CN114014620B - Lightweight aggregate and preparation method and application thereof - Google Patents
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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
- C04B28/14—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 calcium sulfate cements
- C04B28/142—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 calcium sulfate cements containing synthetic or waste calcium sulfate cements
- C04B28/144—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 calcium sulfate cements containing synthetic or waste calcium sulfate cements the synthetic calcium sulfate being a flue gas desulfurization product
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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
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/02—Agglomerated materials, e.g. artificial aggregates
- C04B18/021—Agglomerated materials, e.g. artificial aggregates agglomerated by a mineral binder, e.g. cement
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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
- C04B28/006—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 mineral polymers, e.g. geopolymers of the Davidovits type
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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
- C04B2111/00017—Aspects relating to the protection of the environment
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
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Abstract
The invention provides a lightweight aggregate and a preparation method and application thereof. The lightweight aggregate is prepared by powder under a balling process, the powder contains alpha-type semi-hydrated gypsum, the microscopic appearance of the alpha-type semi-hydrated gypsum is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-300 accounts for more than 95 percent of the total alpha-type semi-hydrated gypsum. The lightweight aggregate provided by the invention has the advantages of low density, high porosity, high softening coefficient, high strength, excellent water resistance and good chemical compatibility with geopolymer concrete, and provides a new shortcut for resource utilization of waste gypsum in the field of buildings and saving of natural sandstone resources.
Description
Technical Field
The invention belongs to the technical field of material science and engineering, and particularly relates to a lightweight aggregate and a preparation method and application thereof.
Background
The byproducts of the industrial production, namely the desulfurized gypsum, the phosphogypsum and the titanium gypsum, are respectively derived from the flue gas desulfurization of a coal-fired power plant, the fertilizer production and the titanium dioxide production. As solid waste, the waste gypsum accumulated in large quantities not only occupies valuable land resources, but also causes pollution to soil, water and atmosphere to different degrees. Taking desulfurized gypsum as an example, the annual output of desulfurized gypsum in China is more than 7000 million tons, and the comprehensive utilization rate of desulfurized gypsum is about 70 percent and far lower than that of desulfurized gypsum in China (more than 90 percent), so that a large amount of desulfurized gypsum is stockpiled in China. Compared with the desulfurized gypsum, the phosphogypsum and titanium gypsum have more impurities, larger comprehensive reserves and higher recycling difficulty. Therefore, the development of an application technology with good compatibility aiming at waste gypsum is urgent.
At present, waste gypsum is mainly used for producing building gypsum powder, gypsum products, cement retarders, soil conditioners and the like, but the application of the waste gypsum in bulk materials such as buildings is very limited due to the problems of high impurity content, poor water resistance, low strength and the like of the waste gypsum.
Disclosure of Invention
The lightweight aggregate has low density, high porosity, high softening coefficient, high strength and excellent water resistance, has great significance for improving the comprehensive utilization rate and additional value of waste gypsum such as desulfurized gypsum and the like, and has great application potential in the field of producing geopolymer concrete non-structural members.
Specifically, the invention provides the following technical scheme:
the lightweight aggregate is prepared from powder by a balling process, wherein the powder comprises alpha-type semi-hydrated gypsum, the microscopic morphology of the alpha-type semi-hydrated gypsum is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-300 accounts for more than 95% of the total alpha-type semi-hydrated gypsum.
The percentage is a ratio of 100% to the total number of α -hemihydrate gypsum that can be observed by a scanning electron microscope at about 500 times.
The length-diameter ratio of the alpha-type semi-hydrated gypsum prepared in the prior art is generally in the range of 1.4-2. The inventor finds that the alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-300 can form a cross-network structure in the lightweight aggregate, so that a large amount of pores are provided for the lightweight aggregate, and therefore more water is required for curing in a wet environment to reach the standard consistency. After the maintenance is finished, a large amount of alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-300 is dispersed in the lightweight aggregate, redundant water is stored in the lightweight aggregate, pores are left after the lightweight aggregate is dried to reduce the volume density of the lightweight aggregate, and meanwhile, the lightweight aggregate can play a role in internal maintenance for auxiliary materials, so that the strength of the lightweight aggregate is ensured.
