CN108975791B - Regenerative aerated concrete with excellent freezing resistance and preparation method thereof - Google Patents
Regenerative aerated concrete with excellent freezing resistance and preparation method thereof Download PDFInfo
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- CN108975791B CN108975791B CN201811018881.4A CN201811018881A CN108975791B CN 108975791 B CN108975791 B CN 108975791B CN 201811018881 A CN201811018881 A CN 201811018881A CN 108975791 B CN108975791 B CN 108975791B
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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
- 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
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/0022—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors
- C04B38/0025—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors starting from inorganic materials only, e.g. metal foam; Lanxide type products
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/40—Porous or lightweight materials
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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
- 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
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Abstract
The regenerative aerated concrete with excellent frost resistance comprises the following raw materials of a main material, an auxiliary additive and a dispersion medium, wherein the main material comprises the following components in percentage by weight: 20-35% of fly ash, 20-35% of furnace slag, 10-20% of desulfurized ash and 10-25% of cement; the auxiliary additive comprises aluminum powder, a foam stabilizer and an early strength agent, and the addition amounts of the aluminum powder, the foam stabilizer and the early strength agent are respectively 0.1-0.2%, 0.45-0.55% and 0.45-0.60% of the mass of the main material; the dispersion medium is power plant wastewater, and the water-material ratio of the power plant wastewater to the main material and the auxiliary additive is 0.55-0.60. The invention adopts the fixed wastes such as fly ash, furnace slag and the like of a power plant and wastewater as raw materials, prepares the aerated concrete with excellent frost resistance, long service life and good comprehensive performance by unique preparation process and raw material formula adjustment, realizes the resource utilization of the wastes and improves the economic benefit.
Description
Technical Field
The invention relates to the technical field of aerated concrete preparation, in particular to a method for preparing aerated concrete with excellent frost resistance by using solid waste and wastewater of a power plant as main raw materials.
Background
The aerated concrete is a light porous building material, which is prepared by using cement, lime, slag, river sand, gas-forming material and the like as raw materials through the working procedures of grinding, proportioning, pouring, cutting, autoclaved curing, milling and grinding and the like. The aerated concrete is named as aerated concrete because the aerated product contains a large amount of uniform and fine air holes. The aerated concrete has the advantages of light weight, good heat preservation performance, good processability and the like, and is one of novel light building materials which are most widely used and are earliest to be popularized and applied in China. The aerated concrete can be used for manufacturing building blocks, heat-insulating and filling materials, roof wall boards, heat-insulating pipes and other products. Therefore, the aerated concrete products are widely applied to industrial and civil buildings and are mainly used in light wall board materials at present. The aerated concrete material has the advantages, so that the aerated concrete material is well applied and developed at home and abroad.
In the daily power generation production process of a power plant, a large amount of solid wastes such as furnace slag, fly ash and the like and wastewater can be produced by a boiler, and the subsequent processing, utilization and reprocessing of the wastes are the key points for obtaining better social benefits, economic benefits and environmental protection benefits in the power plant production.
At present, the aerated concrete produced in the prior art needs to buy and consume a large amount of excitants to ensure that the finished product aerated concrete has proper density, certain strength and bearing capacity. Moreover, a large amount of water resources are consumed in the production process of the aerated concrete. The production cost of the aerated concrete is relatively high, and the production and the utilization of the aerated concrete are limited. Meanwhile, the existing aerated concrete has the defect of relatively poor frost resistance, when the aerated concrete is used for buildings in extremely cold regions, due to the freezing and thawing circulation effect of water in the structure, cracks and peeling are easy to generate in the aerated concrete material, so that the strength of the aerated concrete block is reduced, and the service life is shortened.
Disclosure of Invention
The technical purpose of the invention is as follows: the aerated concrete with excellent frost resistance, long service life and good comprehensive performance is prepared by adopting the fixed wastes such as fly ash and slag of a power plant and waste water as raw materials and adjusting a unique preparation process and a raw material formula, so that the resource utilization of the wastes is realized, and the economic benefit is improved.
In order to solve the technical problems, the invention adopts the technical scheme that: the regenerative aerated concrete with excellent frost resistance comprises main materials, auxiliary additives and a dispersion medium, wherein the main materials comprise the following components in percentage by weight: 20-35% of fly ash, 20-35% of furnace slag, 10-20% of desulfurized ash and 10-25% of cement; the auxiliary additive comprises aluminum powder, a foam stabilizer and an early strength agent, and the addition amounts of the aluminum powder, the foam stabilizer and the early strength agent are respectively 0.1-0.2%, 0.45-0.55% and 0.45-0.60% of the mass of the main material; the dispersion medium is power plant wastewater, and the water-material ratio of the power plant wastewater to the main material and the auxiliary additive is 0.55-0.60.
