Multi-element solid waste synergistic excitation road material and preparation method thereof

Abstract

The invention discloses a multi-element solid waste synergistic excitation road material and a preparation method thereof. The multi-element solid waste synergistic excitation road material comprises the following raw material components: an activated matrix material (consisting of 85-90% of red mud, 7-15% of carbide slag and 3-5% of ardealite), and silica fume, 1-hydroxyethylidene-1, 1-diphosphonic acid, anhydrous sodium sulfate and water which respectively account for 4-6%, 0.2-0.4%, 0.8-1.2% and 30% of the mass of the activated matrix material. Pores are filled with silica fume in the raw materials, and C-S-H gel with low calcium-silicon ratio is generated, so that a water migration channel is blocked; hydroxyethylidene-1, 1-diphosphonic acid is chelated with free metal ions, saltpetering and ion interference are inhibited, and the ettringite structure is stabilized; carbide slag and ardealite cooperate to destroy a red mud silicon-aluminum network, accelerate dissolution of active ions and promote crystal generation; the anhydrous sodium sulfate accelerates formation of an ettringite framework through exogenous SO4 < 2->; the strength and water stability of the road material can be effectively improved. The raw materials are mainly industrial solid wastes, so that the consumption of natural resources is remarkably reduced, and the efficient collaborative consumption of a large amount of solid wastes is realized.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a multi-element solid waste synergistic stimulation road material and its preparation method. Background Technology

[0002] Currently, the generation of bulk solid waste is enormous. Historical stockpiling and inefficient disposal methods (such as stacking and landfilling) have led to serious environmental pollution, ecological risks, and resource waste, becoming a key bottleneck restricting the green and sustainable development of the economy and society. Solid wastes such as red mud, carbide slag, and phosphogypsum can be used to prepare roadbed materials for recycling, representing a viable green treatment option. However, their comprehensive utilization rate is currently low, and it is necessary to explore their large-scale application in roadbed materials and other fields.

[0003] Red mud is a large-scale, highly alkaline solid waste generated during the wet alumina production process, and its comprehensive utilization rate has long been below 10%, resulting in significant pressure for resource-based disposal. Red mud is mainly composed of silicate minerals and possesses potential pozzolanic activity. Using it as a major component in road fillers is considered an effective way to achieve large-scale disposal, possessing both significant theoretical value and promising engineering applications. While current research has made some progress in red mud-based road materials, it has significant limitations: auxiliary admixtures often use solid wastes with relatively high utilization rates, such as fly ash and blast furnace slag, with less attention paid to the synergistic effects with other low-utilization solid wastes (such as carbide slag and phosphogypsum), failing to fully explore the inherent strength potential of red mud itself.

[0004] Calcium carbide slag is a solid waste generated in chemical plants during the production of polyvinyl chloride (PVC) using the calcium carbide process. Its main component is calcium hydroxide, and it also contains toxic and harmful substances such as sulfides and phosphides. Currently, the comprehensive utilization rate of calcium carbide slag is low. Studies have shown that calcium carbide slag can supplement the calcium component and provide an alkaline environment in composite cementitious materials, possessing the potential to improve the strength of cementitious materials. However, in roadbed materials, calcium carbide slag is mostly used as a substitute for lime, with very little consideration given to the synergistic effect of multiple solid wastes, resulting in problems such as low material strength and poor durability.

[0005] Phosphogypsum is a byproduct of wet-process phosphoric acid or phosphate fertilizer production, with a comprehensive utilization rate of less than 50%. Rich in sulfate components, phosphogypsum can act as an effective activator, promoting the pozzolanic reactivity of siliceous alumina materials (such as red mud). Studies have shown that when red mud, slag powder, and other materials are combined with phosphogypsum, they can promote the formation of hydration products such as ettringite, filling pores and theoretically improving the density and engineering performance of the cementitious system. However, research on the application of phosphogypsum in roadbed materials is still in its early stages, and its large-scale engineering application faces fundamental challenges: as a major cementitious component, the material generally suffers from inherent defects such as low strength and poor water resistance, making it difficult to meet engineering requirements for road performance (especially water stability).

[0006] Therefore, on the one hand, it is urgent to significantly increase the scale of resource utilization of low-utilization solid wastes such as red mud and carbide slag, and overcome the technical bottleneck of poor water stability of phosphogypsum-based materials; on the other hand, it is necessary to consider the synergistic effect of multiple solid wastes to significantly improve the service performance of road materials. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-element solid waste synergistic stimulation road material and its preparation method, so as to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] One of the technical solutions of the present invention is a multi-component solid waste synergistic activation road material, the raw material components of which include an activated matrix material and silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water, with mass percentages of 4-6%, 0.2-0.4%, 0.8-1.2% and 30% of the activated matrix material, respectively.

