Fiber-reinforced steel slag alkali slag concrete and preparation method thereof

Abstract

The invention discloses a fiber-reinforced steel slag alkali slag concrete and a preparation method thereof, belonging to the technical field of concrete preparation. The invention is used to solve the technical problem in the prior art that the flexural resistance and corrosion resistance of concrete need to be further improved. The concrete comprises the following raw materials in parts by weight: 35-36 parts of steel slag, 4-6 parts of alkali slag, 3-4 parts of mixed fibers, 2-3 parts of fly ash, 4-5 parts of 4M sodium hydroxide aqueous solution, 100-120 parts of coarse aggregate, 60-70 parts of fine aggregate and 21-26 parts of auxiliary additives. In the invention, siloxane segments on modified polyvinyl alcohol fibers are hydrolyzed to generate active sites, an inorganic magnesium salt is introduced on the surface of the modified polyvinyl alcohol fibers to prepare composite polyvinyl alcohol fibers, and modified basalt fibers activated by alkali solution are sized to obtain composite basalt fibers. The two fibers are mixed to obtain mixed fibers, and the concrete is structurally modified to finally prepare high-performance concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete preparation, and in particular to a fiber-reinforced steel slag alkali slag concrete and a preparation method thereof. Background Art

[0002] The development of fiber-reinforced steel slag and alkali slag concrete began with the demand for sustainable building materials, aiming to use industrial by-products such as steel slag and alkali slag to replace traditional cement and reduce carbon emissions. Early research focused on alkali activation technology, which activated steel slag and alkali slag through sodium water glass and sodium hydroxide to form a high-strength, low-permeability cementitious material. At the end of the 20th century, steel fibers were introduced to improve the tensile and crack resistance of concrete. Studies have shown that fiber reinforcement can significantly improve flexural strength and splitting tensile strength. In recent years, the application of modified fibers and nano-sizing technology has further optimized interfacial adhesion and durability, and wear resistance, compressive resistance and corrosion resistance have been improved. Currently, research is exploring the synergistic effect of waste and hybrid fiber systems to promote green and large-scale applications. In the future, standardized production and long-term performance evaluation will be the focus of development.

[0003] For example, Chinese patent CN114620973B discloses a method for preparing fiber concrete, which includes the following steps: treating plant fibers with a strong acid, then treating them with a strong alkali, shearing, and drying to obtain pretreated fibers; weighing the pretreated fibers and immersing them in a water-retaining agent, stirring for 1-1.5 hours; then adding an antioxidant, mixing them evenly, heating, and stirring to obtain modified plant fibers; weighing recycled aggregate, a water-reducing agent, an inorganic filler, a defoaming agent, cement, water, a corrosion inhibitor, and a surfactant; mixing them evenly with the modified plant fibers; stirring for 40-80 minutes to obtain a fiber concrete slurry; pouring the fiber concrete slurry into a mold to fix and shape it to obtain fiber concrete, which has good anti-cracking effect.

[0004] However, the above patent content is to obtain fiber concrete after acid treatment of plant fibers, mixing them with materials, and curing them. However, the plant fibers are only treated with acid and alkali to increase the surface roughness and activity, and no high-hardness inorganic coating or nanostructure modification is introduced. The interfacial adhesion between the fibers and the matrix is ​​weak, and the stress transfer efficiency is low, resulting in insufficient wear resistance and chemical stability of the fiber surface, easy to produce microcracks and damage, and difficult to effectively bridge cracks or dissipate energy. Therefore, the mechanical properties and durability of the prepared modified plant fibers are low, and the tensile and toughening effects are limited, which makes it difficult to meet the high requirements of high-performance concrete for crack resistance, wear resistance and durability. Summary of the Invention

[0005] The object of the present invention is to provide a fiber-reinforced steel slag alkali slag concrete and a preparation method thereof, so as to solve the technical problem in the prior art that the flexural and corrosion resistance of concrete need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solution: a fiber-reinforced steel slag alkali slag concrete, comprising the following raw materials in parts by weight: 35-36 parts of steel slag, 4-6 parts of alkali slag, 3-4 parts of mixed fibers, 2-3 parts of fly ash, 4-5 parts of 4M sodium hydroxide aqueous solution, 100-120 parts of coarse aggregate, 60-70 parts of fine aggregate and 21-26 parts of auxiliary additives;

[0007] The hybrid fiber is obtained by mixing composite polyvinyl alcohol fiber and composite basalt fiber in a ratio of 1g:1.0-1.2g;

[0008] The preparation method of the composite polyvinyl alcohol fiber comprises the following steps: mixing magnesium sulfate and deionized water, adding modified polyvinyl alcohol fiber to the reaction system, adjusting the pH of the reaction system to 8-10 using saturated sodium hydroxide, stirring at room temperature for 40-60 minutes, and post-treating to obtain the composite polyvinyl alcohol fiber.

[0009] The principle of preparing composite polyvinyl alcohol is as follows: under alkaline conditions, siloxy groups hydrolyze to form active silanol groups, while magnesium ions react with hydroxide ions to form magnesium hydroxide. The silanol groups serve as active sites and react with magnesium ions in the solution through electrostatic attraction and chemical bonding, inducing the in-situ deposition of magnesium hydroxide ions on the fiber surface to form an inorganic magnesium salt coating layer to obtain composite polyvinyl alcohol fibers.

[0010] Furthermore, the auxiliary additives include the following raw material compositions in parts by weight: 10-12 parts of sodium silicate, 10-12 parts of deionized water and 1-2 parts of polycarboxylic acid water reducer; further, in the process of preparing the composite polyvinyl alcohol fiber, the amount ratio of magnesium sulfate, deionized water and modified polyvinyl alcohol fiber is 2-3g:50-60mL:20-24g, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, the filter cake is washed 3-5 times with anhydrous ethanol and deionized water, and the filter cake is transferred to a reactor at a temperature of 60-80°C, and vacuum dried to constant weight to obtain the prepared composite polyvinyl alcohol fiber.

