Impact-resistant concrete and its preparation method

Abstract

The application relates to the technical field of concrete, and particularly discloses an impact-resistant concrete and a preparation method thereof. The impact-resistant concrete comprises the following raw materials in parts by weight: cement 100-200 parts, coarse aggregate 400-500 parts, fine aggregate 200-400 parts, water 100-300 parts, water reducing agent 3-20 parts, mixed fiber material 60-100 parts and modified epoxy resin 40-60 parts; the mixed fiber material is a mixture of steel fibers and organic fibers; the modified epoxy resin is SiO2 modified epoxy resin; the impact-resistant concrete has an impact strength of 50.1 MPa, a 7d compressive strength of 37.5 MPa and a 28d compressive strength of 59.9 MPa, and the impact resistance of the concrete is improved.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and more specifically, to an impact-resistant concrete and a method for preparing the same. Background Technology

[0002] Concrete is an artificial stone material made by mixing cementitious materials, granular aggregates (also known as aggregates), water, and, if necessary, admixtures and additives in a certain proportion, uniformly mixing, compacting, and curing.

[0003] Concrete is widely used in engineering due to its abundant raw materials, ease of sourcing, simple molding, low cost, and compatibility with steel to create various load-bearing components. However, concrete is prone to brittle fracture and spalling under impact loads. As the engineering economy develops and demands for engineering quality increase, the requirements for concrete are also rising, particularly regarding its impact resistance. Therefore, designing a type of concrete with excellent impact resistance is a pressing issue that needs to be addressed in this field. Summary of the Invention

[0004] To improve the impact resistance of concrete, this application provides an impact-resistant concrete and a method for preparing the same.

[0005] In a first aspect, this application provides an impact-resistant concrete, which adopts the following technical solution:

[0006] An impact-resistant concrete comprises the following raw materials in parts by weight: 100-200 parts cement, 400-500 parts coarse aggregate, 200-400 parts fine aggregate, 100-300 parts water, 3-20 parts water-reducing agent, 60-100 parts mixed fiber material, and 40-60 parts modified epoxy resin.

[0007] The mixed fiber material is a mixture of steel fibers and organic fibers;

[0008] The modified epoxy resin is a SiO2 modified epoxy resin.

[0009] This application describes impact-resistant concrete comprising the following raw materials by weight: 100-200 parts cement, 400-500 parts coarse aggregate, 200-400 parts fine aggregate, 100-300 parts water, 3-20 parts water-reducing agent, 60-100 parts mixed fiber material, and 40-60 parts modified epoxy resin. Any value within the respective range of concrete raw materials can be used to improve the impact resistance of the concrete. The optimal combination is 150 parts cement, 450 parts coarse aggregate, 300 parts fine aggregate, 200 parts water, 12 parts water-reducing agent, 80 parts mixed fiber material, and 50 parts modified epoxy resin.

[0010] By adopting the above technical solution, cement, coarse aggregate, fine aggregate, and water are used as the concrete base material, and water-reducing agent, mixed fiber material, and modified epoxy resin are used as reinforcing materials. Among them, the water-reducing agent can have a dispersing effect and has the functions of water retention, superplasticization, water reduction, and reinforcement, which can improve the compressive strength and impact strength of concrete. The mixed fiber material can improve the brittleness of concrete, improve the toughness of concrete, and effectively improve the impact resistance of concrete. At the same time, the water-reducing agent can give fiber concrete good workability and improve its workability, improve the early strength of concrete, and prevent early cracking of concrete.

