Flexible fiber concrete cover plate and preparation method thereof

Abstract

The invention belongs to the technical field of engineering materials, and particularly relates to a flexible fiber concrete cover plate and a preparation method thereof. The raw materials of the cover plate include, by weight, 150-180 parts of cement, 170-220 parts of water, 250-300 parts of river sand, 50-100 parts of fine stone, 20-30 parts of polypropylene fiber, 10-15 parts of polyacrylamide, 15-25 parts of polyurethane elastomer particles, 18-20 parts of hydrophobically modified polyacrylate copolymer emulsion, 30-50 parts of expansion agent, 8-25 parts of air entraining agent, and 18-25 parts of polyacrylic acid salt. The invention can increase the bonding force between the polypropylene fiber and the cement matrix and improve the reinforcing effect of the polypropylene fiber through the action between the various components of the concrete, and starting from the microscopic causes of concrete cracking, polyacrylamide and polyacrylic acid salt are added in a targeted manner to effectively improve the anti-cracking performance of the concrete cover plate.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering materials, and particularly relates to a flexible fiber concrete cover plate and a preparation method thereof. Background Art

[0002] Trench covers are engineering materials cast with cement concrete and are widely used in municipal roads, garden facilities, residential areas, schools, stadiums and other places. Traditional cement concrete is a rigid material with the characteristics of high strength, good durability and low cost. However, its tensile strength is much lower than its compressive strength, and the ratio of tensile strength to compressive strength is only 6%. It is brittle and its plasticity is significantly reduced. Because brittle failure can occur at any time, the span of the concrete structure cannot be increased too much. When the structure is bent, cracks begin to appear when the load is equal to 15%-20% of the failure load (the stress of the steel bar is much less than the yield limit at this time). As the cracks expand, the impermeability of the structure will decrease, resulting in a shortened service life. In addition, cement concrete materials have poor toughness and poor resistance to impact, cracking and fatigue, which restricts the application of cement concrete materials. With the development of chemical technology, the emergence of artificial low elastic modulus high-strength fibers has led people to explore flexible fiber concrete.

[0003] The addition of flexible fibers not only improves the tensile, compressive, splitting and bending strength of concrete, but also has a significant effect on other properties, including the improvement of the freeze-thaw resistance of fiber concrete, and the enhancement of the wear resistance and anti-fragmentation performance of concrete.

[0004] However, the adsorption and bonding force between flexible fibers (such as polypropylene fibers) and cement-based interfaces is weak, which weakens the reinforcement effect on concrete to a certain extent. The current solution is usually to perform surface modification on flexible fibers to increase the bonding strength, such as invention patents CN110256023B and CN111592252A, etc. However, the modification process will use other reagents, which further increases the cost and is not in line with the concept of green environmental protection. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a flexible fiber concrete cover plate and a preparation method thereof, so as to achieve the effect of effectively exerting the fiber function and improving the anti-cracking performance of the concrete cover plate without modifying the flexible fiber.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A flexible fiber concrete cover plate comprises a plurality of cover plate bodies, wherein two adjacent cover plate bodies are connected by an I-shaped connector; the cover plate body is in the form of a rectangular parallelepiped; a mounting groove is provided in the middle of the two long sides of the cover plate body; two pairs of positioning grooves are symmetrically provided on the upper and lower surfaces of the two long sides of the cover plate body, and the two pairs of positioning grooves are arranged at the same intervals on both sides of the mounting groove; two adjacent cover plate bodies are connected to form a group of cover plates by the I-shaped connector and the positioning grooves.

[0008] Furthermore, an anti-slip strip is provided on the upper surface of the cover body, and a groove is provided on the lower surface of the cover body.

[0009] Furthermore, the I-shaped connector includes a first connector and a second connector; the first connector and the second connector are both T-shaped, and the middle of the first connector and the second connector are both provided with connecting holes, and the first connector and the second connector are formed by fixing members passing through the connecting holes.

