High-strength anti-cracking concrete and preparation process thereof
By modifying the composite reinforcement of polyacrylonitrile fiber and graphene oxide, a multi-scale composite reinforcement system is formed, which solves the problem of easy cracking of traditional concrete and improves the crack resistance and mechanical properties.
Patent Information
- Application Number
- CN202510939256.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-08
- Publication Date
- 2025-09-16
AI Technical Summary
Traditional concrete is prone to cracking in complex environments. Existing reinforcement methods make it difficult to balance early strength and long-term crack resistance. In addition, the bonding force between fibers and nanomaterials is insufficient, resulting in high brittleness and uneven dispersion of the material.
A composite reinforcement of modified polyacrylonitrile fiber and graphene oxide is used to optimize the distribution of hydration products through bridging effect and template effect, forming a multi-scale composite reinforcement system to improve the toughness and strength of concrete.
It significantly improves the crack resistance and mechanical properties of concrete, improves the distribution of hydration products, increases the density and stress transfer capacity of the material, and inhibits crack propagation.
Smart Images
Figure SMS_1 
Figure SMS_2 
Figure SMS_3
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of cement preparation, and in particular to high-strength crack-resistant concrete and a preparation process thereof. Background Art
[0002] As one of the most widely used materials in modern construction, the mechanical properties and durability of concrete are directly related to the safety and service life of engineering structures.
[0003] However, conventional concrete suffers from widespread problems in practical applications, including low tensile strength, high brittleness, and susceptibility to cracking. This is particularly true under complex environments such as temperature fluctuations, dry-wet cycles, or long-term loads. The generation and propagation of microcracks can significantly reduce concrete durability and even lead to structural failure. Although recent improvements in concrete performance have been achieved through the addition of fiber materials (such as steel fibers and polypropylene fibers) or nanomaterials (such as nanosilica and carbon nanotubes), these approaches still have significant limitations. For example, conventional fibers have weak interfacial bonding with the cement matrix, making it difficult to effectively inhibit crack propagation. Nanomaterials, due to their large surface area and high surface energy, are prone to agglomeration, resulting in uneven dispersion and potentially acting as stress concentration points, exacerbating material defects. Furthermore, existing technologies often struggle to balance the early strength and long-term crack resistance of concrete by introducing a single reinforcing phase. For example, while some fibers improve toughness, they also reduce flowability, impacting workability. Furthermore, while some chemical admixtures improve workability, their contribution to later strength is limited. What is more noteworthy is that the hydration products of traditional concrete are unevenly distributed, and there are a large number of pores and weak areas in the internal microstructure. These defects will become the source of crack initiation under stress, further accelerating material degradation.
[0004] Therefore, in order to solve the above problems, the present invention provides a high-strength crack-resistant concrete and a preparation process thereof. Summary of the Invention
[0005] The present invention provides a high-strength crack-resistant concrete and a preparation process thereof, which solves the defects in the related art.
[0006] The technical solutions of the present invention are as follows: A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding cement, river sand, and gravel into a mixer, dry-mixing for 2-3 minutes until uniform, then slowly adding a polycarboxylate water reducer and deionized water, wet-mixing for 1-2 minutes, then adding a composite reinforcing agent into the mixer in portions, continuing to stir for 3-5 minutes, and curing to obtain high-strength, crack-resistant concrete.
[0007] More optimally, the high-strength crack-resistant concrete comprises the following components in parts by weight: 100-120 parts of cement, 180-200 parts of river sand, 250-280 parts of crushed stone, 25-40 parts of deionized water, 0.6-0.8 parts of polycarboxylate water-reducing agent, and 1-2 parts of composite reinforcing material.
[0008] More optimally, the composite reinforcement material includes modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 2-3:1.
[0009] More optimally, the preparation process of the modified polyacrylonitrile fiber is: S1: adding polyacrylonitrile fiber to a solution containing benzophenone, methanol and glycidyl methacrylate, soaking for 6-7 minutes, then reacting under ultraviolet light for 15-20 minutes, washing, and drying to obtain epoxidized polyacrylonitrile fiber; S2: adding epoxidized polyacrylonitrile fiber to a hydrazine hydrate aqueous solution, raising the temperature to 80-90°C, reacting for 2-3 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: adding the aminated polyacrylonitrile fiber to an aqueous solution of phosphoric acid and urea, raising the temperature to 60-70° C., reacting for 1-2 hours, washing, and drying to obtain modified polyacrylonitrile fiber.
