Direct vat set solid waste foaming warm mixing agent as well as preparation method and application thereof

Abstract

The invention discloses a direct vat set solid waste foaming warm mixing agent as well as a preparation method and application thereof, belongs to the technical field of materials for road engineering, and provides the direct vat set solid waste foaming warm mixing agent which comprises 80-100 parts of red mud, 80-120 parts of a modified solution, 0.5-2 parts of sodium dodecyl benzene sulfonate and 15-35 parts of water. According to the application of the solid waste foaming warm-mixing agent in preparation of the warm-mixing asphalt mixture, the warm-mixing asphalt mixture is prepared from 85-95 parts of aggregate, 4-6 parts of asphalt, 2-5 parts of filler and 0.5-2 parts of the solid waste foaming warm-mixing agent. The characteristics of porosity, strong water absorption and the like of the industrial solid waste red mud are utilized, the solid waste foaming warm-mixing agent is prepared after the industrial solid waste red mud is modified, the warm-mixed asphalt mixture is prepared in a direct feeding mode, more red mud is consumed while the pavement performance of the mixture is guaranteed, and resource utilization of the solid waste is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering materials, and in particular relates to a direct-cast solid waste foaming warm mix agent and a preparation method and application thereof. Background Art

[0002] At present, the mainstream hot mix asphalt (HMA) used for asphalt pavement construction has high mixing temperature, high energy consumption and large emissions. Excessive construction temperature will also cause asphalt aging, thus affecting pavement performance. Warm mix asphalt (WMA) technology can reduce the construction temperature of HMA by 30 to 60°C, so WMA technology will be an effective way to reduce carbon emissions and extend the construction time. The three existing WMA technologies all rely on warm mix agents. Among them, foaming and viscosity reduction technology has been widely promoted due to the low cost of warm mix agents. However, the foaming effect of water foaming and some water-containing mineral foaming warm mix agents has a limited duration, and it is easy to form residual water, which makes the mixture's low-temperature performance and water stability poor, resulting in premature disease of warm mix asphalt pavement, which has an adverse impact on transportation and driving safety.

[0003] Red mud is a solid waste material discharged from the aluminum industry, with an annual emission of up to one million tons. It is currently mainly used in three aspects. The first is the recovery of valuable metals. The second is to add it to building materials such as cement, microcrystalline glass, concrete, bricks, etc. The third is to apply it to the field of environmental remediation, such as using its porous structure to absorb harmful gases and use it as a desulfurizer. However, the consumption of red mud in these fields is relatively small, and due to technical limitations, the utilization rate of red mud is low. Red mud has been applied to HMA technology, but there are few reports on the application of red mud in WMA technology.

[0004] In the existing invention patents, red mud is used to prepare warm mix agents, and foamed asphalt is prepared by foaming hydrated minerals. However, due to the limitations of the structure and composition of red mud itself, it needs to be compounded with other materials. For example, CN109626872B discloses a foamed asphalt warm mix agent compounded with red mud and boron mud. In CN116254005B, natural zeolite is compounded with red mud to prepare a warm mix agent, and the alkalinity of red mud is used to modify the natural zeolite and enhance the foaming properties. Since the inventions of these two warm mix agents rely on compounding and the foaming matrix is ​​not entirely red mud, the red mud foaming WMA technology has not been fully realized. In addition, existing research is limited to the foaming properties of foamed asphalt, and it has not been put into asphalt mixture for WMA technology testing. Therefore, the performance of warm mix asphalt mixture, especially in low temperature and water stability, is still unknown. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a direct-injection solid waste foaming warm-mix agent and its preparation method and application. The solid waste foaming warm-mix agent is prepared by modifying the industrial solid waste red mud, utilizing its porous and strong water absorption properties. The warm-mix asphalt mixture is prepared by direct injection, which consumes more red mud while ensuring the road performance of the mixture, thereby realizing the resource utilization of solid waste.

