CN111205061A - Preparation method of baking-free high-strength fly ash ceramsite - Google Patents
Preparation method of baking-free high-strength fly ash ceramsite Download PDFInfo
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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
- C04B28/24—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 containing alkyl, ammonium or metal silicates; containing silica sols
- C04B28/26—Silicates of the alkali metals
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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
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
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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 invention discloses a preparation method of a non-fired high-strength fly ash ceramsite, which comprises four stages of preparation of a mixed alkaline excitant, uniform mixing of the excitant and raw materials, balling by a balling disc and curing and forming; wherein the mixed alkaline excitant is prepared by mixing and crushing the dried desulfurized gypsum, the fly ash and the quicklime according to a certain proportion. The invention has the advantages of low cost, convenient preparation, simple process, light weight, high strength and the like, and can replace part of sandstone to prepare light aggregate concrete and produce prefabricated parts; the invention takes the fly ash as the main raw material, cement, quicklime and desulfurized gypsum as the mixed alkaline excitant and curing agent, and water glass as the binder, and the invention expands the comprehensive utilization path of the industrial solid waste fly ash and the industrial byproduct gypsum while preparing the non-fired high-strength fly ash ceramsite, and enhances the concept of green circular economy and sustainable development of building materials.
Description
Technical Field
The invention belongs to the field of ceramsite preparation, and particularly relates to a preparation method of a non-fired high-strength fly ash ceramsite.
Background
Ceramsite, a ceramic granule. The ceramsite is mainly round and oval spheres and also has irregular broken stone shapes, the inside of the ceramsite is of a porous honeycomb structure, the surface of the ceramsite is provided with a layer of hard shell, and the ceramsite is ceramic or enamel, has the functions of gas retention and water insulation and provides strength for the ceramsite. The ceramsite is mainly used in the field of building materials at the beginning of the invention, along with the development of the ceramsite and the continuous research of people on the ceramsite, the application field of the ceramsite is continuously expanded, and the ceramsite is mainly applied to the fields of buildings, landscaping, water treatment, diet sanitation, industrial filtration and the like at present.
The fly ash is also called fly ash, is solid waste obtained after coal-fired power generation of a thermal power plant, and is artificial volcanic ash with potential value. The fly ash under the macroscopic condition is usually grey white or grey black powder, the color deepens along with the increase of the content of incompletely burnt carbon in the fly ash, and the fly ash under the microscopic condition is represented as SiO under the action of high temperature and surface tension2、Al2O3、Fe2O3The molten spheres with smooth surfaces have different chemical component ratios of the fly ash due to the differences of factors such as coal sources, combustion modes, boiler types and the like, and can be generally divided into F grade and C grade if SiO is adopted2+Al2O3+Fe2O3If SiO, 70% is F grade2+Al2O3+Fe2O3More than 50% is C grade, and the sphere is also the main source of the activity of the fly ash.
At present, the domestic preparation technology of the high-strength fly ash ceramsite mainly takes sintering as main technology, and the research on the non-sintered high-strength fly ash ceramsite is less. For example, chinese patents CN201810518878.2, CN201410654069.6, and CN201610826984.8 disclose several methods for preparing fly ash ceramsite, but the preparation and molding of the ceramsite all require high-temperature sintering, consume a large amount of energy, and have complicated preparation techniques and equipment.
Chinese patent CN201711283767.X discloses a sintered fly ash ultra-light ceramsite and a preparation method thereof, 10-30% of bentonite is added as a raw material, the mass proportion of the fly ash is only 35-60%, and the fly ash needs to be sintered and molded under the high-temperature condition of 1150-1250 ℃, the mass proportion of the fly ash is lower, the necessary high-temperature condition is needed, and the cylinder pressure strength of the prepared ultra-light fly ash ceramsite is only 1.5-2.0 MPa.
Chinese patent CN201811309791.0 discloses a preparation method of light high-strength fly ash ceramsite, the bentonite mass ratio of the method reaches 40-55%, glass powder is used as an additive, and the bentonite is calcined and molded at a high temperature of 1200-1350 ℃, so that the comprehensive cost is high.
The baking-free fly ash ceramsite also has some problems.
