Preparation method and application of conductive aggregate
By treating fine aggregates with a double-layer coating of carbon nanotubes and polyacrylic acid, the problem of difficult dispersion of carbon nanotubes in cement-based materials is solved, achieving stable dispersion and high conductivity of conductive aggregates, which is suitable for smart buildings and structural health monitoring.
Patent Information
- Application Number
- CN202511241931.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-02
- Publication Date
- 2025-12-16
AI Technical Summary
In existing technologies, carbon nanotubes are difficult to disperse in cement-based materials, suffer from severe agglomeration, and are difficult to control in terms of dosage, resulting in unstable conductivity and difficulty in constructing a good conductive network.
Fine aggregates coated with a double layer of carbon nanotubes and polyacrylic acid are used. Through ultrasonic cleaning, stirring and heat treatment, a core-shell structure with a uniform carbon nanotube conductive layer and a polyacrylic acid resin adhesive layer is formed, which improves dispersibility and interfacial bonding.
It achieves good dispersion and stability of conductive aggregates in cement-based composite materials, significantly reduces resistivity, and balances conductivity and mechanical strength, making it suitable for a variety of engineering applications.
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Figure CN121135202A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of building materials, and particularly relates to a preparation method of conductive aggregate and application thereof. BACKGROUND
[0002] With the development of intelligent buildings and structural health monitoring technology, the demand for cement-based materials with electrical function characteristics is increasing. As a functional building material with structural load-bearing and electrical response characteristics, conductive concrete is widely used in deicing and snow melting, people / vehicle flow monitoring, self-sensing structure, antistatic floor and other scenes.
[0003] At present, the main ways to improve the electrical conductivity of cement-based materials include adding carbon fibers, graphite powder, carbon nanotubes (CNT), conductive high polymer or conductive aggregate. Among them, adding carbon nanotubes can significantly improve the electrical conductivity of the material, but there are problems such as difficulty in dispersion, serious agglomeration and difficulty in dosage control, which are not conducive to engineering application.
[0004] Therefore, developing a conductive aggregate with carbon nanotubes as a functional source, good dispersibility, interface combination and preparation controllability has become a key technical path to solve the above problems. SUMMARY
[0005] The purpose of the present application is to provide a preparation method of conductive aggregate adopting carbon nanotubes and polyacrylic acid (PAA) double-layer coated fine aggregate to improve its dispersibility and electrical conductivity in cement-based composite materials.
[0006] To achieve the above purpose, the technical scheme of the present application is as follows:
[0007] A preparation method of conductive aggregate, comprising the following steps:
[0008] S1, taking dry fine aggregate, placing it in an ultrasonic cleaner for surface cleaning and roughening treatment;
[0009] S2, preparing a CNT dispersion liquid, adding carbon nanotubes into ethanol or acetone, and adding a surfactant, and preparing a uniform dispersion liquid by ultrasonic stirring;
[0010] S3, immersing the fine aggregate obtained in step S1 into a polyacrylic acid resin solution, stirring at room temperature for 10-60 min, heating at a temperature of 120-200 DEG C, and stirring until the coating is dry, to obtain fine aggregate with a polyacrylic acid resin adhesion layer wrapped on the surface;
[0011] S4, immersing the fine aggregate obtained in step S3 into the CNT dispersion liquid prepared in step S2, and stirring for 3-15 min, so that the carbon nanotubes are uniformly adsorbed on the surface of the aggregate;
[0012] S5, further control the stirring temperature to be 100-200℃, continuously stirring for 5-30min at a speed of 50-80rpm, screen with a 60 mesh screen, and clean the coarse solid obtained by screening;
[0013] S6, dry the coarse solid obtained in step S5 at 60-90℃ for 24-72h, so that the polyacrylic acid resin forms a uniform and dense outer layer coating, and a double-layer coated conductive aggregate is obtained.
[0014] Preferably, the fine aggregate is natural sand or machine-made sand with a particle size of 0.075-4.75mm and a water absorption rate of less than 2.5%.
