Preparation of eco-type early-strength ultra-high performance concrete by copper tailing sand loaded nanoparticles

Abstract

The application discloses a kind of copper tailing sand load nanoparticles preparation ecological type early strength ultra-high performance concrete, including aggregate, gel material, water, steel fiber and water reducing agent;The aggregate includes copper tailing sand nano carrier, quartz powder and quartz sand;The mass ratio of copper tailing sand nano carrier is 30-50% of the total amount of aggregate, the mass ratio of quartz powder is 5-15% of the total amount of aggregate, and the mass ratio of quartz sand is 40-50% of the total amount of aggregate;The mass ratio of cement, fly ash and silica fume is respectively 60-70%, 5-15% and 15-25% of the total amount of cementitious material;The mass of water is 16%-20% of the mass of cementitious material;The volume fraction of steel fiber is 1-3% of the total volume of ultra-high performance concrete;The mass of water reducing agent is 1.5-3% of the mass of cementitious material.The application has the advantages of improving early strength, optimizing UHPC particle size distribution composition and reducing the production cost of UHPC.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ultra-high performance concrete. More particularly, the present application relates to a kind of copper tailings sand load nanoparticles preparation ecological type early strength ultra-high performance concrete. BACKGROUND

[0002] Ultra-high performance concrete has the advantages of low water-binder ratio, low porosity, good durability and excellent mechanical properties, which can solve the problems of low strength, poor toughness and poor durability of ordinary concrete. However, the use of a large amount of cement, silica fume, fly ash and other cementitious materials, quartz sand and high-quality aggregate such as quartz powder in conventional ultra-high performance concrete (UHPC) results in high cost of UHPC, which limits its popularization and application. The annual discharge of copper tailings in China is more than 300 million tons, but the comprehensive utilization rate is low, and a large amount of tailings are discarded into tailings ponds or tailings dams, occupying a large amount of land, and there are hidden dangers of landslides, mudslides and other natural disasters. In addition, due to the complex chemical composition of copper tailings and the presence of harmful elements such as sulfur, cadmium and arsenic, the resource utilization of copper tailings is further limited. Since copper tailings sand has a relatively good particle size distribution range, it can be used as a substitute for quartz sand and quartz powder to serve as aggregate to optimize the particle size distribution and achieve the comprehensive utilization of copper tailings in a reduced, harmless and high-value manner. SUMMARY

[0003] The purpose of the present application is to provide a method for preparing an ecological type early strength ultra-high performance concrete material using copper tailings sand loaded with nanoparticles. The method uses a special negative pressure roller device to load active nanoparticles such as nano-calcium oxide, nano-magnesium oxide, nano-calcium hydroxide, nano-calcium carbonate, nano-aluminum oxide and nano-silicon dioxide into the micro pores on the surface of copper tailings sand, and mix and stir the nanoparticles with UHPC slurry uniformly. The nanoparticles can serve as nucleation sites for hydration products, promoting the nucleation of hydration products, and in an alkaline environment, the nanoparticles can provide the calcium source, silicon source or aluminum source required by the hydration products, promoting the hydration reaction and thus improving the early strength. In addition, copper tailings sand can replace quartz sand and solidify harmful elements in the tailings, optimize the particle size distribution composition of UHPC and reduce the production cost of UHPC.

[0004] The technical solution adopted by the present application to solve the technical problem is: a copper tailings sand loaded with nanoparticles to prepare an ecological type early strength ultra-high performance concrete, which comprises aggregate, cementitious material, water, steel fiber and water reducing agent.

[0005] The aggregate includes copper tailings sand nano-loaded body, quartz powder and quartz sand. The mass fraction of the copper tailings sand nano-loaded body is 30-50% of the total amount of the aggregate, the mass fraction of the quartz powder is 5-15% of the total amount of the aggregate, and the mass fraction of the quartz sand is 40-50% of the total amount of the aggregate.

[0006] The gel material includes cement, fly ash and silica ash; the mass ratio of cement, fly ash and silica ash is 60-70%, 5-15% and 15-25% respectively in the total amount of gel material;

[0007] The mass of water is 16%-20% of the mass of gel material;

[0008] The volume content of steel fiber is 1-3% of the total volume of ultra-high performance concrete;

[0009] The mass of water reducing agent is 1.5-3% of the mass of gel material.

[0010] Preferably, the copper tailings sand nanometer carrier loads the nanometer particles on the copper tailings sand through a negative pressure roller device; the negative pressure roller device is composed of a nanometer particle loading box, a roller and a negative pressure device connected in sequence.

