A biochar-based carbon-negative functional cement particle board and a preparation method thereof

Abstract

The application discloses a kind of biochar-based carbon-negative functional cement particle board and preparation method thereof, the preparation method includes that biomass is pyrolyzed at 400~600 ℃, broken, screening to obtain biochar;Biochar, Portland cement, mineral admixture are uniformly mixed, stirring to obtain mixed dry material according to the proportion of mass ratio (40-60):(28-42):(12-18);Water is added to mixed dry material, and stirring is uniformly obtained slurry;Part of slurry is placed into mould, then basalt grid fiber is added, then another part of slurry is added to cover the basalt grid fiber, surface is vibrated and flattened, and after pressing, the blank of plate is demoulded;The blank of plate is first carbonized and cured by CO2, and then standard curing is carried out to obtain biochar-based carbon-negative functional cement particle board.The cement particle board prepared by the method is light weight, high strength and has good durability, and also has high heat preservation, sound absorption and noise reduction and carbon-negative property.

Description

Technical Field

[0001] This invention belongs to the technical field of solid waste recycling and cement particleboard preparation, specifically relating to a biochar-based negative carbon functional cement particleboard and its preparation method. Background Technology

[0002] In today's vigorous promotion of low-carbon, green, and circular development, the unique characteristics and advantages of using biomass to replace or combine with traditional building materials to form "sustainable biomass composite building materials" are becoming increasingly important and urgent in the future development of the building materials industry.

[0003] Cement particleboard is one of the most commonly used engineered wood products. It is typically made by mixing cement as a binder, wood shavings as a reinforcing filler, and adding appropriate amounts of water and additives, followed by pressing, molding, and curing processes. Compared to traditional wood-based panels, it boasts advantages such as high strength, fire resistance, insect resistance, and zero formaldehyde, making it widely applicable in wall materials, interior and exterior decoration, and furniture manufacturing.

[0004] Chinese patent application CN100387414C discloses a method for producing lightweight cement particleboard. The process involves: selecting 1.0 part by weight of wood shavings (oven-dried) with a length >30 mm, 0-0.5 parts of filler (oven-dried), 0.5-3 parts of cement, 0.02-0.24 parts of additives, and 1.0-2.0 parts of water, mixing (spraying) until uniform, laying into a board blank, cold-pressing at a pressure of 0.2-1 MPa for 20-40 hours, and then naturally curing the formed board at room temperature. This lightweight cement particleboard is widely used in earthquake-resistant buildings, broadcasting studios, and interior ceilings. However, the wood shavings in the lightweight cement particleboard are easily corroded, affecting its durability.

[0005] The filler in cement particleboard is generally made of wood. However, the soluble organic matter in wood can severely inhibit the hydration reaction of cement, affecting the mechanical properties of the particleboard. Furthermore, the cellulose and lignin in wood will slowly degrade in the long-term high-alkalinity environment of cement, impacting the durability of the particleboard. Therefore, it is necessary to develop and utilize other highly durable biomass materials to replace wood in the application of cement particleboard.

[0006] Biochar is a porous, stable material obtained from various biomass through thermochemical transformation in an oxygen-deficient environment. Biomass sources are widespread, including forestry waste, agricultural waste, organic sludge, and livestock manure. Biochar possesses a tunable pore structure, abundant functional groups, and active apparent interfacial reactions, and has been widely applied in soil remediation, wastewater treatment, and catalytic reactions. Recent studies have found that porous biochar can serve as a green additive for cement-based composite materials, promoting cement hydration and improving the mechanical properties of building materials through its water retention capacity and internal curing effect.