Chinese patent CN201811191425.X discloses a preparation method of sintering-free fly ash ceramsite, which needs to form raw materials into porous slurry and then carry out spray granulation, the preparation method is complex, the ceramsite with the target particle size is not easy to obtain, the barrel pressure strength of the maintained and molded fly ash ceramsite is only 5.345MPa, sodium hydroxide with the mass fraction of 5-20% is used as an alkaline activator, and the sodium hydroxide is easy to react with carbon dioxide in the air to generate sodium carbonate, so that the fly ash loses the alkaline environment, the activity of glass beads is not easy to excite, and the later strength of the ceramsite is not increased.
The discharge amount of the fly ash is about 9 hundred million tons, a large amount of fly ash stacked for a long time not only occupies a large amount of land, but also can destroy the acid-base balance of the soil, raise dust is easily formed in windy weather, and great influence is caused to the natural environment and the living environment of human beings, in addition, the production process of the sintered fly ash ceramsite is complex, the flow is complicated, the manufacturing cost for consuming a large amount of heat energy is high, and the market price is about 300 yuan/m3The price of the fly ash ceramsite is far higher than that of sandstone, and the domestic non-fired fly ash ceramsite has low cylinder pressure strength and is not enough to be used as sandstone aggregate to be applied to the production of concrete, so that a preparation process of the non-fired fly ash ceramsite with low manufacturing cost, simple process, high cylinder pressure strength and excellent quality must be provided.
Disclosure of Invention
The invention provides a non-fired high-strength fly ash ceramsite, which aims to solve the problems of high manufacturing cost, higher market price, low strength and the like of the sintered fly ash ceramsite in the prior art, has the multiple advantages of low manufacturing cost, convenient preparation, simple process, light weight, high strength and the like, and can replace part of gravels to prepare light aggregate concrete and produce prefabricated parts. The invention takes the fly ash as the main raw material, cement, quicklime and desulfurized gypsum as the mixed alkaline excitant and curing agent, and water glass as the binder, and the invention expands the comprehensive utilization path of the industrial solid waste fly ash and the industrial byproduct gypsum while preparing the non-fired high-strength fly ash ceramsite, and enhances the concept of green circular economy and sustainable development of building materials.
The purpose of the invention can be realized by the following technical scheme:
the preparation method of the non-fired high-strength fly ash ceramsite comprises four stages of preparation of mixed alkaline excitant, uniform mixing of the excitant and raw materials, balling by a balling disc and curing and forming, and comprises the following detailed steps:
(1) preparing a mixed alkaline excitant: firstly, adding the dried desulfurized gypsum, the fly ash and the quicklime into a crusher according to a certain proportion, and then crushing for 5min at a high speed; under the action of high-speed pulverization, the fly ash SiO2、Al2O3、Fe2O3Further crushing the glass beads formed by melting, uniformly mixing the glass beads with the desulfurized gypsum and the quicklime, and taking out the uniformly mixed alkaline activator after the crusher is cooled;
(2) uniformly mixing an exciting agent and raw materials: sequentially putting the weighed fly ash, cement and mixed alkaline activator into a charging bucket, and stirring clockwise for 20min to ensure that all components are uniformly mixed;
(3) balling by a balling disc: weighing a part of the uniformly mixed raw materials, putting the weighed part of the uniformly mixed raw materials into a balling disc with a certain angle, spraying a sodium silicate aqueous solution containing a certain proportion on the mixture in a mist form along with the low-speed rotation of the balling disc, continuously adding the raw materials into the balling disc along with the formation of spheres, keeping the proportion of the spheres and the powder to be two to one in the whole process, continuously adding the sodium silicate aqueous solution, pouring the rest mixture into the balling disc after the spheres are mutually adhered, separating the spheres under the action of external force, forming a shell on the surface of the spheres, and finishing balling;
(4) curing and forming: screening the spheres, taking out the spheres with the target diameter of 5-10mm, curing for 24 hours under natural conditions to realize early hardening of the spheres, then putting the spheres into a constant temperature and humidity box for curing for 24 hours to excite the activity of the fly ash, finally putting the cured high-strength baking-free fly ash ceramsite into a 100 ℃ oven, drying for 4 hours to remove excessive water in the high-strength baking-free fly ash ceramsite, and finally taking the high-strength baking-free fly ash ceramsite out of the box to obtain the high-strength baking-free fly ash ceramsite.
The high-speed crushing in the step (1) is carried out under the high-speed mechanical rotation of 28000r/min of the blades of the crusher.