[0015] Preferably, the mass ratio of carbon nanotubes to fine aggregate is 0.1-1%, and the mass ratio of polyacrylic acid resin to fine aggregate is 1-5%.
[0016] Preferably, the polyacrylic acid resin solution is an aqueous emulsion or a dilute solution with a mass concentration of 5-30%.
[0017] Preferably, the drying process adopts a stepwise heating mode, including a low-temperature pre-drying stage and a high-temperature curing stage.
[0018] Preferably, the conductive aggregate is coated with an inner carbon nanotube adsorption layer and an outer polyacrylic acid resin coating layer, forming a core-shell structure.
[0019] Preferably, the overall thickness of the coating layer of the conductive aggregate is 5-100μm, and the aggregate surface is uniformly distributed and the coating layer is firmly bonded.
[0020] Preferably, the conductive aggregate cement is used to prepare a cement-based conductive composite material, which includes cement, the conductive aggregate, water, additives and other conventional aggregates, and the content of the conductive aggregate is 1-10% of the mass of the cementitious material.
[0021] Preferably, the conductivity of the cement-based conductive composite material is 10 -2 -10 -4 S / cm, the compressive strength is greater than 30MPa, and the resistivity stability is within ±5%.
[0022] Compared with the prior art, the advantages of the present application are:
[0023] Through CNT+PAA double-layer coating, good dispersibility of the conductive aggregate and cement paste interface bonding force are achieved.
[0024] The finished material has stable electrical conductivity, and the resistivity is significantly lower than that of the control group with only CNT or only PAA coating.
[0025] The process is controllable and suitable for industrial mass production.
[0026] The material performance is balanced, the electrical conductivity and the mechanical strength are considered, and the material is suitable for various engineering application requirements.
[0027] The fine aggregate is coated with polyacrylic resin, so that the surface of the fine aggregate is uniformly covered with a polyacrylic resin adhesion layer (the polyacrylic resin adhesion layer covered on the surface of the fine aggregate can soften within a certain temperature range to adhere to carbon nanotube powder to form a conductive layer.); then the carbon nanotube powder and the fine aggregate with the polyacrylic resin coating on the surface are continuously stirred and dried under heating according to a preset mass ratio, and the fine aggregate with the double-layer coating of the polyacrylic resin adhesion layer and the carbon nanotube conductive layer on the surface is obtained after screening and cleaning and drying, that is, the conductive aggregate. Thus, the carbon nanotube conductive layer uniformly coated on the surface of the fine aggregate enables the fine aggregate to have electrical conductivity. Therefore, an excellent conductive framework can be built in the cement-based composite material at a very low amount of carbon material (only 0.05wt% of the mass of cement), so as to form an excellent conductive path, thereby obtaining a conductive cement-based composite material with excellent performance. In addition, the conductive cement-based composite material prepared based on the conductive aggregate process avoids the direct introduction of carbon nanomaterial into the alkaline cement matrix, and the carbon nanomaterial is uniformly dispersed in the cement matrix through the adhesion of the polyacrylic resin adhesion layer, so that the carbon nanomaterial is prevented from being aggregated and the carbon nanomaterial is prevented from being separated from the cement matrix, thereby avoiding the problems of defects and the inability to build a good conductive network.
[0028] The material is difficult to uniformly disperse, thereby causing defects and the inability to build a good conductive network. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 It is a schematic diagram of the preparation process of the conductive aggregate in the embodiment of the application.
[0030] Figure 2 It is a contrast diagram of the appearance of the ordinary aggregate and the conductive aggregate in the embodiment of the application.
[0031] Figure 3 It is a scanning electron microscope diagram of the conductive aggregate in the embodiment of the application.
[0032] Figure 4 It is a scanning electron microscope diagram of the conductive cement-based composite material in the embodiment of the application.
[0033] Figure 5 It is a schematic diagram of the conductive cement-based composite material in the embodiment of the application.
[0034] Figure 6 It is a contrast schematic diagram of the conductive mechanism of the conductive cement-based composite material in the embodiment of the application. DETAILED DESCRIPTION
[0035] The application will be described in detail below with reference to the drawings.