[0010] The activated matrix materials include red mud, carbide slag, and phosphogypsum.

[0011] The functions and principles of each component are as follows:

[0012] In the activated matrix materials, red mud provides the aluminum required for the reaction, carbide slag provides sufficient alkaline environment and calcium ions necessary for the hydration reaction, and phosphogypsum provides the sulfates required for the reaction. Furthermore, carbide slag and phosphogypsum have the ability to activate red mud; the dissolution of carbide slag generates a large amount of hydroxide ions (OH-). - These ions rapidly disrupt the Si-O and Al-O bonds in red mud as the surface dissolves, thereby increasing the surface area for further reaction with the alkaline solution. Sulfates in phosphogypsum have the same effect. Under the synergistic effect of alkali (carbide slag) and sulfate (phosphogypsum), the Si-O and Al-O polyhedral network structures of some silica-alumina materials in red mud transform from a concentrated high-polymer state to a dispersed low-polymer state, disrupting the Si-O-Si and Si-O-Al network structures; subsequently, OH-... - It reacts with silica and aluminum minerals in multi-element solid waste, gradually eroding their surfaces, with Si and Al primarily forming [Al(OH)6]. 3- [H3AlO4] 2- [H3SiO4] - These ions enter the solution in plasma form and react with Ca... 2+ The red mud particles react to form crystals or gels using their surface as nucleation sites. However, under alkaline conditions, SO4... 2- It can displace some of the SiO4 in the gel product. 4- Continue with Ca 2+The formation of gel products accelerates the hydration reaction of silica-alumina minerals, thereby continuously improving the strength of cementitious materials.

[0013] Silica fume is used as an auxiliary cementing material. Red mud has a relatively low silicon content, resulting in CSH gels with a potentially high calcium-to-silicon ratio (Ca / Si) or CASH gels. These gels are more prone to depolymerization or dissolution under prolonged water exposure. Adding silica fume to the reaction system allows for the consumption of Ca(OH)₂ through a pozzolanic reaction, generating dense CSH gels with a low calcium-to-silicon ratio. This reduces the risk of depolymerization under water erosion and improves the material's water stability. Simultaneously, silica fume can fill pores, increasing density, blocking water migration channels, reducing saturated water content, and improving the material's freeze-thaw resistance.

[0014] The phosphonic acid group (-PO3H2) in the hydroxyethylidene diphosphonic acid (HEDP) molecule has a strong complexing ability with polyvalent metal ions, forming stable six-membered ring chelates. In red mud-based cementitious materials, HEDP can effectively immobilize free Na+. + Reduce alkali leaching and loose structure caused by alkaline dissolution, and fix soluble Al. 3+ / Fe 3+ To suppress the interference of these ions on the stability of hydration products (such as ettringite); at the same time, hydroxyethylidene diphosphonic acid and Ca 2+ The complexation can delay the conversion of ettringite (AFt) to monosulfide calcium sulfoaluminate (AFm), reduce microcracks caused by volume shrinkage, and thus improve the water stability and freeze-thaw resistance of the material. In addition, hydroxyethylidene diphosphonic acid can also promote the formation of low calcium-to-silicon ratio (CSH) by consuming free Ca(OH)2, thereby enhancing the stability of the gel structure.

[0015] Anhydrous sodium sulfate acts as an early-strength agent. Hydroxyethylidene diphosphonic acid may excessively chelate Ca. 2+ This slows down the hydration reaction, resulting in slow early strength development. The addition of anhydrous sodium sulfate provides exogenous sulfate ions, increasing the SO42- content in the system. 2- Concentration accelerates Ca 2+ The leaching and precipitation of hydration products advance the hydration exothermic peak, while simultaneously reacting with active Al in the red mud. 3+ / Ca in carbide slag 2+ The reaction rapidly generates a needle-like ettringite framework, thereby improving early strength.

[0016] The synergistic effect of the above components can effectively improve the water stability, frost resistance, and strength of road materials. Furthermore, this invention can significantly increase the scale of resource utilization of low-utilization solid wastes such as red mud.

[0017] Furthermore, by mass percentage, the raw material composition of the activated matrix material is: 85-90% red mud, 7-15% carbide slag, and 3-5% phosphogypsum.

[0018] Preferably, the red mud is dried red mud, which is a reddish-brown dry powder with the main chemical components being Fe2O3, Al2O3, and SiO2, and a pH value ≥10.5, exhibiting strong alkalinity.

[0019] Preferably, the carbide slag is dried carbide slag, which is a gray-black dry powder with Ca(OH)2 as its main chemical component and a mass content of ≥90%.

