Construction waste-based bridge abutment backfill material, preparation method and application thereof

Abstract

The application belongs to the technical field of highway bridge abutment backfill materials, and discloses a construction slag base bridge abutment backfill material, a preparation method and application thereof. The backfill material comprises the following raw materials in mass fractions: 1000-1400 parts of slag, 1500-2100 parts of slag base aggregate, 163-180 parts of granulated blast furnace slag powder, 50-123 parts of electronic sludge, 38-53 parts of desulfurization gypsum, 45-63 parts of alkali activator, 12-18 parts of quicklime, 1.3-1.8 parts of water reducing agent, 8-12 parts of aluminum paste, 1.7-2.5 parts of sodium alpha-alkyl sulfonate, 2.3-3.3 parts of polyacrylamide, 1-1.4 parts of ammonium stearate, and 1250-1750 parts of water. The backfill material fully utilizes solid wastes such as construction slag and electronic sludge, has the properties of light weight, water permeability and high strength, and is particularly suitable for bridge abutment backfill.

Description

Technical Field

[0001] This invention belongs to the technical field of backfill materials for highway bridge and culvert abutments, specifically relating to a backfill material for bridge abutments based on construction waste soil, its preparation method, and its application. Background Technology

[0002] The construction of infrastructure such as bridges requires a large amount of backfill material. The current trend is to utilize solid waste for backfilling, achieving environmental protection and efficient resource utilization, resulting in significant social and economic benefits. Similar research has been conducted both domestically and internationally. For example, Chinese invention patent CN108589540A, "A Method for Backfilling Bridge Abutments Using Coal Gangue," discloses a bridge abutment backfill material prepared by mixing calcined activated coal gangue and sand in a 7:3 volume ratio. This backfill material exhibits excellent mechanical properties and can replace some or all of the filler material. Chinese invention patent CN101857409A, "A Flowable Backfill Soil and its Preparation and Construction Method," discloses a bridge abutment backfill material prepared using cement, soil, and water. This backfill material features self-compacting properties, environmental friendliness, economy, and adjustable strength. Chinese invention patent CN115028404A, entitled "A Fluidized Fly Ash for Backfilling Bridge Abutments in Saline Soil Sections of Seasonally Frozen Zones, Its Preparation Method and Application," discloses a bridge abutment backfill material prepared using cement, fly ash, and water. This backfill material features fast construction speed, good fluidity, self-compacting properties, and is environmentally friendly and economical. The above technology effectively utilizes solid waste such as coal gangue and fly ash.

[0003] However, compared to solid wastes such as coal gangue and fly ash, the utilization of construction waste is more difficult. Coal gangue and other raw materials have relatively good quality, particularly high strength and good stability, while construction waste suffers from low strength and poor stability. From a performance perspective, unlike other backfill materials, abutment backfill materials require lightweight, permeable, and high-strength properties. However, these properties are difficult to harmonize when using construction waste. Achieving permeability and lightweight is extremely difficult with high waste volume, and achieving both high waste volume and high strength is difficult while still meeting the lightweight requirement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing a backfill material for bridge abutments based on construction waste, its preparation method and application. This backfill material makes full use of solid waste such as construction waste and electronic sludge, and has properties such as lightweight, permeability and high strength, making it particularly suitable for bridge abutment backfilling.

[0005] To address the technical problems proposed in this invention, this invention provides a backfill material for bridge abutments made from construction waste soil, comprising the following raw materials in parts by weight: 1000-1400 parts of construction waste soil, 1500-2100 parts of construction waste soil aggregate, 163-180 parts of granulated blast furnace slag powder, 50-123 parts of electronic sludge, 38-53 parts of desulfurized gypsum, 45-63 parts of alkali activator, 12-18 parts of quicklime, 1.3-1.8 parts of water-reducing agent, 8-12 parts of aluminum powder paste, 1.7-2.5 parts of sodium α-olefin sulfonate, 2.3-3.3 parts of polyacrylamide, 1-1.4 parts of ammonium stearate, and 1250-1750 parts of water.

[0006] In the above scheme, the particle size of the slag is ≤5mm and the moisture content is ≤5%.