[0011] In concrete, fibers primarily function to bridge cracks and alleviate stress concentration at crack tips. Using a mixture of steel and organic fibers as a hybrid fiber material allows for a synergistic effect, with fibers complementing each other's performance advantages. This progressive reinforcement and toughening occurs at different structural levels and loading stages, leveraging the hybrid and scale effects of the fibers to enhance tensile and impact resistance. Steel fibers effectively reduce stress concentration at initial defects within the concrete matrix, inhibiting crack initiation and propagation through bridging. Organic fibers primarily improve the internal structure of concrete, effectively eliminating or mitigating the occurrence and development of early-stage cracks, blunting stress concentration at crack tips, and making the stress field within the concrete matrix more continuous and uniform. Simultaneously, organic fibers bridge microcracks distributed within the concrete and inhibit their development into macrocracks.

[0012] Modified epoxy resin using SiO2 improves the interfacial bonding force between epoxy resin and nano-SiO2, increases the dispersibility and dispersion stability of SiO2 in the matrix, and effectively improves the viscosity and dispersibility of the epoxy resin matrix. When the matrix is ​​subjected to impact, the particles and the matrix also undergo plastic deformation to absorb impact energy, thereby achieving the effect of strengthening and toughening, and thus improving the impact resistance of concrete.

[0013] Therefore, the various raw materials in this application work together to achieve a synergistic effect, thereby improving the impact resistance of concrete.

[0014] Preferably, the SiO2-modified epoxy resin comprises, by weight, 40-60 parts epoxy resin, 20-40 parts nano-SiO2, 10-15 parts water-based curing agent, 3-10 parts reactive diluent, 10-30 parts silane coupling agent, 0.5-5 parts acetone, 10-20 parts vinyl monomer, 0.5-3 parts initiator, 5-10 parts emulsifier, and 10-15 parts water.

[0015] This application describes a SiO2-modified epoxy resin comprising the following raw materials in parts by weight: 40-60 parts epoxy resin, 20-40 parts nano-SiO2, 10-15 parts water-based curing agent, 3-10 parts reactive diluent, 10-30 parts silane coupling agent, 0.5-5 parts acetone, 10-20 parts vinyl monomer, 0.5-3 parts initiator, 5-10 parts emulsifier, and 10-15 parts water. The SiO2-modified epoxy resin raw materials can be selected from any value within their respective ranges, and can improve the impact resistance of concrete.

[0016] Preferably, the SiO2-modified epoxy resin is prepared as follows:

[0017] (1) Mix silane coupling agent, nano-SiO2 and acetone, heat to 40-70℃, stir, wash and dry to obtain silane modified SiO2;

[0018] (2) Under alkaline conditions, silane-modified SiO2 and emulsifier were added to water, ultrasonically dispersed, and vinyl monomers and initiators were added and mixed. The mixture was then reacted at 75℃-95℃ to obtain vinyl polymer-coated nano-SiO2.

[0019] (3) Add epoxy resin and reactive diluent to vinyl polymer-coated nano-SiO2, mix, add water-based curing agent and let stand to obtain the final product.

[0020] By adopting the above technical solution, silane-modified nano-SiO2 is coated with a vinyl polymer and then combined with epoxy resin. Surface treatment of the nano-SiO2 using a silane coupling agent improves the interfacial bonding force between the epoxy resin and the nano-SiO2, increases the dispersibility and dispersion stability of SiO2 in the matrix, and enhances the compatibility between the nanoparticles and the polymer, resulting in a more uniform mixing of the composite material. The vinyl polymer-coated nano-SiO2 used to modify epoxy resin can effectively improve the viscosity and dispersibility of the epoxy resin matrix, thereby improving the flexibility of the material and achieving the effect of strengthening and toughening, further enhancing the impact resistance of concrete.

[0021] Preferably, the epoxy resin is a carboxyl-terminated hyperbranched polyester epoxy resin, and the preparation method of the carboxyl-terminated hyperbranched polyester epoxy resin is as follows:

[0022] (1) Under the protection of an inert gas, 16-20 kg of acid anhydride and 16-20 kg of ethylene glycol are added to 150-190 kg of methanol and heated to 30-50 °C under stirring. Then, 2-5 kg ​​of acid anhydride and 0.1-1 kg of tetrabutyl titanate are added and heated to 50-80 °C to react. Then, the mixture is dried to obtain a carboxyl-terminated hyperbranched polyester.