[0020] Preferably, the phosphogypsum is a pre-treated and dried phosphogypsum, which is a grayish-white or light yellow powder with CaSO4·2H2O as its main chemical component and a mass content of ≥90%.

[0021] Preferably, the silica fume is an extremely fine gray powder, with its main chemical component being amorphous SiO2; the specific surface area of ​​the silica fume is ≥15,000 m². 2 / kg, with an average particle size of 0.1-0.3μm and an activity index ≥105%.

[0022] Preferably, the hydroxyethylidene diphosphonic acid (HEDP) is a white crystalline powder or a transparent viscous liquid, with C2H8O7P2 as its main component and a purity ≥98%.

[0023] Preferably, the anhydrous sodium sulfate is a white crystalline powder or granules, the main chemical component of which is Na2SO4, and its mass content is ≥99.0%.

[0024] The second technical solution of the present invention: a method for preparing the above-mentioned multi-element solid waste synergistic road-use material, comprising the following steps:

[0025] Weigh each raw material component according to the mass ratio; mix red mud, carbide slag, phosphogypsum, silica fume and anhydrous sodium sulfate, stir to obtain a dry powder material; mix hydroxyethylidene diphosphonic acid and water, stir to obtain a solution; mix the dry powder material and the solution, stir to obtain a slurry; cure and shape the slurry to obtain the multi-element solid waste synergistic road material.

[0026] Preferably, before weighing each raw material component according to the mass ratio, the process further includes drying, grinding, and sieving the red mud, carbide slag, and phosphogypsum. That is, the weighed red mud is the dried, ground, and sieved red mud, and the weighed carbide slag is the dried, ground, and sieved carbide slag.

[0027] Preferably, the grinding is specifically grinding to the point where it can pass through a 200-mesh sieve.

[0028] Preferably, before drying, grinding, and sieving the phosphogypsum, a water washing pretreatment step is included. That is, the weighed phosphogypsum is the phosphogypsum after water washing pretreatment, drying, grinding, and sieving.

[0029] Optionally, the water washing pretreatment is performed three times, with the solid-liquid ratio of phosphogypsum to water being 1:3 during each wash.

[0030] The purpose of water washing pretreatment of phosphogypsum is to remove soluble phosphorus, fluorine and organic matter from the phosphogypsum, and to prevent the PO4 in the phosphogypsum from becoming too high. 3- F - It competes with hydroxyethylidene diphosphonic acid for metal ions.

[0031] Preferably, after mixing red mud, carbide slag, phosphogypsum, silica fume and anhydrous sodium sulfate, the stirring speed is ≥800 r / min and the stirring time is 2-6 min.

[0032] Preferably, the stirring time after mixing hydroxyethylidene diphosphonic acid and water is 5 minutes.

[0033] Preferably, after mixing the dry powder material and the solution, the stirring speed is ≥1200 r / min, and the stirring time is 2-6 min.

[0034] The present invention discloses the following technical effects:

[0035] The raw materials of this invention are mainly industrial solid waste, which can reduce soil alkalization and phosphorus and fluorine leakage pollution caused by red mud storage, making it green, low-carbon and environmentally friendly.

[0036] This invention optimizes the dosage of each component through experiments, thereby meeting the requirements of road material specifications for unconfined compressive strength, water stability, and frost resistance of road materials.

[0037] In the activated matrix material of this invention, red mud accounts for 85-90%, and combined with low-utilization solid wastes such as carbide slag and phosphogypsum, the total proportion of solid waste in the solid components exceeds 95%, which significantly reduces the consumption of natural resources and achieves efficient and synergistic disposal of bulk solid waste.

[0038] In this invention, silica fume fills the pores in the raw materials and generates a low-calcium-to-silicon ratio CSH gel, blocking water migration channels and reducing the risk of depolymerization. Simultaneously, it chelates free Na+ through hydroxyethylidene diphosphonic acid. + / Al 3+ / Fe 3+ It can suppress alkali blooming and ion interference, stabilize the structure of ettringite (AFt), reduce shrinkage microcracks, and effectively solve the problem of insufficient water stability of phosphogypsum-based materials.

[0039] In this invention, carbide slag and phosphogypsum synergistically disrupt the silica-alumina network of red mud, accelerating the dissolution of active ions and promoting crystal formation. Anhydrous sodium sulfate compensates for the delayed chelation of calcium ions by hydroxyethylidene diphosphonic acid, and exogenous SO4 is used to further enhance the effect. 2-Accelerating the formation of ettringite skeleton can effectively solve the problem of insufficient strength in phosphogypsum-based materials. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0042] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0043] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0044] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0045] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0046] In the following embodiments and comparative examples of the present invention, room temperature refers specifically to 20-30°C.

