Environment-friendly cement-based composite material for dredged materials and preparation method thereof

Abstract

The application provides an environmental-friendly cement-based composite material of dredged material and a preparation method thereof, and belongs to the technical field of waste utilization. The environmental-friendly cement-based composite material of dredged material comprises 100-120 parts of dredged silt material, 20-40 parts of composite cementitious material and 0.1-3 parts of superabsorbent resin. The composite cementitious material comprises magnesium phosphate cement, fly ash and oil tea fruit shell ash in a mass ratio of (3-6):(2-4):(0.2-2). The superabsorbent resin is a polymerization crosslinking product of water-soluble ene acid monomers containing imidazole groups and phosphoric acid groups, ene amide sulfonic acid monomers, ene alkyl siloxane monomers and post-crosslinking agents. The environmental-friendly cement-based composite material of dredged material is prepared by using dredged material as a main raw material to preliminarily separate by-product coarse aggregate, and combining a double solidification strategy of superabsorbent resin and cementitious material. The mechanical strength of the cement-based composite material is increased, and the leaching risk of heavy metals and chlorine ions is effectively reduced. An effective solution is found for harmless and resource utilization of dredged material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste utilization, and particularly relates to a dredged material environment-friendly cement-based composite material and a preparation method thereof. BACKGROUND

[0002] With the increasing efforts in water resource development, channel dredging, and water environment construction along rivers and coasts, the annual dredging amount in China has exceeded 1 billion cubic meters, making China the largest country in terms of annual dredged material production. The large amount of dredged material produced by dredging projects has become an urgent environmental problem. Generally, dredged material contains sand, stone, clay, organic humus, microbial residues, etc. Among them, sand and stone have high recycling value, especially in the construction field. However, the clay part is plastic and easy to accumulate pollutants, and there are many challenges in its recycling process, especially the problems of heavy metal leaching and chloride ion leaching. If it is used to manufacture concrete and road base materials, the heavy metals (such as Cr, Cu, Pb, Zn, etc.) and chloride ions in it may leach out under certain conditions, which has a negative impact on the environment and the durability of the building structure. For example, the leaching of chloride ions can accelerate the corrosion of steel bars in concrete, reducing the service life of the structure. In addition, the leaching of heavy metals can lead to soil and water pollution, posing a threat to the ecosystem and human health.

[0003] In view of the current situation of the difficulty of high-value utilization of dredged material, solidification, as a common method for treating dredged sediment, aims to reduce the leaching or migration risk of heavy metals and chloride ions in dredged material, thereby improving the safety factor of its application in the construction field. However, most existing solidifying agents are mainly based on cement and slag, and their solidification effectiveness and chemical stability are limited. Moreover, they are not effective in treating dredged sediment with high water content, which hinders the full exploitation of the environmental benefits and economic value of dredged material. Therefore, the actual application scenarios have higher requirements for the solidification process of dredged material, the compatibility between the solidifying agent and the dredged material, and the solidification stability. SUMMARY

[0004] Based on the above problems, the present application provides a dredged material environment-friendly cement-based composite material and a preparation method thereof.

[0005] In one aspect, the present application provides a dredged material environment-friendly cement-based composite material, which comprises, by weight, 100-120 parts of dredged sediment material, 20-40 parts of composite cementitious material, and 0.1-3 parts of superabsorbent resin; the composite cementitious material comprises magnesium phosphate cement, fly ash, and oil tea fruit shell ash in a mass ratio of (3-6):(2-4):(0.2-2).

[0006] The superabsorbent resin is a polymerization cross-linked product of a water-soluble ene acid monomer containing an imidazole group and a phosphate group, an ene amide sulfonic acid monomer, an ene siloxane monomer, and a post-cross-linking agent.

