CN114644476A - Concrete aggregate with core-shell structure and preparation method and application thereof - Google Patents
Concrete aggregate with core-shell structure and preparation method and application thereof Download PDFInfo
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- CN114644476A CN114644476A CN202210269745.2A CN202210269745A CN114644476A CN 114644476 A CN114644476 A CN 114644476A CN 202210269745 A CN202210269745 A CN 202210269745A CN 114644476 A CN114644476 A CN 114644476A
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- 239000011258 core-shell material Substances 0.000 title claims abstract description 60
- 238000002360 preparation method Methods 0.000 title claims abstract description 41
- 239000002910 solid waste Substances 0.000 claims abstract description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000002994 raw material Substances 0.000 claims abstract description 38
- 239000011398 Portland cement Substances 0.000 claims abstract description 23
- 231100001261 hazardous Toxicity 0.000 claims abstract description 16
- 229910021487 silica fume Inorganic materials 0.000 claims abstract description 16
- 239000002253 acid Substances 0.000 claims abstract description 14
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims description 21
- 239000002245 particle Substances 0.000 claims description 16
- 239000002002 slurry Substances 0.000 claims description 16
- 238000001035 drying Methods 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 230000000694 effects Effects 0.000 claims description 6
- 239000003245 coal Substances 0.000 claims description 5
- 238000010276 construction Methods 0.000 claims description 4
- 229910001385 heavy metal Inorganic materials 0.000 abstract description 15
- 150000002500 ions Chemical class 0.000 abstract description 10
- 238000002386 leaching Methods 0.000 abstract description 10
- 238000007596 consolidation process Methods 0.000 abstract description 8
- 239000000203 mixture Substances 0.000 abstract description 6
- 239000000843 powder Substances 0.000 abstract description 5
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- 238000005056 compaction Methods 0.000 abstract description 2
- 238000007789 sealing Methods 0.000 abstract description 2
- 230000007704 transition Effects 0.000 abstract description 2
- 239000011162 core material Substances 0.000 description 49
- 239000011257 shell material Substances 0.000 description 42
- 238000012360 testing method Methods 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 10
- JQJCSZOEVBFDKO-UHFFFAOYSA-N lead zinc Chemical compound [Zn].[Pb] JQJCSZOEVBFDKO-UHFFFAOYSA-N 0.000 description 7
- 239000003513 alkali Substances 0.000 description 6
- 239000004568 cement Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 238000007580 dry-mixing Methods 0.000 description 5
- 238000000227 grinding Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000002920 hazardous waste Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000003469 silicate cement Substances 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 238000003321 atomic absorption spectrophotometry Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000012633 leachable Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000012536 packaging technology Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009270 solid waste treatment Methods 0.000 description 1
- 238000007655 standard test method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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Classifications
-
- 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
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
- C04B20/1077—Cements, e.g. waterglass
-
- 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
- C04B28/02—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 hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- 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
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention belongs to the technical field of concrete aggregate, and particularly relates to a core-shell structure concrete aggregate as well as a preparation method and application thereof. The invention provides a concrete aggregate with a core-shell structure, which comprises an inner core and a shell wrapping the inner core; the preparation raw materials of the inner core comprise: hazardous solid waste powder and water; the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water. In the invention, the preparation raw materials of the inner core initially form a stable consolidation body; the shell composition can perform volcanic ash reaction with active components in the dangerous solid waste in the kernel, improve the microstructure of an interface transition region, promote the tight combination of the kernel and the shell, realize the stable solid waste sealing in the shell, and effectively prevent the surface leaching of heavy metal ions; in addition, the shell composition has large early shrinkage, and can play a role in physical compaction, further improve the mechanical strength of the core-shell structure concrete aggregate and realize the preparation of high-quality aggregate.
Description
Technical Field
The invention belongs to the technical field of concrete aggregate, and particularly relates to a core-shell structure concrete aggregate as well as a preparation method and application thereof.
