CN115745552A - Sponge urban carbon-fixing concrete material based on pore gradient and preparation method thereof - Google Patents
Sponge urban carbon-fixing concrete material based on pore gradient and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a sponge urban carbon-fixing concrete material based on a pore gradient and a preparation method thereof, relates to the technical field of road engineering materials, and particularly relates to a carbon-fixing concrete material and a preparation method thereof. The invention aims to solve the problem that the existing permeable concrete material for the pavement has poor water absorption, water storage and purification functions, and the material is prepared from biochar particles, slag powder, steel slag powder, desulfurized gypsum, phosphogypsum, silicon dioxide, coarse aggregate, fine aggregate and chemical admixture, and the preparation method comprises the following steps: 1. designing biological carbon particles by a pore gradient; 2. forming the material; 3. and (5) maintaining. Micron-level and nano-level pores are introduced into the carbon-fixing concrete material, so that the water absorption and storage capacity of the material is improved; the biochar particles are rich in a large number of active functional groups, organic matters and heavy metals in the water in the road area are effectively adsorbed, the water purification function of the sponge city is realized, and the biochar is sealed in the material, so that the carbon dioxide is prevented from entering an atmosphere, and the carbon emission function is greatly reduced.
Description
Technical Field
The invention relates to the technical field of road engineering materials, in particular to a carbon-fixing concrete material and a preparation method thereof.
Background
With the rapid improvement of the urbanization level of China, urban waterlogging disasters frequently occur in recent years, which not only causes huge economic loss, but also seriously affects the production and life of people and even threatens life safety, and the problem of waterlogging prevention becomes a great test faced by many regional flood seasons. The source of urban inland inundation lies in that the existing rainwater pipe network has low design standard and insufficient drainage capacity on one hand, and the large amount of pavement of the impervious pavement material leads to the reduction of surface water seepage and water storage capacity on the other hand. The construction of the sponge city is a law of the law which solves the problems, and the city has enough elasticity to cope with weather changes through the technical approaches of water absorption, water storage, water seepage, water purification and water slow release, which is also significant for relieving the heat island effect and conserving water resources.
From the perspective of engineering practice, water permeability improvement of pavement is one of the main approaches for realizing urban sponge formation. Unfortunately, the pervious concrete materials widely applied in the current road surface modification project only have good water seepage capability, but almost have no water absorption, water storage and purification functions; therefore, the effects of slowing down the water flow speed, restraining the flood peak and reducing the pressure of a pipe network are not ideal enough, and the elasticity of the sponge city is limited. Such limitations exist because the size distribution of the pores inside the material is not reasonable: the vast majority is communicated macropores with the water seepage function of more than a millimeter level, and the occupation ratio of micron-level and nanometer-level pores with the water absorption and storage functions is small. Therefore, the water absorption, water storage and even water purification capacity of the sponge urban pavement concrete needs to be improved.
Disclosure of Invention
The invention aims to solve the technical problem that the existing permeable concrete material for the pavement has poor water absorption, water storage and water purification functions, and provides a sponge urban carbon-fixing concrete material based on pore gradients and a preparation method thereof.
The sponge urban carbon-fixing concrete material based on the pore gradient is prepared from 100-800 parts of biochar particles, 600-1000 parts of slag powder, 200-500 parts of steel slag powder, 100-250 parts of desulfurized gypsum, 0-100 parts of phosphogypsum, 20-100 parts of silicon dioxide, 1200-1600 parts of coarse aggregate, 0-80 parts of fine aggregate and 0-20 parts of chemical admixture in parts by mass;
the particle diameter of the silicon dioxide is 300-600 nanometers, and the specific surface area is 80-300 m 2 /g。
The slag powder comprises the following main chemical components: caO 40-55%, siO 2 30％-42％，Al 2 O 3 8 to 15 percent of MgO, 3 to 10 percent of MgO and the balance of impurities, and the specific surface area of the catalyst is 150m 2 /kg-650m 2 /kg。
The steel slag powder comprises the following main chemical components: caO 45-55%, siO 2 10％-19％，Al 2 O 3 1 to 5 percent, and the balance of impurities, and the specific surface area of the catalyst is 400m 2 /kg-650m 2 /kg。
The main component of the desulfurized gypsum is dihydrate gypsum with the specific surface area of 200m 2 /kg-500m 2 /kg。
The phosphogypsum has a specific surface area of 200m 2 /kg-500m 2 Per kg of dihydrate gypsum.
