CN112592087B - Admixture and preparation method and application thereof - Google Patents

Admixture and preparation method and application thereof Download PDF

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Publication number
CN112592087B
CN112592087B CN202011533976.7A CN202011533976A CN112592087B CN 112592087 B CN112592087 B CN 112592087B CN 202011533976 A CN202011533976 A CN 202011533976A CN 112592087 B CN112592087 B CN 112592087B
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parts
zeolite
admixture
fly ash
drying
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CN112592087A (en
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饶睦敏
姚勇
吴志超
黎石竹
汪牧
陈慧琳
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Guangdong Tsingda Tongke Environmental Protection Technology Co ltd
Guangdong Energy Group Science And Technology Research Institute Co ltd
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Guangdong Tsingda Tongke Environmental Protection Technology Co ltd
Guangdong Energy Group Science And Technology Research Institute Co ltd
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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
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039—Premixtures of ingredients
    • 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
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/047—Zeolites
    • 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
    • C04B18/04—Waste materials; Refuse
    • C04B18/06—Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
    • C04B18/08—Flue dust, i.e. fly ash
    • 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
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/026—Comminuting, e.g. by grinding or breaking; Defibrillating fibres other than asbestos
    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Abstract

The invention discloses an admixture, and relates to the technical field of concrete admixtures. The admixture comprises the following components in parts by weight: 50-60 parts of fly ash, 15-20 parts of modified zeolite, 10-15 parts of steel slag, 5-10 parts of desulfurized gypsum, 1-5 parts of hydrated lime and 1-5 parts of additive; the preparation method of the modified zeolite comprises the following steps: (1) drying and crushing natural zeolite to obtain crushed zeolite; (2) roasting the crushed zeolite prepared in the step (1) at a certain temperature, cooling the roasted zeolite in cold water, and drying to obtain the modified zeolite. The admixture provided by the invention has low cost and no pollution, realizes good double combination of environmental benefit and economic benefit, and accords with sustainable development of resources.

Description

Admixture and preparation method and application thereof
Technical Field
The invention relates to the technical field of concrete admixtures, in particular to an admixture and a preparation method and application thereof.
Background
The fly ash is fine ash collected from coal-fired flue gas, and is a solid waste discharged by coal-fired power generation of a thermal power plant. The fly ash is mainly composed of active SiO2And Al2O3The composition is widely used in the aspects of cement production, concrete preparation and the like; but due to free Cl in the high-chlorine fly ash-Higher content of Cl caused by using it as an admixture for cement or concrete-The content exceeds the standard, thereby corroding the reinforcing steel bars and shadows in the concreteMaking the concrete member safe; leading to the storage of a large amount of high chlorine fly ash, seriously polluting the surrounding land environment and causing the waste of available resources.
At present, most researches mainly adopt methods of reducing water-cement ratio, doping a large amount of mineral admixtures and the like to improve the compactness of concrete so as to reduce the corrosion of chloride ions to steel bars in the concrete; although the improvement of the compactness of the concrete has obvious barrier effect on the permeation of chloride ions, the risk brought by the cracking of the concrete is ignored; at the same time, the use of higher quality mineral admixtures results in greater costs. Therefore, the method for effectively curing the chloride ions in the concrete can provide a way for utilizing high-chlorine fly ash resources.
Disclosure of Invention
Based on the above, the invention aims to overcome the defects of the prior art and provide the admixture which is low in cost, free of pollution and prepared by utilizing the high-chlorine fly ash.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: an admixture comprises the following components in parts by weight: 50-60 parts of fly ash, 15-20 parts of modified zeolite, 10-15 parts of steel slag, 5-10 parts of desulfurized gypsum, 1-5 parts of hydrated lime and 1-5 parts of additive; the preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite to obtain crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature, cooling the roasted zeolite in cold water, and drying to obtain the modified zeolite.
According to the invention, the zeolite modified by a high-temperature roasting process is doped with the high-chlorine fly ash to prepare the admixture, the property that the natural zeolite can adsorb chloride ions in an aqueous solution is popularized to the property that the free chloride ions in the concrete are solidified, the obtained admixture can improve the strength of the concrete, and the free chloride ions in the concrete can be effectively solidified without affecting the property of the concrete.
