Preparation method of functional ceramsite, high-zt-value concrete and preparation method thereof

Abstract

The application relates to a preparation method of functional ceramsite, high-ZT-value concrete and a preparation method thereof. Hematite in high-iron fly ash is reduced into magnetite, high-magnetic fly ash with high iron content is screened through magnetic separation, and the high-magnetic fly ash is sintered into functional ceramsite with high magnetite content in an inert atmosphere; the obtained functional ceramsite is used for preparing high-ZT-value structure-function integrated concrete, and the concrete is prepared according to the mass fraction ratio of 200-220 parts of cement, 60-70 parts of low-magnetic fly ash, 90-100 parts of mineral powder, 850-880 parts of functional ceramsite, 1200-1400 parts of magnetite sand, 0.4-1 part of conductive polyaniline-carbon nanotube composite material, 4-6 parts of water reducing agent and 160-170 parts of water. The high-ZT-value structure-function integrated concrete material is simple, has high thermoelectric coefficient and electric conductivity and low thermal conductivity under the premise of not affecting the mechanical property, has high thermoelectric conversion efficiency, has high ZT value, and overcomes the problem that high-ZT-value concrete is difficult to prepare in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building materials, in particular to a preparation method of functional ceramsite, high ZT value concrete and a preparation method thereof. BACKGROUND

[0002] ZT value is a coefficient for comprehensively measuring the performance of thermoelectric materials, and the larger the ZT value of the thermoelectric material is, the better the thermoelectric performance of the material is. In the prior art, when preparing high ZT value functional concrete, carbon fibers, carbon nanotubes, graphite, carbon black and other non-metallic materials are generally added to the cement paste, or steel fibers, steel slag and other metal materials are added, but due to the limited volume ratio of the cement paste in the concrete, the addition amount of the metal or non-metal functional materials is also very limited, and if the addition amount of these functional materials is increased, the mechanical properties of the concrete will be greatly reduced. In addition, the aggregate which occupies a large volume ratio in the concrete does not have corresponding functions, and even blocks the path of the functional phase in the cement paste. In addition, in order to achieve a high ZT value, a high thermoelectric coefficient, a high electrical conductivity and a low thermal conductivity are required, and the three will affect each other, so it is difficult to prepare functional concrete with a high ZT value. SUMMARY

[0003] In order to solve the problem that the high ZT of the concrete is difficult to achieve in the prior art, the present application provides a preparation method of functional ceramsite, high ZT value concrete and a preparation method thereof, which gives the aggregate which occupies a large volume ratio in the concrete with corresponding functions, the cylinder compressive strength of the prepared functional ceramsite is high, and the Seebeck effect is strong, the functional ceramsite and the functional cement paste are synergistically used to improve the related performance of the concrete, so as to realize the preparation of the high ZT value concrete.

[0004] The technical purpose of the present application is realized by the following technical scheme:

[0005] A preparation method of functional ceramsite comprises the following steps:

[0006] S1, high-iron fly ash containing magnetite and hematite is placed in a calcination furnace, and is calcined at a calcination temperature of 800 DEG C for 30 min to obtain calcined fly ash A, and the calcined fly ash A contains magnetite;

[0007] S2, the calcined fly ash A is dispersed in water to obtain a calcined fly ash solution B, the magnetic substances in the calcined fly ash solution B are separated out to obtain wet high-magnetic fly ash C and low-magnetic fly ash solution D;

[0008] S3, the wet high-magnetic fly ash C is dried to constant weight to obtain high-magnetic fly ash, and the low-magnetic fly ash solution D is dried to constant weight to obtain low-magnetic fly ash;

[0009] S4, the high-magnetic fly ash is granulated to form functional ceramsite green balls E;

[0010] S5. Calcination of functional ceramsite pellets E under an inert atmosphere, including three stages:

[0011] The first stage involves a preheating temperature of 400℃ and a preheating time of 30 minutes.

[0012] The second stage involves sintering at 1100℃ for 20 minutes.