The coarse aggregate is composed of two or more of recycled coarse aggregate with the grain diameter of 3-5mm, steel slag fine particles, stones and gravels.
The fine aggregate is two or more of recycled fine aggregate with the particle size of 0.075-2mm, steel slag fine particles, stones and gravels.
The chemical admixture is one or two of polycarboxylate high-efficiency water reducing agent and fatty acid high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent.
The preparation method of the sponge urban carbon sequestration concrete material based on the pore gradient comprises the following steps:
1. pore gradient biochar particles:
drying the biomass waste in an oven at 50-80 ℃ for 24 hours, crushing the biomass waste until the granularity is 5-8 mm, pyrolyzing the biomass waste for 2-5 hours at 300-500 ℃ under an anaerobic condition, taking out the biomass waste, and cooling the biomass waste in the air to obtain biochar particles with a pore structure;
placing the biochar particles in a container, adding 5-25 parts by mass of a pore-forming promoter, mixing at the speed of 250-400 rpm for 5-20 minutes by using magnetic stirring, sealing the container, vacuumizing to reduce the internal pressure to 0.05-0.1MPa, and filtering to obtain the biochar particles with a pore gradient, wherein the pore-forming promoter is a dilute hydrochloric acid solution with the concentration of 1 mol/L;
2. material molding:
dry-stirring and mixing 100-800 parts by mass of biochar particles, 1200-1600 parts by mass of coarse aggregate and 0-80 parts by mass of fine aggregate to obtain a mixture A;
600-1000 parts by mass of slag powder, 200-500 parts by mass of steel slag powder, 100-250 parts by mass of desulfurized gypsum, 0-100 parts by mass of phosphogypsum and 20-100 parts by mass of silicon dioxide are stirred in a dry mode and are fully and uniformly mixed to obtain a mixture B, wherein the particle size of the silicon dioxide is 300-600 nanometers, and the specific surface area of the silicon dioxide is 80-300 m 2 /g；
Adding 0-20 parts by mass of chemical admixture into water, fully and uniformly stirring, then adding the mixture into the mixture B, stirring for 2-5 minutes, adding the mixture A, and stirring for 2-5 minutes again to obtain a mixture, wherein the water amount is 30-50 wt% of the total amount of the mixture;
the chemical admixture is one or two of polycarboxylate high-efficiency water reducing agent and fatty acid high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent;
averagely dividing the stirred mixture into 3 times, pouring the 3 times of the mixture into a mold, keeping the pressure for 20s-30s under the condition that the pressure is 50kN-80kN each time, enabling the thickness of each layer to be 30mm-50mm, and demolding after 3 times of the pressure is finished to obtain the initial material of the sponge urban pavement concrete designed based on the pore gradient;
3. and (5) maintenance:
and (3) placing the initial material of the sponge urban pavement concrete designed based on the pore gradient obtained in the step (II) into a closed curing box, and curing for 10-24 hours under the conditions that the temperature is 25-45 ℃, the relative humidity is 92-95% and the carbon dioxide concentration is 5-99%, so as to obtain the sponge urban carbon-fixing concrete material based on the pore gradient.
Step one, the biomass waste is one or more of fallen leaves, sawdust, wood blocks, rice hulls and straws.
The silicon dioxide is prepared by a gas phase method, is a nano amorphous aggregate generated by high-temperature hydrolysis of silicon tetrachloride in oxyhydrogen flame, and has high pozzolan gelling activity because the surface of the nano amorphous aggregate contains a large amount of silicon hydroxyl groups which are connected with each other through hydrogen bonds.