In the step (1), the fly ash is used for crushing the glass beads and dissolving SiO out as early as possible2、Al2O3So as to improve the activity of part of the fly ash; specifically, the fly ash is selected from secondary active fly ash produced by Gaodi environmental protection GmbH of Anhui province; the main chemical component of the fly ash is SiO2、Al2O3The mass fractions of CaO, CaO are respectively 50.5%, 30.4% and 4.52%, the residue on sieve is 12% -25%, and the activity index is 75-80.
In the step (1), the desulfurized gypsum is brown yellow powder containing a certain amount of free water in a natural state, and the desulfurized gypsum needs to be dried when preparing the mixed alkaline exciting agent, so that the strength of the ceramsite can be improved, and the digestion of lime can be inhibited; specifically, the desulfurized gypsum is selected from industrial byproducts generated after thermal power generation of a six-ampere power plant; the main component of the desulfurized gypsum is calcium sulfate dihydrate (chemical formula is CaSO)4·2H2O), the content of which is more than or equal to 93 percent, participates in hydration reaction with C3A、Ca(OH)2Hydrated calcium aluminum sulfate is generated by the reaction, thereby inhibiting the digestion of the quicklime.
In the step (1), the quicklime is white powder, and is further ground when preparing the mixed alkaline activator, aiming at generating Ca (OH) when meeting water2The condition required for providing the silicon-calcium reaction is not only an active excitant, but also a cementing materialThe main component of (a); specifically, the quicklime is selected from active quicklime produced by Pond state calcium, the effective calcium oxide content of the quicklime is 92.23%, the chemical name of the quicklime is calcium oxide (chemical formula CaO), and the quicklime can be mixed with water to generate Ca (OH)2Ca (OH) produced2Can be mixed with SiO in fly ash2、Al2O3The polymerization reaction occurs, and the final effect of the lime on the activation of the activity of the fly ash is Ca (OH)2The activation of the activity of the fly ash is to provide OH for breaking Si-O, Al-O bonds-While providing Ca needed for hydrating fly ash to form hydraulic cementing material2+。
In the step (1), the fly ash accounts for 10-15% of the total amount of the fly ash, the desulfurized gypsum accounts for 2-3% of all the raw materials, and the quicklime accounts for 3-5% of all the raw materials.
In the step (2), the cement is used for providing a calcium material, providing an alkaline environment and providing conditions required by a silicon-calcium reaction, and is also a strength provider of the unfired fly ash ceramsite; specifically, the cement is dark gray powder with certain fineness, has good plasticity and cohesiveness, and is derived from 425 ordinary portland cement produced by six-ampere sea snails; the cement belongs to a high-alkalinity material, and a large amount of Ca (OH) is separated out after the cement is hydrated2The glass micro-beads of the alkaline corrosion fly ash are utilized to dissociate more SiO2、Al2O3And reacts with the fly ash to improve the activity of the fly ash, and on the other hand, the cement can also be used as a binder and an early strength agent to help the balling of materials, thereby improving the mechanical property of the ceramsite.
In the step (2), the using amount of the cement is 10-15% of the total mass of the fly ash, the using amount of the fly ash is 90% of the total mass of the fly ash, and the total mass of the fly ash is 75-80% of all the raw materials.
The principle involved in the steps (1) and (2) is that firstly, quicklime in the mixed excitant reacts with water to quickly decompose and form Ca (OH)2And the cement is dissolved in water and undergoes hydration reaction when meeting water to further generate more Ca (OH)2Under such basic conditions, first with Ca (OH)2The reaction is carried out by mixing free SiO in the alkaline activator2、Al2O3The activity of the fly ash is excited to a certain degree, the fly ash vitreous body micro-beads are gradually dissolved under the alkaline condition along with the time, the interior of the vitreous body is further eroded after the constant-temperature and constant-humidity curing, the activity of the fly ash is further excited, and at the moment, SiO in the glass micro-beads2、Al2O3And Ca (OH)2The reaction is carried out to generate calcium silicate hydrate and aluminum silicate hydrate with gel property, thereby realizing the silicon calcium reaction, namely generating calcium silicate hydrate C-S-H gel which is the main reason for generating a certain strength of the ceramsite. The main several equations are as follows:
CaO+H2O→Ca(OH)2
mCaO·SiO2+nH2O→xCaO·SiO2·yH2O+(m-x)Ca(OH)2
(0.8～1.5)Ca(OH)2+SiO2+[n-(0.8～1.5)]H2O→(0.8～1.5)CaO·SiO2·nH2O]x(1.5～2.0)CaO·SiO2·nH2O+ySiO2→z(0.8～1.5)CaO·SiO2·nH2O
in the step (3), the revolution of the balling disc is 400r/min, the inclination angle is 32.5 degrees, the diameter is 40cm, the height of the side plate is 10cm, and the distance between the baffle and the balling disc is 5-10 cm.
