Process for the preparation of a concrete with excellent frost resistance

Abstract

The application discloses a preparation process of concrete with excellent anti-freezing performance, which comprises the following steps: weighing raw materials according to weight parts, namely, 330-350 parts of cement, 650-700 parts of fine aggregate, 850-900 parts of coarse aggregate, 80-100 parts of fly ash, 20-40 parts of silica ash, 3-8 parts of water reducing agent, 20-35 parts of composite fiber material, 5-10 parts of anti-freezing agent and 160-180 parts of water; mixing the fine aggregate and the coarse aggregate uniformly to obtain an aggregate mixture; adding the composite fiber into the aggregate mixture, mixing uniformly, adding the cement, the fly ash and the silica ash, and mixing uniformly to obtain a premix; mixing the water reducing agent and the anti-freezing agent in water uniformly to obtain an additional liquid; adding the additional liquid into the premix, stirring uniformly, and the concrete with excellent anti-freezing performance is obtained. The concrete with excellent anti-freezing performance is particularly suitable for infrastructure construction in cold regions, can effectively reduce the damage of freeze-thaw cycles to structures, and prolongs the service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a preparation process of concrete with excellent anti-freezing performance. BACKGROUND

[0002] As an important material widely used in construction and infrastructure engineering, the anti-freezing performance of concrete has always been an important factor affecting its long-term durability and safety. Especially in cold regions, concrete exposed to low temperature environment is prone to frost heaving, cracking, strength reduction and other problems, which seriously affects the stability and service life of the structure. Therefore, improving the anti-freezing performance of concrete is an important topic in the research and application of concrete.

[0003] In order to cope with the performance challenges of concrete in cold environment, a series of technical means have been taken in the industry to improve the anti-freezing performance of concrete. These means mainly include: 1. Adding anti-freezing agent: Anti-freezing agent is a kind of chemical substance that can reduce the freezing point of water in concrete. By adding anti-freezing agent, the fluidity of concrete can still be maintained at a lower temperature, reducing the internal stress caused by ice. 2. Improving the mix proportion of concrete: By optimizing the mix proportion of concrete, such as increasing the amount of cement, using low water-cement ratio, or by adding mineral admixtures (such as fly ash, silica fume, etc.), the density and strength of concrete can be improved, thereby enhancing its anti-freezing performance. 3. Introducing fiber reinforced materials: Adding fiber reinforced materials, such as basalt fiber, etc., to concrete can improve the toughness and crack resistance of concrete, reducing the cracks caused by freeze-thaw cycles. 4. Using high-performance admixtures: High-performance admixtures, such as polycarboxylate superplasticizer, retarder, etc., can improve the workability and physical and mechanical properties of concrete, further improving its anti-freezing performance.

[0004] Although there are currently various methods to improve the anti-freezing performance of concrete, there are still some technical bottlenecks. For example, existing anti-freezing concrete mostly relies on the addition of anti-freezing agent, which will cause certain pressure on the environment and may affect other properties of concrete. In addition, the improvement effect of existing admixtures and fiber materials on anti-freezing performance is limited under some extreme low temperature conditions. Therefore, developing a new concrete preparation process with excellent anti-freezing performance is still a research hotspot and challenge in the field of concrete materials. SUMMARY

[0005] Based on the problems in the background art, the present application provides a concrete with excellent anti-freezing performance when used in cold regions, thereby improving its stability and service life in low temperature environment and meeting the engineering needs under different climate conditions.

[0006] The present application is implemented by the following technical solutions:

[0007] A preparation process of concrete with excellent anti-freezing performance, comprising the following steps:

[0008] S1. Measuring raw materials by weight parts, including cement 330-350 parts, fine aggregate 650-700 parts, coarse aggregate 850-900 parts, fly ash 80-100 parts, silica fume 20-40 parts, water reducing agent 3-8 parts, composite fiber material 20-35 parts, anti-freezing agent 5-10 parts and water 160-180 parts;

[0009] S2. Mixing the fine aggregate and the coarse aggregate uniformly to obtain an aggregate mixture;

[0010] S3. Adding the composite fiber to the aggregate mixture and mixing uniformly, and then adding the cement, fly ash and silica fume and mixing uniformly to obtain a premix;

[0011] S4. Mixing the water reducing agent and the anti-freezing agent in water to obtain an additional liquid;

[0012] S5. Adding the additional liquid to the premix and stirring uniformly to obtain the concrete with excellent anti-freezing performance.

[0013] Further, the composite fiber material is obtained by mixing modified glass fiber, modified polypropylene fiber and modified steel fiber according to the mass ratio (2-5):(1-3):(5-10).

[0014] Further, the preparation steps of the modified glass fiber are as follows: 50-60 parts of glass fiber is immersed in 5% NaOH solution, heated to 60°C and stirred for 30 min for activation, and then washed with water to neutralization; 7-8 parts of glycidyl methacrylate and 1.5-2.0 parts of acrylic acid are dissolved in 250 parts of ethanol / water mixed solution, the pH of the solution is adjusted to 6-7, the activated glass fiber is placed in the mixed solution, heated to 65°C under nitrogen atmosphere, and the stirring is started, 2wt% ammonium persulfate solution and 0.5wt% ferrous sulfate solution are added dropwise, and the reaction is carried out for 2-3h, then the pre-modified glass fiber is washed with ethanol and water and vacuum dried; the dried pre-modified glass fiber is immersed in 2wt% KH550 silane coupling agent, treated at room temperature for 30-60 min, and dried after treatment to obtain the modified glass fiber.