[0013] The third stage involves rapid cooling for 15 minutes until the temperature drops to room temperature, yielding coarse functional ceramsite F.

[0014] S6. The coarse functional ceramsite F is sieved to obtain functional ceramsite with an apparent density of 2000–2300 kg / m³. 3 The compressive strength of the cylinder is 6-10 MPa, and the particle size is 5-20 mm.

[0015] Furthermore, the high-speed iron fly ash contains 14%–20% Fe2O3, 45%–54% SiO2, 25%–30% Al2O3, 0.5%–1% Na2O, 0.5%–1% K2O, 1%–4% CaO, 0.5%–3% MgO, and 4%–6% residual carbon.

[0016] Furthermore, the mass ratio of roasted fly ash A to water is 1:9 to 1:4.

[0017] Furthermore, the Fe2O3 content in high-magnetic fly ash is 45%–60%, while the Fe2O3 content in low-magnetic fly ash is 2%–6%.

[0018] This invention also provides a high ZT value structural-functional integrated concrete, comprising, by mass ratio: 200-220 parts cement, 60-70 parts low-magnetic fly ash, 90-100 parts mineral powder, 850-880 parts functional ceramsite, 1200-1400 parts magnetite sand, 0.4-1 parts conductive polyaniline-carbon nanotube composite material, 4-6 parts water-reducing agent, and 160-170 parts water. The low-magnetic fly ash and functional ceramsite are prepared by the above-described method for preparing functional ceramsite. The conductive polyaniline-carbon nanotube composite material is prepared by polymerizing aniline onto carbon nanotubes using ammonium persulfate as an initiator.

[0019] Furthermore, the particle size of the magnetite sand is 315μm to 2.50mm.

[0020] Furthermore, the water-reducing agent is a high-performance polycarboxylate water-reducing agent.

[0021] This invention also provides a method for preparing high ZT value structural-functional integrated concrete, the method comprising:

[0022] S1. Take 850-880 parts of functional ceramsite, soak it in water for 24 hours, and weigh it to determine the water absorption of the functional ceramsite.

[0023] S2. Prepare conductive polyaniline-carbon nanotube composite material. Take 0.4 to 1 part of the conductive polyaniline-carbon nanotube composite material by mass fraction and ultrasonically disperse it in 20 to 40 parts of water for 30 to 60 minutes to obtain ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K, for later use.

[0024] S3. Take 200-220 parts of cement, 60-70 parts of low magnetic fly ash, 90-100 parts of mineral powder, 850-880 parts of water-absorbing functional ceramsite, and 1200-1400 parts of magnetite sand and mix them evenly to obtain dry material I.

[0025] S4. Take 4 to 6 parts of the water-reducing agent, pour it into the remaining water and stir evenly. Add it to dry material I and mix evenly to obtain slurry J.

[0026] S5. Add the ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K to the slurry J and stir evenly to obtain high ZT value structural and functional integrated concrete.

[0027] Furthermore, the preparation method of the conductive polyaniline-carbon nanotube composite material in step S2 includes:

[0028] S21. Disperse carbon nanotubes ultrasonically in a 0.5 mol / L H2SO4 solution at a ratio of 1 g / 40 ml.

[0029] S22. Add aniline to the solution obtained in step S21 at a ratio of 1g / 20ml and stir for 30min;

[0030] S23. Add 0.025 mol / L ammonium persulfate solution to the solution obtained in step S22 at a volume ratio of 1:10, and stir in an ice bath for 3 hours.

[0031] S24. The product obtained in step S23 is filtered, washed, and dried to obtain a conductive polyaniline-carbon nanotube composite material.

[0032] Furthermore, in step S21, the carbon nanotubes have a purity >95wt%, an inner diameter of 3-5nm, an outer diameter of 8-15nm, a length of 3-12μm, and a specific surface area >233㎡ / g.