[0011] Preferably, the nanometer particle loading box is coaxially connected with the roller, the contact surface between the nanometer particle loading box and the roller is a porous screen, the pore size is 200-250nm; the rotation speed of the roller is to ensure that the nanometer particles can be uniformly loaded in the pores of the copper tailings sand during the negative pressure process; a porous screen with a pore size smaller than the minimum particle size of the nanometer particles is arranged between the roller and the negative pressure device; the negative pressure is 0.5kPa-1.5kPa; the length to diameter ratio of the roller is 15-30:1.

[0012] Preferably, the preparation method of the copper tailings sand nanometer carrier is as follows: the nanometer particles are evenly divided into 3-5 parts, one part is loaded into the nanometer particle loading box and is tightly connected with the roller, the other end of the roller is connected with the negative pressure device, then the roller is started, the negative pressure device is started after the copper tailings sand stably rotates in the roller, the negative pressure device is closed after 1-2 minutes, and the roller is closed after the air pressure is stable; the remaining nanometer particles are repeatedly prepared by the above method until all the nanometer particles are added, and a uniform copper tailings sand nanometer carrier is obtained.

[0013] Preferably, the mass ratio of the nanometer particles to the copper tailings sand is 5-12:100.

[0014] Preferably, the copper tailings sand has pores on the surface, and the pore size is 100-200nm.

[0015] Preferably, the particle size of the copper tailings sand is 1μm-400μm, and the average particle size is 90-120μm.

[0016] Preferably, the particle size of the nanometer particles is 20-50nm.

[0017] Preferably, the nanometer particles are composed of three components A, B and C.

[0018] The A component is one or two of nano calcium oxide, nano magnesium oxide, nano calcium hydroxide,

[0019] The B component is one or two of nano aluminum oxide, nano silicon dioxide

[0020] The C component is nano calcium carbonate.

[0021] Preferably, the total mass ratio of the three components A, B and C is (4-8):(2-5):1.

[0022] The present application at least includes the following beneficial effects: the present application proposes a method for preparing an ecological early-strength ultra-high performance concrete material by using copper tailings sand loaded with nano particles. When the copper tailings sand is directly used to replace quartz powder and quartz sand, a large number of holes exist on the surface of the copper tailings sand, and superfine powder such as silica fume will adhere to the holes during the mixing of the powder and the aggregate. When water and water reducing agent are mixed, due to the large amount of silica fume adsorbed in the copper tailings, the amount of water reducing agent required for mixing will increase under the same water consumption, and the fluidity will decrease. In order to solve the problems caused by the use of copper tailings sand to replace the conventional aggregate of UHPC, the present patent proposes to load active nano particles on the copper tailings sand, which can fill the surface holes and optimize the surface morphology of the copper tailings sand. After the copper tailings nano carrier is added to the well-mixed UHPC slurry, the nano particles on the carrier can be prevented from being detached due to collision during the mixing of the powder and the aggregate, and the mixing water can also be prevented from being adsorbed after the copper tailings are added, thereby causing the fluidity to decrease. After the copper tailings sand nano carrier is uniformly mixed with the slurry, the nano particles act as nucleation sites for the hydration products, promoting the nucleation of the hydration products, and the nano particles can provide the required calcium source, silicon source or aluminum source for the hydration products in an alkaline environment, refining the crystal size of the hydration products, thereby improving the early strength. In addition, nano calcium oxide, nano magnesium oxide or nano calcium hydroxide can undergo a secondary hydration reaction with the hydration products to generate ettringite, which fills the capillary pores, further optimizing the slurry density and reducing material shrinkage. The copper tailings sand loaded with nano particles can replace quartz powder and quartz sand, reduce the use of high-quality aggregate, improve the comprehensive utilization rate of copper tailings sand, and utilize the low porosity characteristics of UHPC to solidify harmful elements in the copper tailings.

[0023] Other advantages, objects, and features of the application will be apparent from the following specification and claims. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the negative pressure roller device of the present application.

[0025] 1 - nano particle loading box; 2 - roller; 3 - negative pressure device. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the drawings. Those skilled in the art will be able to implement the present application based on the description. Before the present application is described in detail with reference to the drawings, it is to be noted that the technical solutions and technical features provided in the present application, including the following description, can be combined with each other without conflict, if possible.

[0027] In addition, the embodiments of the present application involved in the following description are generally only embodiments of a part of the present application, not all embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments in the present application without creative labor should belong to the scope of protection of the present application.

[0028] The present application will be described in detail below with reference to the drawings. Those skilled in the art will be able to implement the present application based on the description. Before the present application is described in detail with reference to the drawings, it is to be noted that the technical solutions and technical features provided in the present application, including the following description, can be combined with each other without conflict, if possible.