[0007] As preferred, the water-soluble enoic acid monomer containing imidazole group and phosphate group is synthesized by amine imidazole synthesis reaction of pyridoxal phosphate, (2E)-3-(6-amino-3-pyridyl) acrylic acid and tert-butyl isocyanide under catalysis of ZrCl4; the reaction schematic diagram is as follows:

[0008] The molar ratio of (2E)-3-(6-amino-3-pyridyl)-2-propenoic acid, tert-butyl isocyanide, pyridoxal phosphate and ZrCl4 is 1:1:1:(0.1~0.12), and the reaction condition is stirring at 60~80℃ oil bath under nitrogen atmosphere, in the presence of anhydrous organic solvent and external agent for 6~10h.

[0009] As preferred, the external agent includes antioxidant vitamin C, desiccant anhydrous magnesium sulfate and polymerization inhibitor p-methyl phenol, and the amount is 0.1~0.5wt%, 5~10wt% and 0.1~0.3wt% of the total mass of the reactants, respectively.

[0010] The above reaction is a multi-component reaction, and the mechanism is that aldehyde and amino first form imine, and then imine is ring-closed with isocyanide to obtain amino imidazole. The addition of three external agents in the reaction system can reduce the generation of by-products and improve the reaction yield. Among them, vitamin C as an antioxidant can inhibit the self oxidation-reduction reaction of pyridoxal phosphate; the addition of anhydrous magnesium sulfate desiccant avoids the hydrolysis reaction of tert-butyl isocyanide; the addition of polymerization inhibitor p-methyl phenol avoids the polymerization reaction of (2E)-3-(6-amino-3-pyridyl) acrylic acid. Preferably, pyridoxal phosphate, (2E)-3-(6-amino-3-pyridyl) acrylic acid and tert-butyl isocyanide monomers are pretreated by drying before reaction.

[0011] As preferred, the molar ratio of the water-soluble enoic acid monomer containing imidazole group and phosphate group, the enoic amide sulfonic acid monomer and the enoic siloxane monomer is (1~2):(3~5):(2~3), the post-crosslinking agent is bis(methacryloyloxyethyl) hydrogen phosphate, and the amount is 0.1~0.4mol% of the total molar amount of the water-soluble enoic acid monomer containing imidazole group and phosphate group, the enoic amide sulfonic acid monomer and the enoic siloxane monomer.

[0012] As preferred, the enoic amide sulfonic acid monomer includes enoic amide sulfonic acid and its salts, and the enoic amide sulfonic acid and its salts are selected from one of 2-acrylamido-2-methylpropanesulfonic acid, 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonic acid sodium salt and 3-[(3-methylacrylamidopropyl)dimethylammonio]propane-1-sulfonic acid salt; the enoic siloxane is selected from one of vinyltrimethoxysilane, allyltriethoxysilane, vinyl diethoxymethyl silane and triacetoxy vinyl silane.

[0013] The high water absorbent resin provided by the application has sulfonic acid group, phosphoric acid, hydroxyl group, amino group and amide, etc., which can quickly form hydrogen bond with water molecules, promote the absorption of water molecules, and the water absorption rate is much higher than that of common sodium polyacrylate high water absorbent resin. Meanwhile, the imidazole group, phosphoric acid group and heavy metal ions have good coordination ability, which can fix the heavy metals in the form of stable complex and phosphate precipitation, and prevent the leaching thereof; the sulfonic acid group can significantly reduce the migration of chloride ions by forming non-water-soluble minerals; the sulfonic acid group and pyridine ring also have good strength and stability in mechanical properties; and the siloxane chain can enhance the mechanical strength of the resin network, so that the dredged material environment-friendly cement-based composite material has better chemical stability and solidification stability.

[0014] Preferably, the oil tea fruit shell ash is obtained by grinding the waste oil tea fruit shell into powder, and then sieving through an 80-mesh sieve, and has a specific surface area of 400 m 2 / kg or more. 2 / kg, and a 28d activity index of 70% or more.

[0015] Preferably, the dredged material environment-friendly cement-based composite material further comprises borax, and the amount of borax is 0.3wt%-1.5wt% of the mass of the magnesium phosphate cement.