[0007] Patent application CN110238932A discloses a high-strength, mildew-resistant, and corrosion-resistant cement particleboard and its preparation method. The preparation method includes the following steps: (1) carbonizing and washing the wood shavings sequentially, then mixing the carbonized wood shavings with a cement binder, a curing agent aqueous solution, and water to obtain a mixture; (2) molding the mixture to obtain a preform; and (3) curing and drying the preform to obtain the mildew-resistant, corrosion-resistant, and high-strength cement particleboard. Compared to ordinary cement particleboard without carbonization and washing, the cement particleboard prepared by this method effectively avoids mildew and decay, and significantly improves its mechanical strength and durability, thus extending its service life. However, the carbonization temperature disclosed in this patent application is relatively low, and the wood shavings are not completely converted into biochar. The carbonized wood shavings only provide mildew and corrosion protection, offering little benefit to insulation, noise reduction, or other properties. Summary of the Invention

[0008] This invention provides a method for preparing biochar-based negative carbon functional cement particleboard. The cement particleboard prepared by this method is lightweight, high-strength, and has good durability, while also having high thermal insulation, sound absorption and noise reduction properties, and negative carbon properties.

[0009] This invention provides a method for preparing biochar-based negative carbon functional cement particleboard, comprising:

[0010] Biochar is obtained by pyrolyzing, crushing, and sieving biomass at 400-600℃.

[0011] The biochar, silicate cement, and mineral admixtures are uniformly mixed and stirred in a mass ratio of (40-60):(28-42):(12-18) to obtain a mixed dry material;

[0012] Add water to the mixed dry materials and stir until a slurry is obtained;

[0013] After some of the slurry is put into the mold, basalt grid fibers are added, and then another part of the slurry is added to cover the basalt grid fibers. The surface is vibrated and flattened, and after pressure is applied, the mold is demolded to obtain the plate blank.

[0014] The board blank is first subjected to CO2 carbonization curing, and then subjected to standard curing to obtain biochar-based negative carbon functional cement particleboard.

[0015] Preferably, the biomass is bamboo, wood, or straw.

[0016] Preferably, the pyrolysis conditions are as follows: in a CO2 atmosphere of 200±10 mL / min, the temperature is increased to 400~600℃ at a rate of 10±1℃ / min, and pyrolysis is performed for 90~150 minutes. A suitable pyrolysis time can provide sufficient energy to carbonize the biomass and form a porous structure.

[0017] Preferably, the size of the sieved biochar is 0~5mm, excluding the end point 0.

[0018] Preferably, before mixing the biochar, the biochar is pre-soaked in water for 12-15 hours and then drained to obtain saturated surface drying conditions, which improves the workability when mixed with cement. The silicate cement and mineral admixtures need to be dried to constant weight in an oven at 105±1℃ before mixing.

[0019] Preferably, the mineral admixture is an industrial waste rich in active components such as calcium, silicon, and aluminum, such as granulated blast furnace slag or fly ash, and the silicate cement is designated as PI42.5.

[0020] Preferably, the mass ratio of water to the mixture of silicate cement and mineral admixtures is 0.38 to 0.42 to ensure that the cementitious material can undergo a full hydration reaction, bind the wood shavings, and provide strong mechanical properties.

[0021] Preferably, the basalt grid fibers are in a mesh shape, and are added to the slurry at a mass ratio of 1% to 3% of the mixed dry materials to improve the mechanical properties of the cement particleboard. The amount of basalt grid fibers added should not be excessive, otherwise it will lead to a decrease in cementitious properties and the formation of cracks.

[0022] Preferably, the pressure for the pressurization molding is 4~6MPa, and the pressurization time is 3~5 minutes, until the sheet blank has no springback, and then the sheet blank is demolded.

[0023] Preferably, the parameters for CO2 carbonization curing are: temperature 20℃±2℃, relative humidity 75%±5%, pressure 1MPa±0.1MPa, and CO2 with a purity of 99% is introduced; the operating conditions in the standard curing chamber are: temperature 20℃±2℃, relative humidity 95%±5%, and normal pressure.

[0024] The present invention also provides a biochar-based negative carbon functional cement particleboard, which is prepared by the preparation method of the biochar-based negative carbon functional cement particleboard.

