High-strength RPC cover plate and preparation method thereof

Abstract

The invention discloses a high-strength RPC cover plate and a preparation method thereof, and relates to the technical field of building materials, the RPC cover plate comprises the following raw materials by weight: 100-200 parts of cement; 50 to 100 parts of a modified mineral admixture; 200 to 400 parts of a modified aggregate / fiber compound; 10 to 20 parts of modified carboxylic butadiene-styrene latex; 10 to 50 parts of crushed stone; 10-30 parts of reinforcing steel bars or steel wires; 1-5 parts of an additive; 100 to 300 parts of water; the preparation method comprises the following steps: carrying out dry mixing on dry materials, sequentially adding the admixture, water, the modified carboxylic butadiene-styrene latex and the crushed stone pieces, putting into a mold, vibrating, putting reinforcing steel bars or steel wires, and continuously vibrating; flattening the surface, and covering with a film; and demolding, dry curing and watering are conducted, and the high-strength RPC cover plate is obtained. The RPC cover plate has the beneficial effects that the prepared RPC cover plate has excellent compressive strength and breaking strength, and also has excellent heat insulation, heat resistance, corrosion resistance and wear resistance.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a high-strength RPC cover plate and a preparation method thereof. Background Art

[0002] Reactive Powder Concrete (RPC) is a cement-based material with ultra-high strength, high durability, high toughness and good volume stability developed in the mid-1990s by using conventional cement and other materials, following high-strength and high-performance concrete. It is a high-performance concrete composed of DSP materials and fiber-reinforced materials.

[0003] As a high-tech concrete, the performance of RPC material has made a qualitative leap compared with ordinary concrete and existing high-performance concrete, and it is superior to steel in terms of economy and environmental protection. RPC cover can effectively reduce the deadweight of the structure. Due to the characteristics of RPC cover, the thickness of the interface transition zone can be reduced. The reduction of aggregate particle size reduces the probability of defects in itself and the defects of the entire matrix. RPC is very dense and has extremely low porosity. It can not only prevent radioactive substances from leaking from the inside, but also resist corrosion from external corrosive media, which improves the uniformity, strength and durability of the system as a whole. At the same time, the amount of stirrups and force bars is reduced, and even stirrups are not required. At the same time, maintenance costs are reduced or eliminated, and the service life is extended, so it has a high performance-price ratio.

[0004] However, with the increasing development of science and technology and economy, higher requirements are placed on the strength of RPC covers. For example, when used in roads, railways, water conservancy and hydropower, bridges, tunnels, subways and other facilities, RPC covers need to withstand greater pressure and impact. Therefore, it is necessary to improve the strength of RPC covers to meet the growing needs. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a high-strength RPC cover plate and a preparation method thereof.

[0006] The technical solution of the present invention is as follows: A first aspect of the present invention provides a high-strength RPC cover plate, comprising the following raw materials in parts by weight: 100~200 parts of cement; 50~100 parts of modified mineral admixture; Modified aggregate / fiber composite 200~400 parts; 10-20 parts of modified carboxyl styrene butadiene latex; 10~50 pieces of crushed stone; 10~30 pieces of steel bars or steel wires; 1~5 parts of admixture; 100~300 parts of water.

[0007] Optionally, the preparation method of the modified mineral admixture comprises: adding potassium tetratitanate whiskers to slag powder and mixing them uniformly to obtain a mixture; The mixture is heated to 50-60° C., and nitric acid is added while stirring; then the temperature is raised to 70-80° C., reacted for 30-60 minutes, and dried to obtain a product; Adding silane coupling agent to the product and mixing evenly; adding microsilica powder and dispersing by ultrasonication; The mixed material is dried and crushed to obtain a modified mineral admixture.

[0008] Optionally, in the method for preparing the modified mineral admixture, The mass ratio of slag powder, potassium tetratitanate whisker and microsilicon powder is 8~10:0.5~1.5:3~4; The amount of nitric acid added is 4-6% of the total mass of slag powder and potassium titanate whiskers, and the concentration of nitric acid is 70-75%; The addition amount of silane coupling agent KH550 is 1-2% of the total mass of slag powder, potassium titanate whisker and microsilica powder.

[0009] Optionally, the method for preparing the modified aggregate / fiber composite comprises: Add steel fiber to silane coupling agent and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is first heated to 300-400°C and kept warm for 0.5-1h; then heated to 600-700°C and kept warm for 0.5-1h; then quickly cooled to 300-400°C and kept warm for 0.5-1h; finally quickly cooled to 100-200°C and kept warm for 0.5-1h; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

[0010] Optionally, in the method for preparing the modified aggregate / fiber composite, The mass ratio of steel fiber, kaolin and quartz sand is 1~2:3~4:8~10; The amount of silane coupling agent added is 1% to 2% of the total mass of steel fiber, kaolin and quartz sand; The holding time is 0.5~1h, the heating rate is 1~4℃ / min, and the cooling rate is 8~12℃ / min.

[0011] Optionally, the preparation method of the modified carboxylated styrene-butadiene latex comprises: Dispersing nano calcium carbonate and sodium stearate in water to form a dispersion; Dispersing polypropylene fiber in ethanol, adding silane coupling agent, and mixing evenly; adding the dispersion, heating at 80-100° C. for reaction for 1-2 hours, cooling, filtering to obtain a solid product, and drying to obtain a product; The product is added into carboxylated styrene butadiene latex, and mixed evenly to obtain modified carboxylated styrene butadiene latex.