Further, the mass concentration of sodium sulfate in the power plant wastewater is 5-6%.
A preparation process of regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 1.5-2.5 h, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90% for later use;
step three, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, putting the mixture into a stirrer, stirring and mixing for 4-7 min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer and an early strength agent, and continuously stirring for 30-60 s to prepare casting slurry for later use;
step four, pouring the casting slurry prepared in the step three into a mold, placing the mold into a curing box at the temperature of 50-60 ℃ for curing for 2-4 hours, and then demolding to prepare a module for later use;
step five, cutting the module prepared in the step four by a cutting machine according to a preset size to prepare a sample for later use;
and step six, putting the sample cut in the step five into a still kettle, and performing steam curing for 12-18 hours at 190-210 ℃ and under 10-12 MPa to obtain the finished product of the aerated concrete.
Further, in the fourth step, the casting slurry stirred in the third step is poured into the mold within 60 seconds.
Further, in the third step, the rotating speed of the stirrer is 2000-3000 r/min.
Furthermore, the auxiliary additive also comprises pretreated carbon powder.
Further, the addition amount of the pretreated carbon powder is 0.2-0.3% of the mass of the main material.
Further, the processing steps of the pretreated carbon powder are as follows:
a. taking activated carbon, and crushing the activated carbon into powder with the particle size of 20-30 microns for later use;
b. adding sodium carbonate into water to prepare a sodium carbonate solution with the mass concentration of 50-60 g/L for later use;
c. and (c) immersing the activated carbon powder prepared in the step (a) into the sodium carbonate solution prepared in the step (b), carrying out immersion type soaking treatment for 30-60 min, taking out, drying in a drying oven at the temperature of 40-50 ℃, fully drying to finish the pretreatment of the carbon powder, and storing in vacuum for later use.
Further, in the sixth step, before the sample is put into the still kettle for steaming, the sample is put into a microwave inductor and is processed for 120-180 s under the power condition of 200-300W.
Has the advantages that:
1. the invention adopts the inherent wastes of power plants such as furnace slag, fly ash, power plant wastewater and the like as raw materials to prepare the aerated concrete, the raw materials have wide sources, low price and easy obtainment and convenient processing, not only greatly reduces the production cost of the aerated concrete and has stronger market competitiveness, but also develops a new recycling way for the solid wastes and wastewater of coal-fired thermal power plants, and well meets the modern production requirements of energy conservation and environmental protection. Meanwhile, the prepared aerated concrete not only can meet the national standard requirements of hardness, compressive strength, volume density and the like, but also has excellent frost resistance, long service life, and good economic benefit, and is particularly suitable for being used in cold environments.
2. In the preparation process of the aerated concrete, the invention fully utilizes the gelling property of the desulfurized fly ash and the reaction activity of a small amount of free lime contained in the desulfurized fly ash, and well solves the influence of the free lime on the stability of the finished product aerated concrete through the ball milling and crushing operation. Meanwhile, under the autoclaved condition of 190-210 ℃ and 10-12 MPa, the incompletely reacted free lime can also be subjected to volcanic ash reaction with substances such as fly ash and quartz under the excitation action of alkaline substances in the power plant wastewater to generate a high-strength compound with a gelling property, so that the bonding strength of a blank body is improved, and the finished aerated concrete has excellent compressive strength.
3. The method adopts the power plant wastewater containing rich sodium sulfate as the activator, thereby saving water resources, avoiding the purchase and consumption of the alkaline activator, saving the production cost and finding a new utilization way for the desulfurization wastewater of the power plant.
