CN116514509A - Solid waste grouting material for goaf under highway subgrade and preparation method thereof - Google Patents

Solid waste grouting material for goaf under highway subgrade and preparation method thereof Download PDF

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Publication number
CN116514509A
CN116514509A CN202310442693.9A CN202310442693A CN116514509A CN 116514509 A CN116514509 A CN 116514509A CN 202310442693 A CN202310442693 A CN 202310442693A CN 116514509 A CN116514509 A CN 116514509A
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grouting material
solid waste
steel slag
fly ash
highway subgrade
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肖杰
刘财壮
常锦
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Changsha University of Science and Technology
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Changsha University of Science and Technology
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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
    • 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
    • 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
    • C04B18/14—Waste materials; Refuse from metallurgical processes
    • C04B18/141—Slags
    • C04B18/142—Steelmaking slags, converter slags
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C3/00—Foundations for pavings
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C3/00—Foundations for pavings
    • E01C3/003—Foundations for pavings characterised by material or composition used, e.g. waste or recycled material
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C3/00—Foundations for pavings
    • E01C3/04—Foundations produced by soil stabilisation
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
    • E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0075—Uses not provided for elsewhere in C04B2111/00 for road construction
    • 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
    • C04B2111/70—Grouts, e.g. injection mixtures for cables for prestressed concrete
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Materials Engineering (AREA)
  • Architecture (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Agronomy & Crop Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Soil Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • General Engineering & Computer Science (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention relates to the technical field of solid waste recycling, and discloses a solid waste grouting material for a goaf under a highway subgrade and a preparation method thereof, wherein the solid waste comprises fly ash, steel slag and desulfurized gypsum; wherein the steel slag is high-alkalinity steel slag; the particle size distribution of the fly ash, the steel slag and the desulfurized gypsum is respectively 16-45 mu m, 7-27 mu m and 35-6 mu m0 μm; the preparation process of the solid waste grouting material is that the fly ash, the steel slag, the desulfurized gypsum and the water are mixed and stirred at normal temperature, the fluidity of slurry of the grouting material is less than 35S in the whole grouting process, and the compressive strength of the solid waste grouting material after coagulation is more than or equal to 0.6MPa; the total cost of the grouting material is less than or equal to 50 yuan/m 3 . The invention can directly utilize solid waste with a large amount of aperture larger than 200nm, does not need to be broken, and the grouting material prepared according to the formula only meets the mechanical requirement of the grouting material of the goaf under the national highway subgrade.

Description

Solid waste grouting material for goaf under highway subgrade and preparation method thereof
Technical Field
The invention relates to the technical field of solid waste recycling, in particular to a solid waste grouting material for a goaf under a highway subgrade and a preparation method thereof.
Background
The design of the highway in the mining area has a great difficulty that a large number of goafs can be generated after the ore is mined, and the road infrastructure above the goafs is easy to cause disasters such as road collapse, so that traffic safety and transportation in the mining area are seriously damaged, and loss is not estimated. Grouting is an effective means for improving the physical and mechanical properties of rock and soil bodies, is widely applied to the treatment of goafs under roads, and the treatment effect is not only influenced by grouting process and equipment, but also depends on the performance of grouting materials. Cement is the most commonly used grouting material, has the advantages of high strength, good fluidity and the like, but has the advantages of large preparation energy consumption, heavy pollution, high cost, consumption of a large amount of high-quality limestone resources and natural environment destruction. For sustainable development, development of green and environment-friendly grouting materials is needed.
According to the requirements of the specification of the rules of goaf highway design and construction technology (JTGT D31-03-2011), the uniaxial compressive strength of the slurry calculus at the sublevel mining area of the highway subgrade is not less than 0.6MPa. Because the demand of the grouting material of the goaf under the highway subgrade is large, how to develop the grouting material with low cost and working and mechanical properties meeting the goaf under the highway subgrade is still a technical blank neglected in the construction industry at present, and the recycling preparation of the grouting material of the goaf by mass industrial solid wastes is a feasible direction.