[0016] In another aspect, the application provides a preparation process of the above-mentioned dredged material environment-friendly cement-based composite material, comprising the following steps:

[0017] S1, the dredged material is sequentially subjected to magnetic separation, dehydration and grading screening, to separate out a dredged silt and sand material with a particle size of less than 5 mm and a water content of 65%-80%, and a 5-20 mm continuous particle size graded stone coarse aggregate; the grading screening refers to sequentially using screens with a pore size of 20 mm, 10 mm and 5 mm for screening;

[0018] S2, the high water absorbent resin and the dredged silt and sand material are mixed in proportion, and stirred for 1 min to form a semi-cured dredged material; meanwhile, the fly ash, the magnesium phosphate cement, the mineral powder and the borax are dry-mixed in another stirrer for 2-3 min to obtain a mixed cementitious material;

[0019] S3, the semi-cured dredged material and the mixed cementitious material are mixed, and stirred for 2-4 min to obtain a cement-based composite material slurry, which is subjected to molding, shaping and curing operations to obtain the dredged material environment-friendly cement-based composite material.

[0020] The application has the following beneficial effects:

[0021] The present application provides a new technical route for the treatment of dredged material solid waste, which is characterized in that the dredged material is used as the main raw material, the by-product coarse aggregate is preliminarily separated, and the dredged material environment-friendly cement-based composite material is prepared by combining the double solidification strategies of superabsorbent resin and cementitious material, so that the leaching risk of heavy metal ions and chloride ions is effectively reduced, and the mechanical properties of the cement-based composite material are enhanced.

[0022] The present application finds an effective solution for the harmless and resource utilization of dredged material, effectively alleviates the environmental problems caused by the disordered piling of waste dredged material, and effectively improves the high-value utilization level of agricultural and forestry residues by integrating the recycling of oil tea fruit shells, thereby improving the overall efficiency and benefit of resource utilization. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The nuclear magnetic resonance spectrum of the water-soluble enoic acid monomer containing an imidazole group and a phosphoric acid group. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0025] The sources of raw materials or equipment manufacturers are as follows:

[0026] The dredged material of Xiangjiang Changsha to Chenglingji first-class channel of Xiangjiang Changsha comprehensive hub three-line ship lock project in Hunan was used, and the soil performance is shown in Table 1:

[0027] Table 1

[0028]

[0029] U-shaped magnesium phosphate cement, 100-200 mesh, compressive strength 58 MPa (28d), flexural strength 7 MPa (28d), Guizhou Phos-Materials Co., Ltd.;

[0030] P·O 52.5 ordinary portland cement, the execution standard is GB175-2007, China Resources Cement Holdings Limited; the main technical indexes are shown in Table 2.

[0031] Table 2

[0032]

[0033] Grade I fly ash, Guodian Sheneng Huayunshan Power Co., Ltd.; the characteristic indexes are shown in Table 3.

[0034] Table 3

[0035]

[0036] The oil tea fruit shell was crushed, dried at 70°C to constant weight, calcined at 600°C for 2h, and sieved through a 60 mesh screen to obtain oil tea fruit shell ash with a specific surface area of 408m 2 / kg, and its chemical composition is shown in Table 4.

[0037] Table 4 (unit: wt. %)

[0038]

[0039] As shown in Table 4, the ash of the calcined oil tea fruit shell is mainly composed of silicates, aluminum oxide, iron oxide and other inorganic minerals; during the calcination process, part of the organic matter cannot be completely decomposed, so the carbon content in the ash is relatively high; the ash also contains trace elements such as potassium, magnesium, sulfur and phosphorus.

[0040] The acrylic high water absorbent resin provided by Funaxin New Material Technology (Shanghai) Co., Ltd. has main parameters shown in Table 5.

[0041] Table 5

[0042]

[0043] TX7A250 electromagnetic slurry de-ironing machine, processing capacity 10~20t / h, magnetic field strength 3T, coil power 3kW, Shanghai Taixiong Magnetic Industry Co., Ltd.; RYBS-1000 square swing screen separator, processing capacity 8~15t / h, Henan Ruifite Machinery Equipment Co., Ltd.; XYSD-1000 high-pressure belt type deep sludge dewatering machine, raw sludge (water content 80%) processing capacity 0.8~1.5t / h, Yixing Xuyang Environmental Protection Technology Co., Ltd.; AVANCE superconducting nuclear magnetic resonance spectrometer, Germany Bruker Company.