The preparation method of the coarse aggregate and the fine aggregate comprises the following steps:
1) Putting the waste concrete member into a jaw crusher to obtain massive waste concrete preliminarily;
2) Putting the massive waste concrete into a reaction crusher, and further crushing to obtain granular recycled aggregate;
3) Putting the granular recycled aggregate into mechanical shaping equipment, enabling the recycled aggregate to continuously move at a high speed and generate collision friction to enable cement mortar with loose surface to fall off, and simultaneously polishing to remove needle-shaped edges and corners to obtain the shaped recycled aggregate;
4) Putting the shaped recycled aggregate into a magnetic separator and an eddy current separator, and removing metal impurities of the broken steel bar;
5) Putting the recycled coarse aggregate into a pneumatic separator, and removing broken plastic and wood dust light substances;
6) Putting the recycled coarse aggregate after removing impurities into an ultrasonic cleaning machine to separate stone powder and soil attached to the surface of the recycled coarse aggregate, and then drying the recycled coarse aggregate until the water content is lower than 2%;
7) Soaking the high-quality recycled aggregate in a sodium silicate solution with the mass concentration of 20%, and then drying to obtain a reinforced recycled aggregate;
8) And (3) putting the recycled aggregate into a vibrating screen machine, sorting step by step, taking particles with the diameter of 3-5mm as recycled coarse aggregate, and taking particles with the diameter of 0.075-2mm as recycled fine aggregate.
The pore-forming accelerant is a dilute hydrochloric acid solution with the concentration of 1mol/L, and aims to improve the pore volume and the surface acid group content of the biochar particles, increase the number of micropores so that the biochar particles have reasonable pore distribution, improve the adsorption capacity of the biochar particles on water molecules and ions, and further improve the water storage and purification capacity of the carbon-fixing concrete material.
The chemical admixture can be adsorbed and anchored on cement particles, and the cement particles are dispersed through electrostatic repulsion or steric hindrance effect, so that the flowing and wrapping capacity of slurry is improved, and the slurry is uniformly covered on the surface of the recycled aggregate in the forming process.
The invention introduces a plurality of waste gypsums, wherein the desulfurized gypsums are industrial byproducts of a wet flue gas desulfurization technology adopted in a thermal power plant, the phosphogypsum phosphorus is a byproduct formed in the process of manufacturing a chemical fertilizer, and the main components of the phosphogypsum phosphorus and the chemical fertilizer are dihydrate gypsums. Phosphogypsum phosphorus is a byproduct formed in the process of manufacturing chemical fertilizers, and the main component of the phosphogypsum phosphorus is dihydrate gypsum.
According to the invention, the long-acting carbon sequestration function sponge urban pavement concrete is prepared by mixing biochar particles, a cementing material and sand and stones within a certain particle size range, and then stirring and forming; because the pore gradient distribution is realized in the material, and the biochar particles are rich in a large amount of active functional groups, the water absorption, water storage and water purification functions of the material are obviously improved.
The invention has the beneficial effects that:
1. a large number of micron-sized and nano-sized pores are introduced into the concrete material, so that the water absorption and storage capacity of the material is greatly improved, the urban microclimate is provided, and the urban heat island effect is relieved;
2. the biochar particles are rich in a large number of active functional groups, can effectively adsorb impurities such as organic matters and heavy metals in water in road areas, and realize the water purification function of sponge cities;
3. by sealing the biochar in the material, the carbon dioxide is prevented from entering an atmosphere, so that the carbon emission is greatly reduced.
Drawings
Fig. 1 is a schematic diagram of a sponge urban carbon-fixing concrete material based on a pore gradient obtained in the first experiment.
Detailed Description
The technical solution of the present invention is not limited to the following specific embodiments, but includes any combination of the specific embodiments.