[0011] Furthermore, the preparation method of the modified polyvinyl alcohol fiber comprises the following steps:

[0012] A1. After mixing vinyl alcohol, vinyl triethoxysilane and N,N-dimethylformamide, the temperature of the reaction system is raised to 60-80° C., azobisisobutyronitrile is continuously added to the reaction system, and the reaction is kept warm for 2-4 hours, followed by post-treatment to obtain modified polyvinyl alcohol;

[0013] The reaction equation for preparing modified polyvinyl alcohol is:

[0014]

[0015] The principle of preparing modified polyvinyl alcohol is as follows: azobisisobutyronitrile decomposes under heating to generate free radicals. These free radicals trigger the cleavage of the vinyl double bonds of vinyl alcohol and vinyltriethoxysilane to form active monomer free radicals. The free radical monomers of vinyl alcohol and vinyltriethoxysilane are continuously polymerized through addition reactions to form graft copolymer chains to obtain modified polyvinyl alcohol.

[0016] A2. The modified polyvinyl alcohol and deionized water are mixed and stirred, the temperature of the reaction system is raised to 85-90° C., and the mixture is stirred until the modified polyvinyl alcohol is completely dissolved to obtain a spinning solution, and the spinning solution is spun to obtain modified polyvinyl alcohol fibers.

[0017] Furthermore, in step A1, the ratio of vinyl alcohol, vinyltriethoxysilane, N,N-dimethylformamide and azobisisobutyronitrile is 5-6g:2-3g:40-50mL:0.3-0.5g, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, the reaction solution is transferred to a rotary evaporator, the temperature of the rotary evaporator is increased to 60-80°C, and the modified polyvinyl alcohol is obtained by distillation under reduced pressure until no liquid is extracted;

[0018] Furthermore, in step A2, the amount ratio of modified polyvinyl alcohol and deionized water is 15-20g:100g, and the spinning operation is as follows: after filtering and degassing, the spinning solution is passed through a spinneret with a pore size of 0.20-0.24mm, extruded into a sodium sulfate aqueous solution with a temperature of 40-50°C and a concentration of 300-350g / L to coagulate to form nascent fibers, and the nascent fibers are subjected to a primary wet stretching with a stretching ratio of 1.5-2.5 times and a temperature of 50-60°C and a secondary dry stretching with a stretching ratio of 2-4 times and a temperature of 180-200°C, and then heat-set at 190-220°C for 10-30s, and then washed with deionized water at 30-40°C, dried at 80-100°C, and wound, and cut to obtain modified polyvinyl alcohol fibers with a length of 12-15mm.

[0019] Furthermore, the preparation method of the composite basalt fiber includes the following steps:

[0020] B1. After mixing and stirring basalt fiber and 3-5 wt% sodium hydroxide aqueous solution, the temperature of the reaction system is raised to 40-60° C., and the mixture is stirred at this temperature for 40-60 minutes, and then post-treated to obtain modified basalt fiber;

[0021] B2. Mixing and stirring the modified sizing agent and deionized water to obtain an impregnation liquid, placing the impregnation liquid into an impregnation tank, and impregnating the modified basalt fiber to obtain a composite basalt fiber.

[0022] The principle of preparing composite basalt fiber is as follows: under alkaline conditions, the surface of basalt fiber is activated to form active sites, obtaining modified basalt fiber. Its active sites combine with active groups such as hydroxyl groups in the modified sizing agent, allowing the modified sizing agent to adhere stably, thereby modifying the fiber surface and finally preparing composite basalt fiber.

[0023] Furthermore, in step B1, the ratio of the amount of the basalt fiber to the 3-5wt% sodium hydroxide aqueous solution is 1-2g:10-12mL, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, the filter cake is washed 3-5 times with anhydrous ethanol and deionized water, and the filter cake is transferred to a reactor at a temperature of 60-80°C, and vacuum dried to constant weight to obtain modified basalt fiber; further, in step B2, the modified sizing The dosage ratio of the agent and deionized water is 1-2g:20-30mL. The impregnation treatment includes: passing the modified basalt fiber through the impregnation tank at a speed of 3-5m / min, soaking for 20-30s, pressing the roller at a pressure of 0.1-0.2MPa, then drying it under hot air at 80-120℃ for 2-3min, and curing it in a vacuum drying oven at a temperature of 120-150℃ for 30-60s. Finally, the composite basalt fiber with a length of 12-18mm is obtained after winding and cutting.

[0024] Furthermore, the preparation method of the modified sizing agent comprises the following steps:

[0025] C1. After mixing and stirring ethylenediamine and N,N-dimethylformamide, the pH of the reaction system is adjusted to 8-10 using a saturated sodium hydroxide aqueous solution, and the temperature of the reaction system is raised to 40-60° C., 1,2,5,6-diepoxyethane is added to the reaction system, and the reaction is kept warm for 1-2 hours, and post-processed to obtain an ammoniated resin;

[0026] The reaction equation for preparing ammoniated resin is:

[0027]

[0028] The principle of preparing aminated resin is as follows: under alkaline conditions, the amino group of ethylenediamine acts as a nucleophile to attack the epoxy group of 1,2,5,6-diepoxyhexane. After the epoxy group is attacked, the ring is opened to generate hydroxyl groups and new CN bonds, forming a polyamine structure. The reaction continues to gradually form a long-chain aminated resin containing multiple hydroxyl groups and amino groups.

[0029] C2. Under the protection of nitrogen, after mixing and stirring the ammoniated resin and ethyl orthosilicate, anhydrous acetic acid and deionized water are added to the reactor, and the reaction system is heated to 70-90°C, stirred at this temperature for 3-4 hours, and then the temperature of the reaction system is lowered to room temperature, and stirring is continued for 4-5 hours. The modified sizing agent is obtained by post-treatment.