[0036] REFERENCE Figures 1-6 , wherein for Figure 3 The left graph is an enlarged view of the block region of the right graph; forFigure 6 The left figure is a schematic diagram of the conductive mechanism of ordinary cement-based composite material after adding conductive phase, and the right figure is a schematic diagram of the conductive mechanism of conductive cement-based composite material based on conductive aggregate.
[0037] A conductive aggregate and a preparation method of conductive cement-based composite material are prepared by the following steps:
[0038] Step one, the fine aggregate is mixed with polyacrylic acid resin solution, heated and continuously stirred, the solid phase is collected by screening, and the fine aggregate with a surface covered by polyacrylic acid resin adhesion layer is obtained;
[0039] Step two, the fine aggregate obtained in the previous step is mixed with carbon nanotube powder, and the fine aggregate with a surface uniformly coated with a double-layer coating of polyacrylic acid resin adhesion layer and carbon nanotube conductive layer is obtained by heating and stirring, separation by screen mesh and drying, that is, a conductive aggregate.
[0040] Further, the fine aggregate with a surface covered by polyacrylic acid resin adhesion layer in step one is prepared by the following method:
[0041] The fine aggregate is mixed with polyacrylic acid resin emulsion for 1-10 min, heated at a temperature of 120-200℃, and stirred until the coating is dry, to obtain fine aggregate with a surface coated with polyacrylic acid resin adhesion layer; wherein the fine aggregate is porous ceramsite, river sand or machine-made sand; the mass ratio of fine aggregate to polyacrylic acid resin coating is 0.5-2%.
[0042] The polyacrylic acid resin adhesion layer covering the surface of the fine aggregate can soften within a certain temperature range to adhere to the carbon nanotube powder to form a conductive layer.
[0043] Further, the particle size of the fine aggregate is 250μm-2.36mm, and the water absorption rate in 24h is greater than 1.0%.
[0044] Further, the fine aggregate with a surface uniformly coated with a double-layer coating of polyacrylic acid resin adhesion layer and carbon nanotube conductive layer in step two is prepared by the following method:
[0045] The fine aggregate with a surface coated with polyacrylic acid resin adhesion layer is mixed with carbon nanotube powder, stirred for 3-10 min, and continuously stirred at a speed of 50-80 rpm for 5-30 min at a temperature of 120-200℃; then, the coarser solid obtained by screening is washed and dried at a temperature of 60-80℃ for 24-72h, to finally obtain conductive fine aggregate with a surface uniformly coated with a double-layer coating of polyacrylic acid resin adhesion layer and carbon nanotube conductive layer;
[0046] Further, the mass ratio of the carbon nanotube powder and the fine aggregate coated with the polyacrylic resin coating layer is 0.5-2%;
[0047] Further, the preparation method of the conductive cement-based composite material based on the conductive aggregate is as follows:
[0048] The water reducing agent and mixing water are pre-mixed for use; then the conductive aggregate and the cement are mixed; the water solution containing the water reducing agent is added in the mixing process, and the conductive cement composite material is obtained after stirring for 4 min; finally, the conductive cement-based composite material based on the conductive aggregate is obtained by pouring into a mold; wherein the mass ratio of the conductive aggregate to the natural aggregate in the cement-based composite material is 20-100%.
[0049] Further, the preparation method of the conductive cement-based composite material based on the conductive aggregate and the conductive cement-based material is as follows:
[0050] The water reducing agent and mixing water are pre-mixed for use; then the conductive aggregate, the conductive material and the cement are mixed; the water solution containing the water reducing agent is added in the mixing process, and the conductive cement composite material is obtained after stirring for 4 min; finally, the conductive cement-based composite material based on the conductive aggregate is obtained by pouring into a mold; wherein the mass ratio of the conductive aggregate to the natural aggregate in the cement-based composite material is 20-100%.
