CN114772956B - 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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CN114772956B
CN114772956B CN202210248398.5A CN202210248398A CN114772956B CN 114772956 B CN114772956 B CN 114772956B CN 202210248398 A CN202210248398 A CN 202210248398A CN 114772956 B CN114772956 B CN 114772956B
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biochar
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recycled concrete
early strength
concrete powder
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CN114772956A (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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  • Ceramic Engineering (AREA)
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  • Inorganic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention providesA high carbon absorption early strength cementing material based on recycled concrete powder and biochar and application thereof relate to the field of building material technology and 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 system 2 S, adding porous biochar particles to improve CO 2 Diffusion capacity and penetration depth, production of CO 2 The carbon-absorbing cementing material with high absorption quality of 15-20% can cement aggregate in the carbon-absorbing 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 material 2 The absorption capacity can also be utilized to improve the early strength of the hardened body by utilizing the carbonate reaction, and the method has obvious environmental and social benefits of energy conservation, emission reduction, ecological environment 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 field of building material technology and environmental protection, in particular to a high-carbon-absorption early-strength cementing material based on recycled 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. Absorption of CO by cement-based materials 2 It can reduce carbon emission in building material industry and realize CO 2 Is 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 condition 2 However, 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 is found that compounds other than C 3 S、β-C 2 Gamma-C other than hydraulic calcium silicate such as S 2 S、 CS、C 3 S 2 The non-hydraulic calcium silicate minerals also have excellent carbonation potential, wherein gamma-C 2 S is paid much attention due to low calcium content and high carbonation rate, and is expected to be developed into a carbon-absorbing gelling 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. Recycled concrete powderHas high CaO content and is prepared from C-S-H and Ca (OH) 2 、CaCO 3 The 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 powder 2 The 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 restricted 2 And (4) sintering of S. Therefore, how to fully utilize the high calcium characteristic of the recycled concrete powder to promote CaO and SiO 2 The occurrence of a solid phase reaction with gamma-C 2 The formation of S is the key for preparing the carbon-absorbing gelling material by efficiently utilizing wastes.
Existing CO 2 In curing cement-based materials, the initial porosity of the cement product is generally controlled by the forming pressure. Increased molding pressure, reduced initial porosity of the article, CO 2 The permeation is hindered, the carbonation degree of the material is limited, and the strength development is slow; the molding pressure is reduced, the initial porosity of the product is higher although CO 2 The penetration depth is increased, but the initial porosity of the product is higher and the strength is lower. Therefore, how to increase CO in compact cement products 2 The 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-C 2 And (4) generating S, and preparing the carbon-absorbing gelling material. In addition, according to CO 2 The 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 doping 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 which is CO is formed in a compact cement product 2 The 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:
the high carbon absorption early strength cementing material based on the recycled concrete powder and the biochar, wherein the threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01P+0.13d-0.0014εr 2 Calculation of where V thre Is 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, mu m; 1.1 to 1.5 times of V thre The 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 carbon, rice hull carbon and straw carbon, the average particle size is 50-200 mu m, the porosity is 50-90%, and the average pore size is 0.5-10 mu m.
Further, the carbon-absorbing gelling material prepared from the recycled concrete powder is as follows: according to specific values KH = 0.67-0.70, SM = 2.5-4.0 and IM = 1.5-3.0, 60-90 wt% of recycled concrete powder and 10-40 wt% of siliceous adjusting component are weighed, mixed and ground to the specific surface area of 250-350 m 2 Kg, the powder is ground into the specific surface area of 300-450 m after the gradient temperature rise calcination and cooling 2 /kg, obtaining gamma-C 2 The S content is 55-75 wt% of the carbon-absorbing gelling material.
Further, the CaO content of the recycled concrete powder is 40-80 wt%, and SiO is 2 10-20 wt% of Al 2 O 3 The content is 0-10 wt%.