[0015] The activity and grafting reaction on the surface of the glass fiber introduce polar groups on the surface, which can form stronger chemical bonds with the hydration products in the cement matrix, thereby improving the interfacial bonding force between the glass fiber and the matrix, reducing the interface shedding, effectively dispersing the stress caused by freeze-thaw cycles, and reducing the cracks and structural damage of the concrete.

[0016] Further, the preparation steps of the modified polypropylene fiber are specifically: placing the dried polypropylene resin in a closed double-shaft heating mixer, heating to 180℃ until the resin is completely melted, under nitrogen protection, adding lithium-based ionic liquid LiNTf2 and glycidyl methacrylate while stirring, uniformly mixing, then continuously adding dicumyl peroxide, continuously stirring and uniformly mixing to obtain a molten mixture; extruding and granulating the molten mixture through a screw extruder, drying to obtain modified polypropylene material; melt spinning the modified polypropylene material through a silk-like machine to obtain the modified polypropylene fiber.

[0017] Further, the mass ratio of the polypropylene resin, lithium-based ionic liquid LiNTf2, glycidyl methacrylate and dicumyl peroxide is 100:(2-3.5):(3-5):(0.1-0.3).

[0018] The co-action of the lithium-based ionic liquid and the glycidyl methacrylate enables the introduction of stronger polar groups on the surface of the polypropylene fiber, enhances the adhesion to the cement matrix, and thus improves the crack resistance, compressive strength and frost resistance of the concrete. Compared with surface treatment, the functional groups introduced on the polypropylene molecular chain by melt modification will not fall off or fail during use. At the same time, the introduction of the lithium-based ionic liquid not only promotes the modification reaction, but also forms stable polar microzones in the fiber, which have good stability in the strong alkaline environment of the concrete.

[0019] Further, the preparation steps of the modified steel fiber are specifically: cleaning and drying the steel fiber with ethanol; preparing an ethanol / water mixed solution containing silane coupling agent KH560, adjusting the pH to 4.0-5.5, soaking the dried steel fiber therein, stirring at 45-55℃ for 1-2h, and drying the steel fiber after soaking to obtain the modified steel fiber.

[0020] Through the treatment of the KH560 silane coupling agent, the surface of the steel fiber becomes more hydrophilic, can form stronger chemical bonds with the cement matrix, and increase the strength and toughness of the concrete, especially at stress concentration sites such as tension and shear. The stability of the steel fiber in the concrete is enhanced, and it is not easy to fall off or disperse unevenly due to freezing and thawing or other environmental factors, thereby prolonging the service life of the concrete and improving its durability.

[0021] Further, the antifreeze agent includes propylene glycol, silane coupling agent, nano silicon dioxide, calcium acetate and polyethylene glycol phosphate, and the mass ratio of propylene glycol, silane coupling agent, nano silicon dioxide, calcium acetate and polyethylene glycol phosphate is (4-5):(0.3-0.5):(0.4-0.6):(0.2-0.3):(0.2-0.4).

[0022] The propylene glycol and calcium acetate in the anti-freezing agent composition of the present application can effectively reduce the freezing point of water in concrete and prevent freeze-thaw damage. Nano-silicon dioxide can further reduce freeze-thaw damage by increasing the density of concrete and reducing water retention. The polyethylene glycol phosphate is a polymer with surface activity and wetting properties, which can reduce the surface tension of the concrete surface, making the cement matrix more evenly distributed during hydration, and forming a more uniform cement matrix. The synergistic effect of silane coupling agent and nano-silicon dioxide can effectively improve the crack resistance of concrete, reduce the generation of micro-cracks in freeze-thaw cycles, and improve the overall durability of concrete. Further, the cement is one or more of Portland cement, aluminate cement, and sulfoaluminate cement.

[0023] Further, the fine aggregate is a mixture of river sand and machine-made sand, and the weight ratio of river sand to machine-made sand is (2-3) : 1;

[0024] The fineness modulus of the river sand is 2.5-2.9, and the clay content is less than 1%;

[0025] The fineness modulus of the machine-made sand is 2.7-3.0, and the clay content is less than 1%;

[0026] The coarse aggregate is one or both of gravel or pebble, with a particle size range of 5-25mm, a crushing index less than 5%, and a needle flake particle content less than 8%.

[0027] Further, the fly ash is Grade I fly ash;

[0028] The silica fume has a specific surface area greater than 20000m 2 / kg;

[0029] The water reducing agent is a polycarboxylic acid high-performance water reducing agent.

[0030] Further, in steps S2, S3 and S5, a mixing device is used for stirring and mixing, which includes a mixing tank, a plurality of support rods are fixedly arranged at the lower end of the mixing tank, a driving motor is fixedly arranged at the upper end of the mixing tank, the lower side output end of the driving motor extends into the mixing tank, the lower side output end of the driving motor is fixedly connected with an arc-shaped rotating plate, a trapezoidal ring plate is fixedly arranged on the upper side inner wall of the mixing tank, the two ends of the arc-shaped rotating plate are rotatably connected with the trapezoidal ring plate, a rotating tube is arranged at the eccentric position of the arc-shaped rotating plate, a plurality of hollow tubes are fixedly arranged on the rotating tube, an arc-shaped plate is slidably arranged on the hollow tube, a plurality of extension rods are fixedly arranged on the arc-shaped plate, a moving rod is arranged in the rotating tube, a plurality of helical blades are fixedly arranged on the moving rod, and a mixing blade is fixedly arranged at the lower end of the moving rod; a feeding pipe is arranged through the upper surface of the mixing tank, and a discharge port is arranged at the lower end of the mixing tank.