[0044] In some embodiments of the present application, the water-soluble enic acid monomer is synthesized by the following steps: 0.01 mol of dry tert-butyl isocyanide, 0.01 mol of (2E)-3-(6-amino-3-pyridyl) acrylic acid and 0.01 mol of pyridoxal phosphate are added to 30 mL of anhydrous dioxane, then 0.47 g of ZrCl4, 21 mg of vitamin C, 0.52 g of anhydrous magnesium sulfate and 14 mg of p-methylphenol are added, the reaction system is deoxygenated with nitrogen for 20 min, then the stirring reaction is continued under nitrogen atmosphere, oil bath heating to 70°C for 7.5 h. After the reaction is completed, the system is cooled to room temperature, and ZrCl4, anhydrous magnesium sulfate and other insoluble substances are removed by filtration; the filtrate is purified by silica gel column chromatography (dioxane-methanol, volume ratio 8:1) to obtain a water-soluble enic acid monomer (Mw=476.4g / mol) with a yield of 72.8%.

[0045] The results of the nuclear magnetic resonance hydrogen spectrum of the water-soluble alkenoic acid monomer (Oxford NMR-I 400-600MHz nuclear magnetic resonance spectrometer, 400MHz, CDCl3) are shown in Table 1. Figure 1 .

[0046] .

[0047] Preparation Example 1

[0048] Synthesis of the superabsorbent resin: under an ice water bath, 0.048 mol of sodium hydroxide was added into 200 mL of a water-soluble alkenoic acid solution containing 0.06 mol of water-soluble alkenoic acid and stirred for 5 min; after the solution was returned to room temperature, 0.09 mol of 3-[(3-methacrylamidopropyl)dimethylammonio]propane-1-sulfonate was added; then 28 mL of a solution containing 0.06 mol of triacetoxyvinylsilane in ethanol, 2 mL of a solution containing 0.84 mmol of bis(methacryloxyethyl) hydrogen phosphate in ethanol was added and stirred uniformly to obtain a mixed solution with a total monomer concentration of 30 wt%, and nitrogen was introduced to remove oxygen for 20 min; 1 wt% of potassium persulfate was injected by a syringe, and the reaction was stirred at 60°C for 6 h to obtain a gel block; after washing with anhydrous ethanol, the gel block was cut into small pieces, placed in a vacuum dryer at 80°C until the weight was constant, crushed through an 80-mesh sieve; and the granular product was obtained and stored after drying.

[0049] Preparation Examples 2-3 were operated in the same manner as Preparation Example 1, except that the molar ratio of the three monomers was different, as shown in Table 6.

[0050] Performance test of the superabsorbent resin:

[0051] Water absorption ratio and centrifugal water retention capacity: 0.2 g of the superabsorbent resin was uniformly placed in a tea bag (60 mm x 85 mm) and heat-sealed; the tea bag containing the sample and a blank tea bag were placed in a plastic container containing 1000 mL of physiological saline, and immersed at 25°C for 30 min. The bag was taken out, hung to drip water for 10 min, and then weighed to obtain the weight W1 and W2, and the water absorption ratio (g / g) = (W1-W2) / 0.2. The tea bag containing the sample and the blank tea bag after the above test were centrifuged at a centrifugal force of 250G for 3 min, and weighed, respectively, and recorded as W3 and W4, respectively. The centrifugal water retention capacity (g / g) = (W3-W4) / 0.2.

[0052] Water absorption speed: the water absorption speed (s) was tested by the standard test method-weighing method in GB / T 23446-2009 Determination of water absorption rate of superabsorbent resin.

[0053] The raw material ratio of Preparation Examples 1-3 and the test results of the obtained superabsorbent resin are shown in Table 6.