[0007] In the above scheme, the particle size of the granulated blast furnace slag powder is ≤75μm and the activity index is ≥75%.

[0008] In the above scheme, the electronic sludge is sludge obtained after the electronic industry wastewater is treated by polyaluminum chloride flocculation and sedimentation, and its aluminum content is ≥25%, existing in an amorphous amorphous form.

[0009] In the above scheme, the electronic sludge has a pH of 2-5, an Al2O3 content of 30-60%, a SiO2 content of 10-20%, and a CaO content of 2-5%.

[0010] In the above scheme, the particle size of the electronic sludge is ≤75μm, the moisture content is ≤5%, and the specific surface area is ≤10m². 2 / g, with a porosity of 30-50%.

[0011] In the above scheme, the alkaline activator is one or more of sodium silicate, potassium silicate, and potassium sodium silicate, with a modulus of 1.2 to 1.5.

[0012] In the above scheme, the water-reducing agent is a powder water-reducing agent, specifically one or more of polycarboxylate water-reducing agents, naphthalene-based water-reducing agents, aliphatic water-reducing agents, and melamine-based water-reducing agents, with a water reduction rate ≥25%.

[0013] In the above scheme, the foaming ratio of the sodium α-olefin sulfonate is ≥50 times.

[0014] In the above scheme, the mass ratio of aluminum powder paste to sodium α-olefin sulfonate is (4.5~5):1.

[0015] In the above scheme, the particle size of the slag-based aggregate is ≤5mm.

[0016] In the above scheme, the particle size distribution of the slag-based aggregate is as follows: 5mm ≤ particle size < 2.5mm 40-60%, 2.5mm ≤ particle size < 1.25mm 20-30%, 1.25mm ≤ particle size < 0.63mm 10-15%, 0.63mm ≤ particle size < 0.315mm 5-10%, and particle size ≤ 0.315mm 5-10%, with a total of 100%.

[0017] In the above scheme, the preparation method of the slag-based aggregate includes the following steps:

[0018] 1) The slag is crushed and then calcined to obtain calcined slag powder;

[0019] 2) After mixing the electronic sludge with quicklime evenly, add calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum and mix evenly to obtain a mixture;

[0020] 3) Add the mixture and water to the granulator for granulation, and then cure and sieve to obtain the slag-based aggregate.

[0021] Furthermore, the calcination heating rate is 10-15℃ / min, the calcination temperature is 650-950℃, and the calcination time is 2-3h.

[0022] Furthermore, the particle size of the calcined slag powder is ≤75μm.

[0023] Furthermore, in step 2), the mass ratio of electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder, and desulfurized gypsum is 100:(16-80):(20-500):(24-120):(40-200).

[0024] Furthermore, in step 3), the mass of water is 15-30% of the mass of the mixture.

[0025] Furthermore, the granulator is a disc granulator with a disc inclination angle of 40-50° and a disc rotation speed of 40-60 rpm.

[0026] Furthermore, the curing temperature is 18–22℃, the humidity is ≥90%, and the time is 7–28 days.

[0027] This invention also provides a method for preparing backfill material for bridge abutments based on construction waste, comprising the following steps:

[0028] S1. Mix electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, and alkali activator evenly to obtain a solidifying agent solution;

[0029] S2. Sodium α-alkenyl sulfonate and a portion of water are mixed to obtain a foaming agent solution. The foaming agent solution and ammonium stearate are then added to a foaming machine to produce bubbles.

[0030] S3. After mixing the slag and quicklime, add the slag-based aggregate, aluminum powder paste, polyacrylamide, remaining water, curing agent solution and air bubbles and mix evenly. Finally, add the water-reducing agent and mix evenly to obtain the slag-based bridge abutment backfill material.

[0031] In the above scheme, in step S2, the mass ratio of sodium α-alkenylsulfonate to water is 1:(30-60).