[0031] Further, the arc-shaped rotating plate is provided as a hollow structure, a sliding groove is formed on the arc-shaped rotating plate, a moving block is slidably arranged in the sliding groove, a rotating pipe is rotatably arranged on the moving block, an arc-shaped rack is fixedly arranged on the moving block, the arc-shaped rack is slidably arranged in the arc-shaped rotating plate, a rotating motor is fixedly arranged on the front side of the arc-shaped rotating plate, the rear side output end of the rotating motor extends into the arc-shaped rotating plate, a gear one is fixedly connected to the rear side output end of the rotating motor, the gear one is in meshing connection with the arc-shaped rack, a gear ring is also fixedly arranged in the trapezoidal ring plate, and a gear two is fixedly arranged on the rotating pipe.

[0032] Further, a sliding block is fixedly arranged on the moving rod, the sliding block is in sliding connection with the inner wall of the rotating pipe, the moving rod extends out of the rotating pipe in a downward sliding manner, a spring one is fixedly arranged at the lower end of the sliding block, the spring one is sleeved on the moving rod, and the lower end of the spring one is fixedly connected to the lower side inner wall of the rotating pipe.

[0033] The beneficial effects of the present application are as follows:

[0034] 1. The anti-freezing agent of the concrete can effectively reduce the freezing point of the concrete, reduce the expansion and cracks caused by water freezing at low temperature, thereby significantly improving the frost resistance of the concrete, prolonging the service life of the concrete, especially in cold climate conditions. The addition of the composite fiber material not only increases the mechanical strength of the concrete, but also effectively prevents the formation of cracks caused by freeze-thaw cycles. The dispersion of the fiber helps to slow down the stress concentration and prevent the expansion of micro-cracks under the action of freeze-thaw, further enhancing the anti-cracking performance.

[0035] 2. The composite fibers in this invention include modified glass fibers, modified polypropylene fibers, and modified steel fibers. These three fibers form a multi-scale reinforcement system, enhancing concrete performance through comprehensive synergistic effects from the micro to the macro scale. Specifically, the modified glass fibers, with their small diameter and optimized interfacial bonding, control the initiation of early cracks at the microscale. The modified polypropylene fibers, through moderate plastic deformation, absorb crack propagation energy and alleviate internal stress at the mesoscale. The modified steel fibers, relying on their high strength and high modulus, provide primary structural reinforcement and crack bridging at the macroscale. This three-dimensional fiber protection network enables concrete to achieve synergistic effects throughout the stress process, from micro-crack suppression and meso-level energy dissipation to macro-level strength enhancement. Especially under complex environmental conditions such as freeze-thaw cycles, it effectively resists the accumulation of multi-scale damage, significantly improving the overall mechanical and durability properties of concrete. The surface modification of the three fibers further optimizes the interfacial bonding between the fibers and the cement matrix, ensuring the long-lasting effectiveness of this synergistic reinforcement.

[0036] 3. The concrete of this invention has excellent frost resistance and is particularly suitable for infrastructure construction in cold regions, such as bridges, roads, and tunnels. It can effectively reduce the damage to the structure caused by freeze-thaw cycles and extend its service life. Attached Figure Description

[0037] The accompanying drawings are provided to further explain the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a schematic diagram of the mixing device of the present invention;

[0039] Figure 2 For the present invention Figure 1 Enlarged view of point A;

[0040] Figure 3 This is a schematic diagram illustrating the engagement of the gear and the arc-shaped rack of the present invention.

[0041] Figure 4 This is a top view of the arc-shaped rotating plate of the present invention;

[0042] Figure 5 This is a schematic diagram illustrating the movement of the slider in this invention;

[0043] Figure 6 This is a schematic diagram showing the connection between the slider and the moving rod of the present invention.

[0044] In the figure: 1, mixing tank; 2, feed pipe; 3, driving motor; 4, arc-shaped rotating plate; 5, trapezoidal ring plate; 6, arc-shaped plate; 7, spiral blade; 8, moving rod; 9, mixing blade; 10, discharge port; 11, supporting rod; 12, extending rod; 13, rotating pipe; 14, gear two; 15, universal ball; 16, protrusion; 17, L-shaped plate; 18, gear ring; 19, rotating motor; 20, gear one; 21, arc-shaped rack; 22, sliding groove; 23, moving block; 24, spring one; 25, sliding block; 26, sliding block; 27, fixed pulley; 28, wire harness; 29, through groove; 30, hollow pipe. DETAILED DESCRIPTION

[0045] The technical solutions of the present application are further described below in combination with specific embodiments, but the protection scope of the present application is not limited to the following embodiments.

[0046] The cement is P·O 52.5 grade Portland cement; the fly ash is grade I fly ash; the silica ash is silica ash with a specific surface area greater than 20000 m 2 / kg; the water reducing agent is a polycarboxylic acid high-performance water reducing agent; the river sand is medium-coarse natural river sand with a fineness modulus of 2.7 and a clay content of less than 1%; the machine-made sand is a sealed machine-made sand with a fineness modulus of 2.9 and a clay content of less than 1%; the coarse aggregate is granite gravel with a particle size range of 5-25 mm and a needle flake particle content of 7.1%; the glass fiber has a diameter of 17 μm and a length of 6 mm; the polyvinyl alcohol fiber has a diameter of 30 μm and a length of 18 mm; and the steel fiber has a specification of 0.7×1×30 mm.