Further, the siliceous adjusting component is one or more than two of clay brick powder, sludge and glass slag, the CaO content is 0-20 wt%, and SiO is 2 60-80 wt% of Al 2 O 3 The content is 0-20 wt%.
Preferably, the clay brick powder contains 0-10 wt% of CaO and SiO 2 60-80 wt% of Al 2 O 3 The content is 0 to 15 weight percent; the sludge is dried, the water content is controlled to be less than or equal to 2 percent, the CaO content is 0 to 5 weight percent, and SiO is added 2 60-75 wt% of Al 2 O 3 Content (c) of10 to 20 weight percent; the content of CaO in the glass slag is 0 to 15 weight percent, and SiO is 2 60-75 wt% of Al 2 O 3 The content is 0 to 15wt percent.
Further, the gradient temperature-rising calcining and cooling system comprises the following steps: heating to 850-900 ℃ at the speed of 5-30 ℃/min, and keeping the temperature for 0.5-1 h to decompose carbonate and crystallize SiO 2 Activating; then raising the temperature to 1250-1400 ℃ at the speed of 5-30 ℃/min, keeping the temperature for 1-3 h, and ensuring that CaO and SiO are mixed 2 Fully solid-phase reaction to form C 2 S; 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 utilizing beta-C 2 S direction gamma-C 2 The 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 regenerated 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 mixed uniformly, then the high carbon absorption early strength cementing material and the water are mixed uniformly with 2-5 times of aggregate, then the mixture is pressed and formed under the pressure of 2-5 MPa, the mixture is kept stand for 24 hours in a reaction kettle with the relative humidity of 50-70%, and finally the mixture is subjected to CO treatment at the temperature of 20 +/-2 ℃ for 24 hours 2 After 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 2 The absorption quality can reach more than 15 percent of the mass of the carbon-absorbing gelling 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 CO 2 Provides 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 cementitious material prepared in the comparative examples and examples of the invention are recycled concrete powder, clay brick powder, sludge and glass slag, and the chemical compositions of the carbon-absorbing cementitious material 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 m 2 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 then grinding to obtain the powder with the specific surface area of 300-450 m 2 /kg, obtaining gamma-C 2 The S content is 55-75 wt% of the carbon-absorbing gelling material. 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.
Mixing 70-90 wt% of high carbon absorption early strength cementing material and 10-30 wt% of water uniformly, then mixing uniformly with 2-5 times volume of aggregate, then pressing and forming under 2-5 MPa, standing for 24h in a reaction kettle with relative humidity of 50-70%, and finally, CO at 20 +/-2 ℃ for 24h 2 Curing for 24 hours in an environment with the concentration of 20-90% and the relative humidity of 50-70%.
CO in comparative example and example of the present invention 2 The mortar cured for 24 hours is subjected to a compression strength test, and the compression strength is tested according to GB/T17671-1999 cement mortar strength test method (ISO method). By CO 2 The absorption mass represents the carbon absorption performance of the compact cement product, and the calculation formula is as follows:
Figure BDA0003545825380000061
wherein: m is 0 Is CO 2 Dry mortar weight, m, before curing 1 Is CO 2 Dry weight, m, of cured mortar 2 Is the quality of the carbon-absorbing gelling material.
Comparative example 1
Weighing 87.8wt% of recycled concrete powder and 12.2wt% of sludge, mixing and grinding the materials to the specific surface area of 250-350 m 2 Heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1250 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 Kg, to obtain gamma-C 2 The S content of the carbon-absorbing gel material is 56.7 wt%.
Uniformly mixing 87.1wt% of carbon-absorbing gelling material and 12.9wt% 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, standing for 24 hours in a reaction kettle with the relative humidity of 60%, and finally performing CO condensation at the temperature of 20 +/-2 ℃ for 24 hours 2 Curing for 24 hours in an environment with the concentration of 50% and the relative humidity of 60%. Mortar CO thereof 2 The compressive strength is 28.9MPa after 24h of curing, and CO 2 The absorption mass is 9.8 percent of the mass of the carbon-absorbing gel material.
