Reinforced cement-based cover plate and preparation method thereof

Abstract

The invention belongs to the technical field of cement-based building materials, and particularly relates to an enhanced cement-based cover plate and a preparation method thereof. According to the reinforced cement-based cover plate, the boric acid ester modified basalt fiber bars with good mechanical properties are added, and the acidified calcium sulfate whiskers and the sulfydryl modified fly ash are used together, so that the reinforced cement-based cover plate is prepared, the compressive strength and the tensile strength of the cover plate are remarkably improved, and meanwhile, the abrasion coefficient is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of cement-based building materials, and particularly relates to a reinforced cement-based cover plate and a preparation method thereof. Background Art

[0002] At present, high-speed railway projects are being vigorously built all over the country. Most of the sidewalk covers and cable trough covers in the projects are currently made of reinforced concrete or active powder concrete covers mixed with steel fibers. Although reinforced concrete covers have the advantages of high compressive strength, strong applicability, low price, and easy construction and production, they have low flexural and bending strength. Therefore, reinforced concrete covers have the disadvantages of high brittleness, low ultimate tensile strain, and weak impact resistance. At the same time, there are still many difficult problems in its application, such as steel fibers are prickly during railway maintenance, and steel fibers are easy to rust, which has an adverse effect on the track circuit.

[0003] A Chinese patent (publication number CN113896473B) discloses a carbon fiber reinforced cover plate for tunnels. The cover plate is made of a skeleton structure of overlapped carbon fiber reinforcements and cast by a matrix material. The matrix material consists of a mixed resin system, a multi-component curing agent compound system, and a filler system. The cover plate prepared by the invention has the advantages of high strength, good toughness, excellent corrosion resistance, and low deadweight. The production process adopts on-site prefabrication and installation on the construction site. It can be applied to cover plate projects in tunnels of highways, railways, municipal roads, etc., as well as other application fields with high requirements for performance and deadweight. It can effectively solve the problems of existing cover plates being damaged during transportation and seriously affecting durability after damage. However, the patent does not solve the problems of low compressive strength and tensile strength and large wear coefficient of cement-based cover plates in the prior art, which seriously affects their actual use.

[0004] Therefore, how to improve the compressive strength and tensile strength of cement-based cover plates by adding basalt fiber reinforcements with good mechanical properties in combination with other modified components, while effectively reducing the wear coefficient, has become a direction that needs to be focused on. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a reinforced cement-based cover plate and a preparation method thereof, aiming to solve the problems of low compressive strength and tensile strength, high wear coefficient, etc. of the cement-based cover plate in the prior art.

[0006] The present invention prepares a reinforced cement-based cover plate by adding borate-modified basalt fiber reinforcements with good mechanical properties, in combination with acidified calcium sulfate whiskers and mercapto-modified fly ash, which significantly improves the compressive strength and tensile strength of the cover plate and effectively reduces the wear coefficient.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows: A first aspect of the present invention provides a method for preparing a reinforced cement-based cover plate, comprising the following steps: Step S1: by weight, 4 to 6 parts of 2-aminoethyl diphenylborate are added to 140 to 160 parts of anhydrous ethanol, and stirred for 30 to 40 minutes to obtain an impregnation solution, 40 to 50 parts of basalt fiber reinforcement are added to the impregnation solution for 1 to 3 hours, and then dried at 106 to 110° C. for 2 to 4 hours to obtain borate-modified basalt fiber reinforcement; Step S2: by weight, 80-100 parts of cement, 100-120 parts of river sand, 60-70 parts of deionized water, 40-60 parts of crushed stone and 6-9 parts of water reducing agent are mixed uniformly to obtain cement slurry; Step S3: adding 10 to 20 parts of borate-modified basalt fiber reinforcement, 10 to 20 parts of calcium sulfate whiskers, 8 to 12 parts of modifier, 6 to 9 parts of retarder and 40 to 50 parts of fly ash to 280 to 300 parts of the cement slurry by weight, and stirring for 50 to 60 minutes to obtain concrete slurry; Step S4: pour the concrete slurry into a mold and vibrate it evenly, remove the mold after casting and forming, and obtain a reinforced cement-based cover plate.