[0010] In the scheme, benzophenone generates free radicals under ultraviolet light, which trigger the creation of active sites on the surface of polyacrylonitrile fiber. The double bonds in glycidyl methacrylate then combine with the free radicals on the surface of the polyacrylonitrile fiber, causing graft polymerization and introducing epoxy groups (from the glycidyl ester portion of glycidyl methacrylate) onto the surface of the polyacrylonitrile fiber. The specific process is as follows:
[0011] More optimally, the epoxidized polyacrylonitrile fiber raw material comprises the following components: by weight, 100-120 parts of polyacrylonitrile fiber, 5-10 parts of benzophenone, 300-350 parts of methanol, and 20-30 parts of glycidyl methacrylate.
[0012] In the scheme, the hydrazine group attacks the epoxy group with nucleophilicity to obtain aminated polyacrylonitrile fiber. The specific process is as follows:
[0013] More optimally, the aminated polyacrylonitrile fiber raw material comprises the following components: 100-120 parts by weight of epoxidized polyacrylonitrile fiber and 300-350 parts by weight of hydrazine hydrate aqueous solution.
[0014] In the scheme, urea decomposes under heating conditions to generate ammonia, which neutralizes the acidity of phosphoric acid and promotes the condensation of phosphoric acid and amine groups. The amine groups react with phosphoric acid to form ammonium phosphate. The specific reaction process is as follows:
[0015] More optimally, the modified polyacrylonitrile fiber raw material includes the following components: by weight, 100-120 parts of aminated polyacrylonitrile fiber, 30-50 parts of phosphoric acid, 10-20 parts of urea, and 400-450 parts of water.
[0016] Compared with the prior art, the present invention has the following advantages: The present invention forms a multi-scale composite reinforcement system in the concrete matrix through the organic-inorganic synergistic reinforcement effect of modified polyacrylonitrile fiber and graphene oxide, significantly improving the mechanical properties and crack resistance of the material. The details are as follows: First, the introduction of modified polyacrylonitrile fibers and graphene oxide not only fills the micropores in the cement matrix but also optimizes the distribution of hydration products through bridging and template effects. The high aspect ratio of modified polyacrylonitrile fibers enables them to bridge microcracks, inhibiting crack propagation; while the lamellar structure of graphene oxide enhances stress transfer efficiency, resulting in higher toughness and strength under stress.
[0017] Second, the oxygen-containing functional groups of graphene oxide (such as hydroxyl and epoxy groups) accelerate the early hydration reaction of cement, while the modified polyacrylonitrile fiber promotes the uniform distribution of hydration products through the interaction between its surface phosphate groups and calcium ions. The synergistic effect of the two not only increases the hydration rate but also improves the micromorphology of the hydration products, making the material denser.
[0018] Third, the phosphoric acid on the surface of the modified polyacrylonitrile fiber and the oxygen-containing functional groups of graphene oxide form a heterogeneous structure through covalent crosslinking, enhancing the material's internal stress transfer capability. Furthermore, the fiber network of the modified polyacrylonitrile fiber inhibits the aggregation of graphene oxide, ensuring uniform dispersion of the nanomaterial within the matrix. DETAILED DESCRIPTION
[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0020] In the following examples and comparative examples, The cement is commercially available ordinary Portland cement with a PO42.5; The fineness modulus of river sand is 2.79; The particle size of the crushed stone is 5-20mm with continuous grading; The model of polycarboxylate water reducer is HPEG; The length of the polyacrylonitrile fiber is 10 mm.