Background
The dangerous solid waste comprises tailings, red mud, coal gangue and other substances. At present, the treatment mode of dangerous solid waste is mainly underground landfill, however, harmful components such as alkali liquor, heavy metal ions and the like in the dangerous waste after landfill treatment are easy to leach out, and soil and underground water pollution is caused. Meanwhile, the danger of dam break exists due to the large amount of accumulated dangerous solid waste. Therefore, a safe disposal of a large amount of hazardous solid waste is urgently needed.
The cement-based material solidification dangerous solid waste is an effective solid waste treatment mode, on one hand, the main hydration product C-S-H gel of the cement has better chemical consolidation effect on heavy metal ions and the like; on the other hand, the excellent impermeability of the cement-based material also provides physical packaging conditions for dangerous solid wastes, and reduces the leaching risk of harmful components. However, the existing packaging technology mainly uses the dangerous solid wastes as auxiliary cementing materials (or aggregates) to directly prepare cement-based materials, so that the surface leaching behavior of heavy metal ions cannot be fundamentally inhibited, and the problems of the dangerous solid wastes and insufficient consolidation force of the cement-based materials for consolidation exist.
Disclosure of Invention
In view of the above, the present invention aims to provide a core-shell structure concrete aggregate, which has high consolidation strength of a hazardous solid waste and a cement-based material for consolidation, and can fundamentally and substantially inhibit surface leaching behavior of heavy metal ions in the hazardous solid waste.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
the invention provides a concrete aggregate with a core-shell structure, which comprises an inner core and a shell wrapping the inner core;
the preparation raw materials of the inner core comprise: dangerous solid waste powder and water;
the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water.
Preferably, the hazardous solid waste comprises one or more of red mud, tailings and coal gangue.
Preferably, in the preparation raw materials of the inner core, the mass ratio of the dangerous solid waste powder to water is 1000: (200-400).
Preferably, the preparation raw material of the inner core also comprises a curing agent; the curing agent comprises ordinary portland cement.
Preferably, the average particle size of the dangerous solid waste powder is less than or equal to 100 mu m.
Preferably, in the raw materials for preparing the shell, the mass ratio of the portland cement to the silica fume is 1000: (100 to 280); the mass ratio of the portland cement to the polycarboxylic acid water reducing agent is 1000: (15-30); the mass ratio of the portland cement to water is 1000: (170-220).
Preferably, the average particle size of the silica fume is 300nm, and the activity index is more than or equal to 100 percent.
Preferably, the diameter of the inner core is 5-20 mm; the thickness of shell is 1 ~ 3 mm.
The invention also provides a preparation method of the concrete aggregate with the core-shell structure, which comprises the following steps:
mixing and curing the preparation raw materials of the kernel to obtain the kernel;
mixing the raw materials for preparing the shell to obtain shell slurry;
and coating the inner core with the shell slurry, and drying to obtain the core-shell structure concrete aggregate.
The invention also provides the application of the core-shell structure concrete aggregate in the technical scheme or the core-shell structure concrete aggregate prepared by the preparation method in the technical scheme in engineering construction.
The invention provides a core-shell structure concrete aggregate, which comprises an inner core and a shell wrapping the inner core; the preparation raw materials of the inner core comprise: hazardous solid waste powder and water; the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water. In the invention, the preparation raw material of the inner core initially forms a structure-stable consolidation body; the shell components can perform volcanic ash reaction with active components (such as amorphous (noncrystalline) silicon dioxide) in dangerous solid waste (such as one or more of red mud, lead-zinc tailings, copper tailings and coal gangue) in the kernel to generate C-S-H gel, improve the microstructure of an interface transition region, promote the tight combination of the kernel and the shell, improve the consolidation force, realize the stable solid sealing of the dangerous solid waste in the shell and effectively prevent the surface leaching of heavy metal ions; in addition, the shell composition has large early shrinkage, can play a role of physical compaction, further improves the mechanical strength of the concrete aggregate with the core-shell structure, realizes the preparation of high-quality aggregate, and meets the mechanical property requirement of the concrete aggregate in C15-C25 structural engineering.
The test results of the embodiment show that the core-shell structure concrete aggregate provided by the invention can effectively inhibit leaching of dangerous solid waste alkali liquor and heavy metals, and the single-particle aggregate has high average compressive strength and meets the mechanical property requirements of the concrete aggregate in C15-C25 structural engineering.
