An adaptive enhancer for seawater and sea sand concrete, its preparation method and application

Abstract

The present invention belongs to the technical field of concrete, and specifically relates to an adaptive reinforcing agent for seawater and sea sand concrete, and a preparation method and application thereof. The adaptive reinforcing agent of the present invention comprises the following components by weight: 20-40 parts of a modified polymer, 15-30 parts of a nano-silica sol, 8-15 parts of a nano-alumina sol, 2-5 parts of a surfactant, and 10-30 parts of water; the modified polymer is prepared by silane modification and polyetheramine grafting using an acrylic monomer. The modified polymer in the adaptive reinforcing agent for seawater and sea sand concrete of the present invention ensures stability in a seawater environment through a special molecular structure design; the Al-O-Si network formed by the nano-silica sol and the nano-alumina sol provides structural reinforcement; the synergistic effect of multiple components produces an adaptive reinforcement effect; and the introduction of the surfactant optimizes the dispersibility and compatibility of the reinforcing agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to an adaptive enhancer for seawater and sea sand concrete, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of marine engineering construction, the contradiction between supply and demand of concrete raw materials has become increasingly prominent. As a natural fine aggregate resource, sea sand has advantages such as rich reserves and convenient mining. However, its high salt content and poor particle morphology seriously restrict its application in concrete. At the same time, due to the increasingly scarce fresh water resources, the demand for using seawater to mix concrete is also becoming increasingly urgent. However, seawater and sea sand concrete faces serious problems such as accelerated chloride ion erosion, steel bar corrosion, and poor interfacial bonding, which seriously affect the service life of concrete structures.

[0003] Currently, the main method to improve the performance of seawater and sea sand concrete is to reduce the salt content of sea sand by fresh water rinsing. However, this method not only consumes a large amount of fresh water resources but also causes secondary pollution. In addition, the rinsed sea sand is prone to getting wet again during transportation and storage, and the effect is difficult to guarantee. Another commonly used method is to use mineral admixtures such as fly ash and slag to improve the density of concrete. However, such methods often reduce the early strength of concrete, affect the construction progress, and in a seawater environment, the activity of the admixtures is easily inhibited. In addition, there are also methods to adjust the working performance of concrete by using admixtures. However, traditional admixtures are prone to failure in a high-salt environment, lack continuous enhancement, and cannot cope with the performance fluctuations caused by changes in environmental conditions.

[0004] Especially in a complex marine environment, the performance of concrete will degrade with changes in environmental conditions such as temperature, humidity, and salinity, and even phenomena such as late strength regression and expansion cracking may occur. It is difficult for the existing technologies to achieve self-adaptive adjustment of concrete performance.

[0005] Therefore, an improved technical solution is needed to address the above deficiencies of the existing technologies. Summary of the Invention

[0006] The object of the present invention is to provide an adaptive enhancer for seawater and sea sand concrete, a preparation method thereof, and an application thereof, so as to help solve or improve the problem of poor durability that easily occurs in concrete applied to the marine environment.

[0007] To achieve the above object, the present invention provides the following technical solution: An adaptive enhancer for seawater and sea sand concrete, by weight, comprises the following components: 20-40 parts of modified polymer, 15-30 parts of nano-silica sol, 8-15 parts of nano-aluminum sol, 2-5 parts of surfactant, and 10-30 parts of water; The modified polymer is prepared by a method comprising the following steps: S1. Mix acrylic acid monomer, initiator, and chain transfer agent, and carry out free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2. Mix γ-aminopropyltrimethoxysilane, solvent, and the polyacrylic acid main chain, heat up and stir to react, and then carry out reduced pressure distillation to obtain a silane-modified product; S3. Carry out grafting reaction between the silane-modified product and polyetheramine to obtain the modified polymer.

[0008] Preferably, in step S1, the molar ratio of the acrylic acid monomer, initiator, and chain transfer agent is (100-120):(1-5):(0.5-3); the temperature of the free radical polymerization reaction is 70±5°C, and the reaction time is 4-6 h; in step S2, the molar ratio of γ-aminopropyltrimethoxysilane to the polyacrylic acid main chain is (15-25):1, and the molar ratio of the solvent to the polyacrylic acid main chain is (1-4):1; heat up to 120±5°C and stir to react for 3-5 h; in step S3, the molar ratio of the silane-modified product to polyetheramine is 1:(8-12); the temperature of the grafting reaction is 80±5°C, and the time is 2-4 h.

[0009] Preferably, the surfactant is at least one of polycarboxylate superplasticizer, naphthalene superplasticizer, and amino sulfonate superplasticizer.

[0010] The present invention also provides a preparation method for the adaptive enhancer for seawater and sea sand concrete, which adopts the following technical solution: The preparation method for the adaptive enhancer for seawater and sea sand concrete as described above comprises the following steps: (1) Dissolve the modified polymer in water to prepare a 15%-20% modified polymer solution; (2) Add the nano-silica sol to the modified polymer solution under stirring conditions; (3) Continue to stir and dropwise add the nano-aluminum sol; (4) Add surfactant and carry out ultrasonic dispersion; (5) Adjust the pH to 7-8 and carry out static stabilization to obtain the adaptive enhancer for seawater and sea sand concrete.

[0011] Preferably, in step (2), the stirring speed is 200-300 rpm, and the temperature is 25-30°C; in step (4), the ultrasonic power is 300-500 W, the frequency is 20-40 kHz, and the ultrasonic dispersion time is 15-20 min; in step (5), the static stabilization temperature is 20-30°C, the static stabilization time is 12-36 h, and the static stabilization is carried out in an environment with a relative humidity ≤65%.

[0012] The present invention also provides a seawater and sea sand concrete, which adopts the following technical solution: A seawater and sea sand concrete, the components of the seawater and sea sand concrete include the self-adaptive enhancer for seawater and sea sand concrete, seawater and sea sand as described above.

[0013] Preferably, by weight parts, the seawater and sea sand concrete includes the following components: 100 parts of cement, 150 - 180 parts of sea sand, 200 - 240 parts of crushed stone, 3 - 8 parts of the self-adaptive enhancer for seawater and sea sand concrete as described above, and 35 - 45 parts of seawater.

[0014] Preferably, the fineness modulus of the sea sand is 2.3 - 3.0, the mud content is less than 3%, the shell content is less than 3%, and the chloride ion content is less than 0.06%; the particle size of the crushed stone is 5 - 20 mm, the mud content is less than 1%, and the content of needle-like and flaky particles is less than 10%; the cement is ordinary Portland cement, and the strength grade is not less than 42.5.