[0008] By introducing borate functional groups on the surface of basalt fibers, the chemical compatibility and physical-mechanical bite between the fibers and the cement matrix can be improved. Borates can form an active coating on the fiber surface to promote the chemical bonding between the fibers and the cement paste, thereby enhancing the interfacial adhesion. Good interfacial adhesion promotes more effective stress transfer in the concrete matrix, reduces the expansion of cracks, and thereby improves the compressive strength of the overall structure.

[0009] As a preferred technical solution of the present invention, the calcium sulfate whisker is an acidified calcium sulfate whisker; the preparation method of the acidified calcium sulfate whisker comprises: adding 20 to 30 parts of calcium sulfate whisker to 200 to 240 parts of deionized water by weight and dispersing for 40 to 60 minutes, then adding 2 to 4 parts of trisodium phosphate and stirring for 2 to 4 hours, filtering, washing with deionized water, and drying to obtain an intermediate product; dispersing 20 to 30 parts of the intermediate product in 100 to 120 parts of anhydrous ethanol, then adding 6 to 10 parts of stearic acid for stirring reaction, filtering after the reaction is completed, washing with anhydrous ethanol, and vacuum drying to obtain the acidified calcium sulfate whisker.

[0010] As a preferred technical solution of the present invention, the diameter of the calcium sulfate whisker is 3-5 μm.

[0011] As a preferred technical solution of the present invention, the stirring reaction conditions include: a stirring speed of 100-200 r / min, a temperature of 60-70° C., and a time of 20-30 min.

[0012] Acidified calcium sulfate whiskers have a high aspect ratio and can form an effective stress transfer path in the cement matrix. When the material is subjected to tensile stress, the whiskers can act as a bridge during crack propagation, preventing or delaying further crack expansion and significantly improving the tensile strength of the cement-based cover plate.

[0013] As a preferred technical solution of the present invention, the fly ash is mercapto-modified fly ash; the preparation method of the mercapto-modified fly ash comprises: mixing 90 to 100 parts of anhydrous ethanol, 20 to 30 parts of deionized water and 6 to 8 parts of ammonia water by weight, stirring for 20 to 30 minutes at 32 to 36°C, then adding 20 to 24 parts of fly ash and 4 to 6 parts of (3-mercaptopropyl) triethoxysilane and stirring for 24 to 28 hours, centrifuging after the stirring to obtain a solid, washing the solid with anhydrous ethanol, and drying to obtain the mercapto-modified fly ash.

[0014] As a preferred technical solution of the present invention, the particle size of the fly ash is 40-50 μm.

[0015] Mercapto-modified fly ash can promote the growth of microcrystals during cement hydration, making the pores in the cement matrix smaller and more evenly distributed, which not only improves the density of the material, but also reduces the penetration path of moisture and harmful substances, thereby enhancing the wear resistance of the cement-based cover plate and reducing the wear coefficient.

[0016] As a preferred technical solution of the present invention, the modifier is 3-aminopropyltriethoxysilane and ethylene-vinyl acetate copolymer.

[0017] As a preferred technical solution of the present invention, the mass ratio of 3-aminopropyltriethoxysilane to ethylene-vinyl acetate copolymer in the modifier is (1~2):1.

[0018] By selecting a suitable mass ratio of 3-aminopropyltriethoxysilane and ethylene-vinyl acetate copolymer in the modifier, a good compounding effect of the two is ensured, thereby improving the compressive strength and tensile strength of the cement-based cover plate and reducing the wear coefficient.

[0019] As a preferred technical solution of the present invention, the retarder is selected from any one of sodium tripolyphosphate, citric acid, and sodium gluconate, or a combination of at least two of them.

