Aluminum ash-based light mixing pile and construction method thereof

Abstract

The invention discloses an aluminum ash-based light mixing pile and a construction method thereof, and relates to the technical field of traffic engineering foundation treatment. The aluminum ash-based light mixing pile is of a porous structure formed by mixing and stirring light solidified slurry and soft clay. The raw materials of the light curing slurry comprise cement and secondary aluminum ash, and the addition amounts of the cement and the secondary aluminum ash are respectively 10-15% and 5-10% of the weight of the soft clay. The light curing slurry is adopted for treating the soft foundation to form the stirring pile, and the permeability and compressibility of the stirring pile can be effectively improved while the strength of the stirring pile is guaranteed. The invention further discloses a construction method of the aluminum ash-based light mixing pile, the component characteristics of the secondary aluminum ash are fully utilized, the secondary aluminum ash serves as one of main raw materials, the characteristic that the secondary aluminum ash generates ammonia gas through hydration reaction is utilized, pores are provided for the mixing pile, the self weight can be reduced, drainage can be accelerated, and the mixing pile has certain compressibility.

Description

Technical Field

[0001] The present invention relates to the technical field of transportation engineering foundation treatment, and in particular to an aluminum ash slag-based lightweight mixing pile and a construction method thereof. Background Art

[0002] Due to the special geographical location and complex geological conditions in coastal areas, various soft foundations are inevitably encountered during the construction of high-grade highways. The soft clay in the soft foundation has the characteristics of high water content, low permeability, low shear strength and high compressibility. Therefore, in order to ensure the safety, applicability and driving comfort of the highway, corresponding foundation treatment is required during the construction period. The commonly used treatment method is to drive mixing piles into the soft foundation to form a pile-soil composite foundation, thereby enhancing the foundation's ability to bear the stress of the overlying embankment and traffic loads.

[0003] At present, traditional mixing pile construction methods generally use cement-based slurry (i.e., Portland cement mixed with water to form a slurry) for mixing pile construction. The strength of the pile-soil composite foundation is controlled by controlling the water-cement ratio and cement content of the cement-based slurry. However, traditional cement-based slurry is not suitable for soft foundations with high moisture content and high compressibility. Mixing piles formed using traditional cement-based slurry have a low permeability coefficient and poor permeability. They require too long for water to seep in, which cannot meet the demand for rapid "seepage". Therefore, if traditional cement-based slurry is used to form mixing piles in soft foundations, it is difficult to quickly drain water from the soft clay, which is not conducive to the formation of early strength of the pile body. Moreover, mixing piles formed using traditional cement-based slurry have a high degree of density and low compressibility, while soft clay has high compressibility. Under load, the deformation between the mixing pile body and the soil between the piles is not coordinated, resulting in uneven settlement of the pile-soil composite foundation, which can easily cause cracking or damage to buildings or roads on the foundation. Therefore, improving the mixing pile so that it can meet the strength requirements while also having good permeability and compressibility is of great significance in the treatment of soft foundations. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an aluminum ash slag-based lightweight mixing pile, which is a porous structure made by mixing lightweight solidified slurry and soft clay, and has not only better strength but also good permeability and compressibility.

[0005] The technical problem to be solved by the present invention is also to provide a construction method for aluminum ash slag-based lightweight mixing piles, which fully utilizes the composition characteristics of secondary aluminum ash, uses it as one of the main raw materials, and utilizes its property of generating ammonia through hydration reaction to provide pores for the mixing piles, which can not only reduce the dead weight, but also accelerate drainage and make the mixing piles have a certain compressibility.

[0006] To solve the above technical problems, the present invention provides an aluminum ash residue-based lightweight mixing pile, which is a porous structure made by mixing a lightweight solidified slurry with soft clay;

[0007] The raw materials of the lightweight solidified slurry include cement and secondary aluminum ash, and the addition amounts of the cement and the secondary aluminum ash are respectively 10% - 15% and 5% - 10% of the weight of the soft clay;

[0008] Calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 15% - 25% of AlN;

[0009] As an improvement of the above technical solution, calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% of Al2O3, 15% - 25% of AlN, 5% - 10% of SiO2, 3% - 8% of CaO, 1% - 5% of MgO, 0.5% - 5% of Fe2O3, chloride salt ≤ 2%, fluoride salt ≤ 2% and other impurities 1% - 5%.