[0051] The conductive aggregate prepared by the method can be used as a health monitoring material for monitoring the health of concrete structures, as a raw material for road snow melting and deicing, and as a raw material for electromagnetic shielding concrete. Specific embodiments
[0053] A preparation method of a conductive aggregate and a self-sensing cement-based composite material with nano-interface modification, comprising: coating a polyacrylic resin adhesive layer on the surface of a fine aggregate; preparing a fine aggregate with a double-layer coating of a polyacrylic resin adhesive layer and a carbon nanotube conductive layer on the surface in sequence and uniformly; and preparing a conductive cement-based composite material.
[0054] Reference Figures 1-6 As shown in the drawings, according to the preparation method of the conductive aggregate and the self-sensing cement-based composite material based on the conductive aggregate (or combined with the conductive cement-based material) provided by the application, the first embodiment to the sixth embodiment adopt different parameter conditions to prepare the conductive graphene aggregate and the conductive cement-based composite material, and the resistivity index of the conductive aggregate in the natural stacking state is tested; in addition, the 28d mechanical strength, the 28d resistivity and the piezoresistive performance of the conductive cement-based composite material are characterized.
[0055] First embodiment
[0056] The preparation method of the conductive aggregate in this embodiment comprises:
[0057] The fine aggregate and the polyacrylic resin emulsion were placed in a wide-mouthed polytetrafluoroethylene basin in a mass ratio of 100:4, continuously stirred at a stirring speed of 60 rpm for 5 min using a stirrer, then placed in a heating state at 120°C, continuously stirred at a stirring speed of 60 rpm for 10 min using a stirrer, and the mixture was fully dried to obtain fine aggregate coated with a polyacrylic resin coating layer.
[0058] The fine aggregate coated with a polyacrylic resin coating layer and the carbon nanotube powder were placed in a wide-mouthed polytetrafluoroethylene basin in a mass ratio of 100:1, continuously stirred at a stirring speed of 60 rpm for 5 min using a stirrer, then placed in a heating state at 200°C, continuously stirred at a stirring speed of 60 rpm for 10 min using a stirrer, and finally the fine aggregate was separated using a 60-mesh sieve, washed with running water, and placed in a 60°C drying oven for drying to obtain fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer in sequence, i.e., conductive aggregate.
[0059] Second embodiment
[0060] The conductive aggregate preparation method of the present embodiment is different from that of the first embodiment in that, in the present embodiment, the fine aggregate coated with a polyacrylic resin coating layer and the carbon nanotube powder were placed in a wide-mouthed polytetrafluoroethylene basin in a mass ratio of 10000:5, continuously stirred at a stirring speed of 80 rpm for 4 min using a stirrer, then placed in a heating state at 200°C, continuously stirred at a stirring speed of 80 rpm for 10 min using a stirrer, and finally the fine aggregate was separated using a 60-mesh sieve, washed with running water, and placed in an 80°C drying oven for drying to obtain fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer in sequence, i.e., conductive aggregate. The remaining steps are the same as those of the first embodiment.
[0061] Third embodiment
[0062] The conductive aggregate preparation method of the present embodiment is different from that of the first embodiment in that, in the present embodiment, the fine aggregate coated with a polyacrylic resin coating layer and the carbon nanotube powder were placed in a wide-mouthed polytetrafluoroethylene basin in a mass ratio of 1000:1, continuously stirred at a stirring speed of 70 rpm for 5 min using a stirrer, then placed in a heating state at 180°C, continuously stirred at a stirring speed of 70 rpm for 10 min using a stirrer, and finally the fine aggregate was separated using a 60-mesh sieve, washed with running water, and placed in a 70°C drying oven for drying to obtain fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer in sequence, i.e., conductive aggregate. The remaining steps are the same as those of the first embodiment.
[0063] Fourth embodiment
[0064] The preparation method of the conductive aggregate of the embodiment is different from that of the first embodiment. In the embodiment, the fine aggregate coated with a polyacrylic resin coating on the surface and the carbon nanotube powder are placed in a wide-mouth polytetrafluoroethylene basin at a mass ratio of 1000:3, stirred at a speed of 75 rpm for 5 min using a stirrer, then placed in a heating state at 160°C, stirred at a speed of 75 rpm for 10 min using a stirrer, and finally separated from the fine aggregate using a 60-mesh sieve, washed with running water, and dried in a drying oven at 80°C to obtain the fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer on the surface in sequence, i.e., the conductive aggregate. The remaining steps are the same as those of the first embodiment.
