CN109626925B - Preparation method of phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement - Google Patents
Preparation method of phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement Download PDFInfo
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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
- C04B28/16—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 anhydrite, e.g. Keene's cement
- C04B28/165—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 anhydrite, e.g. Keene's cement containing synthetic anhydrite
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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
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
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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
- C04B11/00—Calcium sulfate cements
- C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/0075—Uses not provided for elsewhere in C04B2111/00 for road construction
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/27—Water resistance, i.e. waterproof or water-repellent materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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Abstract
The invention provides a preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement, and relates to the field of roadbed materials. Firstly, calcining phosphogypsum with the free water content of 7-20% at high temperature to obtain a high-temperature product, then preparing a waterproof agent slurry obtained by mixing a silane coupling agent, polyvinyl alcohol and hot water, finally mixing the prepared high-temperature product, the waterproof agent slurry and Portland cement according to the mass percentage of 85-93%, 3.5-5% and 3-10%, and uniformly stirring to obtain the phosphogypsum roadbed material; in portland cement, C3The mass fraction of the mineral A in the Portland cement is 2-5%, and a mineral admixture containing aluminosilicate cannot be doped in the Portland cement. The phosphogypsum roadbed material prepared by the method has the advantages of good strength, water stability and volume stability, simple preparation process, low production cost and wide raw material source.
Description
Technical Field
The invention relates to the field of roadbed materials, in particular to a preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement.
Background
Roadbed material refers to a road construction material which is located under a road base layer, bears the action of vehicle loads transmitted from the road surface during application, and resists the action of erosion caused by various environmental factors (freeze thawing, drying, water solution infiltration and the like). Roadbed materials have good strength, water stability and durability, and traditional roadbed materials comprise natural resources such as pebbles, broken stones, gravels, clay and the like. Along with the construction of large-scale traffic facilities in China, natural resources such as sand and stones are nearly exhausted, and the use of clay can destroy vegetation and planting land, so that the search for a substitute material of a traditional roadbed material is urgent from the aspects of resource protection, ecological protection and environmental protection.
The phosphogypsum is a byproduct in the chemical process of extracting phosphoric acid by using a sulfuric acid method in the phosphorus chemical process, and the main component of the phosphogypsum is dihydrate gypsum. Besides the main component, the phosphogypsum also contains H+、SiO2、Al2O3、Fe2O3MgO, water-soluble P2O5And F-And impurities are added so that the pH value is 1.5-4.5 and the color is light yellow to grey brown. China is a large country of phosphorus chemical industry worldwide, and the stockpiling amount of phosphogypsum in China is about 2.5 hundred million tons, the annual emission amount is about 0.2 hundred million tons, the annual utilization rate is only about 20 percent, and the stockpiling amount is gradually increased. Collected in ChinaThe phosphogypsum is discharged by a wet discharging method, the free water content of the newly produced phosphogypsum is more than 15 percent, and the free water content of the stockpiled phosphogypsum which is balanced with the humidity of the natural environment is less than 10 percent under a long-time stacking state. Compared with newly produced phosphogypsum, part of redundant water in the stockpiled phosphogypsum is evaporated, and part of the redundant water permeates into soil at the lower part of a yard, and the permeated water carries acid radicals, soluble phosphate radicals and soluble fluoride ions, so that underground water pollution is caused, and the health and survival of plants, organisms and human beings are harmed, therefore, the method should be avoided at utmost.
Dialectically, phosphogypsum, which forms a great pressure on ecology and environment, can also become a valuable resource if it can be reasonably utilized. Under the condition of proper water content, the phosphogypsum block formed by heavy compaction has the uniaxial compressive strength of more than 1MPa, and the strength meets the requirement that a secondary and below-secondary stable material is used as a pavement base layer, thereby illustrating the potential of the phosphogypsum used as a pavement base material.
It should be noted that the main constituent material of phosphogypsum is dihydrate gypsum, which has high water solubility. Under normal temperature environment, the solubility of the dihydrate gypsum is about 2.1g/L, so the water resistance of the phosphogypsum compact is poor, which limits the feasibility of the phosphogypsum used as a roadbed material. If the phosphogypsum material can be improved properly, and the strength, the water stability and the volume stability of the phosphogypsum material are improved, the phosphogypsum can become an available roadbed material, even become a roadbed preparation material of first-class highways and expressways.