[0020] The second aspect of the present invention provides a reinforced cement-based cover plate prepared by the method described in the first aspect.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The surface of the acidified calcium sulfate whisker of the present invention contains active groups such as carboxyl and hydroxyl, wherein the hydroxyl can combine with the borate of the borate-modified basalt fiber tendon, and the carboxyl can undergo a thioesterification reaction with the mercapto group in the modified fly ash. At the same time, the borate can also form a stable covalent bond with the mercapto group, thereby constructing a three-dimensional network structure. The three-dimensional network structure can form a bridging effect at the crack tip as a reinforcing phase, redistribute the stress on both sides of the crack, reduce the stress concentration at the crack tip, and improve the compressive strength and tensile strength of the material; at the same time, the network structure can effectively capture and fix abrasive particles, reduce the direct impact and scratches of abrasive particles on the material surface, thereby reducing the degree of abrasive wear and reducing the wear coefficient.

[0022] (2) The borate-modified basalt fiber reinforcement of the present invention can improve the chemical compatibility and physical mechanical bite between the fiber and the cement matrix by introducing borate functional groups on the surface of the basalt fiber. The borate can form an active coating on the fiber surface to promote the chemical bonding between the fiber and the cement paste, thereby enhancing the interfacial bonding. The good interfacial bonding promotes more effective stress transfer in the concrete matrix, reduces the expansion of cracks, and thus improves the compressive strength of the overall structure.

[0023] (3) The acidified calcium sulfate whiskers of the present invention have a high aspect ratio and can form an effective stress transfer path in the cement matrix. When the material is subjected to tensile stress, the whiskers can play a bridging role in the crack propagation process, thereby preventing or delaying the further propagation of the crack, reducing the impact of the crack, and significantly improving the tensile strength of the cement-based cover plate.

[0024] (4) The mercapto-modified fly ash of the present invention can promote the growth of microcrystals during cement hydration, making the pores in the cement matrix smaller and more evenly distributed, which not only improves the density of the material but also reduces the penetration path of moisture and harmful substances, thereby enhancing the wear resistance of the cement-based cover plate and reducing the wear coefficient. DETAILED DESCRIPTION

[0025] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0026] The sources of some components in the embodiments and comparative examples are as follows: Cement, product number CA-75, was purchased from Zhengzhou Kerui (Group) Refractory Materials Co., Ltd.; River sand, item number 5768, was purchased from Lingshou County Zehong Mineral Products Processing Plant; Crushed stone, item number LC01, purchased from Laizhou Baolailuo Stone Co., Ltd.; Basalt fiber reinforcement, item number GD-601, purchased from Shijiazhuang Yinhupo New Material Technology Co., Ltd.; Calcium sulfate whisker I, brand NP-M02-I30, diameter 5 μm, Jiangxi Fengzhu New Material Technology Co., Ltd.; Calcium sulfate whisker II, brand NP-S04-YE, diameter 25 μm, Jiangxi Fengzhu New Material Technology Co., Ltd.; 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, purchased from Sinopharm Chemical Reagent Co., Ltd.; Ethylene-vinyl acetate copolymer, product number P101482-1, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Water reducing agent, product number 008, purchased from Shandong Tianhong Chemical Co., Ltd.; Sodium tripolyphosphate, CAS No. 7758-29-4, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Citric acid, CAS No. 77-92-9, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Sodium gluconate, CAS No. 527-07-1, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Fly ash I, with a particle size of 44 μm, was purchased from Shijiazhuang Zed Mineral Products Co., Ltd.; Fly ash II, with a particle size of 80 μm, was purchased from Henan Borun Casting Materials Co., Ltd.; Fly ash III, with a particle size of 10 μm, was purchased from Hebei Baoting Engineering Construction Co., Ltd.; 2-Aminoethyl diphenylborate, CAS No. 524-95-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Trisodium phosphate, CAS No. 10101-89-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Stearic acid, CAS No. 57-11-4, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; Anhydrous ethanol, CAS No. 64-17-5, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Ammonia water, CAS No. 1336-21-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.; (3-Mercaptopropyl)triethoxysilane, CAS No. 14814-09-6, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0027] Preparation of acidified calcium sulfate whiskers: In parts by weight, 30 parts of calcium sulfate whiskers I (with a diameter of 5 μm) are added to 240 parts of deionized water and dispersed for 60 minutes, and then 4 parts of trisodium phosphate are added and stirred for 4 hours, filtered, washed with deionized water, and dried to obtain an intermediate product; 30 parts of the intermediate product are dispersed in 120 parts of anhydrous ethanol, and then 10 parts of stearic acid are added for stirring reaction (stirring speed is 200 r / min, temperature is 70°C, and time is 20 minutes). After the reaction is completed, it is filtered, washed with anhydrous ethanol, and vacuum dried to obtain acidified calcium sulfate whiskers.