[0030] The principle of preparing the modified sizing agent is as follows: ethyl orthosilicate undergoes a hydrolysis reaction under acidic conditions to generate silanol bonds, which form an anionic-cationic charge interaction between the surface of the nano-silica inorganic core and the amino-modified epoxy resin organic shell, and a nano-inorganic-organic core-shell structure cationic sizing agent is synthesized in situ.

[0031] Furthermore, in step C1, the ratio of ethylenediamine, N,N-dimethylformamide and 1,2,5,6-diepoxyethane is 3-4 g:40-50 mL:5-6 g, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, the reaction solution is transferred to a rotary evaporator, the temperature of the rotary evaporator is increased to 60-80° C., and the mixture is distilled under reduced pressure until no liquid is extracted to obtain an ammoniated resin;

[0032] Furthermore, in step C2, the usage ratio of the ammoniated resin, ethyl orthosilicate, anhydrous acetic acid and deionized water is 10-12 g: 2-3 g: 1-2 g: 40-50 mL, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, the reaction liquid is transferred to a rotary evaporator, the temperature of the rotary evaporator is increased to 60-80 ° C, and the modified sizing agent is obtained after distillation under reduced pressure until no liquid is extracted.

[0033] The present invention also discloses a method for preparing fiber-reinforced steel slag alkali slag concrete, comprising the following steps:

[0034] S1. Mixed fibers, fine aggregate, fly ash, steel slag, and alkali slag are placed in a stirring kettle and mixed evenly. Coarse aggregate is added and stirred for 3-5 minutes. Then, a 4M aqueous sodium hydroxide solution and auxiliary additives are added and stirred for 5-8 minutes to obtain a concrete body.

[0035] S2. Transfer the concrete body into a mold, transfer the mold to a vibration table, vibrate for 1-2 minutes, use a scraper to flatten the surface ridges and cover the surface of the material with plastic wrap, then transfer the mold to a standard curing box with a temperature of 25°C and a humidity of 95%. After curing at constant temperature and humidity for 24-36 hours, demold the mold, soak in room temperature water for 20-24 hours, and dry to obtain composite concrete.

[0036] The present invention has the following beneficial effects:

[0037] 1. The present invention utilizes the hydrolysis of siloxane segments in modified polyvinyl alcohol fibers to generate active sites for incorporating inorganic magnesium salts to form a composite structure, which can enhance surface roughness and chemical bonding with the cement matrix, thereby improving interfacial adhesion, achieving effective stress transfer, inhibiting the expansion of microcracks, and improving compressive strength. The hard magnesium salt layer also enhances fiber wear resistance and reduces surface wear; the composite basalt fiber is activated by alkali treatment and coated with a cationic nano-inorganic-organic core-shell impregnant to form a dense interface layer, which significantly improves wear resistance and matrix bonding, thereby optimizing stress distribution. In the hybrid fiber system, the high toughness of the composite polyvinyl alcohol fiber provides crack bridging and energy dissipation, while the high modulus of the composite basalt fiber provides rigid support, which together inhibit crack expansion and stress concentration, thereby improving compressive strength. The reinforced interface network of the hybrid fiber with the matrix minimizes porosity and wear, significantly improving the wear resistance and compressive properties of concrete.

[0038] 2. The present invention also modifies the polyvinyl alcohol fiber by hydrolyzing the siloxane chain segments to anchor the magnesium salt, exhibiting enhanced surface texture and chemical reactivity, promoting strong adhesion to the cement matrix, helping to effectively transfer stress, reduce the generation of cracks, and improve bending and tensile capacity. The inherent ductility of the polyvinyl alcohol fiber absorbs energy during deformation and significantly enhances its resistance to bending and tensile cracking. The composite basalt fiber is alkali-activated and coated with a nano-inorganic-organic core-shell cationic impregnant to form a tightly bonded interface layer, strengthening matrix anchoring and improving stress distribution. The high stiffness of the composite basalt fiber can offset the expansion of cracks under tensile and bending loads. In the hybrid fiber system, the composite polyvinyl alcohol fiber can reduce the early microcrack propagation, while the composite basalt fiber provides structural stiffness to resist larger crack openings, synergistically amplifying the bending strength. This reinforced fiber-matrix network effectively disperses tensile stress and prevents splitting failure, thereby significantly improving the bending and splitting tensile strength of concrete.

[0039] 3. The present invention also forms a chemically stable composite structure by hydrolyzing the siloxane segments in the modified polyvinyl alcohol fibers and combining them with magnesium salts. The magnesium salt layer enhances the surface durability of the fibers and reduces their sensitivity to chemical attack, thereby providing a strong interfacial bond with the cement matrix and minimizing the corrosion pathways of corrosive agents. Similarly, composite basalt fibers activated by alkali treatment and coated with a nano-inorganic-organic core-shell cationic impregnant form a dense protective surface layer to prevent chemical corrosion. This treatment strengthens the fiber-matrix interface, forming a compact barrier that prevents the ingress of moisture and corrosive ions. In the hybrid fiber system, the composite polyvinyl alcohol fibers ensure an elastic and flexible network that maintains structural integrity under chemical stress, while the inherent chemical inertness and stiffness of the basalt fibers further enhance the matrix's resistance to degradation. This tightly bonded fiber-matrix system effectively seals micropores and cracks, significantly improving the corrosion resistance of concrete. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] The coarse aggregate used in the present invention is 4.5 mm building crushed stone;

[0042] The fine aggregate used in the present invention is natural river sand obtained by passing through a 50-mesh sieve;

[0043] The steel slag and alkali slag used in the present invention are waste materials generated in industrial production;

[0044] The basalt fiber used in the present invention is selected from Jiangsu Jumao New Material Technology Co., Ltd.