In the step (3), the sodium silicate aqueous solution is used as an adhesive, so that the balling property and plasticity in the preparation process of the ceramsite are enhanced, meanwhile, the surface cracking of the ceramsite is prevented in the maintenance process of the ceramsite, and the mechanical property of the ceramsite is enhanced to a certain extent; specifically, the sodium silicate is white solid powder, the sodium silicate aqueous solution is an instant water glass solution with the mass concentration of 5%, the solution is prepared in a laboratory on site, and the solid sodium silicate is selected from industrial-grade special instant sodium silicate soda produced from Henan platinum-lubricated materials; the chemical formula of the instant soluble glass is Na2O·nSiO2·H2O can be quickly dissolved in water, the aqueous solution is alkaline, has strong adhesiveness and can be uniformly mixed with the powder materialMixing, on the other hand, water glass can also act as an activator in addition to acting as a binder, since the main component of water glass, Na2O·nSiO2·H2O, hydrolysis reaction in aqueous solution, and the reaction equation is as follows:
and the generated silicic acid sol SiO2Is unstable, wherein a part of Si-O bonds are easy to crosslink with each other to form a network polymer; under the alkaline condition, a small amount of silicic acid sol and fly ash glass beads react further, in a word, the addition of the water glass not only provides the bonding effect, but also matches the excitation effect of the quicklime and the gypsum, thereby better improving the excitation effect of the fly ash.
In the step (3), the ceramsite balling is divided into two processes, namely before and after the spheres are mutually adhered; specifically, in the stage before the spheres are mutually adhered, before the sphere forming disc is started, part of dry materials are put into the sphere forming disc, the prepared instant sodium silicate aqueous solution is sprayed in a mist form, after the surface of the powder is wetted, the sphere forming disc is opened, so that the initial materials and the aqueous solution are uniformly mixed, then the water glass solution is continuously sprayed in a mist form along with the rotation of the rotary disc, after the spheres are formed, the dry materials are added along with the spraying of the aqueous solution until the residual 1/4-1/5 of the dry materials are sprayed, and the water glass solution is continuously sprayed until the spheres are formed and mutually adhered; and in the stage after the spheres are adhered to each other, adding the rest dry materials to the formed spheres adhered to each other, scattering and basically forming the ceramsite, continuously spraying a water glass solution to moisten the surfaces of the spheres, continuously rotating the spheres into a sphere forming disc, continuously rolling the formed ceramsite, uniformly forming the shells of the spheres and compacting the shells of the spheres. And finally, stopping the balling disc, taking out the formed ceramsite, and screening to select the ceramsite with the target diameter of 5-10 mm.
The balling method can prepare the ceramsite with a core-shell structure, the shell forming material can be mixed dry material or common 425 Portland cement, the method ensures that the mechanical structure of the ceramsite is more stable, and simultaneously enhances the physical properties of the ceramsite.
In the step (4), the natural environment refers to outdoor temperature of 20-30 ℃, low temperature is not beneficial to improving the initial strength of the ceramsite, and too high temperature can cause surface cracking of the ceramsite and influence the appearance of the ceramsite.
In the step (4), the natural environment is maintained for 24 hours, so that the strength of the ceramsite is pre-improved, and the ceramsite shell is hardened, so that the ceramsite shell has the strength condition capable of being maintained in a constant temperature and humidity chamber and the core body is protected from being damaged; specifically, the strength of the pre-enhanced ceramsite is mainly obtained by the silicon-calcium reaction of the hardened and pre-activated fly ash of cement; the ordinary silicate cement clinker is mainly made of tricalcium silicate (3 CaO. SiO)2) Dicalcium silicate (β -2 CaO. SiO)2) Tricalcium aluminate (3 CaO. Al)2O3) And tetracalcium aluminoferrite (4 CaO. Al)2O3·Fe2O3) Four minerals, their relative contents being approximately: 37-60% of tricalcium silicate, 15-37% of dicalcium silicate, 7-15% of tricalcium aluminate and 10-18% of tetracalcium aluminoferrite, wherein the four minerals can perform hydration reaction after meeting water, but due to the difference of the mineral structures and the difference of the properties of corresponding hydration products, the hydration rate and strength of each mineral are greatly different, and the minerals can be arranged according to the hydration rate: tricalcium aluminate>Tetra calcium aluminoferrite>Tricalcium silicate>Dicalcium silicate, which can be arranged in terms of final strength: dicalcium silicate>Tricalcium silicate>Tetra calcium aluminoferrite>Tricalcium aluminate, and the setting time, early strength of cement, is largely dependent on tricalcium aluminate and tricalcium silicate.