[0028] Preparation of mercapto-modified fly ash: In parts by weight, 100 parts of anhydrous ethanol, 30 parts of deionized water and 8 parts of ammonia water are mixed, stirred at 36°C for 20 minutes, and then 24 parts of fly ash I (particle size of 44 μm) and 6 parts of (3-mercaptopropyl)triethoxysilane are added and stirred for 28 hours. After stirring, solid matter is obtained by centrifugation, and the solid matter is washed with anhydrous ethanol and dried to obtain mercapto-modified fly ash.

[0029] Embodiment 1: This embodiment provides a method for preparing a reinforced cement-based cover plate, comprising the following steps: Step S1: by weight, 6 parts of 2-aminoethyl diphenylborate are added to 160 parts of anhydrous ethanol, and stirred for 40 minutes to obtain an impregnation solution, 50 parts of basalt fiber reinforcement are added to the impregnation solution for 3 hours, and then dried at 110° C. for 2 hours to obtain borate-modified basalt fiber reinforcement; Step S2: by weight, 100 parts of cement, 120 parts of river sand, 70 parts of deionized water, 60 parts of crushed stone and 9 parts of water reducing agent are mixed evenly to obtain cement slurry; Step S3: adding 20 parts of borate-modified basalt fiber bars, 20 parts of acidified calcium sulfate whiskers, 12 parts of modifiers (8 parts of 3-aminopropyltriethoxysilane and 4 parts of ethylene-vinyl acetate copolymer), 9 parts of retarder sodium tripolyphosphate and 50 parts of mercapto-modified fly ash to 300 parts of the cement slurry, by weight, and stirring for 60 minutes to obtain concrete slurry; Step S4: pour the concrete slurry into a mold and vibrate it evenly, remove the mold after casting and forming, and obtain a reinforced cement-based cover plate.

[0030] Embodiment 2: This embodiment provides a method for preparing a reinforced cement-based cover plate, comprising the following steps: Step S1: by weight, 4 parts of 2-aminoethyl diphenylborate are added to 140 parts of anhydrous ethanol, and stirred for 30 minutes to obtain an impregnation solution, 40 parts of basalt fiber reinforcement are added to the impregnation solution for 1 hour, and then dried at 106° C. for 4 hours to obtain borate-modified basalt fiber reinforcement; Step S2: by weight, 80 parts of cement, 100 parts of river sand, 60 parts of deionized water, 40 parts of crushed stone and 6 parts of water reducing agent are mixed evenly to obtain cement slurry; Step S3: adding, by weight, 10 parts of borate-modified basalt fiber bars, 10 parts of acidified calcium sulfate whiskers, 8 parts of modifiers (4 parts of 3-aminopropyltriethoxysilane and 4 parts of ethylene-vinyl acetate copolymer), 6 parts of retarder citric acid and 40 parts of mercapto-modified fly ash to 280 parts of the cement slurry, and stirring for 50 minutes to obtain concrete slurry; Step S4: pour the concrete slurry into a mold and vibrate it evenly, remove the mold after casting and forming, and obtain a reinforced cement-based cover plate.