In a preferred embodiment, the alpha hemihydrate gypsum having an aspect ratio of 100 to 150 accounts for 95% or more of the total alpha hemihydrate gypsum. The light aggregate dispersed with a large amount of alpha-type semi-hydrated gypsum with the length-diameter ratio of 100 to 150 can greatly reduce the volume density on the basis of high strength.
In a preferred embodiment, the powder material contains 60 to 90 percent of alpha-hemihydrate gypsum by weight percentage.
In a preferred embodiment, the preparation method of the alpha-hemihydrate gypsum comprises the following steps:
mixing gypsum with water, and keeping the temperature of the obtained mixture for 1-4 h under the pressure of 0.198-0.882 MPa, the temperature of 120-180 ℃ and the stirring speed of 200-500 r/min;
further preferably, the gypsum is one or more selected from desulfurized gypsum, phosphogypsum and titanium gypsum.
In a preferred embodiment, the mass ratio of gypsum to water is 1.
In a preferred embodiment, the powder lot further comprises an auxiliary material selected from at least one of cement, fly ash and lime, further preferably, the auxiliary material is a mixture of cement, fly ash and lime, and more preferably, the mass ratio of the cement, fly ash and lime is 40-60: 20 to 40:0 to 20.
In a preferred embodiment, the powder comprises 10 to 40% by weight of the auxiliary material.
In a preferred embodiment, the lightweight aggregate has a particle size of 8mm to 15mm.
The invention also provides a preparation method of the lightweight aggregate, which comprises the following steps:
preparing the powder into a spheroid material, and maintaining the spheroid material in a wet environment;
further preferably, the humid environment is an environment with humidity greater than 80%, and the curing time is 12-36 h.
In a preferred embodiment, the material for preparing the powder material into the spheroid is specifically:
adding the powder into a disc granulator, and spraying a binding agent during rolling granulation to obtain the powder;
wherein the binding agent is an aqueous solution of a retarder and a water repellent;
further preferably, the mass of the retarder in the binding agent is 1-2% of the mass of the solvent water, and the mass of the water repellent is 5-6.5% of the mass of the solvent water;
and/or the retarder is selected from one or more of sodium tartrate, sodium citrate and sodium acetate;
and/or the water repellent is selected from one or more than two of ammonium borate, sodium methylsiliconate and dimethyl polysiloxane.
The invention also protects the application of the lightweight aggregate or the lightweight aggregate prepared by the preparation method in geopolymer concrete.
The invention has the following beneficial effects:
the lightweight aggregate provided by the invention has the advantages of low density, high porosity, high softening coefficient, high strength and excellent water resistance, can be prepared by efficiently utilizing the waste gypsum with lower utilization rate at present, can effectively relieve the harm of the waste gypsum to the environment, is low in production cost, is environment-friendly in the production process, and does not generate hazardous waste.
When the lightweight aggregate is applied to geopolymer concrete, the wettability and compatibility of the lightweight aggregate and geopolymer are good, sulfate ions contained on the surface of the lightweight aggregate can promote the hydration reaction of geopolymer, so that the interface structure of geopolymer-gypsum aggregate is compact, and the interface strength is improved.
Drawings
FIG. 1 is an SEM image of a fibrous alpha hemihydrate gypsum powder prepared in example 1.
FIG. 2 shows the spheroid material prepared in example 1.
Fig. 3 is an SEM image of the lightweight aggregate prepared in example 1.
FIG. 4 is an SEM image of the fibrous alpha hemihydrate gypsum powder prepared in example 2.
Fig. 5 is an SEM image of the gypsum powder prepared in comparative example 1.
Detailed Description
The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications.
In the following examples, the equipment and the like used are not shown to manufacturers, and are all conventional products available from regular vendors. The process is conventional unless otherwise specified, and the starting materials used are commercially available from published sources.