[0021] Example 1 A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 100 parts of cement, 180 parts of river sand, and 250 parts of crushed stone into a mixer, dry-mixing for 2 minutes until uniform, then slowly adding 0.6 parts of a polycarboxylate water reducer and 25 parts of deionized water, wet-mixing for 1 minute, then adding 1 part of a composite reinforcing agent (comprising modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 2:1) into the mixer in portions, continuing to stir for 3 minutes, and curing to obtain high-strength, crack-resistant concrete. Wherein, the preparation process of modified polyacrylonitrile fiber is: S1: 100 parts of polyacrylonitrile fiber were added to a solution containing 5 parts of benzophenone, 300 parts of methanol and 20 parts of glycidyl methacrylate, and the mixture was immersed for 6 minutes. The mixture was then irradiated with ultraviolet light for 15 minutes, washed and dried to obtain epoxidized polyacrylonitrile fiber. S2: adding 100 parts of epoxidized polyacrylonitrile fiber to 300 parts of hydrazine hydrate aqueous solution, raising the temperature to 80°C, reacting for 2 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: adding 100 parts of aminated polyacrylonitrile fiber to a mixed solution of 30 parts of phosphoric acid, 10 parts of urea, and 400 parts of water, raising the temperature to 60° C., reacting for 1 hour, washing, and drying to obtain modified polyacrylonitrile fiber.
[0022] Example 2 A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 120 parts of cement, 200 parts of river sand, and 280 parts of crushed stone into a mixer, dry-mixing for 3 minutes until uniform, then slowly adding 0.8 parts of a polycarboxylate water reducer and 40 parts of deionized water, wet-mixing for 2 minutes, then adding 2 parts of a composite reinforcing agent (comprising modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 3:1) into the mixer in portions, continuing to stir for 5 minutes, and curing to obtain high-strength, crack-resistant concrete. Wherein, the preparation process of modified polyacrylonitrile fiber is: S1: 120 parts of polyacrylonitrile fiber were added to a solution containing 10 parts of benzophenone, 350 parts of methanol and 30 parts of glycidyl methacrylate, and the mixture was immersed for 7 minutes. The mixture was then irradiated with ultraviolet light for 20 minutes, washed and dried to obtain epoxidized polyacrylonitrile fiber. S2: adding 120 parts of epoxidized polyacrylonitrile fiber to 350 parts of hydrazine hydrate aqueous solution, raising the temperature to 90°C, reacting for 3 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: 120 parts of aminated polyacrylonitrile fiber were added to a mixed solution of 50 parts of phosphoric acid, 20 parts of urea and 450 parts of water, the temperature was raised to 70° C., the mixture was reacted for 2 hours, washed and dried to obtain modified polyacrylonitrile fiber.
[0023] Example 3 A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 110 parts of cement, 190 parts of river sand, and 265 parts of crushed stone into a mixer, dry-mixing for 2.5 minutes until uniform, then slowly adding 0.7 parts of a polycarboxylate water reducer and 32.5 parts of deionized water, wet-mixing for 1.5 minutes, then adding 1.5 parts of a composite reinforcing agent (comprising modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 2.5:1) in portions into the mixer, continuing to stir for 4 minutes, and curing to obtain high-strength, crack-resistant concrete. Wherein, the preparation process of modified polyacrylonitrile fiber is: S1: 110 parts of polyacrylonitrile fiber were added to a solution containing 7.5 parts of benzophenone, 325 parts of methanol and 25 parts of glycidyl methacrylate, and the mixture was immersed for 6.5 minutes. The mixture was then irradiated with ultraviolet light for 17.5 minutes, washed and dried to obtain epoxidized polyacrylonitrile fiber. S2: adding 110 parts of epoxidized polyacrylonitrile fiber to 325 parts of hydrazine hydrate aqueous solution, raising the temperature to 85°C, reacting for 2.5 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: 110 parts of aminated polyacrylonitrile fiber were added to a mixed solution of 40 parts of phosphoric acid, 15 parts of urea and 425 parts of water, the temperature was raised to 65° C., the reaction was carried out for 1.5 hours, the modified polyacrylonitrile fiber was washed and dried to obtain the modified polyacrylonitrile fiber.
[0024] Comparative Example 1 This comparative example does not modify the polyacrylonitrile fiber, and the rest is the same as Example 3, specifically as follows: A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 110 parts of cement, 190 parts of river sand, and 265 parts of crushed stone into a mixer, dry-mixing for 2.5 minutes until uniform, then slowly adding 0.7 parts of a polycarboxylate water reducer and 32.5 parts of deionized water, wet-mixing for 1.5 minutes, then adding 1.5 parts of a composite reinforcing agent (comprising polyacrylonitrile fiber and graphene oxide in a mass ratio of 2.5:1) into the mixer in portions, continuing to stir for 4 minutes, and curing to obtain the high-strength, crack-resistant concrete.