[0047] Unless otherwise specified, all raw materials used in the following embodiments and comparative examples of this invention are commercially available products. The red mud is dried Bayer process red mud powder (moisture content ≤1%), sourced from the Zibo branch of Aluminum Corporation of China Limited, with a pH of 11.0 and a specific surface area of ​​649.33 m². 2 / kg; the phosphogypsum came from a phosphate fertilizer plant in Hubei Province, with a pH of 4.9 and a specific surface area of ​​433.14 m². 2 / kg, the mass content of CaSO4·2H2O is 91.08%; the calcium carbide slag is dried calcium carbide slag powder (moisture content ≤1%), from a power plant in Shandong, with a pH of 11.1 and a specific surface area of ​​720.95 m². 2 / kg, Ca(OH)2 content is 90.57%; silica fume was purchased from Henan Jinrun New Materials Co., Ltd., with a purity of 96%, an average particle size of 0.3μm, an activity index of 105%, and a specific surface area of ​​19100.00m². 2 / kg; Hydroxyethylidene diphosphonic acid was purchased from Shanghai Maclean Biochemical Co., Ltd., with a purity of 98%; Anhydrous sodium sulfate was purchased from Sinopharm Reagent, with a mass content (i.e., purity) of 99.0%.

[0048] Comparative Example 1

[0049] The sample in this comparative example consisted only of an activated matrix material and water. The mass of water was 30% of the mass of the activated matrix material, which was red mud.

[0050] The preparation method of the above-mentioned sample is as follows:

[0051] Step 1: Grind the dried red mud thoroughly and pass it through a 200-mesh sieve to increase its specific surface area, improve its reactivity, and facilitate the formation of a denser structure;

[0052] Step 2: Weigh out the appropriate amounts of ground and sieved red mud and water according to the raw material mass ratio;

[0053] Step 3: Put the red mud into the mixing bucket, pour water into the mixing bucket and mix. Use a mixer to mix for 5 minutes until it is evenly mixed. The mixer speed is 1200 r / min.

[0054] Step 4: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0055] Comparative Example 2

[0056] The sample in this comparative example consisted only of activated matrix material and water, with the mass of water being 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 95% red mud, 3% carbide slag, and 2% phosphogypsum.

[0057] The preparation method of the above-mentioned sample is as follows:

[0058] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0059] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0060] Step 3: Weigh out the corresponding weights of ground and sieved red mud, carbide slag, phosphogypsum, and water according to the raw material mass ratio;

[0061] Step 4: Put the red mud, carbide slag, and phosphogypsum into a mixer and mix them for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0062] Step 5: Pour water into the mixing bowl and mix with the dry powder material. Use a mixer to mix for 5 minutes until the mixture is evenly mixed. The mixer speed is 1200 rpm.

[0063] Step 6: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure until the target age. Demold to obtain the test block.

[0064] Comparative Example 3

[0065] The sample in this comparative example consisted only of an activated matrix material and water, with the water accounting for 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 90% red mud and 10% phosphogypsum.

[0066] The preparation method of the above-mentioned sample is as follows:

[0067] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0068] Step 2: Thoroughly grind the red mud (dried) and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0069] Step 3: Weigh out the appropriate amounts of ground and sieved red mud, phosphogypsum, and water according to the raw material mass ratio;

[0070] Step 4: Put the red mud and phosphogypsum into the mixer and mix for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into the mixing bucket for later use.

[0071] Step 5: Pour water into the mixing bowl and mix with the dry powder material. Use a mixer to mix for 5 minutes until the mixture is evenly mixed. The mixer speed is 1200 rpm.

[0072] Step 6: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure until the target age. Demold to obtain the test block.

[0073] Comparative Example 4

[0074] The sample in this comparative example consisted only of activated matrix material and water, with the mass of water being 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 90% red mud, 3% carbide slag, and 7% phosphogypsum.

[0075] The preparation method of the above samples is the same as that of Comparative Example 2.

[0076] Comparative Example 5

[0077] The sample in this comparative example consisted only of an activated matrix material and water, with the water accounting for 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 90% red mud, 7% carbide slag, and 3% phosphogypsum.

[0078] The preparation method of the above samples is the same as that of Comparative Example 2.

[0079] Comparative Example 6

[0080] The sample in this comparative example consisted only of activated matrix material and water, with the mass of water being 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 90% red mud and 10% carbide slag.

[0081] The preparation method of the above-mentioned sample is as follows:

[0082] Step 1: Grind the dried red mud and carbide slag thoroughly and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0083] Step 2: Weigh out the appropriate amounts of ground and sieved red mud, carbide slag, and water according to the raw material mass ratio;

[0084] Step 3: Put the red mud and carbide slag into the mixer and mix them for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into the mixing bucket for later use.

