Mass concrete for water-saving ship lock and preparation method of mass concrete

Abstract

The invention discloses mass concrete for a water-saving ship lock and a preparation method of the mass concrete. The mass concrete for the water-saving ship lock is prepared from the following raw materials: 252 to 282 parts of moderate-heat anti-cracking cement, 100 to 118 parts of anti-cracking admixture, 235 to 255 parts of phase change sand, 180 to 200 parts of natural sand, 980 to 1020 parts of coarse aggregate, 155 to 170 parts of water and 5 to 7 parts of water reducing agent. The moderate-heat anti-cracking cement is used for replacing ordinary Portland cement, the anti-cracking admixture is used for replacing conventional admixtures such as coal ash mineral powder, and the phase change sand is used for replacing part of natural sand as fine aggregate, so that hydration temperature rise and temperature drop stress of the mass concrete are effectively inhibited; the straw fiber is modified by the modifier, the capability of cellulose and lignin in the straw fiber in participating in cement hydration reaction is excited, the binding power of the fiber and a concrete matrix interface transition area is improved, and waste associated with agricultural products such as straw and chaff can be utilized with high value while the anti-cracking capability of the concrete is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete for shipping hub projects, and more specifically, the present invention relates to large-volume concrete for water-saving ship locks and a preparation method thereof. Background Art

[0002] As a new type of structure on inland waterways that is economical, convenient, and meets ecological needs, water-saving ship locks can significantly improve water conservation efficiency and effectively utilize water resources by building water tanks on one or both sides of the lock chamber to temporarily store some of the water released when the lock chamber is discharged. The stored water is then pumped back into the lock chamber when the lock chamber is filled, saving water consumption during passage through the lock. The Pinglu Canal is located in a hot and high-temperature environment. Its shipping hub project faces problems such as high pouring temperatures for large-volume concrete in hot environments, complex structural design of water-saving ship locks, and large areas of strong constraint areas. Conventional water pipe cooling and surface insulation measures to suppress shrinkage cracking have reached a bottleneck, resulting in a high risk of cracking in the large-volume concrete of the shipping hub hydraulic structure.

[0003] However, compared with the large-volume concrete of traditional dam hydraulic structures, the large-volume concrete structure in the Pinglu Canal hub project is more complex, the concrete grade is higher, and the risk of cracking is greater. It is urgent to carry out research on the preparation technology of high-crack-resistant large-volume concrete for water-saving ship locks in the Pinglu Canal shipping hub project.

[0004] To address the above issues, the traditional method is to use admixtures to control concrete properties. The addition of expansive agents can improve the shrinkage stress of large-volume concrete. However, the addition of traditional expansive agents mainly compensates for the drying shrinkage and autogenous shrinkage of large-volume concrete, and has limited effect on compensating for the temperature shrinkage of large-volume concrete. In addition, there are related patents that use paraffin as a phase change material to solve the problem of controlling the hydration temperature rise of concrete. However, paraffin is prone to leakage after the phase change, making it more difficult to control the temperature rise of concrete, requiring the use of special packaging measures. There are also related patents that can improve the crack resistance of concrete by adding organic polymer fibers. However, due to the lack of chemical reaction ability between the fiber surface and cement, a clear interface transition zone exists between the fiber and the concrete matrix.

[0005] The Pinglu Canal navigation hub features complex structural designs for key components such as the central pier, chamber walls, water transfer corridors, and upper and lower gates. These components, along with extensive areas of strong restraint, pose a significant risk of cracking in hot weather. Therefore, the massive concrete used as the primary component of the locks must not only meet basic performance requirements such as strength but also exhibit excellent crack resistance and durability. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention provides a mass concrete for water-saving ship locks and a method for its preparation. By optimizing raw materials and their composition, a mass concrete for water-saving ship locks is produced. Compared to conventional hydraulic mass concrete, the mass concrete produced using this method exhibits a lower hydration temperature rise and higher crack resistance, helping to extend the service life of typical structural components of water-saving ship locks, such as the center piers, chamber walls, water transfer corridors, and upper and lower gate heads.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention to solve the technical problem is as follows: A large-volume concrete for a water-saving ship lock comprises the following raw materials, measured by mass: 252-282 parts of medium-heat crack-resistant cement, 100-118 parts of crack-resistant admixture, 235-255 parts of phase-change sand, 180-200 parts of natural sand, 980-1020 parts of coarse aggregate, 155-170 parts of water, and 5-7 parts of water reducer.

