Rare earth doped humic acid based retarder, preparation method and application in grouting material

Abstract

The invention discloses a rare earth doped humic acid-based retarder, a preparation method and application thereof in grouting materials, and belongs to the technical field of inorganic non-metal building materials. The invention discloses a rare earth doped humic acid-based retarder, which is prepared from the following raw materials in parts by weight: 35 to 50 parts of rare earth modified humic acid, 10 to 15 parts of amphiphilic phosphonate dispersing agent, 5 to 8 parts of magnesium phosphate corrosion inhibition reinforcing agent, 8 to 12 parts of nano silicon dioxide and 3 to 5 parts of function regulator. The loading capacity of rare earth oxide in the rare earth modified humic acid is 8-12wt%. The retarder provided by the invention realizes effective retarding through an innovative hydration inhibition mechanism, and has significant advantages in temperature response characteristics, hydrolysis resistance and diversified regulation performance. The effects are synergistic, so that the grouting agent is particularly suitable for grouting construction under severe conditions such as high temperature and the like, and a more stable, reliable and flexible solution is provided for engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic non-metallic building materials, and particularly relates to a rare earth-doped humic acid-based retarder, a preparation method and application of the retarder in grouting materials. Background Art

[0002] Post-tensioning technology plays a crucial role in large-scale projects such as modern buildings and bridges. Grouting material, the core material used to fill prestressed ducts, has a significant impact on the protection of prestressed tendons, the effective transfer of prestress, and the durability of the structure. As construction continues to expand into extreme environments, grouting operations in high-temperature conditions present significant challenges. Existing retarder technology and grouting material performance are no longer sufficient to meet these requirements.

[0003] In the field of retarder technology, traditional solutions have obvious limitations. For example, the N-hydroxyethyl acrylamide polymer retarder proposed in the patent with publication number CN111333760A completely fails due to thermal breakage of the molecular chain in a high-temperature environment above 45°C, and cannot meet the basic requirements of high-temperature construction for retarding stability. At the same time, as described in patent CN119798645A, although traditional retarders based on the HEDP-PEG system can achieve a retarding effect in the medium and low temperature range (<50°C), due to the lag in dynamic response, they cannot dynamically enhance the retarding effect under conditions of sudden temperature rise (such as sudden high temperature during construction). This results in excessive retarding of the slurry at low temperatures and uncontrollable setting time, while the retarding effect is lost at high temperatures, causing the risk of premature setting of the slurry, which seriously restricts the construction reliability in areas with high temperatures and large temperature differences.

[0004] In addition to the temperature sensitivity problem, the existing grouting materials have systematic shortcomings in comprehensive performance: (1) Insufficient anti-segregation: Traditional polycarboxylic acid water-reducing agents have poor dispersion stability in high water-cement ratio slurries, the slurries are prone to stratification and segregation, and the water seepage rate is too high, resulting in a decrease in the pore filling density and the formation of seepage channels; (2) Weak adaptability to low temperatures: The cement hydration rate drops sharply under low temperature conditions, resulting in slow early strength growth of the grouting materials, extending the construction period and increasing project costs; (3) Environmental protection and durability defects: Traditional expansive agents not only have environmental risks, but their high alkali content can also easily induce alkali-aggregate reactions, threatening structural safety; at the same time, after freeze-thaw cycles, the strength loss is obvious, and the drying shrinkage rate remains high, seriously affecting the long-term stability and service life of the structure.

[0005] In summary, the development of a new retarder and grouting material system that can stably play a retarding effect in a high-temperature environment and has excellent anti-segregation properties, low-temperature adaptability, environmental protection and durability has become the key to promoting the sustainable development of post-tensioning technology and is of great significance to improving project quality and safety. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a rare earth doped humic acid-based retarder that has both high temperature retarding stability and dynamic temperature adaptability, and can improve the retarder's anti-segregation, low temperature enhancement, environmental protection and durability.

[0007] A second object of the present invention is to provide a method for preparing the rare earth-doped humic acid-based retarder.

[0008] The third object of the present invention is to provide the use of the rare earth-doped humic acid-based retarder in grouting material.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] The first aspect of the present invention discloses a rare earth-doped humic acid-based retarder, the raw materials of which include the following substances in parts by weight: 35-50 parts of rare earth-modified humic acid, 10-15 parts of amphiphilic phosphonate dispersant, 5-8 parts of magnesium phosphate corrosion inhibitor enhancer, 8-12 parts of nano-silicon dioxide, and 3-5 parts of functional regulator;

[0011] The loading amount of the rare earth oxide in the rare earth modified humic acid is 8-12 wt %; the rare earth oxide is preferably one of lanthanum oxide, cerium oxide and yttrium oxide.