4. In the preparation process of the aerated concrete, a certain amount of activated carbon powder pretreated by a sodium carbonate solution is added into an auxiliary additive. In the pretreatment step of the activated carbon powder, the activated carbon powder has relatively small volume through the crushing step, and then is soaked for a long time, so that the sodium carbonate is dissolved, infiltrated and adsorbed into the internal micropore gap structure of the activated carbon powder, and is separated out, crystallized and surface-coated in micropores in the subsequent drying process. In the subsequent microwave treatment step of the activated carbon powder after sodium carbonate pretreatment, the sodium carbonate coated in the micropores and on the surface can catalyze and reinforce the combustion and gasification process of the activated carbon powder by reducing the activation energy of carbon-oxygen reaction in the process of microwave high-temperature combustion of the activated carbon, so that more tiny, uniform and dense blasting pores are quickly formed inside the aerated concrete, and the finished aerated concrete has smaller volume density, better heat preservation and frost resistance. This is because: the sodium carbonate is absorbed in the micropores of the activated carbon to distort the crystal lattice of the carbon atoms, so that the activated carbon is activatedIncrease, accelerate C3O4Is formed and decomposed to C3O4Is easier to be separated from crystal lattice and decomposed into CO and CO2And the CO generated can be reacted with C3O4Impact to make C3O4Further decomposition is accelerated. At the same time, part of sodium carbonate can be decomposed into Na at high temp 20 and CO2，Na2The high temperature sublimation of 0 causes the carbon particles to become relatively loose in structure, further exacerbating the combustion of the carbon. Namely: the addition of activated carbon powder pretreated by a sodium carbonate solution and the microwave treatment operation after steam curing enable a large number of uniform and compact micro pores to be formed inside the aerated concrete, the formation of the micro pores not only reduces the volume density of the aerated concrete to make the aerated concrete lighter, but also enables the internal pores to be more numerous to form spacing layers and the thermal insulation performance to be better, and the dissolution and permeation effect of the carbon powder during high-temperature blasting enables hard mullite crystal phases to be formed around the micro pores, so that the compressive strength and frost resistance of the finished aerated concrete are improved.
5. In the preparation process of the aerated concrete, the water-material ratio of 0.55-0.60 in the raw materials is limited, which is discovered by the inventor through a large amount of experimental researches. Under the water-material ratio, the slurry has sufficient water to ensure the hydration reaction of the slurry, the reaction is more sufficient, the thickening speed of the slurry is relatively high, the internal and external densities of the product are relatively uniform, and the residual water in the hardened product is less, so that the capillary pores formed by the excessive water are less, and the product is relatively compact and has higher lightness. Meanwhile, under the limit of the water-material ratio, the thickening speed of the slurry is synchronous with the gas generating speed of the aluminum powder, so that the gas generation phenomenon caused by non-uniform gas generation can be avoided, and the air holes in the aerated concrete are uniformly distributed and uniform in size, and have smaller subsequent shrinkage deformation and higher compressive strength.
Drawings
FIG. 1 is an X-ray diffraction pattern of fly ash (ash # 1);
FIG. 2 is an X-ray diffraction pattern of slag (slag # 1);
FIG. 3 is an X-ray diffraction pattern of desulfurized fly ash (desulfurized fly ash # 3);
FIG. 4 is an X-ray diffraction characterization spectrum of the raw materials before co-milling;
FIG. 5 is an X-ray diffraction characterization map of the finished aerated concrete;
FIG. 6 is a photograph of a finished aerated concrete product;
FIG. 7 is a photograph of a pile of finished aerated concrete;
FIG. 8 is a picture of the microstructure of the finished aerated concrete at 500 μm;
FIG. 9 is a photograph of the microstructure of the finished aerated concrete at 20 μm.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
the invention uses solid wastes of power plants such as fly ash, desulfurized ash and the like as main raw materials, and uses the waste water of the power plants as a dispersion medium and an excitant to prepare the aerated concrete, so that the product meets the performance specified by the national standard, simultaneously achieves the aim of fully utilizing the solid wastes and the waste water of the power plants, realizes the resource utilization of the wastes, saves industrial water, has low cost and excellent freezing resistance, and has stronger market competitiveness.
The basic principle of preparing the aerated concrete is as follows: the power plant fly ash has potential volcanic ash characteristics, the desulfurized fly ash has gelling characteristics, and free lime which is not completely reacted in the desulfurized fly ash can be subjected to volcanic ash reaction with fly ash, quartz and other substances under the excitation action of alkaline substances through steam pressure action to generate substances with gelling characteristics, so that the bonding strength of a blank body is improved. If metal aluminum powder is introduced into the ingredients as a gas former, the aluminum powder, water and hydroxide react to generate gases such as hydrogen and the like under the action of alkali excitation, so that the blank is foamed, and the aerated concrete is obtained. As the waste water of the power plant desulfurization process contains more than 3wt% of sodium sulfate, the waste water is used as a dispersion medium, and an additional alkaline activator is not needed. According to a proper material proportion, fly ash, slag and desulfurized ash of a power plant are taken as main raw materials, a certain amount of auxiliary additives such as portland cement, aluminum powder, a coagulant, a foam stabilizer and the like are added, power plant wastewater containing sodium sulfate with a certain concentration is taken as a dispersion medium, and the aerated concrete can be obtained through a certain technological process.