[0010] As an improvement of the above technical solution, calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% of Al2O3, 15% - 25% of AlN, 5% - 10% of SiO2, 3% - 8% of CaO, 1% - 5% of MgO, 0.5% - 5% of Fe2O3, chloride salt 0 - 0.5%, fluoride salt 0 - 0.5% and other impurities 1% - 5%.

[0011] As an improvement of the above technical solution, the water content of the soft clay is 35% - 75%, and the compression coefficient of the soft clay is ≥ 0.5 MPa -1 。

[0012] As an improvement of the above technical solution, the particle size of the secondary aluminum ash is 5 μm - 50 μm, and the average particle size is 10 μm - 15 μm.

[0013] As an improvement of the above technical solution, the water-cement ratio of the lightweight solidified slurry is 0.45 - 0.55.

[0014] As an improvement of the above technical solution, the raw materials of the lightweight solidified slurry further include a water reducer, and the addition amount of the water reducer is 0.1% - 0.8% of the weight of the soft clay.

[0015] As an improvement of the above technical solution, there are through drainage pores inside the porous structure of the aluminum ash residue-based lightweight mixing pile, and the pore diameter of the drainage pores is 0.1 μm - 1 μm;

[0016] The unit weight of the aluminum ash residue-based lightweight mixing pile is 10.0 kN / m 3 ~11.0 kN / m 3 。

[0017] Correspondingly, the present invention also provides a construction method for aluminum ash residue-based lightweight mixing piles, including the following steps:

[0018] (1) According to the addition amounts of cement and secondary aluminum ash being 10% - 15% and 5% - 10% of the weight of soft clay respectively, weigh the cement and secondary aluminum ash, and sequentially add the weighed cement and secondary aluminum ash into water, control the water-cement ratio to be 0.45 - 0.55, and stir evenly to obtain a lightweight solidified slurry;

[0019] (2) Use a mixing pile construction machine to stir the lightweight solidified slurry and the soft clay in the soft foundation to form aluminum ash residue-based lightweight mixing piles in the soft foundation.

[0020] As an improvement of the above technical solution, step (2) includes the following steps:

[0021] (2.1) Move the mixing pile machine to the designated pile position and align it, start the mixing pile construction machine, and make the mixing pile construction machine stir while sinking;

[0022] (2.2) After the mixing pile construction machine sinks to the design depth, make the mixing pile construction machine spray the slurry, and while spraying and stirring, lift the mixing pile construction machine at the lifting speed determined by the design to mix the lightweight solidified slurry and the soft clay;

[0023] (2.3) Conduct repeated stirring to fully mix the lightweight solidified slurry and the soft clay to form aluminum ash residue-based lightweight mixing piles in the foundation.

[0024] Implementing the present invention has the following beneficial effects:

[0025] 1. The chemical composition of secondary aluminum ash contains 15% - 25% of AlN. When AlN encounters water, it will undergo a hydration reaction to generate ammonia. Utilizing this compositional characteristic of secondary aluminum ash, using it as the main raw material and collaborating with cement to make a lightweight solidified slurry, and using it to treat the soft foundation to form mixing piles can make the mixing piles have a porous structure, form drainage channels inside the mixing piles, improve the permeability of the foundation, accelerate the drainage rate, quickly drain the water in the soft foundation, be beneficial to the formation of the early strength of the pile body, and at the same time enable the foundation to be in a good working environment. Moreover, due to the porous characteristics of the mixing pile body, the pile body has a certain compressibility, which can coordinate the deformation between the pile body and the soil between piles under the action of load, effectively improving the problems of uneven settlement and differential settlement of the foundation. In addition, the porous structure also reduces the self-weight of the aluminum ash residue-based lightweight mixing pile, indirectly improving the ability of the foundation to bear the overlying load.