[0015] The present invention also provides a preparation method of the seawater and sea sand concrete as described above, which adopts the following technical solution: A preparation method of seawater and sea sand concrete, including the following steps: I. Mix the cement, sea sand, crushed stone, the self-adaptive enhancer for seawater and sea sand concrete as described above, and seawater to obtain a mixture; II. Stir the mixture evenly, pour and mold it, and cure the molded part.

[0016] Preferably, the preparation of the seawater and sea sand concrete is carried out under the following environment: the temperature is 20 - 30 °C, and the relative humidity is 60% - 80% (all the following concrete preparation temperature and humidity are modified to this range); the curing conditions are: soak the molded part in seawater at 40 - 50 °C for curing.

[0017] Beneficial effects:

[0018] (1) The present invention innovatively combines a modified polymer and a nano sol, and designs and develops a new type of self-adaptive enhancer. The modified polymer in the self-adaptive enhancer for seawater and sea sand concrete of the present invention ensures its stability in a seawater environment through a special molecular structure design; the Al-O-Si network formed by nano silica sol and nano alumina sol provides structural enhancement; the synergistic effect of multiple components produces a self-adaptive enhancement effect; at the same time, the introduction of a surfactant optimizes the dispersibility and compatibility of the enhancer; this design concept provides a new technical route for solving the durability problem of seawater and sea sand concrete.

[0019] (2) The modified polymer in the self - adaptive enhancer of the present invention adopts a unique multi - level molecular design: the main chain is a carboxylated polyacrylic acid skeleton. The introduction of silane groups enables the modified polymer to achieve chemical bonding with cement hydration products, and the grafting of amino terminals provides pH responsiveness. This multi - functional molecular structure enables the material to remain stable in a seawater environment and automatically adjust the degree of ionization with environmental changes, achieving self - adaptive performance.

[0020] (3) The synergistic effect of nano - silica sol and nano - alumina sol constructs a three - dimensional cross - linked network inside the concrete. A rigid skeleton is established through the formation of Al - O - Si bonds, filling the pores between cement hydration products and significantly improving the mechanical properties of the concrete (for example, the self - adaptive enhancer for seawater - sea sand concrete of the present invention can make the 28 - day compressive strength of the concrete ≥50 MPa, the 100 - day compressive strength increase by more than 10% compared with the 28 - day strength, and the crack self - repair rate exceed 90%).

[0021] (4) The self - adaptive enhancer for seawater - sea sand concrete of the present invention has a significant ion balance regulation ability: in a high - salt environment, the carboxyl groups of the modified polymer can form chelates with Ca 2+ to reduce the free Ca 2+ concentration; the hydroxyl groups on the surface of the nano - sol can fix Cl - through ion - exchange to form a stable electric double - layer structure. This synergistic effect makes the compressive strength of the concrete after being soaked for 100 days better than that of seawater - sea sand concrete with the same mix ratio without adding the self - adaptive enhancer by more than 30%.

[0022] (5) The self - adaptive enhancer system for seawater - sea sand concrete of the present invention has multiple action mechanisms: it realizes the uniform dispersion of cement particles through electrostatic and steric effects, improving the workability of the concrete; forms a nano - scale transition layer on the surface of the aggregate to improve the interfacial bonding performance; provides multi - scale strengthening effects through an inorganic - organic hybrid network; and can automatically adjust the system performance according to environmental conditions to maintain long - term stability.

[0023] (6) The seawater - sea sand concrete of the present invention exhibits excellent comprehensive performance: it has good mechanical properties and durability (for example, the late - stage crack self - repair rate after being soaked for 100 days can be increased by more than 50% compared with seawater - sea sand concrete with the same mix ratio without adding the self - adaptive enhancer), making it have broad application prospects in engineering such as ocean engineering, port terminals, cross - sea bridges, and offshore wind power. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0025] Figure 1 Schematic molecular structure diagram of the self - adaptive enhancer for seawater - sea - sand concrete provided in Embodiment 1 of the present invention.

[0026] Figure 2 Schematic structure diagram of seawater - sea - sand concrete after being soaked for 100 days; among them, (a) is seawater - sea - sand concrete without adding an enhancer; (b) is seawater - sea - sand concrete after adding the self - adaptive enhancer.

[0027] Figure 3 SEM micrographs of the microstructure of seawater - sea - sand concrete in Embodiment 1 and Comparative Example 7 of the present invention; among them, the left figure is the SEM micrograph of the seawater - sea - sand concrete in Comparative Example 7; the right figure is the SEM micrograph of the interfacial transition zone structure and the enhanced product of the seawater - sea - sand concrete in Embodiment 1. Detailed implementation manners

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0029] The present invention will be described in detail below in conjunction with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0030] Aiming at the problem that the concrete currently applied in the marine environment has poor durability (for example, the performance of the concrete degrades, the strength reverses, or it expands and cracks with the change of environmental conditions), the present invention provides a self - adaptive enhancer for seawater - sea - sand concrete.

[0031] When solving this technical problem, the inventors thought that an ideal enhancer should be able to form stable chemical bonds with the hydration products of cement, construct a three - dimensional network structure to improve the mechanical properties of concrete, have the ability to regulate ion balance to cope with the complex marine environment, and form a protective passivation film to reduce chloride ion penetration; based on this inventive concept, the self - adaptive enhancer for seawater - sea - sand concrete of the present invention was constructed.

[0032] The self-adaptive enhancer for seawater and sea-sand concrete of the present invention comprises the following components in parts by weight: 20-40 parts of a modified polymer (for example, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts), 15-30 parts of nano-silica sol (for example, 15 parts, 18 parts, 21 parts, 24 parts, 27 parts or 30 parts), 8-15 parts of nano-aluminum sol (for example, 8 parts, 10 parts, 12 parts, 14 parts or 15 parts), 2-5 parts of a surfactant (for example, 2 parts, 3 parts, 4 parts or 5 parts) and 10-30 parts of water (for example, 10 parts, 15 parts, 20 parts, 25 parts or 30 parts); the modified polymer is prepared by a method comprising the following steps: S1. Mix acrylic acid monomers, initiators and chain transfer agents, and carry out free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2. Mix γ-aminopropyltrimethoxysilane, a solvent and the polyacrylic acid main chain, heat up and stir for reaction, and then carry out reduced pressure distillation to obtain a silane-modified product; S3. Carry out grafting reaction on the silane-modified product and polyetheramine to obtain the modified polymer. Wherein, the reaction mechanism of step S1 is:

[0033]

[0034] The reaction mechanism of step S2 is:

[0035]

[0036] The reaction mechanism of step S3 is:

[0037]

[0038] The key role of γ-aminopropyltrimethoxysilane in the present invention is: to form chemical bonding with cement hydration products through silane groups (alkoxy groups can react with cement hydration products), to provide pH responsiveness through amino groups, and to participate in the formation of a multi-functional molecular structure of the modified polymer (with an appropriate carbon chain length to help ensure the flexibility of the modified polymer molecules); if γ-aminopropyltrimethoxysilane is replaced by other silanes, it will affect its grafting reaction with the polyacrylic acid main chain, affect the pH responsiveness of the modified polymer, and affect the chemical bonding strength with cement hydration products.