[0025] Preferably, the biochar-based cement particleboard was tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusivity of Building Materials", and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The tested particleboard had a moisture content of 8%~12%, a 24-hour thickness expansion rate ≤2%, a static bending strength of 9~12.5 MPa, no through-cracks in the impact resistance test, and a density of 900~1250 kg / m³. 3 It has a thermal conductivity of 0.25~0.45W / (m·K), a noise reduction factor (NRC) ≥0.4, and a negative carbon footprint throughout its entire life cycle.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention utilizes high-temperature pyrolysis of waste biomass to obtain biochar with low bulk density, low thermal conductivity, and abundant pore structure. By adding a high content of the biochar, the cement particleboard provided by this invention has the properties of being lightweight, corrosion-resistant, heat-insulating, and sound-absorbing. At the same time, combined with CO2 carbonization curing, it greatly reduces the carbon emissions of cement particleboard, realizing the development of negative carbon cement particleboard.

[0028] This invention controls the proportion of biochar incorporation and enhances the mechanical properties of cement particleboard by adding basalt grid fibers and using CO2 carbonization curing. As a result, the cement particleboard provided by this invention not only meets the standard requirements but also has special functionalities such as lightweight carbon negative, heat insulation, and noise reduction. Attached Figure Description

[0029] Figure 1 A flowchart illustrating the preparation method of biochar-based negative carbon functional cement particleboard provided in a specific embodiment of the present invention. Detailed Implementation

[0030] This invention provides a biochar-based negative carbon functional cement particleboard and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0031] The biochar in this invention is a porous and stable material obtained from various biomass through thermochemical transformation in an oxygen-deficient environment. Biomass sources are widely available, including forestry waste, agricultural waste, organic sludge, and livestock manure. Biochar possesses a tunable pore structure, abundant functional groups, and active apparent interfacial reactions, and has been widely used in soil remediation, wastewater treatment, and catalytic reactions. Recent studies have found that porous biochar can serve as a green additive for cement-based composite materials, promoting cement hydration and improving the mechanical properties of building materials through its water retention capacity and internal curing effect. Therefore, using stable and widely available biochar to replace traditional wood shavings not only eliminates dependence on traditional wood shavings but also enhances the durability and mechanical properties of cement particleboard. Simultaneously, the low bulk density, low thermal conductivity, and abundant pore structure of biochar can endow biochar-based cement particleboard with special functionalities such as lightweight, heat insulation, and noise reduction. The low bulk density of cement particleboard reduces its overall density, making it lighter and easier to transport, thus meeting the requirements of prefabricated buildings. Its low thermal conductivity and porous structure disrupt internal thermal bridges, inducing heat dispersion and enhancing its thermal insulation properties. Furthermore, the porous structure of biochar creates interconnected pores within the building material, allowing sound waves to refract and dissipate as heat, thereby improving the sound insulation and noise reduction performance of cement particleboard.

[0032] The carbon footprint of biochar over its entire life cycle is -2.0 to -2.6 kg CO2 / kg. Using it as wood shavings can significantly reduce the carbon emissions of cement particleboard. CO2 carbonization curing technology is a commonly used carbon fixation and building material curing technology. Through the mineralization reaction between high-partial-pressure CO2 gas and the cementitious components and other alkaline calcium and magnesium components in the pre-cured building materials, stable carbonate products are formed in the internal pores and interface structure of the building materials, thereby achieving CO2 fixation. Through the filling effect, interface transition period elimination effect, and product layer effect, the strength and durability of building materials can be significantly improved.

[0033] In a specific embodiment of the present invention, bamboo biochar is prepared by pyrolysis of waste bamboo materials such as discarded disposable bamboo chopsticks, discarded bamboo frames, and scraps from bamboo processing plants. Biochar-based cement particleboard is then made from raw materials such as biochar, silicate cement, and mineral admixtures (mineral powder, fly ash, etc.) through cold pressing and CO2 carbonization curing technology.