[0045] The fly ash used in the present invention is selected from Wuhan Jiyesheng Chemical Co., Ltd., with the product number A01085;

[0046] The polycarboxylate water-reducing agent used in the present invention is selected from Guangdong Wengjiang Chemical Reagent Co., Ltd., and the product number is PA96208. Example 1

[0047] This embodiment provides a method for preparing fiber-reinforced composite polyvinyl alcohol fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0048] Step ①, preparation of modified polyvinyl alcohol

[0049] Weigh: 50.0g vinyl alcohol, 20.0g vinyl triethoxysilane and 400.0mL N,N-dimethylformamide are added to the reactor and stirred. The temperature of the reactor is raised to 60°C. 3.0g azobisisobutyronitrile is continued to be added to the reactor. The reaction is kept warm for 2 hours. After the reaction is completed, the temperature of the reactor is lowered to room temperature. The reaction liquid is transferred to a rotary evaporator. The temperature of the rotary evaporator is raised to 60°C. After vacuum distillation until no liquid is extracted, modified polyvinyl alcohol is obtained. Step ②, preparation of modified polyvinyl alcohol fiber

[0050] Weighing: 45.0 g of modified polyvinyl alcohol and 300.0 g of deionized water were added to a reactor and stirred. The temperature of the reactor was raised to 85° C. and stirred until the modified polyvinyl alcohol was completely dissolved to obtain a spinning solution.

[0051] The spinning solution was filtered and degassed, passed through a spinneret with a pore size of 0.20 mm, and extruded into a sodium sulfate aqueous solution with a temperature of 40°C and a concentration of 300 g / L to coagulate into nascent fibers. The nascent fibers were subjected to a primary wet stretching with a stretching ratio of 1.5 times and a temperature of 50°C and a secondary dry stretching with a stretching ratio of 2 times and a temperature of 180°C, and then heat-set at 160°C for 10 seconds. The fibers were then washed with deionized water at 30°C, dried at 80°C, and wound up, and cut to obtain modified polyvinyl alcohol fibers with a length of 12.0 mm.

[0052] Step ③, preparation of composite polyvinyl alcohol fiber

[0053] Weigh: 2.0 g of magnesium sulfate and 50.0 mL of deionized water were added to the reactor and stirred. After adding 20.0 g of modified polyvinyl alcohol fiber to the reactor, saturated sodium hydroxide was used to adjust the pH of the reaction system to 8 and stirred at room temperature for 40 minutes. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 3 times with anhydrous ethanol and deionized water. The filter cake was transferred to a reactor at a temperature of 60°C and vacuum dried to constant weight to obtain the prepared composite polyvinyl alcohol fiber.

[0054] Example 2

[0055] This embodiment provides a method for preparing fiber-reinforced composite polyvinyl alcohol fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0056] Step ①, preparation of modified polyvinyl alcohol

[0057] Weigh: 60.0g of vinyl alcohol, 30.0g of vinyltriethoxysilane and 500.0mL of N,N-dimethylformamide were added to the reactor and stirred. The temperature of the reactor was raised to 80°C, and 5.0g of azobisisobutyronitrile was continued to be added to the reactor. The reaction was kept warm for 4h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 80°C, and the reaction was carried out by vacuum distillation until no liquid was extracted to obtain modified polyvinyl alcohol.

[0058] Step 2: Preparation of modified polyvinyl alcohol fiber

[0059] Weighing: 60.0 g of modified polyvinyl alcohol and 300.0 g of deionized water were added to a reactor and stirred. The temperature of the reactor was raised to 90° C. and stirred until the modified polyvinyl alcohol was completely dissolved to obtain a spinning solution.

[0060] The spinning solution was filtered and degassed, passed through a spinneret with a pore size of 0.24 mm, and extruded into a sodium sulfate aqueous solution with a temperature of 50°C and a concentration of 350 g / L to coagulate into nascent fibers. The nascent fibers were subjected to a primary wet stretching with a stretching ratio of 2.5 times and a temperature of 60°C and a secondary dry stretching with a stretching ratio of 4 times and a temperature of 200°C, and then heat-set at 220°C for 30 seconds. The fibers were then washed with deionized water at 40°C, dried at 100°C, and wound up, and cut to obtain modified polyvinyl alcohol fibers with a length of 15.0 mm.

[0061] Step 3: Preparation of composite polyvinyl alcohol fiber

[0062] Weigh: 3.0 g of magnesium sulfate and 60.0 mL of deionized water were added to the reactor and stirred. After adding 24.0 g of modified polyvinyl alcohol fiber to the reactor, saturated sodium hydroxide was used to adjust the pH of the reaction system to 10 and stirred at room temperature for 60 minutes. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 5 times with anhydrous ethanol and deionized water. The filter cake was transferred to a reactor at a temperature of 80°C and vacuum dried to constant weight to obtain the prepared composite polyvinyl alcohol fiber.

[0063] Example 3

[0064] This embodiment provides a method for preparing fiber-reinforced composite polyvinyl alcohol fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0065] Step ①, preparation of modified polyvinyl alcohol

[0066] Weigh: 54.0g of vinyl alcohol, 24.0g of vinyltriethoxysilane and 450.0mL of N,N-dimethylformamide were added to the reactor and stirred. The temperature of the reactor was raised to 70°C, and 4.0g of azobisisobutyronitrile was continued to be added to the reactor. The reaction was kept warm for 3 hours. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 70°C, and the modified polyvinyl alcohol was obtained after distillation under reduced pressure until no liquid was extracted.

[0067] Step ②, preparation of modified polyvinyl alcohol fiber

[0068] Weighing: 54.0 g of modified polyvinyl alcohol and 300.0 g of deionized water were added to a reactor and stirred. The temperature of the reactor was raised to 90° C. and stirred until the modified polyvinyl alcohol was completely dissolved to obtain a spinning solution.

[0069] The spinning solution was filtered and degassed, passed through a spinneret with a pore size of 0.21 mm, and extruded into a sodium sulfate aqueous solution with a temperature of 45°C and a concentration of 320.0 g / L to coagulate into nascent fibers. The nascent fibers were subjected to a primary wet stretching with a stretching ratio of 3.0 times and a temperature of 55°C and a secondary dry stretching with a stretching ratio of 3 times and a temperature of 200°C, and then heat-set at 220°C for 20 seconds. The fibers were then washed with deionized water at 30°C, dried at 90°C, and wound up, and cut to obtain modified polyvinyl alcohol fibers with a length of 12.0 mm.