[0010] Furthermore, the fixing member is a triangular bolt, and the first connecting member and the second connecting member are connected via the triangular bolt and a matching hexagonal nut to form the I-shaped connecting member.

[0011] Furthermore, two ends of the fixing member are sunk into the connecting holes of the first connecting member and the second connecting member.

[0012] Furthermore, the positioning grooves corresponding to two adjacent cover plate bodies are respectively clamped in the grooves on both sides of the I-shaped connector.

[0013] Furthermore, the four corners of the cover body are chamfered.

[0014] In parts by weight, the raw materials of the cover plate include: 150-180 parts of cement, 170-220 parts of water, 250-300 parts of river sand, 50-100 parts of fine stone, 20-30 parts of polypropylene fiber, 10-15 parts of polyacrylamide, 15-25 parts of polyurethane elastomer particles, 18-20 parts of hydrophobically modified polyacrylate copolymer emulsion, 30-50 parts of expansion agent, 8-25 parts of air entraining agent, and 18-25 parts of polyacrylate.

[0015] Among them, the hydrophobically modified polyacrylate copolymer emulsion can be HY-302 and HY-303 produced by Mayer Chemical.

[0016] Furthermore, in parts by weight, the raw materials of the cover plate include: 150-160 parts of cement, 170-190 parts of water, 250-290 parts of river sand, 70-90 parts of fine stone, 25 parts of polypropylene fiber, 15 parts of polyacrylamide, 20 parts of polyurethane elastomer particles, 18 parts of hydrophobically modified polyacrylate copolymer emulsion, 40 parts of expansion agent, 15 parts of air entraining agent, and 25 parts of polyacrylate.

[0017] Furthermore, the polyacrylate is compounded by sodium polyacrylate and calcium polyacrylate in a molar ratio of 1:1.

[0018] Furthermore, the particle size of the fine stone is 8-10 mm.

[0019] Furthermore, the polypropylene fiber is a monofilament fiber with a length of 20-25 mm, a diameter of 40-50 μm, and a density of 850-900 kg / m 3 , elastic modulus is 3-3.8GPa, tensile strength is 300-600MPa, and elongation at break is 15-35%.

[0020] Furthermore, the particle size of the polyurethane elastomer particles is 0.01-0.05 mm.

[0021] A method for preparing a flexible fiber concrete cover plate comprises the following steps:

[0022] S1. Weigh the required raw materials according to the raw material ratio of a flexible fiber concrete cover plate according to any one of claims 1 to 5;

[0023] S2. The polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are mixed and set aside;

[0024] S3. The cement, water, river sand, fine stone, polyacrylamide, expansion agent, air entraining agent and polyacrylic acid salt are mixed and stirred uniformly, and then the polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are added and dispersed uniformly to obtain a concrete slurry;

[0025] S4. Pour the concrete slurry into a cover plate mold, and demould it after curing to obtain the flexible fiber concrete cover plate.

[0026] Furthermore, it is characterized in that, in step S4, the maintenance includes the following steps:

[0027] S41. After the concrete has initially set, sprinkle water on its surface and cover it with an insulation film for 4-5 days;

[0028] S42. Remove the thermal insulation film and store water in the concrete for curing for 9-10 days.

[0029] The invention also provides an application of a flexible fiber concrete cover plate in a construction project.

[0030] Studies have found that during the hardening process of concrete cover slabs, various shrinkages (such as chemical shrinkage, temperature shrinkage, plastic shrinkage, dry shrinkage and autogenous shrinkage, etc.) increase, causing many micro cracks in the concrete, which is the main reason for the poor crack resistance of concrete.

[0031] The present invention adds polyacrylamide to the concrete cover plate component, which has a certain water retention performance and can reduce the loss of water during the cement hardening process, and to a certain extent avoids the capillary channels generated between the bonding interface between the aggregate and the hardened body and the inside of the hardened body, thereby reducing the cracks generated at the bonding interface and inside the hardened body due to capillary pressure; at the same time, due to the hydrophilicity of polyacrylamide, it also has a certain promoting effect on the enhancement of the bonding force between the polypropylene fiber and the cement matrix.

