Self-adaptive reinforcing agent for seawater and sea sand concrete as well as preparation method and application of self-adaptive reinforcing agent

Abstract

The invention belongs to the technical field of concrete, and particularly relates to a self-adaptive reinforcing agent for seawater and sea sand concrete as well as a preparation method and application of the self-adaptive reinforcing agent. The self-adaptive reinforcing agent disclosed by the invention is prepared from the following components in parts by weight: 20 to 40 parts of modified polymer, 15 to 30 parts of nano silica sol, 8 to 15 parts of nano aluminum sol, 2 to 5 parts of surfactant and 10 to 30 parts of water, the modified polymer is prepared from an acrylic monomer through silane modification and polyether amine grafting. The modified polymer in the self-adaptive reinforcing agent for the seawater and sea sand concrete ensures the stability in a seawater environment through a special molecular structure design; an Al-O-Si network formed by the nano silica sol and the nano aluminum sol provides structural enhancement; due to the synergistic effect of multiple components, the self-adaptive enhancement effect is achieved; and meanwhile, the dispersity and compatibility of the reinforcing agent are optimized by introducing the surfactant.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and in particular relates to an adaptive reinforcing agent for seawater and sea sand concrete, and a preparation method and 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 the advantages of abundant reserves and convenient mining, but its high salt content and poor particle morphology seriously restrict its application in concrete. At the same time, due to the increasing shortage of freshwater resources, the demand for using seawater to mix concrete is becoming increasingly urgent. However, seawater and sea sand concrete faces serious problems such as accelerated chloride ion erosion, steel bar corrosion, and poor interface bonding, which seriously affect the service life of concrete structures.

[0003] At present, the main method to improve the performance of seawater and sea sand concrete is to reduce the salt content of sea sand by rinsing with fresh water, but this method not only consumes a lot of fresh water resources, but also causes secondary pollution; in addition, the sea sand after rinsing is easy to get damp 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 increase the density of concrete, but this method often reduces the early strength of concrete, affects the construction progress, and in the seawater environment, the activity of the admixture is easily inhibited. In addition, there are also methods of using admixtures to adjust the working performance of concrete, but traditional admixtures are prone to failure in high-salt environments, lack continuous reinforcement, and cannot cope with performance fluctuations caused by changes in environmental conditions.

[0004] Especially in complex marine environments, the performance of concrete will degrade with changes in environmental conditions such as temperature, humidity, and salinity, and may even cause strength shrinkage, expansion, and cracking. Existing technologies make it difficult to achieve adaptive adjustment of concrete performance.

[0005] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0006] The object of the present invention is to provide an adaptive reinforcing agent for seawater and sea sand concrete, and a preparation method and application thereof, so as to help solve or improve the problem of poor durability that concrete used in marine environments is prone to.

[0007] In order to achieve the above-mentioned purpose, the present invention provides the following technical scheme: an adaptive reinforcing agent for seawater and sea sand concrete, comprising 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 a method comprising the following steps: S1, mixing an acrylic acid monomer, an initiator and a chain transfer agent, and performing free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2, mixing γ-aminopropyltrimethoxysilane, a solvent and the polyacrylic acid main chain, heating and stirring to react, and then distilling under reduced pressure to obtain a silane-modified product; S3, performing a grafting reaction on the silane-modified product and a polyetheramine to obtain the modified polymer.

[0008] Preferably, in step S1, the molar ratio of the acrylic acid monomer, the initiator and the 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 4-6h; 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; the temperature is raised to 120±5°C, and the reaction is stirred for 3-5h; in step S3, the molar ratio of the silane-modified product to the polyetheramine is 1:(8-12); the temperature of the grafting reaction is 80±5°C, and the reaction time is 2-4h.

[0009] Preferably, the surfactant is at least one of a polycarboxylic acid-based water reducer, a naphthalene-based water reducer and an aminosulfonic acid-based water reducer.