[0070] Step ③, preparation of composite polyvinyl alcohol fiber

[0071] Weigh: 2.5 g of magnesium sulfate and 54.0 mL of deionized water were added to the reactor and stirred. After adding 21.0 g of modified polyvinyl alcohol fiber to the reactor, saturated sodium hydroxide was used to adjust the pH of the reaction system to 9 and stirred at room temperature for 50 minutes. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 4 times with anhydrous ethanol and deionized water. The filter cake was transferred to a reactor at a temperature of 70°C and vacuum dried to constant weight to obtain the prepared composite polyvinyl alcohol fiber.

[0072] Example 4

[0073] This embodiment provides a method for preparing fiber-reinforced composite basalt fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0074] Step I: Preparation of ammoniated resin

[0075] Weigh: 30.0g of ethylenediamine and 400.0mL of N,N-dimethylformamide were added to the reactor and stirred. After adjusting the pH of the reaction system to 8 with a saturated sodium hydroxide aqueous solution and raising the temperature of the reactor to 40°C, 50.0g of 1,2,5,6-diepoxyhexane was added to the reactor and kept warm for 1h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 60°C and distilled under reduced pressure until no liquid was produced to obtain an ammoniated resin.

[0076] Step II: Preparation of modified sizing agent

[0077] Under the protection of nitrogen, 60.0 g of ammoniated resin and 12.0 g of ethyl orthosilicate were weighed and added to a reactor and stirred. Then, 6.0 g of anhydrous acetic acid and 240.0 mL of deionized water were added to the reactor, and the reactor was heated to 70° C. and stirred for 3 hours. After the reactor temperature was lowered to room temperature, stirring was continued for 4 hours. After the reaction was completed, the reactor temperature was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 60° C. and distilled under reduced pressure until no liquid was extracted to obtain a modified sizing agent.

[0078] Step III: Preparation of modified basalt fiber

[0079] Weigh: 100.0 g of basalt fiber and 1000.0 mL of 3 wt% sodium hydroxide aqueous solution were added to a reactor and stirred. The temperature of the reactor was raised to 40°C and stirred for 40 minutes. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed three times with anhydrous ethanol and deionized water. The filter cake was transferred to a reactor at a temperature of 60°C and vacuum dried to constant weight to obtain modified basalt fiber.

[0080] Step IV: Preparation of composite basalt fiber

[0081] Weigh: 30.0g modified sizing agent and 600.0mL deionized water are added to the reactor and stirred to obtain an impregnation liquid. The impregnation liquid is placed in an impregnation tank, and the modified basalt fiber is passed through the impregnation tank at a speed of 3m / min, soaked for 20s, pressed with a roller at a pressure of 0.1MPa, and then dried under hot air at 80℃ for 2min. After that, it is cured in a vacuum drying oven at a temperature of 120℃ for 30s, and finally wound and cut to obtain a composite basalt fiber with a length of 12mm.

[0082] Example 5

[0083] This embodiment provides a method for preparing fiber-reinforced composite basalt fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0084] Step I: Preparation of ammoniated resin

[0085] Weigh: 40.0g of ethylenediamine and 500.0mL of N,N-dimethylformamide were added to the reactor and stirred. Saturated sodium hydroxide aqueous solution was used to adjust the pH of the reaction system to 10, and the temperature of the reactor was raised to 60°C. Then, 60.0g of 1,2,5,6-diepoxyhexane was added to the reactor and kept warm for 2h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 80°C, and the reaction was distilled under reduced pressure until no liquid was extracted to obtain an ammoniated resin.

[0086] Step II: Preparation of modified sizing agent

[0087] Under the protection of nitrogen, 72.0 g of ammoniated resin and 18.0 g of ethyl orthosilicate were weighed and added to a reactor and stirred. Then, 12.0 g of anhydrous acetic acid and 300.0 mL of deionized water were added to the reactor, and the reactor was heated to 90° C. and stirred for 4 hours. After the reactor temperature was lowered to room temperature, stirring was continued for 5 hours. After the reaction was completed, the reactor temperature was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 80° C. and distilled under reduced pressure until no liquid was extracted to obtain a modified sizing agent.

[0088] Step III: Preparation of modified basalt fiber

[0089] 200.0 g of basalt fiber and 1200.0 mL of 5 wt% sodium hydroxide aqueous solution were weighed and added to a reactor and stirred. The temperature of the reactor was raised to 60 ° C and stirred for 60 minutes. After the reaction was completed, the temperature of the reactor was lowered to room temperature, the reaction liquid was filtered to collect the filter cake, and the filter cake was washed 5 times with anhydrous ethanol and deionized water. The filter cake was transferred to a reactor at a temperature of 80 ° C and vacuum dried to constant weight to obtain modified basalt fiber.

[0090] Step IV: Preparation of composite basalt fiber

[0091] Weigh: 60.0g modified sizing agent and 900.0mL deionized water are added to the reactor and stirred to obtain an impregnation liquid. The impregnation liquid is placed in an impregnation tank, and the modified basalt fiber is passed through the impregnation tank at a speed of 5m / min, soaked for 30s, pressed with a roller at a pressure of 0.2MPa, and then dried under hot air at 120℃ for 3min. After that, it is cured in a vacuum drying oven at a temperature of 150℃ for 60s, and finally wound and cut to obtain a composite basalt fiber with a length of 18mm.

[0092] Example 6

[0093] This embodiment provides a method for preparing fiber-reinforced composite basalt fiber for preparing steel slag alkali slag concrete, comprising the following steps:

[0094] Step I: Preparation of ammoniated resin

[0095] Weigh: 36.0g of ethylenediamine and 500.0mL of N,N-dimethylformamide were added to the reactor and stirred. Saturated sodium hydroxide aqueous solution was used to adjust the pH of the reaction system to 9, and the temperature of the reactor was raised to 50°C. Then, 54.0g of 1,2,5,6-diepoxyhexane was added to the reactor and kept warm for 2h. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and the reaction liquid was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 80°C, and the reaction was distilled under reduced pressure until no liquid was extracted to obtain an ammoniated resin.