[0033] Furthermore, in step S22, the aniline is analytical grade aniline.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. The high ZT value structural-functional integrated concrete of this invention achieves functional synergy between aggregates and cement paste, functional synergy between inorganic and organic materials, and functional synergy between metal oxides and non-metallic carbon-based materials. The functional ceramsite, used as coarse aggregate, contains a large amount of magnetite and is combined with fine aggregate magnetite sand, resulting in high thermoelectric coefficients and high electrical conductivity. The conductive polyaniline-carbon nanotube composite material added to the cement paste leverages the low thermal conductivity of high-molecular organic polymers and fully utilizes the excellent semiconductor and thermoelectric properties of carbon-based nanomaterials, resulting in concrete with high thermoelectric coefficients, high electrical conductivity, and low thermal conductivity, thus achieving a high ZT value.

[0036] 2. This invention utilizes ammonium persulfate to initiate the in-situ polymerization of aniline onto carbon nanotubes, forming a conductive polyaniline-carbon nanotube composite material. Addressing the difficulty in dispersion, it employs a combination of ultrasonic dispersion and a dispersant to ensure uniform dispersion of carbon nanotubes within the cement paste. The polycarboxylate superplasticizer functions as a conventional superplasticizer and, being an anionic surfactant, further promotes the dispersion of carbon nanotubes.

[0037] 3. This invention selects fly ash with high iron content and uses a reduction-magnetic separation-inert atmosphere sintering process to reduce the hematite in high-iron fly ash to strongly magnetic magnetite by the residual carbon in the fly ash. No additional reducing agent is needed. During the sintering process of the ceramsite, the magnetite is prevented from being sintered into hematite or elemental iron by the protection of an inert atmosphere. As a result, the functional ceramsite obtained by sintering contains a large amount of magnetite, which improves the thermoelectric properties of the coarse aggregate.

[0038] 4. This invention improves both the strength of the cement paste and the functionality of the ceramsite by transferring iron, which is detrimental to the mechanical properties of concrete, from the fly ash into the ceramsite. On one hand, the low-magnetic fly ash in the cement paste removes most of the iron oxides, reducing the iron content and increasing the content of active silica and aluminum substances, thereby enhancing the pozzolanic activity of the fly ash and thus increasing the strength of the concrete. On the other hand, the functional ceramsite has a higher magnetite content, improving its thermoelectric properties and thus enhancing the functionality of the prepared concrete. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0040] Example 1

[0041] 1. A method for preparing functional ceramsite, characterized in that it comprises:

[0042] S1. High-iron fly ash containing magnetite and hematite is placed in a roasting furnace and roasted at 800℃ for 30 minutes to obtain roasted fly ash A, which contains magnetite.

[0043] Among them, the content of Fe2O3 in high-speed iron fly ash is 14% to 20%, the content of SiO2 is 45% to 54%, the content of Al2O is 25% to 30%, the content of Na2O is 0.5% to 1%, the content of K2O is 0.5% to 1%, the content of CaO is 1% to 4%, the content of MgO is 0.5% to 3%, and the content of residual carbon is 4% to 6%.

[0044] In this stage, the hematite in high-speed fly ash A undergoes a reduction reaction at high temperature. The reaction process is as follows:

[0045] 2C + O2 = 2CO

[0046] 3Fe₂O₃ + CO = 2Fe₃O₄ + CO₂

[0047] S2. Disperse calcined fly ash A in water at a mass ratio of 1:9 to 1:4. In this embodiment, the mass ratio of calcined fly ash A to water is 1:5 to obtain calcined fly ash solution B. Separate the magnetic substances from calcined fly ash solution B to obtain wet high-magnetic fly ash C and low-magnetic fly ash solution D.

[0048] More specifically, the process of separating magnetic materials is as follows:

[0049] Step S21: Stir the calcined fly ash solution B with a magnetic rod with a magnetic induction intensity of 1T, so that the magnetic material in the calcined fly ash solution B is adsorbed on the surface of the magnetic rod, and collect the magnetic material on the surface of the magnetic rod for later use; repeat the above process until the surface of the magnetic rod with a magnetic induction intensity of 1T no longer has magnetic material adsorbed.