The main reaction process is as follows:
2Al+3Ca(OH)2+6H2O→3CaO·Al2O3·6H2O+3H2↑
2Al+6H2O→2 Al(OH)3+H2↑
2Al+3Ca(OH)2+3 CaSO4·2H2O+mH2O→3CaO·Al2O3·CaSO4·n H2O+3H2↑
the main chemical reactions when the slurry is solidified are as follows:
C3S+mH2O→Ca(OH)2+ C2SHn
C3S+mH2O→C2SHn
C3S+mH2O→C3AH6
C4AF+mH2O→C3AH6+ CFH
C3AH6+Ca(OH)2+mH2O→C4AH12
C4AH12+3 CaSO4·2H2O+mH2O→Ca(OH)2+C3A·3 CaSO4·n H2O
the aerated concrete prepared by the invention meets the corresponding national standard, has obvious frost resistance and also has the following advantages:
(1) the main raw materials are power plant slag, fly ash, desulfurized fly ash and wastewater, and a utilization way is developed for solid waste and wastewater of a coal-fired power plant.
(2) As the main raw materials are power plant wastes, the raw materials are low in cost and low in manufacturing cost, and have strong market competitiveness.
(3) The gelling property of the desulfurized fly ash and the reactivity of the free lime in the desulfurized fly ash are fully utilized, and the influence of the free lime on the stability is well solved by grinding.
(4) The sodium sulfate contained in the power plant wastewater is used as an exciting agent, so that the cost is saved, and a new utilization way is found for the power plant desulfurization wastewater.
The raw material of the invention is solid waste provided by a boiler of Luoyang oil refining chemical company Limited. The fly ash is 1# ash in the solid waste of the power station, the furnace slag is 1# slag in the solid waste of the power station, and the desulfurized ash is 3# desulfurized ash generated by the electric shovel power station. The basic characteristics of the raw materials used are as follows:
table 1 shows the chemical composition of the 1# ash, which is seen to consist mainly of SiO2、Al2O3、CaO、Fe2O3、K2O and TiO2Etc., and in addition should contain a certain amount of carbon components. FIG. 1 shows an X-ray diffraction pattern of gray # 1. As can be seen from FIG. 1, the 1# ash has a crystalline phase composition mainly consisting of quartz, mullite and hematite, and the three crystalline phase minerals are precipitates of molten slag during the cooling process. There are large noncells in the diffractogram at diffraction angles between 20 ° and 30 °, indicating a higher amorphous glass phase in the ash.
Chemical composition of Ash # Table 11 (%)
The chemical composition and the X-ray diffraction pattern of the slag No. 1 are shown in Table 2 and attached FIG. 2, respectively, and the chemical composition and the phase composition are closer to those of the ash No. 1. The X-ray diffraction pattern also contains more prominent non-unit cells. The difference is that the ash may contain a higher carbon content, while the slag has a lower carbon content.
TABLE 21 chemical composition of slag (%)
Table 3 gives the chemical composition analysis of the desulfurized ash # 3. As can be seen from Table 3, the desulfurized fly ash consists mainly of SO3、CaO、SiO2、Al2O3、Fe2O3MgO, in which CaO and SO3This is high because the sulfur in the coal overflows mainly in a gaseous phase, and reacts with lime to form gypsum. FIG. 3 shows an X-ray diffraction pattern of desulfurized fly ash, which can be seen from FIG. 3, wherein the desulfurized fly ash has the main crystal phases of limestone, gypsum, calcium hydroxide, mullite and quartz. The desulfurized fly ash contains limestone generated by the reaction of lime and carbon dioxide in the flue gas, desulfurized fly ash generated by the reaction of lime and sulfur oxide in the flue gas, and calcium hydroxide generated by the reaction of lime and moisture in the atmosphere in the storage process. In addition, quartz and mullite phases in the fly ash are also contained, and the non-unit cell phase of the fly ash is not seen due to the high crystalline phase in the desulfurized ash.