[0006] To achieve the above-mentioned purpose, the present invention provides a direct-injection solid waste foaming warm-mix agent, which is prepared by the following raw materials in parts by weight: 80-100 parts of red mud, 80-120 parts of modified solution, 0.5-2 parts of sodium dodecylbenzene sulfonate, and 15-35 parts of water.

[0007] Preferably, the method comprises the following raw materials in parts by weight: 80-100 parts of red mud, 100-110 parts of modified solution, 1-1.5 parts of sodium dodecylbenzene sulfonate, and 20-30 parts of water.

[0008] Preferably, the red mud is sintered red mud.

[0009] Preferably, the modified solution is an alkaline solution, the concentration of the alkaline solution is 0.08-0.12 mol / L, and the alkaline solution is a potassium hydroxide solution and / or a sodium hydroxide solution.

[0010] The present invention also provides a method for preparing the solid waste foaming warm mix agent, comprising the following steps:

[0011] (1) Red mud is initially dried, ground and then dried to obtain red mud powder;

[0012] (2) mixing the red mud powder obtained in step (1) with the modified solution, reacting, filtering, and performing a first drying treatment to obtain modified red mud powder;

[0013] (3) mixing the modified red mud powder obtained in step (2) with sodium dodecylbenzene sulfonate and water to obtain a solid mixture; and shearing the mixture to obtain a solid waste foaming warm mix agent.

[0014] Preferably, the temperature of the preliminary drying in step (1) is 90-120°C, and the time of the preliminary drying is 2-4 hours; the grinding in step (1) is ball milling, and the grinding time is 30-60 minutes; the temperature of the re-drying in step (1) is 90-120°C, and the time of the re-drying is 2-4 hours; the particle size of the red mud powder in step (1) is ≤0.075mm; the reaction time in step (2) is 5-10 minutes; the temperature of the first drying in step (2) is 90-120°C, and the time of the first drying is 2-4 hours.

[0015] Preferably, the shearing speed in step (3) is 800 to 1500 rpm, and the shearing time is 5 to 10 min.

[0016] The present invention also provides the use of the solid waste foaming warm mix agent in preparing warm mix asphalt mixture.

[0017] Preferably, the warm-mix asphalt mixture is prepared by including the following raw materials in parts by weight: 85-95 parts of aggregate, 4-6 parts of asphalt, 2-5 parts of filler, and 0.5-2 parts of solid waste foaming warm-mix agent.

[0018] Preferably, the method for preparing the warm mix asphalt mixture comprises the following steps:

[0019] A. Heat the asphalt at 130-160℃ for 1-2h to obtain melted asphalt, and preheat the aggregate and filler at 160-180℃ for 2-4h to obtain preheated aggregate and preheated filler;

[0020] B. Add melted asphalt to the preheated aggregate obtained in A, and immediately add solid waste foaming warm mix agent to the surface for mixing, mix for the first time, and obtain a mixture; add the preheated filler obtained in A to the mixture, mix for the second time, and obtain a warm mix asphalt mixture.

[0021] Preferably, the temperature of the first mixing in step B is 120-150°C; the temperature of the second mixing in step B is 120-150°C.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] The present invention utilizes the porous structure and superior water absorption and water retention capacity of sintered red mud, further optimizes its structure through a modifier, prepares a direct-injection modified red mud solid waste foaming warm mix agent, and further improves the foaming performance through a surfactant. At the same time, the main component of the red mud, aluminosilicate, is used to further reduce the viscosity of asphalt, thereby achieving warm mixing. In addition, the red mud is finally left in the mixture as a filler, and the strong physical adsorption of Al2O3 on the light components of asphalt can improve the water damage resistance of the mixture.

