CN114772956A - High-carbon-absorption early-strength cementing material based on recycled concrete powder and biochar and application thereof - Google Patents

High-carbon-absorption early-strength cementing material based on recycled concrete powder and biochar and application thereof Download PDF

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CN114772956A
CN114772956A CN202210248398.5A CN202210248398A CN114772956A CN 114772956 A CN114772956 A CN 114772956A CN 202210248398 A CN202210248398 A CN 202210248398A CN 114772956 A CN114772956 A CN 114772956A
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biochar
carbon
recycled concrete
concrete powder
absorption
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CN114772956B (en
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张同生
王龙龙
郭奕群
韦江雄
余其俊
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South China University of Technology SCUT
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C04B7/246—Cements from oil shales, residues or waste other than slag from waste building materials, e.g. waste asbestos-cement products, demolition waste
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/02—Selection of the hardening environment
    • C04B40/0231—Carbon dioxide hardening
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
    • C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]

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  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Inorganic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention provides a high-carbon-absorption early-strength cementing material based on recycled concrete powder and biochar and application thereof, and relates to the technical field of building materials and the field of environmental protection. The invention takes recycled concrete powder and siliceous adjusting component as main raw materials, and generates Gamma-C by directional induction through designing a firing system2S, adding porous charcoal particles to improve CO2Diffusion capacity and penetration depth, production of CO2The carbon-absorbing cementing material with the absorption quality of 15-20% can cement aggregate in the carbon absorption process to form a hardened body with the strength of more than 50 MPa. The carbon-absorbing cementing material prepared from the waste and the biochar not only can improve the CO content of the cement-based material2The absorption capacity can be improved by utilizing the carbonate reaction, the early strength of the hardened body is improved, and the method has remarkable energy conservation and emission reduction,Environmental protection and the like.

Description

High-carbon-absorption early-strength cementing material based on recycled concrete powder and biochar and application thereof
Technical Field
The invention relates to the technical field of building materials and the field of environmental protection, in particular to a high carbon absorption early strength cementing material based on regenerated concrete powder and biochar and application thereof.
Background
The carbon emission of the building industry accounts for about 40% of the carbon emission generated by human activities, and faces huge carbon emission reduction pressure. CO absorption by cement-based materials2It can reduce carbon emission in building material industry and realize CO2Is an important approach to long-term sequestration. The calcium silicate mineral in the portland cement has high carbonation activity and can absorb a large amount of CO under the carbonation curing condition2However, the preparation of clinker needs to consume a large amount of high-grade limestone and coal resources, and the carbon emission reduction potential of directly applying portland cement to absorb carbon is small. It was found that in addition to C3S、β-C2Gamma-C other than hydraulic calcium silicates such as S2S、 CS、C3S2The non-hydraulic calcium silicate minerals also have excellent carbonation potential, wherein gamma-C2S is concerned because of low calcium content and high carbonation rate, and is expected to be developed into a carbon-absorbing gel material.
A large amount of recycled concrete powder is generated in the process of preparing recycled aggregate by using waste concrete, and the recycled aggregate has high water absorption rate and low activity and is difficult to be directly utilized as an auxiliary cementing material. The recycled concrete powder has high CaO content and is prepared from C-S-H, Ca (OH)2、CaCO3The calcium carbonate exists in the forms of the calcium carbonate, the decomposition temperature is low, and the calcium carbonate can be used as a calcium raw material for preparing the carbon-absorbing gelling material. SiO in recycled concrete powder2The content is low, the crystal exists in a quartz form, the crystallization degree and the activation energy are high, the solid-phase reaction with CaO is difficult, and the gamma-C is severely restricted2And (4) sintering of S. Therefore, how to fully utilize the high calcium characteristic of the recycled concrete powder to promote CaO and SiO2The occurrence of a solid phase reaction with gamma-C2The formation of S is the key for preparing the carbon-absorbing gelling material by efficiently utilizing wastes.