The first embodiment is as follows: the sponge urban carbon-fixing concrete material based on the pore gradient is prepared from 100-800 parts of biochar particles, 600-1000 parts of slag powder, 200-500 parts of steel slag powder, 100-250 parts of desulfurized gypsum, 0-100 parts of phosphogypsum, 20-100 parts of silicon dioxide, 1200-1600 parts of coarse aggregate, 0-80 parts of fine aggregate and 0-20 parts of chemical admixture in parts by mass;
the particle diameter of the silicon dioxide is 300-600 nanometers, and the specific surface area is 80-300 m 2 /g；
The silicon dioxide is prepared by a gas phase method, is a nano amorphous aggregate generated by high-temperature hydrolysis of silicon tetrachloride in oxyhydrogen flame, and has high pozzolan gelling activity because the surface of the nano amorphous aggregate contains a large amount of silicon hydroxyl groups which are connected with each other through hydrogen bonds.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is that the slag powder comprises the following main chemical components: 40-55% of CaO and SiO 2 30％-42％，Al 2 O 3 8-15 percent of MgO, 3-10 percent of MgO and the balance of impurities, and the proportion is shown in the tableArea of 150m 2 /kg-650m 2 In terms of/kg. The rest is the same as the first embodiment.
The third concrete implementation mode: the first or second difference between the embodiment and the specific embodiment is that the steel slag powder mainly comprises the following chemical components: caO 45-55%, siO 2 10％-19％，Al 2 O 3 1 to 5 percent, and the balance of impurities, and the specific surface area of the catalyst is 400m 2 /kg-650m 2 In terms of/kg. The others are the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between the present embodiment and one of the first to third embodiments is that the main component of the desulfurized gypsum is dihydrate gypsum, and the specific surface area of the dihydrate gypsum is 200m 2 /kg-500m 2 (iv) kg. The rest is the same as one of the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is that the phosphogypsum has a specific surface area of 200m 2 /kg-500m 2 /kg of dihydrate gypsum. The rest is the same as one of the first to fourth embodiments.
The sixth specific implementation mode: the difference between the present embodiment and one of the first to fifth embodiments is that the coarse aggregate is composed of two or more of recycled coarse aggregate having a particle size of 3 to 5mm, fine steel slag particles, stones, and sand. The rest is the same as one of the first to fifth embodiments.
In the present embodiment, when the coarse aggregate is a composition, the ratio of the components is arbitrary.
The seventh embodiment: the difference between the first embodiment and the sixth embodiment is that the fine aggregate is composed of two or more of recycled fine aggregate with the particle size of 0.075-2mm, steel slag fine particles, stones and sand stones. The rest is the same as one of the first to sixth embodiments.
In the case where the fine aggregate is a composition in the present embodiment, the ratio of the components is arbitrary.
The specific implementation mode is eight: the difference between the first embodiment and the seventh embodiment is that the chemical admixture is one or two of a polycarboxylate-based superplasticizer and a fatty acid-based superplasticizer;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent. The rest is the same as one of the first to seventh embodiments.
When the chemical admixture according to the present embodiment is a composition, the ratio of the components is arbitrary.
The specific implementation method nine: the preparation method of the sponge urban carbon sequestration concrete material based on the pore gradient comprises the following steps:
1. pore gradient biochar particles:
drying the biomass waste in an oven at 50-80 ℃ for 24 hours, crushing the biomass waste until the granularity is 5-8 mm, pyrolyzing the biomass waste for 2-5 hours at 300-500 ℃ under an anaerobic condition, taking out the biomass waste, and cooling the biomass waste in air to obtain biochar particles with a pore structure;
putting the biochar particles into a container, adding 5-25 parts by mass of a pore-forming promoter, mixing for 5-20 minutes at the speed of 250-400 rpm by using magnetic stirring, sealing the container, vacuumizing to reduce the internal pressure to 0.05-0.1MPa, filtering to obtain biochar particles with a pore gradient,
the pore-forming accelerant is a dilute hydrochloric acid solution with the concentration of 1 mol/L;
2. material molding:
dry-stirring and mixing 100-800 parts by mass of biochar particles, 1200-1600 parts by mass of coarse aggregate and 0-80 parts by mass of fine aggregate to obtain a mixture A;