[0024] The innovation of the present invention lies in that it utilizes the porous structure and strong water absorption and adsorption of sintered red mud, further optimizes its pore structure and performance through chemical modification, and then prepares a direct-cast solid waste foaming warm-mix agent, so that the warm-mix agent uses solid waste material red mud as the foaming matrix, providing a new consumption method for red mud solid waste. During the mixing process of the mixture, the water in the warm-mix agent evaporates due to heat and combines with asphalt, which promotes the foaming of asphalt and has a viscosity-reducing effect. After the mixing is completed, the main component of the warm-mix agent, red mud, restores its porous structure, absorbs asphalt, and enhances the bonding ability between asphalt and aggregate, avoiding adverse effects on the performance of the asphalt mixture.

[0025] Since the warm mix agent of the present invention can be directly added, the preparation process of the warm mix asphalt mixture is simple. In addition, the main component of the warm mix agent, red mud, can eventually be used as a filler and replace part of the mineral powder in the mixture, and the pore structure and performance of the red mud can be used to enhance the adsorption between the filler and the asphalt, improve the asphalt-aggregate adhesion, and improve the water stability and low temperature performance of the warm mix asphalt mixture.

[0026] Another advantage of the present invention is that the direct-injection solid waste foaming warm mix agent can replace high-priced warm mix agents such as organic viscosity reducers and chemical additives, reducing the capital investment in warm mix agents for warm mix asphalt mixtures. Selecting solid waste red mud as the foaming matrix not only reduces costs itself, but also red mud can replace part of the mineral powder, reducing the use of mineral resources. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0030] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0031] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0032] Unless otherwise specified, the "parts" described in the present invention are all based on mass parts.

[0033] Sources of materials used in the present invention: sintered red mud comes from Shandong Aluminum Co., Ltd.; No. 70 matrix asphalt is provided by Shandong Chambroad Holding Group Co., Ltd.; and all reagents used are commercially available analytically pure reagents.

[0034] Example 1

[0035] Solid waste foaming warm mix agent: 85 parts of sintered red mud, 100 parts of 0.1 mol / L sodium hydroxide solution, 1 part of sodium dodecylbenzene sulfonate, and 25 parts of water (municipal tap water).

[0036] (1) The sintered red mud was initially dried at 110°C for 3 h, ball-milled for 45 min, and then dried at 110°C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0037] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 6 min to allow the chemical reaction to proceed fully, and then filtered and dried at 110° C. for 3 h to obtain modified red mud powder;

[0038] (3) The modified red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 6 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1200 rpm for 8 minutes to obtain a solid waste foaming warm mix agent.

[0039] Warm mix asphalt mixture (type AC20): 90 parts of aggregate, 5.1 parts of asphalt, 3 parts of filler, 1.2 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0040] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0041] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and immediately add solid waste foaming warm mix agent to the surface for mixing. This will facilitate the solid waste foaming warm mix agent to adhere evenly to the hot asphalt and improve the foaming effect. Mix it evenly at 130°C for the first time to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C for the second time to obtain a warm mix asphalt mixture.

[0042] Example 2

[0043] Solid waste foaming warm mix agent: 90 parts of sintered red mud, 110 parts of 0.1 mol / L sodium hydroxide solution, 1.5 parts of sodium dodecylbenzene sulfonate, and 30 parts of water (municipal tap water).

[0044] (1) The sintered red mud was initially dried at 120°C for 2 h, ball-milled for 60 min, and then dried at 120°C for 1 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0045] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 8 min to allow the chemical reaction to proceed fully, and then filtered and dried at 120° C. for 2 h to obtain modified red mud powder;

[0046] (3) The modified red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 8 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1500 rpm for 5 minutes to obtain a solid waste foaming warm mix agent.