[0010] The present invention also provides a method for preparing an adaptive reinforcing agent for seawater and sea sand concrete, which adopts the following technical scheme: the method for preparing an adaptive reinforcing agent for seawater and sea sand concrete as described above comprises the following steps: (1) dissolving the modified polymer in water to prepare a 15%-20% modified polymer solution; (2) adding the nano silica sol to the modified polymer solution under stirring; (3) continuing to stir and dripping the nano aluminum sol; (4) adding a surfactant and ultrasonically dispersing; (5) adjusting the pH to 7-8 and standing for stabilization to obtain the adaptive reinforcing agent 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 of ≤65%.

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

[0013] Preferably, the seawater and sea sand concrete comprises the following components in parts by weight: 100 parts of cement, 150-180 parts of sea sand, 200-240 parts of crushed stone, 3-8 parts of the adaptive reinforcing agent 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 gravel 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, and the strength grade is not less than 42.5.

[0015] The present invention also provides a method for preparing the seawater and sea sand concrete as described above, which adopts the following technical scheme: The method for preparing the seawater and sea sand concrete comprises the following steps: I. Mixing the cement, sea sand, gravel, the adaptive reinforcing agent for seawater and sea sand concrete as described above and seawater to obtain a mixture; II. Stirring the mixture evenly, casting and molding, and curing the molded parts.

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

[0017] Beneficial effects:

[0018] (1) The present invention innovatively combines modified polymers with nanosols to design and develop a new type of adaptive reinforcing agent. The modified polymer in the adaptive reinforcing agent for seawater sand concrete of the present invention ensures stability in seawater environment through special molecular structure design; the Al-O-Si network formed by nano-silica sol and nano-aluminum sol provides structural reinforcement; the synergistic effect of multiple components produces an adaptive reinforcement effect; at the same time, the introduction of surfactants optimizes the dispersibility and compatibility of the reinforcing agent; this design concept provides a new technical route for solving the durability problem of seawater sand concrete.

[0019] (2) The modified polymer in the adaptive enhancer of the present invention adopts a unique multi-level molecular design: the main chain is a carboxylated polyacrylic acid skeleton, and the introduction of silane groups allows the modified polymer to achieve chemical bonding with cement hydration products, while the grafting of the amino terminal provides pH responsiveness; this multifunctional molecular structure enables the material to remain stable in a seawater environment, while automatically adjusting the degree of ionization as the environment changes, thereby achieving 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, establishes a rigid skeleton through the formation of Al-O-Si bonds, fills the pores between cement hydration products, and significantly improves the mechanical properties of the concrete (for example, the adaptive reinforcing agent for seawater and sea sand concrete of the present invention can make the 28-day compressive strength of the concrete ≥50MPa, the 100-day compressive strength is increased by more than 10% compared with 28 days, and the crack self-repair rate exceeds 90%).

[0021] (4) The adaptive reinforcing agent for seawater sand concrete of the present invention has a significant ion balance regulating ability: in a high-salt environment, the carboxyl group of the modified polymer can react with Ca 2+ Form chelates to reduce free Ca 2+ concentration; the hydroxyl groups on the surface of the nanosol can fix Cl by ion exchange - , forming a stable electrical double-layer structure; this synergistic effect makes the compressive strength of the concrete after 100 days of immersion more than 30% better than that of seawater and sea sand concrete with the same proportion but without the addition of adaptive reinforcing agent.

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

[0023] (6) The seawater and sea sand concrete of the present invention exhibits excellent comprehensive performance: it has good mechanical properties and durability (for example, the self-repair rate of cracks after 100 days of immersion can be increased by more than 50% compared with the seawater and sea sand concrete of the same proportion without adding adaptive reinforcing agent), which makes it have broad application prospects in marine engineering, port terminals, cross-sea bridges, offshore wind power and other projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary 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 This is a schematic diagram of the molecular structure of the adaptive reinforcing agent for seawater and sea sand concrete provided in Example 1 of the present invention.