[0039] The modified polymer in the self-adaptive enhancer for seawater and sea-sand concrete of the present invention is a multi-functional macromolecule, and the following functions can be realized through special molecular design (refer to Figure 1-2):The carboxylated backbone provides dispersibility, the silyl groups enable chemical bonding, and the amino terminus provides pH responsiveness; this structure of the modified polymer allows it to exhibit excellent self-adaptive performance in a seawater environment; the synergistic effect of nano-silica sol and nano-alumina sol enables the construction of a three-dimensional cross-linked network inside the concrete; a rigid framework is established through the formation of Al-O-Si bonds, filling the pores between the cement hydration products and significantly improving the mechanical properties of the concrete; the enhancer of the present invention has a significant ability to regulate ion balance. In a high-salt environment, the carboxyl groups of the modified polymer can form chelates with Ca 2+ to reduce the free Ca 2+ concentration; the hydroxyl groups on the surface of the nano-sol can fix Cl - through ion exchange to form a stable electric double layer structure; the self-adaptive enhancer system for seawater sea-sand concrete of the present invention has multiple action mechanisms: uniform dispersion of cement particles is achieved through electrostatic and steric effects (synergistic effect of surfactant and modified polymer; among them, the carboxylated backbone of the modified polymer helps to provide dispersibility, and the multi-level molecular structure helps to provide steric stability), improving the workability of the concrete; a nano-scale transition layer is formed on the surface of the aggregate to improve the interfacial bonding performance; multi-scale strengthening effects are provided through an inorganic-organic hybrid network; it can automatically adjust the system performance according to environmental conditions to maintain long-term stability (as Figure 2 shown, Figure 2 (a) in is the concrete matrix incorporated with the self-adaptive enhancer of the present invention, and (b) is the seawater sea-sand concrete matrix without the self-adaptive enhancer of the present invention; after incorporating the self-adaptive enhancer of the present invention, the concrete matrix has the effect of self-adaptive strengthening, with smaller pores and higher crack self-healing ability).

[0040] The self-adaptive enhancer for seawater sea-sand concrete of the present invention has excellent self-adaptive performance and strengthening effect, can significantly improve the mechanical properties and durability of seawater sea-sand concrete, and has broad application prospects in engineering such as ocean engineering, port terminals, cross-sea bridges, and offshore wind power.

[0041] In a preferred embodiment of the self-adaptive enhancer for seawater and sea sand concrete of the present invention, in step S1, the molar ratio of acrylic monomer, initiator and chain transfer agent is (100 - 120):(1 - 5):(0.5 - 3) (for example, 100:1:0.5, 120:1:0.5, 100:5:3, 100:3:2, 120:5:3, 110:1:0.5, 110:5:3, 110:3:2.5, 110:3:0.5 or 110:3:3, etc.), the temperature of the free radical polymerization reaction is 70 ± 5 °C (for example, 65 °C, 68 °C, 70 °C, 72 °C or 75 °C), and the time is 4 - 6 h (for example, 4 h, 4.5 h, 5 h, 5.5 h or 6 h); in step S2, the molar ratio of γ-aminopropyltrimethoxysilane to the polyacrylic acid main chain is (15 - 25):1 (for example, 15:1, 18:1, 20:1, 22:1 or 25:1), the molar ratio of the solvent to the polyacrylic acid main chain is (1 - 4):1 (for example, 1:1, 2:1, 3:1 or 4:1), heat up to 120 ± 5 °C (for example, 115 °C, 118 °C, 120 °C or 125 °C), and stir and react for 3 - 5 h (for example, 3 h, 3.5 h, 4 h, 4.5 h or 5 h); in step S3, the molar ratio of the silane modified product to polyetheramine is 1:(8 - 12) (for example, 1:8, 1:9, 1:10, 1:11 or 1:12), the temperature of the grafting reaction is 80 ± 5 °C (for example, 75 °C, 78 °C, 80 °C, 83 °C or 85 °C), and the time is 2 - 4 h (for example, 2 h, 2.5 h, 3 h, 3.5 h or 5 h). Among them, if the dosage ratio of γ-aminopropyltrimethoxysilane is too large (for example, >25:1), the adverse effects are as follows: (1) In terms of the product: Excessive silane groups will lead to too high a crosslinking degree; the solubility of the modified polymer decreases, the molecular structure rigidity is too large, and the flexibility decreases; (2) In terms of performance: The self-adaptive performance decreases, the pH response ability weakens; the dispersion compatibility with cement particles becomes poor; local silane enrichment areas may be formed, affecting the uniformity; the material cost increases; (3) In terms of the process: The viscosity of the reaction system increases; the processing difficulty of the product increases; more side reactions may occur. If the dosage ratio of γ-aminopropyltrimethoxysilane is too small (for example, <15:1), the adverse effects are as follows: (1) In terms of the product: The degree of silane modification is insufficient, the chemical bonding sites are insufficient, and the network structure formation is incomplete; (2) In terms of performance: The chemical bonding with cement hydration products is insufficient, the strengthening effect is significantly reduced, the self-adaptive adjustment ability is limited, and the durability performance decreases; (3) In terms of the application effect: The development of concrete strength is limited, the interfacial bonding performance is poor, the crack resistance performance decreases, and the self-healing ability is insufficient.If the dosage of polyetheramine in step S3 is too large, the hydrophilicity of the final product will be too strong, affecting its compatibility with the cement system, and excessive free polyetheramine may interfere with the cement hydration process; if the dosage of polyetheramine is too small, due to incomplete grafting reaction, the number of pH-responsive groups in the product will be insufficient, and the expected self-adaptive regulation function cannot be achieved. Through systematic research, the molar ratio of the silane-modified product to polyetheramine in the range of 1:(8-12) is the most suitable. At this time, a modified polymer with a complete structure and excellent performance can be obtained, ensuring its ideal strengthening effect in seawater and sea sand concrete.