TABLE 3 chemical composition of desulfurized Ash (%)
The cement for preparing the aerated concrete adopts No. 42.5 ordinary portland cement, and the early strength agent adopts triethanolamine. The auxiliary additive contains pretreated carbon powder with the addition amount of 0.2-0.3% of the mass of the main material.
The following are preferred embodiments of the present invention given by the inventor, the present invention is not limited to these embodiments, and experiments by the applicant prove that the aerated concrete can be prepared within the scope given by the present invention.
Example 1
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in Table 4. Wherein aluminum powder, foam stabilizer and early strength agent are added externally.
TABLE 4 Properties of the ingredients and aerated concrete (Water to Material ratio 0.55)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized fly ash crushed in the step one into a ball mill for co-milling and mixing for 2 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, putting the mixture into a stirrer to stir and mix for 4min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer and an early strength agent, and continuing stirring for 50s to prepare casting slurry for later use;
step four, pouring the casting slurry prepared in the step three into a mold within 60s, placing the mold into a curing box at 55 ℃ for curing for 4h, and then demolding to prepare a module for later use;
step five, cutting the module prepared in the step four by a cutting machine according to a preset size to prepare a sample for later use;
and step six, putting the sample cut in the step five into a still kettle, and performing steam curing for 15 hours at 200 ℃ and 11MPa to obtain the finished product of the aerated concrete.
Example 2
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in a table 5. Wherein aluminum powder, foam stabilizer and early strength agent are added externally.
TABLE 5 Properties of the ingredients and aerated concrete (Water to Material ratio 0.60)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 2.5 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, placing the mixture into a stirrer to stir and mix for 7min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer and an early strength agent, and continuing stirring for 60s to prepare casting slurry for later use;
step four, pouring the casting slurry prepared in the step three into a mold within 60s, placing the mold into a curing box at the temperature of 60 ℃ for curing for 2h, and then demolding to prepare a module for later use;
step five, cutting the module prepared in the step four by a cutting machine according to a preset size to prepare a sample for later use;
and step six, putting the sample cut in the step five into a still kettle, and performing steam curing for 18 hours at 190 ℃ under 12MPa to obtain the finished product of the aerated concrete.
Example 3
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in a table 6. Wherein aluminum powder, foam stabilizer and early strength agent are added externally.
TABLE 6 Properties of the ingredients and aerated concrete (Water to Material ratio 0.55)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 1.5 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, putting the mixture into a stirrer to stir and mix for 5min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer and an early strength agent, and continuing stirring for 30s to prepare casting slurry for later use;
step four, pouring the casting slurry prepared in the step three into a mold within 60s, placing the mold into a curing box at 50 ℃ for curing for 3h, and then demolding to prepare a module for later use;
step five, cutting the module prepared in the step four by a cutting machine according to a preset size to prepare a sample for later use;
and step six, putting the sample cut in the step five into a still kettle, and performing steam curing for 12 hours at 210 ℃ under the pressure of 10MPa to obtain the finished product of the aerated concrete.
Example 4
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in Table 7. Wherein aluminum powder, foam stabilizer, early strength agent and pretreated carbon powder are added externally.
TABLE 7 Properties of the ingredients and aerated concrete (Water to Material ratio 0.55)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized fly ash crushed in the step one into a ball mill for co-milling and mixing for 2 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, a, taking activated carbon, and crushing the activated carbon into powder with the particle size of 30 microns for later use;
b. adding sodium carbonate into water to prepare a sodium carbonate solution with the mass concentration of 60g/L for later use;
c. immersing the activated carbon powder prepared in the step a into the sodium carbonate solution prepared in the step b, carrying out immersion type soaking treatment for 50min, taking out, placing in a drying oven at the temperature of 45 ℃ for drying treatment, fully drying to finish the pretreatment of the carbon powder, and carrying out vacuum storage for later use;
step four, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, placing the mixture into a stirrer to stir and mix for 7min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer, an early strength agent and the pretreated carbon powder prepared in the step three, and continuing stirring for 30s to prepare casting slurry for later use;
pouring the casting slurry prepared in the step four into a mold within 60s, placing the mold into a curing box at 55 ℃ for curing for 2h, and then demolding to prepare a module for later use;
step six, cutting the module prepared in the step five by a cutting machine according to a preset size to prepare a sample for later use;
and step seven, placing the sample cut in the step six into a microwave inductor, processing for 170 s under the power condition of 200W, then transferring the sample into a still kettle, and performing steam curing for 12h in the environment of 210 ℃ and 10MPa to obtain the finished product of aerated concrete.