The steel slag adopted in the Chinese paper 'the gelation property of the steel slag and the action of the steel slag in the hydration hardening process of the composite cementing material' mostly has the grain diameter of less than 6 mu m or more than 60 mu m, and the steel slag is compounded with fly ash and desulfurized gypsum to obtain the cementing system with the compressive strength as high as 39.6MPa; the reaction mechanism and application research of a steel slag-fly ash-desulfurized gypsum composite gel system in Chinese paper adopts a supersonic steam crushing mechanism to crush fly ash, steel slag and desulfurized gypsum into particles with micron-sized particle diameters, so that the mechanical strength of the obtained gel material is greatly improved to 44.2MPa, but the conditions of the raw materials are very critical, such as components and particle diameters, and the morphology components of solid waste materials are different, the mechanical effects of the prepared materials are different, particularly the fly ash, steel slag and desulfurized gypsum with the particle diameters of tens of microns, which are produced in large quantity, are loose in combination due to the fact that the particles with the large specific surface area are more than 200nm, the effect of rapidly deteriorating the mechanical properties cannot be directly selected as building materials, the crushing treatment is needed, and the toxic impurities which are stabilized in the solid waste are often released again in the crushing process, so that secondary pollution is caused; according to the requirements of low cost, simple process and stable and environment-friendly solid waste materials of the goaf under the highway subgrade, the inherent technical contradiction in the prior art cannot meet the requirements of the method for preparing the grouting materials by effectively treating most of fly ash, steel slag and desulfurized gypsum solid waste materials.
Disclosure of Invention
Aiming at the technical blank that the gel material cannot be prepared by directly treating and applying the non-activated solid waste materials in the prior art, and the goaf grouting material with low cost and performance meeting the construction requirements is prepared, the invention provides the solid waste grouting material for the goaf under the highway subgrade, which can directly utilize the solid waste material with a large amount of apertures larger than 200nm without activation, and the grouting material prepared according to the solid waste raw material formula only directly meets the mechanical and working performance requirements of the goaf grouting material under the national highway subgrade; the invention also provides a preparation method of the solid waste grouting material for the goaf under the highway subgrade, which can directly utilize a large amount of solid waste materials with the particle size of more than 200nm, does not need special treatment, and only meets the mechanical requirement of the grouting material of the goaf under the national highway subgrade directly.
The following technical scheme is realized:
solid waste grouting material for goaf under highway subgrade, wherein the solid waste comprises fly ashSteel slag and desulfurized gypsum; wherein the steel slag is high-alkalinity steel slag; the particle size distribution of the fly ash, the steel slag and the desulfurized gypsum is respectively 16-45 mu m, 7-27 mu m and 35-60 mu m; the preparation process of the solid waste grouting material is that the fly ash, the steel slag, the desulfurized gypsum and the water are mixed and stirred at normal temperature, the fluidity of slurry of the grouting material is less than 35S in the whole grouting process, and the compressive strength of the solid waste grouting material after coagulation is more than or equal to 0.6MPa; the total cost of the grouting material is less than or equal to 50 yuan/m 3 。
The particle size distribution of the fly ash, the steel slag and the desulfurized gypsum is 16-45 mu m, 7-27 mu m and 35-60 mu m respectively, which are the most common in solid waste, the solid waste price in the particle size range is the cheapest, the ratio of the maximum particle size to the minimum particle size is less than 3 as known from the particle size distribution of raw materials, even if the ratio of the maximum particle size of the desulfurized gypsum to the minimum particle size of the steel slag is also less than 9, the effect that hydration reaction is generated between the large particles and the small particles to strengthen the density and the mechanical effect is weak, and the raw material particles contain a large number of large micropores above 200nm, which are unfavorable for the connection of the raw material particles through the hydration reaction, but severely reduce the mechanical property of the grouting material. Under the general condition, the raw materials are crushed, the particle size reaches a plurality of micrometers, the oversized micropores are reduced, the specific surface area is enlarged by small particle size, or part of the raw materials are crushed, the small-particle-size raw materials are embedded into the large-particle-size raw materials, and the micropores are filled to improve the mechanical effect, and even the requirements of the grouting material of the goaf under the highway subgrade on low cost, stability and environmental protection are met, the current general grinding delivery cost is 40 yuan/ton, in fact, the fly ash production cost in the raw materials is 0-300 yuan/ton, wherein the circulating fluidized bed boiler desulfurized fly ash, namely CFB ash, is generally 0 yuan/ton, the production delivery cost of desulfurized gypsum is generally 0 yuan/ton, the solid waste treatment is also complemented, the production delivery cost of steel slag is 65-70 yuan/ton, and meanwhile, the fluidity of the grouting material is required to be kept below 35S, so that the grouting material is conveniently injected into the underground goaf. Raw material particles with large particle size are low in hydration degree and not tightly combined with each other, the fluidity of the mixed material according to random proportion is often larger than 35S, the mechanical requirement of grouting materials cannot be met, and excessive added materials such as a glidant, a water reducer and an exciting agent have the effect of improving performance to a certain extent, but extra cost and construction risk are increased. Under the restriction of three severe technical and economic indexes of cost, compressive strength and fluidity and the property of the material, in the experimental preparation process of the grouting material, the working mechanical property index of the obtained grouting material is difficult to be stabilized within the standard requirement range, and the difficult problem initiates a serious challenge to the existing grouting preparation technology, and a simple and convenient preparation method with low cost is needed. Therefore, according to the characteristics of the raw materials, the most suitable mixing ratio among the raw materials is found out by utilizing a synergistic principle, so that the working mechanical property of the prepared grouting material for the goaf under the roadbed can reach the standard requirement.