[0012] Optionally, in the method for preparing the modified carboxylated styrene-butadiene latex, The mass ratio of nano calcium carbonate, polypropylene fiber and carboxyl styrene butadiene latex is 0.8~1.2:1~1.6:3~4; The amount of sodium stearate added is 1%~2% of the mass of nano calcium carbonate; The added amount of silane coupling agent is 1% to 2% of the total mass of nano-calcium carbonate and polypropylene fiber.

[0013] Optionally, it is characterized in that The powder content of the crushed stone pieces is below 1.0%, the crushing value is below 10%, and the average particle size is 5-10 mm, wherein the content of particles with a diameter below 5 mm does not exceed 5%, and the content of particles with a diameter above 10 mm does not exceed 10%.

[0014] A second aspect of the present invention provides a method for preparing the high-strength RPC cover plate, comprising the following steps: S1. dry mixing cement, modified mineral admixture and modified aggregate / fiber composite; S2, continue to add admixtures and water, and stir after adding; S3, continue to add modified carboxyl styrene butadiene latex, and stir after adding; S4, continue to add crushed stone pieces, stir after adding, and obtain a mixture; S5, adding the mixed material into a material placing machine; S5, loading the mixed material into the mold from the material placing machine, and vibrating the mold; S6, continue to put steel bars or steel wires into the mixture, and continue to vibrate the mold; S7, smoothing the surface of the mixture and coating it; S8, separating the initially solidified RPC cover plate from the mold to obtain a demoulded RPC cover plate; S9, dry-curing the RPC cover plate and sprinkling water to obtain a high-strength RPC cover plate.

[0015] Optionally, in step S1, the dry mixing time is 30s-1min; In step S2, the stirring time is 3-4 minutes; In step S3, the stirring time is 1 to 3 minutes; In step S4, the stirring time is 2 to 3 minutes; In step S5, the time of vibrating the mold is 20 to 40 seconds; In step S6, the time of vibrating the mold is 5 to 15 seconds; In step S8, the initially solidified RPC cover plate is separated from the mold after 18 to 22 hours; In step S9, the RPC cover is dry-cured for 6 to 9 days and then watered.

[0016] The present invention has at least one of the following beneficial effects: 1. The RPC cover plate prepared by the present invention has excellent compressive strength and flexural strength, and also has excellent heat insulation, heat resistance, corrosion resistance and wear resistance.

[0017] 2. The present invention can improve the compressive strength, flexural strength, thermal insulation, heat resistance, corrosion resistance and wear resistance of the RPC cover plate by adding the modified slag powder / microsilicon powder / potassium titanate whisker composite material. On the one hand, since the particle size of microsilica powder is very small and easy to agglomerate, the present invention processes slag powder and potassium tetratitanate whiskers to form porous surfaces of the slag powder and potassium tetratitanate whiskers, so that the microsilica powder can be embedded in the porous surfaces of the slag powder and potassium tetratitanate whiskers to reduce the agglomeration of the microsilica powder; and the slag powder and potassium tetratitanate whiskers are modified by a silane coupling agent to improve the compatibility between the microsilica powder and the slag powder and potassium tetratitanate whiskers; on the other hand, potassium tetratitanate whiskers are a high-performance reinforcing fiber, and mixing them with microsilica powder and slag powder can not only reduce their agglomeration and improve their dispersibility, but also the potassium tetratitanate whiskers have high mechanical strength and excellent thermal insulation, heat resistance, corrosion resistance and wear resistance. The combined action of potassium tetratitanate whiskers, slag powder and microsilica powder can improve the mechanical strength, high temperature resistance, corrosion resistance and wear resistance of the RPC cover plate.

[0018] 3. On the one hand, the present invention can improve the dispersibility of steel fibers by mixing kaolin with aggregates and steel fibers, so that the steel fibers can be evenly dispersed in the system, which plays a role in improving the compressive strength and flexural strength of the material system; on the other hand, by calcining kaolin, aggregates and steel fibers, not only can kaolin be transformed into metakaolin, but metakaolin can significantly improve the mechanical strength and durability of the RPC cover; and by calcining the aggregates and steel fibers, the mechanical strength, weather resistance and durability can be improved; and by first adopting gradient heating and slow heating, it is helpful to avoid the problem of cracks or cracks in the aggregates and steel fibers caused by sudden temperature changes and internal stress; and then adopting gradient cooling and rapid cooling, it is helpful to transform kaolin into metakaolin, so that metakaolin is evenly mixed with aggregates and steel fibers, and the three together can improve the mechanical strength, high temperature resistance, corrosion resistance and wear resistance of the RPC cover. .

[0019] 4. The modified carboxylated styrene butadiene latex of the present invention can further improve the compressive strength and flexural strength of the RPC cover. On the one hand, the carboxylated styrene butadiene latex can improve the compressive, flexural, tensile strength and other properties of the RPC cover, and at the same time improve the impermeability of concrete, reduce cracks, and extend the service life; nano-calcium carbonate can improve the compressive strength, flexural strength, freeze-thaw cycle resistance and carbonization resistance of the RPC cover, and polypropylene fiber can improve the flexural and tensile strength; on the other hand, the polypropylene fiber, nano-calcium carbonate and carboxylated styrene butadiene latex of the present invention can form a network structure through modification, thereby improving the compressive strength and flexural strength of the RPC cover. The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and to provide a high-strength RPC cover and a preparation method thereof.

