High-toughness and high-strength concrete and well lid and preparation method thereof

Abstract

The application discloses high-toughness and high-strength concrete and a well lid and a preparation method thereof, and belongs to the technical field of concrete well lids; the concrete comprises the following components in parts by weight: 100-120 parts of epoxy resin, 5-10 parts of anhydrous ethanol, 25-40 parts of T31 curing agent, 25-40 parts of modified carbon fiber-diatomic earth composite filler, 40-60 parts of fly ash, 5-10 parts of liquid butyl nitrile rubber, 400-450 parts of quartz fine sand and 5-15 parts of modified basalt fiber; the concrete contains the modified carbon fiber-diatomic earth composite filler and the modified basalt fiber; under the action of impact load, the two components jointly act, so that the material has high compressive strength when initially stressed, and can effectively dissipate energy when reaching the limit, resists sudden brittle failure, forms stronger energy absorption and impact resistance, and under the synergistic action, when facing various types and different development stages of stress failure, the stress failure can be effectively inhibited and the impact energy can be absorbed, so that the overall crack resistance and impact resistance of the concrete are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of concrete manhole cover technology, specifically, it relates to a high-toughness and high-strength concrete, a manhole cover, and a method for preparing the same. Background Technology

[0002] With the acceleration of urbanization, the pace of municipal construction is increasing rapidly, resulting in a dramatic increase in the number of municipal engineering facilities. In every corner of the city, we can find various underground pipeline inspection manhole covers, serving multiple sectors such as telecommunications, electricity, gas, heating, fire protection, and sanitation. These manhole covers are ubiquitous throughout the city's streets and alleys, becoming an indispensable part of urban infrastructure.

[0003] However, for a long time, cast iron manhole covers have been widely used in my country's municipal public utilities sector. While this material choice meets structural strength requirements to some extent, its inherent limitations, such as high processing energy consumption and environmental pollution, have significantly impacted project costs, environmental protection, and energy consumption. Especially now, the damage and illegal resale of manhole covers are commonplace, seriously affecting the normal operation of municipal facilities and posing a serious threat to citizens' traffic and personal safety, thus triggering a series of social problems and economic losses.

[0004] The prior art includes Chinese invention patent application number 202411694598.9, which discloses a high-strength concrete and manhole cover and its preparation method, comprising 475-485 parts by weight of cement, 715-725 parts by weight of coarse aggregate, 1075-1085 parts by weight of fine aggregate, 115-125 parts by weight of modified steel fiber, 9.2-9.8 parts by weight of polycarboxylate superplasticizer and 165-170 parts by weight of water.

[0005] The core matrix of existing technologies is cement. During the hydration process, cement will produce self-shrinkage and drying shrinkage, which will induce micro-stress inside the material. Even with fiber reinforcement, micro-defects or potential micro-cracks may form, becoming the starting point for the initiation and propagation of macro-cracks in the later stage. Therefore, cracking is still possible after long-term use.

[0006] Existing technologies mainly use steel fibers as reinforcement materials. Steel fibers are essentially metals, and they are still susceptible to corrosion in long-term service or in extremely humid or chlorine-rich environments. Once corrosion occurs, their volume expansion may cause internal stress, which in turn damages the concrete structure and renders the manhole cover ineffective. Furthermore, steel fibers have a high density and a large specific gravity, which may limit their application in certain scenarios where weight is a requirement.

[0007] Existing technology, such as Chinese invention patent application number 201811120457.0, discloses an epoxy resin-based composite manhole cover and its preparation method. This method uses epoxy resin as the matrix, and based on the stress characteristics of the manhole cover, prepares a bottom layer and a top layer, with basalt fiber mesh fabric added in between. While this structure can offer some resistance to overall bending on a macroscopic level, during the service life of the manhole cover, it is subjected to repeated impact loads, temperature changes, and moisture erosion. This easily leads to stress concentration at the interlayer interfaces, forming crack initiation points, ultimately causing structural delamination and failure, reducing the long-term reliability of the manhole cover. Furthermore, the PP fiber in the aforementioned prior art may not bond firmly to the matrix interface, easily slipping or pulling out under external force, failing to effectively bridge cracks and transfer stress.