Comparative example 2
Weighing 88.1wt% of recycled concrete powder and 11.9wt% of clay brick powder, mixing and grinding the materials to the specific surface area of 250-350 m 2 /kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1300 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 Kg, to obtain gamma-C 2 The carbon-absorbing gelling material with the S content of 65.2wt percent.
Mixing 86.8wt% of carbon-absorbing gelling material and 13.2wt% 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 hours 2 Curing for 24 hours in an environment with the concentration of 20% and the relative humidity of 50%. Mortar CO thereof 2 The compressive strength is 46.2MPa after 24h of curing, and CO 2 The absorption mass is 4.5 percent of the mass of the carbon-absorbing gel material.
Comparative example 3
Weighing 86.4wt% of recycled concrete powder and 13.6wt% of glass slag, mixing and grinding the materials to the specific surface area of 250-350 m 2 Heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2h; 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 m 2 Kg, to obtain gamma-C 2 The S content of the carbon-absorbing gel material is 71.2 wt%. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47 2 =36.5%, the biochar is straw carbon, the average particle size is 172.42 μm, the porosity is 85.7%, the average pore size is 3.47 μm, and the volume is 0.5 times V thre The 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 83.2wt% of high carbon absorption early strength cementing material and 16.8wt% 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 24h 2 Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof 2 The compressive strength is 34.5MPa after 24h of curing 2 The absorption mass is 8.4 percent of the mass of the carbon-absorbing gel material.
Comparative example 4
Weighing 86.4wt% of recycled concrete powder and 13.6wt% of glass slag, mixing and grinding the materials to the specific surface area of 250-350 m 2 Heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2h; 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 m 2 Kg, to obtain gamma-C 2 The carbon-absorbing gel material with the S content of 71.2wt percent. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47 2 =36.5%, what is, thenThe biochar is used as straw carbon, the average grain diameter 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 V thre The 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 83.2wt% of high carbon absorption early strength cementing material and 16.8wt% 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 24h 2 Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof 2 The compressive strength is 19.4MPa after 24h of curing 2 The absorption mass is 16.9 percent of the mass of the carbon-absorbing gel material.
Example 1
Weighing 87.8wt% of recycled concrete powder and 12.2wt% of sludge, mixing and grinding the materials to the specific surface area of 250-350 m 2 Heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1250 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 /kg, obtaining gamma-C 2 The S content of the carbon-absorbing gel material is 56.7 wt%. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×2.0+0.13×172.42-0.0014×85.7× 3.47 2 =32.5%, the biochar is straw carbon, the average particle size is 172.42 μm, the porosity is 85.7%, the average pore size is 3.47 μm, and the volume is 1.1 times V thre The 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 87.1wt% of high carbon absorption early strength cementing material and 12.9wt% 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 24h 2 Curing for 24 hours in an environment with the concentration of 50% and the relative humidity of 60%. Mortar CO thereof 2 The compressive strength is 52.5MPa after 24h of curing 2 The absorption mass is 15.2 percent of the mass of the carbon-absorbing gel material.
Example 2
Weighing 88.1wt% of recycled concrete powder and 11.9wt% of clay brick powder, mixing and grinding the materials to the specific surface area of 250-350 m 2 /kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1300 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 /kg, obtaining gamma-C 2 The S content of the carbon-absorbing gel material is 65.2 wt%. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×5.0+0.13×172.42-0.0014×85.7 ×3.47 2 =38.5%, the biochar used was straw carbon, the average particle size was 172.42 μm, the porosity was 85.7%, the average pore size was 3.47 μm, and 1.1 times V was added thre The 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 86.8wt% of high carbon absorption early strength cementing material and 13.2wt% of water uniformly, then mixing the high carbon absorption early strength cementing material and 3.8 times of volume of machine-made sand uniformly, pressing and forming the mixture under the pressure of 5.0MPa, standing the mixture in a reaction kettle with the relative humidity of 50% for 24 hours, and finally keeping the mixture at the temperature of 20 +/-2 ℃ and CO for 24 hours 2 Curing for 24 hours in an environment with the concentration of 20% and the relative humidity of 50%. Mortar CO thereof 2 The compressive strength is 61.2MPa after 24h of curing 2 The absorption mass is 15.7 percent of the mass of the carbon-absorbing gel material.
