CN112456843B - Fly ash chloride ion curing method - Google Patents
Fly ash chloride ion curing method Download PDFInfo
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- CN112456843B CN112456843B CN202011524385.3A CN202011524385A CN112456843B CN 112456843 B CN112456843 B CN 112456843B CN 202011524385 A CN202011524385 A CN 202011524385A CN 112456843 B CN112456843 B CN 112456843B
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- fly ash
- chloride ion
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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
- 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
- C04B20/023—Chemical treatment
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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
- C04B18/04—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
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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
- 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 relates to a fly ash chloride ion curing method, belonging to the field of building materials. The fly ash chloride ion curing method comprises the following steps: firstly, drying and aging the fly ash, secondly, adding 2-5% of curing agent, carrying out ball milling, and finally, stably aging to obtain the fly ash solidified by chloride ions. The fly ash chloride ion curing method has the advantages of low cost, simple process and good chloride ion curing effect, and solves the problem that the fly ash cannot be used due to overhigh chloride ion concentration when being used as a building material raw material.
Description
Technical Field
The invention relates to a fly ash chloride ion curing method, belonging to the field of building materials.
Background
Reinforced concrete is the most widely used building material in the world today due to its versatility and relatively low cost, and is commonly used in various construction engineering fields. Meanwhile, concrete structures are subject to erosion by various degradation factors under the action of the natural environment, such as surface abrasion, cracking due to salt crystallization in pores, and exposure to extreme temperature environments, such as fire or freezing, in addition to a sufficiently large load. Under the long-term influence of the service environment, the performance of the reinforced concrete structure can be gradually degraded, and the service life of the concrete structure is directly influenced.
Freeze-thaw damage, steel bar corrosion, carbonation and seawater corrosion are key reasons affecting the durability of concrete for a long time. Extensive data studies have shown that: the concrete structures at home and abroad are acted under the chloride environment for a long time to cause the early corrosion failure of the reinforcing steel bars, and even the failure and collapse accidents happen seriously, so that the economic loss is huge. The factors influencing the concrete damage are arranged according to the descending order of importance: corrosion of reinforcing steel bars, freeze-thaw damage and corrosion of environment. It can be seen that the corrosion of the steel bars is a direct cause of the damage of the concrete, and the corrosion of the chloride ions is a primary factor influencing the corrosion of the steel bars. The source of chloride ions generated in concrete generally has two routes; firstly, the chloride ions carried by the raw materials in the process of mixing the concrete and secondly, the chloride ions in the external environment penetrate through the pores and enter the interior of the concrete. Chloride ions in the external environment penetrate through the protective layer and are slowly accumulated on the surface of the steel bar, and the concentration of the chloride ions is increased until the chloride ions are diffused to the final critical concentration, so that the steel bar is damaged and corroded. At present, two technical measures are mainly adopted for the chlorine ion permeation resistance of concrete: firstly, a large amount of mineral admixture is used, and secondly, concrete with lower water-cement ratio is adopted. The chloride ions are mainly invaded into the coagulation stopper from the external environment slowly through tiny pores in the coagulation stopper, and the transmission process is a rather complicated physical and chemical process. The main reasons for the destruction of concrete in the chloride environment were analyzed: the chloride ions go deep into the gaps in the concrete and react with hydrated thioaluminate and calcium hydroxide to generate new salt substances, but the newly generated products have expanded volume and are not soluble with water, so that great stress is generated in the concrete gaps, and the concrete is cracked and damaged under the long-term action.
In the current stage of research on chloride ion curing, on one hand, the product performance is unstable, and the curing capability is poor; on the other hand, the concentration and the diffusion of chloride ions of building materials are reduced in the construction process, the required cost is high, and the difficulty is high; on the other hand, the existing form and components of the chloride ions in different building materials are complex, and the universal method has large difference on reducing the concentration of the chloride ions and can generate adverse effects on different material properties.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides the fly ash chloride ion curing method which is low in cost, simple in process and good in chloride ion curing effect.
In order to realize the purpose, the invention adopts the technical scheme that: a fly ash chloride ion curing method comprises the following steps: firstly, drying and aging the fly ash, secondly, adding a curing agent, performing ball milling again, and finally, performing stable aging to obtain the fly ash cured by chloride ions.
Researches show that the critical value of the content of chloride ions in concrete can be increased by adding the fly ash serving as a mineral admixture into the concrete, the permeability of the chloride ions is reduced, the binding capacity of the chloride ions is enhanced, and the pore shape and size distribution of a concrete matrix are improved; as the fly ash carries chloride ions, too much addition of the fly ash can carry too much chloride ions, and the performance and the service life of the concrete are influenced. The invention adopts the combination of physical and chemical curing methods, reduces the content of chloride ions in the fly ash and reaches the construction standard.
In a preferred embodiment of the method for solidifying fly ash by chloride ions according to the present invention, the addition amount of the solidifying agent is 1 to 10% by mass of the dried fly ash. The amount of curing agent affects the curing ability of the chloride ion. More preferably, when the addition amount of the curing agent is 2-5% of the mass of the dried fly ash, the curing capability of the chloride ions is better.