600-1000 parts by mass of slag powder, 200-500 parts by mass of steel slag powder, 100-250 parts by mass of desulfurized gypsum, 0-100 parts by mass of phosphogypsum and 20-100 parts by mass of silicon dioxide are stirred in a dry mode and are fully and uniformly mixed to obtain a mixture B, wherein the particle size of the silicon dioxide is 300-600 nanometers, and the specific surface area of the silicon dioxide is 80-300 m 2 /g；
Adding 0-20 parts by mass of chemical additive into water, fully and uniformly stirring, then adding the mixture into the mixture B, stirring for 2-5 minutes, adding the mixture A, and stirring for 2-5 minutes again to obtain a mixture, wherein the water amount is 30-50 wt% of the total amount of the mixture;
the chemical admixture is one or two of polycarboxylate high-efficiency water reducing agent and fatty acid high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent;
averagely dividing the stirred mixture into 3 times, pouring the 3 times of the mixture into a mold, keeping the pressure for 20s-30s under the condition that the pressure is 50kN-80kN each time, enabling the thickness of each layer to be 30mm-50mm, and demolding after 3 times of the pressure is finished to obtain the initial material of the sponge urban pavement concrete designed based on the pore gradient;
3. and (5) maintenance:
and (3) placing the initial material of the sponge urban pavement concrete designed based on the pore gradient obtained in the step (II) into a closed curing box, and curing for 10-24 hours under the conditions that the temperature is 25-45 ℃, the relative humidity is 92-95% and the carbon dioxide concentration is 5-99%, so as to obtain the sponge urban carbon-fixing concrete material based on the pore gradient. .
The detailed implementation mode is ten: the difference between this embodiment and the ninth embodiment is that step one, the biomass waste is one or more of fallen leaves, wood chips, wood blocks, rice hulls and straws. The rest is the same as in the ninth embodiment.
The concrete implementation mode eleven: the difference between the embodiment and the ninth embodiment is that the preparation method of the sponge urban carbon sequestration concrete material based on the pore gradient is as follows:
1. designing the biochar particles by using a pore gradient:
drying the biomass waste in an oven at 50-70 ℃ for 24 hours, crushing the biomass waste until the granularity is 5-8 mm, pyrolyzing the biomass waste for 1-3 hours at 350-450 ℃ under an anaerobic condition, taking out the biomass waste, and cooling the biomass waste in air to obtain biochar particles with a pore structure;
putting the biochar particles into a container, adding 5-25 parts by mass of a pore-forming promoter, mixing for 5-20 minutes at the speed of 250-400 rpm by using magnetic stirring, sealing the container, vacuumizing to reduce the internal pressure to 0.05-0.1MPa, filtering to obtain the biochar particles with a pore gradient,
the pore-forming accelerant is a dilute hydrochloric acid solution with the concentration of 1 mol/L;
2. material molding:
carrying out dry stirring and mixing on 400-800 parts by mass of biochar particles and 1200-1400 parts by mass of coarse aggregate to obtain a mixture A;
600-1000 parts by mass of slag powder, 200-500 parts by mass of steel slag powder, 100-250 parts by mass of desulfurized gypsum, 0-100 parts by mass of phosphogypsum and 20-100 parts by mass of silicon dioxide are stirred in a dry mode and are fully and uniformly mixed to obtain a mixture B, wherein the particle size of the silicon dioxide is 300-600 nanometers, and the specific surface area of the silicon dioxide is 80-300 m 2 /g；
Adding 0-20 parts by mass of chemical additive into water, fully and uniformly stirring, then adding the mixture into the mixture B, stirring for 2-5 minutes, adding the mixture A, and stirring for 2-5 minutes again to obtain a mixture, wherein the water amount is 30-38 wt% of the total amount of the mixture;
the chemical admixture is one or two of polycarboxylate high-efficiency water reducing agent and fatty acid high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent;
evenly dividing the stirred mixture into 3 times, pouring the mixture into a mould, keeping the pressure for 20s-30s under the condition of 50kN-80kN each time, pressing the mixture to a thickness of 30mm-50mm each time, and demoulding after 3 times to obtain the initial material of the sponge city pavement concrete designed based on the pore gradient;
3. and (5) maintenance:
and (3) placing the initial material of the sponge urban pavement concrete designed based on the pore gradient obtained in the step (II) into a closed curing box, and curing for 10-24 hours under the conditions that the temperature is 25-45 ℃, the relative humidity is 92-95% and the carbon dioxide concentration is 5-99%, so as to obtain the sponge urban carbon-fixing concrete material based on the pore gradient.