Aiming at the improvement of the strength, water stability and volume stability of the phosphogypsum roadbed material, some researchers search: the research results of Zhangying et al show that after quicklime is used as a stabilizer, a mixture of phosphogypsum and fly ash (the quicklime: the phosphogypsum: the fly ash is 8:52:40) undergoes a hydration reaction to form a solidified body, and the strength of the solidified body can meet the strength requirement of a second-level highway second-ash roadbed material (Zhang Ying, Tonghuang, Shenwei, and the like; research on waste gypsum, pulverized coal ash and lime binder [ J ]. building materials world, 2009,30(5): 45-47.); zhoufuchao et al studied the relationship between the composition and strength of the phosphogypsum-cement-fly ash-lime system, and the research results showed that the hydration of cement improved the strength of the system, and the strength of the system increased first and then decreased with the increase of the mixing amount of phosphogypsum (Zhoufuchao, Shizongli. experimental study of phosphogypsum roadbed materials [ J ]. Chinese building materials science and technology, 2014,23(4): 49-52.). Xuzeyou and the like research feasibility of a mixture prepared from quick lime, coal ash and phosphogypsum (quick lime, coal ash and phosphogypsum are 14:3:83) and used as a limestone aggregate gap filling material, and research results show that: when the volume of the mixture is equal to the volume of the voids of the aggregate, the optimal dry density and compression resistance can be obtained, and meanwhile, the water-swelling performance of the mixture meets the requirement of roadbed materials (Xuezyou, Lottinghao, Wang Yibo. research on the performance test of the modified phosphogypsum mixed crushed stone for roads [ J ]. proceedings of the institute of industry and academy of the State, 2008,21(s1): 61-64.); the application of phosphogypsum in roadbed preparation is researched by Dongbangsheng and the like, and the research result shows that: phosphogypsum with a suitable water content, after suitable compaction, gives phosphogypsum blocks with a CBR value suitable for roadbed applications, but it is also recognised that roadbeds made with phosphogypsum cannot be flooded for long periods of time, otherwise serious strength losses result (dungheng, ling, schwaren. application of industrial waste phosphogypsum in roadbed engineering [ J ] huadong highway, 2001(3): 55-58.).
From the existing research results, the research idea of using the phosphogypsum as a roadbed material is to utilize hydraulic cementing materials (cement, fly ash) and/or air-hardening cementing materials (quick lime and hydrated lime) to bond phosphogypsum particles so as to improve the strength and the permeation resistance of a compacted body, so that a composite system has the potential of being used as a roadbed material. However, in the existing research, only phosphogypsum is used as an inert material, the cementing strength of the phosphogypsum is not utilized and exerted, and meanwhile, the long-term volume stability of the phosphogypsum roadbed material is not considered, because in terms of mechanism, the phosphogypsum and a calcium aluminate component in a cementing material generate slow hydration reaction to generate a hydration product-ettringite with expansion capability, so that the roadbed material is subjected to expansion damage in the service process, and the engineering quality and traffic safety are damaged. Therefore, aiming at the requirement of the phosphogypsum as a roadbed material, the new design and demonstration are carried out from the aspects of material performance, system composition and action mechanism of the phosphogypsum roadbed material so as to prepare the phosphogypsum roadbed material with excellent strength, water stability and volume stability.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic improvement. The phosphogypsum roadbed material is prepared by taking phosphogypsum as a main material and adding a cementing material or an additive; strength refers to the load capacity of the road base material; the water stability refers to the softening resistance of the road base material under the action of water soaking; volume stability refers to the shape retention capability of the road base material during service.
Aiming at the requirements of strength, water stability and volume stability of the phosphogypsum roadbed material, the patent provides an activation method of phosphogypsum, a water stability improvement method of the phosphogypsum roadbed material, a volume stability guarantee method of the phosphogypsum roadbed material and a waterproof performance improvement method of the phosphogypsum roadbed material so as to prepare the high-performance phosphogypsum roadbed material.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement, which is characterized by comprising the following steps:
(1) carrying out high-temperature calcination on phosphogypsum with the free water content of 7-20% in an environment of 100-1000 ℃ to obtain a high-temperature product;
(2) mixing a waterproof agent with hot water at 90-95 ℃ according to a mass ratio of 1:10-1:5 to obtain waterproof agent slurry;
(3) mixing the high-temperature product prepared in the step (1), the waterproof agent slurry prepared in the step (2) and Portland cement according to the mass percentage of 85-93 percent to 3.5-5 percent to 3-10 percent, and uniformly stirring to obtain the phosphorusGypsum road-based materials; wherein, in the portland cement, C3The mass fraction of the mineral A in the Portland cement is 2-5%, and a mineral admixture containing aluminosilicate cannot be doped in the Portland cement.