[0008] The medium-heat anti-cracking cement is prepared by mixing medium-heat Portland cement clinker particles, gypsum and light-burned MgO through high-speed grinding in a ball mill; and the mass ratio of the medium-heat Portland cement clinker particles, gypsum and light-burned MgO is (70-95): (2-8): (3-12).

[0009] The gypsum is one of dihydrate gypsum, anhydrite or abrasive gypsum associated with the production of ceramic products, or a mixture of the two in any proportion.

[0010] The light-burned MgO is a high-activity MgO particle with a hydration activity of about 100s-120s.

[0011] The anti-cracking admixture is prepared by the following method: fly ash, ion-doped modified calcium expansion material and calcined gypsum are mixed and compounded; the mass ratio of the fly ash, ion-doped modified calcium expansion material and calcined gypsum is (60-80): (10-30): (5-20).

[0012] The light-burned MgO is obtained by calcining in a suspension kiln, ensuring that the hydration activity of the light-burned MgO is higher than 100s The mixing and compounding is carried out by a single-shaft plowshare type forced mixer, which has the functions of breaking up and forcing super-dispersion, thereby improving the mixing uniformity of the three components of fly ash, calcium expansive material and calcined gypsum.

[0013] The ion-doped modified calcium expansion material is a calcium expansion material that is doped with 0.5%-1.0% boron ions during the calcination preparation process for doping modification, which inhibits the early expansion development rate of the calcium expansion material and improves the expansion efficiency of the calcium expansion material in the middle and late stages.

[0014] The calcium expansion material is an expansion clinker with calcium oxide as the expansion source, also known as calcium oxide expansion clinker.

[0015] The boron ions are derived from borosilicate, borate and boron oxide minerals.

[0016] The calcined gypsum is free gypsum prepared by calcining gypsum powder at a temperature of 450° C. to 550° C. for 20 to 30 minutes.

[0017] The phase change sand is prepared by the following method: ceramic sand is placed in an emulsified paraffin solution and soaked for 1-2 hours to ensure that the emulsified paraffin can fully penetrate the inner pores of the ceramic sand, and after leaching, it is transferred to a drying chamber and dried in an inert gas protective atmosphere to obtain phase change sand with temperature phase change function composed of porous ceramic particles and paraffin hidden in the porous ceramic particles.

[0018] The solvent of the emulsified paraffin solution is a nonionic emulsifier selected from paraffin-specific emulsifier KC-06 and No. 58 paraffin-specific emulsifier.

[0019] The natural sand is natural river sand with a fineness modulus of 2.5-2.6.

[0020] The coarse aggregate is granite crushed stone with a low thermal expansion coefficient and a particle size between 10-30 mm.

[0021] The water reducer is a polyether water reducer.

[0022] Furthermore, the large-volume concrete for the water-saving ship lock further comprises 30-40 parts by mass of porous powdered quartz; the porous powdered quartz has a mesh size of 350-500 meshes.

[0023] Furthermore, the large-volume concrete for the water-saving ship lock further comprises 15-18 parts by mass of floating beads.

[0024] Furthermore, the large-volume concrete for the water-saving ship lock further comprises 9-15 parts by mass of modified straw fiber.

[0025] The modified straw fiber is prepared by the following method: waste associated with agricultural products such as corn, cotton, soybean, rice, wheat straw and husk is crushed into flocs using a particle crusher, immersed in a straw modifier composite solution with a mass fraction of 2%-4% for 20-30 minutes, drained and shade-dried, and then shaped into filaments, and then sheared and air-dried to obtain the modified straw fiber.

[0026] The straw modifier is selected from boric acid glycerol, boric acid glycol ester, γ-aminopropyl triethoxysilane Straw is the general term for the stems and leaves of mature crops. Its crude fiber content is as high as 30%-40%, and it is rich in cellulose and lignin. It has the ability to participate in hydration reactions in a cement-based alkaline environment, and can therefore be used in the production and preparation of cement-based materials.