[0020] The technical solution of the present invention is as follows: A first aspect of the present invention provides a high-strength RPC cover plate, comprising the following raw materials in parts by weight: 100~200 parts of cement; 50~100 parts of modified mineral admixture; Modified aggregate / fiber composite 200~400 parts; 10-20 parts of modified carboxyl styrene butadiene latex; 10~50 pieces of crushed stone; 10~30 pieces of steel bars or steel wires; 1~5 parts of admixture; 100~300 parts of water.

[0021] Optionally, the preparation method of the modified mineral admixture comprises: adding potassium tetratitanate whiskers to slag powder and mixing them uniformly to obtain a mixture; The mixture is heated to 50-60° C., and nitric acid is added while stirring; then the temperature is raised to 70-80° C., reacted for 30-60 minutes, and dried to obtain a product; Adding silane coupling agent to the product and mixing evenly; adding microsilica powder and dispersing by ultrasonication; The mixed material is dried and crushed to obtain a modified mineral admixture.

[0022] Optionally, in the method for preparing the modified mineral admixture, The mass ratio of slag powder, potassium tetratitanate whisker and microsilicon powder is 8~10:0.5~1.5:3~4; The amount of nitric acid added is 4-6% of the total mass of slag powder and potassium titanate whiskers, and the concentration of nitric acid is 70-75%; The addition amount of silane coupling agent KH550 is 1-2% of the total mass of slag powder, potassium titanate whisker and microsilica powder.

[0023] Optionally, the method for preparing the modified aggregate / fiber composite comprises: Add steel fiber to silane coupling agent and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is first heated to 300-400°C and kept warm for 0.5-1h; then heated to 600-700°C and kept warm for 0.5-1h; then quickly cooled to 300-400°C and kept warm for 0.5-1h; finally quickly cooled to 100-200°C and kept warm for 0.5-1h; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

[0024] Optionally, in the method for preparing the modified aggregate / fiber composite, The mass ratio of steel fiber, kaolin and quartz sand is 1~2:3~4:8~10; The amount of silane coupling agent added is 1% to 2% of the total mass of steel fiber, kaolin and quartz sand; The holding time is 0.5~1h, the heating rate is 1~4℃ / min, and the cooling rate is 8~12℃ / min.

[0025] Optionally, the preparation method of the modified carboxylated styrene-butadiene latex comprises: Dispersing nano calcium carbonate and sodium stearate in water to form a dispersion; Dispersing polypropylene fiber in ethanol, adding silane coupling agent, and mixing evenly; adding the dispersion, heating at 80-100° C. for reaction for 1-2 hours, cooling, filtering to obtain a solid product, and drying to obtain a product; The product is added into carboxylated styrene butadiene latex, and mixed evenly to obtain modified carboxylated styrene butadiene latex.

[0026] Optionally, in the method for preparing the modified carboxylated styrene-butadiene latex, The mass ratio of nano calcium carbonate, polypropylene fiber and carboxyl styrene butadiene latex is 0.8~1.2:1~1.6:3~4; The amount of sodium stearate added is 1%~2% of the mass of nano calcium carbonate; The added amount of silane coupling agent is 1% to 2% of the total mass of nano-calcium carbonate and polypropylene fiber.

[0027] Optionally, it is characterized in that The powder content of the crushed stone pieces is below 1.0%, the crushing value is below 10%, and the average particle size is 5-10 mm, wherein the content of particles with a diameter below 5 mm does not exceed 5%, and the content of particles with a diameter above 10 mm does not exceed 10%.

[0028] A second aspect of the present invention provides a method for preparing the high-strength RPC cover plate, comprising the following steps: S1. dry mixing cement, modified mineral admixture and modified aggregate / fiber composite; S2, continue to add admixtures and water, and stir after adding; S3, continue to add modified carboxyl styrene butadiene latex, and stir after adding; S4, continue to add crushed stone pieces, stir after adding, and obtain a mixture; S5, adding the mixed material into a material placing machine; S5, loading the mixed material into the mold from the material placing machine, and vibrating the mold; S6, continue to put steel bars or steel wires into the mixture, and continue to vibrate the mold; S7, smoothing the surface of the mixture and coating it; S8, separating the initially solidified RPC cover plate from the mold to obtain a demoulded RPC cover plate; S9, dry-curing the RPC cover plate and sprinkling water to obtain a high-strength RPC cover plate.

[0029] Optionally, in step S1, the dry mixing time is 30s-1min; In step S2, the stirring time is 3-4 minutes; In step S3, the stirring time is 1 to 3 minutes; In step S4, the stirring time is 2 to 3 minutes; In step S5, the time of vibrating the mold is 20 to 40 seconds; In step S6, the time of vibrating the mold is 5 to 15 seconds; In step S8, the initially solidified RPC cover plate is separated from the mold after 18 to 22 hours; In step S9, the RPC cover is dry-cured for 6 to 9 days and then watered.

[0030] The present invention has at least one of the following beneficial effects: 1. The RPC cover plate prepared by the present invention has excellent compressive strength and flexural strength, and also has excellent heat insulation, heat resistance, corrosion resistance and wear resistance.