As a preferable embodiment of the fly ash chloride ion curing method, the curing agent comprises the following components in parts by weight: 65-75 parts of aluminum hydroxide, 16-23 parts of sodium aluminate, 6-11 parts of calcium sulfate, 2-6 parts of sodium hydroxide and 0.5-1 part of stearic acid.
Sulfate ions generated by calcium sulfate in the curing agent can be chemically combined with chloride ions to generate polysulfide hydrated calcium sulfoaluminate; until the sulfate ion is consumed, the chloride ion is not chemically combined with the aluminum hydroxide and the sodium aluminate to form a Friedel salt. Sodium hydroxide not only provides an alkaline environment, but also has induced polarization energy, and improves the ability of aluminum hydroxide and sodium aluminate to solidify chloride ions.
As a preferred embodiment of the fly ash chloride ion curing method, the drying temperature is 60-100 ℃, and the drying time is 4-8h.
The drying can not only remove the water in the fly ash, but also can not volatilize ammonium compounds, unstable carbides and the like contained in the fly ash, and simultaneously, the chloride in the fly ash is uniformly and stably distributed in the form of ionic salt.
As a preferred embodiment of the fly ash chloride ion curing method, the micro-morphology of the fly ash is a fly ash glass sphere, and the structure of the fly ash glass sphere is a hollow floating bead.
As a preferred embodiment of the fly ash chloride ion curing method, the ball milling rotation speed of the ball milling is 60-100r/min, and the ball milling time is 18-36h.
The structure of the fly ash glass sphere is a hollow floating bead, the activity of components inside the hollow floating bead is higher than that of components outside the floating bead, and the inside of the hollow floating bead is opened through mechanical ball milling, so that silicon oxide and aluminum oxide components with high activity inside the hollow floating bead adsorb a large amount of chloride ions.
As a preferred embodiment of the fly ash chloride ion curing method, the aging temperature of the stable aging is 15-35 ℃, and the aging time is 40-56h.
The fly ash of chloride ions is solidified in a physicochemical combination mode, and the best solidification effect can be achieved only by aging.
Compared with the prior art, the invention has the beneficial effects that: the invention adopts the fly ash chloride ion curing method combining physical and chemical curing, has low cost, simple process and good chloride ion curing effect, and solves the problem that the fly ash cannot be used due to overhigh chloride ion concentration when being used as a building material raw material.
Drawings
FIG. 1 is a flow chart of a fly ash chloride ion curing method.
Detailed Description
Example 1
The fly ash chloride ion curing method of the embodiment comprises the following steps: firstly, placing fly ash in a drying oven to dry for 6 hours at 80 ℃; secondly, adding a curing agent, and uniformly stirring; the addition amount of the curing agent is 1% of the mass of the dried fly ash, and the curing agent comprises the following components in parts by weight: 70 parts of aluminum hydroxide, 20 parts of sodium aluminate, 7 parts of calcium sulfate, 2.5 parts of sodium hydroxide and 0.5 part of stearic acid; then putting the mixture of the fly ash and the curing agent into a ball milling tank for ball milling for 24 hours at the speed of 80 r/min; and finally, aging the pulverized fuel ash subjected to ball milling for 48 hours at 25 ℃ to obtain the pulverized fuel ash solidified by chloride ions.
Example 2
The fly ash chloride ion curing method of the embodiment comprises the following steps: firstly, placing fly ash in a drying oven to dry for 6 hours at 80 ℃; secondly, adding a curing agent, and uniformly stirring; the addition amount of the curing agent is 3% of the mass of the dried fly ash, and the curing agent comprises the following components in parts by weight: 70 parts of aluminum hydroxide, 20 parts of sodium aluminate, 7 parts of calcium sulfate, 2.5 parts of sodium hydroxide and 0.5 part of stearic acid; then putting the mixture of the fly ash and the curing agent into a ball milling tank for ball milling for 24 hours at the speed of 80 r/min; and finally, aging the pulverized fuel ash subjected to ball milling for 48 hours at 25 ℃ to obtain the pulverized fuel ash solidified by chloride ions.
Example 3
The fly ash chloride ion curing method of the embodiment comprises the following steps: firstly, placing fly ash in a drying oven to be dried for 8 hours at 60 ℃; secondly, adding a curing agent, and uniformly stirring; the addition amount of the curing agent is 5 percent of the mass of the dried fly ash, and the curing agent comprises the following components in parts by weight: 65 parts of aluminum hydroxide, 23 parts of sodium aluminate, 11 parts of calcium sulfate, 6 parts of sodium hydroxide and 1 part of stearic acid; then putting the mixture of the fly ash and the curing agent into a ball milling tank for ball milling for 18 hours at the speed of 100 r/min; and finally, aging the pulverized fuel ash subjected to ball milling for 56 hours at 15 ℃ to obtain the pulverized fuel ash solidified by chloride ions.