[0032] This invention also provides an application of a construction waste-based bridge abutment backfill material in bridge abutment backfilling.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1) The backfill material prepared by the physicochemical synergistic gradient foaming process of this invention has a low density and is lighter than other backfill materials, resulting in less gravitational settlement and negligible lateral pressure on the abutment backfill. Traditional α-alkenyl sulfonate foaming is rapid but suffers from rapid collapse and poor stability. Aluminum powder paste foaming is a chemical reaction with a delayed effect, and the bubbles are low in density and easily escape. This invention is based on the fact that the foaming time of aluminum powder paste matches the foam half-life of sodium α-alkenyl sulfonate foaming agent. When the two are in a specific ratio, their foaming volumes are consistent. The gas obtained from the foaming of aluminum powder paste can fill the vacancies generated by the bursting of bubbles obtained from the foaming of sodium α-alkenyl sulfonate, thus improving the stability of the backfill material. At the same time, the bubbles formed by the foaming of sodium α-alkenyl sulfonate and the bubbles formed by the foaming of aluminum powder paste have significantly different densities and sizes. By controlling the viscosity of the slurry to achieve interlocking under gravity, it is also beneficial to the stability of the backfill material. In addition, the addition of nonionic surfactants as foam stabilizers adsorbs at the gas-liquid interface, reduces surface tension, and prevents the movement of the liquid film, thereby suppressing the phenomenon of bubble coalescence.

[0035] 2) The backfill material of this invention has good fluidity, high strength, and good permeability. This invention utilizes the charge neutralization and adsorption capacity of polyaluminum chloride in electronic sludge, which reduces the amount of polycarboxylate superplasticizer molecules adsorbed by the soil, thereby effectively improving the workability of the backfill soil. At the same time, electronic sludge has a large specific surface area and pore volume and diameter, belonging to porous materials. It is prepared together with calcined slag and slag powder to form slag-based porous aggregates with different gradations, ensuring the permeability of the backfill material. Moreover, the strength is provided by the NASH formed by calcined slag and the CASH formed by slag powder.

[0036] 3) This invention develops and uses a cement-free clinker-based slag solidifier. Through the synergistic effect of multiple components—electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, and alkali activator—the amount of CASH gel generated and the rate of Aft expansion source formation are precisely controlled. This not only achieves slag solidification but also solves the problem of slag drying and shrinkage cracking. When the electronic sludge content is too high, the excessively high active Al2O3 will cause the specimen to expand and crack rapidly; conversely, when the electronic sludge content is too low, the active Al2O3 decreases, reducing the generated Aft, which is insufficient to inhibit slag drying cracking. Therefore, the coordination between the components is crucial.

[0037] 4) The backfill material of this invention is economical and environmentally friendly. This invention uses solid waste raw materials such as slag, electronic sludge, granulated blast furnace slag powder, and desulfurization gypsum, which effectively utilizes solid waste resources, making the solid waste utilization rate reach more than 95%, reducing the accumulation of solid waste, reducing environmental pollution problems, improving the comprehensive utilization rate of solid waste, and reducing production costs, thus having good economic and social benefits. Detailed Implementation

[0038] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] In the following examples, the excavated soil was taken from the construction waste generated during construction in Hongshan District, Wuhan City. It was dried and crushed to make its particle size ≤5mm and moisture content ≤5%.

[0040] In the following examples, the electronic sludge was taken from a chip company in Jiangxia District, Wuhan City. It was obtained from wastewater generated during the chip manufacturing process after flocculation and sedimentation treatment with polyaluminum chloride. The sludge had a pH of 3, a SiO2 content of 15%, a CaCO3 content of 5%, an Al2O3 content of 45%, a particle size of ≤75μm, and a specific surface area of ​​≤10m². 2 / g, porosity 30%, moisture content ≤5%.

[0041] In the following examples, the particle size of the granulated blast furnace slag powder is ≤75μm and the activity index is ≥75%; the foaming ratio of sodium α-olefin sulfonate is 50 times.

[0042] In the following embodiments, the granulator is a disc granulator with a disc inclination angle of 45° and a disc rotation speed of 50 rpm.