Further, in the step (1), the product obtained after the phosphogypsum is calcined at high temperature comprises any one or more of hemihydrate gypsum, type III anhydrite and type II anhydrite; wherein the calcining temperature for generating the semi-hydrated gypsum is between 100 and 170 ℃, the calcining temperature for generating the type III anhydrite is between 170 and 350 ℃, and the calcining temperature for generating the type II anhydrite is between 350 and 1000 ℃.
Further, in the step (1), the mass percentages of the hemihydrate gypsum, the type III anhydrite and the type II anhydrite generated in the phosphogypsum roadbed material are as follows: 0-35%, 10-85%, and 0-58%.
Further, in the step (2), the waterproof agent adopts a silane coupling agent and polyvinyl alcohol in a mass ratio of 1:4-1: 2.
The invention has the following advantages and beneficial effects:
1. the invention utilizes and exerts the hydration activity of the high-temperature activated phosphogypsum, and the strength and the water penetration resistance of a solidified body generated after hydration, thereby essentially improving the strength and the water stability of the phosphogypsum roadbed material.
2. The invention utilizes the characteristic that low-solubility C-S-H gel is formed after the silicate cement is hydrated, the silicate cement and the high-temperature activated phosphogypsum are mixed to prepare the phosphogypsum roadbed material, and the water stability of the phosphogypsum roadbed material is ensured by utilizing hydraulic substances.
3. The invention limits the C content in the Portland cement by avoiding the reaction of calcium aluminate and dihydrate gypsum to generate expansive hydration products3The content of the A mineral prohibits the application of the mineral admixture containing aluminosilicate in the portland cement, and fundamentally ensures the volume stability of the phosphogypsum roadbed material.
4. The invention seals the pores of the cured body of the phosphogypsum roadbed material by the waterproof agent prepared from polyvinyl alcohol and silane coupling agent, improves the water stability of the phosphogypsum roadbed material by utilizing the plugging effect and the hydrophobic effect of the waterproof agent, and provides guarantee for the long-term water stability of the phosphogypsum roadbed material.
In conclusion, the phosphogypsum roadbed material prepared by the invention can meet the performance requirements of the roadbed material on the effects of bearing vehicle load and environmental erosion (freezing and thawing, drying, water solution permeation and the like) in the service process, has good strength, water stability and volume stability, and has the advantages of simple preparation process, low production cost and wide raw material sources.
Detailed Description
The technical scheme of the invention is explained in detail by combining the following embodiments:
the invention provides a preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement, which comprises the following steps:
(1) carrying out high-temperature calcination on phosphogypsum with the free water content of 7-20% in an environment of 100-1000 ℃ to obtain a high-temperature product; the high-temperature product comprises any one or more of hemihydrate gypsum, type III anhydrite and type II anhydrite; wherein the calcining temperature for generating the semi-hydrated gypsum is between 100 and 170 ℃, the calcining temperature for generating the type III anhydrite is between 170 and 350 ℃, and the calcining temperature for generating the type II anhydrite is between 350 and 1000 ℃. Wherein the generated hemihydrate gypsum, type III anhydrite and type II anhydrite have the following mass percentages in the phosphogypsum roadbed material: 0-35%, 10-85%, 0-58%; the time required for high-temperature calcination of the phosphogypsum depends on the heat exchange efficiency inside the calcination equipment, so that the calcination time can be determined according to the working condition of the calcination equipment, and the calcination time can fluctuate from minutes to hours.
(2) Mixing a waterproof agent with hot water at 90-95 ℃ according to a mass ratio of 1:10-1:5 to obtain waterproof agent slurry; preferably, the waterproof agent adopts silane coupling agent and polyvinyl alcohol with the mass ratio of 1:4-1: 2; further, the silane coupling agent can adopt A151 type, and the polyvinyl alcohol can adopt 1799 type (for other types of silane coupling agents and polyvinyl alcohol, the implementation of the invention is not influenced);
(3) prepared by the step (1)Mixing the high-temperature product, the waterproof agent slurry prepared in the step (2) and Portland cement according to the mass percentage of 85% -93% to 3.5% -5% to 3% -10%, and uniformly stirring to obtain the phosphogypsum roadbed material; wherein, in the portland cement, C3The mass fraction of the mineral A in the Portland cement is 2-5%, and a mineral admixture containing aluminosilicate cannot be doped in the Portland cement.