Existing CO2In curing cement-based materials, the initial porosity of the cement product is typically controlled using the forming pressure. Increased molding pressure, reduced initial porosity of the article, CO2The permeation is hindered, the carbonation degree of the material is limited, and the strength is slowly developed; the molding pressure is reduced, the initial porosity of the product is higher although CO2The penetration depth is increased, but the initial porosity of the product is higher and the strength is lower. Due to the fact thatHow to increase CO in compact cement products2The penetration depth is another key problem for improving the carbon absorption capacity and breaking through the carbonation performance of the cement product.
Disclosure of Invention
Aiming at the problems, the invention regulates and controls the proportion of the recycled concrete powder and the siliceous regulating component based on the cement clinker firing theory, and adopts a gradient heating and cooling system to directionally induce gamma-C2And (5) generating S, and preparing the carbon-absorbing gel material. In addition, according to CO2The seepage principle in multi-element solid utilizes the multi-scale communicated pore characteristics of the biochar to design the matching of the biochar and the carbon-absorbing gelling material in the aspects of particle size, mixing amount, pore structure and the like. By controlling factors such as the volume mixing amount threshold value of the biochar, the molding pressure and the like, the high-efficiency communication between micro-scale pores (particle stacking communication pores) and nano-scale pores (biochar communication pores) is realized, and a communication pore network is formed in a compact cement product and is CO2The migration and the permeation of the cement provide a quick channel, so that the carbon absorption capacity and the early mechanical property of the cement product are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high carbon absorption early strength cementing material based on recycled concrete powder and biochar, wherein the threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01P+0.13d-0.0014εr2Calculation of where VthreIs the threshold value of the volume doping amount of the biochar,%; p is the pressure of the high carbon absorption early strength cementing material during molding, and is MPa; d is the average particle size of the biochar, mu m; epsilon is the porosity of the biochar,%; r is the average pore diameter of the biochar, and is mum; 1.1 to 1.5 times of VthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Further, the biochar is one or more than two of wood charcoal, rice hull charcoal and straw charcoal, the average particle size of the biochar is 50-200 mu m, the porosity of the biochar is 50-90%, and the average pore size of the biochar is 0.5-10 mu m.
Further, the carbon-absorbing gelling material prepared from the recycled concrete powder is as follows: according to the specific value KH is 0.67-0.70, SM is 2.5-4.0, and IM is 15-3.0, weighing 60-90 wt% of recycled concrete powder and 10-40 wt% of siliceous adjusting component, mixing and grinding to obtain a mixture with a specific surface area of 250-350 m2Per kg, grinding the mixture after gradient temperature rising calcining and cooling to the specific surface area of 300-450 m2/kg, obtaining gamma-C2The carbon-absorbing gel material contains 55-75 wt% of S.
Further, the CaO content of the recycled concrete powder is 40-80 wt%, and SiO content is210-20 wt% of Al2O3The content is 0 to 10 wt%.
Further, the siliceous adjusting component is one or more than two of clay brick powder, sludge and glass slag, the CaO content of the siliceous adjusting component is 0-20 wt%, and SiO is260-80 wt% of Al2O3The content is 0 to 20 wt%.
Preferably, the clay brick powder contains 0-10 wt% of CaO and SiO260-80 wt% of Al2O3The content is 0-15 wt%; drying the sludge, controlling the water content to be less than or equal to 2%, the CaO content to be 0-5 wt%, and SiO260-75 wt% of Al2O3The content is 10-20 wt%; the content of CaO in the glass slag is 0-15 wt%, and SiO in the glass slag260-75 wt% of Al2O3The content is 0 to 15 wt%.
Further, the gradient temperature-rising calcining and cooling system comprises the following steps: heating to 850-900 deg.C at a rate of 5-30 deg.C/min, and maintaining for 0.5-1 h to decompose carbonate and obtain crystalline SiO2Activating; then raising the temperature to 1250-1400 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 1-3 h to ensure that CaO and SiO are mixed2By solid-phase reaction to form C2S; cooling to 520-530 ℃ at the speed of 100-300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and using beta-C2S direction gamma-C2The crystal form of S is changed, so that the clinker is self-pulverized, and the carbonation activity of the carbon-absorbing cementing material is improved.