[0023] (2) Add the carboxyl-terminated hyperbranched polyester prepared in step (1), 5-10 kg of triethylamine, and 100-140 kg of epichlorohydrin to 100-130 kg of acetonitrile, heat to 55-75 °C and react, then add 80-120 kg of bisphenol A type epoxy resin and 5-15 kg of diethylenetriamine and heat to 75-85 °C to react to obtain the product.

[0024] By adopting the above technical solution, the epoxy resin is a carboxyl-terminated hyperbranched polyester epoxy resin. The reason is that the hyperbranched polyester molecule has a large amount of free volume, which can absorb and mitigate impact energy. Moreover, the carboxyl terminus enables the carboxyl-terminated hyperbranched polyester to be well miscible with the epoxy resin, thereby increasing the crosslinking density of the carboxyl-terminated hyperbranched polyester epoxy resin, increasing solubility and reducing viscosity. At the same time, it absorbs impact energy when concrete is impacted, thereby achieving the purpose of toughening. Therefore, it can further improve the impact resistance of concrete.

[0025] Preferably, the weight ratio of the water-reducing agent to the mixed fiber material is 1:(8-10).

[0026] By adopting the above technical solution and adjusting the weight ratio of water-reducing agent and mixed fiber material, the impact resistance of concrete can be further improved.

[0027] Preferably, the organic fiber is a mixture of polypropylene fiber and polyvinyl alcohol fiber.

[0028] By adopting the above technical solutions, polypropylene fibers have excellent early crack prevention and late crack restriction performance, targeting large but few cracks and strengthening the compactness of concrete. Polyvinyl alcohol fibers can form a random support system inside the concrete, which can effectively prevent the formation of plastic shrinkage and drying shrinkage cracks in concrete. That is, the crack resistance of polyvinyl alcohol fibers is mainly aimed at small but numerous cracks. Although polypropylene fibers and polyvinyl alcohol fibers have small elastic moduli, they are numerous and have a very large deformation elongation rate. During the tensile deformation elongation process, they will consume a lot of energy. The combined effect of the two prevents the cracking of concrete from the root and improves the impact toughness.

[0029] Therefore, steel fibers, polypropylene fibers, and polyvinyl alcohol fibers work synergistically to enhance and toughen concrete, thereby further improving its impact resistance.

[0030] Preferably, the weight ratio of the polypropylene fiber to the polyvinyl alcohol fiber is (2-4):1.

[0031] By adopting the above technical solution and adjusting the weight ratio of polypropylene fiber and polyvinyl alcohol fiber, the impact resistance of concrete can be further improved.

[0032] Preferably, the water-reducing agent is a polycarboxylate water-reducing agent.

[0033] By adopting the above technical solution, the use of polycarboxylate superplasticizer in concrete can prevent slump loss without causing significant retardation. Its good fluidity has a significant strengthening effect on concrete, thereby improving the impact resistance of concrete.

[0034] Secondly, this application provides a method for preparing any of the above-mentioned impact-resistant concretes.

[0035] A method for preparing impact-resistant concrete includes the following steps: first, coarse aggregate and fine aggregate are added and mixed; then, cement and steel fibers are added and mixed; then, uniformly mixed organic fibers are added and water is added and mixed; finally, modified epoxy resin and water-reducing agent are added and mixed to obtain the final product.

[0036] In summary, this application includes at least one of the following beneficial technical effects:

[0037] (1) This application adjusts the types and dosages of cement, coarse aggregate, fine aggregate, water, water-reducing agent, mixed fiber material, and modified epoxy resin, and controls the mixed fiber to be a mixture of organic fiber and steel fiber and modifies the epoxy resin to SiO2 modified epoxy resin, so that the impact strength, 7-day compressive strength and 28-day compressive strength of concrete are 50.1 MPa, 37.5 MPa and 59.9 MPa respectively.