[0031] 2. The present invention can improve the compressive strength, flexural strength, thermal insulation, heat resistance, corrosion resistance and wear resistance of the RPC cover plate by adding the modified slag powder / microsilicon powder / potassium titanate whisker composite material. On the one hand, since the particle size of microsilica powder is very small and easy to agglomerate, the present invention processes slag powder and potassium tetratitanate whiskers to form porous surfaces of the slag powder and potassium tetratitanate whiskers, so that the microsilica powder can be embedded in the porous surfaces of the slag powder and potassium tetratitanate whiskers to reduce the agglomeration of the microsilica powder; and the slag powder and potassium tetratitanate whiskers are modified by a silane coupling agent to improve the compatibility between the microsilica powder and the slag powder and potassium tetratitanate whiskers; on the other hand, potassium tetratitanate whiskers are a high-performance reinforcing fiber, and mixing them with microsilica powder and slag powder can not only reduce their agglomeration and improve their dispersibility, but also the potassium tetratitanate whiskers have high mechanical strength and excellent thermal insulation, heat resistance, corrosion resistance and wear resistance. The combined action of potassium tetratitanate whiskers, slag powder and microsilica powder can improve the mechanical strength, high temperature resistance, corrosion resistance and wear resistance of the RPC cover plate.

[0032] 3. On the one hand, the present invention can improve the dispersibility of steel fibers by mixing kaolin with aggregates and steel fibers, so that the steel fibers can be evenly dispersed in the system, which plays a role in improving the compressive strength and flexural strength of the material system; on the other hand, by calcining kaolin, aggregates and steel fibers, not only can kaolin be transformed into metakaolin, but metakaolin can significantly improve the mechanical strength and durability of the RPC cover; and by calcining the aggregates and steel fibers, the mechanical strength, weather resistance and durability can be improved; and by first adopting gradient heating and slow heating, it is helpful to avoid the problem of cracks or cracks in the aggregates and steel fibers caused by sudden temperature changes and internal stress; and then adopting gradient cooling and rapid cooling, it is helpful to transform kaolin into metakaolin, so that metakaolin is evenly mixed with aggregates and steel fibers, and the three together can improve the mechanical strength, high temperature resistance, corrosion resistance and wear resistance of the RPC cover. .

[0033] 4. The modified carboxylated styrene butadiene latex of the present invention can further improve the compressive strength and flexural strength of the RPC cover plate. On the one hand, the carboxylated styrene butadiene latex can improve the compressive, flexural and tensile strength of the RPC cover plate, and at the same time improve the impermeability of concrete, reduce cracks and extend the service life; nano-calcium carbonate can improve the compressive strength, flexural strength, freeze-thaw cycle resistance and carbonization resistance of the RPC cover plate, and the polypropylene fiber can improve the flexural and tensile strength; on the other hand, the polypropylene fiber, nano-calcium carbonate and carboxylated styrene butadiene latex of the present invention can form a network structure through modification, thereby improving the compressive strength and flexural strength of the RPC cover plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a production flow chart of the RPC cover plate in Example 1. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] An embodiment of the present invention provides a high-strength RPC cover plate, comprising the following raw materials in parts by weight: 100~200 parts of cement; 50~100 parts of modified mineral admixture; Modified aggregate / fiber composite 200~400 parts; 10-20 parts of modified carboxyl styrene butadiene latex; 10~50 pieces of crushed stone; 10~30 pieces of steel bars or steel wires; 1~5 parts of admixture; 100~300 parts of water.

[0037] In some embodiments, the following raw materials are included in weight: 120~180 parts of cement; 60~90 parts of modified mineral admixture; 250~350 parts of modified aggregate / fiber composite; 12-18 parts of modified carboxyl styrene butadiene latex; 20-40 pieces of crushed stone; 15~25 pieces of steel bars or steel wires; 2~4 parts of admixture; 100~300 parts of water.

[0038] In some embodiments, the following raw materials are included in weight: 140~160 parts of cement; 70~80 parts of modified mineral admixture; Modified aggregate / fiber composite 280-320 parts; 14-16 parts of modified carboxyl styrene butadiene latex; 25-35 pieces of crushed stone; 18~22 pieces of steel bars or steel wires; 2.5~3.5 parts of admixture; 100~300 parts of water.

[0039] In some embodiments, the admixture is a water reducing agent.

[0040] Another embodiment of the present invention provides a method for preparing a high-strength RPC cover plate, comprising the following steps: 1. Ratio: Weigh according to the proportion. When the weight of the dry mix is ​​adjusted, other raw materials are adjusted in the same proportion. When the state of the mix changes during production, the water-binder ratio is adjusted according to ±0.005, and the water reducer dosage is adjusted according to ±0.1%.

[0041] 2. Mixing process: Put the dry mix (cement, modified mineral admixture and modified aggregate / fiber composite) into the mixer and dry mix for 30s-1min. Then add the admixture and water mixture weighed in advance in the mixer all at once and stir for 3-4min. Add the manually weighed modified carboxylated styrene-butadiene latex and continue stirring for 1-3min. After that, add the crushed stone chips weighed in advance in the mixer and stir for 2-3min.