[0047] The preparation steps of the modified glass fiber are as follows: 55 parts of glass fiber is immersed in a 5% NaOH solution, heated to 60°C and stirred for 30 min for activation, and then washed with water to neutralization after activation; 7.5 parts of glycidyl methacrylate and 1.875 parts of acrylic acid are dissolved in 250 parts of an ethanol / water (volume ratio 1:5) mixed solution, the solution pH is adjusted to 6.5, the activated glass fiber is placed in the mixed solution, heated to 65°C under nitrogen atmosphere, and stirred, 25 parts of 2wt% ammonium persulfate solution and 10 parts of 0.5wt% ferrous sulfate solution are added dropwise, and the reaction is carried out for 3 h; after the reaction is completed, the pre-modified glass fiber is washed with ethanol and water, and vacuum dried; the dried pre-modified glass fiber is immersed in 2wt% KH550 silane coupling agent, treated at room temperature for 60 min, and dried after treatment, to obtain the modified glass fiber.

[0048] The preparation steps of the modified polypropylene fiber are specifically as follows: the dried polypropylene resin is placed in a closed double-shaft heating mixer, and heated to 180℃ until the resin is completely melted; under the protection of nitrogen, lithium-based ionic liquid LiNTf2 and glycidyl methacrylate are added while stirring, and then dicumyl peroxide is continuously added and uniformly stirred; the mass ratio of the polypropylene resin, lithium-based ionic liquid LiNTf2, glycidyl methacrylate and dicumyl peroxide is 100:3:5:0.2, to obtain a molten mixture; the molten mixture is extruded and granulated through a screw extruder, dried, to obtain modified polypropylene material; the modified polypropylene material is melt-spun through a silk-like machine, to obtain the modified polypropylene fiber.

[0049] The preparation steps of the modified steel fiber are specifically as follows: the steel fiber is cleaned with ethanol and dried; an ethanol / water (volume ratio 2:1) mixed solution containing 3% by mass of silane coupling agent KH560 is prepared, the pH is adjusted to 4.5, and the dried steel fiber is soaked therein, stirred at 50℃ for 2h, and then dried, to obtain the modified steel fiber.

[0050] Example 1

[0051] A preparation process of a concrete with excellent anti-freezing performance, comprising the following steps:

[0052] S1. The raw materials are weighed, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 6.9 parts and water 170 parts;

[0053] The composite fiber material is obtained by mixing modified glass fiber, modified polypropylene fiber and modified steel fiber at a mass ratio of 3:2:8;

[0054] The anti-freezing agent comprises propylene glycol, silane coupling agent, nano silicon dioxide, calcium acetate and polyethylene glycol phosphate, and the mass ratio is 4.5:0.4:0.5:0.2:0.3.

[0055] S2. The river sand, machine-made sand and coarse aggregate are mixed uniformly to obtain an aggregate mixture;

[0056] S3. The composite fiber is added to the aggregate mixture and mixed uniformly, and then the cement, fly ash and silica fume are added and mixed uniformly to obtain a premix;

[0057] S4. The water reducing agent and the anti-freezing agent are mixed uniformly in water to obtain an additional liquid;

[0058] S5. The additional liquid is added to the premix and stirred uniformly, to obtain the concrete with excellent anti-freezing performance.

[0059] Example 2

[0060] The difference between this example and Example 1 is that in step S1, the raw materials are weighed, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 30 parts, anti-freezing agent 6.9 parts, and water 170 parts;

[0061] The composite fiber material is obtained by mixing modified glass fiber, modified polypropylene fiber, and modified steel fiber at a mass ratio of 4:2:6.

[0062] The rest is the same as Example 1.

[0063] Example 3

[0064] The difference between this example and Example 1 is that in step S1, the raw materials are weighed, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 8.5 parts, and water 170 parts;

[0065] The rest is the same as Example 1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that in step S1, the raw materials are weighed, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, and water 170 parts, without adding anti-freezing agent;

[0068] The rest is the same as Example 1.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that in step S1, the raw materials are weighed, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 6.9 parts, and water 170 parts;

[0071] The anti-freezing agent includes propylene glycol, silane coupling agent, and nano silicon dioxide at a mass ratio of 4.5:0.4:0.5.

[0072] The rest is the same as Example 1.

[0073] Comparative Example 3

[0074] The difference between the present comparative example and Example 1 is that in Step S1, the raw materials are weighed out in parts by weight, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, anti-freezing agent 6.9 parts, and water 170 parts, without adding the composite fiber material;

[0075] The rest is the same as Example 1.

[0076] Comparative Example 4

[0077] The difference between the present comparative example and Example 1 is that in Step S1, the raw materials are weighed out in parts by weight, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 6.9 parts, and water 170 parts;

[0078] The composite fiber material is obtained by mixing unmodified glass fiber, unmodified polypropylene fiber, and unmodified steel fiber in a mass ratio of 3:2:8;

[0079] The rest is the same as Example 1.

[0080] Comparative Example 5

[0081] The difference between the present comparative example and Example 1 is that in Step S1, the raw materials are weighed out in parts by weight, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 6.9 parts, and water 170 parts;

[0082] The composite fiber material is obtained by mixing modified polypropylene fiber and modified steel fiber in a mass ratio of 5:8;

[0083] The rest is the same as Example 1.

[0084] Comparative Example 6

[0085] The difference between the present comparative example and Example 1 is that in Step S1, the raw materials are weighed out in parts by weight, including cement 342 parts, river sand 486 parts, machine-made sand 194 parts, coarse aggregate 868 parts, fly ash 94 parts, silica fume 26 parts, water reducing agent 4.8 parts, composite fiber material 33 parts, anti-freezing agent 6.9 parts, and water 170 parts;

[0086] The composite fiber material is obtained by mixing modified glass fiber and modified steel fiber in a mass ratio of 5:8;

[0087] The rest is the same as Example 1.