[0038] (2) By adjusting the type and weight ratio of organic fibers and steel fibers, this application enables steel fibers, polypropylene fibers and polyvinyl alcohol fibers to work together to prevent concrete from cracking and exert their reinforcing and toughening effects, thereby further improving the impact resistance of concrete, so that the impact strength, 7-day compressive strength and 28-day compressive strength of concrete are 46.5 MPa, 34.8 MPa and 54.5 MPa respectively.

[0039] (3) This application further improves the impact resistance of concrete by adjusting the weight ratio of water-reducing agent and mixed fiber material, resulting in impact strength, 7-day compressive strength and 28-day compressive strength of concrete of 47.65 MPa, 36.1 MPa and 57.1 MPa, respectively. Furthermore, when the water-reducing agent is further modified to be a polycarboxylate water-reducing agent, the impact resistance of concrete is further improved, with impact strength, 7-day compressive strength and 28-day compressive strength of concrete of 48.6 MPa, 37.1 MPa and 59.1 MPa, respectively.

[0040] (4) This application improves the viscosity and dispersibility of the epoxy resin matrix by modifying the epoxy resin with SiO2, and selects the epoxy resin as end-carboxyl hyperbranched polyester epoxy resin, which further improves the impact resistance of concrete, so that the impact strength, 7d compressive strength and 28d compressive strength of concrete are 50.1MPa, 37.5MPa and 59.9MPa respectively. Detailed Implementation

[0041] The present application will be further described in detail below with reference to specific embodiments.

[0042] The following raw materials mentioned in this application are all commercially available products and are intended to fully disclose the raw materials in this application; they should not be construed as limiting the source of the raw materials. Specifically:

[0043] The coarse aggregate is crushed stone with a particle size of 5-15mm; the fine aggregate is quartz sand with a mud content of 2%, a mud lump content of 0.2%, and a fineness modulus of 2.5; the cement is P.O42.5 ordinary Portland cement; the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent with a water reduction rate of 45% and an air content of 4.0%, and a naphthalene-based water-reducing agent is also selected with a water reduction rate of 32% and an air content of 2.2%; the steel fibers are end-hooked, with a compressive strength of 800MPa, a length of 25mm, and a diameter of 0.75mm; the polypropylene fibers have a compressive strength of 1200MPa and a length of 9mm; the polyvinyl alcohol fibers have a compressive strength of 500MPa and a length of 5mm. The epoxy resin selected is E51, with an epoxy equivalent (g / mol) of 184-195 and a viscosity (25℃) of 10000-16000 mPa·s; the bisphenol A type epoxy resin selected is 128, with a density (ρ25) of 1.36 g / cm³. 3 Viscosity (25℃) is 10000-14000 mPa·s, content is 99%, industrial grade; the water-based curing agent is caprolactam, density is 1.01 g / cm³. 3 The purity is 99.5%; the reactive diluent is epichlorohydrin with a density of 1.18 g / cm³. 3 The purity is 99.5%; the silane coupling agent used is trivinylsilane, model A-151, with a density (ρ20) of 1.0350 ± 0.005 g / cm³. 3 The product has a purity of 99% and is of industrial grade. The vinyl monomer used is butyl methacrylate, with a density of 0.895 g / cm³, also 99% pure and of industrial grade. The initiator used is benzoyl peroxide, with a density (ρ25) of 1.16 g / cm³. 3 The content is 99%, industrial grade; the emulsifier is potassium fatty acid soap, content 99%, industrial grade; the acid anhydride is phthalic anhydride, content 99%, industrial grade.

[0044] The following are examples of the preparation of SiO2 modified epoxy resin.