[0029] As shown in Figure 1 The present application provides a kind of copper tailing sand load nanoparticle preparation ecological type early strength super high performance concrete, including aggregate, gel material, water, steel fiber and water reducing agent;

[0030] The aggregate includes copper tailing sand nano carrier, quartz powder and quartz sand;The mass ratio of copper tailing sand nano carrier is 30-50% of the total amount of aggregate, the mass ratio of quartz powder is 5-15% of the total amount of aggregate, and the mass ratio of quartz sand is 40-50% of the total amount of aggregate;

[0031] The gel material includes cement, fly ash and silica fume;The mass ratio of cement, fly ash and silica fume is 60-70%, 5-15% and 15-25% of the total amount of cementitious material respectively;

[0032] The mass of water is 16%-20% of the mass of cementitious material;

[0033] The volume fraction of steel fiber is 1-3% of the total volume of super high performance concrete;

[0034] The mass of water reducing agent is 1.5-3% of the mass of cementitious material.

[0035] The application provides a method for preparing an ecological early-strength ultra-high performance concrete material by using copper tailing sand loaded with nanoparticles. The nanoparticles are loaded in the holes on the surface of the copper tailing sand, so that the surface morphology of the copper tailing sand is optimized. The copper tailing nano-carrier is added into the stirred UHPC slurry, so that the nanoparticles on the carrier are prevented from being separated during the mixing of the powder and the aggregate, and the mixing water is prevented from being absorbed after the copper tailing is added, so that the fluidity is reduced. After the copper tailing sand nano-carrier is uniformly mixed with the slurry, the nanoparticles serve as nucleation sites for the hydration products, promote the nucleation of the hydration products, and provide the required calcium source, silicon source or aluminum source for the hydration products in an alkaline environment, so that the crystal size of the hydration products is refined, and the early strength is improved. In addition, the nano-calcium oxide, nano-magnesium oxide or nano-calcium hydroxide can react with the hydration products to generate ettringite, which is filled in the capillary pores, so that the slurry density is further optimized and the material shrinkage is reduced. The copper tailing sand loaded with the nanoparticles is used to replace the quartz powder and quartz sand, so that the use of high-quality aggregate is reduced, the comprehensive utilization rate of the copper tailing sand is improved, and the harmful elements in the copper tailing are solidified by using the low porosity of the UHPC.

[0036] The technical solution can further include the following technical details to better achieve the technical effects: the copper tailing sand nano-carrier loads the nanoparticles on the copper tailing sand through a negative pressure roller device; the negative pressure roller device is sequentially connected by a nanoparticle loading box 1, a roller 2 and a negative pressure device 3.

[0037] The technical solution can further include the following technical details to better achieve the technical effects: the nanoparticle loading box and the roller are both cylindrical and have equal cross-sectional areas; the nanoparticle loading box and the roller are coaxially connected, and the centers thereof are threadedly connected; the contact surface between the nanoparticle loading box and the roller is a porous screen, and the pore size is 200-250nm, which is slightly larger than the maximum particle size of the nanoparticles, so that the nanoparticles can be sucked into the roller under the action of negative pressure; the rotation speed of the roller is 200-400r / min, so that the nanoparticles can be uniformly loaded in the holes of the copper tailing sand under the action of negative pressure; a porous screen is arranged between the roller and the negative pressure device, and the pore size is slightly smaller than the minimum particle size of the nanoparticles, so as to prevent the nanoparticles from being sucked out of the roller; the negative pressure is 0.5kPa-1.5kPa, so as to ensure that the nanoparticles are sucked into the roller, and prevent the copper tailing sand from being accumulated on one side due to excessive negative pressure; the length-diameter ratio of the roller is 15-30:1, so as to ensure that the nanoparticles have sufficient time and a large area to contact the copper tailing sand.

[0038] The technical scheme can further include the following technical details to better achieve the technical effects: the preparation method of the copper tailing sand nano carrier is that: the nanoparticles are evenly divided into 3-5 parts, one part is loaded into a nanoparticle loading box and is tightly connected with a roller, the other end of the roller is connected with a negative pressure device, then the roller is started, the negative pressure device is started after the copper tailing sand stably rotates in the roller, the negative pressure device is closed after 1-2 min, and the roller is closed after the air pressure is stable; the remaining nanoparticles are repeatedly prepared by the above method until all the nanoparticles are added, and a uniform copper tailing sand nano carrier is obtained.