[0026] Figure 2 Schematic diagram of the structure of seawater and sea sand concrete after immersion for 100 days; among them, (a) is seawater and sea sand concrete without adding reinforcing agent; (b) is seawater and sea sand concrete with adding adaptive reinforcing agent.

[0027] Figure 3 These are SEM images of the microstructure of the seawater and sea sand concrete of Example 1 and Comparative Example 7 of the present invention; wherein, the left image is the SEM image of the seawater and sea sand concrete of Comparative Example 7; and the right image is the SEM image of the interface transition zone structure and the reinforced product of the seawater and sea sand concrete of Example 1. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention 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 the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0030] The present invention aims to solve the problem of poor durability of concrete currently used in marine environment (for example, performance degradation, strength shrinkage or expansion cracking of concrete as environmental conditions change), and provides an adaptive reinforcing agent for seawater and sea sand concrete.

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

[0032] The self-adaptive reinforcing agent for seawater and sea sand concrete of the present invention comprises the following components by weight: 20-40 parts (for example, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts) of a modified polymer, 15-30 parts (for example, 15 parts, 18 parts, 21 parts, 24 parts, 27 parts or 30 parts) of a nano silica sol, 8-15 parts (for example, 8 parts, 10 parts, 12 parts, 14 parts or 15 parts) of a nano aluminum sol, 2-5 parts (for example, 2 parts, 3 parts, 4 parts or 5 parts) of a surfactant and 10- 30 parts (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, mixing acrylic acid monomer, initiator and chain transfer agent, and performing free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2, mixing γ-aminopropyltrimethoxysilane, solvent and polyacrylic acid main chain, heating and stirring to react, and then distilling under reduced pressure to obtain a silane-modified product; S3, grafting the silane-modified product with polyetheramine to obtain a modified polymer. 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: forming a chemical bond with cement hydration products through the silane group (alkoxy can react with cement hydration products), providing pH responsiveness through the amino group, and participating in the formation of a multifunctional molecular structure of the modified polymer (having an appropriate carbon chain length to help ensure the flexibility of the modified polymer molecule); 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 between it and the cement hydration product.

[0039] The modified polymer in the adaptive reinforcing agent for seawater and sea sand concrete of the present invention is a multifunctional macromolecule, which can achieve the following functions through special molecular design (refer to Figure 1-2): The carboxylation main chain provides dispersibility, the silane group realizes chemical bonding, and the amino terminal provides pH responsiveness; this structure of the modified polymer enables it to exhibit excellent adaptive performance in seawater environment; the synergistic effect of nano-silica sol and nano-alumina sol enables it to construct 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, significantly improving the mechanical properties of concrete; the reinforcing agent of the present invention has a significant ability to regulate ion balance. In a high-salt environment, the carboxyl group of the modified polymer can react with Ca 2+ Form chelates to reduce free Ca 2+ concentration; the hydroxyl groups on the surface of the nanosol can fix Cl by ion exchange - , forming a stable electrical double-layer structure; the adaptive reinforcing agent system for seawater and sea sand concrete of the present invention has multiple action mechanisms: achieving uniform dispersion of cement particles through electrostatic and stereo effects (synergistic effect of surfactant and modified polymer; wherein, the carboxylation main chain of the modified polymer helps to provide dispersion performance, and the multi-level molecular structure helps to provide stereo stability), improving the workability of concrete; forming a nano-scale transition layer on the aggregate surface to improve the interface bonding performance; providing multi-scale reinforcement effects through an inorganic-organic hybrid network; being able to automatically adjust system performance according to environmental conditions to maintain long-term stability (such as Figure 2 As shown, Figure 2 (a) is a concrete matrix into which the adaptive reinforcing agent of the present invention is added, and (b) is a seawater and sea sand concrete matrix into which the adaptive reinforcing agent of the present invention is not added; after adding the adaptive reinforcing agent of the present invention, the concrete matrix has the effect of adaptive reinforcement, with smaller pores and higher crack self-repairing ability).