[0045] Preparation Example 1

[0046] The SiO2-modified epoxy resin of Preparation Example 1 was prepared by the following steps:

[0047] (1) Add 20 kg of trivinylsilane to 2.6 kg of acetone, stir and mix evenly, then add 30 kg of nano-SiO2, heat to 55 °C, react at 500 rpm for 2 h, wash with methanol, and vacuum dry to obtain 28 kg of silane-modified SiO2; (2) Add 28 kg of silane-modified SiO2 and 8 kg of potassium fatty acid soap to 13 kg of water, add 5 kg of CaCO3, ultrasonically disperse for 30 min, add 15 kg of butyl methacrylate and 1.7 kg of benzoyl peroxide, mix and stir evenly, react at 85 °C for 5 h to obtain 20 kg of vinyl polymer-coated nano-SiO2;

[0048] (3) Add 50 kg of epoxy resin and 7 kg of epichlorohydrin to 20 kg of vinyl polymer-coated nano-SiO2 and mix for 1 h. Add 7 kg of caprolactam and stir for 30 min. Let stand for 6 h to obtain the final product.

[0049] Preparation Examples 2-3

[0050] The preparation methods of the SiO2 modified epoxy resins in Preparation Examples 2-3 are the same as those in Preparation Example 1. The difference is that the amount of vinyl polymer coated with nano-SiO2 in step (3) of the preparation of SiO2 modified epoxy resin is different. The amount of vinyl polymer coated with nano-SiO2 is 5 kg and 10 kg, respectively. The other raw materials are the same as those in Preparation Example 1.

[0051] Preparation Example 4

[0052] The SiO2-modified epoxy resin in Preparation Example 4 was prepared using the same method as in Preparation Example 1, except that 50 kg of epoxy resin was replaced with 50 kg of carboxyl-terminated hyperbranched polyester epoxy resin. The types and amounts of other raw materials were the same as in Preparation Example 1. The preparation method of the carboxyl-terminated hyperbranched polyester epoxy resin is as follows:

[0053] (1) Under N2 gas protection, 18 kg of phthalic anhydride was added to 170 kg of dimethyl sulfoxide and stirred at 500 rpm until homogeneous. Then, 18 kg of ethylene glycol was added while stirring, and the mixture was heated to 40 °C and reacted for 4 h. Then, 4 kg of phthalic anhydride and 0.6 kg of tetrabutyl titanate were added, and the mixture was heated to 65 °C and reacted for 2 h. Then, the mixture was vacuum dried for 12 h to obtain 57 kg of carboxyl-terminated hyperbranched polyester.

[0054] (2) 57 kg of carboxyl-terminated hyperbranched polyester was added to 115 kg of acetonitrile. After stirring at 500 rpm, 8 kg of triethylamine and 120 kg of epichlorohydrin were added while stirring. The mixture was then heated to 65 °C and reacted for 2.5 h. 100 kg of bisphenol A epoxy resin and 10 kg of diethylenetriamine were then added. The mixture was then heated to 80 °C and reacted for 1.5 h to obtain 71 kg of carboxyl-terminated hyperbranched polyester epoxy resin.

[0055] Preparation Examples 5-6

[0056] The SiO2-modified epoxy resins prepared in Examples 5-6 were prepared using the same method as those prepared in Example 4. The difference was that the amount of bisphenol A type epoxy resin used in the preparation of the carboxyl-terminated hyperbranched polyester epoxy resin was 80 kg and 120 kg, respectively, while the types and amounts of other raw materials were the same as those in Example 4.

[0057] Example 1

[0058] The impact-resistant concrete of Example 1 was prepared by the following method:

[0059] According to the dosage in Table 1, the organic fibers were first stirred and dispersed evenly for later use. The mixer was then turned on, and coarse and fine aggregates were added and mixed evenly. Then, cement and steel fibers were added and mixed evenly. Next, the already mixed organic fibers were added, followed by water and stirring. Finally, SiO2-modified epoxy resin and water-reducing agent were added and mixed evenly to obtain impact-resistant concrete. The SiO2-modified epoxy resin used was the one prepared in Preparation Example 1.