Drawings
FIG. 1 is a diagram showing a concrete aggregate having a core-shell structure obtained in example 1;
FIG. 2 is an SEM image of the interface between the inner core and the outer shell of the concrete aggregate with the core-shell structure obtained in example 1.
Detailed Description
The invention provides a concrete aggregate with a core-shell structure, which comprises an inner core and a shell wrapping the inner core;
the preparation raw materials of the inner core comprise: hazardous solid waste and water;
the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water.
In the present invention, unless otherwise specified, each of the substances is a commercially available product well known to those skilled in the art.
In the invention, the core-shell structure concrete aggregate comprises an inner core and an outer shell wrapping the inner core.
In the present invention, the preparation raw material of the core comprises: hazardous solid waste and water.
In the present invention, the hazardous solid waste preferably comprises one or more of red mud, tailings and coal gangue. In the present invention, the tailings preferably comprise one or more of lead zinc tailings and copper tailings. The source of the hazardous solid waste is not particularly limited in the present invention, and any source known to those skilled in the art may be used.
In the present invention, the average particle size of the hazardous solid waste is preferably 100 μm or less.
In the present invention, in the preparation raw material of the inner core, the mass ratio of the hazardous solid waste to water is preferably 1000: (200-400), more preferably 1000: (220-370), more preferably 1000: (250-350).
In the present invention, the raw material for preparing the core preferably further comprises a curing agent. In the present invention, the curing agent preferably includes ordinary portland cement. In the present invention, the portland cement is preferably 42.5 grade. In the invention, the mass ratio of the dangerous solid waste to the curing agent is preferably more than or equal to 20: 1.
in the invention, the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water.
In the present invention, the portland cement is preferably of grade 52.5.
In the present invention, the average particle size of the silica fume is preferably 300nm, and the activity index is preferably equal to or greater than 100%.
In the present invention, the mass ratio of the portland cement to silica fume is preferably 1000: (100 to 280), more preferably 1000: (120 to 250), more preferably 1000: (150-230). In the present invention, the mass ratio of the portland cement to the polycarboxylic acid water reducing agent is preferably 1000: (15-30), more preferably 1000: (18-28), more preferably 1000: (20-25). In the present invention, in the raw materials for preparing the shell, the mass ratio of the portland cement to water is preferably 1000: (170-220), more preferably 1000: (180-210), more preferably 1000: (185-205).
In the present invention, the diameter of the inner core is preferably 5 to 20mm, and more preferably 5 to 18 mm. In the invention, the thickness of the shell is preferably 1-3 mm, and more preferably 1-2.5 mm.
In the invention, the particle stacking system formed by the raw materials for preparing the shell has a more microscopic structureDensification can provide more compact and stronger packaging conditions for dangerous solid waste, effectively prevents the leaching of alkali liquor and/or heavy metal ions in the dangerous solid waste, and realizes the safe recycling of the dangerous solid waste. In addition, the invention recycles the dangerous solid wastes as the preparation raw material of the concrete aggregate with the core-shell structure, can effectively relieve the current situation of the shortage of natural sandstone aggregate, and simultaneously realizes the large consumption of the dangerous solid wastes (the application amount of the dangerous solid wastes as mineral admixture in the concrete is only 50-120 kg/m)3The invention can be used as the inner core of the concrete aggregate with the core-shell structure and can absorb 600kg/m3The above hazardous waste).
The core-shell structure concrete aggregate provided by the invention effectively solves the problems, does not need dealkalization, heavy metal removal or sintering, and has low curing cost; the application amount of the mineral admixture in concrete is only 50-120kg/m3The invention can be used as the inner core of the concrete aggregate with the core-shell structure and can absorb 600kg/m3The hazardous waste has high consumption rate for hazardous solid waste; the core-shell structure concrete aggregate provided by the invention is tightly combined between core shells, so that the cooperative optimization of two interfaces of a three-system is realized, the aggregate can meet the concrete aggregate requirement of structural engineering due to the improvement of the microstructure, the high-value application of solid wastes is realized, and the matching property is excellent.