The invention adopts Ca (OH)2Excitation of the Activity of high chlorine fly ash, Ca (OH)2Glass body mixed with fly ashSiO in (2)2And Al2O3The volcanic ash reaction is carried out to generate C-S-H and C-A-H, and the internal free chlorine ions can be physically adsorbed in the surface and the inner space of the C-S-H gel and can also be in the form of chlorine-oxygen compounds (3 CaO. CaCl)2·xH2O) chemisorbed or displaced into the structure. And then the calcined and modified zeolite is doped, so that the moisture on the surface and the moisture hidden in the framework are lost, the impurities such as internal organic molecules and the like are removed at high temperature, the pore diameter of the pore channel is enlarged, and the adsorption capacity to chloride ions is increased. Meanwhile, the main chemical component of the natural zeolite is SiO2And Al2O3Under the alkaline excitation in concrete, internal active Si and Al react with Ca (OH) provided in the hydration process of cement2The secondary reaction is carried out to generate C-S-H gel, thereby improving the compactness and impermeability of the concrete. Meanwhile, because of the ion exchange property and strong adsorption property of the zeolite, the harm of alkali-aggregate reaction in concrete can be effectively inhibited. Therefore, the blending of the modified zeolite and the high-chlorine fly ash for preparing the blending material provides more opportunities for curing chloride ions while improving various performances of concrete.
The invention puts the calcined zeolite into cold water for flash cooling, so that thermal shock is formed, the generation of structural defects and the separation of impurities are facilitated, and-OH free radicals lost by calcination are adsorbed in the activated zeolite again under the water treatment, so that the activity of the zeolite is improved.
Preferably, in the step (1) of the preparation method of the modified zeolite, the drying temperature is 70-80 ℃, and the mesh number of the crushed zeolite is 40-60 meshes.
When the modified zeolite is prepared, the modified zeolite is dried, crushed and then roasted, so that the problem that the adsorption performance of the modified zeolite is influenced because the structure is locally damaged due to rapid evaporation and rapid temperature rise of water originally remained in holes and channels inside crystals can be avoided.
Preferably, in the step (2) of the preparation method of the modified zeolite, the roasting temperature is 400-600 ℃, the roasting time is 25-35min, and the water content of the modified zeolite obtained after drying is less than 1%.
In the preparation method of the modified zeolite, the purpose of high-temperature roasting is to remove organic matters in cavities and pore channels of the modified zeolite.
Preferably, the admixture comprises the following components in parts by weight: 57 parts of fly ash, 18 parts of modified zeolite, 11 parts of steel slag, 8 parts of desulfurized gypsum, 3 parts of slaked lime and 3 parts of additive.
Through a great deal of creative research, the inventor finally determines the optimal weight part of the modified zeolite in the process of preparing the admixture and the optimal weight part matched with the high-chlorine fly ash, the hydrated lime and the like, and the admixture prepared at the moment can better improve the performance of the admixture and can best cure free chloride ions in the concrete.
Preferably, the content of chloride ions in the fly ash is more than 0.5%, the additive is a mixture of aluminate and a water reducing agent, wherein the mass ratio of the aluminate to the water reducing agent is as follows: aluminate: 1-2 parts of water reducing agent and 0.2-1 part of water reducing agent.
The admixture is a mixture of aluminate and a water reducing agent, and the water reducing agent and the aluminate are cooperatively used to improve the accelerating action of the aluminate accelerator and reduce the loss of strength.
Preferably, the aluminate of the present invention is one of sodium aluminates.
Preferably, the water reducing agent is at least one of lignosulfonate, sulfamate, fatty acid and polycarboxylate.
In addition, the invention also provides a preparation method of the admixture, which comprises the following steps:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use;
(b) pre-grinding the fly ash and the hydrated lime dried in the step (a) to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag in the step (a), the desulfurized gypsum and the additive, performing ball milling, and uniformly stirring to obtain the admixture.
According to the invention, materials such as desulfurized gypsum, hydrated lime and the like are mixed with the high-chlorine fly ash for ball milling, so that the grinding and homogenizing effects are more obvious; the mixing and grinding mode has the functions of stirring uniformly and grinding, and increases the activity excitation effect of mechanical force on materials, so that the grading and activity synergistic dual optimization of the high-chlorine fly ash, the zeolite and other material components is facilitated, the high-chlorine fly ash and the zeolite can fully play the beneficial effects in the admixture, and the admixture can be more efficiently utilized;
preferably, in the step (a), the moisture content of the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive obtained after drying is less than 1%.
The fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive are firstly dried until the water content is less than 1 percent, so that the agglomeration phenomenon of the materials is avoided, and the next step of ball milling is facilitated.
Preferably, in the step (b), the time of the pre-grinding treatment is 30-40 min; in the step (c), the ball milling time is 3-4 h.
The fineness of the admixture prepared by the invention is determined according to actual requirements, and the fineness standard of the admixture prepared by the invention is as follows: the specific surface area is 700-800m2Per kg; wherein, when the number of days is 7d, the activity index is 77.92-85.16%; at 28d, the activity index is 95.34-105.23%.
Meanwhile, the invention also provides the application of the admixture in concrete.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention utilizes the wastes such as high-chlorine fly ash which are difficult to be comprehensively utilized as main raw materials to prepare the admixture, provides an effective utilization way for the admixture, improves the environment, reduces the pollution, further reduces the cost for producing the admixture, realizes the double combination of good environmental benefit and economic benefit, and accords with the sustainable development of resources.
(2) The fineness of the admixture is smaller than that of cement particles, so that the pore structure of concrete can be effectively improved, and the compactness of the concrete is improved.
(3) According to the invention, the modified zeolite and the high-chlorine fly ash are adopted to prepare the admixture, so that the strength and impermeability of concrete can be improved, the harm of alkali-aggregate reaction in the concrete is inhibited, the construction performance and the like are improved, and free chloride ions in the fly ash can be effectively cured while the performance of the concrete is not influenced; according to a method for measuring the content of chloride ions in a concrete mixture in water transport engineering concrete test procedure JTJ 270, when a high-chlorine fly ash admixture and silicate cement are prepared into C30 concrete according to the mass ratio of 1: 9-1: 1, the content of free chloride ions in the concrete can be reduced to 0.05-0.02%.
(4) The high-chlorine fly ash used in the invention has high content of free Cl < - > and is difficult to be directly applied to the aspect of admixture of cement or concrete, so that a large amount of high-chlorine fly ash is piled and placed, and the surrounding land environment is seriously polluted. In the preparation of the traditional fly ash admixture, the fineness of waste residue powder is larger, the energy consumption is higher, and the performance in curing chloride ions is poorer. The technical process of the invention can prepare the admixture with the curable chloride ion performance by taking the high-chlorine fly ash, the natural zeolite, the steel slag and other solid wastes as main raw materials, provides an effective utilization way for the high-chlorine fly ash, reduces pollution, further reduces the cost for producing the admixture, realizes good double combination of environmental benefit and economic benefit, and accords with sustainable development of resources.
Detailed Description
To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.
Examples 1-4 are provided herein, and the parts by weight of the specific examples 1-4 are selected as shown in table 1:
TABLE 1 selection of parts by weight of specific examples 1-4
Components Example 1 Example 2 Example 3 Example 4
Fly ash 50 60 55 57
Modified zeolite 15 20 16 18
Steel slag 10 15 13 11
Desulfurized gypsum 5 10 7 8
Hydrated lime 1 5 2 3
Additive agent 1 5 2 3
Aluminate: water reducing agent 1:0.2 2:1 1:1 1.5:0.5
Example 1
In one embodiment of the present application, the method for preparing the admixture comprises the following steps:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use, wherein the water content after drying is less than 1%;
(b) pre-grinding the coal ash and the hydrated lime dried in the step (a) for 30min to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag in the step (a), the desulfurized gypsum and the additive, performing ball milling for 3 hours, and uniformly stirring to obtain the admixture.
The preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite, wherein the drying temperature is 70 ℃, and the mesh number of the crushed zeolite is 40 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature of 400 ℃ for 35min, cooling the roasted zeolite in cold water, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
Example 2
In one embodiment of the present application, the method for preparing the admixture comprises the following steps:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use, wherein the water content after drying is less than 1%;
(b) pre-grinding the fly ash and the hydrated lime dried in the step (a) for 40min to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag in the step (a), the desulfurized gypsum and the additive, performing ball milling for 4 hours, and uniformly stirring to obtain the admixture.
The preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite at the drying temperature of 80 ℃, wherein the mesh number of the crushed zeolite is 60 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature of 600 ℃ for 25min, cooling the roasted zeolite in cold water, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
Example 3
In one embodiment of the present application, the method for preparing the admixture comprises the following steps:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use, wherein the water content after drying is less than 1%;
(b) pre-grinding the fly ash and the hydrated lime dried in the step (a) for 35min to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag, the desulfurized gypsum and the additive in the step (a), performing ball milling for 4 hours, and uniformly stirring to obtain the admixture.
The preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite at the drying temperature of 80 ℃, wherein the mesh number of the crushed zeolite is 60 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature, wherein the roasting temperature is 500 ℃, the roasting time is 30min, cooling the roasted zeolite in cold water, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
Example 4
In one embodiment of the present application, the method for preparing the admixture comprises the following steps:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use, wherein the water content after drying is less than 1%;
(b) pre-grinding the coal ash and the hydrated lime dried in the step (a) for 30min to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag in the step (a), the desulfurized gypsum and the additive, performing ball milling for 4 hours, and uniformly stirring to obtain the admixture.
The preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite at the drying temperature of 80 ℃, wherein the mesh number of the crushed zeolite is 40 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature, wherein the roasting temperature is 500 ℃, the roasting time is 30min, cooling the roasted zeolite in cold water, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
Meanwhile, the application sets comparative examples, and specific comparative examples 1 to 3 set as follows:
the zeolite used in comparative example 1 was an unmodified natural zeolite, and the remaining components, parts by weight, and preparation methods were completely the same as in example 4;
comparative example 2
The modified zeolite in comparative example 2 was prepared by a different method, and the remaining components, parts by weight and preparation method were completely the same as in example 4;
the preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite at the drying temperature of 80 ℃, wherein the mesh number of the crushed zeolite is 40 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature of 350 ℃ for 30min, cooling the roasted zeolite in cold water, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
The modified zeolite in comparative example 3 was prepared by a different method, and the remaining components, parts by weight and preparation method were completely the same as in example 4;
the preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite at the drying temperature of 80 ℃, wherein the mesh number of the crushed zeolite is 40 meshes to obtain the crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at a certain temperature of 500 ℃ for 30min, cooling the roasted zeolite at normal temperature, drying to obtain the modified zeolite, and drying to obtain the modified zeolite with the water content of less than 1%.
Test example 1 concrete Performance test
(1) Determination of chloride ion content in concrete mixture
Test standards: according to the method for measuring the content of chloride ions in the concrete mixture in Water transport engineering concrete test Specification JTJ 270.
The test process comprises the following steps: the high-chlorine fly ash admixture prepared in the embodiments 1-4 and the comparative examples 1-3 of the invention and the silicate cement are mixed according to the mass ratio of 1:5 to prepare C30 concrete, and the content of internal free chloride ions is tested.
And (3) test results: the test results are shown in table 2:
TABLE 2 test results of examples 1 to 4 and comparative examples 1 to 3
Figure BDA0002850076130000091
As shown in Table 2, after the high-chlorine fly ash admixtures prepared in examples 1-4 are used for preparing C30 concrete, the content of internal free chloride ions is 0.05% or less, and the content of chloride ions is reduced, so that the corrosion to reinforcing steel bars in the concrete is reduced; the zeolite adopted in the comparative example 1 is natural zeolite which is not modified, and after the prepared high-chlorine fly ash admixture is used for preparing C30 concrete, the content of internal free chloride ions is 0.58 percent; in the preparation method of the modified zeolite in comparative example 2, the calcination temperature was 350 ℃, which is not within the preferred range of the present invention; the modified zeolite of comparative example 3 was prepared by cooling at room temperature, which is not within the preferred range of the present invention; as can be seen from the data of comparative examples 2 and 3, the calcination temperature during the preparation of the modified zeolite has a large influence on the modified zeolite, thereby affecting the chloride ion content in the prepared concrete.
(2) Activity testing of fly ash admixtures
Test standards: according to the activity test method of the admixture in GB/T1596 fly ash for cement and concrete.
The test process comprises the following steps: the activity index refers to the ratio of the standard mortar strength of the fly ash admixture replacing 30% of cement to the standard mortar strength; the activity of the high-chlorine fly ash admixtures prepared in examples 1-4 and comparative examples 1-3 of the present invention was tested.