[0039] The technical scheme can further include the following technical details to better achieve the technical effects: the mass ratio of the nanoparticles to the copper tailing sand is 5-12:100, which can ensure that enough nanoparticles are filled in the pores of the copper tailing sand under the action of negative pressure, and the surface morphology of the copper tailing sand is optimized.

[0040] The technical scheme can further include the following technical details to better achieve the technical effects: the copper tailing sand surface has pores with a size of 100-200 nm to provide a loading space for the nanoparticles.

[0041] The technical scheme can further include the following technical details to better achieve the technical effects: the particle size of the copper tailing sand is 1-400 μm, and the average particle size is 90-120 μm, which is between the particle size of quartz powder and quartz sand, so that the particle size distribution of the aggregate can be optimized to form a continuous and compact packing of aggregate particles.

[0042] The technical scheme can further include the following technical details to better achieve the technical effects: the particle size of the nanoparticles is 20-50 nm to ensure that the nanoparticles can be loaded on the surface of the copper tailing sand.

[0043] The technical scheme can further include the following technical details to better achieve the technical effects: the nanoparticles are composed of three components A, B and C.

[0044] The component A is one or two of nano calcium oxide, nano magnesium oxide and nano calcium hydroxide,

[0045] The component B is one or two of nano aluminum oxide and nano silicon dioxide

[0046] The component C is nano calcium carbonate.

[0047] On the one hand, the nanoparticles can act as nucleation sites for hydration products to promote nucleation of hydration products, and on the other hand, the nanoparticles can provide calcium source, silicon source or aluminum source required by hydration products in an alkaline environment to refine the crystal size of hydration products, thereby improving the early strength.

[0048] The technical scheme can further include the following technical details to better achieve the technical effects: the total mass ratio of the three components A, B and C is (4-8):(2-5):1.

[0049] The technical scheme can further include the following technical details to better achieve the technical effects: the particle size range of the quartz powder is 0.3-120 mu m, and the average particle size is 30-50 mu m, which can fill the internal pores of the material and improve the compactness of the material.

[0050] The technical scheme can further include the following technical details to better achieve the technical effects: the particle size range of the quartz sand is 0.38-2.36 mm, and the average particle size is 0.8-1.2 mm, which acts as the skeleton of the material.

[0051] The technical scheme can further include the following technical details to better achieve the technical effects: the cement is a commercially available portland cement, and the mark can be selected as P·II 42.5, P·O 42.5R, P·II 52.5, P·II 52.5R, P·O 52.5, and the average particle size range is 10-40 mu m.

[0052] The technical scheme can further include the following technical details to better achieve the technical effects: the fly ash should at least meet the performance index requirements of I-grade ash, and the sieve residue of 45 mu m square hole screen should not be greater than 5%, and the average particle size is 1-5 mu m. The spherical particles in the fly ash can improve the fluidity of the slurry, and at the same time, the "volcanic ash effect" can be played to improve the late strength of the material.

[0053] The technical scheme can further include the following technical details to better achieve the technical effects: the SiO2 content of the silica fume is not less than 95%, the specific surface area is not less than 15000 m 2 / kg, and the average particle size range is 0.1-0.2 mu m. The silica fume can fill the interface zone of the slurry to improve the compactness of the slurry, and at the same time, the "volcanic ash effect" can be played to improve the strength and durability of the material.

[0054] The technical scheme can further include the following technical details to better achieve the technical effects: the water reducing agent is a polycarboxylic acid superplasticizer, and the water reducing rate is greater than 30%, and the solid content is greater than 30%.

[0055] The technical scheme can further include the following technical details to better achieve the technical effects: the fiber is a high-strength steel fiber, and the volume content is 1-3%, which is used to improve the toughness of the material.

[0056] The copper tailing sand loaded nanoparticles of the present application are used to prepare the ecological early-strength UHPC in Examples 1 and 2. Table 1 is the copper tailing sand loaded nanoparticle ratio, and Table 2 is the copper tailing sand loaded nanoparticle ratio for preparing the ecological early-strength UHPC. The comparative group does not add the copper tailing sand nanoparticle carrier. It should be noted that in Examples 1, 2 and Comparative Example 1, the particle size of the raw materials and the preparation process are the same except for the different ratios.

[0057] Table 1 Copper tailing sand loaded nanoparticle ratio (100 parts of copper tailing sand)

[0058]

[0059] Table 2 Copper tailing sand loaded nanoparticle ratio for preparing the ecological early-strength UHPC (kg / m3)

[0060]

[0061]

[0062] The UHPC materials prepared in Examples 1-2 and the comparative group are tested for performance, and the test results are shown in Table 3.