[0042] 3. Molding process: The mixer discharges the material into the material distributor, and the mold is prepared. The material distributor discharges and loads the mold. The material that is clumped on the cover plate should be picked out in time. After the discharge is completed, vibrate for 20-30 seconds to level the mixture in the mold. The mold that is not full should be refilled with material, and steel bars or steel wires should be put in. Continue to vibrate for 5-15 seconds, and the steel bars should not be exposed. After the vibration is completed, the surface is smoothed, and the mold filled with materials is moved away from the operating table and coated in time.

[0043] 4. Demolding and curing process: After 18-22 hours, the RPC cover that has been initially set is separated from the mold. The mold can be demoulded by turning it upside down. After demoulding, the RPC cover is placed sideways (wide side) and tilted. It cannot be stacked up and down. Dry curing is done for 6-9 days and then watering is done. The RPC cover should be stored in a cool place and packaged after cooling.

[0044] 5. Packing and stacking: The produced cover boards are stacked separately according to the model, grade and production date. When packing, a layer of bubble film / EPM should be added between the boards to prevent the boards from direct contact and scratching. No more than 20 pieces of 2.5cm thick cover boards are packed per bundle, and no more than 10 pieces of 5cm thick cover boards are packed per bundle. The packed cover boards should be placed sideways (wide side), and the number of stacked layers should not exceed 3, and the layers should be separated by bubble film / EPM.

[0045] In some embodiments, the melon seed flakes (crushed stone flakes) used for production should strictly control the powder content to be below 1.0%, the crushing value to be below 10%, and the average particle size to be 5-10 mm, among which the content of particles below 5 mm shall not exceed 5%, and the content of particles above 10 mm shall not exceed 10%. It is advisable to use stones with better particle shape and less needle-like content; In some embodiments, the template should be cleaned and no cement slurry should adhere to the inside of the template. After cleaning with oxalic acid, rinse with clean water. During molding, the inside of the template should be dry and free of water, dust and debris. The mold should be stored in a cool place and not exposed to direct sunlight. In some embodiments, the vibration time is strictly controlled to 25±5s, depending on the working state of the mixture, and no over-vibration or under-vibration is allowed; In some embodiments, the RPC cover sheet should be coated immediately after forming, and the film surface should remain wet before demolding; In some embodiments, the time from discharging materials from the mixer to the completion of the vibration and finishing of the cover plate mold shall not exceed 20 minutes; In some embodiments, the trench cover should be demoulded 20±2 hours after molding, and demoulding should not be done earlier; In some embodiments, the demoulded cover board can be stacked in a cool place and must not be exposed to water before 7 days to prevent alkali blooming on the surface. After 7 days, it can be watered for curing; The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0046] The preparation methods of the modified mineral admixture, modified aggregate / fiber composite and modified carboxylated styrene-butadiene latex used in the following examples are as follows: (1) A method for preparing a modified mineral admixture comprises the following steps: adding potassium tetratitanate whiskers to slag powder and mixing them uniformly to obtain a mixture; The mixture was heated to 55° C., and nitric acid was added while stirring; then the temperature was raised to 75° C., reacted for 40 minutes, and dried to obtain a product; Add silane coupling agent KH550 to the product and mix well; continue to add microsilica powder and disperse by ultrasonic; The mixed material is dried and crushed to obtain a modified mineral admixture.

[0047] Among them, the mass ratio of slag powder, potassium tetratitanate whiskers and microsilica powder is 9:1:3.5; The amount of nitric acid added is 5% of the total mass of slag powder and potassium titanate whiskers, and the concentration of nitric acid is 70%; The addition amount of silane coupling agent KH550 is 1.5% of the total mass of slag powder, potassium titanate whisker and microsilica powder.

[0048] (2) Modifying the aggregate / fiber composite, comprising the following steps: Add steel fiber to silane coupling agent KH550 and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is first heated to 350°C at 1°C / min and kept warm for 0.5h; then heated to 650°C at 3°C / min and kept warm for 1h; then quickly cooled to 350°C at 8°C / min and kept warm for 0.5h; finally, quickly cooled to 150°C at 10°C / min and kept warm for 0.5h; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

[0049] Among them, the mass ratio of steel fiber, kaolin and quartz sand is 1:3.5:9; The addition amount of silane coupling agent KH550 is 1.5% of the total mass of steel fiber, kaolin and quartz sand.

[0050] (3) A method for preparing modified carboxylated styrene-butadiene latex, comprising the following steps: Dispersing nano calcium carbonate and sodium stearate in water to form a dispersion; Disperse polypropylene fiber in ethanol, continue to add silane coupling agent KH550, mix evenly; add the dispersion, heat at 90° C. for reaction for 1.5 hours, cool, filter to obtain a solid product, and dry to obtain a product; The product is added into carboxylated styrene butadiene latex, and mixed evenly to obtain modified carboxylated styrene butadiene latex.

[0051] Among them, the mass ratio of nano calcium carbonate, polypropylene fiber and carboxylated styrene butadiene latex is 1:1.2:3.5; The amount of sodium stearate added is 1% of the mass of nano calcium carbonate; The addition amount of silane coupling agent KH550 is 2% of the total mass of nano calcium carbonate and polypropylene fiber. Example 1

[0052] like Figure 1 As shown, this embodiment provides a method for preparing a high-strength RPC cover plate, comprising the following steps: 1. Ratio: Weigh according to the ratio, where 1 portion is 0.1kg: 100 parts of silicate 425 cement; 50 parts of modified mineral admixture; 200 parts of modified aggregate / fiber composite; 10 parts of modified carboxyl styrene butadiene latex; 10 pieces of crushed stone; 10 pieces of steel bars; 2 parts of water reducing agent YLD-JSSFT; 100 parts of water.