[0026] 2. An innovative construction method for aluminum ash-based lightweight mixing piles with both load-bearing and drainage functions is developed. The construction method of the aluminum ash-based lightweight mixing piles of the present invention makes full use of the compositional characteristics of secondary aluminum ash to achieve water-induced foaming, thereby enabling the mixing piles to obtain a porous structure. Based on the porous structure of the aluminum ash-based lightweight mixing piles, they can serve as drainage channels, accelerating the drainage rate, increasing the effective stress between soil particles, and facilitating the formation of foundation strength. At the same time, the self-weight of the mixing piles formed by the construction method of the present invention is light, which can improve the ability of the foundation to bear the overlying load. In addition, the construction method of the present invention can achieve the dual goals of harmless treatment of secondary aluminum ash and resource utilization of solid waste, greatly solving the pollution problem of secondary aluminum ash and contributing to environmental improvement. The aluminum ash-based lightweight mixing piles made by the construction method of the present invention expand the application scenarios of lightweight cementitious materials and enhance the application added value of industrial solid waste, having great engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a graph showing the unconfined compressive strength test results of the aluminum ash-based lightweight mixing piles formed in Examples 1 to 6 of the present invention;

[0028] Figure 2 It is a graph showing the permeability coefficient test results of the aluminum ash-based lightweight mixing piles formed in Examples 1 to 6 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0030] For those technical or conditions not specified in the embodiments, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For the raw materials not indicating the manufacturers, they are all conventional products that can be obtained through market purchase.

[0031] The present invention discloses an aluminum ash-based lightweight mixing pile, and the aluminum ash-based lightweight mixing pile is a porous structure formed by mixing a lightweight solidified slurry and soft clay;

[0032] The raw materials of the lightweight solidified slurry include cement and secondary aluminum ash, and the addition amounts of the cement and the secondary aluminum ash are respectively 10% - 15% and 5% - 10% of the weight of the soft clay;

[0033] Calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 15% - 25% of AlN;

[0034] It should be noted that the chemical composition of secondary aluminum ash contains 15% - 25% of AlN. When AlN encounters water, it will undergo a hydration reaction to generate ammonia. Utilizing this component characteristic of secondary aluminum ash, it is used as the main raw material and acts synergistically with cement to make a lightweight solidified slurry, which is used to treat soft foundations. The lightweight solidified slurry is mixed and stirred with soft clay to form an aluminum ash slag-based lightweight mixing pile with a porous structure, enabling the mixing pile to have a porous structure and forming drainage channels inside the mixing pile, which can improve the permeability of the foundation, accelerate the drainage rate, quickly drain the water in the soft foundation, facilitate the formation of the early strength of the pile body, and at the same time keep the foundation in a good working environment. Moreover, due to the porous characteristics of the mixing pile body, the pile body has a certain compressibility, which can coordinate the deformation between the pile body and the soil between piles under the action of load, and greatly improve the problems of uneven settlement and differential settlement of the foundation.

[0035] Furthermore, it is further explained that by controlling the addition amounts of cement and secondary aluminum ash in the lightweight solidified slurry to be 10% - 15% and 5% - 10% of the weight of the soft clay respectively, the strength of the mixing pile can be guaranteed, and at the same time, the permeability and compressibility of the mixing pile can be effectively improved.

[0036] Specifically, the addition amount of cement in the lightweight solidified slurry is exemplarily 10%, 11%, 12%, 13%, 14%, 15% of the weight of the soft clay, but not limited thereto. The addition amount of secondary aluminum ash in the lightweight solidified slurry is exemplarily 5%, 6%, 7%, 8%, 9%, 10% of the weight of the soft clay, but not limited thereto.

[0037] Specifically, aluminum ash is a solid waste generated during the production process of metallic aluminum or aluminum alloy through molten salt electrolysis, casting processing, and recycling. According to different sources, aluminum ash is usually divided into primary aluminum ash and secondary aluminum ash. Among them, secondary aluminum ash is the waste after extracting metallic aluminum from primary aluminum ash or the aluminum-containing waste residue generated during the aluminum refining process. The color of secondary aluminum ash is black, also known as black ash. The main components of secondary aluminum ash are aluminum oxide and aluminum nitride, and also contain some other oxides, as well as a small amount of chemical components such as fluoride salts, chloride salts, and trace metals. At present, the main treatment methods for secondary aluminum ash slag mainly adopt landfill or stacking treatment. The landfill or stacking method not only causes waste of resources but also brings problems such as occupation of land resources, groundwater pollution, and environmental hazards. The present invention utilizes the component characteristics of secondary aluminum ash to enable the mixing pile to obtain a porous structure, which can realize the harmless treatment of secondary aluminum ash and the resource utilization of solid waste, and largely solve the pollution problem of secondary aluminum ash, contributing to environmental improvement.

[0038] Preferably, the cement of the present invention is selected as ordinary Portland cement.