[0043] Example 1

[0044] A backfill material for bridge abutments based on construction waste soil comprises the following raw materials in parts by weight: 1000 parts of construction waste soil, 1500 parts of construction waste soil aggregate, 163 parts of granulated blast furnace slag powder, 50 parts of electronic sludge, 38 parts of desulfurized gypsum, 45 parts of potassium sodium water glass with a modulus of 1.2, 12 parts of quicklime, 1.3 parts of aliphatic water-reducing agent with a water reduction rate of 25%, 8 parts of aluminum powder paste, 1.7 parts of sodium α-olefin sulfonate, 2.3 parts of polyacrylamide, 1 part of ammonium stearate, and 1250 parts of water.

[0045] The particle size distribution of the slag aggregate is as follows: 40% for particles 5mm ≤ size < 2.5mm, 30% for particles 2.5mm ≤ size < 1.25mm, 10% for particles 1.25mm ≤ size < 0.63mm, 10% for particles 0.63mm ≤ size < 0.315mm, and 10% for particles ≤ 0.315mm, with a total of 100%.

[0046] The preparation method of this slag-based aggregate includes the following steps:

[0047] 1) After crushing the slag, the temperature is raised to 650℃ at a heating rate of 10℃ / min and calcined for 2 hours to obtain calcined slag powder with a particle size ≤75μm.

[0048] 2) After mixing the electronic sludge and quicklime evenly, add calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum and mix evenly to obtain a mixture. The mass ratio of electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum is 100:16:20:24:40.

[0049] 3) Add the mixture and water to the granulator for granulation. The mass of water is 15% of the mass of the mixture. After granulation, cure for 28 days at a temperature of 20℃ and a humidity of ≥90%. Then sieve to obtain the above-mentioned slag-based aggregate with the particle size distribution.

[0050] The present invention discloses a method for preparing backfill material for bridge abutments made from construction waste, comprising the following steps:

[0051] S1. Mix electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, and potassium sodium water glass evenly to obtain a curing agent solution;

[0052] S2. Sodium α-alkenyl sulfonate and water are mixed at a mass ratio of 1:30 to obtain a foaming agent solution. The foaming agent solution and ammonium stearate are then added to a foaming machine to produce bubbles.

[0053] S3. After mixing the slag and quicklime, add the slag-based aggregate, aluminum powder paste, polyacrylamide, remaining water, curing agent solution and air bubbles and mix evenly. Finally, add the water-reducing agent and mix evenly to obtain the slag-based bridge abutment backfill material.

[0054] Example 2

[0055] A backfill material for bridge abutments based on construction waste soil comprises the following raw materials in parts by weight: 1400 parts of construction waste soil, 2100 parts of construction waste soil aggregate, 175 parts of granulated blast furnace slag powder, 123 parts of electronic sludge, 53 parts of desulfurized gypsum, 63 parts of potassium silicate with a modulus of 1.2, 18 parts of quicklime, 1.8 parts of naphthalene-based water-reducing agent with a water reduction rate of 25%, 12 parts of aluminum powder paste, 2.5 parts of sodium α-olefin sulfonate, 3.3 parts of polyacrylamide, 1.4 parts of ammonium stearate, and 1750 parts of water.

[0056] The particle size distribution of the slag-based aggregate is as follows: 60% for particles ≤ 5mm < 2.5mm, 20% for particles ≤ 1.25mm, 10% for particles ≤ 0.63mm, 5% for particles ≤ 0.63mm < 0.315mm, and 5% for particles ≤ 0.315mm, with a total of 100%.

[0057] The preparation method of this slag-based aggregate includes the following steps:

[0058] 1) After crushing the slag, the temperature is raised to 950℃ at a heating rate of 10℃ / min and calcined for 2 hours to obtain calcined slag powder with a particle size ≤75μm.

[0059] 2) After mixing the electronic sludge with quicklime evenly, add calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum and mix evenly to obtain a mixture. The mass ratio of electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum is 100:80:500:120:200.

[0060] 3) Add the mixture and water to the granulator for granulation. The mass of water is 30% of the mass of the mixture. After granulation, cure for 28 days at a temperature of 20℃ and a humidity of ≥90%. Then sieve to obtain the above-mentioned slag-based aggregate with the particle size distribution.