[0040] The adaptive reinforcing agent for seawater and sea sand concrete of the present invention has excellent adaptive performance and reinforcing effect, can significantly improve the mechanical properties and durability of seawater and sea sand concrete, and has broad application prospects in marine engineering, port terminals, cross-sea bridges, offshore wind power and other projects.

[0041] In a preferred embodiment of the adaptive reinforcing agent for seawater and sea sand concrete of the present invention, in step S1, the molar ratio of acrylic acid 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 ( The molar ratio of the solvent to the polyacrylic acid backbone is (1-4):1 (e.g., 1:1, 2:1, 3:1 or 4:1), the temperature is raised to 120±5°C (e.g., 115°C, 118°C, 120°C or 125°C), and the reaction is stirred for 3-5h (e.g., 3h, 3.5h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 15:1, 18:1, 20:1, 22:1 or 25:1), the molar ratio of the solvent to the polyacrylic acid backbone is (1-4):1 (e.g., 1:1, 2:1, 3:1 or 4:1), the h, 4.5h or 5h); in step S3, the molar ratio of the silane-modified product to the 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 2-4h (for example, 2h, 2.5h, 3h, 3.5h or 5h). Among them, if the proportion of γ-aminopropyltrimethoxysilane is too large (for example, >25:1), the adverse effects are: (1) Product: excessive silane groups will lead to excessive crosslinking; the solubility of the modified polymer is reduced, the molecular structure is too rigid, and the flexibility is reduced; (2) Performance: adaptive performance is reduced, pH response ability is weakened; dispersion compatibility with cement particles is deteriorated; local silane enrichment areas may be formed, affecting uniformity; increasing material costs; (3) Process: increased viscosity of the reaction system; increased difficulty in product processing; and more side reactions may occur. If the proportion of γ-aminopropyltrimethoxysilane is too small (for example, <15:1), the adverse effects are: (1) Product: insufficient silane modification, insufficient chemical bonding sites, and incomplete network structure formation; (2) Performance: insufficient chemical bonding with cement hydration products, significantly reduced strengthening effect, limited adaptive adjustment ability, and reduced durability; (3) Application effect: limited concrete strength development, poor interface bonding performance, reduced crack resistance, and insufficient self-repairing ability.If the amount of polyetheramine used in step S3 is too large, the final product will be too hydrophilic, affecting its compatibility with the cement system, and too much free polyetheramine may interfere with the cement hydration process; if the amount of polyetheramine used is too small, due to incomplete grafting reaction, the number of pH response groups in the product is insufficient, and the expected adaptive adjustment function cannot be achieved; after systematic research, the molar ratio of silane-modified product to polyetheramine is most suitable in the range of 1: (8-12), at this time, a modified polymer with complete structure and excellent performance can be obtained, ensuring that it plays an ideal reinforcement 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 thioglycolic acid, mercaptopropionic acid, mercaptoethanol and mercaptan.

[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 adaptive reinforcing agent for seawater and sea sand concrete of the present invention, the surfactant is at least one of a polycarboxylic acid water reducer, a naphthalene water reducer and an aminosulfonic acid water reducer. The polycarboxylic acid water reducer can provide a steric exclusion effect, while the naphthalene water reducer and the aminosulfonic acid water reducer can provide an electrostatic repulsion effect.