Preferably, the specific surface area of the fly ash is 300-500 m 2 Per kg, the specific surface area of the steel slag is 551-700 m 2 Per kg, the specific surface area of the desulfurized gypsum is 100-250 m 2 /kg。
Preferably, the fly ash is circulating fluidized bed boiler desulfurization fly ash, and is called CFB ash for short.
Preferably, the CFB ash formation temperature is 800-1000 ℃.
The circulating fluidized bed boiler desulfurized fly ash is called CFB ash for short, is fly ash generated by combustion of a circulating fluidized bed boiler of a thermal power plant, and has larger difference with the fly ash in aspects of particle morphology, forming temperature, chemical composition and the like: the forming temperature of CFB boiler desulfurization ash is only 800-1000 ℃, wherein CFB ash formed at 900 ℃ is common, so that glass phase is difficult to form, glass beads cannot be formed in particles, amorphous particles are mainly formed, the forming temperature of common fly ash is 1400-1500 ℃, and the particle morphology of the common fly ash is mainly round glass beads; the annual discharge amount of CFB ash is about 1.2 hundred million tons, the current stock amount is about 7 hundred million tons, the comprehensive utilization rate is less than 20 percent, and the treatment is mainly carried out by piling, thereby causing serious environmental pollution and huge social influence, and the chemical components of the CFB ash mainly contain SiO 2 、Al 2 O 3 Has a certain volcanic ash activity.
The preparation method of the solid waste grouting material for preparing the roadbed of the goaf underlying the highway roadbed comprises the steps of mixing and stirring fly ash, steel slag and desulfurized gypsum according to the mass ratio of 45-50:40-50:5 to form a solid phase I, and mixing and stirring the solid phase I and water according to the mass ratio of 1.3-1.4:1 to form the grouting material.
Preferably, the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase II according to the mass ratio of 40-43:52-57:5, and then the solid phase II and water are mixed and stirred into a grouting material according to the mass ratio of 1.3-1.5:1.
Preferably, the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase III according to the mass ratio of 20-25:65-75:5, and then the solid phase III and water are mixed and stirred into a grouting material according to the mass ratio of 1.3-1.6:1.
The raw materials are mixed into a solid phase according to different proportions, the solid phase is mixed with water to form a grouting material, the fluidity and the mechanical strength of the obtained grouting material are quite different, the range of constraint conditions is easily exceeded, the function of the grouting material is lost to become waste products, the improper proportion can cause the recycling failure of solid waste, secondary solid waste is formed, pollution and the waste of storage occupied area are caused, and only the mixing ratio of the raw materials and the solid-water ratio are strictly limited, the grouting material with low cost, the fluidity of less than or equal to 35S and the mechanical strength of more than or equal to 0.6MPa can be produced.
The application of the solid waste grouting material for the goaf under the highway subgrade as the grouting material for the goaf under the highway subgrade, the grouting material is poured into the goaf under the highway subgrade, the grouting material can be hardened and molded by 14d, and the stone body strength of the 28d grouting material can meet the construction requirement and far exceeds the maintenance age requirement of 180d in the specification.
The invention has the beneficial effects that:
(1) The inherent characteristics of fly ash, steel slag and desulfurized gypsum in the solid waste with low performance are fully exerted by the excellent mixing proportion, the interaction between raw materials is enhanced, the hydration reaction is accelerated as much as possible, the mechanical strength of the grouting material is improved, and the index of the grouting material for the highway subgrade in the goaf under the highway subgrade is reached.