[0042] Preferably, the initiator is selected from at least one of ammonium persulfate, potassium persulfate, azobisisobutyronitrile, and benzoyl peroxide; the chain transfer agent is selected from at least one of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol, and thiol.

[0043] Preferably, the solvent is at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and dimethylacetamide (DMAC).

[0044] In a preferred embodiment of the self-adaptive strengthening agent for seawater and sea sand concrete of the present invention, the surfactant is at least one of polycarboxylate-based water reducers, naphthalene-based water reducers, and amino sulfonate-based water reducers. Among them, polycarboxylate water reducers can provide a steric hindrance effect, while naphthalene-based water reducers and amino sulfonate-based water reducers provide an electrostatic repulsion effect.

[0045] The present invention also provides a method for preparing an adaptive enhancer for seawater and sea sand concrete as described above. The method for preparing the adaptive enhancer for seawater and sea sand concrete according to the embodiments of the present invention includes the following steps: (1) Dissolve the modified polymer in water to prepare a 15%-20% (for example, 15%, 16%, 17%, 18%, 19% or 20%) modified polymer solution; (2) Add nano-silica sol to the modified polymer solution under stirring conditions; (3) Continue stirring and dropwise add nano-aluminum sol; (4) Add a surfactant and perform ultrasonic dispersion; (5) Adjust the pH to 7-8 (for example, 7, 7.2, 7.4, 7.6, 7.8 or 8), and let it stand for stabilization, thus obtaining the adaptive enhancer for seawater and sea sand concrete. Among them, the step of ultrasonic dispersion can not only achieve the uniform mixing of each component, but more importantly, through the ultrasonic cavitation effect: (1) effectively break the agglomeration of nano-sol and promote its uniform dispersion with the modified polymer; (2) enhance the dispersion effect of the surfactant and form a stable colloidal system; (3) promote the interaction between the modified polymer and nano-sol and optimize the interface structure; (4) contribute to the formation of a more uniform three-dimensional network structure and improve the product performance. In step (5), if the pH is adjusted to pH>8, the following adverse effects will occur: excessive ionization of amino groups in the modified polymer, resulting in molecular conformation changes; decreased stability of nano-sol, prone to aggregation; increased viscosity of the system, which is not conducive to engineering applications; may accelerate cement hydration and affect the workability of concrete. If the pH is adjusted to pH<7, the following adverse effects will occur: limited pH-responsive ability of the modified polymer; poor dispersibility of nano-sol; hindered formation of the Al-O-Si network structure; reduced system stability, prone to phase separation; poor compatibility with the cement system.

[0046] In addition, the addition sequence of each component in the present invention has a significant impact on the product performance: Advantages of the correct sequence (modified polymer solution → nano-silica sol → nano-aluminum sol → surfactant): Ensure the full dissolution of the modified polymer; facilitate the gradual dispersion of nano-sol; promote the orderly formation of the Al-O-Si network; the surfactant can finally optimize the dispersion effect. The wrong sequence may lead to: agglomeration of nano-sol, uneven dispersion of the modified polymer, incomplete network structure, poor system stability, reduced enhancement effect; in particular, if nano-aluminum sol is added first, it is easy to form aggregates with the modified polymer, affecting the subsequent dispersion of nano-silica sol and being not conducive to the formation of an ideal three-dimensional network; if the surfactant is added in advance, it will affect the dissolution of the modified polymer, interfere with the dispersion of nano-sol, and reduce the dispersion enhancement effect.

[0047] Preferably, in step (5), the temperature for static stabilization is 20 - 30 °C (e.g., 20 °C, 22 °C, 24 °C, 26 °C, 28 °C or 30 °C), the time for static stabilization is 12 - 36 h (e.g., 12 h, 16 h, 20 h, 25 h, 30 h or 36 h), and the static stabilization is carried out in an environment with a relative humidity ≤ 65%. Among them, if the temperature is too high (> 30 °C), the system ripening will be accelerated, which may lead to component separation and affect the product stability; if the temperature is too low (< 20 °C), the stabilization process will be prolonged, and the interaction between components is insufficient, affecting the final performance; if the time for static stabilization is too short (< 12 hours), the system has not reached sufficient equilibrium, the stability is insufficient, and the performance is unstable; if the time for static stabilization is too long (> 36 hours), the production cycle will be increased, and component sedimentation may also occur, which is uneconomical; by controlling the humidity of the environment during static stabilization, it helps to avoid concentration changes and product performance fluctuations caused by water evaporation.

[0048] In a preferred embodiment of the preparation method of the self - adaptive enhancer for seawater - sea - sand concrete of the present invention, in step (2), the stirring speed is 200 - 300 rpm (e.g., 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm or 300 rpm), and the temperature is 25 - 30 °C (e.g., 25 °C, 26 °C, 27 °C, 28 °C, 29 °C or 30 °C); in step (4), the ultrasonic power is 300 - 500 W (e.g., 300 W, 330 W, 360 W, 390 W, 420 W, 450 W, 480 W or 500 W), the frequency is 20 - 40 kHz (e.g., 20 kHz, 24 kHz, 28 kHz, 32 kHz, 36 kHz or 40 kHz), and the ultrasonic dispersion time is 15 - 20 min (e.g., 15 min, 16 min, 17 min, 18 min, 19 min or 20 min).

[0049] The present invention also proposes a seawater - sea - sand concrete. The components of the seawater - sea - sand concrete in the embodiments of the present invention include the self - adaptive enhancer for seawater - sea - sand concrete as described above, seawater and sea - sand.