[0060] Examples 2-8

[0061] The preparation methods of the impact-resistant concrete in Examples 2-8 are the same as those in Example 1, except that the raw material admixtures are different, as detailed in Table 1.

[0062] Table 1. Dosage of each raw material in impact-resistant concrete (Examples 1-8) (kg)

[0063]

[0064]

[0065] Examples 9-12

[0066] The preparation methods of impact-resistant concrete in Examples 9-12 are the same as those in Example 7, except that the amount of water-reducing agent used in the raw material admixtures is different. The other types and amounts of raw materials are the same as in Example 7, as detailed in Table 2.

[0067] Table 2. Dosage (kg) of each raw material in impact-resistant concrete for Examples 9-12

[0068]

[0069] Example 13

[0070] The preparation method of the impact-resistant concrete in Example 13 is the same as that in Example 11, except that the naphthalene-based water-reducing agent is replaced with an equal amount of polycarboxylate water-reducing agent, and the other raw materials and dosages are the same as in Example 11.

[0071] Examples 14-15

[0072] The preparation method of the impact-resistant concrete in Examples 14-15 is the same as that in Example 13, except that the amount of modified epoxy resin is different. The SiO2 modified epoxy resin dosage is 40 kg and 60 kg respectively, and the dosage of other raw materials is the same as in Example 13.

[0073] Examples 16-20

[0074] The preparation methods of the impact-resistant concrete in Examples 16-20 are the same as those in Example 13, except that the modified epoxy resin used is the SiO2 modified epoxy resin prepared in Examples 2-6, and the types and amounts of other raw materials are the same as in Example 13.

[0075] Comparative Example 1

[0076] The preparation method of the impact-resistant concrete in Comparative Example 1 is the same as that in Example 1, except that the polypropylene fibers are replaced with steel fibers in equal amounts, while the other raw materials and dosages are the same as in Example 1.

[0077] Comparative Example 2

[0078] The preparation method of the impact-resistant concrete in Comparative Example 2 is the same as that in Example 1, except that steel fibers are replaced with polypropylene fibers in equal amounts, while the other raw materials and dosages are the same as in Example 1.

[0079] Comparative Example 3

[0080] The preparation method of the impact-resistant concrete in Comparative Example 3 is the same as that in Example 1, except that the amount of polypropylene fiber is 60 kg, the amount of polyvinyl alcohol fiber is 20 kg, and no steel fiber is added. The other raw materials and their amounts are the same as in Example 1.

[0081] Comparative Example 4

[0082] The preparation method of the impact-resistant concrete in Comparative Example 4 is the same as that in Example 1, except that polypropylene fibers are replaced with carbon fibers in equal amounts, while the other raw materials and dosages are the same as in Example 1.

[0083] Comparative Example 5

[0084] The preparation method of the impact-resistant concrete in Comparative Example 5 is the same as that in Example 1, except that the SiO2 modified epoxy resin is replaced with an equal amount of unmodified epoxy resin, and the other raw materials and dosages are the same as in Example 1.

[0085] Performance testing

[0086] The impact-resistant concretes obtained in different Examples 1-20 and Comparative Examples 1-5 were tested using the following testing standards or methods. The test results are detailed in Table 3.

[0087] Impact strength, 7-day compressive strength and 28-day compressive strength: The impact strength, 7-day compressive strength and 28-day compressive strength of impact-resistant concrete were tested in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The test results are detailed in Table 3.

[0088] Impact performance uniformity test: 30 points at different locations were randomly selected on the concrete after 28 days of curing to test the impact resistance. The standard deviation of the 30 data points was then calculated. A standard deviation > 0.5 indicates uneven impact performance distribution; a standard deviation ≤ 0.5 indicates uniform impact performance distribution.