[0061] The present invention discloses a method for preparing backfill material for bridge abutments made from construction waste, comprising the following steps:

[0062] S1. Mix electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, and potassium water glass evenly to obtain a curing agent solution;

[0063] S2. Sodium α-alkenylsulfonate and water are mixed at a mass ratio of 1:60 to obtain a foaming agent solution. The foaming agent solution and ammonium stearate are then added to a foaming machine to produce bubbles.

[0064] S3. After mixing the slag and quicklime, add the slag-based aggregate, aluminum powder paste, polyacrylamide, remaining water, curing agent solution and air bubbles and mix evenly. Finally, add the water-reducing agent and mix evenly to obtain the slag-based bridge abutment backfill material.

[0065] Example 3

[0066] A backfill material for bridge abutments based on construction waste soil comprises the following raw materials in parts by weight: 1200 parts of construction waste soil, 1800 parts of construction waste soil aggregate, 180 parts of granulated blast furnace slag powder, 75 parts of electronic sludge, 45 parts of desulfurized gypsum, 54 parts of sodium silicate with a modulus of 1.2, 15 parts of quicklime, 1.5 parts of polycarboxylate superplasticizer with a water reduction rate of 35%, 10 parts of aluminum powder paste, 2.1 parts of sodium α-olefin sulfonate, 2.8 parts of polyacrylamide, 1.2 parts of ammonium stearate, and 1500 parts of water.

[0067] The particle size distribution of the slag aggregate is as follows: 5mm ≤ particle size < 2.5mm 50%, 2.5mm ≤ particle size < 1.25mm 25%, 1.25mm ≤ particle size < 0.63mm 10%, 0.63mm ≤ particle size < 0.315mm 5%, and particle size ≤ 0.315mm 10%, with a total of 100%.

[0068] The preparation method of this slag-based aggregate includes the following steps:

[0069] 1) After crushing the slag, the temperature is raised to 750℃ at a heating rate of 10℃ / min and calcined for 2 hours to obtain calcined slag powder with a particle size ≤75μm.

[0070] 2) After mixing the electronic sludge with quicklime evenly, add calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum and mix evenly to obtain a mixture. The mass ratio of electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum is 100:20:50:30:50.

[0071] 3) Add the mixture and water to the granulator for granulation. The mass of water is 20% of the mass of the mixture. After granulation, cure for 28 days at a temperature of 20℃ and a humidity of ≥90%. Then sieve to obtain the above-mentioned slag-based aggregate with the particle size distribution.

[0072] The present invention discloses a method for preparing backfill material for bridge abutments made from construction waste, comprising the following steps:

[0073] S1. Mix electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, and potassium sodium water glass evenly to obtain a curing agent solution;

[0074] S2. Sodium α-alkenylsulfonate and water are mixed at a mass ratio of 1:50 to obtain a foaming agent solution. The foaming agent solution and ammonium stearate are then added to a foaming machine to produce bubbles.

[0075] S3. After mixing the slag and quicklime, add the slag-based aggregate, aluminum powder paste, polyacrylamide, remaining water, curing agent solution and air bubbles and mix evenly. Finally, add the water-reducing agent and mix evenly to obtain the slag-based bridge abutment backfill material.

[0076] Example 4

[0077] A backfill material for bridge abutments based on construction waste soil comprises the following raw materials in parts by weight: 1300 parts of construction waste soil, 1950 parts of construction waste soil aggregate, 179 parts of granulated blast furnace slag powder, 98 parts of electronic sludge, 49 parts of desulfurized gypsum, 59 parts of sodium silicate and potassium silicate in a mass ratio of 2:1, 16 parts of quicklime, 1.6 parts of melamine-based water-reducing agent with a water reduction rate of 30%, 11 parts of aluminum powder paste, 2.3 parts of sodium α-olefin sulfonate, 3 parts of polyacrylamide, 1.3 parts of ammonium stearate, and 1630 parts of water.