The invention also provides a preparation method of the concrete aggregate with the core-shell structure, which comprises the following steps:
mixing and curing the preparation raw materials of the kernel to obtain the kernel;
mixing the raw materials for preparing the shell to obtain shell slurry;
and coating the inner core with the shell slurry, and drying to obtain the core-shell structure concrete aggregate.
The preparation method comprises the steps of mixing and curing the preparation raw materials of the inner core to obtain the inner core.
In the preparation raw material of the inner core, before the dangerous solid waste is mixed, the invention preferably further comprises the pretreatment of the dangerous solid waste. In the present invention, the pretreatment preferably includes crushing, drying and pulverizing in this order. In the present invention, the crushing plant is preferably a jaw crusher. In the invention, the drying temperature is preferably 80-105 ℃, and more preferably 90-105 ℃; the time is preferably 4 to 12 hours, and more preferably 5 to 11 hours. In the present invention, the grinding apparatus is preferably a sample mill.
The mixing of the preparation raw materials of the inner core is not particularly limited, and the raw materials of the inner core can be uniformly mixed.
Before the solidification, the invention preferably shapes the core material obtained by mixing the preparation raw materials of the core. In the present invention, the molding is preferably mold molding. In the present invention, the shape of the mold is preferably spherical. In the invention, the diameter of the inner cavity of the die is preferably 5-20 mm, and more preferably 7-18 mm.
In the present invention, the temperature of the curing is preferably 20 ± 1 ℃; the time is preferably 12 to 72 hours, and more preferably 24 to 72 hours.
After the curing, the present invention preferably further comprises demolding to obtain the core.
The shell preparation raw materials are mixed to obtain shell slurry.
In the present invention, the mixing of the raw materials for preparing the housing preferably includes the steps of:
dry-mixing the silicate cement and the silica fume to obtain a first premix;
and mixing the first premix, a polycarboxylic acid water reducing agent and water to obtain the shell slurry.
The method comprises the step of dry mixing the silicate cement and the silica fume to obtain a first premix.
In the invention, the mixing time of the dry mixing is preferably 120-180 s, and more preferably 140-160 s.
After the first premix is obtained, the first premix, the polycarboxylic acid water reducing agent and water are mixed to obtain the shell slurry.
In the invention, the mixing time of the first premix, the polycarboxylic acid water reducing agent and the water is preferably 240-360 s, and more preferably 260-340 s.
After obtaining the core and shell slurry, coating the core with the shell slurry, and drying to obtain the core-shell structure concrete aggregate.
In the present invention, the coating preferably includes: the shell slurry is applied to the surface of the core and the resulting primary aggregate is then tumbled.
In the present invention, the drying temperature is preferably 20 ℃ and the drying time is preferably 24 hours.
The invention also provides the application of the core-shell structure concrete aggregate in the technical scheme or the core-shell structure concrete aggregate prepared by the preparation method in the technical scheme in engineering construction.
The application of the present invention is not particularly limited, and concrete aggregate known to those skilled in the art may be used for the construction of the works.
In the invention, the preparation process of the core-shell structure concrete aggregate does not need to carry out dealkalization or heavy metal removal operation on dangerous solid wastes, and the preparation method has simple process and easy operation.
In order to further illustrate the present invention, the following will describe a concrete aggregate with core-shell structure, its preparation method and application in detail with reference to the examples, but they should not be construed as limiting the scope of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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
Crushing original red mud by using a jaw crusher, drying at 105 ℃ for 6 hours, wherein the red mud has constant weight, and grinding the dried red mud by using a sample preparation crusher to obtain the red mud with the average particle size of less than or equal to 100 mu m;
mixing red mud and water according to the weight ratio of 1000: 240, placing the mixture into a spherical mold with the inner cavity diameter of 5mm, curing the mixture for 24 hours at 25 ℃, and demolding to obtain the inner core;
mixing 52.5-grade portland cement and silica fume (the average particle size is 300nm, and the activity index is more than or equal to 100%) according to a mass ratio of 1000: 200, dry mixing to obtain a first premix; mixing the obtained first premix, a polycarboxylic acid water reducing agent and water according to the ratio of 1200: 30: mixing the components in a mass ratio of 200 to obtain shell slurry;
coating the obtained shell slurry on the surface of an inner core, and rolling the obtained primary aggregate to obtain the core-shell structure concrete aggregate (a physical picture is shown in figure 1), wherein the diameter of the inner core of the obtained core-shell structure concrete aggregate is 5mm, and the thickness of the shell is 1 mm;
SEM test is carried out on the interface of the inner core and the shell in the concrete aggregate with the core-shell structure, the test result is shown in figure 2, and as can be seen from figure 2, the core-shell material of the concrete aggregate with the core-shell structure is tightly combined.