[0034] The biochar-based particleboard proposed in this invention uses biochar prepared from waste bamboo to replace traditional particleboard, eliminating dependence on traditional wood and avoiding the poor durability of traditional biomass building materials. This invention also partially replaces silicate cement with granulated blast furnace slag, fly ash, and other industrial waste, achieving resource utilization of waste and reducing the production cost and carbon emissions of cement particleboard. Furthermore, this invention utilizes the "negative carbon" properties of biochar and the dual carbon-fixing effect of CO2 carbonization curing to develop negative carbon cement particleboard, contributing to the sustainable development of the construction industry and carbon reduction efforts. In addition, thanks to the excellent properties of biochar, the biochar-based cement particleboard developed in this invention also possesses lightweight, high strength, thermal insulation, and sound absorption properties, meeting the increasingly diversified needs of the building materials market.

[0035] This invention provides a method for preparing biochar-based negative carbon functional cement particleboard by using biochar obtained from the pyrolysis of waste bamboo to replace traditional wood shavings, using silicate cement and mineral admixtures as binders, and incorporating basalt grid fibers to improve mechanical properties, through cold pressing and CO2 carbonization curing technology. Figure 1 As shown in Table 1, the raw material formulations for each embodiment and comparative example are as follows.

[0036] To prevent the raw materials from becoming damp and clumping, which would lead to uneven mixing, silicate cement and mineral admixtures need to be pre-dried before mixing to keep them in a uniform powder state.

[0037] Example 1: A method for preparing biochar-based negative carbon functional cement particleboard, the specific steps of which are as follows:

[0038] (1) Collected waste bamboo materials (discarded disposable bamboo chopsticks, discarded bamboo frames, scraps from bamboo processing plants, etc.) are dried to constant weight in an oven at 105℃, and then sent to a tube furnace at 500℃ for pyrolysis in a CO2 atmosphere at 200 mL / min for 120 minutes to prepare bamboo charcoal. The heating rate of the pyrolysis furnace is 10℃ / min. After cooling to room temperature, the bamboo charcoal is taken out, crushed and screened to separate bamboo charcoal of 0~5 mm for use in the preparation of particleboard;

[0039] (2) Bamboo charcoal, silicate cement (PI42.5), and granulated blast furnace slag (main components include 35.7% CaO, 27.2% SiO2, 12.4% Al2O3, etc.) are mixed evenly in a mass ratio of 40:42:18 and stirred at 300 rpm for 5 minutes to obtain a mixed dry material; the bamboo charcoal needs to be pre-soaked in water for 12 hours before mixing and then drained to obtain saturated surface drying conditions; the silicate cement and mineral admixtures need to be dried in an oven at 105℃ to constant weight before mixing;

[0040] (3) Weigh the required water according to the mass ratio of water:(silicate cement + granulated blast furnace slag)=4:10, then weigh a portion of the mixed dry material, mix the water with the portion of mixed dry material, and stir at 500 rpm for 5 minutes to obtain fresh slurry;

[0041] (4) Weigh an appropriate amount of fresh slurry and divide it into two equal parts. First, pour half of the slurry into the steel mold, vibrate and flatten the surface, then put in basalt grid fiber with a mass ratio of 1% of the mixed dry material, and then pour the other half of the slurry into the mold to cover the basalt grid fiber, and vibrate and flatten the surface.

[0042] (5) Place the steel mold in the cold press and press it for 5 minutes under a pressure of 5MPa until the board has no springback. Then demold the board and put it into a CO2 carbonization curing box (temperature 20℃±2℃, relative humidity 75%±5%, pressure 1MPa±0.1MPa, CO2 with a purity of 99%) for curing for 1 day. Then transfer it to a standard curing box (temperature 20℃±2℃, relative humidity 95%±5%, normal pressure) for curing for 6 days to obtain the finished biochar-based cement particleboard.

[0043] The performance of biochar-based cement particleboard was tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusivity of Building Materials" and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The test results are shown in Table 2.