[0045] The present invention also proposes a method for preparing the self-adaptive reinforcing agent for seawater and sea sand concrete as described above. The method for preparing the self-adaptive reinforcing agent for seawater and sea sand concrete according to the embodiment of the present invention comprises the following steps: (1) dissolving a modified polymer in water to prepare a 15%-20% (for example, 15%, 16%, 17%, 18%, 19% or 20%) modified polymer solution; (2) adding nano-silica sol to the modified polymer solution under stirring conditions; (3) continuing to stir and adding nano-aluminum sol dropwise; (4) adding a surfactant and ultrasonically dispersing; (5) adjusting the pH to 7-8 (for example, 7, 7.2, 7.4, 7.6, 7.8 or 8), standing and stabilizing, and obtaining the self-adaptive reinforcing agent for seawater and sea sand concrete. Among them, the ultrasonic dispersion step can not only achieve uniform mixing of the components, but more importantly, through the ultrasonic cavitation effect: (1) effectively break the agglomeration of the nanosol and promote its uniform dispersion with the modified polymer; (2) enhance the dispersion effect of the surfactant to form a stable colloidal system; (3) promote the interaction between the modified polymer and the nanosol and optimize the interface structure; (4) help to form a more uniform three-dimensional network structure and improve product performance. In step (5), if the pH is adjusted to pH>8, the following adverse effects will occur: excessive ionization of the amino group in the modified polymer will lead to changes in molecular conformation; the stability of the nanosol will decrease and it will easily coagulate; the viscosity of the system will increase, which is not conducive to engineering applications; it may accelerate cement hydration and affect the workability of concrete. If the pH is adjusted to pH<7, the following adverse effects will occur: the pH response ability of the modified polymer is limited; the dispersibility of the nanosol becomes poor; the formation of the Al-O-Si network structure is hindered; the stability of the system is reduced and phase separation is easy to occur; and the compatibility with the cement system is poor.

[0046] In addition, the order of adding the components in the present invention has a significant impact on the product performance: the advantages of the correct order (modified polymer solution → nano silica sol → nano aluminum sol → surfactant): ensure that the modified polymer is fully dissolved; it is conducive to the gradual dispersion of the nano sol; it promotes the orderly formation of the Al-O-Si network; the surfactant can ultimately optimize the dispersion effect. The wrong order may lead to: nano sol agglomeration, uneven dispersion of the modified polymer, incomplete network structure, poor system stability, and reduced enhancement effect; in particular, if the nano aluminum sol is added first, it is easy to form agglomerates with the modified polymer, affecting the subsequent dispersion of the nano silica sol, which is 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 the nano sol, and reduce the dispersion enhancement effect.

[0047] Preferably, in step (5), the temperature of the static stabilization is 20-30°C (for example, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C), the static stabilization time is 12-36h (for example, 12h, 16h, 20h, 25h, 30h or 36h), and the static stabilization is carried out in an environment with a relative humidity of ≤65%. If the temperature is too high (>30°C), the system maturation will be accelerated, which may cause component separation and affect product stability; if the temperature is too low (<20°C), the stabilization process will be prolonged, the interaction between components will be insufficient, and the final performance will be affected; if the static stabilization time is too short (<12 hours), the system will not reach full balance, the stability will be insufficient, and the performance will be unstable; if the static stabilization time is too long (>36 hours), the production cycle will be increased, and component sedimentation may occur, which is not economical; by controlling the humidity of the environment during static stabilization, it is helpful to avoid concentration changes and product performance fluctuations due to water evaporation.

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

[0049] The present invention also proposes a seawater and sea-sand concrete. The components of the seawater and sea-sand concrete in the embodiment of the present invention include the adaptive reinforcing agent for seawater and 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, the seawater and sea sand concrete includes the following components, measured by weight: 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 adaptive reinforcer 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, if the amount of adaptive enhancer is too large (for example, >8 parts), the adverse effects are: (1) Impact on the performance of fresh concrete: the slump is too large, resulting in poor workability, difficulty in controlling fluidity, increased risk of water seepage and segregation, and too long initial setting time; (2) Impact on mechanical properties: strength development is hindered, elastic modulus is reduced, interface bonding effect is poor, and internal defects increase. (3) Impact on durability: increased risk of shrinkage cracking, reduced impermeability, increased chloride ion permeability, and poor long-term stability; (4) Other aspects: increased project costs, affected construction progress, and reduced environmental friendliness. If the amount of adaptive enhancer is too small (for example, <3 parts), the adverse effects are: (1) Insufficient enhancement effect: limited improvement in compressive strength, poor crack resistance, insufficient self-repairing ability, and unclear interface enhancement effect; (2) Durability issues: weak resistance to chloride ion penetration, poor resistance to seawater erosion, insufficient adaptive adjustment ability, and rapid long-term performance degradation; (3) Microstructural defects: high porosity, loose structure in the interface transition zone, incomplete three-dimensional network structure, and low crack self-repair rate; (4) Impact on engineering applications: unable to meet the durability requirements of marine engineering, shortened service life, and increased maintenance costs. The advantages of using the adaptive reinforcing agent within the optimal dosage range (3-8 parts) are as follows: (1) Performance optimization: reasonable strength development, good working performance, dense interface structure, and strong self-repairing ability; (2) Durability guarantee: low chloride ion permeability coefficient, good resistance to seawater erosion, strong adaptive adjustment ability, and stable long-term performance; (3) Economic rationality: optimal cost-effectiveness, convenient construction, and low maintenance costs. Therefore, a large number of experimental studies and engineering practices have proved that it is most reasonable to control the dosage of the adaptive reinforcing agent within the range of 3-8 parts, which can ensure that seawater sand concrete obtains ideal comprehensive performance.