[0047] Warm mix asphalt mixture (type AC20): 88 parts of aggregate, 4.8 parts of asphalt, 2.4 parts of filler, 1.8 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0048] (1) The asphalt is heated at 140°C for 2 hours to obtain melted asphalt, and the aggregate and filler are preheated at 180°C for 3.5 hours to obtain preheated aggregate and preheated filler;

[0049] (2) Preheat the aggregate to 120°C and mix evenly, add melted asphalt to the preheated aggregate, and immediately add solid waste foaming warm mix agent to the surface for mixing, so that the solid waste foaming warm mix agent can be evenly adhered to the hot asphalt to improve the foaming effect. Mix evenly at 120°C for the first time to obtain a mixture; add the preheated filler to the mixture, and mix evenly at 120°C for the second time to obtain a warm mix asphalt mixture.

[0050] Example 3

[0051] Solid waste foaming warm mix agent: 100 parts of sintered red mud, 80 parts of 0.1 mol / L sodium hydroxide solution, 0.6 parts of sodium dodecylbenzene sulfonate, and 18 parts of water (municipal tap water).

[0052] (1) The sintered red mud was initially dried at 90 °C for 2.5 h, ball-milled for 30 min, and then dried at 90 °C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0053] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 5 min to allow the chemical reaction to proceed fully, and then filtered and dried at 90° C. for 2.5 h to obtain modified red mud powder;

[0054] (3) The modified red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 5 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 800 rpm for 5 minutes to obtain a solid waste foaming warm mix agent.

[0055] Warm mix asphalt mixture (type AC20): 88 parts of aggregate, 4.8 parts of asphalt, 3.6 parts of filler, and 0.6 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0056] (1) The asphalt is heated at 160°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 180°C for 2 hours to obtain preheated aggregate and preheated filler;

[0057] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and immediately add solid waste foaming warm mix agent to the surface for mixing. This will facilitate the solid waste foaming warm mix agent to adhere evenly to the hot asphalt and improve the foaming effect. Mix it evenly at 130°C for the first time to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C for the second time to obtain a warm mix asphalt mixture.

[0058] Example 4

[0059] Solid waste foaming warm mix agent: 85 parts of sintered red mud, 100 parts of 0.1 mol / L sodium hydroxide solution, 1 part of sodium dodecylbenzene sulfonate, and 25 parts of water (municipal tap water).

[0060] (1) The sintered red mud was initially dried at 110°C for 3 h, ball-milled for 45 min, and then dried at 110°C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0061] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 6 min to allow the chemical reaction to proceed fully, and then filtered and dried at 110° C. for 3 h to obtain modified red mud powder;

[0062] (3) The modified red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 6 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1200 rpm for 8 minutes to obtain a solid waste foaming warm mix agent.

[0063] Warm mix asphalt mixture (type AC25): 90 parts of aggregate, 5.1 parts of asphalt, 3 parts of filler, 1.2 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0064] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0065] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and immediately add solid waste foaming warm mix agent to the surface for mixing. This will facilitate the solid waste foaming warm mix agent to adhere evenly to the hot asphalt and improve the foaming effect. Mix it evenly at 130°C for the first time to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C for the second time to obtain a warm mix asphalt mixture.

[0066] Example 5

[0067] Solid waste foaming warm mix agent: 85 parts of sintered red mud, 100 parts of 0.1 mol / L sodium hydroxide solution, 1 part of sodium dodecylbenzene sulfonate, and 25 parts of water (municipal tap water).

[0068] (1) The sintered red mud was initially dried at 110°C for 3 h, ball-milled for 45 min, and then dried at 110°C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0069] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 6 min to allow the chemical reaction to proceed fully, and then filtered and dried at 110° C. for 3 h to obtain modified red mud powder;

[0070] (3) The modified red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 6 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1200 rpm for 8 minutes to obtain a solid waste foaming warm mix agent.

[0071] Warm mix asphalt mixture (type AC25): 90 parts of aggregate, 5.1 parts of asphalt, 3 parts of filler, 1.2 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0072] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0073] (2) Preheat the aggregate to 120°C and mix evenly, add melted asphalt to the preheated aggregate, and immediately add solid waste foaming warm mix agent to the surface for mixing, so that the solid waste foaming warm mix agent can be evenly adhered to the hot asphalt to improve the foaming effect. Mix evenly at 120°C for the first time to obtain a mixture; add the preheated filler to the mixture, and mix evenly at 120°C for the second time to obtain a warm mix asphalt mixture.