[0012] In some embodiments of the present invention, the preparation method of the rare earth modified humic acid includes the following steps: using an ion exchange method, soaking humic acid in a rare earth salt solution for a period of time, so that the carboxylic acid functional groups in the humic acid undergo ion exchange reaction with lanthanide ions to achieve the loading of rare earth elements on the humic acid, and then filtering, washing, and drying to obtain rare earth modified humic acid.

[0013] In the present invention, the introduction of rare earth elements makes the humic acid particles obtain special properties, and the Ca 2+ Site competitive adsorption occurs, reducing the amount of Ca involved in the hydration reaction 2+ The amount of cement hydration is increased, which delays the cement hydration process and achieves retarding by interacting with cement particles.

[0014] Preferably, the concentration of the rare earth salt solution is 0.2-0.5 mol / L.

[0015] The ratio of humic acid to rare earth salt is (5:1)-(15:1)

[0016] The reaction time is 1.5-3 hours, and the reaction temperature is 50-70°C.

[0017] In some embodiments of the present invention, the amphiphilic phosphonate dispersant has the structural formula C 12 H 25-O-PO(OH)-C6H4-SO3H. This "amphiphilic" structure enables directional adsorption at the solid-liquid interface, effectively reducing interfacial tension, thereby promoting the uniform dispersion of the retarder components in the grouting material and improving the retarder's stability and effectiveness.

[0018] In some embodiments of the present invention, the preparation method of the amphiphilic phosphonate dispersant comprises the following steps:

[0019] S1. The long-chain fatty alcohol is reacted with phosphorus oxychloride under a protective atmosphere by heating to form an intermediate phosphate monoester;

[0020] S2. Adding a modified monomer containing a hydrophilic group, polyethylene glycol monomethyl ether, and a catalyst to the reaction system for dehydration condensation reaction to generate an amphiphilic phosphonate dispersant.

[0021] Preferably, the long-chain fatty alcohol comprises stearyl alcohol;

[0022] Preferably, the molar ratio of long-chain fatty alcohol to phosphorus oxychloride is 1:0.8-1.5, preferably 1:1.2;

[0023] Preferably, in step S1, the reaction temperature is 80-90° C., and the reaction is carried out at a constant temperature for 4-6 hours;

[0024] Preferably, the average molecular weight of the modified monomer polyethylene glycol monomethyl ether containing a hydrophilic group is 400-600;

[0025] Preferably, the molar ratio of the modified monomer polyethylene glycol monomethyl ether to the intermediate is 1:1;

[0026] Preferably, the catalyst is toluenesulfonic acid, and its amount is 0.5-1% of the total reactant mass;

[0027] Preferably, in step S2, the dehydration condensation reaction is carried out at 110-120° C. for 3-5 hours;

[0028] Preferably, in step S2, after the reaction is completed, the mixture is cooled, the pH is adjusted to neutral, the by-products are removed by filtration, and the final product is vacuum dried to obtain an amphiphilic phosphonate dispersant.

[0029] In some embodiments of the present invention, the particle size D50 of the magnesium phosphate corrosion inhibitor is ≤ 5 μm; it can enhance the durability of the grouting material and assist in the retarding process.

[0030] In some embodiments of the present invention, the specific surface area of ​​nano-silicon dioxide is ≥200m 2 / g. The larger specific surface area provides a good load-bearing and dispersion environment for other components, promoting the contact reaction between the retarder and cement particles.

[0031] In some embodiments of the present invention, the functional regulator includes at least one of nitrogen-containing borate complexes, aminosulfonates, organic amines, and polyhydroxycarboxylates.

[0032] Nitrogen-containing borate complexes interact with cement hydration products through their special molecular structure, regulating the cement hydration process and optimizing the retarder performance.

[0033] Sulfamates, such as sodium sulfamate, contain active groups such as amino and sulfonic acid groups. They can complex with ions on the surface of cement particles, altering the charge distribution and potential on the surface, thereby regulating the hydration process. Furthermore, the hydrophilic and hydrophobic groups in their molecular structure can influence the surface tension of the cement paste, helping to improve the fluidity and water retention of the grout.