[0089] Table 3 Performance test results of different impact-resistant concretes

[0090]

[0091]

[0092] The test results in Table 3 show that the impact-resistant concrete obtained in this application has the highest impact strength, 7-day compressive strength and 28-day compressive strength of 50.1 MPa, 37.5 MPa and 59.9 MPa, respectively, which have high mechanical properties and uniform impact performance distribution, thus improving the impact resistance of the impact-resistant concrete.

[0093] In Examples 1-3, the impact strength, 7-day compressive strength and 28-day compressive strength of the impact-resistant concrete obtained in Example 1 were 44.9 MPa, 32.9 MPa and 50.7 MPa, respectively, which were all higher than those in Examples 2 and 3. This indicates that controlling the weight proportions of steel fibers and organic fibers improved the impact resistance of the concrete.

[0094] Performance test data of the impact-resistant concrete in Examples 4-8 revealed that the impact strength, 7-day compressive strength, and 28-day compressive strength of the concrete obtained in Examples 6-8 were 45.9-46.5 MPa, 34.1-34.8 MPa, and 53.1-54.5 MPa, respectively, all higher than those in Examples 4 and 5. This indicates that a weight ratio of (2-4):1 for polypropylene fiber and polyvinyl alcohol fiber is more suitable, improving the impact resistance of the concrete. This may be related to the synergistic effect of organic fibers and steel fibers, which can effectively prevent the generation and propagation of concrete cracks. The combination of steel fibers with polypropylene fibers and polyvinyl alcohol fibers can play a reinforcing and toughening role, thus improving the impact resistance of concrete.

[0095] Combining the performance test data of impact-resistant concrete from Examples 7 and 9-12, it was found that the impact strength, 7-day compressive strength, and 28-day compressive strength of the concrete obtained in Examples 10-12 were 47.1-47.6 MPa, 35.3-36.1 MPa, and 55.5-57.1 MPa, respectively, all higher than those of Examples 7 and 9. A weight ratio of 1:(8-10) for the water-reducing agent and mixed fiber material was deemed suitable, improving the impact resistance of the concrete. This may be related to the water-reducing agent's ability to impart good workability to the fiber-reinforced concrete, improve its workability, enhance its early strength, and prevent early cracking.

[0096] Combining the performance test data of the impact-resistant concrete from Examples 11 and 13, it was found that the impact strength, 7-day compressive strength, and 28-day compressive strength of the concrete obtained in Example 13 were 48.6 MPa, 36.8 MPa, and 58.5 MPa, respectively, which were higher than those of Example 11. This indicates that polycarboxylate superplasticizer is more suitable as it improves the impact resistance of the concrete. This may be related to the fact that polycarboxylate superplasticizer can significantly strengthen the concrete.

[0097] Combining the performance test data of the impact-resistant concrete from Examples 13 and 14-15, it was found that the impact strength, 7-day compressive strength, and 28-day compressive strength of the concrete obtained in Example 13 were 48.6 MPa, 36.8 MPa, and 58.5 MPa, respectively, all higher than those of Examples 14-15. This indicates that the dosage of SiO2-modified epoxy resin in Example 13 was appropriate, improving the impact resistance of the concrete. This may be related to the fact that SiO2-modified epoxy resin can improve the viscosity and dispersibility of the epoxy resin matrix, and the increased crosslinking density of the carboxyl-terminated hyperbranched polyester epoxy resin, both of which contribute to the strengthening and toughening effect of the concrete, further improving its impact resistance.

[0098] Combining the performance test data of impact-resistant concrete in Examples 13 and 16-20, it was found that the impact strength, 7-day compressive strength and 28-day compressive strength of the concrete obtained in Example 13 were 48.6 MPa, 36.8 MPa and 58.5 MPa, respectively, which were higher than those in Examples 16-17. This indicates that the amount of vinyl polymer coated with nano-SiO2 in step (3) of SiO2 modified epoxy resin in Example 13 was appropriate, which improved the impact resistance of the concrete.