[0051] Preferably, the amount of the adaptive enhancer is 5-6 parts, at which 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 stone, 40 parts of sea water and 3-8 parts of adaptive reinforcer; or, the seawater and sea-sand concrete comprises 100 parts of cement, 160 parts of sea sand, 210 parts of crushed stone, 38 parts of sea water and 3-8 parts of adaptive reinforcer; or, the seawater and sea-sand concrete comprises 100 parts of cement, 170 parts of sea sand, 225 parts of crushed stone, 42 parts of sea water and 3-8 parts of adaptive reinforcer; or, the seawater and sea-sand concrete comprises 100 parts of cement, 175 parts of sea sand, 230 parts of crushed stone, 43 parts of sea water and 3-8 parts of adaptive reinforcer; or, the seawater and sea-sand concrete comprises 100 parts of cement, 155 parts of sea sand, 215 parts of crushed stone, 37 parts of sea water and 3-8 parts of adaptive reinforcer;

[0053] Or, seawater and sea sand concrete includes 100 parts of cement, 180 parts of sea sand, 235 parts of crushed stone, 45 parts of seawater and 3-8 parts of 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 stone is 5-20 mm, the mud content is less than 1%, and the needle-like particle content is less than 10%; the cement is ordinary Portland cement, and the strength grade is not less than 42.5; the seawater is obtained by filtering natural seawater (it is sufficient to remove obvious impurities in the natural seawater).

[0055] The present invention also proposes a method for preparing the seawater and sea sand concrete as described above. The method for preparing the seawater and sea sand concrete in an embodiment of the present invention comprises the following steps: I. mixing cement, sea sand, gravel, the adaptive reinforcing agent for seawater and sea sand concrete as described above, and seawater to obtain a mixture; II. stirring the mixture evenly, casting and molding, and curing the molded parts.

[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 following is a detailed description of the self-adaptive reinforcing agent for seawater and sea sand concrete of the present invention and its preparation method and application 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 method for preparing seawater and sea sand concrete of the present embodiment comprises the following steps: 1. mixing cement, sea sand, crushed stone, the adaptive reinforcing agent of the present embodiment and seawater to obtain a mixture;

[0074] II. Stir the mixture evenly, cast and shape the sample, and cure the sample after shaping (immerse in 45°C seawater for curing). The preparation of seawater sand concrete in this embodiment is carried out under the environment of 20-30°C and relative humidity of 60%-80% (before curing).

[0075] Example 2

[0076] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment includes, by weight: 20 parts of modified polymer, 15 parts of nano silica sol, 8 parts of nano aluminum sol, 2 parts of surfactant and 10 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 and naphthalene water reducer (the mass ratio of the two is 3:1), and includes, by weight: 1.5 parts of polycarboxylic acid water reducer and 0.5 parts of naphthalene water reducer.

[0077] 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.

[0078] 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, 3 parts of the adaptive enhancer of this embodiment, and 40 parts of seawater.