Setting and hardening of cement:
the hydration reaction principle of the tricalcium aluminate is as follows:
3CaO·Al2O3+6H2O→3CaO·Al2O3·6H2O
the hydration reaction principle of tricalcium silicate is as follows:
3CaO·SiO2+H2O→CaO·SiO2·YH2o (gel) + Ca (OH)2；
The hydration reaction of the tetracalcium aluminoferrite is similar to that of tricalcium aluminate, and the reaction principle is as follows:
4CaO·Al2O3·Fe2O3+7H2O→3CaO·Al2O3·6H2O+CaO·Fe2O3·H2O
the hydration reaction of dicalcium silicate is similar to tricalcium silicate, and the reaction principle is as follows:
2CaO·SiO2+H2O→CaO·SiO2·YH2o (gel) + Ca (OH)2；
The reaction principle of calcium and silicon has been described and will not be described in detail.
In the step (4), the constant temperature and humidity box is a steam curing box capable of keeping stable temperature and humidity, and can realize full-automatic temperature and humidity control, so that the aim of exciting a silicon-calcium reaction is fulfilled, and the ceramsite has excellent physical properties; specifically, the temperature and humidity of a HWS-300X constant temperature and humidity box produced by Suzhou Donghua test instruments Co., Ltd are respectively set to be 80 ℃ and 100 ℃ and 90%, wherein the temperature rising speed is strictly controlled, the rapid dehydration on the surface of the ceramsite can cause cracking and influence the physical property and the appearance of the ceramsite, the too slow temperature rising and the too fast humidity rising can cause the strength of the ceramsite to be slowly improved, the surface still has an unhardened shell which is dissolved in water and can also influence the mechanical property of the ceramsite, the preparation process of the high-strength baking-free ceramsite described by the invention has the advantages that the constant temperature and humidity maintenance of the ceramsite is divided into three processes, the temperature and the humidity gradually rise in the first stage for 8 hours, even if the ceramsite gradually undergoes a silicon-calcium reaction under the condition of proper temperature rising, the strength is gradually improved, and meanwhile, the proper humidity condition is adopted, the ceramsite is not dissolved, the mechanical property and the appearance of the ceramsite are ensured, and the stage is a basic stage; in the second stage, the temperature and the humidity are kept stable for 8 to 16 hours, so that the inside of the ceramsite is further subjected to a silicon-calcium reaction, and the strength of the ceramsite is stable; and in the third stage, taking out the ceramsite for 16-24 h, and washing with water, wherein the purpose of the process is to enable the surface of the ceramsite to be glazed, prepare for next steaming, putting the washed ceramsite into a constant-temperature constant-humidity box, increasing the temperature to 100 ℃, and keeping the humidity unchanged, so as to further stimulate the activity of the fly ash glass microspheres and promote further silicon-calcium reaction, so that the strength of the ceramsite is improved again, and the purpose of washing with water is to ensure that the surface of the ceramsite is cracked after the temperature is improved again. And finally, placing the cured and formed ceramsite into an oven, drying for 4 hours at 100 ℃, removing the water in the ceramsite, and finishing the preparation of the ceramsite.
The invention has the beneficial effects that:
1. the invention mainly takes the second-level fly ash as the main raw material, the mixing amount of the fly ash reaches 75-80%, the proportion of the fly ash in the non-sintered ceramsite is greatly improved, the preparation cost of the ceramsite is reduced, a new utilization way of the fly ash is added, and the significance of green circular economy is enhanced.
2. The invention provides a new process for pre-activation, which is characterized in that part of fly ash, quicklime and desulfurized gypsum are further mixed and ground to prepare a mixed alkaline activator with low activity, thereby greatly reducing the process flow time for preparing ceramsite.