[0088] Test Example

[0089] Performance tests were conducted on the concrete prepared in the examples and comparative examples:

[0090] 1. Compressive strength detection

[0091] Standard test blocks were prepared according to GB / T50081-2019 Standard Test Methods for Mechanical Properties of Ordinary Concrete, and the compressive strength of the standard test blocks cured for 28 days was measured.

[0092] 2. Flexural strength detection

[0093] Standard test blocks were prepared according to GB / T50081-2019 Standard Test Methods for Mechanical Properties of Ordinary Concrete, and the flexural strength of the standard test blocks cured for 28 days was measured.

[0094] 3. Freeze-thaw cycle test

[0095] Standard test blocks were prepared according to GB / T50082-2019 Standard Test Methods for Long-term Performance and Durability of Ordinary Concrete, and the test blocks were subjected to 100 freeze-thaw treatments according to the slow freezing method. After freeze-thaw treatment, the mass loss rate and compressive strength loss rate of each test block were detected.

[0096] The test results are shown in Table 1.

[0097] Table 1

[0098]

[0099] As can be seen from the results in Table 1, the concrete prepared in the examples of the present application realizes excellent mechanical properties and durability by optimizing the mix design, multi-level modified fiber reinforcement system and the addition of composite anti-freezing agent, and its anti-freezing performance is significantly superior to that of the concrete in the comparative examples.

[0100] Although the multi-level modified fiber reinforcement system is retained in Comparative Example 1, the protective effect of the anti-freezing agent is lacking, resulting in a significant acceleration of the performance degradation of the concrete under repeated freeze-thaw action, which indicates that the anti-freezing agent of the present application plays a key role in improving the anti-freezing performance of the concrete.

[0101] The anti-freezing agent used in Comparative Example 2 retains the core anti-freezing components, so that the concrete still has certain anti-freezing performance, but the anti-freezing agent removes calcium acetate and polyethylene glycol phosphate, resulting in a small decrease in the mechanical properties of the concrete and a moderate decrease in the anti-freezing performance. In the anti-freezing agent of the present application, calcium acetate can combine with water in cement to reduce the freezing of water and reduce the expansion pressure of water, and can also accelerate the hydration process of cement to improve the early strength of concrete, which helps to achieve preliminary hardening of concrete faster in cold environments. Polyethylene glycol phosphate is a polymer with surface activity and wetting properties, which can reduce the surface tension of the concrete surface, so that the cement matrix is more uniformly distributed during the hydration process, forming a more lost cement matrix. In addition, at low temperatures, polyethylene glycol phosphate can reduce the generation and growth rate of ice crystals, thereby preventing excessive expansion of ice crystals and causing damage to the concrete structure. This helps to reduce structural damage during freeze-thaw cycles.

[0102] In Comparative Example 3, no composite fiber material is added, and the flexural strength of the concrete is significantly reduced. The composite fiber material can effectively disperse stress and limit crack propagation under bending and tensile action, thereby improving the flexural strength. In the freeze-thaw cycle experiment, the composite fiber material improves the cohesion and toughness of the concrete, and can reduce the damage in the freeze-thaw cycle. Therefore, the lack of composite fiber material significantly reduces the anti-freezing performance of the concrete.

[0103] In Comparative Example 4, the composite fiber material is added, but the fiber material is not modified. The unmodified composite fiber has poor bonding force with the cement matrix and is easily dispersed unevenly in the concrete, thereby affecting the strength of the concrete. Since the unmodified fiber has poor bonding force with the cement matrix, it cannot effectively control crack propagation, which can lead to high water permeability and water expansion damage in the freeze-thaw cycle, thereby reducing the anti-freezing performance of the concrete.

[0104] In Comparative Example 5, the type of composite fiber material is adjusted, and the amount of modified polypropylene fiber is increased, and the micro-enhancing effect and multi-scale synergistic effect of modified glass fiber are lacking, resulting in a significant decrease in the mechanical properties of the concrete. The deformation ability of the modified polypropylene fiber is beneficial to absorbing freeze-thaw stress, and the modified steel fiber provides macroscopic constraint disadvantage, but the lack of micro-crack control of the modified glass fiber leads to a decrease in the anti-freezing performance of the concrete.

[0105] In Comparative Example 6, the type of composite fiber material is adjusted, and the amount of modified polypropylene fiber is increased, and the amount of modified glass fiber is increased. Modified glass fiber and modified steel fiber both have high strength, but lack the mesoscale synergistic effect and plastic deformation ability of modified polyethylene fiber, resulting in a slight decrease in the mechanical properties of the concrete. The anti-freezing performance of the concrete is significantly reduced, mainly due to the lack of strain coordination of PP fiber.

[0106] In this invention, modified glass fibers, modified polypropylene fibers, and modified steel fibers form a three-dimensional protective network in spatial distribution, and achieve synergistic crack control throughout the entire process in temporal sequence. When microcracks begin to initiate, glass fibers first play a role in limiting their formation; as cracks propagate, PP fibers absorb energy through plastic deformation, slowing the crack propagation rate; as cracks further develop, steel fibers assume the main load transfer and crack bridging roles. This multi-scale, multi-stage synergistic effect enables concrete to exhibit excellent comprehensive performance under external loads and environmental influences. Especially during repeated freeze-thaw cycles, this synergistic effect can effectively inhibit the accumulation of internal damage and maintain the integrity and durability of concrete. The modification treatment further optimizes the interfacial characteristics between various fibers and the matrix, ensuring the long-term effectiveness of this synergistic effect.