[0008] Therefore, in order to solve the above-mentioned technical problems, this application provides a high-toughness and high-strength concrete and a manhole cover, and a method for preparing the same. Summary of the Invention

[0009] To address the deficiencies in the aforementioned technical solutions, the present invention aims to provide a high-toughness, high-strength concrete and a manhole cover, as well as a method for their preparation.

[0010] In one aspect, this application provides a technical solution for high-toughness and high-strength concrete: a high-toughness and high-strength concrete, the components of which include: 100-120 parts of epoxy resin, 5-10 parts of anhydrous ethanol, 25-40 parts of T31 curing agent, 25-40 parts of modified carbon fiber-diatomite composite filler, 40-60 parts of fly ash, 5-10 parts of liquid nitrile rubber, 400-450 parts of quartz fine sand; and 5-15 parts of modified basalt fiber.

[0011] The epoxy resin is bisphenol A type E44 epoxy resin;

[0012] The fineness modulus of the quartz sand is 2.4-2.7, and the particle size is 2-5 mm.

[0013] The fly ash is Class I ash with a specific surface area ≥350m². 2 / kg.

[0014] The preparation method of the modified carbon fiber-diatomite composite filler is as follows: Ethanol and deionized water are added to a reaction vessel and mixed evenly. KH-550 is then added and continuously stirred. Carbon fibers are then weighed and placed into the reaction vessel, ensuring that all carbon fibers are completely submerged in the solution. The container is then sealed and left to soak at room temperature for 8 hours. After soaking for 8 hours, excess solution is discarded, and the removed carbon fibers are evenly spread out and air-dried in a well-ventilated area for 1-2 hours to obtain KH-550 modified carbon fibers. The KH-550 modified carbon fibers are then placed in a mortar and diatomite is added. The mixture is gently and thoroughly stirred using a pestle. After stirring evenly, the mixture is spread out in a container and allowed to air-dry for 12 hours to obtain the modified carbon fiber-diatomite composite filler.

[0015] The carbon fiber is short-cut carbon fiber with an average diameter of 10 μm and a length of 1-2 cm;

[0016] The test performance indicators of the chopped carbon fiber are tensile strength greater than 4.8 GPa and modulus of 220 GPa.

[0017] Preparation method of modified basalt fiber: Deionized water and myristyltrimethylammonium bromide were added to a reaction vessel, the temperature was raised to 60°C, and the mixture was magnetically stirred for 30 min. Then the stirring was stopped, and pretreated basalt fiber was added to the reaction vessel, which was fully submerged and impregnated for 6 h. The mixture was then filtered and repeatedly rinsed with deionized water, and dried to constant weight to obtain an intermediate product. Anhydrous ethanol and deionized water were added to a reaction vessel, and then N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane was added. The temperature was raised to 60°C, and the mixture was magnetically stirred for 30 min. The intermediate product was then added to the reaction vessel, which was fully submerged and impregnated for 6 h. The mixture was then filtered and repeatedly rinsed with anhydrous ethanol. Finally, the final product was placed in an 80°C drying oven and dried for 12 h to obtain the self-made modified basalt fiber.

[0018] The pretreatment method of the basalt fiber is as follows: the basalt fiber is placed in a muffle furnace for heat treatment; after cooling in the furnace, it is placed in a hydrochloric acid solution with a concentration of 1 mol / L and heated to 80 degrees Celsius for acid washing for 5 hours; then filtered and the basalt fiber is repeatedly rinsed until the pH of the filtrate is 7. The basalt fiber is then collected and dried to constant weight to obtain the pretreated basalt fiber.

[0019] The heat treatment temperature of the muffle furnace is set to 500℃.

[0020] A method for preparing high-toughness and high-strength concrete is as follows: epoxy resin, anhydrous ethanol, modified carbon fiber-diatomite composite filler, fly ash, liquid nitrile rubber, quartz fine sand, and modified basalt fiber are added to a mixing container in sequence and stirred evenly for 2-3 minutes until completely mixed. Then, T31 curing agent is added and stirring is continued for 3-5 minutes until uniformly dispersed, thus preparing a high-toughness and high-strength concrete.

[0021] Secondly, the manhole cover provided in this application adopts the following technical solution:

[0022] A manhole cover includes a steel reinforcement skeleton and a concrete cover portion filled in the steel reinforcement skeleton, wherein the concrete cover portion is made of high-toughness and high-strength concrete as described in any one of the preceding claims.

