polyester polyol to the reaction vessel, then heat to 60℃-80℃ and perform mechanical stirring and reflux. Step 3-2: Provide diisocyanate and catalyst, dissolve the diisocyanate and catalyst in an organic solvent and add them to the reaction vessel, react for 2-4 hours to obtain polyurethane prepolymer; Step 3-3: Provide a first chain extender and prepare a second chain extender. Dissolve the first and second chain extenders in an organic solvent to obtain a chain extender solution. Mix the chain extender solution with the polyurethane prepolymer and react at 60℃-80℃ for 2-3 hours. Then add the modified cerium dioxide nanoparticles and the polystyrene-titanium dioxide composite material with a core-shell structure, and continue the reaction for 30-85 minutes to obtain the spring-loaded prestressed concrete square pile anchoring adhesive.

3. The method according to claim 2, characterized in that, The method satisfies at least one of the following conditions: (1) In step 3-1, the polyether polyol is selected from polytetrahydrofuran ether diol, polypropylene glycol or polyethylene glycol; the polyester polyol is selected from polycaprolactone diol, polyethylene adipate diol, polybutylene adipate diol, polypropylene adipate diol, polyhexyl adipate diol or polybutylene phthalate diol; (2) In step 3-2, the diisocyanate is selected from toluene diisocyanate, dimethyl biphenyl diisocyanate, diphenylmethane diisocyanate, isophenyl dimethyl isocyanate, tetramethyl phenyl dimethylene diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, 1,4-cyclohexane dimethyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate; (3) In steps 3-2 and 3-3, the catalyst is selected from dibutyltin dilaurate, stannous octoate, triethylamine, triethylenediamine or triethanolamine; (4) In step 3-3, the first chain extender is selected from 1,4-butanediol, diethylene glycol, trimethylolpropane, ethylene glycol, glycerol or 1,4-cyclohexanediol.

4. The method according to claim 2, characterized in that, The second chain extender comprises a mixture of the following two compounds: 。 5. The method according to any one of claims 2-4, characterized in that, The mass ratio of the first chain extender to the second chain extender is selected from 1:(0.15-0.35).

6. The application of the spring-loaded prestressed concrete square pile anchoring adhesive according to claim 1, or the spring-loaded prestressed concrete square pile anchoring adhesive prepared according to any one of claims 2-5, in the field of building engineering.

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