[0054] Table 6

[0055]

[0056] Note: The molar ratio refers to n (water-soluble alkenoic acid) : n (alkenyl amide sulfonic acid) : n (alkenyl siloxane).

[0057] Example 1

[0058] Example 1 provides an environmentally friendly cement-based composite material of dredged material, the preparation steps are as follows:

[0059] S1, using the dredged material of Xiangjiang Changsha to Chenglingji first-class channel of Xiangjiang Changsha comprehensive hub three-line ship lock project, the ferromagnetic material is separated by a magnetic separator, and then dehydrated to a water content of 76% by a dehydrator; then sieved by a square swing screen (3 layers of screen mesh, screen mesh size is 20 mm, 10 mm and 5 mm in turn; screen surface inclination is 8°), to get 5~20 mm continuous graded stone coarse aggregate and particle size <5 mm dredged sand material. The main chemical components of the dredged sand material are determined by X-ray fluorescence spectrometer, see Table 7.

[0060] Table 7 (unit: wt. %)

[0061]

[0062] S2, take 1 kg of pretreated dredged sand material and 15 g of superabsorbent resin in a blender, stir for 1 min to form a semi-cured dredged material; at the same time, 96 g of fly ash, 192 g of magnesium phosphate cement, 32 g of oil tea fruit shell ash, 1.9 g of borax are dry mixed in another blender for 2~3 min to get mixed cementitious material;

[0063] S3, mix the semi-cured dredged material with the mixed cementitious material, stir at 500 rpm for 2~4 min to get cement-based composite material slurry, then mold, and cure at a curing temperature of (25±2)℃ and a humidity of (95±2)%, to get an environmentally friendly cement-based composite material of dredged material.

[0064] Examples 2-3

[0065] The difference from Example 1 is that the amount of superabsorbent resin is 5g and 25g respectively.

[0066] Examples 4-5

[0067] The difference from Example 1 is that the superabsorbent resin raw materials obtained from Preparation Examples 2 and 3 are used respectively.

[0068] Example 6

[0069] The difference from Example 1 is that the amount of mixed cementitious material added is 200 g, including 60 g of fly ash, 120 g of magnesium phosphate cement, and 20 g of oil tea fruit shell ash.

[0070] Comparative Example 1

[0071] The difference from Example 1 is that the superabsorbent resin is a commercially available acrylic superabsorbent resin, and the amount used is consistent with Example 1.

[0072] Comparative Example 2

[0073] The difference from Example 1 is that the magnesium phosphate cement is replaced with an equal amount of P·O 52.5 ordinary Portland cement.

[0074] Comparative Examples 3-4

[0075] The difference from Example 1 is that the amount of superabsorbent resin used is 1 g and 40 g.

[0076] The mechanical properties and chloride ion solidification rates of the dredged material environment-friendly cement-based composites obtained in Examples 1-6 and Comparative Examples 1-4 are tested. The unconfined compressive strength is referred to GB / T 50123-2019 “Standard for Soil Test Methods”, the chloride ion content is referred to JGJ-T322-2013 “Technical Specification for Detection of Chloride Ion Content in Concrete”, and the chloride ion solidification rate = chloride ion content of dredged material environment-friendly cement-based composite / chloride ion content of dredged silt.

[0077] The heavy metal leaching experiment of the dredged material environment-friendly cement-based composite is determined by referring to HJ557-2010 “Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method”, and the heavy metal content of the pretreated dredged silt is also determined. Agilent 7500ce ICP-MS inductively coupled plasma atomic emission spectrometer (detection limit of Cu is 4×10 -5 mg / L, Zn is 2×10 -5 mg / L, Cd is 5×10 -5 mg / L) is used for analysis by internal standard method. After the completion of the heavy metal acid leaching experiment, the compressive strength of the cement-based composite sample is retested, and compared with the initial 28d compressive strength to obtain the 28d unconfined compressive strength ratio.