[0023] Thirdly, the method for manufacturing a manhole cover provided in this application adopts the following technical solution:

[0024] A method for preparing a manhole cover, comprising the following steps: adding epoxy resin, anhydrous ethanol, modified carbon fiber-diatomite composite filler, fly ash, liquid nitrile rubber, and quartz fine sand in sequence to a mixing container and stirring evenly for 2-3 minutes until completely mixed; then adding T31 curing agent and stirring for another 3-5 minutes until evenly dispersed to obtain high-toughness and high-strength concrete; placing a reinforcing steel skeleton into a mold, then filling the reinforcing steel skeleton with high-toughness and high-strength concrete, vibrating evenly, curing for 28 hours, and then demolding to obtain the manhole cover.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The modified basalt fiber of this application, after modification with myristyltrimethylammonium bromide, exhibits steric hindrance due to its long carbon chain and electrostatic repulsion from the positively charged head groups. This prevents the basalt fiber from agglomerating during mixing with epoxy resin, resulting in more uniform fiber dispersion and improved load-bearing capacity. Furthermore, modification with N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane allows the methoxy groups to hydrolyze and generate active silanol groups, which can condense with the hydroxyl groups on the surface of the basalt fiber to form stable covalent bonds. This enables the stress to be effectively transferred to the high-strength basalt fiber when the concrete is under stress, allowing the fiber to fully exert its load-bearing capacity. It also prevents premature separation of the fiber from the matrix under external force, thus delaying material failure and improving the material's toughness and impact resistance. This characteristic makes it more suitable for manufacturing manhole covers that are frequently subjected to impacts.

[0027] 2. The modified carbon fiber-diatomaceous earth composite filler in this application utilizes carbon fiber, which possesses high strength and high modulus, to reinforce and bridge cracks in concrete. Treatment with KH-550 silane coupling agent significantly improves the interfacial compatibility and bond strength between the carbon fiber and the epoxy resin matrix, ensuring effective stress transfer from the matrix to the carbon fiber and fully leveraging its reinforcing potential. The KH-550-treated carbon fiber is mixed with diatomaceous earth, which has a porous structure and a large specific surface area. This facilitates further dispersion of the KH-550-modified carbon fiber in the epoxy matrix, reducing agglomeration and forming a more uniform reinforcing network. Furthermore, the porous structure and irregular morphology of the diatomaceous earth create a microscopic mechanical interlocking effect at the interface between the carbon fiber, diatomaceous earth, and epoxy matrix, further enhancing interfacial bonding. This allows the porous structure of the composite filler to absorb some energy through micro-fracture or deformation when subjected to impact, improving the material's toughness.

[0028] 3. The concrete of this application contains modified carbon fiber-diatomite composite filler and modified basalt fiber. Under impact load, the two components work together to give the material high compressive strength at the initial stress and to effectively dissipate energy and resist sudden brittle failure when the limit is reached, forming stronger energy absorption and impact resistance. Under the synergistic effect, it can effectively suppress and absorb impact energy when facing various types of stress failure at different stages of development, thereby significantly improving the overall crack resistance and impact resistance of the concrete and giving it excellent toughness. This allows the concrete material of this application to be used in the field of manhole covers for a longer service life. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Furthermore, regarding numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0031] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0032] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0033] In the following examples, "parts" refers to parts by weight.

[0034] Example 1

[0035] A high-toughness and high-strength concrete comprises, by weight: 100 parts epoxy resin, 5 parts anhydrous ethanol, 25 parts T31 curing agent, 25 parts modified carbon fiber-diatomite composite filler, 40 parts fly ash, 5 parts liquid nitrile rubber, 400 parts quartz fine sand, and 5 parts modified basalt fiber.

[0036] The epoxy resin is bisphenol A type E44 epoxy resin;

[0037] The fineness modulus of the quartz sand is 2.4-2.7, and the particle size is 2-5 mm.

[0038] The fly ash is Class I ash with a specific surface area ≥350m². 2 / kg.