Example 3
Weighing 86.4wt% of recycled concrete powder and 13.6wt% of glass slag, mixing and grinding the materials to the specific surface area of 250-350 m 2 Heating to 900 ℃ at the speed of 10 ℃/min, and keeping the temperature for 0.5h; then heating to 1350 ℃ at the speed of 10 ℃/min, and keeping the temperature for 2h; 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 m 2 Kg, to obtain gamma-C 2 The S content of the carbon-absorbing gel material is 71.2 wt%. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×4.0+0.13×172.42-0.0014×85.7× 3.47 2 =36.5%, the biochar used was straw carbon, the average particle size was 172.42 μm, the porosity was 85.7%, the average pore size was 3.47 μm, and 1.3 times V was added thre Carbon absorption prepared from biochar and recycled concrete powderThe cementing materials are mixed into the high carbon absorption early strength cementing material.
Mixing 83.2wt% of high carbon absorption early strength cementing material and 16.8wt% 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 24h 2 Curing for 24 hours in an environment with the concentration of 40% and the relative humidity of 70%. Mortar CO thereof 2 The compressive strength is 65.3MPa after 24 hours of maintenance 2 The absorption mass is 16.1 percent of the mass of the carbon-absorbing gel material.
Example 4
Weighing 87.3wt% of recycled concrete powder, 4.6wt% of glass slag and 8.1wt% of clay brick powder, mixing and grinding the materials until the specific surface area is 250-350 m 2 /kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1400 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 /kg, obtaining gamma-C 2 The S content is 69.3 percent. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×3.0+0.13× 132.77-0.0014×75.8×1.23 2 =30.6%, the biochar is wood charcoal, the average grain diameter is 132.77 μm, the porosity is 75.8%, the average pore diameter is 1.23 μm, and 1.3 times of V is added thre The 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 86.9wt% of high carbon absorption early strength cementing material and 13.1wt% 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 CO 2 Curing for 24 hours in an environment with the concentration of 70% and the relative humidity of 60%. Mortar CO thereof 2 The compressive strength is 66.7MPa after 24h of maintenance 2 The absorption mass is 17.2 percent of the mass of the carbon-absorbing gel material.
Example 5
Weighing 88.0wt% of recycled concrete powder, 6.2wt% of clay brick powder and 5.8wt% of sludge, mixing and grinding the materials to the specific surface area of 250-350 m 2 /kg, heating to 850 ℃ at the speed of 10 ℃/min, and keeping the temperature for 1h; then heating to 1400 ℃ at the speed of 10 ℃/min, and keeping the temperature for 3h; 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 m 2 /kg, obtaining gamma-C 2 The S content is 67.8 percent. The threshold value of the volume mixing amount of the biochar is V thre ＝7.47+2.01×3.0+0.13× 73.54-0.0014×72.6×2.39 2 =22.5%, selecting biochar as rice husk carbon, with average particle size of 73.54 μm, porosity of 72.6%, average pore diameter of 2.39 μm, and mixing volume of 1.5 times V thre The 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 78.6wt% of high carbon absorption early strength cementing material and 21.4wt% of water uniformly, then mixing with 2.4 times volume of machine-made sand uniformly, pressing and forming under the pressure of 3.0MPa, standing in a reaction kettle with the relative humidity of 60% for 24h, and finally keeping the temperature at 20 +/-2 ℃ and CO for 24h 2 Curing for 24 hours in an environment with the concentration of 90% and the relative humidity of 60%. Mortar CO thereof 2 The compressive strength is 63.7MPa after 24h of curing 2 The absorption mass is 16.8 percent of the mass of the carbon-absorbing gel material.