[0025] Comparative Example 2 Graphene oxide is not added to the composite reinforcing agent of this comparative example, and the rest is the same as in Example 3, specifically as follows: A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 110 parts of cement, 190 parts of river sand, and 265 parts of crushed stone into a mixer, dry-mixing for 2.5 minutes until uniform, then slowly adding 0.7 parts of a polycarboxylate water reducer and 32.5 parts of deionized water, wet-mixing for 1.5 minutes, then adding 1.5 parts of modified polyacrylonitrile fiber in portions into the mixer, continuing to stir for 4 minutes, and curing to obtain high-strength, crack-resistant concrete. Wherein, the preparation process of modified polyacrylonitrile fiber is: S1: 110 parts of polyacrylonitrile fiber were added to a solution containing 7.5 parts of benzophenone, 325 parts of methanol and 25 parts of glycidyl methacrylate, and the mixture was immersed for 6.5 minutes. The mixture was then irradiated with ultraviolet light for 17.5 minutes, washed and dried to obtain epoxidized polyacrylonitrile fiber. S2: adding 110 parts of epoxidized polyacrylonitrile fiber to 325 parts of hydrazine hydrate aqueous solution, raising the temperature to 85°C, reacting for 2.5 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: 110 parts of aminated polyacrylonitrile fiber were added to a mixed solution of 40 parts of phosphoric acid, 15 parts of urea and 425 parts of water, the temperature was raised to 65° C., the reaction was carried out for 1.5 hours, the modified polyacrylonitrile fiber was washed and dried to obtain the modified polyacrylonitrile fiber.
[0026] Comparative Example 3 The amount of graphene oxide used in this comparative example is excessive, and the rest is the same as in Example 3, specifically as follows: A method for preparing high-strength, crack-resistant concrete comprises the following steps: adding 110 parts of cement, 190 parts of river sand, and 265 parts of crushed stone into a mixer, dry-mixing for 2.5 minutes until uniform, then slowly adding 0.7 parts of a polycarboxylate water reducer and 32.5 parts of deionized water, wet-mixing for 1.5 minutes, then adding 1.5 parts of a composite reinforcing agent (comprising modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 1:1) in portions into the mixer, continuing to stir for 4 minutes, and curing to obtain the high-strength, crack-resistant concrete. Wherein, the preparation process of modified polyacrylonitrile fiber is: S1: 110 parts of polyacrylonitrile fiber were added to a solution containing 7.5 parts of benzophenone, 325 parts of methanol and 25 parts of glycidyl methacrylate, and the mixture was immersed for 6.5 minutes. The mixture was then irradiated with ultraviolet light for 17.5 minutes, washed and dried to obtain epoxidized polyacrylonitrile fiber. S2: adding 110 parts of epoxidized polyacrylonitrile fiber to 325 parts of hydrazine hydrate aqueous solution, raising the temperature to 85°C, reacting for 2.5 hours, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: 110 parts of aminated polyacrylonitrile fiber were added to a mixed solution of 40 parts of phosphoric acid, 15 parts of urea and 425 parts of water, the temperature was raised to 65° C., the reaction was carried out for 1.5 hours, the modified polyacrylonitrile fiber was washed and dried to obtain the modified polyacrylonitrile fiber.
[0027] Detection experiment: The anti-cracking cement prepared in the examples and comparative examples was cured according to the curing method of the test specimens in GB / T 50081-2019. The curing period was 28 days, and the following performance tests were performed on the cured samples: (1) Determine the compressive strength according to GB / T50081-2019; (2) The above samples were tested for crack resistance. The dimensions of all specimens were 600mm×600mm×50mm. The test temperature was controlled at 25°C. During the test, each specimen with a mold was placed in a wind-blown environment. The cracking condition of each concrete specimen was observed for 24 hours using a feeler gauge specially designed to measure crack width. The obtained data are shown in Table 1 below: Table 1
[0028] Conclusion: This invention successfully produced a high-strength, crack-resistant concrete through organic-inorganic synergy, significantly improving the material's mechanical properties and crack resistance. Experimental results show that concretes using modified polyacrylonitrile fiber and graphene oxide as composite reinforcements (Examples 1-3) exhibit excellent performance, with compressive strength exceeding 62 MPa and no observed cracking.