[0039] The preparation method of the modified carbon fiber-diatomaceous earth composite filler is as follows: 18g of ethanol and 2g of deionized water are added to a reaction vessel and mixed evenly. Then, 5g of KH-550 silane coupling agent is slowly added while continuously stirring to ensure uniform dispersion of KH550. Next, 1g of carbon fiber is weighed and placed into the reaction vessel, ensuring all carbon fibers are completely submerged in the solution. The container is then sealed and left to soak at room temperature for 8 hours. After soaking for 8 hours, excess solution is discarded, and the removed carbon fibers are evenly spread to form a thin layer. The layer is then placed in a well-ventilated area to air dry for 1-2 hours to fully evaporate any adhering ethanol and excess moisture, thus obtaining the KH-550 modified carbon fiber. The KH-550 modified carbon fiber is then placed in a mortar, and 2g of diatomaceous earth is added. Using a pestle, the mixture is gently and thoroughly stirred to ensure that the diatomaceous earth particles are evenly adhered to and deposited on the surface of the carbon fiber. After thorough mixing, the mixture of modified carbon fiber and diatomaceous earth is spread out in a container and allowed to dry naturally for 12 hours. This yields the modified carbon fiber-diatomaceous earth composite filler.

[0040] The carbon fiber is short-cut carbon fiber with an average diameter of 10 μm and a length of 1-2 cm;

[0041] The test performance indicators of the chopped carbon fiber are tensile strength greater than 4.8 GPa and modulus of 220 GPa.

[0042] Pretreatment method of basalt fiber: Basalt fiber is placed in a muffle furnace for heat treatment at a temperature of 500℃ to remove impurities; after cooling in the furnace, it is placed in a 1mol / L hydrochloric acid solution and heated to 80℃ for acid washing for 5h; then filtered and the basalt fiber is repeatedly rinsed until the pH of the filtrate is 7. The basalt fiber is then collected and dried to constant weight to obtain the pretreated basalt fiber.

[0043] Preparation method of modified basalt fiber: Add 160 ml of deionized water and 1 g of myristyltrimethylammonium bromide to a reaction vessel, heat to 60 °C, and magnetically stir for 30 min; then stop stirring, add 10 g of pretreated basalt fiber to the reaction vessel, fully submerge, and impregnate for 6 h; then filter and repeatedly rinse with deionized water, and dry thoroughly to constant weight to obtain the intermediate product; add 135 ml of anhydrous ethanol and 15 ml of deionized water to the reaction vessel, then add 0.8 g of N-(β-aminoethyl)-γ -Aminopropylmethyldimethoxysilane was heated to 60 degrees Celsius and magnetically stirred for 30 minutes to fully hydrolyze N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane. Then, stirring was stopped, and 10 g of the intermediate product was added to the reaction vessel to fully submerge it and impregnate it for 6 hours. The mixture was then filtered and repeatedly washed with anhydrous ethanol to remove excess and unreacted N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane. Finally, the final product was dried in an 80-degree Celsius drying oven for 12 hours to obtain the self-made modified basalt fiber.

[0044] A method for preparing high-toughness and high-strength concrete is as follows: epoxy resin, anhydrous ethanol, modified carbon fiber-diatomite composite filler, fly ash, liquid nitrile rubber, quartz fine sand, and modified basalt fiber are added to a mixing container in sequence and stirred evenly for 2-3 minutes until completely mixed. Then, T31 curing agent is added and stirring is continued for 3-5 minutes until uniformly dispersed, thus preparing a high-toughness and high-strength concrete.

[0045] Example 2

[0046] A high-toughness and high-strength concrete comprises, by weight: 105 parts epoxy resin, 6 parts anhydrous ethanol, 28 parts T31 curing agent, 28 parts modified carbon fiber-diatomite composite filler, 32 parts fly ash, 6 parts liquid nitrile rubber, 410 parts quartz fine sand, and 8 parts modified basalt fiber.

[0047] In Example 2, the preparation methods of the modified carbon fiber-diatomite composite filler and the modified basalt fiber are the same as those in Example 1.

[0048] Example 3

[0049] A high-toughness and high-strength concrete comprises, by weight: 110 parts epoxy resin, 7 parts anhydrous ethanol, 32 parts T31 curing agent, 32 parts modified carbon fiber-diatomite composite filler, 50 parts fly ash, 7 parts liquid nitrile rubber, 430 parts quartz fine sand, and 10 parts modified basalt fiber.