[0085] Step 4: Pour water into the mixing bowl and mix with the dry powder. Use a mixer to mix for 5 minutes until the mixture is evenly mixed. The mixer speed is 1200 rpm.

[0086] Step 5: Pour the well-stirred slurry into the mold, smooth the surface to form a sample, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0087] Comparative Example 7

[0088] The sample in this comparative example consisted only of an activated matrix material and water, with the water accounting for 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 85% red mud and 15% phosphogypsum.

[0089] The preparation method of the above samples is the same as that of Comparative Example 3.

[0090] Comparative Example 8

[0091] The sample in this comparative example consisted only of an activated matrix material and water, with the water accounting for 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 85% red mud, 5% carbide slag, and 10% phosphogypsum.

[0092] The preparation method of the above samples is the same as that of Comparative Example 2.

[0093] Comparative Example 9

[0094] The sample in this comparative example consisted only of an activated matrix material and water, with the water accounting for 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0095] The preparation method of the above samples is the same as that of Comparative Example 2.

[0096] Comparative Example 10

[0097] The sample in this comparative example consisted only of activated matrix material and water, with the mass of water being 30% of the mass of the activated matrix material. The activated matrix material was composed of the following raw material components by mass percentage: 85% red mud and 15% carbide slag.

[0098] The preparation method of the above-mentioned samples is the same as that of Comparative Example 6.

[0099] Comparative Example 11

[0100] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), and water. The mass of HEDDI constituted 0.2% of the activated matrix material, and the mass of water constituted 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0101] The preparation method of the above-mentioned sample is as follows:

[0102] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0103] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0104] Step 3: Weigh out the corresponding mass of ground and sieved red mud, carbide slag and phosphogypsum, as well as hydroxyethylidene diphosphonic acid and water according to the raw material mass ratio;

[0105] Step 4: Put the red mud, carbide slag, and phosphogypsum into a mixer and mix them for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0106] Step 5: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0107] Step 6: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until the mixture is uniform. The mixer speed is 1200 r / min.

[0108] Step 7: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0109] Comparative Example 12

[0110] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), and water. The mass of HEDDI constituted 0.4% of the activated matrix material, and the mass of water constituted 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0111] The preparation method of the above-mentioned samples is the same as that of Comparative Example 11.

[0112] Comparative Example 13

[0113] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), and water. The mass of HEDDI constituted 0.6% of the activated matrix material, and the mass of water constituted 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0114] The preparation method of the above-mentioned samples is the same as that of Comparative Example 11.

[0115] Comparative Example 14

[0116] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The mass of HEDDI was 0.4% of the activated matrix material, the mass of anhydrous sodium sulfate was 0.8% of the activated matrix material, and the mass of water was 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0117] The preparation method of the above-mentioned sample is as follows:

[0118] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0119] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0120] Step 3: Weigh out the corresponding mass of ground and sieved red mud, carbide slag and phosphogypsum, as well as hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0121] Step 4: Put the red mud, carbide slag, phosphogypsum and anhydrous sodium sulfate into a mixer and stir for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0122] Step 5: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0123] Step 6: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until the mixture is uniform. The mixer speed is 1200 r / min.

[0124] Step 7: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0125] Comparative Example 15

[0126] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The mass of HEDDI was 0.4% of the activated matrix material, the mass of anhydrous sodium sulfate was 1.2% of the activated matrix material, and the mass of water was 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0127] The preparation method of the above-mentioned samples is the same as that of Comparative Example 14.

[0128] Comparative Example 16

[0129] The sample in this comparative example consisted of an activated matrix material, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The mass of HEDDI was 0.4% of the activated matrix material, the mass of anhydrous sodium sulfate was 1.6% of the activated matrix material, and the mass of water was 30% of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0130] The preparation method of the above-mentioned samples is the same as that of Comparative Example 14.

[0131] Example 1

[0132] The sample in this embodiment consists of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The silica fume accounts for 2% of the activated matrix material by mass, HEDDI comprises 0.4%, anhydrous sodium sulfate 1.2%, and water 30%. The activated matrix material is composed of the following components by mass percentage: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0133] The preparation method of the above-mentioned sample is as follows:

[0134] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0135] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0136] Step 3: Weigh out the corresponding mass of ground and sieved red mud, carbide slag and phosphogypsum, as well as silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0137] Step 4: Put the red mud, carbide slag, phosphogypsum, silica fume and anhydrous sodium sulfate into a mixer. Stir for 3 minutes in a dry state until the mixture is uniform. The mixer speed is 800 r / min. Then put the uniformly mixed dry powder into a mixing bucket for later use.

[0138] Step 5: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0139] Step 6: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until the mixture is uniform. The mixer speed is 1200 r / min.