[0053] 2. Mixing process: Put the dry mix (cement, modified mineral admixture and modified aggregate / fiber composite) into the mixer and dry mix for 30 seconds. Then add the admixture and water mixture weighed in advance in the mixer all at once and stir for 3 minutes. Add the manually weighed modified carboxylated styrene-butadiene latex and continue stirring for 1 minute. After that, add the crushed stone chips weighed in advance in the mixer and stir for 2 minutes.

[0054] 3. Molding process: The mixer discharges the material into the material distributor, and the mold is prepared. The material distributor discharges and loads the mold. The material that is clumped on the cover plate should be picked out in time. After the discharge is completed, vibrate for 30 seconds to level the mixture in the mold. The mold that is not full should be refilled with material, and steel bars or steel wires should be put in. Continue to vibrate for 10 seconds, and the steel bars should not be exposed. After the vibration is completed, the surface is smoothed, and the mold filled with materials is moved away from the operating table and coated in time.

[0055] 4. Demolding and curing process: After 20 hours, the RPC cover that has been initially set is separated from the mold. The mold can be demoulded by turning it upside down. After demoulding, the RPC cover is placed on its side (wide side) and tilted. It must not be stacked up and down. Dry-cured for 7 days and then sprinkled with water. The RPC cover should be stored in a cool place and packaged after cooling.

[0056] 5. Packing and stacking: The produced cover boards are stacked separately according to the model, grade and production date. When packing, a layer of bubble film / EPM should be added between the boards to prevent the boards from direct contact and scratching. No more than 20 pieces of 2.5cm thick cover boards are packed per bundle, and no more than 10 pieces of 5cm thick cover boards are packed per bundle. The packed cover boards should be placed sideways (wide side), and the number of stacked layers should not exceed 3, and the layers should be separated by bubble film / EPM. Example 2

[0057] This embodiment provides a method for preparing a high-strength RPC cover plate, comprising the following steps: 1. Ratio: Weigh according to the ratio, where 1 portion is 0.1kg: 150 parts of silicate 425 cement; 75 parts of modified mineral admixture; 300 parts of modified aggregate / fiber composite; 15 parts of modified carboxyl styrene butadiene latex; 25 pieces of crushed stone; 20 pieces of steel bars; 3 parts of water reducing agent YLD-JSSFT; 200 parts of water.

[0058] 2. Mixing process: Put the dry mix (cement, modified mineral admixture and modified aggregate / fiber composite) into the mixer and dry mix for 40 seconds. Then add the admixture and water mixture weighed in advance in the mixer at one time and stir for 3.5 minutes. Add the manually weighed modified carboxylated styrene-butadiene latex and continue stirring for 2 minutes. After that, add the crushed stone chips weighed in advance in the mixer and stir for 2.5 minutes.

[0059] 3. Molding process: The mixer discharges the material into the material distributor, and the mold is prepared. The material distributor discharges and loads the mold. The material that is clumped on the cover plate should be picked out in time. After the discharge is completed, vibrate for 30 seconds to level the mixture in the mold. The mold that is not full should be refilled with material, and steel bars or steel wires should be put in. Continue to vibrate for 10 seconds, and the steel bars should not be exposed. After the vibration is completed, the surface is smoothed, and the mold filled with materials is moved away from the operating table and coated in time.

[0060] 4. Demolding and curing process: After 20 hours, the RPC cover that has been initially set is separated from the mold. The mold can be demoulded by turning it upside down. After demoulding, the RPC cover is placed on its side (wide side) and tilted. It must not be stacked up and down. Dry-cured for 7 days and then sprinkled with water. The RPC cover should be stored in a cool place and packaged after cooling.

[0061] 5. Packing and stacking: The produced cover boards are stacked separately according to the model, grade and production date. When packing, a layer of bubble film / EPM should be added between the boards to prevent the boards from direct contact and scratching. No more than 20 pieces of 2.5cm thick cover boards are packed per bundle, and no more than 10 pieces of 5cm thick cover boards are packed per bundle. The packed cover boards should be placed sideways (wide side), and the number of stacked layers should not exceed 3, and the layers should be separated by bubble film / EPM. Example 3

[0062] This embodiment provides a method for preparing a high-strength RPC cover plate, comprising the following steps: 1. Ratio: Weigh according to the ratio, where 1 portion is 0.1kg: 200 parts of silicate 425 cement; 100 parts of modified mineral admixture; 400 parts of modified aggregate / fiber composite; 20 parts of modified carboxyl styrene butadiene latex; 50 pieces of crushed stone; 30 pieces of steel bars; Water reducing agent YLD-JSSFT 5 parts; 300 parts of water.

[0063] 2. Mixing process: Put the dry mix (cement, modified mineral admixture and modified aggregate / fiber composite) into the mixer and dry mix for 40 seconds. Then add the admixture and water mixture weighed in advance in the mixer at one time and stir for 3.5 minutes. Add the manually weighed modified carboxylated styrene-butadiene latex and continue stirring for 2 minutes. After that, add the crushed stone chips weighed in advance in the mixer and stir for 2.5 minutes.