The application of the high carbon absorption early strength cementing material based on the recycled concrete powder and the biochar is that 70-90 wt% of the high carbon absorption early strength cementing material and 10-30 wt% of water are uniformly mixed, then the high carbon absorption early strength cementing material and the water are uniformly mixed with aggregate with the volume 2-5 times of that of the aggregate, and then the aggregate is mixed with the mixturePressing and molding under the pressure of 2-5 MPa, standing for 24 hours in a reaction kettle with the relative humidity of 50-70%, and finally carrying out CO compression molding at the temperature of 20 +/-2 DEG C2After curing for 24 hours in an environment with the concentration of 20-90% and the relative humidity of 50-70%, the compressive strength can reach more than 50MPa, and CO is2The absorption mass can reach more than 15% of the mass of the carbon-absorbing gel material.
Compared with the prior art, the invention has the beneficial effects that:
1) based on a clinker sintering theory, the carbon-absorbing cementing material is prepared by using wastes such as recycled concrete powder and clay brick powder as raw materials and adopting a gradient heating and cooling system, so that the high-efficiency utilization of the wastes is promoted, the consumption of natural resources and primary energy is reduced, and the carbon emission reduction of the building material industry is promoted.
2) According to the seepage principle, based on the multi-scale communicated pore characteristics of the biochar, the pore communication in the high-density cement product is realized by controlling factors such as the volume mixing amount threshold value and the forming pressure of the biochar, and is CO2Provides a migration and permeation channel, and effectively improves the carbon absorption capacity and early strength of the cement product.
Detailed Description
The present invention will be described in further detail with reference to examples, but the method of carrying out the present invention is not limited thereto.
The raw materials of the carbon-absorbing cementing materials prepared in the comparative examples and the examples of the invention are recycled concrete powder, clay brick powder, sludge and glass slag, and the chemical compositions of the materials are shown in the following table 1.
TABLE 1 raw material chemical composition (wt%) for carbon-absorbing gelling material
Figure BDA0003545825380000051
Mixing and grinding the raw materials according to a certain proportion until the specific surface area is 250-350 m2Per kg, heating to 850-900 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 0.5-1 h; then heating to 1250-1400 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 1-3 h; cooling to 520-530 ℃ at the speed of 100-300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and powderingGrinding to a specific surface area of 300-450 m2Kg, to obtain gamma-C2The carbon-absorbing gel material contains 55-75 wt% of S. And mixing a certain amount of the biochar with the carbon-absorbing cementing material prepared from the regenerated concrete powder to form the high-carbon-absorbing early-strength cementing material according to the calculated threshold value of the volume mixing amount of the biochar.
Uniformly mixing 70-90 wt% of high-carbon-absorption early-strength cementing material and 10-30 wt% of water, then uniformly mixing with aggregate with the volume 2-5 times that of the high-carbon-absorption early-strength cementing material, then performing compression molding at the pressure of 2-5 MPa, standing for 24 hours in a reaction kettle with the relative humidity of 50-70%, and finally performing CO (carbon monoxide) reaction at the temperature of 20 +/-2℃ for 24 hours2Curing for 24 hours in an environment with the concentration of 20-90% and the relative humidity of 50-70%.
Comparative example and example of the present invention CO2And testing the compressive strength of the mortar cured for 24 hours, wherein the compressive strength is tested according to GB/T17671-1999 cement mortar strength test method (ISO method). By CO2The absorption mass represents the carbon absorption properties of the compacted cementitious article and is calculated as follows:
Figure BDA0003545825380000061
wherein: m is0Is CO2Dry weight of mortar before curing, m1Is CO2Dry weight, m, of cured mortar2Is the quality of the carbon-absorbing gelling material.
Comparative example 1
Weighing 87.8 wt% of recycled concrete powder and 12.2 wt% of sludge, mixing and grinding to obtain a mixture with a specific surface area of 250-350 m2/kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1250 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2Kg, to obtain gamma-C2The S content of the carbon-absorbing gel material is 56.7 wt%.
Uniformly mixing 87.1 wt% of carbon-absorbing gelling material and 12.9 wt% of water, then uniformly mixing with machine-made sand with the volume 4.2 times that of the mixture, then performing compression molding at the pressure of 2.0MPa, and performing reaction in a reaction kettle with the relative humidity of 60%Standing for 24 hr, and adding CO at 20 + -2 deg.C2Curing for 24 hours in an environment with the concentration of 50% and the relative humidity of 60%. Mortar CO thereof2The compressive strength is 28.9MPa after 24h of curing, and CO2The absorption mass is 9.8 percent of the mass of the carbon-absorbing gel material.