[0096] Step II: Preparation of modified sizing agent

[0097] Under the protection of nitrogen, 70.0 g of ammoniated resin and 24.0 g of ethyl orthosilicate were weighed and added to a reactor and stirred. Then, 10.0 g of anhydrous acetic acid and 270.0 mL of deionized water were added to the reactor, and the reactor was heated to 80° C. and stirred for 3 h. After the reactor temperature was lowered to room temperature, stirring was continued for 5 h. After the reaction was completed, the reactor temperature was lowered to room temperature, and the reaction solution was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 70° C. and distilled under reduced pressure until no liquid was extracted to obtain a modified sizing agent.

[0098] Step III: Preparation of modified basalt fiber

[0099] Weigh: 160.0g basalt fiber and 1200.0mL 4wt% sodium hydroxide aqueous solution are added to the reactor and stirred. The reactor temperature is raised to 50°C and stirred for 50 minutes. After the reaction is completed, the reactor temperature is lowered to room temperature, the reaction liquid is filtered to collect the filter cake, and the filter cake is washed 4 times with anhydrous ethanol and deionized water. The filter cake is transferred to a reactor at a temperature of 70°C and vacuum dried to constant weight to obtain modified basalt fiber. Step IV: Preparation of composite basalt fiber

[0100] Weigh: 45.0g modified sizing agent and 720.0mL deionized water are added to the reactor and stirred to obtain an impregnation liquid. The impregnation liquid is placed in an impregnation tank, and the modified basalt fiber is passed through the impregnation tank at a speed of 4m / min, soaked for 24s, pressed with a roller at a pressure of 0.2MPa, and then dried under hot air at 100℃ for 3min. After that, it is cured in a vacuum drying oven at a temperature of 150℃ for 45s, and finally wound and cut to obtain a composite basalt fiber with a length of 15mm.

[0101] Example 7

[0102] This embodiment provides a method for preparing fiber-reinforced steel slag alkali slag concrete, comprising the following steps:

[0103] Step 1: Prepare concrete body

[0104] Weigh: 10.0 g of the composite polyvinyl alcohol fiber prepared in Example 1 and 10.0 g of the composite basalt fiber prepared in Example 4 and mix them to obtain a hybrid fiber;

[0105] Weigh out: 10 parts of sodium silicate, 10 parts of deionized water and 1 part of polycarboxylate water reducer and mix to obtain an auxiliary additive;

[0106] Weigh 3 parts of mixed fiber, 60 parts of fine aggregate, 2 parts of fly ash, 35 parts of steel slag and 4 parts of alkali slag into a stirring tank and mix them evenly. Then, add 100 parts of coarse aggregate and stir for 3 minutes. Then, add 4 parts of 4M sodium hydroxide aqueous solution and 21 parts of auxiliary additives and stir for 5 minutes to obtain a concrete body.

[0107] Step 2: Prepare composite concrete

[0108] The concrete body was transferred to the mold, and the mold was transferred to a vibration table. After vibrating for 1 minute, the surface ridges were flattened with a scraper and the surface of the material was covered with plastic wrap. The mold was then transferred to a standard curing box with a temperature of 25°C and a humidity of 95%. After constant temperature and humidity curing for 24 hours, the mold was demoulded, soaked in room temperature water for 20 hours, and dried to obtain composite concrete.

[0109] Example 8

[0110] This embodiment provides a method for preparing fiber-reinforced steel slag alkali slag concrete, comprising the following steps:

[0111] Step 1: Prepare concrete body

[0112] Weigh: 10.0 g of the composite polyvinyl alcohol fiber prepared in Example 2 and 12.0 g of the composite basalt fiber prepared in Example 5 and mix them to obtain a hybrid fiber;

[0113] Weigh: 12 parts of sodium silicate, 12 parts of deionized water and 2 parts of polycarboxylate water reducer and mix to obtain an auxiliary additive;

[0114] Weigh 4 parts of mixed fiber, 70 parts of fine aggregate, 3 parts of fly ash, 36 parts of steel slag and 6 parts of alkali slag into a stirring tank and mix them evenly. Then, add 120 parts of coarse aggregate and stir for 5 minutes. Then, add 5 parts of 4M sodium hydroxide aqueous solution and 26 parts of auxiliary additives and stir for 8 minutes to obtain a concrete body.

[0115] Step 2: Prepare composite concrete

[0116] The concrete body was transferred to the mold, and the mold was transferred to a vibration table. After vibrating for 2 minutes, the surface ridges were flattened with a scraper and the surface of the material was covered with plastic wrap. The mold was then transferred to a standard curing box with a temperature of 25°C and a humidity of 95%. After constant temperature and humidity curing for 36 hours, the mold was demoulded, soaked in room temperature water for 24 hours, and dried to obtain composite concrete.

[0117] Example 9

[0118] This embodiment provides a method for preparing fiber-reinforced steel slag alkali slag concrete, comprising the following steps:

[0119] Step 1: Prepare concrete body

[0120] Weigh: 10.0 g of the composite polyvinyl alcohol fiber prepared in Example 3 and 12.0 g of the composite basalt fiber prepared in Example 6 and mix them to obtain a hybrid fiber;

[0121] Weigh and mix 12 parts of sodium silicate, 12 parts of deionized water, and 1 part of polycarboxylate water reducer to obtain an auxiliary additive;

[0122] Weigh 6 parts of mixed fiber, 64 parts of fine aggregate, 3 parts of fly ash, 36 parts of steel slag and 5 parts of alkali slag into a stirring tank and mix them evenly. Then, add 120 parts of coarse aggregate and stir for 4 minutes. Then, add 5 parts of 4M sodium hydroxide aqueous solution and 24 parts of auxiliary additives and stir for 6 minutes to obtain a concrete body.