Example 1
Example 1 provides a lightweight aggregate prepared by the steps of:
(1) Firstly, adding water and desulfurized gypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 45 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder, wherein the micro-morphology is fibrous, and alpha-type semi-hydrated gypsum with the length-diameter ratio of 100-150 accounts for more than 95% of all alpha-type semi-hydrated gypsum through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder with auxiliary materials (60 parts of 10-80 mu m cement and 40 parts of 20-61 mu m fly ash) by adopting a ball milling method according to a ratio of 2 to 1 to prepare a mixture, and simultaneously adding 2 percent of sodium acetate and 6 percent of sodium methyl silanol into an aqueous solution to prepare a mixed solution;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding a mixed solution with the mass of 20% of the mixture as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 10-15 mm;
(5) Will be sphericalThe material was cured at a humidity of 90% for 24 hours to obtain a lightweight aggregate. The detection shows that the aggregate cylinder has the compression density of 14.1MPa and the bulk density of 590g/cm 3 The water absorption was 4.1%. After 15 wet and dry cycles, the strength loss was 6.7%.
FIG. 1 is an SEM image of the alpha hemihydrate gypsum powder prepared in example 1.
FIG. 2 shows the spheroid material prepared in example 1.
FIG. 3 is an SEM photograph of a lightweight aggregate prepared in example 1.
Example 2
Example 2 provides a lightweight aggregate prepared by the steps of:
(1) Adding water and phosphogypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 50 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder which is white in appearance, has the purity of more than 97 percent, is fibrous in microscopic appearance, and accounts for more than 95 percent of all alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-100 through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder and auxiliary materials (60 parts of 10-80 mu m cement, 20 parts of 20-61 mu m fly ash and 20 parts of 20-61 mu m lime) according to a ratio of 3 to 2 by adopting a ball milling method to prepare a mixture, and simultaneously adding 1% of sodium tartrate and 6.5% of sodium methyl silanol into an aqueous solution to prepare a mixed solution;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding a mixed solution with the mass of 25% of the mixture as a binding agent in the rotation process to form balls, and obtaining a spheroid material with the particle size of 8-10 mm;
(5) The spheroid material was cured at 80% humidity for 12 hours to obtain a lightweight aggregate. The detection proves that the compressive strength of the aggregate cylinder is 17.9MPa, and the bulk density is 927g/cm 3 The water absorption was 3.1%. After 15 wet and dry cycles, the strength was lost 5%.
FIG. 4 is an SEM image of the fibrous alpha hemihydrate gypsum powder prepared in example 2.
Example 3
Example 3 provides a lightweight aggregate prepared by the steps of:
(1) Adding water and titanium gypsum into a reaction kettle according to a ratio of 4;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 40 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder, wherein the micro-morphology is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 200-300 accounts for more than 95 percent of all alpha-type semi-hydrated gypsum through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder and auxiliary materials (40 parts of 10-80 mu m cement, 40 parts of 20-61 mu m fly ash and 20 parts of 20-61 mu m lime) according to a proportion of 9 to 1 by adopting a ball milling method to prepare a mixture, and simultaneously adding 2 percent of sodium citrate and 5 percent of sodium methyl siliconate into an aqueous solution to prepare a mixed solution;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding a mixed solution with the mass of 15% of that of the mixture as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 12-15 mm;
(5) The spheroid material was cured at 100% humidity for 36 hours to obtain lightweight aggregate. The detection proves that the aggregate cylinder compressive strength is 10.5MPa, and the bulk density is 309g/cm 3 The water absorption was 6.2%. After 15 dry and wet cycles, the strength lost 9.6%.
Comparative example 1
Comparative example 1 provides a composite gypsum aggregate prepared by the steps of:
(1) Firstly, adding water and desulfurized gypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 45 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder with the length-diameter ratio of less than 10;
(3) Uniformly mixing alpha-type semi-hydrated gypsum powder and auxiliary materials (60 parts of 10-80 mu m cement and 40 parts of 20-61 mu m fly ash) according to a proportion of 2 to 1 by adopting a ball milling method to prepare a mixture, and simultaneously adding 2 percent of sodium acetate and 6 percent of sodium methyl silanol into an aqueous solution to prepare a mixed solution;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding a mixed solution with the mass of 20% of the mixture as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 10-15 mm;
(5) The spheroid material was cured at a humidity of 90% for 24 hours to obtain a lightweight aggregate. The detection shows that the aggregate cylinder has the compression density of 17.1MPa and the bulk density of 1200g/cm 3 The water absorption was 2.9%. After 15 dry and wet cycles, the strength lost 4.2%.