3. The invention adopts quicklime and ordinary 425 silicate cement as alkaline excitant, provides ion raw materials required by calcium-silicon reaction, creates alkaline environment for calcium-silicon reaction, and simultaneously the hydraulicity of the cement ensures the early strength of the ceramsite, enhances the plasticity of the materials and simplifies the molding of the ceramsite.
4. The method adopts the industrial byproduct generated after thermal power generation of the power plant as the curing agent, simultaneously inhibits quick digestion of the quicklime, provides a stable silicon-calcium reaction environment for the ceramsite, and widens the combined utilization of the industrial byproduct and the industrial solid waste.
5. The invention adopts the instant sodium silicate solution as the adhesive and the cement to act together, so that the physical structure of the ceramsite is more stable, the ceramsite has firmer shell, and meanwhile, the ceramsite has stronger balling property in the preparation process, so that the adhesiveness among the powder is stronger, and the cracking phenomenon of the ceramsite is reduced.
6. The invention uses the balling disc as a balling tool, and creatively combines a cladding method in the process of balling the ceramsite, thereby protecting the ceramsite core and providing a prior condition for maintenance of the ceramsite, and the shell is not limited to one material.
7. The invention improves the maintenance method of the ceramsite, refines the maintenance process of the ceramsite, and excites the activity of the fly ash microbeads to the maximum extent, so that the silicon-calcium reaction is thorough, and the physical properties and the appearance of the ceramsite after balling are ensured.
8. The cylinder compressive strength of the prepared unburned fly ash ceramsite is more than 10MPa and is far higher than that of other unburned fly ash in China at present, the prepared fly ash ceramsite with the thickness of 2-5mm can replace traditional river sand to serve as fine aggregate, the fly ash ceramsite with the thickness of 5-10mm can replace traditional stone to serve as coarse aggregate, and a light high-strength green concrete prefabricated component is developed, so that the comprehensive utilization rate of the fly ash and derivatives thereof in the concrete prefabricated component is further improved.
Detailed Description
The technical solutions of the present invention are described below clearly and completely by using specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A preparation method of high-strength baking-free fly ash ceramsite comprises the following raw materials in parts by mass:
2190 parts of secondary fly ash, 90 parts of quick lime, 60 parts of desulfurized gypsum, 390 parts of common 425 Portland cement and 55 parts of instant sodium silicate;
a preparation method of high-strength baking-free fly ash ceramsite comprises the following preparation steps:
1. firstly weighing 219 parts of fly ash and 60 parts of gypsum which are 10 percent of the total using amount of the fly ash, placing the fly ash and the gypsum into a drying oven for quick drying, then placing 90 parts of weighed quicklime and prepared fly ash and gypsum into a high-speed pulverizer, and pulverizing for 5 min;
2. weighing 1971 parts of fly ash and 390 parts of ordinary 425 portland cement, and putting the fly ash and the ordinary 425 portland cement into a containing bucket;
3. uniformly mixing the prepared mixed alkaline exciting agent and the prepared raw materials, and dividing the mixture into two parts, namely 2550 parts of one part and 180 parts of the other part;
4. weighing 55 parts of instant sodium silicate which is solid sodium silicate accounting for 2 mass percent of all raw materials, and preparing 5 percent sodium silicate aqueous solution (additive);
5. and (4) balling by a balling disc, uniformly scattering the remaining 180 parts of dry materials on the ball after the ball is adhered, and screening the ball with the diameter of 5-10mm after balling is finished. Sieving spheres of 5-10 mm;
6. and (5) finishing maintenance, drying and discharging.