(2) Only the fly ash, the steel slag and the desulfurized gypsum in the solid waste are adopted as solid phases, no additional additive is needed, the grinding technology is not adopted to reduce the particle size of raw materials, all the cost and the process are pressed in a very simple state, but the performance of the grouting material still reaches relevant indexes.
(3) The fluidity of the grouting material is controlled by the excellent mixture ratio and solid-water ratio, so that the fluidity of the grouting material is required to be kept at an index smaller than or equal to 35S, the raw materials are convenient to mix and the goaf grouting is convenient, and the construction process is smooth.
(4) The method finds a new value generation way for CFB ash and desulfurized gypsum with low quality and zero market price, effectively promotes the recycling of solid wastes, strengthens the utilization of wastes and promotes the environmental purification.
(5) A method for quickly preparing the grouting material of the goaf under the highway subgrade at low cost is found, and the stability of the underground goaf is effectively promoted.
Drawings
Fig. 1 is a 10000-fold SEM image of a grouting material.
Fig. 2 is a 3000 x SEM image of the grouting material.
Fig. 3 is an XRD pattern of the grouting material.
Fig. 4 is an SEM image of raw materials CFB ash, steel slag, and desulfurized gypsum.
Fig. 5 shows particle size distribution and volume distribution of raw materials CFB ash, steel slag, and desulfurized gypsum.
Fig. 6 is a graph of the water evolution rate experiment and test piece maintenance during the preparation process.
Fig. 7 shows the density of the resulting slurry at different raw material ratios.
FIG. 8 shows the fluidity of the resulting slurry at different raw material ratios.
FIG. 9 shows the water separation rate of the resulting slurry at different raw material ratios.
Figure 10 shows the calculus rates of the resulting slurries at different raw material ratios.
Fig. 11 shows the 28d compressive strength of the resulting slurries at different raw material ratios.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following examples; it should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the invention; in the examples, all means used are conventional in the art unless otherwise specified; the terms "comprises," "comprising," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion; for example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus; in addition, technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other; the experimental raw materials used in the examples and comparative examples of the present invention are all commercially available products.
The raw materials used in examples 1 to 4 and comparative examples 1 to 5 were as follows in chemical composition:
raw materials Al 2 O 3 SiO 2 CaO Fe 2 O 3 K 2 O MgO Na 2 O SO 2 CaO
Fly ash 31.73 49.09 4.32 8.55 0.92 0.73 0.26 2.80 0.10
Steel slag 5.5 17.2 48.3 12.2 - 5.6 - 0.64 0.66
Desulfurized gypsum - 1.1 46.7 - - - - 49.6 -
Particle size distribution of raw materials used in examples 1 to 4 and comparative examples 1 to 5
Example 1
The preparation method of the solid waste grouting material for the goaf under the highway subgrade comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum according to the mass ratio of 20:75:5 into a solid phase, mixing and stirring solid phase and water according to the mass ratio of 1.6:1 into the grouting material, wherein the total cost of raw materials is 48.75 yuan/ton.
Example 2
The preparation method of the solid waste grouting material for the goaf under the highway subgrade comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum according to the mass ratio of 237:2:5 into a solid phase, mixing and stirring solid phase and water according to the mass ratio of 1.3:1 into the grouting material, wherein the total cost of raw materials is 46.8 yuan/ton.
Example 3
The preparation method of the solid waste grouting material for the goaf under the highway subgrade comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum into a solid phase according to the mass ratio of 40:55:5, mixing and stirring solid phase and water into the grouting material according to the mass ratio of 1.5:1, wherein the total cost of raw materials is 35.75 yuan/ton.
Example 4
The preparation method of the solid waste grouting material for the goaf under the highway subgrade comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum according to the mass ratio of 50:45:5 into a solid phase, mixing and stirring solid phase and water according to the mass ratio of 1.4:1 into the grouting material, wherein the total cost of raw materials is 29.25 yuan/ton.
Comparative example 1
The preparation method of the solid waste grouting material comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum into a solid phase according to the mass ratio of 40:55:5, mixing and stirring a solid phase and water according to the mass ratio of 1.6:1 to obtain the grouting material, wherein the total cost of raw materials is 35.75 yuan/ton.
Comparative example 2
The preparation method of the solid waste grouting material comprises the steps of mixing and stirring CFB ash, steel slag and desulfurized gypsum into a solid phase according to the mass ratio of 50:45:5, mixing and stirring a solid phase and water according to the mass ratio of 1.6:1 to obtain the grouting material, wherein the total cost of raw materials is 29.25 yuan/ton.