[0050] In a preferred embodiment of the seawater and sea sand concrete of the present invention, by weight, the seawater and sea sand concrete comprises the following components: 100 parts of cement, 150 - 180 parts of sea sand (for example, 150 parts, 160 parts, 170 parts or 180 parts), 200 - 240 parts of crushed stone (for example, 200 parts, 210 parts, 220 parts, 230 parts or 240 parts), 3 - 8 parts of the self - adaptive enhancer for seawater and sea sand concrete as described above (for example, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts), and 35 - 45 parts of seawater (for example, 35 parts, 37 parts, 39 parts, 41 parts, 43 parts or 45 parts). Among them, the adverse effects when the dosage of the self - adaptive enhancer is too large (for example, > 8 parts): (1) Influence on the fresh properties of concrete: The slump is too large, resulting in poor workability, difficult to control fluidity, increased risk of bleeding and segregation, and too long initial setting time; (2) Influence on mechanical properties: The strength development is hindered, the elastic modulus is reduced, the interfacial bonding effect is poor, and the internal defects increase; (3) Influence on durability: The risk of shrinkage and cracking increases, the impermeability performance decreases, the chloride ion permeability increases, and the long - term stability becomes poor; (4) Other aspects: Increase the project cost, affect the construction progress, and reduce environmental friendliness. The adverse effects when the dosage of the self - adaptive enhancer is too small (for example, < 3 parts): (1) Insufficient enhancement effect: The increase in compressive strength is limited, the crack resistance is poor, the self - repair ability is insufficient, and the interfacial enhancement effect is not obvious; (2) Durability problems: Weak chloride ion penetration resistance, poor anti - seawater erosion effect, insufficient self - adaptive adjustment ability, and rapid long - term performance decay; (3) Microstructural defects: Higher porosity, loose structure in the interfacial transition zone, incomplete three - dimensional network structure, and low crack self - repair rate; (4) Influence on engineering applications: Unable to meet the durability requirements of marine engineering, shorten the service life, and increase the maintenance cost. The advantages of the dosage of the self - adaptive enhancer within the optimal dosage range (3 - 8 parts): (1) Performance optimization: Reasonable strength development, good workability, dense interfacial structure, and strong self - repair ability; (2) Durability guarantee: Low chloride ion permeability coefficient, good anti - seawater erosion performance, strong self - adaptive adjustment ability, and stable long - term performance; (3) Economic rationality: Optimal cost - benefit ratio, convenient construction, and low maintenance cost; Therefore, through a large number of experimental studies and engineering practices, it is proved that controlling the dosage of the self - adaptive enhancer within the range of 3 - 8 parts is the most reasonable, which can ensure that the seawater and sea sand concrete obtains ideal comprehensive performance.

[0051] Preferably, the dosage of the self - adaptive enhancer is 5 - 6 parts, at this time, the best enhancement effect and economy can be obtained.

[0052] Preferably, the seawater and sea sand concrete comprises 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stones, 40 parts of seawater and 3 - 8 parts of self - adaptive enhancer; or, the seawater and sea sand concrete comprises 100 parts of cement, 160 parts of sea sand, 210 parts of crushed stones, 38 parts of seawater and 3 - 8 parts of self - adaptive enhancer; or, the seawater and sea sand concrete comprises 100 parts of cement, 170 parts of sea sand, 225 parts of crushed stones, 42 parts of seawater and 3 - 8 parts of self - adaptive enhancer; or, the seawater and sea sand concrete comprises 100 parts of cement, 175 parts of sea sand, 230 parts of crushed stones, 43 parts of seawater and 3 - 8 parts of self - adaptive enhancer; or, the seawater and sea sand concrete comprises 100 parts of cement, 155 parts of sea sand, 215 parts of crushed stones, 37 parts of seawater and 3 - 8 parts of self - adaptive enhancer;

[0053] or, the seawater and sea sand concrete comprises 100 parts of cement, 180 parts of sea sand, 235 parts of crushed stones, 45 parts of seawater and 3 - 8 parts of self - adaptive enhancer.

[0054] In a preferred embodiment of the seawater and sea sand concrete of the present invention, the fineness modulus of the sea sand is 2.3 - 3.0, the mud content is less than 3%, the shell content is less than 3%, and the chloride ion content is less than 0.06%; the particle size of the crushed stones is 5 - 20 mm, the mud content is less than 1%, and the content of needle - like and flaky particles is less than 10%; the cement is ordinary Portland cement with a strength grade not lower than 42.5; the seawater is obtained by filtering natural seawater (only obvious impurities in natural seawater need to be removed).

[0055] The present invention also provides a preparation method of the seawater and sea sand concrete as described above. The preparation method of the seawater and sea sand concrete in the embodiments of the present invention includes the following steps: I. Mix cement, sea sand, crushed stones, the self - adaptive enhancer for seawater and sea sand concrete as described above and seawater to obtain a mixture; II. Stir the mixture evenly, pour and form, and cure the formed part.

[0056] In a preferred embodiment of the method for preparing seawater and sea sand concrete of an embodiment of the present invention, the preparation of seawater and sea sand concrete is carried out under the following environment: the temperature is 20-30°C (for example, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C), and the relative humidity is 60%-80% (for example, 60%, 65%, 70%, 75% or 80%); the curing conditions are: the molded parts are immersed in 40-50°C (for example, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C) seawater for curing. Among them, the temperature of seawater during curing is close to the environmental temperature of the South China Sea islands and reefs; curing under immersion in seawater is more prone to strength shrinkage and concrete cracking than curing under standard conditions. The present invention helps to improve the phenomenon of strength shrinkage and cracking of seawater and sea sand concrete in an immersion environment by adding an appropriate amount of adaptive reinforcing agent to seawater and sea sand concrete. If the temperature of seawater is too high during curing, it will lead to too rapid hydration, increased internal stress, increased risk of microcracks, and uneven organizational structure; if the temperature of seawater is too low during curing, it will lead to a slow cement hydration rate, slow strength development, insufficient activity of the adaptive reinforcer, and imperfect network structure formation.

[0057] The self-adaptive reinforcing agent for seawater and sea sand concrete of the present invention, as well as its preparation method and application are described in detail below through specific embodiments.

[0058] In the following examples, nano-aluminum sol: Zhejiang Zhitai Nano Micro New Materials Co., Ltd., model: JR14W, pH: 7.0-8.0; nano-silica sol: Yousuo Sample Co., Ltd., model: JN-30, pH: 9.0-10.5; polycarboxylic acid water reducer: Jianye Chemical, model JY-PCA, solid content 40%; naphthalene water reducer: Liansheng Chemical, model LS-2, solid content 35%; acrylic acid monomer: Akema, purity ≥99.5%; γ-aminopropyltrimethoxysilane: Dow Corning, purity ≥98%; polyetheramine: Huntsman, model D400, molecular weight about 400; initiator: ammonium persulfate, Aladdin, purity ≥98%; chain transfer agent: thioglycolic acid, Sigma, purity ≥98%;

[0059] The fineness modulus of sea sand is 2.3-3.0, the mud content is less than 3%, the shell content is less than 3%, and the chloride ion content is less than 0.06%; the particle size of crushed stone is 5-20mm, the mud content is less than 1%, and the needle-like particle content is less than 10%; the cement is ordinary Portland cement (PO 42.5).