[0039] In one embodiment, by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% Al2O3, 15% - 25% AlN, 5% - 10% SiO2, 3% - 8% CaO, 1% - 5% MgO, 0.5% - 5% Fe2O3, chloride salts ≤ 2%, fluoride salts ≤ 2%, and other impurities 1% - 5%. Since the main component of the secondary aluminum ash is Al2O3 and it also contains a certain amount of SiO2, when preparing the mixing pile, the secondary aluminum ash can not only play a foaming role, but also be used as an aggregate and can reduce the amount of cement to a certain extent, thereby reducing the material cost. Moreover, the high content of Al2O3 in the secondary aluminum ash is beneficial to improving the mechanical properties and durability of the pile body. The secondary aluminum ash contains 3% - 8% CaO. When treating the soft foundation to form a mixing pile, CaO will react with water, which will not only consume part of the water, but also release heat during the reaction of CaO and water to form calcium hydroxide, increasing the surrounding environmental temperature, accelerating the curing rate of the cement, and further enhancing the early strength of the cement. In addition, the contents of chloride salts and fluoride salts in the secondary aluminum ash of the present invention are relatively low, both ≤ 2%, which can reduce the negative impact of chloride salts and fluoride salts on the strength of the mixing pile and reduce the corrosion effect of chloride ions and fluoride ions, being beneficial to enhancing the pile body strength, corrosion resistance, and durability.

[0040] Specifically, the chloride salts include NaCl, KCl, MgCl2, etc., the fluoride salts include NaF, KF, CaF2, etc., and the other impurities include carbon (C), titanium compounds (such as TiO2), metallic aluminum (Al), and other trace metals (such as Cu, Zn, Pb, Cd, Cr, Ba, As, etc.).

[0041] More preferably, by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% Al2O3, 15% - 25% AlN, 5% - 10% SiO2, 3% - 8% CaO, 1% - 5% MgO, 0.5% - 5% Fe2O3, chloride salts 0 - 1%, fluoride salts 0 - 1%, and other impurities 1% - 5%. Selecting secondary aluminum ash with lower contents of chloride salts and fluoride salts in this embodiment is beneficial to further enhancing the pile body strength, corrosion resistance, and durability.

[0042] In one embodiment, the particle size of the secondary aluminum ash is 5 μm - 50 μm, and the average particle size is 10 μm - 15 μm.

[0043] By ball-milling the secondary aluminum ash to make its particle size 5 μm - 50 μm and the average particle size 10 μm - 15 μm, the specific surface area of the secondary aluminum ash can be increased, the hydration reaction rate of AlN can be accelerated, the generation amount of ammonia gas can be increased, and then the mixing pile can have a porous structure, improving the permeability and compressibility of the foundation.

[0044] In one embodiment, the water-cement ratio of the lightweight solidifying slurry is 0.45 to 0.55. Controlling the water-cement ratio within the range of 0.45 to 0.55 can endow the lightweight solidifying slurry with good pumping fluidity, and the formed mixing pile has relatively high strength.

[0045] Exemplarily, the water-cement ratio of the lightweight solidifying slurry is 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, but not limited thereto.

[0046] In one embodiment, the raw materials of the lightweight solidifying slurry further include a water reducing agent, and the addition amount of the water reducing agent is 0.1% to 0.8% of the weight of the soft clay. Under the condition of constant cement dosage, adding a water reducing agent can reduce the mixing water amount of the lightweight solidifying slurry, which is beneficial to improving the strength of the mixing pile.

[0047] Specifically, the addition amount of the water reducing agent is exemplarily 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% of the weight of the soft clay, but not limited thereto.

[0048] Preferably, the water reducing agent includes any one or a combination of polycarboxylate water reducing agents, melamine water reducing agents, and naphthalene water reducing agents.

[0049] Correspondingly, a construction method of an aluminum ash residue-based lightweight mixing pile is also disclosed, including the following steps:

[0050] (1) According to the addition amounts of cement and secondary aluminum ash being 10% to 15% and 5% to 10% of the weight of the soft clay to be treated respectively, weigh the cement and secondary aluminum ash, sequentially add the weighed cement and secondary aluminum ash into water, control the water-cement ratio to be 0.45 to 0.55, and stir evenly to obtain the lightweight solidifying slurry;

[0051] (2) Use a mixing pile construction machine (such as a mixing pile rig) to stir the lightweight solidifying slurry and the soft clay to form an aluminum ash residue-based lightweight mixing pile in the soft foundation.