[0034] Organic amines, such as triethanolamine, react with calcium hydroxide produced during cement hydration to form a complex, slowing the crystallization of calcium hydroxide and thereby regulating the hydration rate of cement. They also form an adsorption layer on the surface of cement particles, acting as a dispersion agent and helping to improve the uniformity and stability of the grout.

[0035] Polyhydroxycarboxylates, such as sodium citrate, have multiple hydroxyl and carboxyl groups. These functional groups can complex with metal ions in cement, reducing the concentration of free metal ions in the solution and inhibiting the early hydration reaction of cement. Furthermore, their adsorption on the surface of cement particles can alter the interaction between the particles, affecting the performance of the grouting material.

[0036] The second aspect of the present invention further discloses a method for preparing the rare earth-doped humic acid-based retarder, which comprises the following steps:

[0037] Step 1. Prepare the raw materials in proportion;

[0038] Step 2. Self-assemble the rare earth modified humic acid and the amphiphilic phosphonate dispersant in a liquid phase at a mass ratio of 1:0.2-0.5, pH = 6-8, temperature 40-60°C, and time 1-3 hours to form a sustained-release unit with a core-shell structure;

[0039] Preferably, the liquid phase is a water-ethanol mixture, and the volume ratio of water to ethanol is 8 to 10:1, more preferably 9:1;

[0040] Preferably, the mass volume ratio of the rare earth modified humic acid to the water-ethanol mixture is 35-50g:500-700ml.

[0041] Step 3. Place the slow-release unit, magnesium phosphate corrosion inhibitor, nano-silica and functional regulator obtained in step 2 into a mixing device for dry mixing to ensure that the components are preliminarily mixed evenly, and then grind and mix to prepare a finished retarder.

[0042] In some embodiments of the present invention, in step 3, the ball milling time is 2-4 hours and the rotation speed is 300-500 rpm.

[0043] The third aspect of the present invention discloses the use of the rare earth-doped humic acid-based retarder in grouting material.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The invention is scientifically designed and ingeniously conceived. The retarder of the invention has excellent temperature response characteristics, unique hydration inhibition mechanism, reliable anti-hydrolysis performance and flexible and diversified adjustment performance.

[0046] The retarder of the present invention has excellent temperature response characteristics. Under a high temperature environment of 50°C, the retarder of the present invention can still maintain a retarding time of 28-35 hours for the grouting material, which is more than double the maximum time of 15 hours of conventional products, significantly improving the controllability of construction under high temperature environments. In addition, the retarder time of the present invention shows a nonlinear and stable response to temperature changes, and the temperature coefficient α is ≤0.03. This means that when encountering temperature fluctuations within a certain range in actual construction, the retarding time will not change drastically, thereby providing a stable and reliable setting time guarantee for high-temperature grouting operations.

[0047] The hydration inhibition mechanism of the retarder of the present invention lays the foundation for its retarding effect. This mechanism is achieved through the synergistic effect of the special component A ion and the B macromolecule. The A ion, with its larger ionic radius and higher charge density, preferentially binds to the Ca ions on the surface of cement particles. 2+ Site competitive adsorption occurs, effectively reducing the amount of Ca involved in the initial hydration reaction 2+ At the same time, macromolecule B, through its functional groups, physically adsorbs and chemically interacts with the surface of cement particles, forming a three-dimensional steric barrier. This steric barrier acts as a physical barrier, effectively hindering direct contact and further reaction between cement particles. These two mechanisms complement each other, effectively slowing the cement hydration process by reducing key reactants and creating a physical barrier.

[0048] Furthermore, the hydrolysis resistance of the retarder of the present invention further enhances its high-temperature stability. The phosphonate groups in the amphiphilic phosphonate dispersant are acidic. When hydration at high temperatures produces a large amount of OH-, causing the system pH to rise, the phosphonate groups react with the OH- to neutralize the acid, stabilizing the pH in the range of 11.5-12.0. Conventional systems can reach a pH of 12.8 under these conditions. By stabilizing the system pH, the retarder of the present invention effectively prevents its components from hydrolyzing and failing due to high pH, ​​ensuring continued stable performance at high temperatures.

[0049] Finally, the diverse adjustable properties endow the retarder of this invention with broad engineering adaptability. Different functional modifiers allow precise adjustment of retarder performance across multiple dimensions, including setting time, early strength, and fluidity. This allows it to meet the long-term retarding requirements of high-temperature environments, such as long-span bridges, while also accommodating the rapid construction of smaller components. Flexible formulation adjustments enable dynamic response to diverse construction conditions and engineering requirements, significantly expanding its application potential.