Comparative example 2
Weighing 88.1 wt% of recycled concrete powder and 11.9 wt% of clay brick powder, mixing and grinding the materials to a specific surface area of 250-350 m2/kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1300 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2Kg, to obtain gamma-C2The carbon-absorbing gelling material with the S content of 65.2wt percent.
Mixing 86.8 wt% of carbon-absorbing gelling material and 13.2 wt% of water uniformly, then mixing the mixture with machine-made sand with the volume being 3.8 times that of the mixture, then pressing and forming the mixture in a reaction kettle with the relative humidity being 50% under the pressure of 5.0MPa, standing the mixture for 24 hours, and finally pressing and forming the mixture at the temperature of 20 +/-2 ℃ and CO for 24 hours2Curing for 24 hours in an environment with the concentration of 20% and the relative humidity of 50%. Mortar CO thereof2The compressive strength is 46.2MPa after 24h of curing, and CO2The absorption mass is 4.5 percent of the mass of the carbon-absorbing gel material.
Comparative example 3
Weighing 86.4 wt% of recycled concrete powder and 13.6 wt% of glass slag, mixing and grinding to obtain a specific surface area of 250-350 m2Heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5 h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2/kg, obtaining gamma-C2The S content of the carbon-absorbing gel material is 71.2 wt%. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47236.5%, the biochar is straw carbon with average particle size of 172.42 μm, porosity of 85.7%, average pore diameter of 3.47 μm, and the volume of the biochar is 0.5 times VthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Mixing 83.2 wt% of high carbon absorption early strength cementing material and 16.8 wt% of water uniformly, then mixing with 3.1 times volume of machine-made sand uniformly, then pressing and forming under the pressure of 4.0MPa, standing in a reaction kettle with the relative humidity of 70% for 24h, and finally keeping the reaction kettle at the temperature of 20 +/-2 ℃ and CO for 24h2Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof2The compressive strength is 34.5MPa after 24h of curing, and CO2The absorption mass is 8.4 percent of the mass of the carbon-absorbing gel material.
Comparative example 4
Weighing 86.4 wt% of recycled concrete powder and 13.6 wt% of glass slag, mixing and grinding the materials to a specific surface area of 250-350 m2/kg, heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5 h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2 h; cooling to 525 deg.C at 300 deg.C/min, holding for 30min, cooling to room temperature, and grinding to specific surface area of 300-450 m2/kg, obtaining gamma-C2The carbon-absorbing gel material with the S content of 71.2wt percent. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47236.5 percent, the biochar is straw carbon, the average particle size is 172.42 mu m, the porosity is 85.7 percent, the average pore diameter is 3.47 mu m, and the volume is 3.0 times VthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Mixing 83.2 wt% of high carbon absorption early strength cementing material and 16.8 wt% of water uniformly, then mixing with 3.1 times volume of machine-made sand uniformly, pressing and forming under the pressure of 4.0MPa, standing in a reaction kettle with the relative humidity of 70% for 24h, and finally keeping the temperature at 20 +/-2 ℃ and CO for 24h2Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof2The compressive strength is 19.4MPa after 24h of curing, and CO2The absorption mass is 16.9 percent of the mass of the carbon-absorbing gel material.
Example 1
Weighing 87.8 wt% of recycled concrete powder and 12.2 wt% of sludge, mixing and grinding the materials to a specific surface area of 250-350 m2Heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1250 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; to be provided withCooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2/kg, obtaining gamma-C2The S content of the carbon-absorbing gel material is 56.7 wt%. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×2.0+0.13×172.42-0.0014×85.7× 3.47232.5 percent, the biochar is straw carbon with the average particle size of 172.42 mu m, the porosity of 85.7 percent and the average pore diameter of 3.47 mu m, and the volume ratio of the biochar is 1.1 times VthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Uniformly mixing 87.1 wt% of high carbon absorption early strength cementing material and 12.9 wt% of water, then uniformly mixing with 4.2 times of volume of machine-made sand, then performing compression molding at 2.0MPa, standing for 24h in a reaction kettle with relative humidity of 60%, and finally performing CO condensation at 20 +/-2 ℃ for 24h2Curing for 24 hours in an environment with the concentration of 50% and the relative humidity of 60%. Mortar CO thereof2The compressive strength is 52.5MPa after 24h of curing, and CO2The absorption mass is 15.2 percent of the mass of the carbon-absorbing gel material.