[0078] The particle size distribution of the slag aggregate is as follows: 55% for particles ≤ 2.5mm, 20% for particles ≤ 1.25mm, 15% for particles ≤ 0.63mm, 5% for particles ≤ 0.63mm, and 5% for particles ≤ 0.315mm, with a total of 100%.

[0079] The preparation method of this slag-based aggregate includes the following steps:

[0080] 1) After crushing the slag, the temperature is raised to 850℃ at a heating rate of 10℃ / min and calcined for 2 hours to obtain calcined slag powder with a particle size ≤75μm.

[0081] 2) After mixing the electronic sludge with quicklime evenly, add calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum and mix evenly to obtain a mixture. The mass ratio of electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder and desulfurized gypsum is 100:40:200:60:100.

[0082] 3) Add the mixture and water to the granulator for granulation. The mass of water is 25% of the mass of the mixture. After granulation, cure for 28 days at a temperature of 20℃ and a humidity of ≥90%. Then sieve to obtain the above-mentioned slag-based aggregate with the particle size distribution.

[0083] The present invention discloses a method for preparing backfill material for bridge abutments made from construction waste, comprising the following steps:

[0084] S1. Mix electronic sludge, granulated blast furnace slag powder, desulfurized gypsum, sodium silicate, and potassium silicate evenly to obtain a curing agent solution;

[0085] S2. Sodium α-alkenylsulfonate and water are mixed at a mass ratio of 1:50 to obtain a foaming agent solution. The foaming agent solution and ammonium stearate are then added to a foaming machine to produce bubbles.

[0086] S3. After mixing the slag and quicklime, add the slag-based aggregate, aluminum powder paste, polyacrylamide, remaining water, curing agent solution and air bubbles and mix evenly. Finally, add the water-reducing agent and mix evenly to obtain the slag-based bridge abutment backfill material.

[0087] Comparative Example 1

[0088] The only difference between this comparative example and Example 3 is that this comparative example does not use slag-based aggregate. In order to ensure that the proportions of other components remain unchanged, 1800 parts of slag-based aggregate are replaced with 1800 parts of standard sand.

[0089] Comparative Example 2

[0090] The only difference between this comparative example and Example 3 is that this comparative example does not use electronic sludge. In order to ensure that the proportions of other components remain unchanged, 75 parts of electronic sludge are replaced with 75 parts of granulated blast furnace slag powder.

[0091] Performance testing

[0092] The workability consistency (flowability) and compressive strength and durability after backfilling of the bridge abutment backfill materials of Examples 1-4 and Comparative Examples 1-2 were tested.

[0093] (1) Consistency test: The test was conducted in accordance with the national standard GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures" to determine the flowability of the backfill material. Test mold: a truncated cone mold with an upper diameter of 36mm, a lower diameter of 60mm, a height of 60mm, and a smooth, seamless inner wall.

[0094] (2) Compressive strength test: The test was conducted in accordance with the national standard GB / T50123-2019 "Standard for Geotechnical Test Methods". The mixed mortar was poured into a six-piece mold with dimensions of 40mm×40mm×40mm and placed on a vibrating table for compaction for 1-2 minutes. After the mortar was compacted, the mold was placed in a constant temperature curing room (temperature 20±1℃, humidity 95±1%), and the surface was covered with a plastic film for curing. The compressive strength was tested at 7d and 28d.

[0095] (3) Permeability coefficient test: The permeability coefficient of the backfill material shall be determined in accordance with the standard CJJ / T135-2009 "Technical Specification for Permeable Cement Concrete Pavement".

[0096] (4) Dry density test: The dry density of the backfill material was determined in accordance with the national standard GB / T11969-2008 "Test Method for Performance of Autoclaved Aerated Concrete".

[0097] The test results are shown in the table below:

[0098]

[0099] As shown in the table above, the flowability of the construction waste-based bridge abutment backfill material prepared in this embodiment of the invention is 180–200 mm, the 7-day compressive strength is 2–3 MPa, the 28-day compressive strength is 5–6 MPa, the permeability coefficient is 0.6–0.8 mm / s, and the dry density is 700–800 kg / m³. 3 It has good fluidity, permeability and lightweight properties, and has high compressive strength after curing.