[0050] Step S22: Stir the calcined fly ash solution B after the above step S21 by using a magnetic rod with a magnetic induction intensity of 1.2T, so that the magnetic material in the calcined fly ash solution B is adsorbed on the surface of the magnetic rod with a magnetic induction intensity of 1.2T. Collect the magnetic material on the surface of the magnetic rod with a magnetic induction intensity of 1.2T for later use. Repeat the operation until the surface of the magnetic rod with a magnetic induction intensity of 1.2T no longer has magnetic material adsorbed.

[0051] Step S23: Mix the collected magnetic materials to obtain wet high-magnetic fly ash C, and process the calcined fly ash solution B through step S22 to obtain low-magnetic fly ash solution D.

[0052] S3. Dry the wet high-magnetic fly ash C to constant weight to obtain high-magnetic fly ash; dry the low-magnetic fly ash solution D to constant weight to obtain low-magnetic fly ash; during drying, use an oven to dry at a temperature of 60℃.

[0053] More specifically, the Fe2O3 content in high-magnetic fly ash is 45%–60%, while the Fe2O3 content in low-magnetic fly ash is 2%–6%.

[0054] S4. Granulate high-magnetic fly ash to form functional ceramsite green pellets E. During granulation, the high-magnetic fly ash is placed on the disc of a disc pelletizing machine. Water is sprayed while the disc is rotated horizontally until the high-magnetic fly ash rolls into a ball shape on the disc. After drying, functional ceramsite green pellets E are obtained.

[0055] S5. Calcination of functional ceramic pellets E under argon protection includes three stages:

[0056] The first stage involves a preheating temperature of 400℃ and a preheating time of 30 minutes.

[0057] The second stage involves sintering at 1100℃ for 20 minutes.

[0058] The third stage involves rapid cooling for 15 minutes until the temperature drops to room temperature, yielding coarse functional ceramsite F.

[0059] During the sintering process described above, argon gas, as an inert atmosphere, prevents the magnetite in the functional ceramic pellets E from being reduced or oxidized, thus ensuring that a large amount of magnetite is retained in the ceramic pellets after sintering.

[0060] S6. The coarse functional ceramsite F is sieved to obtain functional ceramsite with an apparent density of 2000–2300 kg / m³. 3 The compressive strength of the cylinder is 6-10 MPa, and the particle size is 5-20 mm.

[0061] Example 2

[0062] A high ZT value structural-functional integrated concrete comprises, by weight, 215 parts cement, 62 parts low-magnetic fly ash, 93 parts mineral powder, 862 parts functional ceramsite, 1326 parts magnetite sand, 0.7 parts conductive polyaniline-carbon nanotube composite material, 5 parts water-reducing agent, and 165 parts water. The low-magnetic fly ash and functional ceramsite are prepared using the method of Example 1. The conductive polyaniline-carbon nanotube composite material is prepared by polymerizing aniline onto carbon nanotubes using ammonium persulfate as an initiator. The magnetite sand has a particle size of 315 μm to 2.50 mm, and the water-reducing agent is a high-performance polycarboxylate superplasticizer.

[0063] The preparation process of the above-mentioned high ZT value structural-functional integrated concrete is as follows:

[0064] S1. Take 862 portions of functional ceramsite, soak them in water for 24 hours, and weigh them to determine the water absorption of the functional ceramsite.

[0065] S2. Prepare conductive polyaniline-carbon nanotube composite material. Take 0.7 parts of conductive polyaniline-carbon nanotube composite material by mass fraction and ultrasonically disperse it in 30 parts of water for 30 min to obtain ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K, for later use.

[0066] S3. Take 215 parts of cement, 62 parts of low magnetic fly ash, 93 parts of mineral powder, 862 parts of water-absorbing functional ceramsite, and 1326 parts of magnetite sand and mix them evenly to obtain dry material I.