[0032] During the preparation of the present invention, polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are first mixed uniformly, and a certain amount of hydrophobically modified polyacrylate copolymer emulsion is attached to the surface of polypropylene fiber and polyurethane elastomer particles. When the mixture is mixed with other raw materials, due to the hydrophobic effect of the emulsion, the emulsion attached to the surface of polypropylene fiber and polyurethane elastomer particles is not easy to lose. During the cement hardening process, the emulsion reacts chemically with the matrix, and micelle structures are generated within or between molecules, resulting in an increase in the viscosity of the emulsion or solidification, forming a close connection with the matrix, thereby increasing the connection between the polypropylene fiber, polyurethane elastomer and cement matrix. In addition to having the function of filling pores, the polyurethane elastomer can deform when the concrete shrinks, resist a part of the force, and delay the cracking of the concrete.

[0033] When external carbon dioxide gas enters the interior of concrete along the pores, it may react with calcium hydroxide generated by cement hydration to generate calcium carbonate. Compared with calcium hydroxide, the volume of calcium carbonate is reduced by 12%, which is also the reason for shrinkage and cracking of concrete. The present invention adds polyacrylate to the components, wherein calcium polyacrylate can combine with free calcium ions, reduces the number of free calcium ions, and can inhibit the generation of calcium carbonate to a certain extent. Sodium polyacrylate is weakly alkaline and is distributed in the pores of concrete to neutralize carbon dioxide and prevent it from reacting with calcium hydroxide.

[0034] The beneficial effects of the present invention are as follows: the present invention can increase the bonding force between polypropylene fibers and cement matrix and enhance the reinforcing effect of polypropylene fibers through the interaction between various components of concrete, and based on the microscopic causes of concrete cracking, specifically add polyacrylamide and polyacrylate, etc., to effectively enhance the anti-cracking effect of the concrete cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A bottom view of the cover plate body structure prepared by the present invention;

[0036] Figure 2 A top view of the cover plate body structure prepared by the present invention;

[0037] Figure 3 For the present invention Figure 1 AA section view;

[0038] Figure 4 For the present invention Figure 1 BB cross-sectional view;

[0039] Figure 5 For the present invention Figure 1 CC section view;

[0040] Figure 6 It is a front view of a T-shaped connector of the present invention;

[0041] Figure 7 A top view of a T-shaped connector of the present invention;

[0042] Figure 8 A bottom view of a T-shaped connector of the present invention;

[0043] Fig. 9 It is a schematic diagram of the connection of several cover plate bodies of the present invention;

[0044] Fig.10 for Fig. 9 A magnified view of the local structure;

[0045] In the figure: 1. Cover plate body; 2. I-shaped connecting piece; 21. First connecting piece; 22. Second connecting piece; 23. Connecting hole; 3. Anti-slip strip; 4. Groove; 5. Mounting groove; 6. Positioning groove; 7. Triangular bolt. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0047] In the following embodiments, the polyacrylate is compounded by sodium polyacrylate and calcium polyacrylate in a molar ratio of 1:1, the particle size of the fine stone is 8-10 mm, the polypropylene fiber is purchased from Sichuan Jiabanghui New Materials Co., Ltd., the particle size of the polyurethane elastomer particles is 0.01-0.05 mm, the cement is po42.5 cement, the hydrophobically modified polyacrylate copolymer emulsion is HY-302 produced by Maier Chemical, and the expander and air entraining agent are purchased from the market.