[0052] The present invention innovatively develops a construction method for aluminum ash slag-based lightweight mixing piles with both load-bearing and drainage functions. The construction method of the aluminum ash slag-based lightweight mixing piles of the present invention makes full use of the composition characteristics of secondary aluminum ash to achieve water-induced foaming, thereby enabling the mixing piles to obtain a porous structure. Based on the porous structure of the aluminum ash slag-based lightweight mixing piles, they can serve as drainage channels, accelerating the drainage rate, increasing the effective stress between soil particles, and facilitating the formation of foundation strength. At the same time, it can achieve the dual goals of harmless treatment of secondary aluminum ash and resource utilization of solid waste. In addition, the self-weight of the mixing piles formed by the construction method of the present invention is light, which can improve the ability of the foundation to bear the overlying load. The aluminum ash slag-based lightweight mixing piles made by the construction method of the present invention expand the application scenarios of lightweight cementitious materials and enhance the application added value of industrial solid waste, having great engineering practical value.

[0053] Furthermore, it should be noted that the construction method of the aluminum ash slag-based lightweight mixing piles of the present invention is simple and can directly apply the construction technology and equipment of conventional mixing piles. In addition, on the premise of meeting the specific gravity of the aluminum ash slag-based lightweight mixing piles, the amount of cement can be further adjusted to ensure the strength of the aluminum ash slag-based lightweight mixing piles and meet the requirements of different foundations and loads.

[0054] It is worth noting that the specific gravity of the aluminum ash slag-based lightweight mixing piles formed by the construction method of the present invention is 10.0 kN / m 3 ~11.0 kN / m 3 ; within this specific gravity range, the specific gravity of the aluminum ash slag-based lightweight mixing piles is slightly greater than that of water, which can prevent the aluminum ash slag-based lightweight mixing piles from floating. At the same time, within this specific gravity range, it can maximally improve the ability of the aluminum ash slag-based lightweight mixing piles to bear the overlying load. In addition, the aluminum ash slag-based lightweight mixing piles formed by the present invention have a porous structure with through-drainage pores inside. These drainage pores are interconnected to form a drainage channel. The pore diameter of the drainage pores measured by mercury intrusion test is 0.1 μm~1 μm. Within this pore diameter range, the aluminum ash slag-based lightweight mixing piles have moderate permeability and compressibility, and have a low impact on the strength of the aluminum ash slag-based lightweight mixing piles, ensuring that the strength of the aluminum ash slag-based lightweight mixing piles can meet the foundation requirements.

[0055] In one embodiment, the construction method of the present invention is used to treat soft clay with high water content and high compressibility. Specifically, the water content of the soft clay is 35%~75%, and the compression coefficient of the soft clay is ≥0.5 MPa -1 .

[0056] In one embodiment, step (2) includes the following steps:

[0057] (2.1) Pre-stir and sink: Move the mixing pile machine to the designated pile position and align it. Start the motor of the mixing pile construction machine to make the mixing pile construction machine stir while sinking.

[0058] (2.2) Lift and spray mixing: After the mixing pile construction machine sinks to the design depth, turn on the mortar pump to make the mixing pile construction machine spray mortar. After the mortar comes out of the mixing pile construction machine, lift the mixing pile construction machine while spraying and mixing at the lifting speed determined by the design (such as 0.5 m / min to 0.8 m / min) to mix the lightweight solidified slurry and soft clay.

[0059] (2.3) Conduct repeated mixing to fully mix the lightweight solidified slurry and soft clay to form an aluminum ash slag-based lightweight mixing pile in the foundation.

[0060] Further explanation, in actual foundation treatment, after constructing one mixing pile, the mixing pile construction machine needs to be moved to the next pile position, and step (2) is repeated to construct the next pile body. After all the mixing pile construction operations are completed, check the pile head elevation and conduct the site leveling operation before subgrade construction. Then, conduct subgrade filling on the formed aluminum ash slag-based lightweight mixing pile composite foundation.

[0061] Specifically, the construction method of the aluminum ash slag-based lightweight mixing pile of the present invention adopts the two-spray and four-mixing process. Preferably, when drilling down for the first time, in order to avoid pipe blockage, it can be drilled with slurry, and the spraying volume should be less than 1 / 2 of the total amount. It is strictly prohibited to drill with water. Low gear operation is adopted for both the first time of drilling down and lifting the drill. One gear can be increased during re-mixing. The normal pile forming time for each pile should be no less than 40 minutes, and the spraying pressure should not be less than 0.4 MPa.