[0064] 3. Molding process: The mixer discharges the material into the material distributor, and the mold is prepared. The material distributor discharges and loads the mold. The material that is clumped on the cover plate should be picked out in time. After the discharge is completed, vibrate for 30 seconds to level the mixture in the mold. The mold that is not full should be refilled with material, and steel bars or steel wires should be put in. Continue to vibrate for 10 seconds, and the steel bars should not be exposed. After the vibration is completed, the surface is smoothed, and the mold filled with materials is moved away from the operating table and coated in time.

[0065] 4. Demolding and curing process: After 20 hours, the RPC cover that has been initially set is separated from the mold. The mold can be demoulded by turning it upside down. After demoulding, the RPC cover is placed on its side (wide side) and tilted. It must not be stacked up and down. Dry-cured for 7 days and then sprinkled with water. The RPC cover should be stored in a cool place and packaged after cooling.

[0066] 5. Packing and stacking: The produced cover boards are stacked separately according to the model, grade and production date. When packing, a layer of bubble film / EPM should be added between the boards to prevent the boards from direct contact and scratching. No more than 20 pieces of 2.5cm thick cover boards are packed per bundle, and no more than 10 pieces of 5cm thick cover boards are packed per bundle. The packed cover boards should be placed sideways (wide side), and the number of stacked layers should not exceed 3, and the layers should be separated by bubble film / EPM. Comparative Example 1

[0067] The difference from Example 1 is that the "50 parts of modified mineral admixture" is changed to "40 parts of slag powder, 10 parts of microsilica powder", that is, no modified mineral admixture is added, but unmodified slag powder and microsilica powder are added instead.

[0068] The rest is the same as Example 1. Comparative Example 2

[0069] The difference from Example 1 is that "200 parts of modified aggregate / fiber composite" is changed to "180 parts of quartz sand and 20 parts of steel fiber", that is, no modified aggregate / fiber composite is added, but unmodified quartz sand and steel fiber are added instead.

[0070] The rest is the same as Example 1. Comparative Example 3

[0071] The difference from Example 1 is that the preparation method of the modified aggregate / fiber composite is changed to the following: Add steel fiber to silane coupling agent KH550 and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is first heated directly to 650°C at a rate of 3°C / min and kept at that temperature for 2 hours; then cooled to room temperature at a rate of 3°C / min; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

[0072] The rest is the same as Example 1. Comparative Example 4

[0073] The difference from Example 1 is that the preparation method of the modified aggregate / fiber composite is changed to the following: Add steel fiber to silane coupling agent KH550 and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is heated to 350°C at a rate of 3°C / min and kept warm for 0.5h; then heated to 650°C at a rate of 3°C / min and kept warm for 1h; then quickly cooled to 350°C at a rate of 8°C / min and kept warm for 0.5h; finally quickly cooled to 150°C at a rate of 8°C / min and kept warm for 0.5h; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

[0074] The rest is the same as Example 1. Comparative Example 5

[0075] The difference from Example 1 is that no modified carboxyl styrene butadiene latex is added, and the other steps are the same as Example 1. test

[0076] The performance of the RPC cover plates prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was tested, specifically according to the method in GB / T31387-2015.

[0077] The test results are shown in Table 1: Compressive strength / MPa Flexural strength / MPa Example 1 145 24.1 Example 2 158 31.3 Example 3 153 28.7 Comparative Example 1 121 15.7 Comparative Example 2 125 16.2 Comparative Example 3 128 16.8 Comparative Example 4 136 18.6 Comparative Example 5 118 14.5 It can be seen from Table 1 that the RPC cover plates prepared in Examples 1 to 3 have excellent compressive strength and flexural strength, with the compressive strength being above 140 MPa and the flexural strength being 20 MPa. Comparing Examples 1 to 3 with Comparative Examples 1 to 5, it can be seen that the compressive strength and flexural strength of the RPC cover plates prepared in Examples 1 to 3 are better than those in Comparative Example 1 (using unmodified slag powder and microsilica powder), indicating that whether the slag powder and microsilica powder are modified will affect the compressive strength and flexural strength of the RPC cover plates; the compressive strength and flexural strength of the RPC cover plates prepared in Examples 1 to 3 are better than those in Comparative Example 2 (using unmodified quartz sand and steel fiber), indicating that whether the quartz sand and steel fiber are modified will affect the compressive strength and flexural strength of the RPC cover plates; The compressive strength and flexural strength of the RPC cover plates prepared in Examples 1 to 3 are better than those in Comparative Example 3 (without gradient heating and cooling) and Comparative Document 4 (heating at the same rate and cooling at the same rate), indicating that whether gradient heating and cooling are adopted and the rate of gradient heating and cooling will affect the compressive strength and flexural strength of the RPC cover plates; the compressive strength and flexural strength of the RPC cover plates prepared in Examples 1 to 3 are better than those in Comparative Example 5 (without the addition of modified carboxylated styrene butadiene latex), indicating that whether the addition of modified carboxylated styrene butadiene latex will affect the compressive strength and flexural strength of the RPC cover plates.