[0048] Example 1

[0049] like Figure 1-10As shown, this embodiment provides a flexible fiber concrete cover plate connection structure for a cable trench, including a plurality of cover plate bodies 1, two adjacent cover plate bodies 1 are connected by an I-shaped connector 2; the cover plate body 1 is a rectangular parallelepiped; the upper and lower surfaces of the two long sides of the cover plate body 1 are symmetrically provided with two pairs of positioning grooves 6, and the two pairs of positioning grooves 6 are arranged at the same interval on both sides of the installation groove 5; the two adjacent cover plate bodies 1 are connected to form a group of cover plates by the connector and the positioning groove 6. As a preferred embodiment, the upper surface of the cover plate body 1 is provided with an anti-slip strip 3, and the lower surface of the cover plate body 1 is provided with a groove 4; the middle part of the two long sides of the cover plate body 1 is provided with an installation groove 5.

[0050] A cable trench flexible fiber concrete cover plate connection structure, wherein the upper surface of the cover plate body 1 is provided with a raised anti-slip strip 3 to improve the friction of the upper surface of the cover plate body 1 and prevent workers from accidentally slipping; a groove 4 is provided on the lower surface of the cover plate body 1 to reduce the mass of the cover plate body 1 and improve the economic effect; the installation grooves 5 provided on the two long sides of the cover plate body 1 are convenient for lifting the cover plate body 1 by tools. Several cover plate bodies 1 are connected into a group of cover plates by an I-shaped connector 2. On the one hand, it prevents a single cover plate body 1 from being damaged by external forces in terms of its installation stability; on the other hand, several cover plate bodies 1 constitute a group of cover plates to prevent the loss of the cover plate body 1. The device has a simple structure, can improve the stability of the installation of the cover plate body 1, and has a certain cable theft prevention effect. As a preferred embodiment, the cover body 1 is a rectangular parallelepiped with a long side of 790 cm, a width of 490 cm, and a height of 25 cm. The lower surface of the cover body 1 is provided with 8 grooves 4 with a length of 220 cm, a width of 120 cm, and a depth of 13 cm, which are arranged in a matrix, and the middle of the rectangular parallelepiped is not provided with a groove 4. The height of the raised anti-slip strip 3 is 2 cm; the mounting groove 5 is rectangular, 300 cm long, 9 cm wide, and runs through the cover body 1; the positioning groove 6 is 40 cm long, 25 cm wide, and 4 cm deep, and is symmetrically arranged on the upper and lower surfaces; two pairs of positioning grooves 6 are arranged on both sides of the mounting groove 5 at a spacing of 77 cm. The groove 4, the anti-slip strip 3, the mounting groove 5, and the positioning groove 6 are all chamfered.

[0051] The I-shaped connector 2 includes a first connector 21 and a second connector 22; the first connector 21 and the second connector 22 are both T-shaped, and a connecting hole 23 is provided in the middle of the first connector 21 and the second connector 22, and the first connector 21 and the second connector 22 are connected through a fixing member through the connecting hole 23 to form the I-shaped connector 2. As a preferred embodiment, the first connector 21 and the second connector 22 have the same outer dimensions, and the connecting holes 23 provided in the two match the shape and size of the fixing member; specifically, the first connector 21 and the second connector 22 are two vertically arranged rectangular blocks arranged vertically up and down to form a T-shaped connector, the upper rectangular block is 58 cm long, 38 cm wide, and 5 cm high; the lower rectangular block is 38 cm long, 20 cm wide, and 9 cm high. The two T-shaped connectors are symmetrically arranged to form the I-shaped connector 2, and the four corners of the first connector 21 and the second connector 22 are chamfered.

[0052] Furthermore, the fixing member is a triangular bolt 7, and the first connecting member 21 and the second connecting member 22 are connected by the triangular bolt 7 and the matching hexagonal nut to form the I-shaped connecting member 2. As a preferred embodiment, the triangular bolt 7 is an anti-theft bolt with an outer circle and an inner triangle structure, which requires a specific matching triangular key to open, to prevent ordinary tools from opening it at will, resulting in the loss of the cable. It is worth noting that in the track engineering, the same type of triangular bolt 7 is used in a specific structure, so that this type of bolt is universal in the construction of the track engineering, and internal staff can use specific tools to carry out structural maintenance, replace parts and other projects, simplifying the workload of workers and ensuring the work efficiency of workers.