[0065] Fifth embodiment
[0066] The preparation method of the conductive aggregate of the embodiment is different from that of the first embodiment. In the embodiment, the fine aggregate coated with a polyacrylic resin coating on the surface and the carbon nanotube powder are placed in a wide-mouth polytetrafluoroethylene basin at a mass ratio of 1000:5, stirred at a speed of 75 rpm for 5 min using a stirrer, then placed in a heating state at 160°C, stirred at a speed of 75 rpm for 10 min using a stirrer, and finally separated from the fine aggregate using a 60-mesh sieve, washed with running water, and dried in a drying oven at 80°C to obtain the fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer on the surface in sequence, i.e., the conductive aggregate. The remaining steps are the same as those of the first embodiment.
[0067] Sixth embodiment
[0068] The preparation method of the conductive aggregate of the embodiment is different from that of the first embodiment. In the embodiment, the fine aggregate coated with a polyacrylic resin coating on the surface and the carbon nanotube powder are placed in a wide-mouth polytetrafluoroethylene basin at a mass ratio of 1000:7, stirred at a speed of 75 rpm for 5 min using a stirrer, then placed in a heating state at 160°C, stirred at a speed of 75 rpm for 10 min using a stirrer, and finally separated from the fine aggregate using a 60-mesh sieve, washed with running water, and dried in a drying oven at 80°C to obtain the fine aggregate coated with a polyacrylic resin adhesion layer and a carbon nanotube conductive layer on the surface in sequence, i.e., the conductive aggregate. The remaining steps are the same as those of the first embodiment.
[0069] In combination with the following table and the first to sixth embodiments described above, the test results are as follows:
[0070] For the first, second, third, fourth, fifth, and sixth embodiments, the mass ratio of the fine aggregate to the carbon nanotube is 100:1, 10000:5, 1000:1, 1000:3, 1000:5, and 1000:7, respectively, and the resistivity Ωcm is 328, 120000, 19785, 2193, 1086, and 797, respectively.
[0071] In combination with the above, the technical solution provided by the present application can greatly reduce the resistivity of the aggregate, and is conducive to improving the conductivity of the conductive cement-based composite material. Compared with natural fine aggregate and conductive aggregate, the color of the aggregate changes from white to black (see Figure 2 ), indicating that the carbon nanotubes have successfully adhered to the surface of the fine aggregate; in addition, it can be seen from Figure 3 that the surface of the conductive aggregate particles prepared in the example has a layer of carbon nanotube conductive layer, which can be clearly seen by using a scanning electron microscope.
[0072] Seventh embodiment
[0073] The conductive cement-based composite material preparation method based on conductive aggregate and conductive cement-based material in this embodiment comprises the following steps:
[0074] The water reducing agent and mixing water are pre-mixed for use; then the chopped carbon fibers (6mm, the mass ratio of the chopped carbon fibers to cement is 5:1000), the conductive aggregate (the conductive aggregate completely replaces the natural fine aggregate, that is, 1350g of the conductive aggregate per unit) and the cement are mixed; the water solution containing the water reducing agent is slowly added during stirring, and the conductive cement composite material (the water-cement ratio is 0.4) is obtained after stirring for 4min; finally, the mixture is poured into a mold, four parallel copper electrode sheets are inserted, and the conductive cement mortar based on the conductive framework structure design is obtained.
[0075] The water reducing agent is a polycarboxylic acid high-performance water reducing agent; the water reducing agent is 1% of the mass of the cement; the cement is conventional 42.5 ordinary portland cement
[0076] The fine aggregate is river sand, the particle size is 75μm 2.36mm, and the water absorption rate in 24h is 0.5 1.0%.
