Controllable low-strength backfill material modified by using building waste materials and shield muck and preparation method of controllable low-strength backfill material modified by using building waste materials and shield muck

Abstract

The invention discloses a controllable low-strength backfill material modified by building waste materials and shield muck and a preparation method, and belongs to the technical field of resource utilization of building engineering waste materials. According to the invention, the shield muck is used as a main raw material, and a certain amount of shield muck is replaced with the building waste material, so that the working performance of the controllable low-strength material is optimized. After the ratio of the shield muck to the building waste is determined, the use amount of the industrial waste residues, the cement, the water and the solid water glass is determined, the synergistic effect of all the materials is achieved by controlling the adding amount of the industrial waste residues and the solid water glass, and the synergistic improvement of the mechanical property of the controllable low-strength backfill material and the synergistic optimization of the working performance of the controllable low-strength backfill material are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of construction waste, and in particular relates to a controllable low-strength backfill material and a preparation method thereof that utilizes construction waste to coordinately modify shield slag. Background Art

[0002] At present, with the rapid development of urbanization and urban underground rail transit construction in my country and the continuous improvement of urban underground pipelines, the output of construction waste and shield slag is becoming increasingly large. At present, the technical level of the treatment industry for construction waste and shield slag is low and the scale is small. Most of them are disposed of by stacking and landfilling. Only a small part can be used as grouting material for concrete after screening. Large amounts of stacking waste urban development space and also bring great challenges to environmental protection. How to effectively treat and utilize them is a problem that needs to be solved urgently, which is of great significance to promoting resource reuse and sustainable development.

[0003] Controllable low-strength materials are cement-based low-strength backfill materials that can replace traditional backfill materials. This material has high fluidity and can fill itself under the influence of its own weight with only a small amount of vibration or even no vibration, thereby forming a self-compacting structure. Traditional controllable low-strength materials are usually mainly composed of cement, fine aggregates such as sand, coarse aggregates such as gravel, water reducers, admixtures, water, etc., and have poor economic and environmental benefits. The large-scale use of cement will have an adverse impact on the environment. Shield slag can replace fine aggregates such as sand, construction waste can replace coarse aggregates such as gravel, and industrial waste slag can effectively reduce the use of cement.

[0004] There are also studies on controllable low-strength backfill materials in the industry, but only shield mud is used in its preparation, which leads to the problems of high water seepage rate and insufficient strength of the prepared controllable low-strength materials, and cannot meet the construction requirements. Construction waste materials themselves have good water absorption. In the process of preparing controllable low-strength backfill materials, adding an appropriate amount of construction waste materials can not only significantly reduce the water seepage rate of the material, but also effectively improve the strength of the material, and also play a positive role in solving the problem of long solidification time of the material. However, the existing technology has not studied how to adjust the mix ratio of shield slag and construction waste materials with other components to obtain a controllable low-strength backfill material with excellent mechanical properties. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a controllable low-strength backfill material and a preparation method thereof which utilizes construction waste in coordination with shield slag modification.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a controllable low-strength backfill material using construction waste materials in coordination with shield slag modification, wherein the raw materials include construction waste materials, shield slag materials, industrial waste slag, cement, water and modified water glass solution; wherein the mass fractions of the components have the following relationship:

[0008] x parts of construction waste;

[0009] Shield slag (1~2.38)×χ parts;

[0010] 0.3×{(1~2.38)×χ+χ} parts of industrial waste residue;

[0011] Cement 0.03×{(1~2.38)×χ+χ} parts;

[0012] 0.35×{1.33×(1~2.38)×χ+χ} parts of water;

[0013] The modified water glass solution contains 0.0125×{(1~2.38)×χ+χ} parts of solid water glass.

[0014] Technical principle: The present invention uses shield slag as the main raw material, and uses construction waste to replace a certain amount of shield slag to optimize the working performance of controllable low-strength materials. After determining the ratio of shield slag and construction waste, the amount of industrial waste slag, cement, water and solid water glass is determined. By controlling the addition amount of industrial waste slag and solid water glass, the synergistic effect between the materials is achieved, and the synergistic improvement of the mechanical properties of the controllable low-strength backfill material and the synergistic optimization of the working performance are achieved.

[0015] Furthermore, the industrial waste residue is composed of mineral powder and fly ash; the mass ratio of the mineral powder to fly ash is 9:(5-12).

[0016] Furthermore, the modulus of the modified water glass solution is 0.8 to 1.4.

[0017] The present invention also provides a method for preparing a controllable low-strength backfill material using construction waste and shield slag modification as described in the above technical solution, comprising the following steps:

[0018] (1) Preset the mass ratio of each raw material used to prepare the controllable low-strength backfill material; respectively measure the average specific surface area of ​​the construction waste and the shield slag, obtain the specific surface area coefficient according to the average specific surface area of ​​the construction waste and the shield slag, determine the catalytic influence coefficient according to the specific surface area coefficient, and adjust the mass ratio of the construction waste and the shield slag according to the catalytic influence coefficient to determine the basic aggregate basic ratio; the basic aggregate is the construction waste and the shield slag;

[0019] (2) preparing a controllable low-strength backfill material according to the basic aggregate base ratio in step (1) and the preset mass ratio of other raw materials other than the basic aggregate; testing the fluidity change rate of the prepared controllable low-strength backfill material, determining the fluidity influence coefficient according to the fluidity change rate, and performing secondary adjustment on the mass ratio of the construction waste and the shield slag according to the fluidity influence coefficient to determine the final ratio of the basic aggregate;