Example 2
The diameter of the core in the core-shell structure concrete aggregate is 5mm, the thickness of the shell is 1.5mm, and the other technical means are the same as those in the embodiment 1, so that the core-shell structure concrete aggregate is obtained.
Example 3
The diameter of the core in the core-shell structure concrete aggregate is 5mm, the thickness of the shell is 2mm, and the other technical means are the same as those in the embodiment 1, so that the core-shell structure concrete aggregate is obtained.
Comparative example 1
Virgin red mud.
Comparative example 2
Only the core prepared in example 1.
Comparative example 3
The diameter of the inner core of the core-shell structure concrete aggregate is 5mm, the thickness of the outer shell is 0.5mm, and the other technical means are the same as those of the embodiment 1, so that the core-shell structure concrete aggregate is obtained.
Test example 1
And (3) carrying out alkali liquor and heavy metal ion leaching tests on the products of the examples 1-3 and the comparative examples 1-3, wherein the test method comprises the following steps: weighing 25g of the products of examples 1-3 and comparative examples 1-3, placing the products in a conical flask, adding 250mL of deionized water, vertically fixing the conical flask on an oscillator, adjusting the frequency to be 110 +/-10 times/min, and oscillating for 6 hours at room temperature; taking down the conical flask, standing for 18h, and filtering and collecting all filtrate in a filtering device provided with a filter membrane; the concentrations of alkali and heavy metals in the solution were measured by atomic absorption spectrophotometry.
The products of examples 1-3 and comparative examples 1-3 were subjected to a single-particle compressive strength test, in which single-particle aggregates with a diameter of 5.5mm were selected and placed in a hydraulic loading type universal testing machine for strength test for compressive strength test with reference to GB/T50081-2002 Standard test method for mechanical Properties of ordinary concrete, and calculation was performed according to a formula, and the average strength value of each type of aggregates tested 20 times was used as the single-particle compressive strength of the aggregates.
The test results are shown in Table 1.
TABLE 1 test results of examples 1-3 and comparative examples 1-3
As can be seen from Table 1, the concrete aggregate with the core-shell structure provided by the invention can effectively reduce the leaching of alkali liquor and heavy metal ions, has high compressive strength, and meets the mechanical property requirements of concrete aggregates in C15-C25 structural engineering.
Example 4
Crushing original lead-zinc tailings by using a jaw crusher, drying at 105 ℃ for 6 hours, wherein the lead-zinc tailings have constant weight, and grinding the dried lead-zinc tailings by using a sample preparation crusher to obtain the lead-zinc tailings with the average particle size of less than or equal to 10 mu m;
mixing lead-zinc tailings, 42.5-grade ordinary portland cement and water according to the weight ratio of 1000: 50: 240, placing the mixture into a spherical mold with the inner cavity diameter of 5mm, curing for 72 hours at 15 ℃, and demolding to obtain the inner core;
mixing 52.5-grade portland cement and silica fume (the average particle size is 300nm, and the activity index is more than or equal to 100%) according to a mass ratio of 1000: 200, dry mixing to obtain a first premix; mixing the obtained first premix, a polycarboxylic acid water reducing agent and water according to the ratio of 1200: 30: mixing the components in a mass ratio of 200 to obtain shell slurry;
and smearing the obtained shell slurry on the surface of the inner core, and rolling the obtained primary aggregate to obtain the concrete aggregate with the core-shell structure, wherein the diameter of the inner core in the obtained concrete aggregate with the core-shell structure is 5mm, and the thickness of the shell is 1 mm.