[0050] In summary, the retarder of this invention achieves effective set retardation through an innovative hydration inhibition mechanism, and offers significant advantages in temperature responsiveness, hydrolysis resistance, and diverse adjustability. These synergistic effects make it particularly suitable for grouting operations under harsh conditions such as high temperatures, providing a more stable, reliable, and flexible solution for projects. DETAILED DESCRIPTION

[0051] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0052] The magnesium phosphate used in the embodiments of the present invention is a commercially available product with a particle size D50≤5 μm.

[0053] The nano-silica carrier described in the embodiment of the present invention is a commercially available product with a specific surface area of ​​≥200m 2 / g.

[0054] Unless otherwise specified, the parts described in the embodiments of the present invention are parts by mass.

[0055] Example 1

[0056] This embodiment discloses a method for preparing the rare earth-doped humic acid-based retarder of the present invention. The raw materials of the rare earth-doped humic acid-based retarder of this embodiment are as follows:

[0057] 45 parts of rare earth modified humic acid, 12 parts of amphiphilic phosphonate dispersant, 6 parts of magnesium phosphate, 10 parts of nano-silicon dioxide, and 4 parts of nitrogen-containing borate complex.

[0058] The rare earth-modified humic acid is prepared by immersing 10g of humic acid in 100ml of a 0.3mol / L lanthanum nitrate solution and stirring at 65°C for 3 hours to allow for a complete ion exchange reaction between the lanthanum ions and the carboxylic acid functional groups in the humic acid. The solution is then filtered, washed, and dried to obtain the rare earth-modified humic acid. In this example, the rare earth-modified humic acid has a La2O3 loading of 10wt%.

[0059] The preparation method of the amphiphilic phosphonate dispersant comprises the following steps: adding octadecyl alcohol and phosphorus oxychloride in a molar ratio of 1:1.2 into a reaction kettle, gradually heating the reaction kettle to 80°C under nitrogen protection, and reacting at this temperature for 6 hours to generate an intermediate phosphate monoester; subsequently adding polyethylene glycol monomethyl ether (average molecular weight of 400-600) as a modified monomer containing a hydrophilic group, mixing the mixture with the intermediate in an esterification reaction molar ratio of 1:1, adding p-toluenesulfonic acid as a catalyst (in an amount of 1% of the total reactants), heating the mixture to 110°C for dehydration condensation reaction for 5 hours, adjusting the pH to neutral after cooling, filtering to remove by-products, and vacuum drying the final product to obtain the amphiphilic phosphonate dispersant.

[0060] The preparation method of the rare earth-doped humic acid-based retarder of this embodiment is as follows: 45 g of the rare earth-modified humic acid and 12 g of an amphiphilic phosphonate dispersant (mass ratio 1:0.3) are added to 500 mL of a water-ethanol mixture (volume ratio 9:1), the pH is adjusted to 7, and the mixture is stirred at 50°C for 2 hours to produce a core-shell sustained-release unit. The resulting core-shell sustained-release unit is then dry-mixed with the above-mentioned raw materials in a mixing apparatus for 40 minutes to achieve preliminary uniform mixing. The components are then further ground and mixed using a vibratory ball mill for 3 hours at 300 rpm to produce the finished retarder.

[0061] Example 2

[0062] This embodiment discloses a method for preparing the rare earth-doped humic acid-based retarder of the present invention. The raw materials of the rare earth-doped humic acid-based retarder of this embodiment are as follows:

[0063] 35 parts of rare earth modified humic acid, 15 parts of amphiphilic phosphonate dispersant, 7 parts of magnesium phosphate, 12 parts of nano silicon dioxide, and 5 parts of sodium aminosulfonate.

[0064] The rare earth-modified humic acid is prepared by immersing 10g of humic acid in 100ml of a 0.2mol / L cerium nitrate solution and stirring at 65°C for 2 hours to allow for a complete ion exchange reaction between the cerium ions and the carboxylic acid functional groups in the humic acid. The solution is then filtered, washed, and dried to obtain the rare earth-modified humic acid. In this example, the rare earth-modified humic acid has a Ce(NO3)3 loading of 8wt%.