[0027] The method for preparing large-volume concrete for a water-saving ship lock comprises the following steps: (1) Prepare medium heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand and coarse aggregate according to mass; ⑵. Add the corresponding amount of water reducer to the corresponding amount of water and stir to form a uniformly dispersed mixed solution; ⑶. Stir the corresponding amounts of medium-heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand, and coarse aggregate in a mixer at low speed for 60-90 seconds, then add 80%-85% of the mixed solution, stir at low speed for 120-150 seconds, and finally add the remaining mixed solution and stir at high speed for 90-120 seconds to obtain fresh concrete.

[0028] Furthermore, in the step (3), porous powdered quartz and floating beads are added during the initial low-speed stirring.

[0029] Furthermore, in step (3), the modified straw fiber is added during the final low-speed stirring.

[0030] Furthermore, in step (1), the preparation method of the medium-heat anti-cracking cement is: the medium-heat silicate cement clinker particles, gypsum particles with a particle size of 5-15 mm and light-burned MgO particles with a particle size of 0.1-1 mm are fed into a ball mill after being measured by a metering belt scale, and successively enter the first bin of the ball mill for coarse grinding, the second bin for medium grinding, and the third bin for fine grinding. After graded powder grinding and mixing, the powder is selected by a powder classifier to obtain the medium-heat anti-cracking cement.

[0031] Furthermore, in step (1), the preparation method of the anti-cracking admixture is: fly ash with a fineness of 350 mesh-400 mesh, ion-doped modified calcium expansive material with a fineness of 150 mesh-200 mesh, and calcined gypsum with a fineness of 250 mesh-300 mesh are automatically measured on a weighing scale and then stirred at high speed for 150-180s in a single-axis plowshare forced mixer to mix evenly to obtain the anti-cracking admixture.

[0032] Furthermore, in step (1), the preparation process of the phase change sand is to evenly place the ceramic granular sand into the emulsified paraffin solution, and slowly stir and turn the ceramic granular sand with a stirring blade during the process so that the emulsified paraffin can more fully penetrate into the inner pores of the ceramic granular sand. After soaking for 1-2 hours, it is drained out and transferred to a drying chamber. Inert gas is introduced into the drying chamber, and the phase change sand with temperature phase change function composed of porous ceramic particles and paraffin hidden in the porous ceramic particles is dried in an inert gas protective atmosphere.

[0033] Furthermore, in step (1), the preparation process of the modified straw fiber is as follows: the collected waste associated with agricultural products such as corn, cotton, soybean, rice, wheat straw and husk is crushed into flocs using a particle crusher, and then the flocs are placed in a straw modifier alcohol composite solution with a mass fraction of 2%-4% and soaked for 20-30 minutes. During the soaking process, the flocs are slowly stirred to make the flocs more fully dispersed in the boric acid glycerol alcohol composite solution, drained and dried in the shade to remove the residual liquid in the flocs, and then the flocs are shaped into filamentous straw using a shaping machine, and then sheared and air-dried to obtain modified straw fibers.

[0034] The present invention adopts medium-heat crack-resistant cement to replace ordinary Portland cement, which can reduce the hydration heat of cement itself and effectively compensate for the temperature drop and shrinkage of large-volume concrete by utilizing the temperature sensitivity characteristics of the hydration expansion of light-burned MgO; adopts anti-cracking admixture to replace conventional admixtures such as fly ash and mineral powder, which can reduce the amount of cement in large-volume concrete and control the overall hydration heat of cementitious materials, and effectively compensate for the hydration shrinkage of large-volume concrete by utilizing the ion-doped modified calcium expansive material and the expansion characteristics of free gypsum; adopts phase-change sand to replace part of natural sand as fine aggregate, which can effectively suppress the hydration temperature rise of large-volume concrete by utilizing the temperature phase change characteristics of paraffin stored in the inner pores of the phase-change sand while ensuring the hardness of the fine aggregate particles. By rationally using porous powdered quartz and floating beads, the mechanical properties of concrete are improved while suppressing its own shrinkage; by soaking modified straw fibers in boric acid glycerol, the ability of cellulose and lignin in the straw fibers to participate in cement hydration reactions is stimulated, improving the bonding strength of the transition zone between the fiber and concrete matrix interface. While improving the crack resistance of concrete, waste associated with agricultural products such as straw and husks can be utilized at high value.