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

[0080] Example 3

[0081] The adaptive reinforcing agent for seawater and sea sand concrete of this embodiment comprises, by weight: 30 parts of modified polymer, 25 parts of nano silica sol, 12 parts of nano aluminum sol, 4 parts of surfactant and 20 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 2:1:1), and comprises, by weight: 2 parts of polycarboxylic acid water reducer, 1 part of naphthalene water reducer and 1 part of aminosulfonic acid water reducer.

[0082] 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.

[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 only difference between the reinforcing agent in this comparative example and that in Example 1 is that the dosage of the nano-silica sol is increased to 40 parts; the rest is the same as in Example 1.

[0110] That is, in parts by weight, the reinforcing agent of this comparative example includes: 40 parts of modified polymer (prepared by the same method 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 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.

[0112] Comparative Example 4

[0113] The only difference between the reinforcing agent in this comparative example and that in Example 1 is that the dosage of the nano aluminum sol is increased to 20 parts; the rest is consistent with that in Example 1.

[0114] That is, by weight, the reinforcing agent of this comparative example includes: 40 parts of modified polymer (prepared by the same method 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 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.

[0116] Comparative Example 5

[0117] The enhancer in this comparative example is different from that in Example 1 only in that no surfactant is added; the rest is the same as in Example 1.

[0118] That is, by weight, the reinforcing agent of this comparative example includes: 40 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 and 30 parts of water.

[0119] The preparation method of the enhancer in this comparative example is different from that in Example 1 only in that the step of adding a surfactant is omitted; the rest is the same as in Example 1.

[0120] 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.

[0121] Comparative Example 6

[0122] The reinforcing agent of this comparative example is different from that of Example 1 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 performed; that is, step S2 is omitted when preparing the modified polymer); the rest is consistent with Example 1.

[0123] The raw material ratio of the reinforcing agent, 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.

[0124] Comparative Example 7

[0125] The seawater and sea sand concrete of this comparative example is different from that of Example 1 only in that the adaptive reinforcing agent used for the seawater and sea sand concrete is omitted; the rest is consistent with Example 1.

[0126] Experimental example

[0127] 1. The seawater and sea sand concrete casting specimens of the above embodiment and comparative example were cured in 45°C seawater 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 increase ratio of compressive strength compared with 28d" refers to the increase ratio of the 100d compressive strength of the same seawater sand concrete relative to its 28d compressive strength; it is calculated according to "(100d compressive strength - 28d compressive strength) / 28d compressive strength × 100%";

[0131] “100d compressive strength improvement ratio” means the improvement ratio of the 100d compressive strength of concrete of other embodiments or comparative examples calculated based on the 100d compressive strength of comparative example 7, which is calculated according to “(100d compressive strength of embodiments or comparative examples other than comparative example 7 - 100d compressive strength of comparative example 7) / 100d compressive strength of comparative example 7 × 100%”;

[0132] "Crack self-repair rate" is the test result after 100 days of curing, and is tested according to the method of "9 Early crack resistance test" in GB / T50082-2009 standard;

[0133] Calculation method for "crack self-repair rate improvement ratio": based on the crack self-repair rate of comparative example 7, it is calculated according to '(crack self-repair rate of embodiments or comparative examples other than comparative example 7 - crack self-repair rate of comparative example 7) / crack self-repair rate of comparative example 7 × 100%'.

[0134] It can be seen from Table 1 that the reinforcing agent of Comparative Example 1 lacks the dispersing and bonding effects of the modified polymer, and the performance of the concrete is significantly reduced; the reinforcing agent in Comparative Example 2 has an excessive amount of modified polymer, which leads to poor workability of the concrete and affects the strength development; the reinforcing agent in Comparative Example 3 has an excessive amount of nano-silica sol, which destroys the balance of the system and leads to a decrease in performance; the reinforcing agent in Comparative Example 4 has an excessive amount of nano-aluminum sol, which destroys the balance of the Al-O-Si network structure and leads to a decrease in performance; the reinforcing agent in Comparative Example 5 lacks the dispersing effect of the surfactant, the concrete workability is poor, the density is reduced, and the performance does not meet the standard; the reinforcing agent in Comparative Example 5 lacks silane groups and cannot form a good chemical bond with the cement hydration product, resulting in a reduced reinforcement effect.