Comparative example 3
A preparation method of a solid waste grouting material is characterized in that CFB ash, steel slag and desulfurized gypsum are mixed and stirred into a solid phase according to the mass ratio of 60:35:5, and then the solid phase and water are mixed and stirred into the grouting material according to the mass ratio of 1.6:1, and the total cost of raw materials is 22.75 yuan/ton.
Comparative example 4
A preparation method of a solid waste grouting material is characterized in that CFB ash, steel slag and desulfurized gypsum are mixed and stirred into a solid phase according to the mass ratio of 60:35:5, and then the solid phase and water are mixed and stirred into the grouting material according to the mass ratio of 1.3:1, and the total cost of raw materials is 22.75 yuan/ton.
Comparative example 5
A preparation method of a solid waste grouting material is characterized in that CFB ash, steel slag and desulfurized gypsum are mixed and stirred into a solid phase according to the mass ratio of 80:15:5, and then the solid phase and water are mixed and stirred into the grouting material according to the mass ratio of 1.3:1, wherein the total cost of raw materials is 9.75 yuan/ton.
Comparative example 6
The preparation method of the solid waste grouting material is characterized in that the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase according to the mass ratio of 20:70:10, and then the solid phase and the water are mixed and stirred into the grouting material according to the mass ratio of 1.5:1, and the total cost of raw materials is 91.5 yuan/ton.
Detection method
SEM: breaking a broken test piece in the compressive strength, selecting fragments at the central part to be placed in absolute ethyl alcohol to terminate hydration, placing the fragments in a 60 ℃ oven to be baked to constant weight before testing, selecting small blocks with flat surfaces, and adopting MiRA4 LMH eds of the Czech TESCAN company; SEM experiments were performed on One Max 50 scanning electron microscope.
XRD: the rest fragments are sieved by an agate mortar, and then the mineral components are measured by an Empyren X-ray diffractometer of PANalytical company of Netherlands, wherein the scanning range 2 theta is 5-80 degrees, and the scanning speed is 5 degrees/min.
Slurry density test: referring to the specification of basic performance test method of building mortar (JGJ/T70-2009), the density of fresh slurry is measured according to the mass and volume by adopting a capacity bucket method.
Water extraction rate test: according to the standard of Highway engineering Cement and Cement concrete test procedure (JTG 3420-2020), 950mL of slurry is slowly and uniformly poured into a 1000mL measuring cylinder after fresh grouting material is uniformly stirred, and the initial scale a is recorded after standing for 1min 1 After 3h of standing, measuring the high strength a of the lower precipitated colloid surface 2 Calculate the water separation rate = (a) 1 -a 2 )/a 1 *100％。
Calculus rate test: and (3) determining the calculus rate of the grouting material by referring to a gel rate test in technical Specification for highway bridge and culvert construction (JTG/TF 50-2011), respectively taking 450mL of slurry of different proportions, injecting the slurry into a 500mL measuring cylinder, and reading the calculus volume in the measuring cylinder after 24 hours, wherein the ratio of the calculus rate to the volume is the calculus rate.
Flow test: and (3) carrying out slurry fluidity test by using an inverted cone metallograph according to the specification of the test procedure of highway engineering cement and cement concrete (JTG 3420-2020).
Uniaxial compressive strength test: test pieces are manufactured and the compressive strength is tested according to highway engineering cement and cement concrete test procedure (JTG 3420-2020), grouting materials are poured into a cube test mould, after demoulding, the test pieces are put into a curing chamber with the temperature of about 20 ℃ and the humidity of about 95% for curing for 14d and 28d, and then the strength of the test pieces is measured.
Table 1 test data of examples 1 to 4 and comparative examples 1 to 5
As shown in Table 1, the above examples 1 to 4 all reached the standard under the severe constraint that the fluidity was 1 to 35S, the compressive strength was 0.6MPa or more, and the cost was as low as possible, wherein the mass ratio of the CFB ash, the steel slag and the desulfurized gypsum in example 1 was 20:75:5, when the solid-water ratio is between 1.3 and 1.6, as shown in fig. 11, the compressive strength is in direct proportion to the relative solid phase, as shown in fig. 8, the fluidity is inversely proportional to the relative solid phase, and when the solid-water ratio is not in the protection range, according to the data of comparative examples 1 to 5, the fluidity is obviously increased beyond 35S and the grouting cannot be effectively performed, the grouting material is used as the function of the sublevel goaf of the highway subgrade, while comparative example 6 adopts the secondary fly ash with the production cost of 240 yuan/ton, and the mechanical property is similar to that of example 1, but the price is too high, the advantage of low cost is lost, and even the high-price fly ash formed at 1400-1500 ℃ cannot fully perform the performance advantage under the same extremely simple preparation process, and the performance of the grouting material is improved.