[0107] Example 4

[0108] Based on the above embodiments 1-3, such as Figures 1-6 As shown, in steps S2, S3, and S5, a mixing device is used for stirring and mixing. The mixing device includes a mixing tank 1. Several support rods 11 are fixedly installed at the lower end of the mixing tank 1. A drive motor 3 is fixedly installed at the upper end of the mixing tank 1. The lower output end of the drive motor 3 extends into the mixing tank 1. An arc-shaped rotating plate 4 is fixedly connected to the lower output end of the drive motor 3. A trapezoidal ring plate 5 is fixedly installed on the upper inner wall of the mixing tank 1. Both ends of the arc-shaped rotating plate 4 are rotatably connected to the trapezoidal ring plate 5. A rotating tube 13 is installed at the eccentric position of the arc-shaped rotating plate 4. Several hollow tubes 30 are fixedly installed on the rotating tube 13. An arc-shaped plate 6 is slidably installed on the hollow tube 30. Several protruding rods 12 are fixedly installed on the arc-shaped plate 6. A moving rod 8 is installed inside the rotating tube 13. A spiral blade 7 is fixedly installed on the moving rod 8. A mixing blade 9 is fixedly installed at the lower end of the moving rod 8. A feed pipe 2 is provided through the left and right sides of the upper surface of the mixing tank 1. A discharge port 10 is opened at the lower end of the mixing tank 1.

[0109] The working principle and beneficial effects of the above technical solution are as follows: The raw materials (the raw materials recorded in steps S2, S3 and S5) are fed into the mixing tank 1 through the feed pipe 2. The drive motor 3 is started, and the drive motor 3 drives the arc-shaped rotating plate 4 to rotate. The arc-shaped rotating plate 4 drives the rotating tube 13 to start revolving. The rotating tube 13 drives the moving rod 8, the arc-shaped plate 6 and several extension rods 12 to revolve. At the same time, the moving rod 8 drives the mixing blade 9 and the spiral blade 7 to revolve. The revolving of the arc-shaped plate 6, several extension rods 12 and the mixing blade 9 will stir the raw materials in the mixing tank 1, resulting in higher stirring efficiency and faster stirring speed.

[0110] Example 5

[0111] Based on the above embodiment 4, as shown in Figures 1-6 The arc-shaped rotating plate 4 is provided as a hollow structure, a sliding groove 22 is formed on the arc-shaped rotating plate 4, a moving block 23 is slidably arranged in the sliding groove 22, a rotating pipe 13 is rotatably arranged on the moving block 23, an arc-shaped rack 21 is fixedly arranged on the moving block 23, the arc-shaped rack 21 is slidably arranged in the arc-shaped rotating plate 4, a rotating motor 19 is fixedly arranged on the front side of the arc-shaped rotating plate 4, the rear output end of the rotating motor 19 extends into the arc-shaped rotating plate 4, a gear one 20 is fixedly connected to the rear output end of the rotating motor 19, the gear one 20 is in meshing connection with the arc-shaped rack 21, a gear ring 18 is also fixedly arranged in the trapezoidal ring plate 5, and a gear two 14 is fixedly arranged on the rotating pipe 13; the moving rod 8 extends out of the rotating pipe 13, a connecting key is arranged on the moving rod 8, a key groove is arranged on the gear two 14, the moving rod 8 is in sliding connection with the gear two 14 through the cooperation of the connecting key and the key groove, a universal ball 15 is mounted on the upper end of the moving rod 8, an L-shaped plate 17 is fixedly arranged on the arc-shaped rotating plate 4, two protruding blocks 16 are fixedly arranged on the L-shaped plate 17, and the protruding blocks 16 are in cooperation with the universal ball 15.

[0112] The working principle and beneficial effects of the above technical solution are as follows: the rotating motor 19 is started, the rotating motor 19 drives the gear one 20 to rotate, the gear one 20 drives the arc-shaped rack 21 to move, the arc-shaped rack 21 drives the moving block 23 to move, and the moving block 23 drives the rotating pipe 13 to move; when the rotating pipe 13 moves to the limit position, the gear two 14 is in meshing connection with the gear ring 18; with the rotation of the arc-shaped rotating plate 4, the gear two 14 will start to rotate, the gear two 14 will drive the rotating pipe 13 to rotate, and the rotating pipe 13 drives the plurality of hollow pipes 30, the plurality of arc-shaped plates 6, the plurality of protruding rods 12, the helical blades 7 and the mixing leaves 9 to start to rotate, so as to stir the input raw materials; at the same time when the plurality of hollow pipes 30, the plurality of arc-shaped plates 6, the plurality of protruding rods 12, the helical blades 7 and the mixing leaves 9 start to rotate, the plurality of hollow pipes 30, the plurality of arc-shaped plates 6, the plurality of protruding rods 12, the helical blades 7 and the mixing leaves 9 also perform revolution, so that the stirring mode of rotation and revolution can effectively improve the mixing effect and the mixing rate, and the arrangement of the helical blades 7 can transport the raw materials in the lower part of the mixing tank 1 to the upper part, so as to form overturning, and the mixing effect will be better; at the same time, when the rotating pipe 13 moves, the universal ball 15 on the moving rod 8 will be in contact with the protruding block 16, so as to realize the movement of the moving rod 8 in the rotating pipe 13, and further change the positions of the helical blades 7 and the mixing leaves 9, thereby further accelerating the mixing rate.