[0035] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. Straw and husk are waste products generated during the agricultural grain production process. Due to environmental protection control, they cannot be burned on site to make organic fertilizer and return to farmland. They pile up into mountains every harvest season. However, since they contain a large amount of cellulose and lignin, they can participate in the hydration reaction of cement and adhere to the hydrated gel under the conditions of soaking and modification with straw modifiers, thereby strengthening the interface transition zone between the fiber and the concrete matrix, thereby improving the crack resistance and mechanical properties of the concrete.

[0036] 2. The present invention utilizes the liquid state of emulsified paraffin at room temperature and immerses porous ceramic sand in it to prepare phase-change sand with temperature phase-change characteristics. The phase-change sand can absorb hydration heat and convert into liquid during the heating process of large-volume concrete. When the large-volume concrete is in the cooling process, the paraffin solidifies and releases heat, thereby reducing the temperature drop amplitude and temperature drop stress of the large-volume concrete, and correspondingly reducing the cracks in the large-volume concrete caused by temperature stress.

[0037] 3. The medium-heat anti-cracking cement used in the present invention is prepared by grinding and mixing three groups of raw materials, namely medium-heat cement clinker, gypsum and light-burned MgO, in proportion in advance. The anti-cracking admixture used is prepared by compounding and mixing fly ash, ion-doped modified calcium expansive material and calcined gypsum in advance. By promoting and homogenizing the mixing of the medium-heat anti-cracking cement and the anti-cracking admixture, the dispersion uniformity of the two core raw materials, cement and admixture, is improved, which is beneficial to improving the shrinkage stress of large-volume concrete and improving the anti-cracking performance of concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The test temperature change curve simulates the actual temperature change process of large-volume concrete of a certain water-saving ship lock during the 90-day period.

[0039] Figure 2 The autogenous volume deformation curves of the mass concrete prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 under variable temperature curing conditions are shown. DETAILED DESCRIPTION

[0040] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0041] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0042] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0043] The medium-heat anti-cracking cement is prepared by mixing 90% medium-heat silicate cement clinker particles, 4% gypsum and 6% light-burned MgO through high-speed grinding in a ball mill; the anti-cracking admixture is prepared by mixing and compounding 70% fly ash, 20% ion-doped modified calcium expansive material and 10% calcined gypsum through a single-shaft plowshare forced mixer.

[0044] The phase change sand is ceramic sand that is soaked in an emulsified paraffin solution for 1-2 hours, and then dried in an inert gas protective atmosphere after leaching to obtain phase change sand with temperature phase change function composed of porous ceramic particles and paraffin hidden in the porous ceramic particles; the modified straw fiber is waste associated with agricultural products such as corn, cotton, soybean, rice, wheat straw and husk, which is crushed into flocs by a particle crusher, soaked in a boric acid glycerol composite solution with a mass fraction of 2%-4% for 20-30 minutes, drained, dried in the shade, shaped, sheared and air-dried to obtain the modified straw fiber.

[0045] The method for preparing the mass concrete of the water-saving ship lock obtained in the following embodiment adopts the following steps: ⑴. Prepare the following raw materials by mass: medium heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand, coarse aggregate, water, and water reducer; ⑵. Add the corresponding amount of water reducer to the corresponding amount of water and stir to form a uniformly dispersed mixed solution; ⑶. Stir the corresponding amounts of medium-heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand, and coarse aggregate in a mixer at low speed for 60-90 seconds, then add 80%-85% of the mixed solution, stir at low speed for 120-150 seconds, and finally add the remaining mixed solution and stir at high speed for 90-120 seconds to obtain fresh concrete.

[0046] The preparation method of the medium-heat crack-resistant cement is as follows: 90% of medium-heat Portland cement clinker particles, 4% of gypsum particles with a particle size of 5-15 mm, and 6% of light-burned MgO particles with a particle size of 0.1-1 mm are fed into a ball mill after being measured by a metering belt scale, and successively enter the first bin of the ball mill for coarse grinding, the second bin for medium grinding, and the third bin for fine grinding. After graded powder grinding and mixing, the powder is selected by a powder classifier to obtain the medium-heat crack-resistant cement.