[0065] The preparation method of the amphiphilic phosphonate dispersant comprises the following steps: adding octadecyl alcohol and phosphorus oxychloride in a molar ratio of 1:1.0 into a reaction kettle, gradually heating the mixture to 90° C. under nitrogen protection, and reacting at this temperature for 4 hours to generate an intermediate phosphate monoester; subsequently adding polyethylene glycol monomethyl ether (average molecular weight of 400-600) as a modified monomer containing a hydrophilic group, mixing the mixture with the intermediate in an esterification reaction molar ratio of 1:1, adding p-toluenesulfonic acid as a catalyst (in an amount of 0.5% of the total reactants), heating the mixture to 120° C. and carrying out a dehydration condensation reaction for 3 hours, adjusting the pH to neutral after cooling, filtering to remove byproducts, and vacuum drying the final product to obtain the amphiphilic phosphonate dispersant.

[0066] The preparation method of the rare earth-doped humic acid-based retarder of this embodiment is as follows: 35 g of the rare earth-modified humic acid and 15 g of an amphiphilic phosphonate dispersant (mass ratio 1:0.4) are added to 600 mL of a water-ethanol mixture (volume ratio 9:1), the pH is adjusted to 7, and the mixture is stirred at 55°C for 2.5 hours to produce a core-shell sustained-release unit. The resulting core-shell sustained-release unit is then placed in a mixing apparatus and dry-mixed with the above-mentioned raw materials for 30 minutes to achieve preliminary uniform mixing. The mixture is then further ground and mixed using a vibratory ball mill for 3.5 hours at 350 rpm to produce the finished retarder.

[0067] Example 3

[0068] This embodiment discloses a method for preparing the rare earth-doped humic acid-based retarder of the present invention. The raw materials of the rare earth-doped humic acid-based retarder of this embodiment are as follows:

[0069] 50 parts of rare earth modified humic acid, 10 parts of amphiphilic phosphonate dispersant, 5 parts of magnesium phosphate, 8 parts of nano silicon dioxide, and 4 parts of triethanolamine.

[0070] The rare earth-modified humic acid is prepared by immersing 10g of humic acid in 100ml of a 0.4mol / L yttrium chloride solution and stirring at 50°C for 3 hours to allow for a complete ion exchange reaction between the yttrium ions and the carboxylic acid functional groups in the humic acid. The solution is then filtered, washed, and dried to obtain the rare earth-modified humic acid. In this example, the Y2O3 loading in the rare earth-modified humic acid is 12wt%.

[0071] The preparation method of the amphiphilic phosphonate dispersant comprises the following steps: adding octadecyl alcohol and phosphorus oxychloride in a molar ratio of 1:1.5 into a reaction kettle, gradually heating the mixture to 90°C under nitrogen protection, and reacting at this temperature for 6 hours to generate an intermediate phosphate monoester; subsequently adding polyethylene glycol monomethyl ether (average molecular weight of 400-600) as a modified monomer containing a hydrophilic group, mixing the mixture with the intermediate in an esterification reaction molar ratio of 1:1, adding p-toluenesulfonic acid as a catalyst (in an amount of 0.5% of the total reactants), heating the mixture to 120°C for dehydration condensation reaction for 4 hours, adjusting the pH to neutral after cooling, filtering to remove by-products, and vacuum drying the final product to obtain the amphiphilic phosphonate dispersant.

[0072] The preparation method of the rare earth-doped humic acid-based retarder of this embodiment is as follows: 50 g of the above-mentioned rare earth-modified humic acid and 10 g of an amphiphilic phosphonate dispersant (mass ratio of 1:0.2) are added to 700 mL of a water-ethanol mixture (volume ratio of 9:1), the pH is adjusted to 7, and the mixture is stirred at 60°C for 3 hours to produce a core-shell sustained-release unit. The resulting core-shell sustained-release unit is then dry-mixed with the above-mentioned raw materials in a mixing apparatus for 40 minutes to achieve preliminary uniform mixing. The components are then further ground and mixed using a vibratory ball mill for 4 hours at 400 rpm to produce the finished retarder.

[0073] Example 4

[0074] This embodiment discloses a method for preparing the rare earth-doped humic acid-based retarder of the present invention. The raw materials of the rare earth-doped humic acid-based retarder of this embodiment are as follows:

[0075] 40 parts of rare earth modified humic acid, 14 parts of amphiphilic phosphonate dispersant, 8 parts of magnesium phosphate, 11 parts of nano silicon dioxide, and 3 parts of sodium citrate.