Comparative example of the invention, example CO 2 The physical properties of the cured high carbon absorption early strength cementitious material are shown in table 2 below.
TABLE 2 comparative and example CO 2 Physical properties of cured high carbon absorption early strength cementitious material
Figure BDA0003545825380000121
Compared with the comparative example 1, the example 1 is added with the biochar, CO, on the basis of the carbon-absorbing gelling material 2 The strength of the mortar is improved from 28.9MPa to 52.5MPa after 24h of maintenance 2 The 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 on the basis of the carbon-absorbing gel material 2 The mortar strength is improved from 46.2MPa to 61.2MPa after 24h of maintenance 2 The absorption quality is improved by 11.2%; mixing with biocharIs 0.5 times V thr Compared with comparative example 3, the biochar mixing amount of example 3 is 1.3 times V thre ， CO 2 The strength of the mortar is improved from 34.5MPa to 65.3MPa after 24h of maintenance 2 The absorption quality is improved from 8.4 percent to 16.1 percent; the mixing amount of the biological carbon and the biological carbon is 3.0 times V thre Comparative example 4 compared to CO of example 3 2 The absorption mass was reduced from 16.9% to 16.1%, but CO 2 The 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 mixing 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 like thre Within 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 promoted 2 The 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, CO 2 The strength of the mortar is 66.7MPa after 24 hours of maintenance 2 The absorption mass is 17.2%; example 5 the biochar used was rice husk charcoal, CO 2 The strength of the mortar is 63.7MPa after 24 hours of maintenance 2 The 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 regenerated concrete powder and the biochar is characterized in that the threshold value of the volume mixing amount of the biochar is V thr ＝7.47+2.01P+0.13d-0.0014εr 2 Calculation of where V thre Is 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, mu m; 1.1 to 1.5 times of V thre High-carbon-absorption early-strength cementing material prepared by mixing biochar and carbon-absorption cementing material prepared from recycled concrete powderAnd (5) feeding.
2. The high carbon absorption early strength cementitious material based on the recycled concrete powder and the biochar as claimed in claim 1, wherein the biochar is more than one of straw carbon, wood carbon and rice husk carbon, the average particle size is 50-200 μm, the porosity is 50-90%, and the average pore size is 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, wherein 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 regulating component, mixing and grinding the mixture to the specific surface area of 250-350 m 2 Kg, the powder is ground into the specific surface area of 300-450 m after the gradient temperature rise calcination and cooling 2 /kg, obtaining gamma-C 2 The S content is 55-75 wt% of the carbon-absorbing gelling material.
4. The high carbon absorption and early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 3, characterized in that the CaO content of the recycled concrete powder is 40-80 wt%, siO 2 10-40 wt% of Al 2 O 3 The content is 0-20 wt%.
5. The high carbon absorption and early strength cementitious material based on recycled concrete powder and biochar as claimed in claim 3, characterized in that the siliceous adjusting component is one or more of clay brick powder, sludge and glass slag, the CaO content of which is 0-20 wt%, siO 2 60-80 wt% of Al 2 O 3 The content is 0-20 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 raising the temperature 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 recited in any one of claims 1 to 6, is characterized by comprising the following steps: mixing the high carbon absorption early strength cementing material with water uniformly, then mixing the high carbon absorption early strength cementing material with 2-5 times volume of aggregate uniformly, then pressing and forming the mixture, standing the mixture in a reaction kettle with the relative humidity of 50-70 percent, and finally keeping the mixture at 20 +/-2 ℃ and CO 2 After 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 CO 2 The 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, characterized in that 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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