[0047] The preparation method of the anti-cracking admixture is as follows: 70% of fly ash with a fineness of 350 mesh to 400 mesh, 20% of ion-doped modified calcium expansive material with a fineness of 150 mesh to 200 mesh, and 10% of calcined gypsum with a fineness of 250 mesh to 300 mesh are automatically measured on a weighing scale, and then stirred at high speed for 150 to 180 seconds in a single-shaft plowshare forced mixer to uniformly mix to obtain the anti-cracking admixture.

[0048] The preparation process of the phase change sand is as follows: paraffin wax and an emulsifier are emulsified into a paraffin solution at a temperature of 40-50°C, ceramic granular sand is evenly placed into the emulsified paraffin solution, and the ceramic granular sand is slowly stirred and turned with a stirring blade during the process so that the emulsified paraffin can more fully penetrate into the inner pores of the ceramic granular sand. After soaking for 1-2 hours, the sand is drained out and transferred to a drying chamber, nitrogen is introduced into the drying chamber, and the sand is dried in an inert gas protective atmosphere to obtain phase change sand with temperature phase change function composed of porous ceramic particles and paraffin wax hidden in the porous ceramic particles.

[0049] The preparation process of the modified straw fiber is as follows: collected waste associated with agricultural products such as corn, cotton, soybean, rice, and wheat straw and husks are crushed into flocs using a particle crusher, and then the flocs are placed in a straw modifier composite solution with a mass fraction of 2% to 4% and soaked for 20 to 30 minutes. During the soaking process, the flocs are slowly stirred to make the flocs more fully dispersed in the boric acid glycerol composite solution. The flocs are drained and dried in the shade to remove the residual liquid in the flocs. The flocs are then shaped into filamentous straw using a shaping machine, and sheared and air-dried to obtain modified straw fibers. In the following embodiments, the straw modifiers are selected from boric acid glycerol, boric acid ethylene glycol ester, γ-aminopropyl triethoxysilane, boric acid glycerol, and boric acid ethylene glycol ester to soak the modified straw. Example

[0050] 282 parts of medium-heat anti-cracking cement, 118 parts of anti-cracking admixture, 235 parts of phase change sand, 180 parts of natural sand, 980 parts of coarse aggregate, 40 parts of porous powder quartz, 18 parts of floating beads, 15 parts of modified straw fiber, 155 parts of water, and 7 parts of water reducer. Example

[0051] 266 parts of medium-heat anti-cracking cement, 110 parts of anti-cracking admixture, 245 parts of phase change sand, 190 parts of natural sand, 1000 parts of coarse aggregate, 35 parts of porous powder quartz, 17 parts of floating beads, 12 parts of modified straw fiber, 163 parts of water, and 6 parts of water reducer. Example

[0052] 252 parts of medium-heat anti-cracking cement, 100 parts of anti-cracking admixture, 255 parts of phase change sand, 200 parts of natural sand, 1020 parts of coarse aggregate, 30 parts of porous powder quartz, 15 parts of floating beads, 9 parts of modified straw fiber, 170 parts of water, and 7 parts of water reducer. Example

[0053] 282 parts of medium-heat anti-cracking cement, 100 parts of anti-cracking admixture, 255 parts of phase change sand, 200 parts of natural sand, 1020 parts of coarse aggregate, 15 parts of floating beads, 9 parts of modified straw fiber, 170 parts of water, and 7 parts of water reducer. Example

[0054] 252 parts of medium-heat anti-cracking cement, 115 parts of anti-cracking admixture, 255 parts of phase change sand, 200 parts of natural sand, 1020 parts of coarse aggregate, 30 parts of porous powder quartz, 9 parts of modified straw fiber, 170 parts of water, and 7 parts of water reducer. Example

[0055] 252 parts of medium-heat anti-cracking cement, 109 parts of anti-cracking admixture, 255 parts of phase change sand, 200 parts of natural sand, 1020 parts of coarse aggregate, 30 parts of porous powder quartz, 15 parts of floating beads, 170 parts of water, and 7 parts of water reducer.