[0044] Example 2: A method for preparing biochar-based negative carbon functional cement particleboard, the specific steps of which are as follows:

[0045] (1) Collected waste bamboo materials (discarded disposable bamboo chopsticks, discarded bamboo frames, bamboo processing plant scraps, etc.) are dried to constant weight in an oven at 105℃, and then sent to a tube furnace at 500℃ for pyrolysis in a CO2 atmosphere at 200mL / min for 120 minutes to prepare bamboo charcoal. The heating rate of the pyrolysis furnace is 10℃ / min. After cooling to room temperature, the bamboo charcoal is taken out, crushed and sieved to separate bamboo charcoal of 0~5 mm for use in the preparation of particleboard;

[0046] (2) Bamboo charcoal, silicate cement (PI42.5), and granulated blast furnace slag (main components include 35.7% CaO, 27.2% SiO2, 12.4% Al2O3, etc.) are mixed evenly in a mass ratio of 50:35:15 and stirred at 300 rpm for 5 minutes to obtain a mixed dry material; the bamboo charcoal needs to be pre-soaked in water for 12 hours before mixing and then drained to obtain saturated surface drying conditions; the silicate cement and mineral admixtures need to be dried in an oven at 105℃ to constant weight before mixing;

[0047] (3) Weigh the required water according to the mass ratio of water:(silicate cement + granulated blast furnace slag)=4:10, then weigh a portion of the mixed dry material, mix the water with the portion of mixed dry material, and stir at 500 rpm for 5 minutes to obtain fresh slurry;

[0048] (4) Weigh an appropriate amount of fresh slurry and divide it into two equal parts. First, pour half of the slurry into the steel mold, vibrate and flatten the surface, then put in basalt grid fiber with a mass ratio of 1% of the mixed dry material, and then pour the other half of the slurry into the mold to cover the basalt grid fiber, and vibrate and flatten the surface.

[0049] (5) Place the steel mold in the cold press and press it for 5 minutes under a pressure of 5MPa until the board has no springback. Then demold the board and put it into the CO2 carbonization curing box (temperature 20℃±2℃, relative humidity 75%±5%, pressure 1 MPa±0.1MPa, CO2 with a purity of 99%) for curing for 1 day. Then transfer it to the standard curing box (temperature 20℃±2℃, relative humidity 95%±5%, normal pressure) for curing for 6 days to obtain the finished biochar-based cement particleboard.

[0050] The basic properties, thermal conductivity, and noise reduction coefficient of biochar-based cement particleboard were tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusion Coefficient of Building Materials", and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The test results are shown in Table 2.

[0051] Example 3: A method for preparing biochar-based negative carbon functional cement particleboard, the specific steps of which are as follows:

[0052] (1) Collected waste bamboo materials (discarded disposable bamboo chopsticks, discarded bamboo frames, bamboo processing plant scraps, etc.) are dried to constant weight in an oven at 105℃, and then sent to a tube furnace at 500℃ for pyrolysis in a CO2 atmosphere at 200mL / min for 120 minutes to prepare bamboo charcoal. The heating rate of the pyrolysis furnace is 10℃ / min. After cooling to room temperature, the bamboo charcoal is taken out, crushed and sieved to separate bamboo charcoal of 0~5 mm for use in the preparation of particleboard;

[0053] (2) Bamboo charcoal, silicate cement (PI42.5), and granulated blast furnace slag (main components include 35.7% CaO, 27.2% SiO2, 12.4% Al2O3, etc.) are mixed evenly in a mass ratio of 60:28:12 and stirred at 300 rpm for 5 minutes to obtain a mixed dry material; the bamboo charcoal needs to be pre-soaked in water for 12 hours before mixing and then drained to obtain saturated surface drying conditions; the silicate cement and mineral admixtures need to be dried in an oven at 105℃ to constant weight before mixing;

[0054] (3) Weigh the required water according to the mass ratio of water:(silicate cement + granulated blast furnace slag)=4:10, then weigh a portion of the mixed dry material, mix the water with the portion of mixed dry material, and stir at 500 rpm for 5 minutes to obtain fresh slurry;

[0055] (4) Weigh an appropriate amount of fresh slurry and divide it into two equal parts. First, pour half of the slurry into the steel mold, vibrate and flatten the surface, then put in basalt grid fiber with a mass ratio of 1% of the mixed dry material, and then pour the other half of the slurry into the mold to cover the basalt grid fiber, and vibrate and flatten the surface.