Example 2
Weighing 88.1 wt% of recycled concrete powder and 11.9 wt% of clay brick powder, mixing and grinding the materials to a specific surface area of 250-350 m2/kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1300 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2/kg, obtaining gamma-C2The S content of the carbon-absorbing gel material is 65.2 wt%. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×5.0+0.13×172.42-0.0014×85.7 ×3.47238.5 percent, the biochar is straw carbon with the average particle size of 172.42 mu m, the porosity of 85.7 percent and the average pore diameter of 3.47 mu m, and the volume ratio of the biochar is 1.1 times VthreThe biochar is mixed with a carbon-absorbing gelling material prepared from recycled concrete powder to form the high-carbon-absorbing early-strength gelling material.
Mixing 86.8 wt% of high carbon absorption early strength cementing material and 13.2 wt% of water uniformly, then mixing the mixture with 3.8 times volume of machine-made sand uniformly, then pressing and forming the mixture under the pressure of 5.0MPa, and finally, adding the mixture into a moldStanding in a reaction kettle with relative humidity of 50% for 24h, and finally keeping CO at 20 +/-2 deg.C2Curing for 24 hours in an environment with the concentration of 20% and the relative humidity of 50%. Mortar CO thereof2The compressive strength is 61.2MPa after 24h of curing, and CO2The absorption mass is 15.7 percent of the mass of the carbon-absorbing gel material.
Example 3
Weighing 86.4 wt% of recycled concrete powder and 13.6 wt% of glass slag, mixing and grinding to obtain a specific surface area of 250-350 m2/kg, heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5 h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2/kg, obtaining gamma-C2The S content of the carbon-absorbing gel material is 71.2 wt%. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47236.5 percent, the biochar is straw carbon with the average particle size of 172.42 mu m, the porosity of 85.7 percent and the average pore diameter of 3.47 mu m, and the volume is 1.3 times of the volumethreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Mixing 83.2 wt% of high carbon absorption early strength cementing material and 16.8 wt% of water uniformly, then mixing with 3.1 times volume of machine-made sand uniformly, then pressing and forming under the pressure of 4.0MPa, standing in a reaction kettle with the relative humidity of 70% for 24h, and finally keeping the reaction kettle at the temperature of 20 +/-2 ℃ and CO for 24h2Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof2The compressive strength is 65.3MPa after 24h of curing, and CO is2The absorption mass is 16.1 percent of the mass of the carbon-absorbing gel material.
Example 4
Weighing 87.3 wt% of recycled concrete powder, 4.6 wt% of glass slag and 8.1 wt% of clay brick powder, mixing and grinding the materials until the specific surface area is 250-350 m2Heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1400 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; cooling to 525 deg.C at 300 deg.C/min, holding for 30min, cooling to room temperature, and grinding to specific surface area of 300-450 m2Kg, to obtain gamma-C2The S content is 69.3 percent. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×3.0+0.13× 132.77-0.0014×75.8×1.23230.6 percent, the biochar is wood charcoal with the average grain diameter of 132.77 mu m, the porosity of 75.8 percent and the average pore diameter of 1.23 mu m, and the volume of the biochar is 1.3 times of the volume of the biocharthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
Mixing 86.9 wt% of high carbon absorption early strength cementing material and 13.1 wt% of water uniformly, then mixing with 3.7 times volume of machine-made sand uniformly, then pressing and forming under the pressure of 3.0MPa, standing for 24h in a reaction kettle with the relative humidity of 60%, and finally keeping the reaction kettle at the temperature of 20 +/-2 ℃ and CO2Curing for 24 hours in an environment with the concentration of 70% and the relative humidity of 60%. Mortar CO thereof2The compressive strength is 66.7MPa after 24h of curing, and CO2The absorption mass is 17.2 percent of the mass of the carbon-absorbing gel material.