[0056] Two comparative experiments were conducted, Comparative Example 1 and Comparative Example 2, to compare the mechanical properties, crack resistance, and thermal insulation performance of the mass concrete of the present invention and the traditional mass concrete. The specific formulations are as follows: Comparative Example 1 266 parts of 42.5 grade ordinary Portland cement, 110 parts of fly ash, 435 parts of natural sand, 1000 parts of coarse aggregate, 52 parts of mineral powder, 12 parts of polypropylene fiber, 163 parts of water, and 6 parts of water reducer.

[0057] Comparative Example 2 266 parts of 42.5 grade medium-heat Portland cement, 110 parts of fly ash, 435 parts of artificial sand, 1000 parts of coarse aggregate, 64 parts of mineral powder, 163 parts of water, and 6 parts of water reducer.

[0058] The concrete mechanical properties test methods were conducted in accordance with GB / T 50081-2019, "Standard for Test Methods for Physical and Mechanical Properties of Concrete." The concrete adiabatic temperature rise test method was conducted in accordance with GB / T 50080-2016, "Standard for Test Methods for Performance of Ordinary Concrete Mixtures." The early-stage crack resistance of concrete was tested in accordance with GB / T 50082-2024, "Standard for Test Methods for Long-term Properties and Durability of Ordinary Concrete." The specific experimental results are shown in Tables 1, 2, and 3.

[0059] Table 1 shows the test results of concrete compressive strength and splitting tensile strength (MPa)

[0060] Table 2 shows the results of the concrete adiabatic temperature rise test (℃)

[0061] Table 3 shows the experimental results of early crack resistance of concrete

[0062] The existing standards for evaluating the shrinkage performance of concrete are all carried out under standard curing conditions of 20°C, but in actual concrete structures, the heat released by cement hydration or changes in the external environment cause the temperature of the concrete to change over time. In order to evaluate the application effect of the present invention in actual projects, the actual temperature change history of a certain section of large-volume concrete of a water-saving ship lock during the 90d age period was taken as the test temperature curve, and the development history of the spontaneous volume deformation of the embodiments of the present invention and the comparative examples under a variable temperature curing environment was compared and evaluated. The fresh concrete obtained from Example 1, Example 2, Example 3, Example 4, Example 5, Example 6 and Comparative Examples 1 and 2 of the present invention was cast into a concrete cylinder of φ150×500mm, a strain gauge was buried in the specimen, and it was sealed and cured in an environmental test box. The test temperature change curve in the environmental test box is shown in FIG. Figure 1 The test results of the concrete autogenous volume deformation during temperature-variable curing are shown in Table 1. Figure 2 .

[0063] As shown in Table 1, combined with Comparative Example 1 and Comparative Example 2, it can be concluded that compared with ordinary Portland cement and medium-heat Portland cement, the early compressive strength and splitting strength of the mass concrete prepared with crack-resistant medium-heat cement, crack-resistant admixture, porous powder quartz and floating beads are relatively low, but the later compressive strength, splitting strength and strength increase are significantly higher than those of the comparative examples, indicating that the mass concrete prepared by this method has better mechanical properties.

[0064] Examples 4 to 6 each lack porous powdered quartz, floating beads and straw fibers. Their 28d compressive strength and splitting tensile strength are both lower than those of Examples 1 to 3 with all components. However, the 28d splitting tensile strength of Examples 4 to 6 are better than those of Comparative Examples 1 and 2, indicating that the mechanical properties of the examples formulated with all components are superior.

[0065] As shown in Table 2, combined with Comparative Example 1 and Comparative Example 2, it can be concluded that compared with ordinary Portland cement and medium-heat Portland cement, the early adiabatic temperature rise of the mass concrete prepared with anti-cracking medium-heat cement + anti-cracking admixture + phase change sand before 3 days is significantly lower than that of the comparative example, and the adiabatic temperature rise at 7 days is also lower than the corresponding value of the comparative example, indicating that the adoption of this method can significantly reduce the adiabatic temperature rise of the mass concrete, correspondingly reduce the temperature drop amplitude and temperature drop shrinkage stress of the mass concrete, and improve the crack resistance of the mass concrete.

[0066] The thermal insulation temperature rise performance of Examples 4 to 6 is comparable to that of Examples 1 to 3 with all components, and is superior to Comparative Examples 1 and 2, indicating that the presence or absence of components such as porous powdered quartz, floating beads and straw fiber has no significant effect on the thermal insulation temperature rise of concrete.