[0063] Table 3 Performance of each example

[0064]

[0065] As shown in Table 1, the nanometer calcium oxide, nanometer magnesium oxide, nanometer calcium carbonate, nanometer silicon dioxide, nanometer aluminum oxide, etc. are loaded on the surface of the copper tailing sand using a negative pressure roller device to form a copper tailing sand nanoparticle carrier, and replace high-quality aggregates such as quartz powder and quartz sand. The slurry of cement, fly ash, silica fume, quartz powder, quartz sand and water, and water reducing agent is added, and finally steel fibers are added, as shown in Table 2. As shown in Table 3, the UHPC material prepared by replacing the quartz powder and quartz sand with the copper tailing sand nanoparticle carrier has a slightly lower spread than the conventional UHPC, but the 28d compressive strength is similar to that of the conventional UHPC, but the 1d compressive strength is increased by 18-24% compared to the conventional UHPC, indicating that the early strength is significantly improved. The super high performance concrete prepared in this way realizes the resource utilization of copper tailing sand and can improve the early strength of UHPC.

[0066] Although the embodiments of the present application have been disclosed as above, they are not limited to the use listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and the examples shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method for preparing eco-friendly, early-strength, ultra-high-performance concrete using copper tailings sand loaded with nanoparticles, characterized in that, Includes aggregates, gelling materials, water, steel fibers, and water-reducing agents; The aggregate includes copper tailings nano-supported material, quartz powder, and quartz sand; the mass percentage of copper tailings nano-supported material is 30-50% of the total aggregate, the mass percentage of quartz powder is 5-15% of the total aggregate, and the mass percentage of quartz sand is 40-50% of the total aggregate. The cementitious materials include cement, fly ash, and silica fume; the mass percentages of cement, fly ash, and silica fume are 60-70%, 5-15%, and 15-25% of the total cementitious materials, respectively. The water content should be 16%-20% of the mass of the cementitious material. The volumetric content of steel fiber in ultra-high performance concrete is 1-3% of the total volume. The water-reducing agent should be 1.5-3% of the mass of the cementitious material. A copper tailings nanoparticle support is generated by loading nanoparticles onto copper tailings using a negative pressure roller device. The negative pressure roller device consists of a nanoparticle loading box, a roller, and a negative pressure device connected sequentially. The nanoparticle loading box is coaxially connected to the roller, and the contact surface between the loading box and the roller is a porous sieve with a pore size of 200-250 nm. The roller rotation speed is designed to ensure that the nanoparticles are uniformly loaded into the pores of the copper tailings during the negative pressure process. A porous sieve with a pore size smaller than the minimum particle size of the nanoparticles is installed between the roller and the negative pressure device. The negative pressure is 0.5 kPa-1.5 kPa, and the length-to-diameter ratio of the roller is 15-30:

1. The surface of copper tailings sand has pores of 100-200 nm; the particle size range of copper tailings sand is 1 μm-400 μm, and the average particle size is 90-120 μm. The preparation method of copper tailings nano-support is as follows: divide the nanoparticles into 3-5 portions, take one portion and put it into the nanoparticle loading box and connect it tightly to the roller. Connect the other end of the roller to the negative pressure device, then turn on the roller. After the copper tailings rotate stably in the roller, turn on the negative pressure device. After 1-2 minutes, turn off the negative pressure device. After the air pressure stabilizes, turn off the roller. Repeat the above preparation method for the remaining nanoparticles until all the nanoparticles are added to obtain a uniform copper tailings nano-support.

2. The method for preparing eco-friendly, early-strength, ultra-high-performance concrete using copper tailings sand loaded with nanoparticles as described in claim 1, characterized in that, The mass ratio of the nanoparticles to copper tailings is 5-12:

100.

3. The method for preparing eco-friendly, early-strength, ultra-high-performance concrete using copper tailings sand loaded with nanoparticles as described in claim 1, characterized in that... The nanoparticles have a particle size of 20-50 nm.

4. The method for preparing eco-friendly, early-strength, ultra-high-performance concrete using copper tailings sand loaded with nanoparticles as described in claim 1, characterized in that, The nanoparticles are composed of a compound of three components, A, B, and C. Component A consists of one or two of nano-calcium oxide, nano-magnesium oxide, and nano-calcium hydroxide. Component B consists of one or both of nano-alumina and nano-silica. Component C is nano-calcium carbonate.

5. The method for preparing eco-friendly, early-strength, ultra-high-performance concrete using copper tailings sand loaded with nanoparticles as described in claim 4, characterized in that, The total mass ratio of components A, B, and C is (4-8):(2-5):1.

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