[0078] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A high-strength RPC cover plate, characterized in that: The invention comprises the following raw materials in parts by weight: 100~200 parts of cement; 50~100 parts of modified mineral admixture; Modified aggregate / fiber composite 200~400 parts; 10-20 parts of modified carboxyl styrene butadiene latex; 10~50 pieces of crushed stone; 10~30 pieces of steel bars or steel wires; 1~5 parts of admixture; 100~300 parts of water.

2. The high-strength RPC cover plate according to claim 1 is characterized in that: The preparation method of the modified mineral admixture comprises: adding potassium tetratitanate whiskers to slag powder and mixing them uniformly to obtain a mixture; The mixture is heated to 50-60° C., and nitric acid is added while stirring; then the temperature is raised to 70-80° C., reacted for 30-60 minutes, and dried to obtain a product; Adding silane coupling agent to the product and mixing evenly; continuing to add microsilica powder and dispersing by ultrasonication; The mixed material is dried and crushed to obtain a modified mineral admixture.

3. The high-strength RPC cover plate according to claim 2 is characterized in that: In the preparation method of the modified mineral admixture, The mass ratio of slag powder, potassium tetratitanate whisker and microsilica powder is 8~10:0.5~1.5:3~4; The amount of nitric acid added is 4-6% of the total mass of slag powder and potassium titanate whiskers, and the concentration of nitric acid is 70-75%; The addition amount of silane coupling agent KH550 is 1-2% of the total mass of slag powder, potassium titanate whisker and microsilica powder.

4. The high-strength RPC cover plate according to claim 1, characterized in that: The preparation method of the modified aggregate / fiber composite comprises: Add steel fiber to silane coupling agent and disperse by ultrasonic method; then add kaolin and disperse by ultrasonic method; finally add quartz sand and disperse by ultrasonic method to obtain a mixture; The mixture is first heated to 300-400°C and kept warm for 0.5-1h; then heated to 600-700°C and kept warm for 0.5-1h; then quickly cooled to 300-400°C and kept warm for 0.5-1h; finally quickly cooled to 100-200°C and kept warm for 0.5-1h; after cooling to room temperature, the mixture is discharged and ground to obtain a modified aggregate / fiber composite.

5. The high-strength RPC cover plate according to claim 4, characterized in that: In the method for preparing the modified aggregate / fiber composite, The mass ratio of steel fiber, kaolin and quartz sand is 1~2:3~4:8~10; The amount of silane coupling agent added is 1% to 2% of the total mass of steel fiber, kaolin and quartz sand; The holding time is 0.5~1h, the heating rate is 1~4℃ / min, and the cooling rate is 8~12℃ / min.

6. The high-strength RPC cover plate according to claim 1, characterized in that: The preparation method of the modified carboxyl styrene-butadiene latex comprises: Dispersing nano calcium carbonate and sodium stearate in water to form a dispersion; Dispersing polypropylene fiber in ethanol, adding silane coupling agent, and mixing evenly; adding the dispersion, heating at 80-100° C. for reaction for 1-2 hours, cooling, filtering to obtain a solid product, and drying to obtain a product; The product is added into carboxylated styrene butadiene latex, and mixed evenly to obtain modified carboxylated styrene butadiene latex.

7. The high-strength RPC cover plate according to claim 6, characterized in that: In the preparation method of the modified carboxylated styrene-butadiene latex, The mass ratio of nano calcium carbonate, polypropylene fiber and carboxyl styrene butadiene latex is 0.8-1.2:1-1.6:3-4; The amount of sodium stearate added is 1%~2% of the mass of nano calcium carbonate; The added amount of silane coupling agent is 1% to 2% of the total mass of nano-calcium carbonate and polypropylene fiber.

8. The high-strength RPC cover plate according to claim 1, characterized in that: The powder content of the crushed stone pieces is below 1.0%, the crushing value is below 10%, and the average particle size is 5-10 mm, wherein the content of particles with a diameter below 5 mm does not exceed 5%, and the content of particles with a diameter above 10 mm does not exceed 10%.

9. A method for preparing a high-strength RPC cover plate according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. dry mixing cement, modified mineral admixture and modified aggregate / fiber composite; S2, continue to add admixtures and water, and stir after adding; S3, continue to add modified carboxyl styrene butadiene latex, and stir after adding; S4, continue to add crushed stone pieces, stir after adding, and obtain a mixture; S5, adding the mixed material into a material placing machine; S5, loading the mixed material into the mold from the material placing machine, and vibrating the mold; S6, continue to put steel bars or steel wires into the mixture, and continue to vibrate the mold; S7, smoothing the surface of the mixture and coating it; S8, separating the initially solidified RPC cover plate from the mold to obtain a demoulded RPC cover plate; S9, dry-curing the RPC cover plate and sprinkling water to obtain a high-strength RPC cover plate.

10. The preparation method according to claim 9, characterized in that: In step S1, the dry mixing time is 30s-1min; In step S2, the stirring time is 3-4 minutes; In step S3, the stirring time is 1 to 3 minutes; In step S4, the stirring time is 2 to 3 minutes; In step S5, the time of vibrating the mold is 20 to 40 seconds; In step S6, the time of vibrating the mold is 5 to 15 seconds; In step S8, the initially solidified RPC cover plate is separated from the mold after 18 to 22 hours; In step S9, the RPC cover is dry-cured for 6 to 9 days and then watered.

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