[0078] The mechanical properties, chloride ion solidification rate, and 28d unconfined compressive strength ratio after acid leaching of the dredged material environment-friendly cement-based composite of each example and comparative example are shown in Table 8, and the heavy metal concentration of the dredged material environment-friendly cement-based composite and the screened dredged silt material is shown in Table 9.

[0079] Table 8

[0080]

[0081] From Table 8, the water absorption ratio of the commercially available acrylic superabsorbent resin used in Comparative Example 1 is far less than that of the superabsorbent resin provided by the present application, which directly leads to the insufficient curing efficiency; in addition, the results of the unconfined compressive strength ratio of the cement-based composite material further highlight the advantages of the siloxane groups and sulfonic acid groups contained in the superabsorbent resin provided by the present application in improving the durability and curing stability of the dredged material environment-friendly cement-based composite material. The decrease in the 28d unconfined compressive strength in Comparative Example 2 is attributed to the negative influence of heavy metal components in the dredged material on the hydration process of ordinary Portland cement.

[0082] Table 9

[0083]

[0084] Note: The standard limit value is derived from GB 5085.3-2007 "Hazardous Waste Identification Standard - Leaching Toxicity Identification".

[0085] From Table 9, the initial channel dredged material contains more heavy metal components, which are derived from pollution sources such as lead-containing paint, engine wear, galvanized equipment corrosion, and industrial wastewater discharged by electroplating and chemical industries, etc. The heavy metal ion concentration of the dredged material environment-friendly cement-based composite material prepared by the preparation strategy of the present application is lower than the standard limit value of GB 5085.3-2007 "Hazardous Waste Identification Standard - Leaching Toxicity Identification", which meets the environmental protection requirements.

[0086] The commercially available acrylic superabsorbent resin in Comparative Example 1 performs poorly in controlling heavy metal leaching due to the absence of functional groups. The ordinary Portland cement selected in Comparative Example 2 instead of magnesium phosphate cement is insufficient in metal curing capacity to make all heavy metal ion leaching concentrations fail to meet the standard limit value requirements.

[0087] From the test results of Table 6, Table 8 to Table 9, from Examples 1-3 and Comparative Examples 3-4, the superabsorbent resin exhibits the dual advantages of enhancing the strength of the cement-based composite material and effectively inhibiting the leaching of heavy metals and chloride ions within the limited dosage range of the present application. The superabsorbent resin mainly functions through the physical water absorption mechanism, i.e., even a small amount of addition will absorb a large amount of free water in the dredged material to form bound water, which in turn fills the soil particle interstices in the form of a gel state, reinforcing the strength of the cement-based composite material. In Comparative Example 3, the insufficient dosage of the superabsorbent resin cannot effectively solidify the dredged material, resulting in insufficient strength; on the contrary, in Comparative Example 4, the excessive dosage of the superabsorbent resin will form a large amount of gel particles in the soil, which will interfere with the strength skeleton formed by the hydration of the magnesium phosphate cement, also leading to a decrease in strength. In addition, as known from Example 6, when the total amount of cementitious material decreases, the strength and curing stability of the cement-based composite material also decrease to a certain extent, therefore the dosage of the cementitious material should also be accurately controlled within the range of the limit value of the present application.

[0088] In addition, the test results of Example 1, Examples 4-5 show the influence of the ratio of the three monomers in the superabsorbent resin on the performance of the cement-based composite material. The superabsorbent resin used in Example 1 and Example 4 contains a high proportion of functional groups such as phosphoric acid, sulfonic acid and imidazole, so the water absorption ratio and the heavy metal and chloride ion solidification effect of the cement-based composite material are better; the proportion of triacetoxyvinylsilane in Example 5 is higher, and the water absorption ratio is slightly reduced, but the mechanical properties are equivalent.

[0089] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, which should be covered by the scope of the claims of the present application.