Example 5
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in a table 8. Wherein aluminum powder, foam stabilizer, early strength agent and pretreated carbon powder are added externally.
TABLE 8 Properties of the ingredients and aerated concrete (Water to Material ratio 0.55)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 2.5 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, a, taking activated carbon, and crushing the activated carbon into powder with the particle size of 20 microns for later use;
b. adding sodium carbonate into water to prepare a sodium carbonate solution with the mass concentration of 50g/L for later use;
c. immersing the activated carbon powder prepared in the step a into the sodium carbonate solution prepared in the step b, carrying out immersion type immersion treatment for 30min, taking out, placing in a drying oven at the temperature of 55 ℃ for drying treatment, fully drying to finish the pretreatment of the carbon powder, and carrying out vacuum storage for later use;
step four, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, placing the slag, the mixed material and the power plant wastewater into a stirrer to stir and mix for 5min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer, an early strength agent and the pretreated carbon powder prepared in the step three, and continuing stirring for 30s to prepare casting slurry for later use;
pouring the casting slurry prepared in the step four into a mold within 60s, placing the mold into a curing box at 50 ℃ for curing for 4h, and then demolding to prepare a module for later use;
step six, cutting the module prepared in the step five by a cutting machine according to a preset size to prepare a sample for later use;
and step seven, placing the sample cut in the step six into a microwave inductor, processing for 180 s under the power condition of 250W, then transferring the sample into a still kettle, and performing steam curing for 12h in the environment of 210 ℃ and 10MPa to obtain the finished product of aerated concrete.
Example 6
The concrete ingredients of the regenerative aerated concrete with excellent frost resistance and the performance indexes of the obtained aerated concrete are shown in a table 9. Wherein aluminum powder, foam stabilizer, early strength agent and pretreated carbon powder are added externally.
TABLE 9 Properties of the ingredients and aerated concrete (Water to Material ratio 0.55)
The preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 1.5 hours, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90 percent for later use;
step three, a, taking activated carbon, and crushing the activated carbon into powder with the particle size of 25 microns for later use;
b. adding sodium carbonate into water to prepare a sodium carbonate solution with the mass concentration of 55g/L for later use;
c. immersing the activated carbon powder prepared in the step a into the sodium carbonate solution prepared in the step b, carrying out immersion type soaking treatment for 60min, taking out, placing in a drying oven at the temperature of 40 ℃ for drying treatment, fully drying to finish the pretreatment of the carbon powder, and carrying out vacuum storage for later use;
step four, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, placing the slag, the mixed material and the power plant wastewater into a stirrer to stir and mix for 5min, then adding auxiliary additives, namely aluminum powder, a foam stabilizer, an early strength agent and the pretreated carbon powder prepared in the step three, and continuing stirring for 30s to prepare casting slurry for later use;
pouring the casting slurry prepared in the step four into a mold within 60s, placing the mold into a curing box at 50 ℃ for curing for 3h, and then demolding to prepare a module for later use;
step six, cutting the module prepared in the step five by a cutting machine according to a preset size to prepare a sample for later use;
and step seven, putting the sample cut in the step six into a microwave inductor, processing for 120 s under the power condition of 300W, then transferring the sample into a still kettle, and performing steam curing for 12h in the environment of 210 ℃ and 10MPa to obtain the finished product of the aerated concrete.
Taking the aerated concrete sample prepared in the embodiment 5 of the invention as an example, the characterization of the X-ray diffraction pattern of the material before the co-grinding of the raw materials is shown in the attached figure 4, and the characterization of the X-ray diffraction pattern of the finished product after the preparation is shown in the attached figure 5. As can be seen from fig. 5: the mineral composition mainly comprises gypsum, calcite, ettringite, mullite and quartz. Photographs of the finished aerated concrete are shown in fig. 6 and 7.
The aerated concrete sample prepared in the embodiment 5 of the invention is inspected by the censorship Shanxi Jianke engineering technology, Inc., and the prepared aerated concrete sample meets the requirements of national standard dry density, strength and thermal conductivity coefficient. The microstructure photographs are shown in FIGS. 8 and 9. It can be seen from the figure that: the air hole walls of the aerated concrete are uniform, and the bonding between the bonding phase and the aggregate is tight, so that the aerated concrete is endowed with high strength.