The following experiments are adopted to verify the effect of the invention:
experiment one:
the preparation method of the sponge urban carbon-fixing concrete material based on the pore gradient comprises the following steps:
1. pore gradient biochar particles:
drying the biomass waste in an oven at 60 ℃ for 24 hours, crushing the biomass waste until the granularity is 6 mm, pyrolyzing the biomass waste for 3 hours at 500 ℃ under an anaerobic condition, taking out the biomass waste, and cooling the biomass waste in air to obtain biochar particles with a pore structure;
placing the biochar particles in a container, adding 25 parts by mass of a pore-forming promoter, mixing at the speed of 250 revolutions per minute for 10 minutes by using magnetic stirring, sealing the container, vacuumizing to reduce the internal pressure to 0.05MPa, and filtering to obtain the biochar particles with a pore gradient, wherein the pore-forming promoter is a dilute hydrochloric acid solution with the concentration of 1 mol/L;
2. material molding:
carrying out dry stirring and mixing on 300 parts by mass of biochar particles, 1300 parts by mass of coarse aggregate and 50 parts by mass of fine aggregate to obtain a mixture A;
800 parts by mass of slag powder, 300 parts by mass of steel slag powder, 200 parts by mass of desulfurized gypsum, 50 parts by mass of phosphogypsum and 80 parts by mass of silicon dioxide are stirred in a dry mode and are fully and uniformly mixed to obtain a mixture B, wherein the particle size of the silicon dioxide is 300-600 nanometers, and the specific surface area of the silicon dioxide is 80-300 m 2 /g；
Adding 5 parts by mass of a chemical additive into water, fully and uniformly stirring, then adding the mixture into the mixture B, stirring for 2-5 minutes, adding the mixture A, and stirring for 3 minutes again to obtain a mixture, wherein the water amount is 35wt% of the total amount of the mixture;
the chemical additive is a polycarboxylate high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
averagely dividing the stirred mixture into 3 times, pouring the 3 times of mixture into a mould, keeping the pressure for 30s under the condition of 60kN each time, enabling the thickness of each layer to be 40mm, and demoulding after 3 times of operation to obtain the sponge city pavement concrete initial material based on the pore gradient design;
3. and (5) maintenance:
and (3) placing the initial material of the sponge urban pavement concrete based on the pore gradient design obtained in the step (II) into a closed curing box, and curing for 16 hours under the conditions that the temperature is 30 +/-1 ℃, the relative humidity is 92% and the carbon dioxide concentration is 90 +/-2%, so as to obtain the sponge urban carbon-fixing concrete material based on the pore gradient.
Step one, the biomass waste is one or more of fallen leaves, sawdust, wood blocks, rice hulls and straws.
The particle diameter of the silicon dioxide is 300-600 nanometers, and the specific surface area is 80-300 m 2 /g。
The slag powder comprises the following main chemical components: caO 40%, siO 2 30％，Al 2 O 3 8%, mgO3%, and the balance of impurities, and the specific surface area of the alloy is 150m 2 /kg。
The steel slag powder comprises the following main chemical components: caO 45% -, siO 2 10％，Al 2 O 3 1% and the balance impurities, and the specific surface area is 400kg.
The main component of the desulfurized gypsum is dihydrate gypsum, and the specific surface area of the desulfurized gypsum is 200-500m 2 /kg。
The phosphogypsum has a specific surface area of 200m 2 /kg-500m 2 Per kg of dihydrate gypsum.
The coarse aggregate is composed of recycled coarse aggregate with the grain size of 3-5mm, steel slag fine particles, stones and sandstone, wherein the ratio of the components is arbitrary.
The fine aggregate is composed of recycled fine aggregate with the particle size of 0.075-2mm, steel slag fine particles, stones and sandstone, wherein the ratio of the components is arbitrary.