[0135] 2. SEM observation

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

[0137] Figure 3 Middle: The left picture shows the microstructure of comparative example 7. After being immersed in seawater at 45°C for 100 days, multiple cracks appeared in the concrete matrix and the number of harmful holes increased. The right picture shows the microstructure of the seawater and sea sand concrete of Example 1. After being immersed in seawater at 45°C for 100 days, the concrete matrix became more compact and the adaptive reinforcing agent repaired the cracks that appeared.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An adaptive reinforcing agent for seawater and sea sand concrete, characterized in that: By weight, it includes 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, mixing acrylic acid monomer, initiator and chain transfer agent, and performing free radical polymerization under nitrogen protection to obtain a polyacrylic acid main chain; S2, mixing γ-aminopropyltrimethoxysilane, a solvent and the polyacrylic acid main chain, heating and stirring to react, and then distilling under reduced pressure to obtain a silane-modified product; S3, subjecting the silane-modified product to a grafting reaction with a polyetheramine to obtain the modified polymer.

2. The self-adaptive reinforcing agent for seawater and sea sand concrete according to claim 1, characterized in that: In step S1, the molar ratio of the acrylic acid monomer, the initiator and the 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 hours; 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; heating to 120±5° C., stirring and reacting for 3-5 hours; In step S3, the molar ratio of the silane-modified product to the polyetheramine is 1:(8-12); the temperature of the grafting reaction is 80±5° C., and the time is 2-4 hours.

3. The self-adaptive reinforcing agent for seawater and sea sand concrete according to claim 1, characterized in that: The surfactant is at least one of a polycarboxylic acid water reducer, a naphthalene water reducer and an aminosulfonic acid water reducer.

4. The method for preparing the adaptive reinforcing agent for seawater and sea sand concrete according to any one of claims 1 to 3, characterized in that: The steps include: (1) dissolving the modified polymer in water to prepare a 15%-20% modified polymer solution; (2) adding the nano-silica sol to the modified polymer solution under stirring; (3) continuing to stir and adding the nano aluminum sol dropwise; (4) adding a surfactant and performing ultrasonic dispersion; (5) adjusting the pH to 7-8 and allowing to stand for stabilization to obtain the self-adaptive enhancer for seawater and sea sand concrete.

5. The method for preparing the adaptive reinforcing agent 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 power of the ultrasound 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 hours, and the static stabilization is carried out in an environment with a relative humidity of ≤65%.

6. A seawater and sea sand concrete, characterized in that: The components of the seawater and sea-sand concrete include the adaptive reinforcing agent for seawater and sea-sand concrete as described in any one of claims 1 to 3, seawater and sea sand.

7. The seawater and sea sand concrete according to claim 6, characterized in that: The seawater and sea-sand concrete comprises the following components by weight: 100 parts of cement, 150-180 parts of sea sand, 200-240 parts of crushed stone, 3-8 parts of the adaptive reinforcing agent 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 6, characterized in that: The sea sand has a fineness modulus of 2.3-3.0, a mud content of less than 3%, a shell content of less than 3%, and a chloride ion content of less than 0.06%; The crushed stone has a particle size of 5-20 mm, a mud content of less than 1%, and a needle-like particle content of less than 10%; The cement is ordinary Portland cement with a strength grade of not less than 42.

5.

9. The method for preparing seawater and sea sand concrete according to any one of claims 6 to 8, characterized in that: The steps include:

1. Mixing the cement, sea sand, crushed stone, the adaptive reinforcing agent for seawater and sea sand concrete according to any one of claims 1 to 3, and seawater to obtain a mixture; II. Stir the mixture evenly, cast it into shape, and cure the molded part.

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

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