[0140] Step 7: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0141] Example 2

[0142] The sample in this embodiment consists of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The silica fume accounts for 4% of the mass of the activated matrix material, the HEDDI comprises 0.4%, the anhydrous sodium sulfate 1.2%, and the water 30%. The activated matrix material is composed of the following components by mass percentage: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0143] The preparation method of the above-mentioned samples is the same as that in Example 1.

[0144] Example 3

[0145] The sample in this embodiment consists of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The silica fume accounts for 6% of the mass of the activated matrix material, the HEDDI comprises 0.4%, the anhydrous sodium sulfate 1.2%, and the water 30%. The activated matrix material is composed of the following components by mass percentage: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0146] The preparation method of the above-mentioned samples is the same as that in Example 1.

[0147] Comparative Example 17

[0148] The sample in this comparative example consisted of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate, and water. The silica fume accounted for 6% of the mass of the activated matrix material, the hydroxyethylidene diphosphonic acid accounted for 0.4% of the mass of the activated matrix material, the anhydrous sodium sulfate accounted for 1.2% of the mass of the activated matrix material, and the water accounted for 30% of the mass of the activated matrix material. The activated matrix material consisted of the following raw material components by mass percentage: 90% red mud and 10% carbide slag.

[0149] The preparation method of the above-mentioned sample is as follows:

[0150] Step 1: Grind the dried red mud and carbide slag thoroughly and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0151] Step 2: Weigh out the corresponding mass of ground and sieved red mud and carbide slag, as well as silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0152] Step 3: Put the red mud, carbide slag, silica fume and anhydrous sodium sulfate into a mixer and stir for 3 minutes in a dry state until it is evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0153] Step 4: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0154] Step 5: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until it is evenly mixed. The mixer speed is 1200 r / min.

[0155] Step 6: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure until the target age. Demold to obtain the test block.

[0156] Comparative Example 18

[0157] The sample in this comparative example consisted of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid (HEDDI), anhydrous sodium sulfate, and water. The silica fume accounted for 6% of the mass of the activated matrix material, the HEDDI for 0.4%, the anhydrous sodium sulfate for 1.2%, and the water for 30%. The activated matrix material, by mass percentage, consisted of 85% red mud and 15% phosphogypsum.

[0158] The preparation method of the above-mentioned sample is as follows:

[0159] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0160] Step 2: Thoroughly grind the red mud (dried) and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0161] Step 3: Weigh out the corresponding mass of ground and sieved red mud and phosphogypsum, as well as silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0162] Step 4: Put red mud, phosphogypsum, silica fume and anhydrous sodium sulfate into a mixer and stir for 3 minutes in a dry state until evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0163] Step 5: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0164] Step 6: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until the mixture is uniform. The mixer speed is 1200 r / min.

[0165] Step 7: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0166] Comparative Example 19

[0167] The sample in this comparative example consisted of an activated matrix material, silica fume, anhydrous sodium sulfate, and water. The silica fume accounted for 6% of the activated matrix material by mass, the anhydrous sodium sulfate accounted for 1.2% of the activated matrix material by mass, and the water accounted for 30% of the activated matrix material by mass. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0168] The preparation method of the above-mentioned sample is as follows:

[0169] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0170] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0171] Step 3: Weigh out the corresponding mass of ground and sieved red mud, carbide slag and phosphogypsum, as well as silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0172] Step 4: Put the red mud, carbide slag, phosphogypsum, silica fume and anhydrous sodium sulfate into a mixer. Stir for 3 minutes in a dry state until the mixture is uniform. The mixer speed is 800 r / min. Then put the uniformly mixed dry powder into a mixing bucket for later use.

[0173] Step 5: Pour water into the mixing bowl and mix with the dry powder material. Use a mixer to mix for 5 minutes until the mixture is evenly mixed. The mixer speed is 1200 rpm.

[0174] Step 6: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure until the target age. Demold to obtain the test block.

[0175] Comparative Example 20

[0176] The sample in this comparative example consisted of an activated matrix material, silica fume, hydroxyethylidene diphosphonic acid (HEDDI), and water. The silica fume accounted for 2% of the mass of the activated matrix material, the HEDDI for 0.4% of the mass of the activated matrix material, and the water for 30% of the mass of the activated matrix material. The activated matrix material, by mass percentage, consisted of the following raw material components: 85% red mud, 10% carbide slag, and 5% phosphogypsum.

[0177] The preparation method of the above-mentioned sample is as follows:

[0178] Step 1: Mix phosphogypsum and water at a solid-liquid ratio of 1:3 and perform water washing pretreatment. Perform water washing pretreatment 3 times in total, and then dry after water washing pretreatment.