The preparation method of the coarse aggregate and the fine aggregate comprises the following steps:
1) Putting the waste concrete member into a jaw crusher to preliminarily obtain blocky waste concrete;
2) Putting the massive waste concrete into a reaction crusher, and further crushing to obtain granular recycled aggregate;
3) Putting the granular recycled aggregate into mechanical shaping equipment, enabling the recycled aggregate to continuously move at a high speed and generate collision friction to enable cement mortar with loose surface to fall off, and simultaneously polishing to remove needle-shaped edges and corners to obtain the shaped recycled aggregate;
4) Putting the reshaped recycled aggregate into a magnetic separator and an eddy current separator to remove metal impurities in the broken steel bars;
5) Feeding the recycled coarse aggregate into a pneumatic separator, and removing broken plastics and light wood dust substances;
6) Putting the recycled coarse aggregate after removing impurities into an ultrasonic cleaning machine to separate stone powder and soil attached to the surface of the recycled coarse aggregate, and then drying the recycled coarse aggregate until the water content is lower than 2%;
7) Soaking the high-quality recycled aggregate in a sodium silicate solution with the mass concentration of 20%, and then drying to obtain a reinforced recycled aggregate;
8) And (3) putting the recycled aggregate into a vibrating screen machine, sorting step by step, taking particles with the diameter of 3-5mm as recycled coarse aggregate, and taking particles with the diameter of 0.075-2mm as recycled fine aggregate.
Under the condition of the same water permeability coefficient, compared with the conventional permeable concrete, the sponge urban carbon-fixing concrete material based on the pore gradient prepared by the experiment has the advantages that the saturated water absorption capacity is improved by more than 50%, and meanwhile, the sponge urban carbon-fixing concrete material has a stronger adsorption effect on heavy metal ions in urban sewage, so that the water storage capacity and the water purification capacity are obviously improved.
Claims (10)
1. The sponge urban carbon-fixing concrete material based on the pore gradient is characterized by being prepared from 100-800 parts of biochar particles, 600-1000 parts of slag powder, 200-500 parts of steel slag powder, 100-250 parts of desulfurized gypsum, 0-100 parts of phosphogypsum, 20-100 parts of silicon dioxide, 1200-1600 parts of coarse aggregate, 0-80 parts of fine aggregate and 0-20 parts of chemical admixture in parts by mass;
the particle diameter of the silicon dioxide is 300-600 nanometers, and the specific surface area is 80-300 m 2 /g。
2. The pore gradient-based sponge urban carbon sequestration concrete material according to claim 1, characterized in that the slag powder comprises the following main chemical components: caO 40-55%, siO 2 30％-42％，Al 2 O 3 8 to 15 percent of MgO, 3 to 10 percent of MgO and the balance of impurities, and the specific surface area of the catalyst is 150m 2 /kg-650m 2 /kg。
3. The pore gradient-based sponge urban carbon sequestration concrete material according to claim 1, characterized in that the steel slag powder comprises the following main chemical components: caO 45-55%, siO 2 10％-19％，Al 2 O 3 1 to 5 percent, and the balance of impurities, and the specific surface area of the catalyst is 400m 2 /kg-650m 2 /kg。
4. The pore gradient-based sponge urban carbon-fixing concrete material according to claim 1, characterized in that the desulfurized gypsum is mainly composed of dihydrate gypsum with a specific surface area of 200m 2 /kg-500m 2 /kg。
5. The pore gradient-based sponge urban carbon sequestration concrete material according to claim 1, characterized in that the phosphogypsum has a specific surface area of 200m 2 /kg-500m 2 /kg of dihydrate gypsum.
6. The sponge urban carbon-fixing concrete material based on the pore gradient as claimed in claim 1, characterized in that the coarse aggregate is composed of two or more of recycled coarse aggregate with the particle size of 3-5mm, steel slag fine particles, stones and gravels.
7. The sponge urban carbon sequestration concrete material based on pore gradient according to claim 1, characterized in that the fine aggregate is composed of two or more of recycled fine aggregate with a particle size of 0.075-2mm, steel slag fine particles, stones and gravels.