[0062] Preferably, in order to ensure the quality of the pile end, pile top and pile body of the aluminum ash slag-based lightweight mixing pile, when lifting the drill and spraying mortar for the first time, it should stay at the bottom of the pile for 30 seconds to grind the pile end, and all the remaining mortar should be sprayed into the pile body during the upward movement, and the pile head should be ground at the pile top position for 30 seconds.

[0063] Preferably, a mixing head with "peripheral edge spraying" is adopted during the mixing pile construction process. The spraying port of this mixing head is located at the outermost edge of the mixing blade. When the slurry moves from the blade to the central annular space of the pile body, with the rotation and cutting of the blade, the slurry can be evenly distributed in the soil in the pile body. Long-term use has proved that the mixing head with "peripheral edge spraying" can better solve the problem of uneven mixing during spraying.

[0064] The present invention's aluminum ash slag-based lightweight mixing pile construction method fully utilizes secondary aluminum ash, an industrial solid waste, and applies it to the construction process of cement-soil mixing piles. The secondary aluminum ash is mixed with cement slurry to form aluminum ash slag-based lightweight mixing piles. This, combined with the existing foundation, forms an aluminum ash slag-based lightweight mixing pile composite foundation. Because the aluminum ash slag-based lightweight mixing piles inherently possess a certain strength, the resulting new aluminum ash slag-based lightweight mixing pile composite foundation has a bearing capacity roughly equivalent to that of conventional composite foundations. Based on the characteristics of secondary aluminum ash, the following technical problems can be effectively solved: First, the pile body has a light weight, which can greatly reduce the weight of the composite foundation during casting and forming, which on the other hand also improves the ability of the foundation to bear the overlying load; Second, the pile body itself has a certain compressibility. Under the action of load, the deformation difference between the pile body and the soil between the piles can be coordinated, which can largely solve the problems of uneven settlement and differential settlement; Third, the aluminum ash slag-based lightweight mixing pile has a porous structure inside, which improves the permeability of the foundation, can accelerate foundation drainage, and is conducive to the formation of early strength of the pile body, while also allowing the foundation to be in a good working environment.

[0065] The technical solution of the present invention is further described below through examples.

[0066] Example 1

[0067] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles, comprising the following steps:

[0068] (1) Cement, secondary aluminum ash, and water reducer are weighed according to the amount of cement, secondary aluminum ash, and water reducer added, which are 10%, 5%, and 0.5% of the weight of the soft clay to be treated, respectively; water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to be 0.45. After fully stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry;

[0069] The chemical composition of secondary aluminum ash, calculated by mass percentage, includes Al2O3 58.7%, AlN 19.4%, SiO2 8.2%, CaO 6.3%, MgO 2.5%, Fe2O3 1.7%, chloride 0.5%, fluoride 0.4%, and other impurities 2.3%. The particle size of secondary aluminum ash is 5μm to 50μm, with an average particle size of 13.2μm.

[0070] (2) The lightweight solidified slurry and the soft clay in the soft foundation are mixed by a mixing pile construction machine to form an aluminum ash slag-based lightweight mixing pile in the soft foundation. The water content of the soft clay to be treated in this embodiment is 52%, and the compression coefficient of the soft clay is 0.9 MPa. -1 The mixing pile construction machine used in this embodiment is a mixing pile machine; specifically, step (2) includes the following steps:

[0071] (2.1) Pre-mixing and sinking: Move the pile mixer to the designated pile position and align it, start the motor of the pile mixer, and allow the pile mixer to sink and mix at the same time;

[0072] (2.2) Lifting and spraying: After the mixer sinks to the designed depth, start the mortar pump and deliver the lightweight solidified slurry to the slurry outlet of the mixing head of the mixing pile machine through the pipeline. After the slurry is discharged, start the mixing pile machine and lift the mixing pile machine at the lifting speed determined by the design while spraying and mixing to ensure that the lightweight solidified slurry and soft clay are fully mixed;

[0073] (2.3) Repeated mixing: When the pile mixing machine is lifted to the designed height, the mortar pump is turned off and the pile is repeatedly stirred and sunk to the designed depth. When the pile sinks to the designed depth, the mortar is repeatedly stirred and lifted to the ground to mix the soft clay and the lightweight solidified slurry evenly, forming aluminum ash slag-based lightweight mixing piles in the foundation.