[0060] Example 1

[0061] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment includes, by weight: 40 parts of modified polymer, 30 parts of nano silica sol, 15 parts of nano aluminum sol, 5 parts of surfactant and 30 parts of water; wherein the modified polymer is prepared by silane modification and polyetheramine grafting of acrylic acid monomer; the surfactant is a mixture of polycarboxylic acid water reducer and naphthalene water reducer (the mass ratio of the two is 4:1), and includes, by weight: 4 parts of polycarboxylic acid water reducer and 1 part of naphthalene water reducer.

[0062] Specifically, the modified polymer is prepared by a method comprising the following steps:

[0063] S1. In a reactor equipped with a thermometer, a stirring device and nitrogen protection, acrylic acid monomer, an initiator and a chain transfer agent are mixed (the molar ratio of acrylic acid monomer, initiator and chain transfer agent is 100:1:0.5), and stirred at 70° C. for 4 hours to obtain a polyacrylic acid main chain for standby use;

[0064] S2. In the same reactor, γ-aminopropyltrimethoxysilane, N,N-dimethylformamide and polyacrylic acid main chain are mixed (the molar ratio of γ-aminopropyltrimethoxysilane, DMF and polyacrylic acid main chain is 20:2:1), and stirred at 120° C. for 3 h to obtain a silane-modified product for standby use;

[0065] S3. reacting the silane-modified product with polyetheramine (the molar ratio of the silane-modified product to the polyetheramine is 1:10) at 80° C. for 2 h to obtain a modified polymer.

[0066] The method for preparing the adaptive reinforcing agent for seawater and sea sand concrete of this embodiment comprises the following steps:

[0067] (1) dissolving the modified polymer in water to prepare an 18% solution;

[0068] (2) Slowly adding nano-silica sol under stirring conditions of 25°C and 250 rpm;

[0069] (3) Continue stirring and add nano aluminum sol dropwise;

[0070] (4) adding a surfactant and performing ultrasonic dispersion at 400 W and 30 kHz for 18 min;

[0071] (5) The pH value is adjusted to 7.5 with sodium hydroxide solution, and the mixture is allowed to stand for 24 hours to obtain the self-adaptive reinforcing agent for seawater and sea sand concrete of this embodiment.

[0072] The seawater and sea sand concrete of this embodiment includes, by weight, 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 5 parts of the adaptive enhancer of this embodiment and 40 parts of seawater.

[0073] The preparation method of the seawater and sea sand concrete of this embodiment includes the following steps: I. Mix cement, sea sand, crushed stone, the self-adaptive enhancer of this embodiment and seawater to obtain a mixture;

[0074] II. Stir the mixture evenly, pour it into a mold, and cure the formed specimen (cure it by soaking in seawater at 45°C). The preparation of the seawater and sea sand concrete of this embodiment is carried out in an environment of 20 - 30°C and a relative humidity of 60% - 80% (before curing).

[0075] Example 2

[0076] The self-adaptive enhancer for seawater and sea sand concrete of this embodiment, by weight, includes: 20 parts of modified polymer, 15 parts of nano-silica sol, 8 parts of nano-alumina sol, 2 parts of surfactant and 10 parts of water; wherein, the modified polymer is prepared by modifying acrylic monomers with silane and grafting with polyetheramine (prepared by the same method as in Example 1); the surfactant is a mixture of polycarboxylate-based water reducer and naphthalene-based water reducer (the mass ratio of the two is 3:1), and by mass, it includes: 1.5 parts of polycarboxylate-based water reducer and 0.5 part of naphthalene-based water reducer.

[0077] The preparation method of the self-adaptive enhancer for seawater and sea sand concrete of this embodiment is the same as that of Example 1.

[0078] The seawater and sea sand concrete of this embodiment, by weight, includes: 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 3 parts of the self-adaptive enhancer of this embodiment and 40 parts of seawater.

[0079] The preparation method of the seawater and sea sand concrete of this embodiment is the same as that of Example 1.

[0080] Example 3

[0081] The self-adaptive enhancer for seawater and sea sand concrete of this embodiment, by weight, includes: 30 parts of modified polymer, 25 parts of nano-silica sol, 12 parts of nano-alumina sol, 4 parts of surfactant and 20 parts of water; wherein, the modified polymer is prepared by modifying acrylic monomers with silane and grafting with polyetheramine (prepared by the same method as in Example 1); the surfactant is a mixture of polycarboxylate-based water reducer, naphthalene-based water reducer and amino sulfonate-based water reducer (the mass ratio of the three is 2:1:1), and by mass, it includes: 2 parts of polycarboxylate-based water reducer, 1 part of naphthalene-based water reducer and 1 part of amino sulfonate-based water reducer.

[0082] The preparation method of the self-adaptive enhancer for seawater and sea sand concrete of this embodiment is the same as that of Example 1.

[0083] The seawater and sea sand concrete of this embodiment includes, by weight, 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 4 parts of the adaptive enhancer of this embodiment and 40 parts of seawater.

[0084] The preparation method of seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0085] Example 4

[0086] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment includes, by weight: 35 parts of modified polymer, 28 parts of nano silica sol, 13 parts of nano aluminum sol, 3 parts of surfactant and 25 parts of water; wherein the modified polymer is prepared by silane modification and polyetheramine grafting of acrylic acid monomer (prepared by the same method as in Example 1); the surfactant is a polycarboxylic acid-based water reducer.

[0087] The preparation method of the adaptive reinforcing agent for seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0088] The seawater and sea sand concrete of this embodiment includes, by weight, 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 6 parts of the adaptive enhancer of this embodiment, and 40 parts of seawater.

[0089] The preparation method of seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0090] Example 5

[0091] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment includes, by weight: 25 parts of modified polymer, 20 parts of nano silica sol, 10 parts of nano aluminum sol, 3 parts of surfactant and 15 parts of water; wherein the modified polymer is prepared by silane modification and polyetheramine grafting of acrylic acid monomer (prepared by the same method as in Example 1); the surfactant is a mixture of naphthalene-based water reducer and aminosulfonic acid-based water reducer (the mass ratio of the two is 2:1), and includes, by weight: 2 parts of naphthalene-based water reducer and 1 part of aminosulfonic acid-based water reducer.