[0123] Step 2: Prepare composite concrete

[0124] The concrete body was transferred to the mold, and the mold was transferred to a vibration table. After vibrating for 2 minutes, the surface ridges were flattened with a scraper and the surface of the material was covered with plastic wrap. The mold was then transferred to a standard curing box with a temperature of 25°C and a humidity of 95%. After constant temperature and humidity curing for 30 hours, the mold was demoulded, soaked in room temperature water for 21 hours, and dried to obtain composite concrete.

[0125] Comparative Example 1

[0126] The difference between this comparative example and Example 9 is that, during the preparation process of the composite polyvinyl alcohol fiber used in this comparative example, step ③ is omitted.

[0127] Comparative Example 2

[0128] The difference between this comparative example and Example 9 is that, in the preparation process of the composite basalt fiber used in this comparative example, step II is omitted.

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 9 is that, during the preparation process of the composite basalt fiber used in this comparative example, step IV is omitted.

[0131] Performance testing:

[0132] The flexural strength, compressive strength, splitting tensile strength and wear resistance of the composite concrete prepared in Examples 7-9 and Comparative Examples 1-3 after 28 days of solidification were tested with reference to the standard GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete";

[0133] The sulfate erosion resistance of the composite concrete prepared in Examples 7-9 and Comparative Examples 1-3 after 28 days of solidification was tested with reference to the standard GB / T 50082-2024 "Standard for Test Methods for Long-term Performance and Durability of Concrete". Specific data are shown in Table 1.

[0134] Table 1 - Performance test data of each sample

[0135]

[0136] Data Analysis:

[0137] After comparing and analyzing the data in Table 1, it can be found that the composite concrete prepared by the present invention has a flexural strength of 14.84 MPa, a compressive strength of 66.88 MPa, a splitting tensile strength of 7.92 MPa, and an abrasion loss of 1.06 kg·m after 45 cycles. 2 At the same time, the sulfate resistance grade is KS150, and all data are better than the control example;

[0138] By comparing the data of Example 9 and Comparative Examples 1-3, it can be found that the wear resistance and compressive resistance of the composite concrete prepared in Comparative Examples 1-3 are significantly weaker than the composite concrete prepared in Example 9, indicating that the inorganic magnesium salt coating of the modified polyvinyl alcohol fiber and the nano-inorganic-organic core-shell sizing agent treatment of the modified basalt fiber jointly optimize the fiber surface hardness, interface adhesion and stress transfer efficiency, significantly improving the wear resistance and compressive resistance. However, Comparative Example 1 lacks magnesium salt coating, and the wear resistance and interface adhesion of the polyvinyl alcohol fiber are insufficient; Comparative Example 2 lacks inorganic particles, and the hardness and adhesion of the sizing agent are reduced; Comparative Example 3 is not sized, and the basalt fiber surface is smooth and the interface is weakened. All three lead to a decrease in the interface performance between the fiber and the matrix, weakened wear resistance, reduced crack inhibition ability, and insufficient compressive strength.

[0139] By comparing the data of Example 9 and Comparative Examples 1-3, it can be found that the flexural strength and splitting tensile strength of the composite concrete prepared in Comparative Examples 1-3 are significantly weaker than the composite concrete prepared in Example 9, indicating that the inorganic magnesium salt coating of the modified polyvinyl alcohol fiber and the nano-inorganic-organic core-shell sizing agent treatment of the modified basalt fiber significantly enhance the interfacial bonding between the fiber and the matrix, optimize the stress transfer and crack suppression capabilities, and the toughness and rigidity of the hybrid fiber synergistically improve the flexural strength and splitting tensile strength. However, Comparative Example 1 lacks magnesium salt coating, and the PVA fiber interfacial bonding and toughness enhancement are insufficient; Comparative Example 2 lacks inorganic particles, the sizing agent bonding force decreases, and the rigidity effect of the basalt fiber is limited; Comparative Example 3 is not sized, the basalt fiber interface is weakened, and the rigid support fails. All three weaken the crack control ability due to the decline in interface performance, making the flexural strength and splitting tensile strength significantly lower than the examples;

[0140] By comparing the data of Example 9 and Comparative Examples 1-3, it can be found that the corrosion resistance of the composite concrete prepared in Comparative Examples 1-3 is significantly weaker than that of the composite concrete prepared in Example 9, indicating that the inorganic magnesium salt coating of the modified polyvinyl alcohol fiber and the nano-inorganic-organic core-shell sizing agent treatment of the modified basalt fiber jointly enhance the chemical stability of the fiber and the interface density with the matrix, significantly improving the corrosion resistance. However, Comparative Example 1 lacks magnesium salt coating, and the chemical erosion resistance and interface protection of the polyvinyl alcohol fiber are insufficient; Comparative Example 2 lacks inorganic particles, and the chemical stability and interface density of the sizing agent are reduced; Comparative Example 3 is not sized, and the basalt fiber interface is loose and susceptible to corrosive ion penetration. All three are significantly less corrosive due to insufficient fiber surface protection and weakened interface, resulting in aggravated corrosive ion penetration, and the corrosion resistance is significantly lower than that of the examples.

[0141] By comparing the performance test data of Example 9 and Comparative Examples 1-3 as a whole, it is finally explained that the present invention obtains a polyvinyl alcohol segment with a siloxane structure embedded in a segment by a free radical polymerization reaction to obtain modified polyvinyl alcohol, and obtains modified polyvinyl alcohol fiber by wet spinning, and finally uses the hydrolysis of the siloxane segment to generate active sites, thereby introducing inorganic magnesium salt on the surface of the modified polyvinyl alcohol fiber to prepare a composite polyvinyl alcohol fiber; and obtains a long chain structure by ring-opening polymerization of diamine and epoxy groups, and uses tetraethyl orthosilicate to undergo a hydrolysis reaction under acidic conditions to hydrolyze and generate silanol bonds, so that an anionic-cationic charge interaction is formed between the surface of the nano-silica inorganic core and the amino-modified epoxy resin organic shell, and a nano-inorganic-organic core-shell structure cationic sizing agent is synthesized in situ, and the modified basalt fiber activated by alkali solution is sizing treated to obtain composite basalt fiber. The two fibers are mixed to obtain hybrid fiber, and the concrete is structurally modified to finally prepare a high-performance concrete.