[0099] Meanwhile, the impact strength, 7-day compressive strength and 28-day compressive strength of the impact-resistant concrete obtained in Example 18 were 50.1 MPa, 37.5 MPa and 59.9 MPa, respectively, which were also higher than those in Examples 19-20. This indicates that the amount of bisphenol A type epoxy resin used in the preparation of end-carboxyl hyperbranched polyester epoxy resin in Example 18 was appropriate, which improved the impact resistance of the concrete.

[0100] Furthermore, based on the data of various indicators of concrete from Comparative Examples 1-5 and Example 1, it was found that the addition of SiO2-modified epoxy resin and mixed fiber materials to the impact-resistant concrete raw materials of this application can improve the impact resistance of concrete to varying degrees.

[0101] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A shock-resistant concrete, characterized by, The raw materials include cement 100-200 parts, coarse aggregate 400-500 parts, fine aggregate 200-400 parts, water 100-300 parts, water reducing agent 3-20 parts, mixed fiber material 60-100 parts, and modified epoxy resin 40-60 parts by weight; The mixed fiber material is a mixture of steel fiber and organic fiber, the organic fiber is a mixture of polypropylene fiber and polyvinyl alcohol fiber, and the weight ratio of the polypropylene fiber to the polyvinyl alcohol fiber is (2-4):1; The modified epoxy resin is SiO2 modified epoxy resin, and the raw materials include epoxy resin 40-60 parts, nano SiO2 20-40 parts, water-based curing agent 10-15 parts, active diluent 3-10 parts, silane coupling agent 10-30 parts, acetone 0.5-5 parts, vinyl monomer 10-20 parts, initiator 0.5-3 parts, emulsifier 5-10 parts, and water 10-15 parts by weight; The preparation method of the SiO2 modified epoxy resin is as follows: (1) mixing silane coupling agent, nano SiO2 and acetone, stirring and drying at 40-70℃ to obtain silane modified SiO2; (2) under alkaline conditions, adding the silane modified SiO2 and emulsifier into water, ultrasonic dispersion, adding vinyl monomer and initiator, mixing, and then reacting at 75-95℃ to obtain vinyl polymer coated nano SiO2; (3) adding epoxy resin and active diluent into the vinyl polymer coated nano SiO2, and adding water-based curing agent and standing to obtain the product; The epoxy resin is carboxyl-terminated hyperbranched polyester epoxy resin, and the preparation method of the carboxyl-terminated hyperbranched polyester epoxy resin is as follows: (1) under inert gas protection, adding 16-20 kg of anhydride and 16-20 kg of ethylene glycol into 150-190 kg of methanol, stirring and heating to 30-50℃, then adding 2-5 kg of anhydride and 0.1-1 kg of butyl titanate, heating to 50-80℃, and then drying to obtain carboxyl-terminated hyperbranched polyester; (2) adding the carboxyl-terminated hyperbranched polyester prepared in step (1), 5-10 kg of triethylamine, and 100-140 kg of epoxy chloropropane into 100-130 kg of acetonitrile, heating to 55-75℃, then adding 80-120 kg of bisphenol A type epoxy resin and 5-15 kg of diethylene triamine, heating to 75-85℃, and then obtaining the product.

2. The impact-resistant concrete according to claim 1, wherein The weight ratio of the water reducing agent to the mixed fiber material is 1:(8-10).

3. The impact-resistant concrete according to claim 1, wherein The water reducing agent is polycarboxylic acid water reducing agent.

4. The method of producing impact-resistant concrete according to any one of claims 1 to 3, characterized in that, The method comprises the following operation steps: first adding coarse aggregate and fine aggregate, stirring, then adding cement and steel fiber, stirring, then adding mixed organic fiber, stirring, then adding water, stirring, and finally adding modified epoxy resin and water reducing agent and mixing.

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