[0179] Step 2: Thoroughly grind the red mud (dried), carbide slag (dried), and phosphogypsum (washed and dried) and pass them through a 200-mesh sieve to increase their specific surface area, improve their reactivity, and facilitate the formation of a denser structure.

[0180] Step 3: Weigh out the corresponding mass of ground and sieved red mud, carbide slag and phosphogypsum, as well as silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate and water according to the raw material mass ratio;

[0181] Step 4: Put the red mud, carbide slag, phosphogypsum and silica fume into a mixer and mix for 3 minutes in a dry state until they are evenly mixed. The mixer speed is 800 r / min. Then put the evenly mixed dry powder into a mixing bucket for later use.

[0182] Step 5: Pour hydroxyethylidene diphosphonic acid and water into a beaker and stir continuously with a glass rod for 5 minutes until homogeneous;

[0183] Step 6: Quickly pour the well-mixed solution in the beaker into the mixing bowl and mix it with the dry powder material. Use a mixer to stir for 5 minutes until the mixture is uniform. The mixer speed is 1200 r / min.

[0184] Step 7: Pour the well-stirred slurry into the mold, smooth the surface, and then place it in a standard curing chamber to cure to the target age. Demold to obtain the test block.

[0185] The above comparative examples and embodiments demonstrate the effects of the proportions of red mud, carbide slag, and phosphogypsum, the amount of silica fume, the amount of hydroxyethylidene diphosphonic acid, and the amount of anhydrous sodium sulfate on the unconfined compressive strength, water stability, and antifreeze properties of the multi-component solid waste synergistically activated road materials. For ease of comparison, the proportions of all comparative examples and embodiments are summarized in Table 2, where red mud, carbide slag, and phosphogypsum represent their respective mass percentages in the activated matrix material, and other components represent percentages of the activated matrix material's mass.

[0186] Table 2 Comparison of percentages and dosages of each component in the comparative examples and embodiments.

[0187]

[0188]

[0189] Test case

[0190] Fifteen test blocks were prepared for Comparative Examples 9, 11-16, 17-20, and Examples 1-3 respectively. Nine blocks were used for unconfined compressive strength testing at 1d, 7d, and 28d; three blocks were used for water stability testing; and three blocks were used for frost resistance testing. Nine test blocks were prepared for Comparative Examples 1-8 and 10 respectively for unconfined compressive strength testing at 1d, 7d, and 28d. Specifically, the unconfined compressive strength and frost resistance at 1d, 7d, and 28d were determined according to the methods described in industry standard JTG E51-2009 "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering". The unconfined compressive strength and freeze-thaw coefficient measured for each comparative example or example were the average of three parallel samples. The water stability performance was determined according to the methods described in industry standard CJ / T 486-2015 "Soil Stabilizing Admixtures". The water stability coefficient measured for each comparative example or example was the average of three parallel samples. According to the industry standard JTG D50-2017 "Specifications for Design of Asphalt Pavement for Highways", the 7-day compressive strength requirement for base course materials of different road grades is between 4 and 6 MPa. This invention takes 6 MPa as the benchmark value. According to the industry standard JTG / T 3310-2019 "Specifications for Durability Design of Concrete Structures in Highway Engineering", the freeze-thaw coefficient must be ≥0.75. Referring to the industry standard CJJ / T 286-2018 "Technical Standard for Application of Soil Stabilizers", the water stability coefficient must be ≥0.80. The experimental test results are shown in Table 3.

[0191] Table 3 Comparison of experimental results for each comparative example and embodiment

[0192]

[0193]

[0194] Table 3 shows that the 7-day unconfined compressive strength of Comparative Example 1 was only 1.33 MPa, while the 7-day unconfined compressive strengths of Comparative Examples 3 and 7 were 1.53 MPa and 1.63 MPa, respectively, not significantly different from Comparative Example 1. This indicates that adding phosphogypsum to red mud alone has little effect on improving the 7-day unconfined compressive strength. However, the 7-day unconfined compressive strengths of Comparative Examples 6 and 10 reached 6.07 MPa and 6.88 MPa, respectively, indicating that even adding carbide slag alone can significantly enhance the strength of the red mud system. Comparing Comparative Examples 2, 4, 5, 8, and 9, it is clear that when the proportion of carbide slag in the red mud-carbide slag-phosphogypsum system is greater than that of phosphogypsum, the improvement in 7-day unconfined compressive strength is more significant. Furthermore, comparing Comparative Examples 5 and 6 with Comparative Examples 9 and 10, the strength improvement effect of adding only carbide slag or phosphogypsum was not as good as the combined effect of the ternary solid wastes. Moreover, the 7-day unconfined compressive strength of Comparative Examples 5, 6, 9, and 10 met the required compressive strength (6.0 MPa) specified in the standard. In conclusion, the recommended proportions are: red mud 85-90%, carbide slag 7-15%, and phosphogypsum 3-5%.