[0100] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A construction waste-based bridge abutment backfill material, characterized by, The raw materials include the following mass fractions: slag 1000-1400 parts, slag-based aggregate 1500-2100 parts, granulated blast furnace slag powder 163-180 parts, electronic sludge 50-123 parts, desulfurization gypsum 38-53 parts, alkali activator 45-63 parts, quicklime 12-18 parts, water reducing agent 1.3-1.8 parts, aluminum paste 8-12 parts, sodium alpha-alkenyl sulfonate 1.7-2.5 parts, polyacrylamide 2.3-3.3 parts, ammonium stearate 1-1.4 parts, and water 1250-1750 parts; the mass ratio of the aluminum paste to the sodium alpha-alkenyl sulfonate is (4.5-5):1; The preparation method of the slag-based aggregate comprises the following steps: 1) calcining the slag after crushing to obtain calcined slag powder; 2) uniformly mixing the electronic sludge with the quicklime, then adding the calcined slag powder, granulated blast furnace slag powder and desulfurization gypsum to mix uniformly to obtain a mixture; the mass ratio of the electronic sludge, quicklime, calcined slag powder, granulated blast furnace slag powder and desulfurization gypsum is 100:(16-80):(20-500):(24-120):(40-200); 3) granulating the mixture and water with a mass fraction of 15-30% of the mixture in a granulator, then curing and sieving to obtain the slag-based aggregate; The electronic sludge is sludge obtained after treating electronic industrial wastewater by polyaluminum chloride flocculation and sedimentation, and has a pH of 2-5 and an Al2O3 content of 30-60%.

2. The construction waste-based bridge abutment backfill material according to claim 1, characterized by, The calcination has a heating rate of 10-15 ℃ / min, a calcination temperature of 650-950 ℃ and a calcination time of 2-3 h; the calcined slag powder has a particle size of ≤75 μm.

3. The construction waste-based bridge abutment backfill material according to claim 1, characterized by, The particle size distribution of the slag-based aggregate is as follows: 2.5 mm≤particle size≤5 mm 40-60%, 1.25 mm≤particle size≤2.5 mm 20-30%, 0.63 mm≤particle size≤1.25 mm 10-15%, 0.315 mm≤particle size≤0.63 mm 5-10%, and particle size≤0.315 mm 5-10%, with a total amount of 100%.

4. The construction slurry-based bridge abutment backfill material of claim 1, wherein, The electronic sludge has a particle size of ≤75 μm, a water content of ≤5%, and a specific surface area of ≤10 m 2 / g, and a porosity of 30-50%; the residue has a particle size of ≤5 mm and a water content of ≤5%; and the granulated blast furnace slag powder has a particle size of ≤75 μm and an activity index of ≥75%.

5. The construction slurry-based bridge abutment backfill material of claim 1, wherein, The alkali activator is one or a composite of several of sodium water glass, potassium water glass and potassium-sodium water glass, and has a modulus of 1.2-1.5; the water reducing agent is one or a composite of several of polycarboxylic acid water reducing agent, naphthalene series water reducing agent, fatty water reducing agent and melamine series water reducing agent, and has a water reducing rate of ≥25%.

6. The construction slurry-based bridge abutment backfill material of claim 1, wherein, The sodium alpha-alkenyl sulfonate has a foaming ratio of ≥50 times.

7. A method of preparing a construction waste-based backfill material for bridge abutments according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: S1, uniformly mixing electronic sludge, granulated blast furnace slag powder, desulfurization gypsum and alkali activator to obtain a curing agent solution; S2, mixing sodium alpha-alkenyl sulfonate and part of water to obtain a foaming agent solution, then adding the foaming agent solution and ammonium stearate into a foaming machine to obtain bubbles; S3, uniformly mixing slag and quicklime, then adding slag-based aggregate, aluminum paste, polyacrylamide, the remaining water, the curing agent solution and the bubbles, and finally adding water reducing agent to obtain a building slag-based bridge abutment backfill material.

8. Use of the construction waste-based bridge abutment backfill material according to any one of claims 1 to 6 in the backfill of a bridge abutment.

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