[0092] The preparation method of the adaptive reinforcing agent for seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0093] The seawater and sea sand concrete of this embodiment includes, by weight, 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 7 parts of the adaptive enhancer of this embodiment and 40 parts of seawater.

[0094] The preparation method of seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0095] Example 6

[0096] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment includes, by weight: 38 parts of modified polymer, 27 parts of nano silica sol, 14 parts of nano aluminum sol, 4.5 parts of surfactant and 28 parts of water; wherein the modified polymer is prepared by silane modification and polyetheramine grafting of acrylic acid monomer (prepared by the same method as in Example 1); the surfactant is a mixture of polycarboxylic acid water reducer, naphthalene water reducer and aminosulfonic acid water reducer (the mass ratio of the three is 2:1.5:1), and includes, by weight: 2 parts of polycarboxylic acid water reducer, 1.5 parts of naphthalene water reducer and 1 part of aminosulfonic acid water reducer.

[0097] The preparation method of the adaptive reinforcing agent for seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0098] The seawater and sea sand concrete of this embodiment includes, by weight, 100 parts of cement, 165 parts of sea sand, 220 parts of crushed stone, 8 parts of the adaptive enhancer of this embodiment, and 40 parts of seawater.

[0099] The preparation method of seawater and sea sand concrete in this embodiment is the same as that in Example 1.

[0100] Comparative Example 1

[0101] The reinforcing agent of this comparative example differs from that of Example 1 only in that the modified polymer is omitted; the rest is consistent with Example 1 (ie, the reinforcing agent of this comparative example includes 30 parts of nano-silica sol, 15 parts of nano-aluminum sol, 5 parts of surfactant and 30 parts of water).

[0102] The preparation method of the reinforcing agent in this comparative example is different from that in Example 1 only in that the step of adding the modified polymer is omitted; the rest is the same as in Example 1.

[0103] The raw material proportions of the seawater and sea sand concrete and the preparation method of the seawater and sea sand concrete in this comparative example are consistent with those in Example 1.

[0104] Comparative Example 2

[0105] The only difference between the reinforcing agent in this comparative example and that in Example 1 is that the amount of the modified polymer is increased to 55 parts; the rest is the same as in Example 1.

[0106] That is, by weight, the reinforcing agent of this comparative example includes: 55 parts of modified polymer (prepared by the same method as in Example 1), 30 parts of nano silica sol, 15 parts of nano aluminum sol, 5 parts of surfactant and 30 parts of water.

[0107] The preparation method of the reinforcing agent, the raw material ratio of the seawater and sea sand concrete, and the preparation method of the seawater and sea sand concrete in this comparative example are all consistent with those in Example 1.

[0108] Comparative Example 3

[0109] The difference between the intensifier of this comparative example and that of Example 1 is only that: the dosage of nano-silica sol is increased to 40 parts; the rest are the same as those of Example 1.

[0110] That is, by weight, the intensifier of this comparative example includes: 40 parts of modified polymer (prepared in the same way as in Example 1), 40 parts of nano-silica sol, 15 parts of nano-aluminum sol, 5 parts of surfactant, and 30 parts of water.

[0111] The preparation method of the intensifier of this comparative example, the raw material ratio of seawater sea-sand concrete, and the preparation method of seawater sea-sand concrete are all the same as those of Example 1.

[0112] Comparative Example 4

[0113] The difference between the intensifier of this comparative example and that of Example 1 is only that: the dosage of nano-aluminum sol is increased to 20 parts; the rest are the same as those of Example 1.

[0114] That is, by weight, the intensifier of this comparative example includes: 40 parts of modified polymer (prepared in the same way as in Example 1), 30 parts of nano-silica sol, 20 parts of nano-aluminum sol, 5 parts of surfactant, and 30 parts of water.

[0115] The preparation method of the intensifier of this comparative example, the raw material ratio of seawater sea-sand concrete, and the preparation method of seawater sea-sand concrete are all the same as those of Example 1.

[0116] Comparative Example 5

[0117] The difference between the intensifier of this comparative example and that of Example 1 is only that: no surfactant is added; the rest are the same as those of Example 1.

[0118] That is, by weight, the intensifier of this comparative example includes: 40 parts of modified polymer (prepared in the same way as in Example 1), 30 parts of nano-silica sol, 15 parts of nano-aluminum sol, and 30 parts of water.

[0119] The difference between the preparation method of the intensifier of this comparative example and that of Example 1 is only that: the step of adding surfactant is omitted; the rest are the same as those of Example 1.

[0120] The raw material ratio of seawater sea-sand concrete and the preparation method of seawater sea-sand concrete of this comparative example are both the same as those of Example 1.

[0121] Comparative Example 6

[0122] The difference between the enhancer of this comparative example and that of Example 1 lies only in that: the modified polymer used is different from that of Example 1 (when preparing the modified polymer, the silane modification step is omitted and polyetheramine grafting is directly carried out; that is, step S2 is omitted when preparing the modified polymer); the rest are the same as those of Example 1.

[0123] The raw material ratio of the enhancer of this comparative example, the preparation method of the enhancer, the raw material ratio of the seawater sea sand concrete, and the preparation method of the seawater sea sand concrete are all the same as those of Example 1.

[0124] Comparative Example 7

[0125] The difference between the seawater sea sand concrete of this comparative example and that of Example 1 lies only in that: the self-adaptive enhancer for the seawater sea sand concrete is omitted; the rest are the same as those of Example 1.

[0126] Experimental Example

[0127] 1. The seawater sea sand concrete specimens cast in the above examples and comparative examples were cured in seawater at 45°C for 28 days and 100 days, and then the performance indicators were tested according to GB / T50082-2009. The results are shown in Table 1 below:

[0128] Table 1

[0129]

[0130] In Table 1, the "lifting ratio of compressive strength compared with 28d" refers to the lifting ratio of the 100d compressive strength of the same seawater sea sand concrete relative to its 28d compressive strength; it is calculated according to "(100d compressive strength - 28d compressive strength) / 28d compressive strength × 100%";

[0131] The "lifting ratio of 100d compressive strength" refers to the lifting ratio of the 100d compressive strength of the concrete of other examples or comparative examples calculated based on the 100d compressive strength of Comparative Example 7, and is calculated according to "(100d compressive strength of examples or comparative examples other than Comparative Example 7 - 100d compressive strength of Comparative Example 7) / 100d compressive strength of Comparative Example 7 × 100%";

[0132] The "crack self-healing rate" is the test result at the time of curing for 100 days, and is tested according to the method of "9 Early Anti-cracking Test" in the standard of GB / T50082-2009;

[0133] The calculation method of the "lifting ratio of crack self-healing rate": based on the crack self-healing rate of Comparative Example 7, it is calculated according to '(crack self-healing rate of examples or comparative examples other than Comparative Example 7 - crack self-healing rate of Comparative Example 7) / crack self-healing rate of Comparative Example 7 × 100%'.