[0067] As shown in Table 3, combined with Comparative Examples 1 and 2, it can be concluded that compared with ordinary Portland cement and medium-heat Portland cement, large-volume concrete prepared with anti-cracking medium-heat cement + anti-cracking admixture + modified straw fiber can effectively reduce the occurrence of early cracks and even eliminate the risk of early cracking. Even if early cracks occur, the crack width, crack length and crack area are significantly suppressed.

[0068] The early crack resistance of Examples 4 to 6 is lower than that of Examples 1 to 3 with full components, but is better than that of Comparative Examples 1 and 2, indicating that the examples formulated with full components have better crack resistance.

[0069] like Figure 2As shown, the large-volume concretes all produce obvious autogenous volume expansion deformation with the increase of temperature, and autogenous volume shrinkage deformation with the decrease of temperature. Compared with the large-volume concretes formulated with ordinary Portland cement and medium-heat Portland cement, which show obvious temperature rise and temperature drop deformation in a variable temperature environment, the large-volume concrete formulated with anti-cracking medium-heat cement + anti-cracking admixtures shows greater autogenous volume expansion deformation in the temperature rise stage, and smaller autogenous volume shrinkage deformation in the temperature drop stage. The autogenous volume deformation performance of Examples 4 to 6 is slightly lower than that of Examples 1 to 3 with all components, but they are all better than Comparative Examples 1 and 2, indicating that the examples formulated with all components have better autogenous volume deformation performance and better anti-cracking effect.

[0070] The autogenous volume deformation of the traditional large-volume concrete prepared in the comparative example is greatly affected by temperature rise and temperature drop, while the autogenous volume deformation of the large-volume concrete prepared in the embodiment of the present invention is less affected by temperature rise and temperature drop, the corresponding temperature drop shrinkage tensile stress is smaller, and the overall crack resistance of the concrete is significantly improved.

[0071] The above results show that the present invention effectively suppresses the hydration temperature rise and temperature drop shrinkage stress of large-volume concrete by replacing ordinary Portland cement with medium-heat crack-resistant cement, replacing conventional admixtures such as fly ash powder with crack-resistant admixtures, and replacing part of natural sand as fine aggregate with phase change sand; by rationally using porous powdered quartz and floating beads, the mechanical properties of concrete are improved while suppressing the self-shrinkage of concrete; by soaking modified straw fibers with boric acid glycerol, the ability of cellulose and lignin in straw fibers to participate in cement hydration reactions is stimulated, improving the bonding strength of the transition zone between the fiber and concrete matrix interface, while improving the crack resistance of concrete, it can make high-value use of waste associated with agricultural products such as straw and husks. The large-volume concrete prepared by the embodiment of the present invention has better results in mechanical properties, adiabatic temperature rise, early crack resistance, and autogenous volume deformation performance under variable temperature conditions than the traditional large-volume concrete prepared in the comparative example, which fully demonstrates the reliability of the present invention.

[0072] The embodiments of this specification are merely examples of implementations of the invention and are provided for illustrative purposes only. The scope of protection of the present invention should not be considered limited to the specific embodiments described in these embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by a person of ordinary skill in the art based on the invention.

Claims

1. A large volume concrete for water-saving ship lock, characterized in that: The raw materials include the following by mass: 252-282 parts of medium heat anti-cracking cement, 100-118 parts of anti-cracking admixture, 235-255 parts of phase change sand, 180-200 parts of natural sand, 980-1020 parts of coarse aggregate, 155-170 parts of water, and 5-7 parts of water reducer; The medium-heat anti-cracking cement is prepared by mixing medium-heat Portland cement clinker particles, gypsum, and light-burned MgO through high-speed grinding in a ball mill; and the mass ratio of the medium-heat Portland cement clinker particles, gypsum, and light-burned MgO is (70-95): (2-8): (3-12); The gypsum is one or a mixture of dihydrate gypsum, anhydrite or abrasive gypsum associated with the production of ceramic products in any proportion; The light-burned MgO is a high-activity MgO particle with a hydration activity of about 100s-120s; The anti-cracking admixture is prepared by the following method: fly ash, ion-doped modified calcium expansive material and calcined gypsum are mixed and compounded; the mass ratio of the fly ash, ion-doped modified calcium expansive material and calcined gypsum is (60-80): (10-30): (5-20); The ion-doped modified calcium expansion material is a calcium expansion material that is doped with 0.5%-1.0% boron ions during the calcination preparation process for doping modification; the boron ions are derived from borosilicate, borate, and boron oxide minerals; The phase change sand is prepared by the following method: placing ceramic sand into an emulsified paraffin solution and soaking it for 1-2 hours, leaching it out and transferring it to a drying chamber, and drying it in an inert gas protective atmosphere to obtain a phase change sand with temperature phase change function composed of porous ceramic particles and paraffin embedded in the porous ceramic particles; The natural sand is natural river sand with a fineness modulus of 2.5-2.6; The coarse aggregate is granite crushed stone with low thermal expansion coefficient and particle size is between 10-30mm; The water reducer is a polyether water reducer.