[0076] The rare earth-modified humic acid is prepared by immersing 10g of humic acid in 100ml of a 0.3mol / L lanthanum nitrate solution and stirring at 70°C for 1.5 hours to allow for a complete ion exchange reaction between the lanthanum ions and the carboxylic acid functional groups in the humic acid. The solution is then filtered, washed, and dried to obtain the rare earth-modified humic acid. In this example, the rare earth-modified humic acid has a La2O3 loading of 10wt%.

[0077] The preparation method of the amphiphilic phosphonate dispersant comprises the following steps: adding octadecyl alcohol and phosphorus oxychloride in a molar ratio of 1:1.2 into a reaction kettle, gradually heating the reaction kettle to 85°C under nitrogen protection, and reacting at this temperature for 6 hours to generate an intermediate phosphate monoester; subsequently adding polyethylene glycol monomethyl ether (average molecular weight of 400-600) as a modified monomer containing a hydrophilic group, mixing the mixture with the intermediate in an esterification reaction molar ratio of 1:1, adding p-toluenesulfonic acid as a catalyst (in an amount of 0.5% of the total reactants), heating the mixture to 110°C for dehydration condensation reaction for 4 hours, adjusting the pH to neutral after cooling, filtering to remove by-products, and vacuum drying the final product to obtain the amphiphilic phosphonate dispersant.

[0078] The preparation method of the rare earth-doped humic acid-based retarder of this embodiment is as follows: 40g of the above-mentioned rare earth-modified humic acid and 14g of an amphiphilic phosphonate dispersant (mass ratio of 1:0.35) are added to 500mL of a water-ethanol mixture (volume ratio of 9:1), the pH is adjusted to 7, and the mixture is stirred at 65°C for 4 hours to produce a core-shell sustained-release unit. The resulting core-shell sustained-release unit is then placed in a mixing apparatus and dry-mixed with the above-mentioned raw materials for 50 minutes to achieve preliminary uniform mixing. The mixture is then further ground and mixed using a vibratory ball mill for 5 hours at 450 rpm to produce the finished retarder.

[0079] Comparative Example 1

[0080] Compared with Example 1, this comparative example is different in that "rare earth modified humic acid" is replaced by "humic acid", and the other conditions are the same.

[0081] Comparative Example 2

[0082] Compared with Example 1, this comparative example is different in that the "amphiphilic phosphonate dispersant" is replaced by sodium lignin sulfonate, and the other conditions are the same.

[0083] Comparative Example 3

[0084] The commercially available retarder is SETTER D-300 retarder produced by Electrochemical Inorganic Materials (Tianjin) Co., Ltd.

[0085] Test Example 1

[0086] The retarders of Examples 1-4 and Comparative Examples 1-3 were added to the grouting materials respectively, and the performance of the grouting materials was tested.

[0087] The composition of the press slurry is as follows (parts by mass):

[0088] Ordinary Portland cement: 500 parts;

[0089] Quartz sand (fineness modulus 2.6): 300 parts;

[0090] Polycarboxylic acid water reducer: 3 parts;

[0091] Defoaming agent (silicone type): 1 part;

[0092] Cellulose ether: 2 parts;

[0093] Water: 180 parts.

[0094] Retarder (the amount added is adjusted according to the experimental design, as described below)

[0095] The amount of retarder added is:

[0096] For Examples 1-4 and Comparative Examples 1-3, the retarder was added at a rate of 0.5%-2% by weight of the cement in the slurry (the specific amount was adjusted based on the specific application). For example, a 1% retarder addition corresponds to 5 parts retarder per 500 parts cement. The comparative examples used the same addition amounts as the corresponding examples, with only the key components in the formulation adjusted.

[0097] Test method reference: "Technical Specifications for Highway Bridge and Culvert Construction" (JTG / T 3650-2020).

[0098] The results are shown in the following table:

[0099] Table 1 Test results of grouting properties prepared with different retarders

[0100]

[0101]