[0113] Embodiment 6

[0114] Based on the above embodiment 5, as shown in Figures 1-6As shown, the moving rod 8 is fixedly provided with a sliding block 25, the sliding block 25 is in sliding connection with the inner wall of the rotating pipe 13, the moving rod 8 is extended out of the rotating pipe 13 by sliding downward, the lower end of the sliding block 25 is fixedly provided with a spring 24, the spring 24 is sleeved on the moving rod 8, the lower end of the spring 24 is fixedly connected with the lower inner wall of the rotating pipe 13; four hollow pipes 30 are provided, the hollow pipes 30 are arranged at an angle of 30 degrees with the rotating pipe 13, the hollow pipes 30 are connected with the rotating pipe 13 in penetration, the hollow pipes 30 are provided with a pulley 27, the hollow pipes 30 are provided with a through groove 29, the through groove 29 is slidably provided with a sliding block 26, the sliding block 26 is fixedly provided with an arc plate 6, the sliding block 26 is fixedly provided with a spring 2, the spring 2 is fixedly connected with the end of the hollow pipe 30 away from the rotating pipe 13, the sliding block 26 is further fixedly provided with a wire harness 28, the wire harness 28 is fixedly connected with the sliding block 25 by passing around the pulley 27, the wire harness 28 is provided with a sealing gasket at the penetration position of the through groove 29.

[0115] The working principle and beneficial effects of the above technical scheme are as follows: when the moving rod 8 moves in the rotating pipe 13, the moving rod 8 drives the sliding block 25 to move downward, the sliding block 25 pulls the wire harness 28, the wire harness 28 drives the sliding block 26 to move, so that the arc plate 6 moves towards the moving rod 8, forming an approximate pipeline (the specific shape of the arc plate 6 is not shown in the figure), so that the transfer of the lower part of the spiral blade 7 is more rapid, further accelerating the mixing rate; through the above structure, the self-rotation mixing can be carried out while the revolution stirring is carried out, and the positions of the arc plate 6 and the extending rod 12 can be changed, so that the mixing rate is faster, the cooperation degree of each part is higher, and the practicality is stronger.

[0116] Finally, it should be noted that: the above-described embodiments only express several embodiments of the present application, and are not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art without departing from the concept of the present application shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A process for the production of concrete with excellent frost resistance, characterized in that, The method comprises the following steps: S1. Measuring the raw materials by weight parts, including cement 330-350 parts, fine aggregate 650-700 parts, coarse aggregate 850-900 parts, fly ash 80-100 parts, silica fume 20-40 parts, water reducing agent 3-8 parts, composite fiber material 20-35 parts, anti-freezing agent 5-10 parts and water 160-180 parts; S2. Mixing the fine aggregate and the coarse aggregate uniformly to obtain an aggregate mixture; S3. Adding the composite fiber to the aggregate mixture, mixing uniformly, and then adding the cement, fly ash and silica fume, mixing uniformly to obtain a premix; S4. Mixing the water reducing agent and the anti-freezing agent in water to obtain an additional liquid; S5. Adding the additional liquid to the premix and stirring uniformly to obtain the concrete with excellent anti-freezing performance; The composite fiber material is obtained by mixing modified glass fiber, modified polypropylene fiber and modified steel fiber according to the mass ratio of (2-5):(1-3):(5-10); The preparation steps of the modified glass fiber are as follows: 50-60 parts of glass fiber is immersed in 5% NaOH solution, and stirred and activated at 60℃ for 30 min; after activation, the glass fiber is washed to neutral with water; 7-8 parts of glycidyl methacrylate and 1.5-2.0 parts of acrylic acid are dissolved in 250 parts of an ethanol / water mixed solution, and the pH of the solution is adjusted to 6-7; the activated glass fiber is placed in the mixed solution, heated to 65℃ under nitrogen atmosphere, and stirred; 2wt% ammonium persulfate solution and 0.5wt% ferrous sulfate solution are added dropwise, and the reaction is carried out for 2-3h; after the reaction is completed, the pre-modified glass fiber is washed with ethanol and water, and vacuum dried; the dried pre-modified glass fiber is immersed in 2wt% KH550 silane coupling agent, treated at room temperature for 30-60 min, and dried after treatment to obtain the modified glass fiber; The preparation steps of the modified polypropylene fiber are as follows: the dried polypropylene resin is placed in a closed double-shaft heating mixer, heated to 180℃ until the resin is completely melted, and then lithium-based ionic liquid LiNTf2 and glycidyl methacrylate are added under nitrogen protection while stirring; after mixing uniformly, dicumyl peroxide is added, and the mixture is stirred uniformly to obtain a molten mixture; the molten mixture is extruded and granulated through a screw extruder, dried to obtain the modified polypropylene material; The modified polypropylene material is melt-spun through a silk-like machine to obtain the modified polypropylene fiber; The preparation steps of the modified steel fiber are as follows: the steel fiber is cleaned with ethanol and dried; an ethanol / water mixed solution containing silane coupling agent KH560 is prepared, and the pH is adjusted to 4.0-5.5; the dried steel fiber is immersed in the solution, stirred at 45-55℃ for 1-2h, and then dried to obtain the modified steel fiber; The anti-freezing agent comprises propylene glycol, silane coupling agent, nano silicon dioxide, calcium acetate and polyethylene glycol phosphate, and the mass ratio of propylene glycol, silane coupling agent, nano silicon dioxide, calcium acetate and polyethylene glycol phosphate is (4-5):(0.3-0.5):(0.4-0.6):(0.2-0.3):(0.2-0.4).