2. The large-volume concrete for water-saving ship lock according to claim 1, characterized in that: The calcareous expansion material is calcium oxide expansion clinker.

3. The large-volume concrete for water-saving ship lock according to claim 1, characterized in that: The light-burned MgO is obtained by calcining in a suspension kiln.

4. The large-volume concrete for water-saving ship lock according to claim 1, characterized in that: The mixing and compounding is carried out by a single-shaft plowshare type forced mixer.

5. The large-volume concrete for water-saving shiplock according to claim 1, characterized in that: The calcined gypsum is free gypsum prepared by calcining gypsum powder at a temperature of 450° C. to 550° C. for 20 to 30 minutes.

6. The large-volume concrete for water-saving ship lock according to claim 1, characterized in that: The solvent of the emulsified paraffin solution is a nonionic emulsifier selected from paraffin-specific emulsifier KC-06 and No. 58 paraffin-specific emulsifier.

7. The large volume concrete for water-saving ship lock according to claim 1, characterized in that: The large-volume concrete for the water-saving ship lock further comprises 30-40 parts by mass of porous powdered quartz; the porous powdered quartz has a mesh size of 350-500 meshes; Preferably, the large-volume concrete for water-saving ship lock further comprises 15-18 parts by mass of floating beads; Preferably, the large-volume concrete for water-saving ship lock further comprises 9-15 parts by mass of modified straw fiber.

8. The large-volume concrete for water-saving shiplock according to claim 7, characterized in that: The modified straw fiber is prepared by the following method: waste associated with agricultural products such as corn, cotton, soybean, rice, wheat straw and husk is crushed into flocs using a particle crusher, immersed in a boric acid glycerol composite solution with a mass fraction of 2%-4% for 20-30 minutes, drained and shade-dried, and then shaped into filaments, and then sheared and air-dried to obtain the modified straw fiber.

9. The method for preparing the mass concrete for water-saving shiplock according to any one of claims 1 to 8, comprising the following steps: (1) Prepare medium heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand and coarse aggregate according to mass; ⑵. Add the corresponding amount of water reducer to the corresponding amount of water and stir to form a uniformly dispersed mixed solution; ⑶. Stir the corresponding amounts of medium-heat anti-cracking cement, anti-cracking admixture, phase change sand, natural sand, and coarse aggregate in a mixer at low speed for 60-90 seconds, then add 80%-85% of the mixed solution, stir at low speed for 120-150 seconds, and finally add the remaining mixed solution and stir at high speed for 90-120 seconds to obtain fresh concrete.

10. The method according to claim 9, characterized in that: In the step (3), porous powdered quartz, floating beads and modified straw fibers are added during initial low-speed stirring; Preferably, the modified straw fiber is prepared by: collecting waste associated with agricultural products such as corn, cotton, soybean, rice, and wheat straw and husks using a particle crusher to crush the waste into flocculent form, then soaking the flocculent form in a straw modifier composite solution with a mass fraction of 2% to 4% for 20 to 30 minutes, slowly stirring the flocculent form during the soaking process to allow the flocculent straw to be more fully dispersed in the boric acid glycerol composite solution, draining and drying in the shade to remove residual liquid in the flocculent straw, and then shaping the flocculent straw into filamentous straw using a shaping machine, shearing, and air-drying to obtain the modified straw fiber; The straw modifier is selected from boric acid glycerol, boric acid ethylene glycol ester, and γ-aminopropyltriethoxysilane.

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