[0134] As can be seen from Table 1, the dispersing and bonding effects of the modified polymer are lacking in the intensifier of Comparative Example 1, resulting in a significant reduction in the performance of the concrete; in the intensifier of Comparative Example 2, due to the excessive amount of the modified polymer, the workability of the concrete becomes poor and the strength development is affected; in the intensifier of Comparative Example 3, due to the excessive amount of nano-silica sol, the balance of the system is destroyed, leading to a performance decline; in the intensifier of Comparative Example 4, due to the excessive amount of nano-aluminum sol, the balance of the Al-O-Si network structure is destroyed, resulting in a performance decline; in the intensifier of Comparative Example 5, due to the lack of the dispersing effect of the surfactant, the workability of the concrete is poor and the compactness is reduced, resulting in non-compliant performance; in the intensifier of Comparative Example 5, due to the lack of silane groups, good chemical bonding cannot be formed with the cement hydration products, leading to a reduction in the strengthening effect.

[0135] 2. SEM Observation

[0136] The microstructures of the seawater and sea sand concrete of Example 1 and Comparative Example 7 after curing in seawater at 45°C for 100 days were observed respectively; the SEM images are as Figure 3 shown.

[0137] Figure 3 In the figure: the left figure is the microstructure of Comparative Example 7. After soaking in seawater at 45°C for 100 days, there are multiple cracks in the concrete matrix and the number of harmful pores increases; the right figure is the microstructure of the seawater and sea sand concrete of Example 1. After soaking in seawater at 45°C for 100 days, the concrete matrix is denser and the self-adaptive intensifier repairs the cracks that appear.

[0138] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An adaptive enhancer for seawater and sea sand concrete, characterized in that, By weight parts, it includes the following components: 20 - 40 parts of modified polymer, 15 - 30 parts of nano-silica sol, 8 - 15 parts of nano-alumina sol, 2 - 5 parts of surfactant, and 10 - 30 parts of water; The modified polymer is prepared by a method including the following steps: S1. Mix acrylic acid monomer, initiator, and chain transfer agent, and carry out free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2. Mix γ-aminopropyltrimethoxysilane, solvent, and the polyacrylic acid main chain, heat up and stir to react, and then carry out vacuum distillation to obtain a silane-modified product; S3. Carry out grafting reaction between the silane-modified product and polyetheramine to obtain the modified polymer.

2. The self-adaptive enhancer for seawater and sea sand concrete according to claim 1, wherein, In step S1, the molar ratio of the acrylic acid monomer, initiator, and chain transfer agent is (100 - 120):(1 - 5):(0.5 - 3); the temperature of the free radical polymerization reaction is 70 ± 5 °C, and the reaction time is 4 - 6 h; In step S2, the molar ratio of γ-aminopropyltrimethoxysilane and polyacrylic acid main chain is (15 - 25):1, and the molar ratio of solvent and polyacrylic acid main chain is (1 - 4):1; heat up to 120 ± 5 °C and stir to react for 3 - 5 h; In step S3, the molar ratio of the silane-modified product and polyetheramine is 1:(8 - 12); the temperature of the grafting reaction is 80 ± 5 °C, and the time is 2 - 4 h.

3. The self-adaptive enhancer for seawater and sea sand concrete according to claim 1, characterized in that The surfactant is at least one of polycarboxylate superplasticizer, naphthalene superplasticizer, and amino sulfonate superplasticizer.

4. The preparation method of the self-adaptive enhancer for seawater and sea sand concrete according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Dissolve the modified polymer in water to prepare a 15% - 20% modified polymer solution; (2) Add the nano-silica sol to the modified polymer solution under stirring conditions; (3) Continue to stir and dropwise add the nano-alumina sol; (4) Add surfactant and carry out ultrasonic dispersion; (5) Adjust the pH to 7 - 8, and carry out static stabilization to obtain the self-adaptive enhancer for seawater and sea sand concrete.

5. The preparation method of the self-adaptive enhancer for seawater and sea sand concrete according to claim 4, characterized in that In step (2), the stirring speed is 200 - 300 rpm, and the temperature is 25 - 30 °C; In step (4), the ultrasonic power is 300 - 500 W, the frequency is 20 - 40 kHz, and the ultrasonic dispersion time is 15 - 20 min; In step (5), the temperature for static stabilization is 20 - 30 °C, the time for static stabilization is 12 - 36 h, and the static stabilization is carried out in an environment with relative humidity ≤ 65%; 6. A seawater and sea sand concrete, characterized in that, The components of the seawater and sea sand concrete include the self-adaptive enhancer for seawater and sea sand concrete as described in any one of claims 1 - 3, seawater, and sea sand.

7. The seawater and sea sand concrete according to claim 6, characterized in that By weight parts, the seawater and sea sand concrete includes the following components: 100 parts of cement, 150 - 180 parts of sea sand, 200 - 240 parts of crushed stone, 3 - 8 parts of the self-adaptive enhancer for seawater and sea sand concrete as described in any one of claims 1 - 3, and 35 - 45 parts of seawater.

8. The seawater and sea sand concrete according to claim 7, wherein, The fineness modulus of the sea sand is 2.3 - 3.0, the mud content is less than 3%, the shell content is less than 3%, and the chloride ion content is less than 0.06%; The particle size of the crushed stone is 5 - 20 mm, the mud content is less than 1%, and the content of needle-like and flaky particles is less than 10%. The cement is ordinary Portland cement with a strength grade not lower than 42.

5.

9. The preparation method of seawater and sea sand concrete according to any one of claims 7-8, characterized in that, It includes the following steps: I. Mix the cement, sea sand, crushed stone, the self-adaptive enhancer for seawater sea sand concrete as described in any one of claims 1 - 3, and seawater to obtain a mixture; II. Stir the mixture evenly, pour it into a mold, and cure the molded part.

10. The preparation method of seawater and sea sand concrete according to claim 9, characterized in that, The preparation of the seawater sea sand concrete is carried out under the following environment: the temperature is 20 - 30 °C, and the relative humidity is 60% - 80%; The curing conditions are: soak the molded part in seawater at 40 - 50 °C for curing.

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