TABLE 2 slurry density data obtained from different raw material ratios and Water-to-solid ratios
TABLE 3 data of slurry water separation rate obtained from different raw material ratios and water-solid ratios
Table 4 data on slurry stone rates obtained from different raw material ratios and water-to-solid ratios
TABLE 5 slurry flow data obtained with different raw material ratios and water-to-solid ratios
Table 6 compressive strength of slurry 14d obtained by different raw material ratios and water-solid ratios
Table 7 data of 28d compressive strength of slurries obtained from different raw material ratios and water-to-solid ratios
Tables 2 to 7 show the original performance data of the slurries obtained by different raw material ratios and water-solid ratios, and as seen in connection with fig. 7 to 11, the compressive strength increases with the increase of the relative solid phase content, and the fluidity increases with the increase of the relative water content, but when the raw material ratio and the solid-water ratio are out of the protection range, the fluidity increases too fast, exceeding the constraint condition that the fluidity is less than or equal to 35S, the calculi rates obtained by all the ratios and the water-solid ratios are similar, and the early strength of the obtained needle-like ettringite cement has a beneficial effect; the densities obtained by all the proportions and the water-solid ratio are similar; and the mixture ratio of CFB ash, steel slag and desulfurized gypsum is 20:75:5, which is mainly related to the relative amount of CFB ash, the more the relative content of CFB ash is, the smaller the water-separating amount is, the highest stability is, the stability of the slurry is influenced by the free sedimentation speed of raw material particles in the slurry, the faster the sedimentation speed of the raw material particles is, the worse the stability is, the larger the water-separating rate is, and the factors influencing the free sedimentation speed are mainly the particle size of the raw material particles, the particle density and the viscosity of the slurry, compared with steel slag, although the particle size of the CFB ash is larger, the particle surface is rough due to the small density, the open pores are more, more free water can be absorbed, the viscosity of the slurry is improved, and the water-separating rate is reduced; FIGS. 1 and 2 are SEM electron micrographs of the grouting material amplified 10000 times and 3000 times, in which it is seen that the C-S-H bonds formed after the hydration reaction coexist with the mayenite, and at 14d, the grouting material has many surface pores and large-area holes and gaps, which indicates that the hydration products are few at this time, the raw material particles are not firmly connected, the structure is not compact, the uniaxial compressive strength is low, and at 28d, the grouting material has more compact structure, the large-area holes and gaps are reduced, the uniaxial compressive strength is increased, and A in the graph 1～5 B 1～5 C 1～5 D 1～5 The marks corresponding to different raw material ratios and water-solid ratios are as follows:
table 8 different proportioning sign correspondence information in fig. 1 and 2
Table 9 the label correspondence information of 14d and 28d in fig. 1 to 3
B as seen in combination with FIGS. 1-2 and 11 4～5 、C 3～5 、D 2～5 The 14D compressive strength of 9 groups meets the rule of goaf highway design and construction technology rule (JTGT D31-0302-11) that the stone body of the goaf under the highway subgrade should not be less than 0.6MPa, and the stone body is increased to 15 groups when 28D, only A 1 、A 2 、B 1 And C 1 The total 4 groups do not meet the requirements, the maximum value is 1.46MPa, when the water-solid ratio is fixed, the compressive strength of the stone body is increased along with the decrease of the CFB ash doping amount, and when the CFB ash doping amount is 50% or less, the 28d compressive strength of each water-solid ratio is all required by east-line specification; when