[0067] S4. After deducting the water absorption of the functional ceramic particles and the water used in the ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K, the remaining water is 5 parts of the water-reducing agent. Pour it into the remaining water and stir evenly. Add it to the dry material I and stir evenly to obtain slurry J.

[0068] S5. Add the ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K to the slurry J and stir evenly to obtain high ZT value structural and functional integrated concrete.

[0069] More specifically, the preparation method of the conductive polyaniline-carbon nanotube composite material in step S2 includes:

[0070] S21. Carbon nanotubes were ultrasonically dispersed in a 0.5 mol / L H2SO4 solution at a ratio of 1 g / 40 ml. The H2SO4 solution provided an acidic environment for the subsequent process.

[0071] Among them, the carbon nanotubes have a purity of >95wt%, an inner diameter of 3-5nm, an outer diameter of 8-15nm, a length of 3-12μm, and a specific surface area of ​​>233㎡ / g.

[0072] S22. Add aniline to the solution obtained in step S21 at a ratio of 1g / 20ml and stir for 30min. The aniline is analytical grade aniline.

[0073] S23. Add 0.025 mol / L ammonium persulfate solution to the solution obtained in step S22 at a volume ratio of 1:10, and stir in an ice bath for 3 hours. Ammonium persulfate oxidizes aniline, which undergoes in-situ polymerization under acidic conditions of H2SO4 solution to generate polyaniline. Polyaniline polymerizes on the surface of carbon nanotubes.

[0074] S24. The product obtained in step S23 is filtered, washed, and dried to obtain a conductive polyaniline-carbon nanotube composite material.

[0075] The high ZT value structural-functional integrated concrete prepared by the method in Example 2 above was subjected to compressive strength and ZT value tests. The test results are shown in the table below:

[0076] Test item Compressive strength (MPa) ZT value Example 2 38.5 4.02×10

[0077] The test results in the table above show that the high ZT value structural-functional integrated concrete prepared in Example 2 has high compressive strength and high ZT value. The functional ceramsite, used as coarse aggregate, contains magnetite, and the magnetite sand, used as fine aggregate, works synergistically with the conductive polyaniline-carbon nanotube composite material in the cement paste, thereby increasing the ZT value and the thermoelectric conversion efficiency of the concrete.

[0078] In the prior art, the ZT value needs to be calculated comprehensively, as shown below:

[0079]

[0080] In the above formula, k is thermal conductivity, σ is electrical conductivity, S is the Seebeck coefficient, and T is absolute temperature.

[0081] It should be noted that the letters in the following terms in this application—calcined fly ash A, calcined fly ash solution B, wet high-magnetic fly ash C, low-magnetic fly ash solution D, functional ceramsite pellets E, coarse functional ceramsite F, dry material I, slurry J, and ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K—have no special limiting meaning and are only used to distinguish substances and materials.