[0031] Embodiment 3, this embodiment provides a method for preparing a reinforced cement-based cover plate, comprising the following steps: Step S1: by weight, 5 parts of 2-aminoethyl diphenylborate are added to 150 parts of anhydrous ethanol, and stirred for 35 minutes to obtain an impregnation solution, 45 parts of basalt fiber reinforcement are added to the impregnation solution for 2 hours, and then dried at 108° C. for 3 hours to obtain borate-modified basalt fiber reinforcement; Step S2: by weight, 90 parts of cement, 110 parts of river sand, 65 parts of deionized water, 50 parts of crushed stone and 8 parts of water reducing agent are mixed evenly to obtain cement slurry; Step S3: adding, by weight, 15 parts of borate-modified basalt fiber bars, 15 parts of acidified calcium sulfate whiskers, 10 parts of modifiers (6 parts of 3-aminopropyltriethoxysilane and 4 parts of ethylene-vinyl acetate copolymer), 8 parts of retarder sodium gluconate and 45 parts of mercapto-modified fly ash to 290 parts of the cement slurry, and stirring for 55 minutes to obtain concrete slurry; Step S4: pour the concrete slurry into a mold and vibrate it evenly, remove the mold after casting and forming, and obtain a reinforced cement-based cover plate.

[0032] Comparative Example 1 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that commercially available basalt fiber reinforcements are used instead of borate-modified basalt fiber reinforcements.

[0033] Comparative Example 2 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that calcium sulfate whiskers I are used instead of acidified calcium sulfate whiskers.

[0034] Comparative Example 3 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that calcium sulfate whiskers II are used instead of calcium sulfate whiskers I to prepare acidified calcium sulfate whiskers.

[0035] Comparative Example 4 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that fly ash I is used to replace mercapto-modified fly ash.

[0036] Comparative Example 5 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that fly ash II is used instead of fly ash I to prepare mercapto-modified fly ash.

[0037] Comparative Example 6 This comparative example provides a method for preparing a cement-based cover plate, which differs from Example 1 in that fly ash III is used instead of fly ash I to prepare mercapto-modified fly ash.

[0038] The performance of the cement-based cover plates provided in the above embodiments and comparative examples was tested, and the testing method was as follows: (1) Compressive strength test: Test according to the requirements of GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete.

[0039] (2) Tensile strength test: Test according to the requirements of GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete.

[0040] (3) Abrasion resistance test: Test according to the requirements of GB / T 50081-2019 Standard for Test Methods for Physical and Mechanical Properties of Concrete.

[0041] The above performance test data is shown in Table 1: Table 1 Performance test results

[0042] From the above content, it can be seen that the present invention prepares a reinforced cement-based cover plate (Example 1 to Example 3) by adding borate-modified basalt fiber tendons with good mechanical properties, in combination with the use of acidified calcium sulfate whiskers and mercapto-modified fly ash. The compressive strength (28d) of the cover plate is 136.5~138.1MPa, the tensile strength (28d) is 8.3~8.7MPa, and the wear coefficient is 0.83~0.94.

[0043] Compared with Example 1, the use of commercially available basalt fiber tendons instead of borate-modified basalt fiber tendons reduces the compressive strength, reduces the tensile strength, and increases the wear coefficient (Comparative Example 1); Compared with Example 1, the use of calcium sulfate whisker I instead of acidified calcium sulfate whiskers reduces the compressive strength, reduces the tensile strength, and increases the wear coefficient (Comparative Example 2); Compared with Example 1, calcium sulfate whisker II is used to replace calcium sulfate whisker I for the preparation of acidified calcium sulfate whiskers. Since the diameter of calcium sulfate whisker II is too large, the modification effect is not good, so the compressive strength is reduced, the tensile strength is reduced, and the wear coefficient is increased (Comparative Example 3); Compared with Example 1, Compared with Example 1, when fly ash I was used to replace the mercapto-modified fly ash, the compressive strength decreased, the tensile strength decreased, and the wear coefficient increased (Comparative Example 4); compared with Example 1, when fly ash II was used to replace fly ash I for the preparation of mercapto-modified fly ash, the particle size of fly ash II was too large and the modification effect was not good, the compressive strength decreased, the tensile strength decreased, and the wear coefficient increased (Comparative Example 5); compared with Example 1, when fly ash III was used to replace fly ash I for the preparation of mercapto-modified fly ash, the particle size of fly ash III was too small and the modification effect was not good, the compressive strength decreased, the tensile strength decreased, and the wear coefficient increased (Comparative Example 6).