[0074] Example 2

[0075] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles. The construction method of Example 2 differs from that of Example 1 in that the amount of secondary aluminum ash added in Example 2 is 6% of the weight of the soft clay to be treated. That is, in step (1) of Example 2, cement, secondary aluminum ash, and water reducer are weighed according to the amounts of cement, secondary aluminum ash, and water reducer added, which are 10%, 6%, and 0.5% of the weight of the soft clay to be treated, respectively. Water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to 0.45. After thorough stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry.

[0076] Example 3

[0077] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles. The construction method of Example 3 differs from that of Example 1 in that the amount of secondary aluminum ash added in Example 3 is 7% of the weight of the soft clay to be treated. That is, in step (1) of Example 3, cement, secondary aluminum ash, and water reducer are weighed according to the amounts of cement, secondary aluminum ash, and water reducer added, which are 10%, 7%, and 0.5% of the weight of the soft clay to be treated, respectively. Water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to 0.45. After thorough stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry.

[0078] Example 4

[0079] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles. The construction method of Example 4 differs from that of Example 1 in that the amount of secondary aluminum ash added in Example 4 is 8% of the weight of the soft clay to be treated. That is, in step (1) of Example 4, cement, secondary aluminum ash, and water reducer are weighed according to the amounts of cement, secondary aluminum ash, and water reducer added, which are 10%, 8%, and 0.5% of the weight of the soft clay to be treated, respectively. Water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to 0.45. After thorough stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry.

[0080] Example 5

[0081] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles. The construction method of Example 5 differs from that of Example 1 in that the amount of secondary aluminum ash added in Example 5 is 9% of the weight of the soft clay to be treated. That is, in step (1) of Example 5, cement, secondary aluminum ash, and water reducer are weighed according to the amounts of cement, secondary aluminum ash, and water reducer added, which are 10%, 9%, and 0.5% of the weight of the soft clay to be treated, respectively. Water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to 0.45. After thorough stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry.

[0082] Example 6

[0083] This embodiment provides a construction method for aluminum ash slag-based lightweight mixing piles. The construction method of Example 6 differs from that of Example 1 in that the amount of secondary aluminum ash added in Example 6 is 10% of the weight of the soft clay to be treated. That is, in step (1) of Example 6, cement, secondary aluminum ash, and water reducer are weighed according to the amounts of cement, secondary aluminum ash, and water reducer added, which are 10%, 10%, and 0.5% of the weight of the soft clay to be treated, respectively. Water is added to a mixer, and the weighed cement and water reducer are added to the water, controlling the water-cement ratio to 0.45. After thorough stirring, the secondary aluminum ash is added and further stirred to obtain a lightweight solidified slurry.

[0084] Performance Testing:

[0085] After the aluminum ash slag-based lightweight mixing piles of Examples 1 to 6 were cured, core samples were drilled and the obtained samples were cured in a curing room at a constant temperature (20±2°C) and a constant humidity (95%) for 7 days, 28 days, and 60 days. The unconfined compressive strength and permeability coefficient of each sample were tested at 7 days, 28 days, and 60 days. The test results are shown in Table 1. Figure 1 and Figure 2 shown.

[0086] Table 1 Performance test data

[0087]

[0088] Figure 1 It is a graph of the unconfined compressive strength test results. Figure 2 It is a graph of the permeability coefficient test results. As can be seen from Table 1 and Figure 1 It can be seen that after 7 days of curing for Examples 1 - 6, a certain early strength can be formed, and as the addition amount of secondary aluminum ash increases, the 7-day unconfined compressive strength of the aluminum ash slag-based lightweight mixing pile gradually increases. Especially when the addition amount of secondary aluminum ash is 8% - 10% (i.e., Examples 4 - 6), the 7-day unconfined compressive strength of the aluminum ash slag-based lightweight mixing pile increases significantly. Thus, it can be seen that the addition of secondary aluminum ash can improve the permeability of the foundation, accelerate the drainage of the foundation, and is beneficial to the formation of the early strength of the pile body. From the unconfined compressive strength data at 7 days, 28 days, and 60 days, it can be known that increasing the curing time can further improve the unconfined compressive strength of the aluminum ash slag-based lightweight mixing pile. From Figure 2 It can be seen that when the doping amount of secondary aluminum ash is 5% - 9%, as the doping amount of secondary aluminum ash increases, the permeability coefficient of the aluminum ash slag-based lightweight mixing pile gradually increases. When the doping amount of secondary aluminum ash is 9% - 10%, the permeability coefficient of the aluminum ash slag-based lightweight mixing pile decreases somewhat.