Fig. 5 is an SEM image of the gypsum powder prepared in comparative example 1.
The results of the comparative example 1 and the comparative example 1 show that the cylindrical compressive strength of the example 1 is only reduced by 17.5% compared with that of the comparative example 1 on the basis of meeting the standard cylindrical compressive strength requirement of more than or equal to 5MPa (according to the national standard GB/T17431 lightweight aggregate and experimental method thereof), but the volume density is effectively reduced by 50.8%, and the optimization effect is obvious.
Comparative example 2
Comparative example 2 provides a gypsum aggregate prepared by the steps of:
(1) Firstly, adding water and desulfurized gypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 45 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder, wherein the micro-morphology is fibrous, and alpha-type semi-hydrated gypsum with the length-diameter ratio of 100-150 accounts for more than 95% of all alpha-type semi-hydrated gypsum through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder and auxiliary materials (40 parts of 20-61 mu m coal gangue, 20 parts of 20-61 mu m iron tailings and 20 parts of 20-61 mu m steel slag) according to a ratio of 2 to 1 by adopting a ball milling method to prepare a mixture, and simultaneously adding 2 percent of sodium acetate and 6 percent of sodium methyl silanol into an aqueous solution to prepare a mixed solution;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding 20% of mixed solution as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 10-15 mm;
(5) The spheroid material was cured at a humidity of 90% for 24 hours to obtain a lightweight aggregate. The detection shows that the aggregate cylinder has the compression density of 2MPa and the volume density of 734g/cm 3 The water absorption was 3.8%. After 15 dry and wet cycles, there was no strength.
Comparative example 3
Comparative example 3 provides a gypsum aggregate prepared by the steps of:
(1) Firstly, adding water and desulfurized gypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 45 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder, wherein the micro-morphology is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 100-150 accounts for more than 95 percent of the total alpha-type semi-hydrated gypsum through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder and auxiliary materials (40 parts of 10-80 mu m cement, 20 parts of 20-61 mu m fly ash and 20 parts of 20-61 mu m coal gangue) according to a proportion of 2;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding 20% of mixed solution as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 10-15 mm;
(5) The spheroid material was cured at a humidity of 90% for 24 hours to obtain a lightweight aggregate. The aggregate cylinder has the compression density of 5.6MPa and the bulk density of 633g/cm through detection 3 The water absorption was 3.4%. Strength after 15 dry and wet cycles<3.5MPa。
Comparative example 4
Comparative example 4 provides a gypsum aggregate prepared as follows:
(1) Firstly, adding water and desulfurized gypsum into a reaction kettle according to the proportion of 5;
(2) Draining water completely by utilizing the pressure in the kettle, taking out a prepared sample, further removing redundant free water by using a vacuum suction filter, and finally drying at 45 ℃ to constant weight to obtain alpha-type semi-hydrated gypsum powder, wherein the micro-morphology is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 100-150 accounts for more than 95 percent of the total alpha-type semi-hydrated gypsum through SEM statistics and observation;
(3) Uniformly mixing fibrous alpha-type semi-hydrated gypsum powder with auxiliary materials (60 parts of 10-80 mu m cement and 40 parts of 20-61 mu m fly ash) according to a proportion of 2;
(4) Uniformly spreading the mixture in a disc granulator in batches, adding a mixed solution with the mass of 20% of the mixture as a binding agent in the rotating process to form balls, and obtaining a spheroid material with the particle size of 10-15 mm;
(5) The spheroid material was cured at a humidity of 90% for 24 hours to obtain a lightweight aggregate. Through detection, the aggregate barrel has the compression density of 12.4MPa and the bulk density of 610g/cm 3 The water absorption was 18%. After 15 cycles of dry and wet, the strength loss was 35.4%.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that modifications and improvements can be made thereto without departing from the scope of the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. The lightweight aggregate is characterized by being prepared from powder by a balling process, wherein the powder comprises 60-90 wt% of alpha-type semi-hydrated gypsum and 10-40 wt% of auxiliary materials, the micro-morphology of the alpha-type semi-hydrated gypsum is fibrous, and the alpha-type semi-hydrated gypsum with the length-diameter ratio of 20-300 accounts for more than 95% of the total alpha-type semi-hydrated gypsum;
the auxiliary material is a mixture of cement, fly ash and lime, and the mass ratio of the cement to the fly ash to the lime is (40-60): 20 to 40:0 to 20;
the preparation method of the lightweight aggregate comprises the following steps:
preparing the powder into a spheroid material, and maintaining the spheroid material in a wet environment;
the material for preparing the powder into the spheroid specifically comprises the following steps:
adding the powder into a disc granulator, and spraying a bonding agent during rolling granulation to obtain the powder;
wherein the binding agent is an aqueous solution of a retarder and a water repellent;
the mass percent of the retarder in the bonding agent is 1-2% of the mass of the solvent water, and the mass percent of the water repellent is 5-6.5% of the mass of the solvent water.