Example 2
A preparation method of high-strength baking-free fly ash ceramsite comprises the following raw materials in parts by mass:
2190 parts of secondary fly ash, 90 parts of quick lime, 60 parts of desulfurized gypsum, 390 parts of ordinary 425 portland cement, two parts, one part of 210 parts, one part of 180 parts and 55 parts of instant sodium silicate;
a preparation method of high-strength baking-free fly ash ceramsite comprises the following preparation steps:
1. firstly weighing 219 parts of fly ash and 60 parts of gypsum which are 10 percent of the total using amount of the fly ash, placing the fly ash and the gypsum into a drying oven for quick drying, then placing 90 parts of weighed quicklime and prepared fly ash and gypsum into a high-speed pulverizer, and pulverizing for 5 min;
2. weighing 1971 parts of fly ash and 210 parts of ordinary 425 portland cement, and putting the fly ash and the ordinary 425 portland cement into a containing barrel;
3. uniformly mixing the prepared mixed alkaline excitant and the prepared raw materials;
4. weighing 55 parts of instant sodium silicate which is solid sodium silicate accounting for 2 mass percent of all raw materials, and preparing 5 percent sodium silicate aqueous solution (additive);
5. balling by a balling disc, uniformly scattering the rest 180 parts of common 425 portland cement on the ball after the ball is adhered, and screening the ball with the diameter of 5-10mm after balling is finished;
6. and (5) finishing maintenance, drying and discharging.
Example 3
A preparation method of high-strength baking-free fly ash ceramsite comprises the following raw materials in parts by mass:
2400 parts of secondary fly ash, 90 parts of quick lime, 60 parts of desulfurized gypsum, 450 parts of ordinary 425 portland cement, namely, two parts of 255 parts of one part, 195 parts of one part and 60 parts of instant sodium silicate;
a preparation method of high-strength baking-free fly ash ceramsite comprises the following steps:
1. firstly, weighing 240 parts of fly ash and 60 parts of gypsum which are 10 percent of the total using amount of the fly ash, putting the fly ash and the gypsum into a drying oven for quick drying, then putting 90 parts of weighed quicklime and prepared fly ash and gypsum into a high-speed pulverizer, and pulverizing for 5 min;
2. 2160 parts of fly ash and 255 parts of ordinary 425 silicate cement are weighed and put into a containing barrel;
3. uniformly mixing the prepared mixed alkaline excitant and the prepared raw materials;
4. weighing solid sodium silicate accounting for 2% of the mass fraction of all raw materials, namely 60 parts of instant sodium silicate, and preparing 5% of sodium silicate aqueous solution (additive);
5. balling by a balling disc, uniformly scattering the rest 195 parts of common 425 portland cement on the ball after the ball is adhered, and screening the ball with the diameter of 5-10mm after balling is finished;
6. and (5) finishing maintenance, drying and discharging.
Comparative example
Qihong haydite-sintered haydite in Shanxi jin.
For the high-strength unfired fly ash ceramsite prepared in the above examples 1-3 and comparative example, according to the second part of the lightweight aggregate and the test method thereof: testing method of lightweight aggregate (GB/T17431.2-2010) and measuring the cylinder pressure strength, the bulk density and the water absorption rate for 1 hour. The test results are given in the following table:
| barrel pressure intensity (MPa) | Bulk Density (kg/m)3) | Water absorption after 1 hour% | |
| Example 1 | 10.23 | 830 | 13.6 |
| Example 2 | 10.98 | 835 | 12.1 |
| Example 3 | 11.12 | 850 | 11.5 |
| Comparative example | 6.4 | 830 | 10 |
As can be seen from the data in the table, the cylinder pressure strength of the ceramsite prepared in the examples 1-3 is 10.23-11.12MPa, and the bulk density is 830-3The water absorption rate of 1 hour is 11.5-13.6%, compared with the comparative example, the tube pressure strength of the ceramsite prepared by the method is more than 10MPa, which is far higher than that of the ceramsite prepared by the prior artThe barrel compression strength of other domestic unfired fly ash can be maintained in the bulk density and 1h water absorption rate, and the application value is high.
The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the invention as defined in the accompanying claims.
Claims (9)
1. The preparation method of the non-fired high-strength fly ash ceramsite is characterized by comprising four stages of preparation of mixed alkaline excitant, uniform mixing of the excitant and raw materials, balling by a balling disc and curing and forming, and comprises the following detailed steps:
(1) preparing a mixed alkaline excitant: firstly, adding the dried desulfurized gypsum, the fly ash and the quicklime into a crusher according to a certain proportion, crushing at a high speed for 5min, and discharging after the crusher is cooled to obtain a mixed alkaline activator;
(2) uniformly mixing an exciting agent and raw materials: sequentially putting the weighed fly ash, cement and mixed alkaline activator into a holding barrel, and stirring clockwise for 20 min;
(3) balling by a balling disc: weighing a part of the raw materials uniformly mixed in the step (2) and putting the weighed part into a balling disc with a certain angle, spraying a sodium silicate aqueous solution on the mixture along with the low-speed rotation of the balling disc, continuously adding the raw materials into the balling disc along with the formation of spheres, keeping the proportion of the spheres and the powder to be two to one in the whole process, continuously adding the sodium silicate aqueous solution, pouring the rest mixture into the balling disc after the spheres are mutually adhered, separating the spheres under the action of external force and forming a shell on the surface of the spheres, and finishing balling;
(4) curing and forming: screening the spheres, taking out the spheres with the target diameter of 5-10mm, curing for 24h under natural conditions, then putting the spheres into a constant temperature and humidity box for curing for 24h, finally putting the cured high-strength baking-free fly ash ceramsite into a 100 ℃ oven, drying for 4h, and finally taking out the baked fly ash ceramsite out of the box to obtain the high-strength baking-free fly ash ceramsite.