[0050] In Example 3, the preparation methods of the modified carbon fiber-diatomite composite filler and the modified basalt fiber are the same as those in Example 1.

[0051] Example 4

[0052] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts modified carbon fiber-diatomite composite filler, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts modified basalt fiber.

[0053] In Example 4, the preparation methods of the modified carbon fiber-diatomite composite filler and the modified basalt fiber are the same as those in Example 1.

[0054] Example 5

[0055] A high-toughness and high-strength concrete comprises, by weight: 120 parts epoxy resin, 10 parts anhydrous ethanol, 40 parts T31 curing agent, 40 parts modified carbon fiber-diatomite composite filler, 60 parts fly ash, 10 parts liquid nitrile rubber, 450 parts quartz fine sand, and 15 parts modified basalt fiber.

[0056] In Example 5, the preparation methods of the modified carbon fiber-diatomite composite filler and the modified basalt fiber are the same as those in Example 1.

[0057] Comparative Example 1

[0058] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts diatomaceous earth, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts basalt fiber.

[0059] The difference between Comparative Example 1 and Example 4 is that the modification operation on diatomaceous earth and basalt fiber was omitted, and the commercially available products were directly applied to high-toughness and high-strength concrete.

[0060] Comparative Example 2

[0061] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts modified carbon fiber-diatomite composite filler, 55 parts fly ash, 8 parts liquid nitrile rubber, and 440 parts quartz fine sand.

[0062] The difference between Comparative Example 2 and Example 4 is that the addition of basalt fiber is omitted.

[0063] Comparative Example 3

[0064] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts modified basalt fiber.

[0065] The difference between Comparative Example 3 and Example 4 is that the addition of diatomaceous earth is omitted.

[0066] Comparative Example 4

[0067] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts modified carbon fiber-diatomite composite filler, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts basalt fiber.

[0068] The difference between Comparative Example 4 and Example 4 is that the modification operation on basalt fibers was omitted, and the commercially available product was directly applied to high-toughness and high-strength concrete.

[0069] Comparative Example 5

[0070] A high-toughness and high-strength concrete comprises, by weight: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts diatomaceous earth, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts modified basalt fiber.

[0071] The difference between Comparative Example 2 and Example 4 is that the modification operation on diatomaceous earth was omitted, and the commercially available product was directly applied to high-toughness and high-strength concrete.

[0072] Test case

[0073] Early crack resistance: Standard test blocks (800mm×600mm×100mm) were made from the crack-resistant building materials prepared in Examples 1-5 and Comparative Examples 1-5. 24 hours after concrete pouring, the number of cracks per unit area and the total cracked area per unit area were measured according to GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The test results are shown in Table 1.

[0074] Table 1

[0075]

[0076] The compressive strength was tested in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete";

[0077] The flexural tensile strength was tested using the four-point flexural test method, in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0078] The equivalent flexural strength was tested in accordance with CECS13:2009 "Standard Test Methods for Fiber Reinforced Concrete" to characterize the toughness of high-strength and tough concrete.

[0079] Referring to the ACI 544.2R-89 test method for concrete impact compression properties, an impact test device was used to conduct the impact performance test. The mass of the drop hammer was 4.5 kg, and the impact elevation of the free fall hammer was h = 475 mm. During the test, the impact ball was pulled up to the specified height and then released, and the impact ball fell freely to impact the concrete specimen. When the first visible crack appeared on the surface of the concrete specimen, the number of impacts was recorded as the initial crack impact number N1. The impact energy J required for the first visible crack to appear was calculated.

[0080] Preparation of concrete test specimens: The high-toughness, high-strength concrete of Examples 1-5 and Comparative Examples 1-5 were poured and molded. During the pouring process, the high-toughness, high-strength concrete slurry was used to fill the manhole cover molds. After vibration for 10 minutes using a cement vibrator, the molds were placed in a curing room for 28 hours. After demolding, the specimens were placed in standard water at room temperature for 28 days to obtain the test specimens. The humidity of the curing room was 90-95%, and the temperature was 24-25 degrees Celsius.