[0029] In contrast, the compressive strength of concrete containing unmodified polyacrylonitrile fiber (Comparative Example 1) or modified polyacrylonitrile fiber alone (Comparative Example 2) was significantly reduced, and cracking occurred to varying degrees, with maximum crack widths reaching 0.18 mm and 0.12 mm, respectively. Furthermore, while excessive addition of graphene oxide (Comparative Example 3) partially improved crack resistance, it still failed to achieve the optimal ratio, and the compressive strength was lower than that of the example group. This demonstrates that the synergistic effect of modified polyacrylonitrile fiber and graphene oxide is crucial: the modified fiber effectively inhibits crack propagation through its high aspect ratio and surface phosphate groups, while the lamellar structure of graphene oxide optimizes stress transfer and promotes uniform distribution of hydration products. A reasonable ratio of the two (mass ratio 2-3:1) not only enhances the density of concrete, but also improves its toughness and durability.
[0030] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A high-strength crack-resistant concrete, characterized in that: The invention comprises the following components in parts by weight: 100-120 parts of cement, 180-200 parts of river sand, 250-280 parts of crushed stone, 25-40 parts of deionized water, 0.6-0.8 parts of polycarboxylate water reducer, and 1-2 parts of composite reinforcing material; the composite reinforcing material comprises modified polyacrylonitrile fiber and graphene oxide in a mass ratio of 2-3:
1.
2. The high-strength crack-resistant concrete according to claim 1, characterized in that: The preparation process of the modified polyacrylonitrile fiber is as follows: S1: adding polyacrylonitrile fiber to a solution containing benzophenone, methanol and glycidyl methacrylate, soaking for 6-7 minutes, then reacting under ultraviolet light, washing, and drying to obtain epoxidized polyacrylonitrile fiber; S2: adding epoxidized polyacrylonitrile fiber to a hydrazine hydrate aqueous solution, reacting, washing, and drying to obtain aminated polyacrylonitrile fiber; S3: adding the aminated polyacrylonitrile fiber to an aqueous solution of phosphoric acid and urea, reacting, washing, and drying to obtain modified polyacrylonitrile fiber.
3. The high-strength crack-resistant concrete according to claim 2, characterized in that: In step S1, the reaction time is 15-20 minutes.
4. The high-strength crack-resistant concrete according to claim 2, characterized in that: In step S2, the reaction temperature is 80-90° C. and the reaction time is 2-3 h.
5. The high-strength crack-resistant concrete according to claim 2, characterized in that: In step S3, the reaction temperature is 60-70° C. and the reaction time is 1-2 h.
6. The high-strength crack-resistant concrete according to claim 2, characterized in that: The epoxidized polyacrylonitrile fiber raw material comprises the following components: by weight, 100-120 parts of polyacrylonitrile fiber, 5-10 parts of benzophenone, 300-350 parts of methanol, and 20-30 parts of glycidyl methacrylate.
7. The high-strength crack-resistant concrete according to claim 2, characterized in that: The aminated polyacrylonitrile fiber raw material comprises the following components: 100-120 parts by weight of epoxidized polyacrylonitrile fiber and 300-350 parts by weight of hydrazine hydrate aqueous solution.
8. The high-strength crack-resistant concrete according to claim 2, characterized in that: The modified polyacrylonitrile fiber raw material comprises the following components: by weight, 100-120 parts of aminated polyacrylonitrile fiber, 30-50 parts of phosphoric acid, 10-20 parts of urea, and 400-450 parts of water.
9. A process for preparing high-strength crack-resistant concrete according to any one of claims 1 to 8, characterized in that: The process includes the following: cement, river sand and gravel are put into a mixer, dry-mixed until uniform, then polycarboxylate water reducer and deionized water are slowly added, wet-mixed, and then the composite reinforcing agent is added to the mixer in batches, and stirring is continued for 3-5 minutes. After curing, high-strength crack-resistant concrete is obtained.
10. The process for preparing high-strength crack-resistant concrete according to claim 9, characterized in that: The dry mixing time is 2-3 minutes; the wet mixing time is 1-2 minutes.