[0074] Comparative Example 1

[0075] Solid waste foaming warm mix agent: 85 parts of sintered red mud, 100 parts of 0.1 mol / L sodium hydroxide solution, 1 part of sodium dodecylbenzene sulfonate, and 25 parts of water (municipal tap water).

[0076] (1) The sintered red mud was initially dried at 110°C for 3 h, ball-milled for 45 min, and then dried at 110°C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0077] (2) Red mud powder was mixed with sodium dodecylbenzene sulfonate and water, and stirred manually for 6 minutes to allow the chemical reaction to proceed fully, thereby obtaining a block-shaped and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1200 rpm for 8 minutes to obtain a solid waste foaming warm mix agent.

[0078] Warm mix asphalt mixture (type AC20): 90 parts of aggregate, 5.1 parts of asphalt, 3 parts of filler, 1.2 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0079] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0080] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and immediately add solid waste foaming warm mix agent to the surface for mixing. This will facilitate the solid waste foaming warm mix agent to adhere evenly to the hot asphalt and improve the foaming effect. Mix it evenly at 130°C for the first time to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C for the second time to obtain a warm mix asphalt mixture.

[0081] Comparative Example 2

[0082] Solid waste foaming warm mix agent: 85 parts of sintered red mud, 100 parts of 0.1 mol / L sodium hydroxide solution, and 25 parts of water (municipal tap water).

[0083] (1) The sintered red mud was initially dried at 110°C for 3 h, ball-milled for 45 min, and then dried at 110°C for 2 h to obtain red mud powder with a particle size of ≤ 0.075 mm. The initial drying and re-drying treatments were performed to remove excess moisture. The particle size after ball milling met the technical requirements for fillers in the Technical Specifications for Highway Asphalt Pavement Construction (JTG F40-2004).

[0084] (2) red mud powder was mixed with 0.1 mol / L sodium hydroxide solution, and the mixture was stirred manually for 6 min to allow the chemical reaction to proceed fully, and then filtered and dried at 110° C. for 3 h to obtain modified red mud powder;

[0085] (3) The modified red mud powder was mixed with water and stirred manually for 6 minutes to allow the chemical reaction to proceed fully, thereby obtaining a blocky and slightly moist solid mixture; a high-speed shearing machine was used to shear at a speed of 1200 rpm for 8 minutes to obtain a solid waste foaming warm mix agent.

[0086] Warm mix asphalt mixture (type AC20): 90 parts of aggregate, 5.1 parts of asphalt, 3 parts of filler, 1.2 parts of solid waste foaming warm mix agent. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTGF40-2004).

[0087] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0088] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and immediately add solid waste foaming warm mix agent to the surface for mixing. This will facilitate the solid waste foaming warm mix agent to adhere evenly to the hot asphalt and improve the foaming effect. Mix it evenly at 130°C for the first time to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C for the second time to obtain a warm mix asphalt mixture.

[0089] Comparative Example 3

[0090] Warm mix asphalt mixture (type AC20): 90 parts of aggregate, 5.1 parts of asphalt, and 3 parts of filler. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004).

[0091] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0092] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and mix it evenly at 130°C to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C to obtain a warm mix asphalt mixture.

[0093] Comparative Example 4

[0094] Warm mix asphalt mixture (type AC20): 90 parts of aggregate, 5.1 parts of asphalt, and 3 parts of filler. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004).

[0095] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0096] (2) Preheat the aggregate to 140°C and mix evenly, add melted asphalt to the preheated aggregate, mix evenly for the first time at 140°C to obtain a mixture; add the preheated filler to the mixture, mix evenly for the second time at 140°C to obtain a warm mix asphalt mixture.