The high-temperature activated phosphogypsum, the Portland cement and the waterproof agent slurry in the phosphogypsum roadbed material provided by the embodiment of the invention have the following mass percentages: (85% -93%), (3% -10%), (3.5% -5%), wherein the composition ratio of each raw material is shown in table 1:
TABLE 1 formulation method of phosphogypsum roadbed material
Note 1: indicates C in portland cement3And the mass fraction of A.
Note 2: the waterproof agent slurry comprises silane coupling agent, polyvinyl alcohol and hot water according to the mass ratio of the silane coupling agent to the polyvinyl alcohol to the hot water.
As shown in table 1, the above raw materials are measured and mixed according to a set ratio to form the phosphogypsum roadbed material, which can be transported to a construction site for roadbed construction and application.
The using method comprises the following steps: and (3) after the phosphogypsum roadbed material is transported to a construction site, measuring the moisture content by using a moisture content tester, and adjusting the moisture according to the difference between the tested moisture content and the expected moisture content. The expected water content is obtained in advance through a heavy type compaction method in a laboratory, the water content adjusting method is to use an atomization spraying device to spray materials conveyed to a construction site for many times, and a mixer is used for mixing the materials during spraying so as to enable the water content to be dispersed uniformly. And after the moisture adjustment is finished, compacting the roadbed by using the road roller, and achieving the expected compaction degree through multiple times of compaction, wherein the compaction degree is determined through a CBR test and a deflection test.
The validity of the invention is verified:
strength, water stability and volume stability pairs of samples prepared using a conventional phosphogypsum roadbed material (phosphogypsum: cement: fly ash: 72:8:20) and the phosphogypsum roadbed material proposed by the present invention based on high temperature activation and hydraulic improvement (high temperature activated phosphogypsum: portland cement: water-proofing agent: 87:8:5) are shown in table 2, wherein the strength is uniaxial compressive strength; the water stability is the strength retention rate relative to an air cured sample after being soaked in water for 24 hours; the volume stability is the expansion rate of the sample in an environment with the temperature of 20 ℃ and the relative humidity of 60 percent in the age of 180 days.
Table 2 comparison of the performance of conventional phosphogypsum roadbed material with that of the phosphogypsum roadbed material proposed by the present invention
The reaction mechanism involved in the present invention is as follows:
(I) activation of phosphogypsum: in the chemical production process of phosphorus, the main component of the phosphogypsum which is off-line and stockpiled is dihydrate gypsum. In thermodynamic terms, the dihydrate gypsum is in a stable state and has no cementing capacity; even though the dihydrate gypsum is compacted under the action of external force, the compacted body can generate certain strength (the dihydrate gypsum crystal particles are close to each other to generate Van der Waals force) in a non-soaking state, but the compacted body does not have water resistance (after the dihydrate gypsum crystal particles meet water, the contact points of the dihydrate gypsum crystal can be dissolved, and meanwhile, the dihydrate gypsum has higher solubility), and the strength can be obviously reduced or even broken up after the dihydrate gypsum is soaked for a long time. The phosphogypsum is calcined at high temperature, and the dihydrate gypsum gradually loses crystal water and is converted into hemihydrate gypsum, type III anhydrite or type II anhydrite in a high-temperature environment of 100-1000 ℃. After the semi-hydrated gypsum, the III type anhydrite and the II type anhydrite are contacted with water, hydration reaction is carried out to regenerate the dihydrate gypsum; the hydration reaction is a dissolving-crystallizing process, and dihydrate gypsum crystals generated by the hydration reaction are mutually contacted and crosslinked to form a compact consolidated body which has good strength and impermeability. Therefore, the invention proposes that phosphogypsum is calcined at high temperature to form hemihydrate gypsum, type III anhydrite or type II anhydrite (the process is called high-temperature activation of the phosphogypsum), then the high-temperature activated phosphogypsum is subjected to hydration reaction to form hydration products, and the strength and the permeability resistance of the phosphogypsum roadbed material are improved by means of mutual contact and crosslinking of the hydration products (dihydrate gypsum).