The aerated concrete prepared in examples 1 to 6 of the present invention was tested for freezing resistance. In the test, the material is frozen at-15 to-30 ℃ and then melted in water at 20 ℃, which is called a freeze-thaw cycle. The freezing temperature should not be higher than-15 deg.c because water can freeze in the fine pores at a temperature lower than-15 deg.c. When the water is frozen, the volume is increased by about 9 percent, a pressure of about 100MPa is generated on the hole wall of the material, and cracks, peels and collapses from the surface to the inside under the repeated action of the pressure, so that the strength of the material is reduced and even the material is damaged. After the material is subjected to multiple freeze-thaw cycles, the frost resistance of the material can be judged. The following table shows the results of testing the aerated concrete prepared in examples 1 to 6 by Jianke engineering technologies, Inc. in Shaanxi province:
the table shows that the aerated concrete prepared by the invention has excellent freezing resistance and is suitable for being used in cold environment.
Claims (5)
1. The regenerative aerated concrete with excellent frost resistance comprises main materials, auxiliary additives and a dispersion medium, and is characterized in that the main materials comprise the following components in percentage by weight: 20-35% of fly ash, 20-35% of furnace slag, 10-20% of desulfurized ash and 10-25% of cement; the auxiliary additive comprises aluminum powder, a foam stabilizer, an early strength agent and pretreated carbon powder, and the addition amounts of the aluminum powder, the foam stabilizer and the early strength agent are respectively 0.1-0.2%, 0.45-0.55% and 0.45-0.60% of the mass of the main material; the dispersion medium is power plant wastewater, and the water-material ratio of the power plant wastewater to the main material and the auxiliary additive is 0.55-0.60;
the preparation process of the regenerative aerated concrete with excellent frost resistance comprises the following steps:
step one, drying the desulfurized fly ash, and then respectively crushing the slag and the dried desulfurized fly ash to the particle size of less than 1mm by using a crusher;
step two, according to the weight percentage, putting the fly ash, the cement and the desulfurized ash crushed in the step one into a ball mill for co-milling and mixing for 1.5-2.5 h, and then sieving through a 180-mesh sieve to prepare a mixed ingredient with the sieving amount of more than 90% for later use;
step three, according to the weight percentage, respectively taking the slag crushed in the step one, the mixed material prepared in the step two and the power plant wastewater, placing the mixture into a stirrer to stir and mix for 4-7 min, then adding auxiliary additives of aluminum powder, a foam stabilizer, an early strength agent and pretreated carbon powder, and continuing stirring for 30-60 s to prepare casting slurry for later use;
step four, pouring the casting slurry prepared in the step three into a mold, placing the mold into a curing box at the temperature of 50-60 ℃ for curing for 2-4 hours, and then demolding to prepare a module for later use;
step five, cutting the module prepared in the step four by a cutting machine according to a preset size to prepare a sample for later use;
putting the cut sample in the fifth step into a microwave inductor, processing for 120-180 s under the power condition of 200-300W, then transferring the sample into an autoclave, and performing steam curing for 12-18 h in the environment of 190-210 ℃ and 10-12 MPa to obtain the finished product aerated concrete;
the processing steps of the pretreated carbon powder are as follows:
a. taking activated carbon, and crushing the activated carbon into powder with the particle size of 20-30 microns for later use;
b. adding sodium carbonate into water to prepare a sodium carbonate solution with the mass concentration of 50-60 g/L for later use;
c. and (c) immersing the activated carbon powder prepared in the step (a) into the sodium carbonate solution prepared in the step (b), carrying out immersion type soaking treatment for 30-60 min, taking out, drying in a drying oven at the temperature of 40-50 ℃, fully drying to finish the pretreatment of the carbon powder, and storing in vacuum for later use.
2. The recycled aerated concrete with excellent frost resistance of claim 1, wherein: the mass concentration of sodium sulfate in the power plant wastewater is 5-6%.
3. The recycled aerated concrete with excellent frost resistance of claim 1, wherein: in the fourth step, the casting slurry stirred in the third step needs to be poured into the mold within 60 s.
4. The recycled aerated concrete with excellent frost resistance of claim 1, wherein: in the third step, the rotating speed of the stirrer is 2000-3000 r/min.
5. The recycled aerated concrete with excellent frost resistance of claim 1, wherein: the addition amount of the pretreated carbon powder is 0.2-0.3% of the mass of the main material.
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