Example 5
Weighing 88.0 wt% of recycled concrete powder, 6.2 wt% of clay brick powder and 5.8 wt% of sludge, mixing and grinding to a specific surface area of 250-350 m2Heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1 h; then heating to 1400 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3 h; cooling to 525 ℃ at the speed of 300 ℃/min, keeping the temperature for 30min, cooling to room temperature along with the furnace, and then grinding to the specific surface area of 300-450 m2Kg, to obtain gamma-C2The S content is 67.8 percent. The threshold value of the volume mixing amount of the biochar is Vthre＝7.47+2.01×3.0+0.13× 73.54-0.0014×72.6×2.39222.5 percent of the total weight of the raw materials, namely the biochar is rice husk carbon with the average particle size of 73.54 mu m, the porosity of 72.6 percent and the average pore diameter of 2.39 mu m, and the volume of the biochar is 1.5 times that of the biocharthreThe biochar is mixed with a carbon-absorbing gelling material prepared from recycled concrete powder to form the high-carbon-absorbing early-strength gelling material.
Mixing 78.6 wt% of high carbon absorption early strength cementing material and 21.4 wt% of water uniformly, then mixing with 2.4 times volume of machine-made sand uniformly, then pressing and forming under the pressure of 3.0MPa, standing for 24h in a reaction kettle with the relative humidity of 60%, and finally keeping the reaction kettle at the temperature of 20 +/-2 ℃ and CO2Curing in an environment with a concentration of 90% and a relative humidity of 60%And (5) 24 h. Mortar CO thereof2The compressive strength is 63.7MPa after 24h of curing, and CO2The absorption mass is 16.8 percent of the mass of the carbon-absorbing gel material.
Comparative example of the invention, example CO2The physical properties of the cured high carbon absorption early strength cementitious material are shown in table 2 below.
TABLE 2 CO of comparative examples and examples2Physical properties of cured high carbon absorption early strength cementitious material
Figure BDA0003545825380000121
Compared with the comparative example 1, the example 1 is formed by mixing the biochar and CO on the basis of the carbon-absorbing gel material2After 24 hours of maintenance, the strength of the mortar is improved from 28.9MPa to 52.5MPa, and CO is added2The absorption quality is improved by 5.4%; when the forming pressure is 5.0MPa, compared with the comparative example 2, the example 2 is characterized in that the biochar and CO are mixed in the carbon-absorbing gel material2After 24 hours of maintenance, the strength of the mortar is improved from 46.2MPa to 61.2MPa, and CO is added2The absorption quality is improved by 11.2%; the mixing amount of the active carbon and the biochar is 0.5 times VthrCompared with comparative example 3, the biochar mixing amount of example 3 is 1.3 times Vthre， CO2After 24 hours of maintenance, the strength of the mortar is improved from 34.5MPa to 65.3MPa, and CO is added2The absorption quality is improved from 8.4 percent to 16.1 percent; the mixing amount of the active carbon and the biochar is 3.0 times VthreComparative example 4 compared to CO of example 32The absorption mass was reduced from 16.9% to 16.1%, but CO2The strength of the mortar is improved from 19.4MPa to 65.3MPa after 24 hours of maintenance. The above examples all show that the volume doping amount of the biochar is 1.1-1.5 times V by controlling the matching of the biochar and the carbon-absorbing gelling material in the aspects of particle size, pore structure and the likethreWithin the range, the communication between the particle stacking pores and the biochar pores can be realized, a communicated pore network is formed in a compact cement product, and the CO is effectively promoted2The migration and the penetration enable the high carbon absorption early strength cementing material prepared by the embodiment of the invention to have excellent carbon absorption performance and mechanical property. Example 4 the biochar used was wood charcoal, CO2The mortar strength after 24h of curing is 66.7MPa, and CO2The absorption mass is17.2 percent; example 5 the biochar used was rice husk charcoal, CO2The mortar strength after 24h of curing is 63.7MPa, and CO2The absorption mass is 16.8%, which shows that the same rule and effect are realized by adopting other types of biochar.