[0081] The test results are shown in Table 2:

[0082]

[0083] Comprehensive performance analysis: Comparative Example 1 uses commercially available diatomaceous earth and basalt fiber, which has poor early crack resistance. This indicates that unmodified fibers and fillers may cause defects in concrete due to poor interface, thus making the improvement of concrete crack resistance by Comparative Example 1 extremely limited. Furthermore, as shown in Table 2, the performance indicators of Comparative Example 1 are significantly lagging behind, indicating that unmodified fillers and fibers cannot effectively perform the task of reinforcing concrete.

[0084] Comparative Example 2 omitted the addition of basalt fiber but contained composite filler. Its performance was significantly improved compared to Comparative Example 1, but still significantly weaker than Example 4. It was superior to Comparative Example 1, possibly because: the modified basalt fiber in the component, after being modified with myristyltrimethylammonium bromide, has a steric hindrance effect due to its long carbon chain and electrostatic repulsion of the positively charged head groups. This can prevent the basalt fiber from agglomerating during mixing with epoxy resin, making the fiber dispersion more uniform and improving the load-bearing capacity of the material. Furthermore, after modification with N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, the methoxy group hydrolyzes to generate active silanol groups, which can undergo a condensation reaction with the hydroxyl groups on the surface of the basalt fiber to form stable covalent bonds. This allows the stress to be effectively transferred to the high-strength basalt fiber when the concrete is under stress, allowing the fiber to fully exert its load-bearing capacity. It also avoids premature separation of the fiber from the matrix under external force, thus delaying material failure and improving the toughness and impact resistance of the material.

[0085] Comparative Example 3 omitted the addition of filler but contained basalt fiber. Due to the lack of filler, its 28-day compressive strength was poor, but its flexural tensile strength and early crack resistance were superior to other comparative examples. This may be due to the modified carbon fiber-diatomaceous earth composite filler in the composition. The carbon fiber itself has high strength and high modulus, playing a role in reinforcing and bridging cracks in concrete. The carbon fiber was treated with KH-550 silane coupling agent, which significantly improved the interfacial compatibility and bond strength between the carbon fiber and the epoxy resin matrix, ensuring that stress could be effectively transferred from the matrix to the carbon fiber, fully utilizing the reinforcing potential of the carbon fiber. The KH-550-treated carbon fiber was mixed with diatomaceous earth, which has a porous structure and a large specific surface area. This facilitated further dispersion of the KH-550 modified carbon fiber in the epoxy matrix, reducing agglomeration and forming a more uniform reinforcing network. Furthermore, the porous structure and irregular morphology of diatomaceous earth could form a microscopic mechanical interlocking effect at the interface between the carbon fiber, diatomaceous earth, and epoxy matrix, further enhancing the interfacial bonding. This allows the porous structure of the composite filler to absorb some energy through its own micro-fracture or deformation when subjected to impact, thereby improving the toughness of the material.

[0086] Compared to Comparative Example 3, Comparative Example 5 added commercially available diatomaceous earth, and Comparative Example 4 added commercially available basalt fiber compared to Comparative Example 2. Although their various properties were slightly improved, there was still a significant performance gap compared to Example 4. The possible reason is that the concrete of this application contains modified carbon fiber-diatomaceous earth composite filler and modified basalt fiber. Under impact load, the two components work together to give the material high compressive strength at the initial stress and to effectively dissipate energy and resist sudden brittle failure when the limit is reached, forming stronger energy absorption and impact resistance. Under the synergistic effect, it can effectively suppress and absorb impact energy when facing various types of stress failure at different stages of development, thereby significantly improving the overall crack resistance and impact resistance of the concrete. This makes the material of this application more suitable for making manhole covers that are frequently subjected to impact.