[0056] (5) Place the steel mold in the cold press and press it for 5 minutes under a pressure of 5MPa until the board has no springback. Then demold the board and put it into a CO2 carbonization curing box (temperature 20℃±2℃, relative humidity 75%±5%, pressure 1MPa±0.1MPa, CO2 with a purity of 99%) for curing for 1 day. Then transfer it to a standard curing box (temperature 20℃±2℃, relative humidity 95%±5%, normal pressure) for curing for 6 days to obtain the finished biochar-based cement particleboard.

[0057] The basic properties, thermal conductivity, and noise reduction coefficient of biochar-based cement particleboard were tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusion Coefficient of Building Materials", and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The test results are shown in Table 2.

[0058] Comparative Example 1: A method for preparing a biochar-based negative carbon functional cement particleboard, the specific steps of which are as follows:

[0059] (1) Collected waste bamboo materials (discarded disposable bamboo chopsticks, discarded bamboo frames, scraps from bamboo processing plants, etc.) are dried to constant weight in an oven at 105℃, and then sent to a tube furnace at 500℃ for pyrolysis in a CO2 atmosphere at 200mL / min for 120 minutes to prepare bamboo charcoal. The heating rate of the pyrolysis furnace is 10℃ / min. After cooling to room temperature, the bamboo charcoal is taken out, crushed and sieved to separate bamboo charcoal of 0~5mm for use in the preparation of particleboard;

[0060] (2) Bamboo charcoal, silicate cement (PI42.5), and granulated blast furnace slag (main components include 35.7% CaO, 27.2% SiO2, 12.4% Al2O3, etc.) are mixed evenly in a mass ratio of 30:49:21 and stirred at 300 rpm for 5 minutes to obtain a mixed dry material; the bamboo charcoal needs to be pre-soaked in water for 12 hours before mixing and then drained to obtain saturated surface drying conditions; the silicate cement and mineral admixtures need to be dried in an oven at 105℃ to constant weight before mixing;

[0061] (3) Weigh the required water according to the mass ratio of water:(silicate cement + granulated blast furnace slag)=4:10, then weigh a portion of the mixed dry material, mix the water with the portion of mixed dry material, and stir at 500 rpm for 5 minutes to obtain fresh slurry;

[0062] (4) Weigh an appropriate amount of fresh slurry and divide it into two equal parts. First, pour half of the slurry into the steel mold, vibrate and flatten the surface, then put in basalt grid fiber with a mass ratio of 1% of the mixed dry material, and then pour the other half of the slurry into the mold to cover the basalt grid fiber, and vibrate and flatten the surface.

[0063] (5) Place the steel mold in the cold press and press it for 5 minutes under a pressure of 5MPa until the board has no springback. Then demold the board and put it into a CO2 carbonization curing box (temperature 20℃±2℃, relative humidity 75%±5%, pressure 1MPa±0.1MPa, CO2 with a purity of 99%) for curing for 1 day. Then transfer it to a standard curing box (temperature 20℃±2℃, relative humidity 95%±5%, normal pressure) for curing for 6 days to obtain the finished biochar-based cement particleboard.

[0064] The performance of biochar-based cement particleboard was tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusivity of Building Materials" and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The test results are shown in Table 2.