[0053] Furthermore, the two ends of the fixing member are sunk into the connecting holes 23 of the first connecting member 21 and the second connecting member 22 to avoid the two ends of the fixing member being exposed to the outside, which ensures the flatness of the installation of the cover body 1 on the one hand, and on the other hand, avoids the two ends of the fixing member being outside, which makes it easy to open the fixing member and causes the loss of the internal cables. It is worth noting that the connecting holes 23 on the first connecting member 21 and the second connecting member 22 match the properties of the triangular bolt 7. The first connecting member 21 is provided with a circular stepped through hole, so that the head of the triangular bolt 7 is sunk into the hole; the second connecting member 22 is provided with a stepped through hole that is a combination of a regular hexagon and a circle, so that the hexagonal nut is sunk into the hole.

[0054] Furthermore, the positioning grooves 6 corresponding to the two adjacent cover bodies 1 are respectively clamped in the grooves 4 on both sides of the I-shaped connector 2, and the size of the I-shaped connector 2 matches the size of the groove 4, ensuring that the I-shaped connector 2 can stably connect each cover body 1.

[0055] Furthermore, the four corners of the cover body 1 are chamfered, and the size of the chamfer is 4 cm.

[0056] Furthermore, the thickness of the cover body 1 is 2-3 cm, preferably 2.5 cm.

[0057] A method for preparing a flexible fiber concrete cover plate for a cable trench comprises the following steps:

[0058] S1. Weigh 150 parts of cement, 170 parts of water, 280 parts of river sand, 70 parts of fine stone, 25 parts of polypropylene fiber, 15 parts of polyacrylamide, 20 parts of polyurethane elastomer particles, 18 parts of hydrophobically modified polyacrylate copolymer emulsion, 40 parts of expansion agent, 15 parts of air entraining agent, and 25 parts of polyacrylate;

[0059] S2. The polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are mixed and set aside;

[0060] S3. After the cement, water, river sand, fine stone, polyacrylamide, expansion agent, air entraining agent and polyacrylic acid salt are mixed and stirred evenly, the evenly mixed polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylic acid ester copolymer emulsion are added, and then dispersed evenly to obtain concrete slurry.

[0061] S4. Pour the concrete slurry into the cover plate mold, demould it after curing, and obtain the flexible fiber concrete cover plate, wherein the curing comprises the following steps:

[0062] S41. After the concrete has initially set, water is sprinkled on its surface and covered with an insulation film for 5 days;

[0063] S42. Remove the thermal insulation film and store water in the concrete for 10 days for curing.

[0064] Example 2

[0065] The flexible fiber concrete cover plate for a cable trench prepared in this embodiment has the same structure and size as those in Embodiment 1.

[0066] A method for preparing a flexible fiber concrete cover plate for a cable trench comprises the following steps:

[0067] S1. Weigh 180 parts of cement, 200 parts of water, 300 parts of river sand, 70 parts of fine stone, 30 parts of polypropylene fiber, 10 parts of polyacrylamide, 15 parts of polyurethane elastomer particles, 18 parts of hydrophobically modified polyacrylate copolymer emulsion, 45 parts of expansion agent, 20 parts of air entraining agent, and 18 parts of polyacrylate;

[0068] S2. The polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are uniformly mixed for use;

[0069] S3. After the cement, water, river sand, fine stone, polyacrylamide, expansion agent, air entraining agent and polyacrylic acid salt are mixed and stirred evenly, the evenly mixed polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylic acid ester copolymer emulsion are added, and then dispersed evenly to obtain concrete slurry.