Example 5
The diameter of the inner core of the core-shell structure concrete aggregate is 5mm, the thickness of the outer shell is 2mm, and the other technical means are the same as those in the embodiment 4, so that the core-shell structure concrete aggregate is obtained.
Comparative example 4
Only the inner core prepared in example 4.
Test example 2
Leachable heavy metal tests and single-particle average compressive strength tests were carried out on examples 4 to 5 and comparative example 4 according to the test method of test example 1, and the test results are shown in table 2.
TABLE 2 test results of examples 4-5 and comparative example 4
As can be seen from Table 2, the concrete aggregate with the core-shell structure provided by the invention can effectively reduce leaching of heavy metal ions, has high compressive strength, and meets the mechanical property requirements of concrete aggregates in C15-C25 structural engineering.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. The core-shell structure concrete aggregate is characterized by comprising an inner core and a shell wrapping the inner core;
the preparation raw materials of the inner core comprise: hazardous solid waste and water;
the shell is prepared from the following raw materials: portland cement, silica fume, a polycarboxylic acid water reducing agent and water.
2. The core-shell structure concrete aggregate according to claim 1, wherein the hazardous solid waste comprises one or more of red mud, tailings and coal gangue.
3. The core-shell structure concrete aggregate according to claim 1, wherein in the preparation raw materials of the inner core, the mass ratio of the dangerous solid waste to water is 1000: (200-400).
4. The core-shell structure concrete aggregate according to claim 1, wherein the preparation raw materials of the inner core further comprise a curing agent; the curing agent comprises ordinary portland cement.
5. The core-shell concrete aggregate according to claim 1 or 2, wherein the average particle size of the hazardous solid waste is less than or equal to 100 μm.
6. The core-shell structure concrete aggregate according to claim 1, wherein in the preparation raw materials of the shell, the mass ratio of the portland cement to the silica fume is 1000: (100-280); the mass ratio of the portland cement to the polycarboxylic acid water reducing agent is 1000: (15-30); the mass ratio of the portland cement to water is 1000: (170-220).
7. The concrete aggregate with the core-shell structure as recited in claim 1 or 6, wherein the silica fume has an average particle size of 300nm and an activity index of not less than 100%.
8. The core-shell structure concrete aggregate according to claim 1, wherein the diameter of the inner core is 5-20 mm; the thickness of shell is 1 ~ 3 mm.
9. The preparation method of the core-shell structure concrete aggregate of any one of claims 1 to 8, which is characterized by comprising the following steps:
mixing and curing the preparation raw materials of the kernel to obtain the kernel;
mixing the raw materials for preparing the shell to obtain shell slurry;
and coating the inner core with the shell slurry, and drying to obtain the core-shell structure concrete aggregate.
10. The core-shell structure concrete aggregate according to any one of claims 1 to 8 or the core-shell structure concrete aggregate obtained by the preparation method according to claim 9 is applied to engineering construction.
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Citations (3)
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|---|---|---|---|---|
| CN110526609A (en) * | 2019-08-31 | 2019-12-03 | 武汉理工大学 | A kind of hud typed sulphoaluminate cement base high-strength light aggregate and preparation method thereof |
| WO2021219058A1 (en) * | 2020-04-29 | 2021-11-04 | 青岛理工大学 | Recycled material floor tile and preparation method therefor |
| CN114014571A (en) * | 2021-12-06 | 2022-02-08 | 桂林理工大学 | Red mud-steel slag high-strength lightweight aggregate with core-shell structure and preparation method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110526609A (en) * | 2019-08-31 | 2019-12-03 | 武汉理工大学 | A kind of hud typed sulphoaluminate cement base high-strength light aggregate and preparation method thereof |
| WO2021219058A1 (en) * | 2020-04-29 | 2021-11-04 | 青岛理工大学 | Recycled material floor tile and preparation method therefor |
| CN114014571A (en) * | 2021-12-06 | 2022-02-08 | 桂林理工大学 | Red mud-steel slag high-strength lightweight aggregate with core-shell structure and preparation method thereof |
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Application publication date: 20220621 |