[0195] Comparative Examples 9 and 11-13, with a fixed optimal dosage of red mud-carbide slag-phosphogypsum, investigated the effect of hydroxyethylidene diphosphonic acid (HEDA) dosage on the unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient of the samples. The freeze-thaw coefficient and 7-day unconfined compressive strength of Comparative Examples 9 and 11-13 met the specifications, while the water stability coefficients of Comparative Examples 11 and 12 met the specifications. Compared to Comparative Examples 9 and 11-13, with increasing HEDA dosage, the 1-day unconfined compressive strength of the samples continuously decreased. The 7-day unconfined compressive strength of Comparative Examples 11 and 12 was not significantly different from that of Comparative Example 9, while their 28-day unconfined compressive strength was greater than that of Comparative Example 9. Comparative Example 13 showed a significant decrease in 1-day, 7-day, and 28-day unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient. Therefore, the recommended HEDA dosage is 0.2-0.4%.

[0196] Comparing Comparative Examples 12 and 14-16, the effect of anhydrous sodium sulfate dosage on the unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient of the samples was investigated. The water stability coefficient, freeze-thaw coefficient, and 7-day unconfined compressive strength of Comparative Examples 12 and 14-16 all met the specification requirements. Compared with Comparative Examples 12 and 14-16, with the increase of anhydrous sodium sulfate dosage, the 1-day unconfined compressive strength of the samples increased significantly, the 7-day unconfined compressive strength and water stability coefficient increased slightly, and the 28-day unconfined compressive strength and freeze-thaw coefficient gradually decreased. The decrease was greater in Comparative Example 16 than in Comparative Examples 14 and 15. Therefore, the recommended dosage of anhydrous sodium sulfate is 0.8-1.2%.

[0197] By comparing Comparative Example 15 and Examples 1-3, the effect of silica fume content on the unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient of the samples was investigated. The water stability coefficient, freeze-thaw coefficient, and 7-day unconfined compressive strength of Comparative Example 15 and Examples 1-3 all met the specifications. Compared with Comparative Example 15 and Example 1, the unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient of the samples did not change significantly. Compared with Comparative Example 15, Examples 2, and Examples 3, the unconfined compressive strength, water stability coefficient, and freeze-thaw coefficient of Examples 2 and 3 increased significantly. Therefore, the recommended silica fume content is 4-6%.

[0198] Compared with Comparative Examples 17-20, the water stability coefficient and freeze-thaw coefficient of Comparative Examples 17-20 are lower than those of Comparative Examples 3, indicating that each component in the raw materials plays its own role and is indispensable. The compressive strength of Example 3 is greater than that of Comparative Examples 17, 18, and 20. The 1-day and 7-day compressive strength of Example 3 is slightly lower than that of Comparative Example 19, but the 28-day compressive strength of Example 3 is greater than that of Comparative Example 19.

[0199] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A multi-element solid waste synergistic activation road material, characterized in that, The raw material components include an activated matrix material and silica fume, hydroxyethylidene diphosphonic acid, anhydrous sodium sulfate, and water, with mass percentages of 4-6%, 0.2-0.4%, 0.8-1.2%, and 30% of the activated matrix material, respectively. The activated matrix materials include red mud, carbide slag, and phosphogypsum.

2. The multi-element solid waste synergistic stimulation road material as described in claim 1, characterized in that, The raw material composition of the activated matrix material, by mass percentage, is: 85-90% red mud, 7-15% carbide slag, and 3-5% phosphogypsum.

3. The method for preparing multi-element solid waste synergistically activated road materials as described in any one of claims 1-2, characterized in that, Includes the following steps: Weigh each raw material component according to the mass ratio; mix red mud, carbide slag, phosphogypsum, silica fume and anhydrous sodium sulfate, stir to obtain a dry powder material; mix hydroxyethylidene diphosphonic acid and water, stir to obtain a solution; mix the dry powder material and the solution, stir to obtain a slurry; cure and shape the slurry to obtain the multi-element solid waste synergistic road material.

4. The preparation method of the multi-element solid waste synergistic activation road material as described in claim 3, characterized in that, Before weighing each raw material component according to the mass ratio, the process also includes drying, grinding, and sieving the red mud, carbide slag, and phosphogypsum.

5. The preparation method of the multi-element solid waste synergistic activation road material as described in claim 4, characterized in that, The grinding process specifically refers to grinding the powder until it can pass through a 200-mesh sieve.

6. The preparation method of the multi-element solid waste synergistic activation road material as described in claim 4, characterized in that, Before drying, grinding, and sieving phosphogypsum, the process also includes a water washing pretreatment step.

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