[0065] Comparative Example 2: A method for preparing a biochar-based negative carbon functional cement particleboard, the specific steps of which are as follows:

[0066] (1) Collected waste bamboo materials (discarded disposable bamboo chopsticks, discarded bamboo frames, scraps from bamboo processing plants, etc.) are dried to constant weight in an oven at 105℃, and then sent to a tube furnace at 500℃ for pyrolysis in a CO2 atmosphere at 200mL / min for 120 minutes to prepare bamboo charcoal. The heating rate of the pyrolysis furnace is 10℃ / min. After cooling to room temperature, the bamboo charcoal is taken out, crushed and sieved to separate bamboo charcoal of 0~5mm for use in the preparation of particleboard;

[0067] (2) Bamboo charcoal, silicate cement (PI42.5), and granulated blast furnace slag (main components include 35.7% CaO, 27.2% SiO2, 12.4% Al2O3, etc.) are mixed evenly in a mass ratio of 70:21:9 and stirred at 300 rpm for 5 minutes to obtain a mixed dry material; the bamboo charcoal needs to be pre-soaked in water for 12 hours before mixing and then drained to obtain saturated surface drying conditions; the silicate cement and mineral admixtures need to be dried in an oven at 105℃ to constant weight before mixing;

[0068] (3) Weigh the required water according to the mass ratio of water:(silicate cement + granulated blast furnace slag)=4:10, then weigh a portion of the mixed dry material, mix the water with the portion of mixed dry material, and stir at 500 rpm for 5 minutes to obtain fresh slurry;

[0069] (4) Weigh an appropriate amount of fresh slurry and divide it into two equal parts. First, pour half of the slurry into the steel mold, vibrate and flatten the surface, then put in basalt grid fiber with a mass ratio of 1% of the mixed dry material, and then pour the other half of the slurry into the mold to cover the basalt grid fiber, and vibrate and flatten the surface.

[0070] (5) Place the steel mold in the cold press and press it for 5 minutes under a pressure of 5MPa until the board has no springback. Then demold the board and put it into a CO2 carbonization curing box (temperature 20℃±2℃, relative humidity 75%±5%, pressure 1MPa±0.1MPa, CO2 with a purity of 99%) for curing for 1 day. Then transfer it to a standard curing box (temperature 20℃±2℃, relative humidity 95%±5%, normal pressure) for curing for 6 days to obtain the finished biochar-based cement particleboard.

[0071] The performance of biochar-based cement particleboard was tested according to GB / T24312-2022 "Cement Particleboard", GB / T32064-2015 "Test Method for Transient Plane Heat Source of Thermal Conductivity and Thermal Diffusivity of Building Materials" and GB / T16731-2023 "Classification of Sound Absorption Performance of Building Sound Absorption Products". The test results are shown in Table 2.

[0072] Table 1. Raw material ratios (by mass) for specific embodiments and comparative examples.

[0073]

[0074] Note 1: The water addition ratio is 0.4 times the sum of the mass of silicate cement and granulated blast furnace slag;

[0075] Note 2: The proportion of basalt grid fiber is 0.01 of the sum of the mass of biochar, silicate cement and granulated blast furnace slag.

[0076] Table 2 Performance test results of specific embodiments and comparative examples

[0077]

[0078] A comparison of Examples 1, 2, and 3 with Comparative Examples 1 and 2 reveals that as the biochar content gradually increases from 30% to 70%, the density of biochar-based cement particleboard gradually decreases, the moisture content ranges from 6% to 16%, and the 24-hour thickness expansion rate after water absorption is less than 2%, meeting the requirements of standard GB / T24312-2022 "Cement Particleboard". Simultaneously, its thermal conductivity gradually decreases, while its noise reduction coefficient (NRC) gradually increases, indicating improved thermal insulation and sound insulation performance. Furthermore, since biochar is a good negative carbon material, as the biochar content increases, the carbon emissions of biochar-based cement particleboard gradually decrease and reach negative values, contributing to carbon reduction in the construction industry. However, with increasing biochar content, the static bending strength of biochar-based cement particleboard gradually decreases. The standard GB / T24312-2022 "Cement Particleboard" specifies that the static bending strength of cement particleboard should be ≥9MPa. However, in Comparative Example 2, when the biochar content is 70%, the static bending strength is less than 9MPa, failing to meet the standard requirements. Furthermore, slight through-cracks appeared on the surface during the impact test. Therefore, the biochar content in biochar-based cement particleboard should not be too high (exceeding 60%), otherwise the product's mechanical properties will not meet the standard requirements. Conversely, the biochar content should not be too low either; as in Comparative Example 1, the product density is too high, resulting in poor thermal insulation and noise reduction performance, increased cost and carbon emissions, and an inability to meet market demands in practical applications.