Example 4
The fly ash chloride ion curing method of the embodiment comprises the following steps: firstly, putting the fly ash into a drying oven to be dried for 4 hours at the temperature of 100 ℃; secondly, adding a curing agent, and uniformly stirring; the addition amount of the curing agent is 2% of the mass of the dried fly ash, and the curing agent comprises the following components in parts by weight: 75 parts of aluminum hydroxide, 16 parts of sodium aluminate, 6 parts of calcium sulfate, 2 parts of sodium hydroxide and 0.8 part of stearic acid; then putting the mixture of the fly ash and the curing agent into a ball milling tank for ball milling for 36 hours at the speed of 60 r/min; and finally, aging the pulverized fuel ash subjected to ball milling for 40h at 35 ℃ to obtain the pulverized fuel ash solidified by chloride ions.
Example 5
The fly ash chloride ion curing method of the embodiment comprises the following steps: firstly, 10kg of fly ash is placed in a drying oven to be dried for 6 hours at the temperature of 80 ℃; secondly, adding a curing agent, and uniformly stirring; the addition amount of the curing agent is 10% of the mass of the dried fly ash, and the curing agent comprises the following components in parts by weight: 70 parts of aluminum hydroxide, 20 parts of sodium aluminate, 7 parts of calcium sulfate, 2.5 parts of sodium hydroxide and 0.5 part of stearic acid; then the mixture of the fly ash and the curing agent is put into a ball milling tank for ball milling for 24 hours at the speed of 80 r/min; and finally, aging the pulverized fuel ash subjected to ball milling for 48 hours at 25 ℃ to obtain the pulverized fuel ash solidified by chloride ions.
The content of chloride ions in the fly ash before and after solidification was measured, and the test results are shown in table 1.
TABLE 1
| Name (R) | Content of chloride ion before curing | Content of chloride ion after curing |
| Example 1 | 0.49％ | 0.30％ |
| Example 2 | 0.5％ | 0.28％ |
| Example 3 | 0.52％ | 0.29％ |
| Example 4 | 0.51％ | 0.28％ |
| Example 5 | 0.48％ | 0.30％ |
As can be seen from table 1, the chloride ion content of the fly ash after curing was reduced by 45% relative to the content before curing. The method meets GB50164-2011 concrete quality control standard, and the content of water-soluble chloride ions in the reinforced concrete is required to be lower than 0.3% in a dry environment.
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 (4)
1. A fly ash chloride ion curing method is characterized by comprising the following steps: firstly, drying and aging the fly ash, secondly, adding a curing agent, performing ball milling, and finally, stably aging to obtain the fly ash cured by chloride ions;
the addition amount of the curing agent is 2-5% of the mass of the dried fly ash;
the curing agent comprises the following components in parts by weight: 65-75 parts of aluminum hydroxide, 16-23 parts of sodium aluminate, 6-11 parts of calcium sulfate, 2-6 parts of sodium hydroxide and 0.5-1 part of stearic acid;
the microscopic morphology of the fly ash is a fly ash glass sphere, and the structure of the fly ash is hollow floating beads.
2. The fly ash chloride ion curing method of claim 1, wherein the drying temperature is 60-100 ℃ and the drying time is 4-8h.
3. The fly ash chloride ion solidification method according to claim 1, wherein the ball milling rotation speed of the ball milling is 60-100r/min, and the ball milling time is 18-36h.
4. The fly ash chloride ion curing method of claim 1, wherein the stable aging is carried out at an aging temperature of 15-35 ℃ for an aging time of 40-56 hours.
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| CN202011524385.3A CN112456843B (en) | 2020-12-22 | 2020-12-22 | Fly ash chloride ion curing method |
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| CN202011524385.3A CN112456843B (en) | 2020-12-22 | 2020-12-22 | Fly ash chloride ion curing method |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101239792A (en) * | 2008-03-12 | 2008-08-13 | 中南大学 | Additive for increasing cement-base material solidifying dissociative chlorine ion capability and applying method thereof |
| WO2010079955A2 (en) * | 2009-01-07 | 2010-07-15 | Kim Young-Il | Soil pavement composition and soil pavement construction method using the same |
| CN109824288A (en) * | 2019-03-19 | 2019-05-31 | 武汉理工大学 | A kind of cement-based material chlorine-solidifying agent and preparation method thereof |
| CN111410460A (en) * | 2019-12-17 | 2020-07-14 | 李韦皞 | Method for immobilizing heavy metals and chloride in incineration fly ash of hazardous waste |
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2020
- 2020-12-22 CN CN202011524385.3A patent/CN112456843B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101239792A (en) * | 2008-03-12 | 2008-08-13 | 中南大学 | Additive for increasing cement-base material solidifying dissociative chlorine ion capability and applying method thereof |
| WO2010079955A2 (en) * | 2009-01-07 | 2010-07-15 | Kim Young-Il | Soil pavement composition and soil pavement construction method using the same |
| CN109824288A (en) * | 2019-03-19 | 2019-05-31 | 武汉理工大学 | A kind of cement-based material chlorine-solidifying agent and preparation method thereof |
| CN111410460A (en) * | 2019-12-17 | 2020-07-14 | 李韦皞 | Method for immobilizing heavy metals and chloride in incineration fly ash of hazardous waste |
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