The above is merely a preferred embodiment of the present invention, and is not intended to limit the present invention, and any modification and improvement made within the principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The high-carbon-absorption early-strength cementing material based on the recycled concrete powder and the biochar is characterized in that the threshold value of the volume mixing amount of the biochar is Vthr＝7.47+2.01P+0.13d-0.0014εr2Calculation of where VthreIs the threshold value of the volume mixing amount of the biochar,%; p is the pressure of the high carbon absorption early strength cementing material during molding, and is MPa; d is the average particle size of the biochar, mu m; epsilon is the porosity of the biochar,%; r is the average pore diameter of the biochar, and is mum; 1.1 to 1.5 times of VthreThe biochar and the carbon-absorbing cementing material prepared from the recycled concrete powder are mixed to form the high-carbon-absorbing early-strength cementing material.
2. The high carbon absorption and early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 1, wherein the biochar is one or more of straw carbon, wood carbon and rice husk carbon, and has an average particle size of 50-200 μm, a porosity of 50-90% and an average pore size of 0.5-10 μm.
3. The high carbon absorption early strength cementitious material based on the recycled concrete powder and the biochar as claimed in claim 1, characterized in that the carbon absorption cementitious material prepared from the recycled concrete powder is: weighing 60-90 wt% of recycled concrete powder and 10-40 wt% of siliceous adjusting component, mixing and grinding until the specific surface area is 250-350 m2Per kg, grinding the mixture after gradient temperature rise calcination and cooling to the specific surface area of 300-450 m2Kg, to obtain gamma-C2The carbon-absorbing gel material contains 55-75 wt% of S.
4. The high carbon absorption early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 3, wherein the CaO content of the recycled concrete powder is 40-80 wt%, SiO210-40 wt% of Al2O3The content is 0 to 20 wt%.
5. The high carbon absorption and early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 3, wherein the siliceous adjusting component is one or more of clay brick powder, sludge and glass slag, the CaO content of the siliceous adjusting component is 0-20 wt%, and SiO is SiO260-80 wt% of Al2O3The content is 0 to 20 wt%.
6. The high carbon absorption early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 3, wherein the gradient temperature rising calcination and cooling system is as follows: heating to 850-900 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 0.5-1 h; then heating to 1250-1400 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 1-3 h; cooling to 520-530 ℃ at the speed of 100-300 ℃/min, keeping the temperature for 30min, and then cooling to room temperature along with the furnace.
7. The application of the high carbon absorption early strength cementing material based on the recycled concrete powder and the biochar as claimed in any one of claims 1 to 6 is characterized by comprising the following steps: uniformly mixing the high-carbon absorption early-strength cementing material with water, then uniformly mixing the high-carbon absorption early-strength cementing material with aggregate with the volume of 2-5 times, then performing compression molding, standing in a reaction kettle with the relative humidity of 50-70%, and finally performing CO (carbon monoxide) treatment at the temperature of 20 +/-2 DEG C2After curing in an environment with the concentration of 20-90% and the relative humidity of 50-70%, the compressive strength can reach more than 50MPa, and CO2The absorption quality can reach more than 15 percent of the mass of the carbon-absorbing gelling material.
8. The application of the high carbon absorption early strength cementing material based on the recycled concrete powder and the biochar as claimed in claim 7, wherein the pressure of the compression molding is 2-5 MPa.
9. The application of the high carbon absorption early strength cementitious material based on the recycled concrete powder and the biochar as claimed in claim 7, is characterized in that the addition amount of the high carbon absorption early strength cementitious material and water is as follows: 70-90 wt% of high carbon absorption early strength cementing material and 10-30 wt% of water.
10. The application of the high carbon absorption and early strength cementing material based on the recycled concrete powder and the biochar as claimed in claim 7, characterized in that the standing time is 24 hours; the curing time is 24 hours.
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CN115432969A (en) * 2022-08-30 2022-12-06 中建一局集团建设发展有限公司 Biochar concrete with carbon fixing capacity for 3D printing and preparation method thereof
GB2623581A (en) * 2022-10-21 2024-04-24 Adaptavate Ltd Construction product

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GB2623581A (en) * 2022-10-21 2024-04-24 Adaptavate Ltd Construction product

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