(II) improving the water stability of the phosphogypsum roadbed material: portland cement is a hydraulic cementing material (can be hardened in water and has good water-solubility resistance), and the Portland cement is contacted with water to perform hydration reaction to form hydration products (mainly C-S-H gel) with extremely low water solubility and cross-linked with each other, so that the Portland cement has good strength, permeability resistance and water stability. Therefore, the invention proposes to mix portland cement and high temperature activated phosphogypsum to form a roadbed material. After the Portland cement and the high-temperature activated phosphogypsum are mixed and subjected to hydration reaction, compact and crosslinked C-S-H gel and dihydrate gypsum can be formed, and the C-S-H gel has extremely low water solubility and has the functions of protecting and shielding the dihydrate gypsum formed after hydration. Therefore, the invention provides a method for preparing the subgrade material by using the mixture of the portland cement and the high-temperature activated phosphogypsum, so as to obviously improve the water stability of the phosphogypsum subgrade material.
(III) ensuring the volume stability of the phosphogypsum roadbed material: the Portland cement and the high-temperature activated phosphogypsum are mixed, so that the volume stability of the phosphogypsum roadbed material is also required to be noticed while the water stability of a solidified body is improved. Calcium aluminate component (C) in Portland cement3A) The reaction with dihydrate gypsum produces ettringite crystals with expansion capability and, at the same time, aluminosilicate materials used as mineral admixtures for portland cement (e.g.: fly ash, slag, metakaolin and the like), and the hydration activity is low, the rate of forming ettringite by hydration reaction with dihydrate gypsum is slower, so that the phosphogypsum roadbed material generates expansion damage in the service process and the volume stability of the phosphogypsum roadbed material is damaged. Therefore, the invention provides that in the silicate cement used for preparing the phosphogypsum roadbed material, C3The mass fraction of A is 2-5%, and the silicate cement must not be mixed with fly ash, slag and mountain rangeAnd low-activity aluminosilicate materials such as soil.
(IV) the waterproof performance of the phosphogypsum roadbed material is improved: when the C-S-H gel with excellent water stability is used for protecting the hydration product dihydrate gypsum of the high-temperature activated phosphogypsum, the pores of the cured body of the phosphogypsum roadbed material can be further sealed, so that the migration of water to the inside is further prevented, and the water stability of the phosphogypsum roadbed material is improved. The invention provides a waterproof agent prepared from a silane coupling agent and polyvinyl alcohol for sealing pores of a cured body of a phosphogypsum roadbed material, and the water stability of the cured body of the phosphogypsum roadbed material is improved by utilizing the plugging effect and the hydrophobic effect of the waterproof agent on the pores.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (3)
1. A preparation method of a phosphogypsum roadbed material based on high-temperature activation and hydraulic property improvement is characterized by comprising the following steps:
(1) carrying out high-temperature calcination on phosphogypsum with the free water content of 7-20% in an environment of 100-1000 ℃ to obtain a high-temperature product; the high-temperature product is composed of any one or more of semi-hydrated gypsum, type III anhydrite and type II anhydrite, and the mass percentages of the semi-hydrated gypsum, the type III anhydrite and the type II anhydrite in the phosphogypsum roadbed material are as follows: 0-35%, 10-85%, 0-58%;
(2) mixing a waterproof agent with hot water at 90-95 ℃ according to a mass ratio of 1:10-1:5 to obtain waterproof agent slurry; the waterproof agent adopts silane coupling agent and polyvinyl alcohol with the mass ratio of 1:4-1: 2;
(3) the high-temperature product prepared in the step (1), the waterproof agent slurry prepared in the step (2) and the Portland cementMixing 85-93 wt% and 3.5-5 wt% and 3-10 wt%, and stirring to obtain the phosphogypsum roadbed material; wherein, in the portland cement, C3The mass fraction of the mineral A in the Portland cement is 2-5%, and a mineral admixture containing aluminosilicate cannot be doped in the Portland cement.
2. The method for preparing phosphogypsum roadbed material according to claim 1, wherein in step (1), the calcination temperature for forming the hemihydrate gypsum is between 100 ℃ and 170 ℃, the calcination temperature for forming the type III anhydrite is between 170 ℃ and 350 ℃, and the calcination temperature for forming the type II anhydrite is between 350 ℃ and 1000 ℃.
3. The method for preparing phosphogypsum roadbed material according to claim 1, wherein the silane coupling agent is A151 type, and the polyvinyl alcohol is 1799 type.
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| CN111499324B (en) * | 2020-04-02 | 2022-06-03 | 湖北益通建设股份有限公司 | Low-toxicity phosphogypsum cemented macadam material and application thereof in road base course |
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