[0087] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-toughness, high-strength concrete, characterized in that, By weight, it includes: 100-120 parts epoxy resin, 5-10 parts anhydrous ethanol, 25-40 parts T31 curing agent, 25-40 parts modified carbon fiber-diatomite composite filler, 40-60 parts fly ash, 5-10 parts liquid nitrile rubber, 400-450 parts quartz fine sand, and 5-15 parts modified basalt fiber. The modified carbon fiber-diatomite composite filler was prepared by the following method: Ethanol and deionized water were added to a reaction vessel and mixed thoroughly. KH-550 was then added and continuously stirred. Carbon fibers were then weighed and placed into the reaction vessel, ensuring that all carbon fibers were completely submerged in the solution. The container was then sealed and left to soak at room temperature for 8 hours. After soaking for 8 hours, excess solution was discarded, and the removed carbon fibers were evenly spread out and air-dried in a well-ventilated area for 1-2 hours, thus obtaining KH-550 modified carbon fibers. The KH-550 modified carbon fibers were then placed in a mortar and diatomite were added. The mixture was gently and thoroughly stirred using a pestle. After stirring evenly, the mixture was spread out in a container and allowed to air-dry for 12 hours, thus obtaining the modified carbon fiber-diatomite composite filler. The modified basalt fiber was prepared by the following method: Deionized water and myristyltrimethylammonium bromide were added to a reaction vessel, the temperature was raised to 60°C, and the mixture was magnetically stirred for 30 min; then the stirring was stopped, and pretreated basalt fiber was added to the reaction vessel, fully submerged, and impregnated for 6 h; then the mixture was filtered and repeatedly rinsed with deionized water, and dried to constant weight to obtain an intermediate product; anhydrous ethanol and deionized water were added to a reaction vessel, and then N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane was added, the temperature was raised to 60°C, and the mixture was magnetically stirred for 30 min; then the intermediate product was added to the reaction vessel, fully submerged, and impregnated for 6 h; then the mixture was filtered and repeatedly rinsed with anhydrous ethanol, and finally the final product was placed in a drying oven at 80°C and dried for 12 h to obtain the self-made modified basalt fiber.

2. The high-toughness, high-strength concrete according to claim 1, characterized in that, By weight, it includes: 115 parts epoxy resin, 8 parts anhydrous ethanol, 36 parts T31 curing agent, 36 parts modified carbon fiber-diatomite composite filler, 55 parts fly ash, 8 parts liquid nitrile rubber, 440 parts quartz fine sand, and 12 parts modified basalt fiber.

3. The high-toughness, high-strength concrete according to claim 1, characterized in that, The fineness modulus of the quartz sand is 2.4-2.7, and the particle size is 2-5 mm.

4. The high-toughness, high-strength concrete according to claim 1, characterized in that, The fly ash is Class I ash with a specific surface area ≥350m². 2 / kg.

5. The high-toughness, high-strength concrete according to claim 1, characterized in that, The epoxy resin is bisphenol A type E44 epoxy resin.

6. The high-toughness, high-strength concrete according to claim 1, characterized in that, The carbon fiber is a short-cut carbon fiber with an average diameter of 10μm and a length of 1-2cm.

7. The high-toughness, high-strength concrete according to claim 1, characterized in that, The pretreatment method for the basalt fiber is as follows: the basalt fiber is placed in a muffle furnace for heat treatment; after cooling in the furnace, it is placed in a 1 mol / L hydrochloric acid solution and heated to 80 degrees Celsius for acid washing for 5 hours; then filtered and the basalt fiber is repeatedly rinsed until the pH of the filtrate is 7. The basalt fiber is then collected and dried to constant weight to obtain the pretreated basalt fiber.

8. The high-toughness, high-strength concrete according to claim 7, characterized in that, The heat treatment temperature of the muffle furnace is set to 500℃.

9. A manhole cover, characterized in that: It includes a steel reinforcement skeleton and a concrete cover filled in the steel reinforcement skeleton, wherein the concrete cover is made of high-toughness and high-strength concrete as described in any one of claims 1-8.

10. A method for preparing a manhole cover, used to prepare a manhole cover as described in claim 9, characterized in that, Includes the following steps: Epoxy resin, anhydrous ethanol, modified carbon fiber-diatomite composite filler, fly ash, liquid nitrile rubber, quartz fine sand, and modified basalt fiber are added to a mixing container in sequence and stirred evenly for 2-3 minutes until completely mixed. Then, T31 curing agent is added and stirring is continued for 3-5 minutes until evenly dispersed to obtain high-toughness and high-strength concrete. The reinforcing steel skeleton is placed in a mold, and then high-toughness and high-strength concrete is filled into the reinforcing steel skeleton. After being vibrated evenly, it is cured for 28 hours and then demolded to obtain the manhole cover.

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