[0102] The data shows that the initial fluidity of the retarders of the present invention using different functional modifiers all outperformed commercial retarders, with minimal differences between them. This demonstrates that different modifiers have little effect on the initial fluidity of the grouting material, ensuring good workability. Furthermore, the use of unmodified humic acid in Comparative Example 1 significantly reduced the retarding effect and decreased hydrolysis resistance at high temperatures compared to Example 1, demonstrating the necessity of rare earth element modification of humic acid. Substituting sodium lignin sulfonate in Comparative Example 2 weakened the dispersion stability and synergistic retarding effect, demonstrating the irreplaceable role of the amphiphilic phosphonate dispersant in system performance. After 60 minutes, the fluidity of the grouting materials in each example was significantly better than that of the commercial retarder, demonstrating that the retarder system of the present invention performs well in slowing fluidity loss. The fluidity of Example 1 remained the best, demonstrating the advantages of nitrogen-containing borate complexes in this regard. The setting times of each example were significantly longer than those of the commercial retarder, demonstrating the excellent high-temperature retarding effect of the retarders of the present invention. The setting times were relatively similar using different modifiers, indicating that all effectively achieved retarding. In terms of 3d compressive strength, all examples are higher than the commercially available retarders, indicating that different functional regulators can effectively promote the later strength development of the grouting material while ensuring retarding, but there are slight differences in the values, reflecting that different regulators have slightly different degrees of promotion on strength development.

[0103] Test Example 2

[0104] The setting retarders of Examples 1-4 and Comparative Examples 1-3 were added to the grouting materials, and the setting delay time of the grouting materials was tested at temperatures of 35°C, 40°C, 45°C, and 50°C. The composition of the grouting materials and the amount of the retarder added were the same as those in Test Example 1.

[0105] Test method reference: Use the Vicat apparatus method to conduct multi-temperature gradient tests in accordance with (GB / T 1346-2011) "Test methods for water consumption, setting time and stability of cement of standard consistency".

[0106] The results are shown in the following table.

[0107] Table 2 Performance of grouting materials prepared with different retarders Test results of retarding time at different temperatures

[0108]

[0109]

[0110] As can be seen from the table above, as the temperature rises from 35°C to 50°C, the delay time of the grouting material corresponding to the retarder of the present invention using different functional regulators is shortened, but the overall time range is still maintained for a long time, and the fluctuation range of the delay time of each embodiment at different temperatures is relatively stable, which is significantly better than the commercially available retarder product (Comparative Example 3). This further confirms that the retarder system of the present invention has good temperature response characteristics. Different functional regulators can enable the retarder to provide a stable and effective delay effect for the grouting material in the temperature range of 35-50°C, which can meet the construction requirements of different temperature conditions in high temperature environments. However, there are certain differences in the slight changes in the delay time, reflecting that the response degree of different regulators to temperature changes is slightly different. At the same temperature, the delay time of rare earth modified humic acid (Example 1) is significantly better than that of unmodified humic acid (Comparative Example 1), and the dispersing synergistic effect of amphiphilic phosphonate (Example 1) makes its delay time significantly longer than that of sodium lignin sulfonate (Comparative Example 2), indicating that structural modification and dispersant synergy are the key to performance optimization.

[0111] Test Example 3

[0112] The retarders of Examples 1-4 and Comparative Examples 1-3 were added to the grout to compare their effects on the C3S hydration exothermic peak. The grout composition and retarder dosage were the same as in Experimental Example 1. The test method was based on the "Determination of Heat of Hydration of Cement" (GB / T 12959-2008).

[0113] The results are shown in the following table.

[0114] Table 2 Test results of C3S hydration exothermic peak of grouting materials prepared with different retarders

[0115] Retarder type Time of hydration exothermic peak appearance (h) Maximum hydration heat release rate (J / g·h) Example 1 12.5 85 Example 2 12.2 86 Example 3 12.0 87 Example 4 11.8 88 Comparative Example 1 10.4 98 Comparative Example 2 9.8 107 Comparative Example 3 6.8 120

[0116] As can be seen from the table above, the retarders in each example of the present invention significantly delayed the onset of the C3S hydration exothermic peak and significantly reduced the maximum hydration exothermic rate, demonstrating significant advantages over traditional retarders. This demonstrates that different functional modifiers can effectively inhibit the hydration reaction rate of cement and delay the hydration exothermic process. Comparative Example 1, in which ordinary humic acid was substituted for rare earth-modified humic acid, resulted in an earlier and higher peak C3S hydration exothermic peak in the grouting material, resulting in faster hydration progress. However, the high-temperature performance was inferior to that of Example 1. After replacing the dispersant in Comparative Example 2, the onset of the exothermic peak was not effectively delayed, resulting in a higher peak exothermic value, which affected the durability and stability of the grouting material.

[0117] The above is only a preferred embodiment of the invention and does not impose any formal limitation on the invention. Based on the technical essence of the invention and within the spirit and principles of the invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the invention.