[0082] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A high ZT value structural-functional integrated concrete, characterized in that, The composition comprises, by weight, 200-220 parts cement, 60-70 parts low-magnetic fly ash, 90-100 parts mineral powder, 850-880 parts functional ceramsite, 1200-1400 parts magnetite sand, 0.4-1 parts conductive polyaniline-carbon nanotube composite material, 4-6 parts water-reducing agent, and 160-170 parts water. The conductive polyaniline-carbon nanotube composite material is prepared by polymerizing aniline onto carbon nanotubes using ammonium persulfate as an initiator. The low-magnetic fly ash and functional ceramsite are prepared by the following method, which includes: S1. High-iron fly ash containing magnetite and hematite is placed in a roasting furnace, wherein the high-iron fly ash contains... The content is 14%~20%. The content is 45%~54%. The content is 25%~30%. The content is 0.5%~1%. The content of MgO is 0.5%~1%, the content of CaO is 1%~4%, the content of MgO is 0.5%~3%, and the content of residual carbon is 4%~6%. Roasted fly ash A is obtained by roasting at 800℃ for 30 minutes. Roasted fly ash A contains magnetite. S2. Disperse calcined fly ash A in water to obtain calcined fly ash solution B. Separate the magnetic substances from calcined fly ash solution B to obtain wet high-magnetic fly ash C and low-magnetic fly ash solution D. S3. Dry the wet high-magnetic fly ash C to constant weight to obtain high-magnetic fly ash, wherein the high-magnetic fly ash contains... The content is 45%~60%; the low magnetic fly ash solution D is dried to constant weight to obtain low magnetic fly ash, wherein the low magnetic fly ash contains... The content is 2%~6%; S4. Granulate high magnetic fly ash to form functional ceramic pellets E; S5. Calcination of functional ceramsite pellets E under an inert atmosphere, including three stages: The first stage involves a preheating temperature of 400℃ and a preheating time of 30 minutes. The second stage involves sintering at 1100℃ for 20 minutes. The third stage involves rapid cooling for 15 minutes until the temperature drops to room temperature, yielding coarse functional ceramsite F. S6. The coarse functional ceramsite F is sieved to obtain functional ceramsite. The apparent density of the functional ceramsite is 2000~2300kg / m³, the compressive strength is 6~10MPa, and the particle size is 5~20mm.

2. The high ZT value structural-functional integrated concrete according to claim 1, characterized in that, The mass ratio of the roasted fly ash A to water is 1:9 to 1:

4.

3. The high ZT value structural-functional integrated concrete according to claim 1, characterized in that, The magnetite sand has a particle size of 315μm to 2.50mm.

4. The high ZT value structural-functional integrated concrete according to claim 1, characterized in that, The water-reducing agent is a high-performance polycarboxylate water-reducing agent.

5. A method for preparing high ZT value structural-functional integrated concrete as described in claim 1, characterized in that, The method includes: S1. Take 850-880 parts of functional ceramsite, soak it in water for 24 hours, and weigh it to determine the water absorption of the functional ceramsite. S2. Prepare conductive polyaniline-carbon nanotube composite material. Take 0.4~1 parts of conductive polyaniline-carbon nanotube composite material by mass ratio and ultrasonically disperse it in 20~40 parts of water for 30~60 min to obtain ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K, for later use. S3. Take 200-220 parts of cement, 60-70 parts of low magnetic fly ash, 90-100 parts of mineral powder, 850-880 parts of water-absorbing functional ceramsite, and 1200-1400 parts of magnetite sand and mix them evenly to obtain dry material I. S4. Take 4-6 parts of the water-reducing agent, pour it into the remaining water and stir evenly. Add it to dry material I and mix evenly to obtain slurry J. S5. Add the ultrasonically dispersed conductive polyaniline-carbon nanotube mixture K to the slurry J and stir evenly to obtain high ZT value structural and functional integrated concrete.

6. The method for preparing high ZT value structural-functional integrated concrete according to claim 5, characterized in that, The preparation method of the conductive polyaniline-carbon nanotube composite material in step S2 includes: S21. Disperse carbon nanotubes ultrasonically in 0.5 mol / L solution at a ratio of 1 g / 40 ml. in solution; S22. Add aniline to the solution obtained in step S21 at a ratio of 1g / 20ml and stir for 30min; S23. Add 0.025 mol / L ammonium persulfate solution to the solution obtained in step S22 at a volume ratio of 1:10, and stir in an ice bath for 3 hours. S24. The product obtained in step S23 is filtered, washed, and dried to obtain a conductive polyaniline-carbon nanotube composite material.

7. The method for preparing high ZT value structural-functional integrated concrete according to claim 6, characterized in that, In step S21, the carbon nanotubes have a purity > 95 wt%, an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, a length of 3-12 μm, and a specific surface area > 233 m² / g.

8. The method for preparing high ZT value structural-functional integrated concrete according to claim 6, characterized in that, In step S22, the aniline is analytical grade aniline.

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