8. The sponge urban carbon-fixing concrete material based on the pore gradient according to claim 1, characterized in that the chemical admixture is one or two of a polycarboxylate-type high-efficiency water reducing agent and a fatty acid-type high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent.
9. The preparation method of the sponge urban carbon-fixing concrete material based on the pore gradient as claimed in claim 1 is characterized in that the preparation method of the sponge urban carbon-fixing concrete material based on the pore gradient is as follows:
1. pore gradient biochar particles:
drying the biomass waste in an oven at 50-80 ℃ for 24 hours, crushing the biomass waste until the granularity is 5-8 mm, pyrolyzing the biomass waste for 2-5 hours at 300-500 ℃ under an anaerobic condition, taking out the biomass waste, and cooling the biomass waste in air to obtain biochar particles with a pore structure;
placing the biochar particles in a container, adding 5-25 parts by mass of a pore-forming promoter, mixing at the speed of 250-400 rpm for 5-20 minutes by using magnetic stirring, sealing the container, vacuumizing to reduce the internal pressure to 0.05-0.1MPa, and filtering to obtain the biochar particles with a pore gradient, wherein the pore-forming promoter is a dilute hydrochloric acid solution with the concentration of 1 mol/L;
2. material molding:
dry-stirring and mixing 100-800 parts by mass of biochar particles, 1200-1600 parts by mass of coarse aggregate and 0-80 parts by mass of fine aggregate to obtain a mixture A;
600-1000 parts by mass of slag powder, 200-500 parts by mass of steel slag powder, 100-250 parts by mass of desulfurized gypsum, 0-100 parts by mass of phosphogypsum and 20-100 parts by mass of silicon dioxide are stirred in a dry mode and are fully and uniformly mixed to obtain a mixture B, wherein the particle size of the silicon dioxide is 300-600 nanometers, and the specific surface area of the silicon dioxide is 80-300 m 2 /g；
Adding 0-20 parts by mass of chemical additive into water, fully and uniformly stirring, then adding the mixture into the mixture B, stirring for 2-5 minutes, adding the mixture A, and stirring for 2-5 minutes again to obtain a mixture, wherein the water amount is 30-50 wt% of the total amount of the mixture;
the chemical admixture is one or two of polycarboxylate high-efficiency water reducing agent and fatty acid high-efficiency water reducing agent;
the polycarboxylate high-efficiency water reducing agent is a liquid substance with the solid content of 40% obtained by free radical polymerization reaction of allyl polyoxyethylene ether and maleic anhydride copolymer;
the fatty acid series high-efficiency water reducing agent is a sulfonated acetone-formaldehyde condensate with the solid content of 30 percent;
averagely dividing the stirred mixture into 3 times, pouring the 3 times of the mixture into a mold, keeping the pressure for 20s-30s under the condition that the pressure is 50kN-80kN each time, enabling the thickness of each layer to be 30mm-50mm, and demolding after 3 times of the pressure is finished to obtain the initial material of the sponge urban pavement concrete designed based on the pore gradient;
3. and (5) maintenance:
and (3) placing the initial material of the sponge urban pavement concrete designed based on the pore gradient obtained in the step (II) into a closed curing box, and curing for 10-24 hours under the conditions that the temperature is 25-45 ℃, the relative humidity is 92-95% and the carbon dioxide concentration is 5-99%, so as to obtain the sponge urban carbon-fixing concrete material based on the pore gradient.
10. The method for preparing the sponge urban carbon-fixing concrete material based on the pore gradient according to the claim 9, characterized in that the biomass waste in the step one is one or more of fallen leaves, wood chips, wood blocks, rice hulls and straws.
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| CN110683774A (en) * | 2019-10-23 | 2020-01-14 | 迁安威盛固废环保实业有限公司 | Cementing material taking slag-steel slag-gypsum as raw material and preparation method thereof |
| CN114804734A (en) * | 2022-04-13 | 2022-07-29 | 诚邦生态环境股份有限公司 | Biopolymer water-permeable concrete brick containing biomass charcoal |
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