[0097] Comparative Example 5

[0098] Warm mix asphalt mixture (type AC25): 90 parts of aggregate, 5.1 parts of asphalt, and 3 parts of filler. The aggregate is limestone, which meets the technical requirements for aggregate in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004). The asphalt is No. 70 base asphalt, and the filler is limestone mineral powder, which meets the technical requirements for filler in the "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004).

[0099] (1) The asphalt is heated at 150°C for 1.5 hours to obtain melted asphalt, and the aggregate and filler are preheated at 170°C for 3 hours to obtain preheated aggregate and preheated filler;

[0100] (2) Preheat the aggregate at 130°C and mix it evenly. Add melted asphalt to the preheated aggregate and mix it evenly at 130°C to obtain a mixture. Add the preheated filler to the mixture and mix it evenly at 130°C to obtain a warm mix asphalt mixture.

[0101] The performance tests were performed on the warm mix asphalt mixtures prepared in Examples 1 to 5 and Comparative Examples 1 to 5.

[0102] A. To evaluate the high temperature rutting resistance of warm mix asphalt mixture, an indoor wheel rolling test was conducted according to JTG E20-2011. The asphalt mixture rutting plates prepared in Examples 1 to 5 and Comparative Examples 1 to 5 with a size of 300 mm × 300 mm × 50 mm were compacted by a roller, and then placed in a constant temperature chamber at 60±1°C for 12 hours with the mold connected to ensure uniform heating. In the test, the contact pressure between the surface of the asphalt mixture and the surface of the test wheel was 0.7 MPa, and the tire was continuously reciprocated on the surface of the asphalt mixture at a rolling speed of 21 times / min for 1 hour, and the travel distance was 230±10 mm. The rutting depth was automatically collected by an LVDT displacement sensor, and the rutting deformations d1 and d2 at 45 min (t1) and 60 min (t2) were recorded respectively, and the dynamic stability of the mixture was calculated. Three parallel specimens were made for each warm mix asphalt mixture and the average value was taken. The higher the dynamic stability, the better the high temperature rutting resistance of the warm mix asphalt mixture.

[0103] B. Prepare the rutting plate specimens according to the method in A. After demoulding, use a high-precision cutting machine to cut the rutting plate into rectangular specimens (250mm×30mm×35mm). Then carry out low-temperature bending creep test on a universal testing machine. The test temperature is controlled at -10℃±0.5℃, and the specimens are kept at the preset temperature for 1h before the test officially starts. The loading rate of the testing machine is 50mm / min. According to the performance indicators of the specimens at failure, the bending and tensile strains at the bottom of the beams of different warm-mix asphalt mixture beam specimens are calculated. The average value of three parallel specimens is also used as the final result.

[0104] C: The water stability of warm mix asphalt mixture is evaluated by using the Marshall test. According to the requirements of T0702 in JTG E20-2011, the samples after 75 double-sided compaction are placed in water at 60±1℃ for 60min and 48h respectively. According to the difference between Marshall stability and Marshall stability after immersion, the residual stability after immersion is used as the key evaluation index and calculated by formula T 0709-2 in JTG E20-2011.

[0105] The results are shown in Table 1.

[0106] Table 1 Performance test results of warm mix asphalt mixtures prepared in Examples 1 to 5 and Comparative Examples 1 to 5

[0107]

[0108] From the performance test results in Table 1, it can be seen that:

[0109] (1) The warm-mix asphalt mixture prepared by the direct-injection solid waste foaming warm-mix agent of the present invention can reduce the mixing temperature by 20 to 30°C under the premise of meeting the "Technical Specifications for Highway Asphalt Pavement Construction". Therefore, it is feasible to use the modified sintered red mud as a matrix to prepare the water-containing mineral foaming warm-mix agent. If the warm-mix agent is not added or the non-modified sintered red mud is used to prepare the warm-mix asphalt mixture, its low-temperature cracking resistance and water stability are difficult to meet the requirements of the specification.