[0089] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A lightweight mixing pile based on aluminum ash slag, characterized in that, The aluminum ash slag-based lightweight mixing pile is a porous structure made by mixing a lightweight solidifying slurry with soft clay; The raw materials of the lightweight solidifying slurry include cement and secondary aluminum ash, and the addition amounts of the cement and the secondary aluminum ash are respectively 10% - 15% and 5% - 10% of the weight of the soft clay; Calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 15% - 25% of AlN.

2. The light mixing pile based on aluminum ash residue according to claim 1, wherein Calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% of Al2O3, 15% - 25% of AlN, 5% - 10% of SiO2, 3% - 8% of CaO, 1% - 5% of MgO, 0.5% - 5% of Fe2O3, chloride salt ≤ 2%, fluoride salt ≤ 2% and other impurities 1% - 5%.

3. The light mixing pile based on aluminum ash slag according to claim 1, wherein Calculated by mass percentage, the chemical composition of the secondary aluminum ash includes 50% - 65% of Al2O3, 15% - 25% of AlN, 5% - 10% of SiO2, 3% - 8% of CaO, 1% - 5% of MgO, 0.5% - 5% of Fe2O3, chloride salt 0 - 0.5%, fluoride salt 0 - 0.5% and other impurities 1% - 5%.

4. The light mixing pile based on aluminum ash slag according to claim 1, wherein The water content of the soft clay is 35% to 75%, and the compression coefficient of the soft clay is ≥ 0.5 MPa -1 .

5. The light mixing pile based on aluminum ash slag according to claim 1, characterized in that, The particle size of the secondary aluminum ash is 5μm - 50μm, and the average particle size is 10μm - 15μm.

6. The light mixing pile based on aluminum ash residue according to claim 1, characterized in that, The water-cement ratio of the lightweight solidifying slurry is 0.45 - 0.

55.

7. The light mixing pile based on aluminum ash residue according to claim 1, wherein, The raw materials of the lightweight solidifying slurry further include a water reducing agent, and the addition amount of the water reducing agent is 0.1% - 0.8% of the weight of the soft clay.

8. The light mixing pile based on aluminum ash slag according to claim 1, characterized in that There are through drainage pores inside the porous structure of the aluminum ash slag-based lightweight mixing pile, and the pore diameter of the drainage pores is 0.1μm - 1μm; The unit weight of the lightweight mixing pile based on aluminum ash residue is 10.0 kN / m 3 to 11.0 kN / m 3 .

9. Construction method of an aluminum ash residue-based lightweight mixing pile, characterized in that, Used for preparing the aluminum ash slag-based lightweight mixing pile according to any one of claims 1 - 8 in the foundation, including the following steps: (1) According to the addition amounts of the cement and the secondary aluminum ash being respectively 10% - 15% and 5% - 10% of the weight of the soft clay, weigh the cement and the secondary aluminum ash, sequentially add the weighed cement and secondary aluminum ash into water, control the water-cement ratio to be 0.45 - 0.55, and stir evenly to obtain a lightweight solidifying slurry; (2) Use a mixing pile construction machine to mix the lightweight solidifying slurry with the soft clay in the soft foundation to form an aluminum ash slag-based lightweight mixing pile in the soft foundation.

10. The construction method of the aluminum ash slag-based lightweight mixing pile according to claim 9, characterized in that, Step (2) includes the following steps: (2.1) Move the mixing pile machine to the designated pile position and align it, start the mixing pile construction machine, and make the mixing pile construction machine stir while sinking; (2.2) After the mixing pile construction machine sinks to the design depth, make the mixing pile construction machine spray the slurry, and according to the lifting speed determined by the design, lift the mixing pile construction machine while spraying and stirring to mix the lightweight solidifying slurry and the soft clay; (2.3) Conduct repeated stirring to fully mix the lightweight solidifying slurry and the soft clay to form an aluminum ash slag-based lightweight mixing pile in the foundation.

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