[0077] Eighth embodiment
[0078] The conductive cement-based composite material preparation method based on conductive aggregate in this embodiment is different from the seventh embodiment in that, in this embodiment, the fine aggregate, the conductive aggregate (the conductive aggregate replaces 80% of the natural fine aggregate, that is, 1080g of the conductive aggregate and 270g of the fine aggregate per unit) and the cement are mixed; the remaining steps are the same as those in the seventh embodiment.
[0079] Ninth embodiment
[0080] The conductive cement-based composite material preparation method based on conductive aggregate in this embodiment is different from the seventh embodiment in that, in this embodiment, the fine aggregate, the conductive aggregate (the conductive aggregate replaces 60% of the natural fine aggregate, that is, 810g of the conductive aggregate and 540g of the fine aggregate per unit) and the cement are mixed; the remaining steps are the same as those in the seventh embodiment.
[0081] Tenth embodiment
[0082] The preparation method of the conductive cement-based composite material based on conductive aggregate of the present embodiment is different from that of Embodiment Seven in that, in the present embodiment, fine aggregate and conductive aggregate (the conductive aggregate replaces 40% of the natural fine aggregate, i.e., 540 g of conductive aggregate and 810 g of fine aggregate per unit) are mixed with cement; the remaining steps are the same as those of Embodiment Seven.
[0083] Eleventh Embodiment
[0084] The preparation method of the conductive cement-based composite material based on conductive aggregate of the present embodiment is different from that of Embodiment Seven in that, in the present embodiment, fine aggregate and conductive aggregate (the conductive aggregate replaces 20% of the natural fine aggregate, i.e., 270 g of conductive aggregate and 1080 g of fine aggregate per unit) are mixed with cement; the remaining steps are the same as those of Embodiment Seven.
[0085] Seventh Embodiment
[0086] The preparation method of the conductive cement-based composite material based on conductive aggregate of the present embodiment comprises:
[0087] The water reducing agent and mixing water are pre-mixed for use; then the conductive aggregate (the conductive aggregate completely replaces the natural fine aggregate, i.e., 1350 g of conductive aggregate per unit) is mixed with cement; a water solution containing the water reducing agent is slowly added during stirring, and a conductive cement composite material (water-cement ratio of 0.4) is obtained after 4 minutes of stirring; finally, the mixture is poured into a mold, four parallel copper electrode sheets are inserted, and a conductive cement mortar based on a conductive framework structure design is obtained.
[0088] Thirteenth Embodiment
[0089] The present embodiment is a control group, and provides a cement-based composite material, i.e., a cement-based composite material without the addition of conductive carbon nanotube aggregate, which specifically comprises:
[0090] The water reducing agent and mixing water are pre-mixed for use; then the short carbon fiber (6 mm, mass ratio of short carbon fiber to cement is 5:1000), fine aggregate coated with a polyacrylic resin coating on the surface (completely replaces the natural fine aggregate, i.e., 1350 g per unit) is mixed with cement; a water solution containing the water reducing agent is slowly added during stirring, and a conductive cement composite material (water-cement ratio of 0.4) is obtained after 4 minutes of stirring; finally, the mixture is poured into a mold, and four parallel copper electrode sheets are inserted.
[0091] Fourteenth Embodiment
[0092] The present embodiment is a control group, and the cement-based composite material provided, i.e. the cement-based composite material without adding conductive carbon nanotube aggregate, is different from the twelfth embodiment in that the water reducing agent and mixing water are premixed for use; then the chopped carbon fiber (6 mm, the mass ratio of chopped carbon fiber to cement is 5:1000), natural fine aggregate (1350 g per unit) and cement are mixed; the remaining steps are the same as those of the twelfth embodiment.