[0070] S4. Pour the concrete slurry into the cover plate mold, demould it after curing, and obtain the flexible fiber concrete cover plate, wherein the curing comprises the following steps:

[0071] S41. After the concrete has initially set, water is sprinkled on its surface and covered with an insulation film for 4 days;

[0072] S42. Remove the thermal insulation film and store water in the concrete for 9 days for curing.

[0073] Comparative Example 1

[0074] Comparative Example 1 provides a flexible fiber concrete cover plate for a cable trench, the structure and dimensions of which are the same as those of Example 1.

[0075] A method for preparing a flexible fiber concrete cover plate for a cable trench is different from that of Example 1 in that the raw materials do not contain a hydrophobically modified polyacrylate copolymer emulsion, and during the preparation, step S2 is omitted, and the raw materials are directly mixed and stirred evenly.

[0076] Comparative Example 2

[0077] Comparative Example 2 provides a flexible fiber concrete cover for a cable trench, the structure and dimensions of which are the same as those of Example 1.

[0078] A method for preparing a flexible fiber concrete cover plate for a cable trench, which differs from Example 1 in that the raw material does not contain polyurethane elastomer particles. During the preparation, step S2 is: uniformly mixing the polypropylene fiber and the hydrophobically modified polyacrylate copolymer emulsion for standby use.

[0079] Comparative Example 3

[0080] Comparative Example 3 provides a flexible fiber concrete cover for a cable trench, the structure and dimensions of which are the same as those of Example 1.

[0081] A method for preparing a flexible fiber concrete cover plate for a cable trench is different from that of comparative example 1 in that the raw materials do not contain polyacrylamide, and the rest of the preparation methods are the same.

[0082] Comparative Example 4

[0083] Comparative Example 4 provides a flexible fiber concrete cover for a cable trench, the structure and dimensions of which are the same as those of Example 1.

[0084] A method for preparing a flexible fiber concrete cover plate for a cable trench is different from that in Example 1 in that the raw materials do not contain polyacrylate, and the rest of the preparation methods are the same.

[0085] Performance Test:

[0086] There is a lack of relevant specifications for the performance indicators of current concrete cover plates. The present invention does not test the prepared flexible fiber concrete cover plates, but tests concrete specimens cast with the raw materials of the cover plates in various embodiments and comparative examples according to relevant standards, and the performance of the specimens reflects the performance of the cover plates.

[0087] The reference standards and methods are as follows:

[0088] Flexural strength, compressive strength, splitting test: JTJ053-94 "Test Procedures for Cement Concrete in Highway Engineering"

[0089] Impact toughness: Drop weight impact method, use a steel ball to fall freely from a certain height to impact a steel ball placed in the center of the specimen. When a crack appears on the lower edge of the specimen, record the number of impacts, i.e. the number of initial crack impacts. Then continue the impact cycle until the crack in the specimen runs through the entire cross section, record the number of impacts again, i.e. the number of destructive impacts. The specimen size is 100mm×100mm×400mm.

[0090] The impact toughness of concrete is calculated as follows:

[0091] W=Nmgh

[0092] Where W is the impact toughness of concrete, Nm;

[0093] N——Number of impacts at the time of destruction;

[0094] m——weight of steel hammer, 4kg;

[0095] h——the drop height of the impact hammer, 0.4m;

[0096] g——9.80N / kg.

[0097] The test results are shown in Tables 1 and 2 below:

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102] It can be seen from Table 1 and Table 2 that, compared with the control example, the mechanical properties of the embodiment are improved to a certain extent. Compared with Comparative Examples 1 and 3, the crack resistance of the embodiment is significantly improved.