2. The method for preparing unburned high-strength fly ash ceramsite according to claim 1, wherein the high-speed pulverization in the step (1) is carried out by mechanically rotating the blades of the pulverizer at a high speed of 28000 r/min.
3. The method for preparing baking-free high-strength fly ash ceramsite according to claim 1, wherein the main chemical component of the fly ash in the step (1) is SiO2、Al2O350.5 percent of CaO, 30.4 percent of CaO and 4.52 percent of CaO by mass, 12 to 25 percent of screen residue and 75 to 80 percent of activity index; the main component of the desulfurized gypsum is calcium sulfate dihydrate, the content of which is more than or equal to 93 percent, participates in hydration reaction and reacts with C3A、Ca(OH)2Hydrated calcium aluminum sulfate is generated by reaction, and the digestion of quicklime is inhibited; the effective calcium oxide content of the quicklime is 92.23%.
4. The method for preparing the unfired high-strength fly ash ceramsite according to claim 1, wherein the fly ash in the step (1) accounts for 10-15% of the total amount of the fly ash, the desulfurized gypsum accounts for 2-3% of all raw materials, and the quicklime accounts for 3-5% of all raw materials.
5. The method for preparing baking-free high-strength fly ash ceramsite according to claim 1, wherein the amount of the cement in the step (2) is 10-15% of the total mass of the fly ash, the amount of the fly ash is 90% of the total mass of the fly ash, and the total mass of the fly ash is 75-80% of all raw materials.
6. The method for preparing the unfired high-strength fly ash ceramsite according to claim 1, wherein the rotation number of the balling disk in the step (3) is 400r/min, the inclination angle is 32.5 degrees, the diameter is 40cm, the height of the side plate is 10cm, and the distance between the baffle and the balling disk is 5-10 cm.
7. The method for preparing baking-free high-strength fly ash ceramsite according to claim 1,characterized in that the sodium silicate aqueous solution in the step (3) is an instant water glass solution with the mass concentration of 5 percent, and the chemical formula of the instant water glass is Na2O·nSiO2·H2O。
8. The method for preparing the unfired high-strength fly ash ceramsite according to claim 1, wherein the step (3) of pelletizing the ceramsite is carried out in two steps, namely before and after the spheres are adhered to each other; in the stage before the spheres are mutually adhered, before the sphere forming disc is started, partial dry materials are put into the sphere forming disc, the prepared instant sodium silicate aqueous solution is sprayed in a mist form, after the surface of the powder is wetted, the sphere forming disc is opened, the initial materials and the aqueous solution are uniformly mixed, then the water glass solution is continuously sprayed in a mist form along with the rotation of the rotary disc, after the spheres are formed, the dry materials are added along with the spraying of the aqueous solution until the dry materials of 1/4-1/5 remain, and the water glass solution is continuously sprayed until the spheres are formed and are mutually adhered; and in the stage after the spheres are mutually adhered, waiting for the mutual adhesion of the spheres, adding the residual dry materials to the formed and mutually adhered spheres, scattering the ceramsite and basically forming, continuously spraying a water glass solution to moisten the surfaces of the spheres, continuously rotating a balling disc to enable the formed ceramsite to continuously roll, so that the shell of the formed ceramsite is uniformly formed, the inside of the formed ceramsite is more compact, finally stopping the balling disc, taking out the formed ceramsite, and screening to obtain the ceramsite with the target diameter of 5-10 mm.
9. The method for preparing baking-free high-strength fly ash ceramsite according to claim 1, wherein the natural environment in the step (4) is 20-30 ℃ of outdoor temperature.
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