the CFB ash mixing amount is fixed, the compressive strength of the stone body is gradually increased along with the reduction of the water-solid ratio, and when the water-solid ratio is 1:1.6, the stone body is divided into D 1 The 14d compressive strength and the 28d compressive strength of other test pieces meet the requirements except that the test pieces cannot be normally molded, so that the water-solid ratio is an important factor influencing the compressive strength of the stone body, and the higher the water-solid ratio is, the lower the solid content of CFB ash and steel slag is, the lower the compactness of the test piece is, the lower the active ingredient is, the fewer hydration reaction organisms are, and the more free water is in the test piece, and the more pores are in the test piece; at 14d in FIG. 2, B 2 、B 3 、C 3 The surface pores of the slurry are more, and gaps with large-area holes are formed, so that the slurry has the advantages of less hydration products, weak connection among raw material particles, loose structure, low uniaxial compressive strength and more compact and large slurry structure at 28dArea holes and gaps are reduced, uniaxial compressive strength is increased, and comparative analysis is carried out by 28dB 2 、B 3 、B 5 And A is a 3 、B 3 、C 3 The test results of (1) find that the same water-solid ratio, the same CFB ash mixing amount, the corresponding hydration product quantity, the more compact structure, the gradually reduced pores and gaps, the same macroscopic mechanical strength change rule and XRD analysis result are consistent; as shown in FIG. 1, the types of hydration products are substantially the same, mainly ettringite and C-S-H gel, ca (OH), as can be seen from FIG. 1, by amplifying the sample to 10000 times 2 The quantity is very small, and at 14d, B is approximately the same as the XRD result 2 、B 3 The quantity of the C-S-H gel and the acicular ettringite on the surface is small, and the lap joint among the particles is not tight; c (C) 3 Although there is a small amount of cracks, there is relatively more C-S-H gel and ettringite crystal filling, the structure is more compact, at 28d, B 2 、B 3 And C 3 Increased hydration products and further reduced fissures, B 2 The amount of the ettringite crystal is increased and coarser, flocculent C-S-H gel is distributed in a scattered way, and the overall structure is higher than that of B of 14d 2 Is denser; b (B) 3 Compared with B 2 The gel has C-S-H gel groups, and is mutually overlapped with fine ettringite crystals, so that the internal structure is more complete; c (C) 3 More C-S-H gel groups are generated, and the calcium vanadate crystals are wrapped to fill the pores, so that the structure is compact, and the compressive strength is increased; comparative analysis of B with the same Water-to-solid ratio (1:1.4) and different CFB Ash contents 2 (60％)，B 3 (50％)，B 5 (20%) it was found that as the amount of steel slag added was increased, the flocculent C-S-H gel was gradually increased, B 5 The particle surface is covered with large flocculent C-S-H gel, and the well developed ettringite crystal is wrapped to fill the particle pores, so that B 5 Ratio B 2 、B 3 The density is higher, and the strength is also higher; comparative analysis of the same CFB Ash content (50%) A with different Water-to-solid ratios 3 (1∶1.3)、B 3 (1∶1.4)、C 3 (1:1.5), the number of the ettringite and the C-S-H gel is increased along with the reduction of the water-solid ratio, the pores are reduced, and the test piece is more compact; as can be seen from the combination of XRD and SEM microscopic test results, the water-solid content is reducedThe method can reduce the mixing amount of CFB ash or increase the mixing amount of steel slag, increase the maintenance period of the test piece, increase the amount of hydration products C-S-H gel and ettringite, and enable the test piece to be more compact, thereby improving the compressive strength of the test piece and conforming to the development rule of macroscopic mechanical properties.