Claims

1. An environmentally friendly cement-based composite material for dredging materials, characterized in that, By weight, it comprises 100-120 parts dredged silt, 20-40 parts composite cementitious material, and 0.1-3 parts superabsorbent resin; the composite cementitious material comprises magnesium phosphate cement, fly ash, and camellia fruit shell ash in a mass ratio of (3-6):(2-4):(0.2-2); the composite cementitious material also includes borax, used in an amount of 0.3wt%-1.5wt% of the mass of magnesium phosphate cement. The superabsorbent resin is a polymer crosslinked with water-soluble olefinic acid monomers containing imidazole and phosphate groups, alkenyl amide sulfonic acid monomers, alkenyl siloxane monomers, and a post-crosslinking agent. The water-soluble olefinic acid monomers containing imidazole and phosphate groups are obtained by synthesizing aminoimidazolium from pyridoxal phosphate, (2E)-3-(6-amino-3-pyridyl)acrylic acid, and tert-butylisocyanate under ZrCl4 catalysis. A schematic diagram of the reaction is shown below. ； The molar ratio of (2E)-3-(6-amino-3-pyridyl)acrylic acid, tert-butylisocyanate, pyridoxal phosphate and ZrCl4 is 1:1:1:(0.1~0.12), and the reaction conditions are: stirring in an oil bath at 60℃~80℃ for 6~10h in the presence of nitrogen atmosphere, anhydrous organic solvent and additives.

2. The cement-based composite material as described in claim 1, characterized in that, The additives include the antioxidant vitamin C, the desiccant anhydrous magnesium sulfate, and the polymerization inhibitor p-methylphenol, with the amounts used being 0.1%~0.5%, 5%~10%, and 0.1%~0.3% of the total mass of the reactants, respectively.

3. The cement-based composite material as described in claim 1, characterized in that, The molar ratio of the water-soluble olefin monomer containing imidazole and phosphate groups, the alkenyl amide sulfonic acid monomer, and the alkenyl siloxane monomer is (1~2):(3~5):(2~3), and the crosslinking agent is di(methacryloyloxyethyl) phosphate, which is used in an amount of 0.1~0.4 mol of the total molar amount of the water-soluble olefin monomer containing imidazole and phosphate groups, the alkenyl amide sulfonic acid monomer, and the alkenyl siloxane monomer.

4. The cement-based composite material as described in claim 1, characterized in that, The alkenylamide sulfonic acid monomers include alkenylamide sulfonic acids and their salts, wherein the alkenylamide sulfonic acids and their salts are selected from one of 2-acrylamido-2-methylpropanesulfonic acid, sodium 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonate, and 3-[(3-methacryloylaminopropyl)dimethylammonium]propane-1-sulfonate; and the alkenylsiloxane is selected from one of vinyltrimethoxysilane, allyltriethoxysilane, vinyldiethoxymethylsilane, and triacetoxyvinylsilane.

5. The cement-based composite material as described in claim 1, characterized in that, The camellia fruit shell ash is obtained by grinding, calcining, and sieving waste camellia fruit shells, and has a specific surface area ≥400 m². 2 / kg; the fly ash is Grade I or Grade II fly ash with a specific surface area ≥350m². 2 / kg, with a 28-day activity index ≥70%.

6. The preparation process of the environmentally friendly cement-based composite material for dredging materials as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. The dredged material is subjected to magnetic separation, dewatering and grading screening in sequence to separate dredged mud and sand with a particle size of <5mm and a moisture content of 65%~80% and coarse aggregate of stone with a continuous particle size distribution of 5~20mm; the grading screening refers to screening with screens with apertures of 20mm, 10mm and 5mm in sequence. S2. Mix the superabsorbent resin with the dredged mud and sand in a certain proportion and stir for 1 minute to form a semi-cured dredged material; at the same time, dry mix the fly ash, magnesium phosphate cement, camellia fruit shell ash, and borax in another mixer for 2-3 minutes to obtain a mixed cementitious material. S3. Mix the semi-cured dredging material with the mixed cementitious material and stir for 2-4 minutes to obtain a cement-based composite material slurry. Then, perform molding, curing, and other operations to obtain the environmentally friendly cement-based composite material of the dredging material.

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