[0103] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A flexible fiber concrete cover plate, characterized in that: The invention comprises a plurality of cover plate bodies (1), wherein two adjacent cover plate bodies (1) are connected by an I-shaped connecting piece (2); the cover plate body (1) is a rectangular parallelepiped; a mounting groove (5) is provided in the middle of two long sides of the cover plate body (1); two pairs of positioning grooves (6) are symmetrically provided on the upper and lower surfaces of the two long sides of the cover plate body (1), and the two pairs of positioning grooves (6) are arranged at the same interval on both sides of the mounting groove (5); the adjacent two cover plate bodies (1) are connected to form a set of cover plates by the I-shaped connecting piece (2) and the positioning grooves (6); The raw materials of the cover plate include, by weight: 150-180 parts of cement, 170-220 parts of water, 250-300 parts of river sand, 50-100 parts of fine stone, 20-30 parts of polypropylene fiber, 10-15 parts of polyacrylamide, 15-25 parts of polyurethane elastomer particles, 18-20 parts of hydrophobically modified polyacrylate copolymer emulsion, 30-50 parts of expansion agent, 8-25 parts of air entraining agent, and 18-25 parts of polyacrylate; The method for preparing the flexible fiber concrete cover plate comprises the following steps: S1. Raw material ratio of flexible fiber concrete cover plate Weigh the required raw materials; S2. The polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are mixed and set aside; S3. The cement, water, river sand, fine stone, polyacrylamide, expansion agent, air entraining agent and polyacrylic acid salt are mixed and stirred uniformly, and then the polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are added and dispersed uniformly to obtain a concrete slurry; S4. Pour the concrete slurry into a cover plate mold, and demould it after curing to obtain the flexible fiber concrete cover plate.

2. A flexible fiber concrete cover plate according to claim 1, characterized in that: In parts by weight, the raw materials of the cover plate include: 150-160 parts of cement, 170-190 parts of water, 250-290 parts of river sand, 70-90 parts of fine stone, 25 parts of polypropylene fiber, 15 parts of polyacrylamide, 20 parts of polyurethane elastomer particles, 18 parts of hydrophobically modified polyacrylate copolymer emulsion, 40 parts of expansion agent, 15 parts of air entraining agent, and 25 parts of polyacrylate.

3. The flexible fiber concrete cover plate according to claim 1, characterized in that: The polyacrylate is prepared by compounding sodium polyacrylate and calcium polyacrylate in a molar ratio of 1:

1.

4. The flexible fiber concrete cover plate according to claim 1, characterized in that: The particle size of the fine stone is 8-10 mm.

5. The flexible fiber concrete cover plate according to claim 1, characterized in that: The polypropylene fiber is a monofilament fiber with a length of 20-25 mm, a diameter of 40-50 μm, a density of 850-900 kg / m 3 , an elastic modulus of 3-3.8 GPa, a tensile strength of 300-600 MPa, and a breaking elongation of 15-35%.

6. The flexible fiber concrete cover plate according to claim 1, characterized in that: The particle size of the polyurethane elastomer particles is 0.01-0.05 mm.

7. A method for preparing a flexible fiber concrete cover plate, characterized in that: The following steps are involved: S1. Weigh the required raw materials according to the raw material ratio of a flexible fiber concrete cover plate according to any one of claims 1 to 6; S2. The polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are mixed and set aside; S3. The cement, water, river sand, fine stone, polyacrylamide, expansion agent, air entraining agent and polyacrylic acid salt are mixed and stirred uniformly, and then the polypropylene fiber, polyurethane elastomer particles and hydrophobically modified polyacrylate copolymer emulsion are added and dispersed uniformly to obtain a concrete slurry; S4. Pour the concrete slurry into a cover plate mold, and demould it after curing to obtain the flexible fiber concrete cover plate.

8. The method for preparing a flexible fiber concrete cover plate according to claim 7, characterized in that: In step S4, the maintenance includes the following steps: S41. After the concrete has initially set, sprinkle water on its surface and cover it with an insulation film for 4-5 days; S42. Remove the thermal insulation film and store water in the concrete for curing for 9-10 days.

9. Application of a flexible fiber concrete cover plate as claimed in any one of claims 1 to 6 in construction projects.

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