XRD of FIG. 3 also showed Ca (OH) formation within 14 days and 28 days 2 And ettringite, 14d, B 2 、B 3 、C 3 The peak value of the gypsum is B from big to small 2 ＞B 3 ＞C 3 The peak value of ettringite is C from large to small 3 ＞B 3 ＞B 2 B when the age is increased to 28d 2 、B 3 And C 3 The calcium vanadium Dan Fengzhi of (2) is increased, the gypsum peak value is reduced, and the compressive strength is respectively increased by 0.17, 0.15 and 0.17MPa; a with the same CFB ash mixing amount and different water-solid ratios of 28d 3 、B 3 、C 3 As the water-solid ratio is reduced, the gypsum peak value is gradually reduced, the water-solid ratio is the same, and the CFB ash mixing amount is different in 28d age 2 、B 3 、B 5 As the CFB ash dosage decreases, the gypsum peak decreases, the calcium vanadium Dan Fengzhi increases, and the quartz peak gradually decreases. As is evident from the above, the gypsum gradually decreases with the progress of the hydration reaction, and the larger the peak of the hydration product ettringite is, which is caused by the high quartz content (49.09%) in CFB ash, and the raw material has been studied to contain more active SiO 2 、CaO、C 2 S、C 3 S and calcium sulfate, C-S-H are produced with high probability, C-S-H is amorphous gel, and cannot be directly displayed in an XRD pattern, and a large number of humps are possibly formed between 30 and 40 degrees in the pattern; for grouting materials, siO in CFB ash 2 With Al 2 O 3 The content is 80.82%, the CaO is only 4.32%, the larger the mixing amount is, the Ca in the slurry is 2+ The lower the ion content, the lower the hydration reaction speed and the hydration products such as C-S-H, ettringite and the like are caused; steel slag (also containing a small amount of active C) with higher CaO content (48.3%) 2 S、C 3 S and other mineral components) to continuously hydrate Ca 2+ 、OH - The plasma active ions raise the alkalinity of the slurry and provide a proper hydration alkaline environment; meanwhile, the desulfurized gypsum has large solubility and can quickly play an excitation roleReleasing a large amount of Ca 2+ The ions and sulfate ions accelerate the generation of C-S-H and the ettringite, and the fly ash generates volcanic ash reaction under the proper hydration environment, so that silicon oxygen tetrahedron and aluminum oxygen tetrahedron can be released to react with Ca 2+ The ions are combined to generate C-S-H and the ettringite, so that the strength of the calculi body is improved.
Figures 4 and 5 show the particle and particle size distribution of the raw materials, the particle size distribution of the raw materials is 16-45 μm, 7-27 μm, 35-60 μm, which is unfavorable for hydration reaction, so that the engineering standard of the grouting material can be reached only with proper raw material proportion under the condition of no alkali excitation.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention, and it is intended to cover in the appended claims the protection of this invention as defined by the claims.

Claims (8)

1. The solid waste grouting material for the goaf under the highway subgrade is characterized in that the solid waste comprises fly ash, steel slag and desulfurized gypsum; wherein the steel slag is high-alkalinity steel slag; the particle size distribution of the fly ash, the steel slag and the desulfurized gypsum is respectively 16-45 mu m, 7-27 mu m and 35-60 mu m; the preparation process of the solid waste grouting material is that the fly ash, the steel slag, the desulfurized gypsum and the water are mixed and stirred at normal temperature, the fluidity of slurry of the grouting material is less than 35S in the whole grouting process, and the compressive strength of the solid waste grouting material after coagulation is more than or equal to 0.6MPa; the total cost of the grouting material is less than or equal to 50 yuan/m 3 。
2. The solid waste grouting material for the goaf under the highway subgrade according to claim 1, wherein the specific surface area of the fly ash is 300-500 m 2 Per kg, the specific surface area of the steel slag is 551-700 m 2 Per kg, the specific surface area of the desulfurized gypsum is 100-250 m 2 /kg。
3. A solid waste grouting material for a goaf underlying a highway subgrade according to claim 1, wherein said fly ash is circulating fluidized bed boiler desulfurized fly ash.
4. A solid waste grouting material for a goaf under a highway subgrade according to claim 3, wherein the circulating fluidized bed boiler desulfurized fly ash has a formation temperature of 800-1000 ℃.
5. The method for preparing the solid waste grouting material for the goaf under the highway subgrade according to any one of claims 1 to 4, which is characterized in that the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase I according to a mass ratio of 45-50:40-50:5, and then the solid phase I and water are mixed and stirred into the grouting material according to a mass ratio of 1.3-1.4:1.
6. The method for preparing the solid waste grouting material for the goaf under the highway subgrade, which is characterized in that the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase II according to the mass ratio of 40-43:52-57:5, and then the solid phase II and water are mixed and stirred into the grouting material according to the mass ratio of 1.3-1.5:1.
7. The method for preparing the solid waste grouting material for the goaf under the highway subgrade, which is characterized in that the fly ash, the steel slag and the desulfurized gypsum are mixed and stirred into a solid phase III according to the mass ratio of 20-25:65-75:5, and then the solid phase III and water are mixed and stirred into the grouting material according to the mass ratio of 1.3-1.6:1.
8. The use of a solid waste grouting material for an under-highway subgrade goaf as claimed in any one of claims 1 to 7, wherein the grouting material is poured into the under-highway subgrade goaf and hardened and formed for 14 to 28 days.
CN202310442693.9A 2023-04-23 2023-04-23 Solid waste grouting material for goaf under highway subgrade and preparation method thereof Pending CN116514509A (en)

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