[0142] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A fiber-reinforced steel slag alkali slag concrete, characterized in that: The raw material composition comprises the following parts by weight: 35-36 parts of steel slag, 4-6 parts of alkali slag, 3-4 parts of mixed fibers, 2-3 parts of fly ash, 4-5 parts of 4M sodium hydroxide aqueous solution, 100-120 parts of coarse aggregate, 60-70 parts of fine aggregate and 21-26 parts of auxiliary additives; The hybrid fiber is obtained by mixing composite polyvinyl alcohol fiber and composite basalt fiber in a ratio of 1g:1.0-1.2g; The preparation method of the composite polyvinyl alcohol fiber comprises: mixing magnesium sulfate and deionized water, adding modified polyvinyl alcohol fiber to the reaction system, adjusting the pH of the reaction system to 8-10 using saturated sodium hydroxide, stirring at room temperature for 40-60 minutes, and post-treating to obtain the composite polyvinyl alcohol fiber; The preparation method of the modified polyvinyl alcohol fiber comprises the following steps: A1. After mixing vinyl alcohol, vinyl triethoxysilane and N,N-dimethylformamide, the temperature of the reaction system is raised to 60-80° C., azobisisobutyronitrile is continuously added to the reaction system, and the reaction is kept warm for 2-4 hours, followed by post-treatment to obtain modified polyvinyl alcohol; A2. Mixing and stirring the modified polyvinyl alcohol and deionized water, raising the temperature of the reaction system to 85-90° C., stirring until the modified polyvinyl alcohol is completely dissolved, to obtain a spinning solution, and spinning the spinning solution to obtain modified polyvinyl alcohol fibers; The preparation method of the composite basalt fiber comprises the following steps: B1. After mixing and stirring basalt fiber and 3-5 wt% sodium hydroxide aqueous solution, the temperature of the reaction system is raised to 40-60° C., and the mixture is stirred at this temperature for 40-60 minutes, and then post-treated to obtain modified basalt fiber; B2. Mixing and stirring the modified sizing agent and deionized water to obtain an impregnation solution, placing the impregnation solution into an impregnation tank, and impregnating the modified basalt fiber to obtain a composite basalt fiber; The preparation method of the modified sizing agent comprises the following steps: C1. After mixing and stirring ethylenediamine and N,N-dimethylformamide, the pH of the reaction system is adjusted to 8-10 using a saturated sodium hydroxide aqueous solution, and the temperature of the reaction system is raised to 40-60° C., 1,2,5,6-diepoxyethane is added to the reaction system, and the reaction is kept warm for 1-2 hours, and post-processed to obtain an ammoniated resin; C2. Under the protection of nitrogen, after mixing and stirring the ammoniated resin and ethyl orthosilicate, anhydrous acetic acid and deionized water are added to the reactor, and the reaction system is heated to 70-90°C, stirred at this temperature for 3-4 hours, and then the temperature of the reaction system is lowered to room temperature, and stirring is continued for 4-5 hours. The modified sizing agent is obtained by post-treatment.

2. The fiber-reinforced steel slag alkali slag concrete according to claim 1, characterized in that: The auxiliary additives include the following raw materials in parts by weight: 10-12 parts of sodium silicate, 10-12 parts of deionized water and 1-2 parts of polycarboxylic acid water reducer; in the process of preparing the composite polyvinyl alcohol fiber, the usage ratio of magnesium sulfate, deionized water and modified polyvinyl alcohol fiber is 2-3g:50-60mL:20-24g.

3. The fiber-reinforced steel slag alkali slag concrete according to claim 1, characterized in that: In step A1, the usage ratio of the vinyl alcohol, vinyl triethoxysilane, N,N-dimethylformamide and azobisisobutyronitrile is 5-6 g:2-3 g:40-50 mL:0.3-0.5 g; in step A2, the usage ratio of the modified polyvinyl alcohol and deionized water is 15-20 g:100 g.

4. The fiber-reinforced steel slag alkali slag concrete according to claim 1, characterized in that: In step B1, the ratio of the basalt fiber to the 3-5 wt% sodium hydroxide aqueous solution is 1-2 g:10-12 mL; in step B2, the ratio of the modified sizing agent to deionized water is 1-2 g:20-30 mL.

5. The fiber-reinforced steel slag alkali slag concrete according to claim 1, characterized in that: In step C1, the usage ratio of ethylenediamine, N,N-dimethylformamide and 1,2,5,6-diepoxyhexane is 3-4 g:40-50 mL:5-6 g; in step C2, the usage ratio of amination resin, ethyl orthosilicate, anhydrous acetic acid and deionized water is 10-12 g:2-3 g:1-2 g:40-50 mL.

6. A method for preparing fiber-reinforced steel slag alkali slag concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Mixed fibers, fine aggregate, fly ash, steel slag, and alkali slag are placed in a stirring kettle and mixed evenly. Coarse aggregate is added and stirred for 3-5 minutes. Then, a 4M aqueous sodium hydroxide solution and auxiliary additives are added and stirred for 5-8 minutes to obtain a concrete body. S2. Transfer the concrete body into a mold, transfer the mold to a vibration table, vibrate for 1-2 minutes, use a scraper to flatten the surface ridges and cover the surface of the material with plastic wrap, then transfer the mold to a standard curing box with a temperature of 25°C and a humidity of 95%. After curing at constant temperature and humidity for 24-36 hours, demold the mold, soak in room temperature water for 20-24 hours, and dry to obtain composite concrete.

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