2. The process for preparing concrete having excellent freeze resistance according to claim 1, characterized in that, The mass ratio of the polypropylene resin, lithium-based ionic liquid LiNTf2, glycidyl methacrylate, and dicumyl peroxide is 100: (2-3.5): (3-5): (0.1-0.3).

3. The preparation process of the concrete with excellent frost resistance according to claim 1, characterized in that, The cement is one or more of Portland cement, aluminate cement, and sulfoaluminate cement; The fine aggregate is a mixture of river sand and machine-made sand, and the weight ratio of the river sand to the machine-made sand is (2-3): 1; The fineness modulus of the river sand is 2.5-2.9, and the clay content is less than 1%; The fineness modulus of the machine-made sand is 2.7-3.0, and the clay content is less than 1%; The coarse aggregate is one or both of gravel and pebble, the particle size range is 5-25 mm, the crushing index is less than 5%, and the content of needle and flake particles is less than 8%; The fly ash is grade I fly ash; The silica fume has a specific surface area greater than 20000 m 2 / kg of silica fume; The water reducing agent is a polycarboxylic acid high-performance water reducing agent.

4. The process for preparing the concrete having excellent freeze resistance according to claim 1, wherein the process is characterized by, In steps S2, S3 and S5, a mixing device is used for stirring and mixing, which comprises a mixing tank (1), a plurality of support rods (11) are fixedly arranged at the lower end of the mixing tank (1), a driving motor (3) is fixedly arranged at the upper end of the mixing tank (1), the lower side output end of the driving motor (3) extends into the mixing tank (1) in a rotating manner, the lower side output end of the driving motor (3) is fixedly connected with an arc-shaped rotating plate (4), a trapezoidal ring plate (5) is fixedly arranged on the upper inner wall of the mixing tank (1), both ends of the arc-shaped rotating plate (4) are rotatably connected with the trapezoidal ring plate (5), a rotating pipe (13) is arranged at the eccentric position of the arc-shaped rotating plate (4), a plurality of hollow pipes (30) are fixedly arranged on the rotating pipe (13), an arc-shaped plate (6) is slidably arranged on the hollow pipe (30), a plurality of extension rods (12) are fixedly arranged on the arc-shaped plate (6), a moving rod (8) is arranged in the rotating pipe (13), a helical blade (7) is fixedly arranged on the moving rod (8), and a mixing blade (9) is fixedly arranged at the lower end of the moving rod (8); a feeding pipe (2) is arranged through the upper surface of the mixing tank (1) in a left-right direction, and a discharge port (10) is arranged at the lower end of the mixing tank (1).

5. The process for preparing concrete having excellent freeze resistance according to claim 4, characterized in that, The arc-shaped rotating plate (4) is provided as a hollow structure, and a sliding groove (22) is formed on the arc-shaped rotating plate (4). A moving block (23) is slidably arranged in the sliding groove (22). A rotating pipe (13) is rotatably arranged on the moving block (23). An arc-shaped rack (21) is fixedly arranged on the moving block (23). The arc-shaped rack (21) is slidably arranged in the arc-shaped rotating plate (4). A rotating motor (19) is fixedly arranged on the front side of the arc-shaped rotating plate (4). The rear output end of the rotating motor (19) extends into the arc-shaped rotating plate (4) and is fixedly connected with a gear one (20). The gear one (20) is in meshing connection with the arc-shaped rack (21). A gear ring (18) is also fixedly arranged in the trapezoidal ring plate (5). A gear two (14) is fixedly arranged on the rotating pipe (13).

6. The process for preparing concrete having excellent freeze resistance according to claim 5, characterized in that, A moving rod (8) extends upward out of the rotating pipe (13). A connecting key is arranged on the moving rod (8). A key groove is arranged on the gear two (14). The moving rod (8) is in sliding connection with the gear two (14) through the cooperation of the connecting key and the key groove. A universal ball (15) is mounted on the upper end of the moving rod (8). An L-shaped plate (17) is fixedly arranged on the arc-shaped rotating plate (4). Two protrusions (16) are fixedly arranged on the L-shaped plate (17). The protrusions (16) are in cooperation with the universal ball (15). A sliding block (25) is fixedly arranged on the moving rod (8). The sliding block (25) is in sliding connection with the inner wall of the rotating pipe (13). The moving rod (8) extends downward out of the rotating pipe (13). A spring one (24) is fixedly arranged at the lower end of the sliding block (25). The spring one (24) is sleeved on the moving rod (8). The lower end of the spring one (24) is fixedly connected with the lower inner wall of the rotating pipe (13). Four hollow pipes (30) are arranged. The hollow pipes (30) are arranged at an angle of 30 degrees with the rotating pipe (13). The hollow pipes (30) are in through connection with the rotating pipe (13). A fixed pulley (27) is mounted in the hollow pipe (30). A through groove (29) is arranged on the hollow pipe (30). A sliding block (26) is slidably arranged in the through groove (29). An arc-shaped plate (6) is fixedly arranged on the sliding block (26). A spring two is fixedly arranged on the sliding block (26). The spring two is fixedly connected with the end of the hollow pipe (30) away from the rotating pipe (13). A wire harness (28) is also fixedly arranged on the sliding block (26). The wire harness (28) is fixedly connected with the sliding block (25) by passing around the fixed pulley (27). A sealing gasket is arranged at the through portion of the wire harness (28) and the through groove (29).

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