[0093] In combination with the above table and the seventh to thirteenth embodiments, the test results are shown in the following table:
[0094]
[0095]
[0096] In combination with the above table, the technical solutions provided by the present application can greatly reduce the resistivity of cement mortar, which is conducive to improving the electrical conductivity of the conductive cement-based composite material. As can be seen from the comparative examples seven to thirteen, the use of conductive aggregate greatly reduces the resistivity of the mortar, and the combined use of the chopped carbon fiber can further reduce the resistivity of the mortar; in addition, the use of the conductive aggregate can also improve the compressive strength and flexural strength of the mortar. Figure 4 (i.e. the self-awareness of the carbon nanotube network in the concrete: (a) conductive aggregate; (b) coating peeling point; (c) carbon nanotube and cement hydration product mixing zone; (d) coating section; (f) CNT on both sides of the crack
[0097] As can be seen, the scanning electron microscope can clearly see the carbon nanotube conductive network existing in the conductive cement mortar prepared in the embodiment. As can be seen from the comparison between the comparative example seven and the thirteenth and fourteenth embodiments, the use of the conductive aggregate can also slightly improve the compressive strength and flexural strength.
[0098] The above is a detailed description of the present application in combination with specific embodiments, which cannot be considered as limiting the specific embodiments of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, some equivalent substitutions or obvious modifications can be made without departing from the concept of the present application, and the performance or use is the same, which should be considered as belonging to the patent protection scope determined by the submitted claims of the present application.
Claims
1. A method for preparing conductive aggregate, characterized in that, Includes the following steps: S1. Take dry fine aggregate and place it in an ultrasonic cleaner for surface cleaning and roughening treatment; S2. To prepare a CNT dispersion, carbon nanotubes are added to ethanol or acetone, and a surfactant is added. The dispersion is then prepared by ultrasonic stirring. S3. Immerse the fine aggregate obtained in step S1 into a polyacrylic acid resin solution, stir at room temperature for 10-60 minutes, heat at 120-200℃ and stir until the coating is dry to obtain fine aggregate with a polyacrylic acid resin adhesive layer on the surface. S4. Immerse the fine aggregate obtained in step S3 into the CNT dispersion prepared in step S2, and stir for 3 to 15 minutes to allow carbon nanotubes to be uniformly adsorbed on the surface of the aggregate. S5. Then control the stirring temperature to 100-200℃, stir continuously at 50-80 rpm for 5-30 minutes, and use a 60-mesh sieve to sieve and wash the coarser solids obtained from the sieve. S6. The coarser solid material obtained in step S5 is dried at 60-90°C for 24-72 hours to form a uniform and dense outer layer of polyacrylic acid resin, thereby obtaining a double-coated conductive aggregate.
2. The method for preparing conductive aggregate according to claim 1, characterized in that: The fine aggregate is natural sand or manufactured sand with a particle size of 0.075 to 4.75 mm and a water absorption rate of less than 2.5%.
3. The method for preparing conductive aggregate according to claim 1, characterized in that: The mass ratio of carbon nanotubes to fine aggregate is 0.1-1%, and the mass ratio of polyacrylic acid resin to fine aggregate is 1-5%.
4. The method for preparing conductive aggregate according to claim 1, characterized in that: The polyacrylic acid resin solution is an aqueous emulsion or diluent with a mass concentration of 5-30%.
5. The method for preparing conductive aggregate according to claim 1, characterized in that: The drying process employs a stepped heating method, including a low-temperature pre-drying stage and a high-temperature curing stage.
6. The method for preparing conductive aggregate according to claim 1, characterized in that: , characterized in that: It is prepared according to any one of claims 1 to 5, wherein the conductive aggregate is coated with an inner carbon nanotube adsorption layer and an outer polyacrylic acid resin coating layer to form a core-shell structure.
7. The method for preparing conductive aggregate according to claim 6, characterized in that: The overall thickness of the coating layer on the conductive aggregate is 5 to 100 μm, and the coating is evenly distributed on the aggregate surface and firmly bonded.
8. An application of a conductive aggregate, characterized in that: The conductive aggregate cement is used to prepare a cement-based conductive composite material, which includes cement, the conductive aggregate as described in claim 6 or 7, water, admixtures and other conventional aggregates, wherein the amount of conductive aggregate is 1 to 10% of the mass of the cementitious material.
9. The application of a conductive aggregate according to claim 8, characterized in that: The conductivity of the cement-based conductive composite material is 10. -2 ~10 -4 S / cm, compressive strength greater than 30MPa, resistivity stability within ±5%.