And (3) test results: the test results are shown in table 3:
TABLE 3 results of Activity test of examples 1 to 4 and comparative examples 1 to 3
Figure BDA0002850076130000101
As can be seen from the test data in Table 3, the high chlorine fly ash admixtures prepared in examples 1-4 have higher activity, the 7-day activity index is 77.92-85.16%, and the 28-day activity index is 95.34-105.23%. In comparative examples 1-3, the high-chlorine fly ash admixtures are prepared by respectively doping unmodified natural zeolite and zeolite modified by adopting a low-temperature roasting and normal-temperature cooling process, and comparative test data show that the admixtures in comparative examples 1-3 have lower activity, the activity index is 69.81-76.23% in 7 days, and the activity index is 82.52-87.14% in 28 days. Therefore, the high-chlorine fly ash admixture prepared by the technical process has the advantage of large activity index.
(3) Concrete strength test
Test standards: the method is based on the strength test method of the concrete in the national standard GB/T50081 of the test method standard for mechanical properties of common concrete.
The test process comprises the following steps: the high-chlorine fly ash admixtures prepared in examples 1-4 and comparative examples 1-3 were mixed with Portland cement 42.5 at a mass ratio of 1:1 to prepare C30 concrete, and the strength of the concrete was tested.
And (3) test results: the test results are shown in table 4:
TABLE 4 Strength test results of examples 1 to 4 and comparative examples 1 to 3
Figure BDA0002850076130000102
Figure BDA0002850076130000111
As can be seen from the data in Table 4, the compressive strength of the C30 concrete prepared from the high-chlorine fly ash admixture prepared in the examples 1-4 can reach more than 34.9MPa in 28 days, and is higher than the strength of the concrete prepared from pure cement; the concrete prepared by the admixture of the comparative examples 1-3 has lower 28-day compressive strength which is only about 30 MPa. The high-chlorine fly ash admixture prepared by the invention has the advantages of higher compactness, small water demand, higher activity index and the like, is used for preparing concrete by replacing cement, and is beneficial to improving the strength and durability of the concrete.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (9)

1. The admixture is characterized by comprising the following components in parts by weight: 50-60 parts of fly ash, 15-20 parts of modified zeolite, 10-15 parts of steel slag, 5-10 parts of desulfurized gypsum, 1-5 parts of hydrated lime and 1-5 parts of additive; the preparation method of the modified zeolite comprises the following steps:
(1) drying and crushing natural zeolite to obtain crushed zeolite;
(2) roasting the crushed zeolite prepared in the step (1) at the temperature of 400-600 ℃, cooling the roasted zeolite in cold water, and drying to obtain the modified zeolite;
the content of chloride ions in the fly ash is more than 0.5%, the additive is a mixture of aluminate and a water reducing agent, wherein the mass ratio of the aluminate to the water reducing agent is as follows: aluminate: 1-2 parts of water reducing agent and 0.2-1 part of water reducing agent.
2. The admixture of claim 1, wherein in step (1) of said process for preparing a modified zeolite, the drying temperature is from 70 ℃ to 80 ℃ and the mesh size of the zeolite after crushing is from 40 to 60 mesh.
3. The admixture of claim 1, wherein in step (2) of the process for preparing modified zeolite, the modified zeolite has a calcination time of 25-35min and a water content of less than 1% after drying.
4. The admixture according to any one of claims 1 to 3, comprising the following components in parts by weight: 57 parts of fly ash, 18 parts of modified zeolite, 11 parts of steel slag, 8 parts of desulfurized gypsum, 3 parts of slaked lime and 3 parts of additive.
5. The admixture according to claim 1, wherein said water reducing agent is at least one of lignosulfonate, sulfamate, fatty acid, and polycarboxylate.
6. A process for the preparation of an admixture according to any one of claims 1 to 5 comprising the steps of:
(a) drying the fly ash, the steel slag, the desulfurized gypsum, the hydrated lime and the additive for later use;
(b) pre-grinding the fly ash and the hydrated lime dried in the step (a) to obtain a mixture A;
(c) and (3) mixing the modified zeolite, the mixture A obtained in the step (b), the dried steel slag in the step (a), the desulfurized gypsum and the additive, performing ball milling, and uniformly stirring to obtain the admixture.
7. The method of manufacturing an admixture according to claim 6, wherein in step (a), the moisture content of the fly ash, steel slag, desulfurized gypsum, hydrated lime and admixture obtained after drying is less than 1%.
8. The admixture preparation method of claim 6, wherein in step (b), the time of the pre-milling treatment is 30-40 min; in the step (c), the ball milling time is 3-4 h.
9. Use of an admixture according to any of claims 1 to 5 in concrete.
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