2. The lightweight aggregate according to claim 1, wherein the preparation method of the alpha-hemihydrate gypsum comprises the following steps:
mixing gypsum with water, and keeping the temperature of the obtained mixture for 1-4 h under the pressure of 0.198-0.882 MPa, the temperature of 120-180 ℃ and the stirring speed of 200-500r/min.
3. The lightweight aggregate according to claim 2, wherein the gypsum is one or more selected from the group consisting of desulfurized gypsum, phosphogypsum and titanium gypsum.
4. The lightweight aggregate according to claim 2, wherein the mass ratio of the gypsum to the water is 1 to 4 to 5.
5. The lightweight aggregate according to claim 1, wherein the particle diameter of the lightweight aggregate is from 8mm to 15mm.
6. A method of preparing a lightweight aggregate according to any one of claims 1 to 5, characterized by comprising the steps of:
preparing the powder into a spheroid material, and maintaining the spheroid material in a humid environment.
7. The preparation method according to claim 6, wherein the humid environment is an environment with humidity of more than 80%, and the curing time is 12 to 36h.
8. The preparation method according to claim 6 or 7, wherein the powder material is made into a spheroid material, in particular:
adding the powder into a disc granulator, and spraying a binding agent during rolling granulation to obtain the powder;
wherein the binding agent is an aqueous solution of a retarder and a water repellent.
9. The preparation method of claim 8, wherein the mass of the retarder in the bonding agent is 1 to 2 percent of the mass of the solvent water, and the mass of the water repellent is 5 to 6.5 percent of the mass of the solvent water;
and/or the retarder is selected from one or more of sodium tartrate, sodium citrate and sodium acetate;
and/or the water repellent is selected from one or more than two of ammonium borate, sodium methylsiliconate and dimethyl polysiloxane.
10. Use of a lightweight aggregate according to any one of claims 1 to 5 or prepared by the method according to any one of claims 6 to 9 in geopolymer concrete.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4018963A (en) * | 1974-05-21 | 1977-04-19 | Taisei Kensetsu Kabushiki Kaisha | Large lightweight gypsum article and a process for the production thereof |
| GB1536097A (en) * | 1976-11-29 | 1978-12-20 | Idemitsu Kosan Co | Granular gypsum and process for production of same |
| CN102745923A (en) * | 2011-04-22 | 2012-10-24 | 北京建筑材料科学研究总院有限公司 | Process for producing alpha type semi-hydrated gypsum by using industrial by-product gypsum |
| CN113121138A (en) * | 2020-01-16 | 2021-07-16 | 广东清大同科环保技术有限公司 | Gypsum-based baking-free aggregate |
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2021
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| US4018963A (en) * | 1974-05-21 | 1977-04-19 | Taisei Kensetsu Kabushiki Kaisha | Large lightweight gypsum article and a process for the production thereof |
| GB1536097A (en) * | 1976-11-29 | 1978-12-20 | Idemitsu Kosan Co | Granular gypsum and process for production of same |
| CN102745923A (en) * | 2011-04-22 | 2012-10-24 | 北京建筑材料科学研究总院有限公司 | Process for producing alpha type semi-hydrated gypsum by using industrial by-product gypsum |
| CN113121138A (en) * | 2020-01-16 | 2021-07-16 | 广东清大同科环保技术有限公司 | Gypsum-based baking-free aggregate |
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| CN114014620A (en) | 2022-02-08 |
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