[0044] In summary, the present invention prepares a reinforced cement-based cover plate by adding borate-modified basalt fiber reinforcements with good mechanical properties, in combination with the use of acidified calcium sulfate whiskers and mercapto-modified fly ash, which significantly improves the compressive strength and tensile strength of the cover plate and effectively reduces the wear coefficient.

Claims

1. A method for preparing a reinforced cement-based cover plate, characterized in that: The following steps are involved: Step S1: by weight, 4 to 6 parts of 2-aminoethyl diphenylborate are added to 140 to 160 parts of anhydrous ethanol, and stirred for 30 to 40 minutes to obtain an impregnation solution, 40 to 50 parts of basalt fiber reinforcement are added to the impregnation solution for 1 to 3 hours, and then dried at 106 to 110° C. for 2 to 4 hours to obtain borate-modified basalt fiber reinforcement; Step S2: by weight, 80-100 parts of cement, 100-120 parts of river sand, 60-70 parts of deionized water, 40-60 parts of crushed stone and 6-9 parts of water reducing agent are mixed uniformly to obtain cement slurry; Step S3: adding 10 to 20 parts of borate-modified basalt fiber reinforcement, 10 to 20 parts of calcium sulfate whiskers, 8 to 12 parts of modifier, 6 to 9 parts of retarder and 40 to 50 parts of fly ash to 280 to 300 parts of the cement slurry by weight, and stirring for 50 to 60 minutes to obtain concrete slurry; Step S4: pouring the concrete slurry into a mold and vibrating it evenly, removing the mold after casting and forming, and obtaining a reinforced cement-based cover plate; The calcium sulfate whiskers are acidified calcium sulfate whiskers; The preparation method of the acidified calcium sulfate whisker comprises: adding 20 to 30 parts of calcium sulfate whisker to 200 to 240 parts of deionized water by weight and dispersing for 40 to 60 minutes, then adding 2 to 4 parts of trisodium phosphate and stirring for 2 to 4 hours, filtering, washing with deionized water, and drying to obtain an intermediate product; dispersing 20 to 30 parts of the intermediate product in 100 to 120 parts of anhydrous ethanol, then adding 6 to 10 parts of stearic acid for stirring reaction, filtering after the reaction is completed, washing with anhydrous ethanol, and vacuum drying to obtain the acidified calcium sulfate whisker; The diameter of the calcium sulfate whisker is 3-5 μm; The stirring reaction conditions include: stirring speed of 100-200 r / min, temperature of 60-70° C., and time of 20-30 min; The fly ash is mercapto-modified fly ash; The preparation method of the mercapto-modified fly ash comprises: mixing 90-100 parts of anhydrous ethanol, 20-30 parts of deionized water and 6-8 parts of ammonia water by weight, stirring for 20-30 minutes at 32-36° C., then adding 20-24 parts of fly ash and 4-6 parts of (3-mercaptopropyl) triethoxysilane and stirring for 24-28 hours, centrifuging to obtain a solid after the stirring is completed, washing the solid with anhydrous ethanol, and drying to obtain the mercapto-modified fly ash; The particle size of the fly ash is 40-50 μm.

2. The method for preparing a reinforced cement-based cover plate according to claim 1, characterized in that: The modifier is 3-aminopropyltriethoxysilane and ethylene-vinyl acetate copolymer.

3. The method for preparing a reinforced cement-based cover plate according to claim 2, characterized in that: The mass ratio of 3-aminopropyltriethoxysilane to ethylene-vinyl acetate copolymer in the modifier is (1-2):

1.

4. The method for preparing a reinforced cement-based cover plate according to claim 1, characterized in that: The retarder is selected from any one of sodium tripolyphosphate, citric acid, sodium gluconate, or a combination of at least two thereof.

5. A reinforced cement-based cover plate, characterized in that: Prepared according to the method according to any one of claims 1 to 4.

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