[0079] In general, increasing the proportion of biochar incorporation leads to a decrease in the mechanical properties of biochar-based cement particleboard, but the resulting product is lighter and carbon-negative, while also exhibiting enhanced thermal insulation and sound absorption properties. However, excessively high biochar incorporation can cause the mechanical properties of the biochar-based cement particleboard to fail to meet standard requirements. Therefore, the biochar incorporation ratio should be rationally selected based on the needs of the actual application. The preferred biochar incorporation ratio recommended by this invention is 60%.

[0080] The above description is merely a preferred embodiment of the present invention. Although the preferred embodiments have been disclosed above, they are not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A method for preparing biochar-based negative carbon functional cement particleboard, characterized in that, include: Porous biochar is obtained by pyrolysis, crushing, and sieving of biomass at 400-600 °C. The pyrolysis conditions are as follows: in a CO2 atmosphere of 200 ± 10 mL / min, the temperature is increased to 400-600 °C at a rate of 10 ± 1 °C / min, and pyrolysis is carried out for 90-150 minutes. The porous biochar, silicate cement, and mineral admixtures are uniformly mixed and stirred in a mass ratio of (40~60):(28~42):(12~18) to obtain a mixed dry material; Add water to the mixed dry materials and stir evenly to obtain a slurry. The mass ratio of the added water to the mixture of silicate cement and mineral admixtures is 0.38 to 0.

42. First, the slurry is divided into two equal parts. Half of the slurry is placed into the mold and basalt grid fiber is added. Then, the other half of the slurry is added to cover the basalt grid fiber. The surface is vibrated and flattened. After pressing, the mold is demolded to obtain the board blank. The basalt grid fiber is in the form of a mesh. The board blank is first subjected to CO2 carbonization curing, and then subjected to standard curing to obtain biochar-based negative carbon functional cement particleboard. The basalt grid fiber is added to the slurry at a mass ratio of 1% to 3% of the mixed dry material; The mineral admixture is granulated blast furnace slag or fly ash. Before mixing the porous biochar, soak it in water for 12 to 15 hours and then drain it. Before mixing, dry the silicate cement and mineral admixtures in an oven at 105 ± 1 °C until they reach constant weight.

2. The method for preparing biochar-based negative carbon functional cement particleboard according to claim 1, characterized in that, The biomass refers to bamboo, wood, and straw.

3. The method for preparing biochar-based negative carbon functional cement particleboard according to claim 1, characterized in that, The size of the sieved porous biochar is 0 ~ 5 mm, excluding the endpoint 0.

4. The method for preparing biochar-based negative carbon functional cement particleboard according to claim 1, characterized in that, The parameters for CO2 carbonization curing are: temperature 20 °C ± 2 °C, relative humidity 75% ± 5%, pressure 1 MPa ± 0.1 MPa, and CO2 with a purity of 99% is introduced. The parameters for standard curing are: temperature 20 °C ± 2 °C, relative humidity 95% ± 5%, atmospheric pressure, and standard curing time 6 days.

5. A biochar-based negative carbon functional cement particleboard, characterized in that, The biochar-based negative carbon functional cement particleboard is prepared by the preparation method of biochar-based negative carbon functional cement particleboard according to any one of claims 1-4.

6. The biochar-based negative carbon functional cement particleboard according to claim 5, characterized in that, The biochar-based negative carbon functional cement particleboard has a moisture content of 8% to 12%, a 24-hour water absorption thickness expansion rate of ≤ 2%, a static bending strength of 9 to 12.5 MPa, exhibits no through-cracks in the impact resistance test, and has a density of 900 to 1250 kg / m³. 3 It has a thermal conductivity of 0.25 ~ 0.45 W / (m·K), a noise reduction factor (NRC) ≥ 0.4, and a negative carbon footprint throughout its entire life cycle.

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