[0110] (2) The direct-injection solid waste foaming warm mix agent of the present invention not only reduces the mixing temperature, but also remains in the asphalt mixture as a filler, which is beneficial to improving the performance of the asphalt mixture, especially the low-temperature performance and water stability of the mixture. The use of red mud to prepare the warm mix agent consumes solid waste while ensuring the performance of the warm mix asphalt mixture and reducing the use of limestone powder, which has good economic and environmental benefits.

[0111] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A direct-injection solid waste foaming warm-mix agent, characterized in that: The invention is prepared by comprising the following raw materials in parts by weight: 80 to 100 parts of red mud, 80 to 120 parts of modified solution, 0.5 to 2 parts of sodium dodecylbenzene sulfonate and 15 to 35 parts of water.

2. The solid waste foaming warm mix agent according to claim 1, characterized in that: The invention is prepared by comprising the following raw materials in parts by weight: 80 to 100 parts of red mud, 100 to 110 parts of modified solution, 1 to 1.5 parts of sodium dodecylbenzene sulfonate and 20 to 30 parts of water.

3. The solid waste foaming warm mix agent according to claim 1 or 2, characterized in that: The red mud is sintered red mud.

4. The solid waste foaming warm mix agent according to claim 1 or 2, characterized in that: The modified solution is an alkaline solution, the concentration of the alkaline solution is 0.08-0.12 mol / L, and the alkaline solution is a potassium hydroxide solution and / or a sodium hydroxide solution.

5. The method for preparing the solid waste foaming warm mix agent according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Red mud is initially dried, ground and then dried to obtain red mud powder; (2) mixing the red mud powder obtained in step (1) with the modified solution, reacting, filtering, and performing a first drying treatment to obtain modified red mud powder; (3) mixing the modified red mud powder obtained in step (2) with sodium dodecylbenzene sulfonate and water to obtain a solid mixture; and shearing the mixture to obtain a solid waste foaming warm mix agent.

6. The method for preparing the solid waste foaming warm mix agent according to claim 5, characterized in that: The temperature of the preliminary drying in step (1) is 90-120°C, and the time of the preliminary drying is 2-4 hours; the grinding in step (1) is ball milling, and the grinding time is 30-60 minutes; the temperature of the re-drying in step (1) is 90-120°C, and the time of the re-drying is 2-4 hours; the particle size of the red mud powder in step (1) is ≤0.075mm; the reaction time in step (2) is 5-10 minutes; the temperature of the first drying in step (2) is 90-120°C, and the time of the first drying is 2-4 hours.

7. The method for preparing the solid waste foaming warm mix agent according to claim 5, characterized in that: The shearing speed in step (3) is 800-1500 rpm, and the shearing time is 5-10 min.

8. Use of the solid waste foaming warm mix agent according to any one of claims 1 to 4 in the preparation of warm mix asphalt mixture.

9. The use according to claim 8, characterized in that: The warm-mix asphalt mixture is prepared from the following raw materials in parts by weight: 85-95 parts of aggregate, 4-6 parts of asphalt, 2-5 parts of filler, and 0.5-2 parts of solid waste foaming warm-mix agent.

10. The use according to claim 9, characterized in that: The method for preparing the warm mix asphalt mixture comprises the following steps: A. Heat the asphalt at 130-160℃ for 1-2h to obtain melted asphalt, and preheat the aggregate and filler at 160-180℃ for 2-4h to obtain preheated aggregate and preheated filler; B. Add melted asphalt to the preheated aggregate obtained in A, and immediately add solid waste foaming warm mix agent to the surface for mixing, mix for the first time, and obtain a mixture; add the preheated filler obtained in A to the mixture, mix for the second time, and obtain a warm mix asphalt mixture.

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