Claims

1. A rare earth doped humic acid-based retarder, characterized in that: The raw materials include the following substances in parts by weight: 35-50 parts of rare earth modified humic acid, 10-15 parts of amphiphilic phosphonate dispersant, 5-8 parts of magnesium phosphate corrosion inhibitor, 8-12 parts of nano silicon dioxide, and 3-5 parts of functional regulator; The loading amount of the rare earth oxide in the rare earth modified humic acid is 8-12 wt %; the rare earth oxide is preferably one of lanthanum oxide, cerium oxide and yttrium oxide.

2. A rare earth doped humic acid-based retarder according to claim 1, characterized in that: The preparation method of the rare earth modified humic acid comprises the following steps: using an ion exchange method, soaking humic acid in a rare earth salt solution for a period of time, causing the carboxylic acid functional groups in the humic acid to undergo an ion exchange reaction with lanthanide element ions to achieve the loading of rare earth elements on the humic acid, and then filtering, washing, and drying to obtain the rare earth modified humic acid. Preferably, the concentration of the rare earth salt solution is 0.2-0.5 mol / L. The mass ratio of humic acid to rare earth salt is (0.5:1)-(1.5:1); The reaction time is 1.5-3 hours, and the reaction temperature is 50-70°C.

3. The rare earth-doped humic acid-based retarder according to claim 1, characterized in that: The preparation method of the amphiphilic phosphonate dispersant comprises the following steps: S1. The long-chain fatty alcohol is reacted with phosphorus oxychloride under a protective atmosphere by heating to form an intermediate phosphate monoester; S2. Adding a modified monomer containing a hydrophilic group, polyethylene glycol monomethyl ether, and a catalyst to the reaction system for dehydration condensation reaction to generate an amphiphilic phosphonate dispersant. Preferably, the long-chain fatty alcohol comprises stearyl alcohol; Preferably, the molar ratio of long-chain fatty alcohol to phosphorus oxychloride is 1:0.8-1.5, preferably 1:1.2; Preferably, in step S1, the reaction temperature is 80-90° C., and the reaction is carried out at a constant temperature for 4-6 hours; Preferably, the average molecular weight of the modified monomer polyethylene glycol monomethyl ether containing a hydrophilic group is 400-600; Preferably, the molar ratio of the modified monomer polyethylene glycol monomethyl ether to the intermediate is 1:1; Preferably, the catalyst is toluenesulfonic acid, and its amount is 0.5-1% of the total reactant mass; Preferably, in step S2, the dehydration condensation reaction is carried out at 110-120° C. for 3-5 hours; Preferably, in step S2, after the reaction is completed, the mixture is cooled, the pH is adjusted to neutral, the by-products are removed by filtration, and the final product is vacuum dried to obtain an amphiphilic phosphonate dispersant.

4. The rare earth-doped humic acid-based retarder according to claim 1, characterized in that: The particle size D50 of magnesium phosphate is ≤5 μm.

5. The rare earth-doped humic acid-based retarder according to claim 1, characterized in that: The specific surface area of ​​nano-silica is ≥200m 2 / g.

6. The rare earth-doped humic acid-based retarder according to claim 1, characterized in that: The functional regulator includes at least one of nitrogen-containing borate complexes, aminosulfonates, organic amines, and polyhydroxycarboxylates.

7. The method for preparing a rare earth-doped humic acid-based retarder according to any one of claims 1 to 6, characterized in that: The steps include: Step 1. Prepare the raw materials in proportion; Step 2. Self-assemble the rare earth modified humic acid and the amphiphilic phosphonate dispersant in a liquid phase at a mass ratio of 1:0.2-0.5, pH = 6-8, temperature 40-60°C, and time 1-3 hours to form a sustained-release unit with a core-shell structure; Preferably, the liquid phase is a water-ethanol mixture, and the volume ratio of water to ethanol is 8 to 10:1, more preferably 9:1; Preferably, the mass volume ratio of the rare earth modified humic acid to the water-ethanol mixture is 35-50g:500-700ml. Step 3. Place the slow-release unit, magnesium phosphate corrosion inhibitor, nano-silica and functional regulator obtained in step 2 into a mixing device for dry mixing to ensure that the components are preliminarily mixed evenly, and then grind and mix to prepare a finished retarder.

8. The method for preparing a rare earth-doped humic acid-based retarder according to claim 7, characterized in that: In step 3, the ball milling time is 2-4 hours and the rotation speed is 300-500 rpm.

9. Use of a rare earth-doped humic acid-based retarder according to any one of claims 1 to 6 in grouting.

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