[0020] (3) Determine the amount of industrial waste slag, cement and water based on the amount of construction waste, the mass ratio of industrial waste slag to basic aggregate, the mass ratio of cement to industrial waste slag and the water-solid ratio; wherein the amount of industrial waste slag is the total amount of mineral powder and fly ash;

[0021] Determine the chemical composition of the shield slag, mineral powder and fly ash used, calculate the silica ratio and calcium oxide ratio of the controllable low-strength backfill material according to the preset mass ratio of the mineral powder and the fly ash, and determine the ratio of the mineral powder and the fly ash according to the obtained silica ratio and calcium oxide ratio;

[0022] Determine the amount of solid water glass, use NaOH to adjust the modulus of the solid water glass, and obtain a modified water glass solution;

[0023] (4) Weigh each raw material according to the amount of raw materials determined in step (3), first mix the construction waste, shield slag, industrial waste slag and cement and pre-mix them, then add water for basic mixing, stir for 10-15 minutes, add the modified water glass solution, continue stirring for 5-10 minutes, and after curing, obtain the controllable low-strength backfill material modified by using construction waste and shield slag.

[0024] Furthermore, in step (1), before determining the average specific surface area of ​​the construction waste, the method further includes the steps of removing impurities, crushing, grinding and screening the construction waste. The present invention removes organic light materials such as plastics from the construction waste by removing impurities, and crushes, grinds and screens the construction waste so that the specific surface area and particle morphology show a high degree of consistency under the action of mechanical force, and the particle size distribution has good grading characteristics, thereby preparing usable fine aggregate, and being able to more effectively regulate the mechanical properties and working performance such as the setting time, fluidity, and compressive strength of the controllable low-strength backfill material.

[0025] Furthermore, the crushing equipment is one of a jaw crusher, a cone crusher, and a hammer crusher; the grinding equipment is one of a Raymond mill, a ball mill, and a cone ball mill; and the particle size of the construction waste after screening is ≤4.5mm.

[0026] Furthermore, in step (1), before determining the average specific surface area of ​​the shield slag, the shield slag is also subjected to water exudation drying and screening.

[0027] Furthermore, the moisture content of the shield slag after the seepage and drying treatment is less than 10%, and the particle size of the shield slag after screening is ≤9.5mm.

[0028] Furthermore, in step (1), the specific surface area refers to the total area per unit mass of the material, which affects the catalytic efficiency of the base activator. The specific surface area can be measured by a specific surface area meter, and each raw material needs to be measured at least three times and the average value is taken.

[0029] Furthermore, in step (1), the specific surface area coefficient is calculated as follows: s =0.05×S cw / S sr ; Among them, R s Represents the specific surface area coefficient, S cw represents the average specific surface area of ​​construction waste, S sr Represents the average specific surface area of ​​shield slag.

[0030] Furthermore, it is known from a large number of empirical studies that S sr <S cw .

[0031] Furthermore, in step (1), the catalytic influence coefficient is determined according to the specific surface area coefficient as follows: if the specific surface area coefficient R s ≤Preset mass ratio Right now The catalytic influence coefficient α = 1; if the specific surface area coefficient R s >Preset mass ratio Right now Then the catalytic influence coefficient is 1.05≤α≤1.15.

[0032] Furthermore, the preset mass ratio The calculation formula is: Among them, QC cw Indicates the preset quality of construction waste, QC sr Indicates the preset mass of shield muck.

[0033] Furthermore, the preset mass ratio The value of

[0034] Furthermore, in step (1), the basic aggregate base ratio is The calculation formula is: Among them, α represents the catalytic influence coefficient, Indicates the preset mass ratio.

[0035] Furthermore, in step (2), the fluidity change rate of the prepared controllable low-strength backfill material is specifically tested as follows:

[0036] Prepare a controllable low-strength backfill material according to the preset mass ratio of each raw material determined in step (1) to obtain slurry 1;

[0037] Prepare a controllable low-strength backfill material according to the basic aggregate base ratio obtained in step (1) and the preset mass ratio of other raw materials to obtain slurry 2;

[0038] The fluidity of slurry one and slurry two at time 0 and time t is measured respectively, and the fluidity change rate is obtained according to the fluidity of slurry one and slurry two.

[0039] Furthermore, the fluidity testing step includes:

[0040] Prepare the test equipment, a clean plastic cylinder and a plastic plate with slightly moistened surface, and place the plastic cylinder in the center of the plastic plate;

[0041] Pour the prepared slurry into the plastic cylinder, tap the container gently to eliminate the gaps between the slurries, and use a scraper to scrape the overflowed slurry to ensure that the slurry fills the entire plastic cylinder;

[0042] Slowly lift the plastic cylinder to spread the slurry evenly on the plastic plate. Use a steel ruler to measure the diameter of the spread circle. Measure twice in the vertical direction each time and take the average of the two measurement results as the fluidity f.

[0043] Furthermore, the calculation formula of the fluidity change rate V is: Among them, f0 represents the fluidity of the slurry at time 0, f t Indicates the fluidity of the slurry at time t, where t is usually 10 to 20 minutes.

[0044] Furthermore, in step (2), the flow characteristics influence coefficient determined according to the fluidity change rate is specifically: if the fluidity change rate V2 of slurry two is greater than the fluidity change rate V1 of slurry one, that is, V2>V1, then the flow characteristics influence coefficient β=1; if the fluidity change rate V2 of slurry two is less than the fluidity change rate V1 of slurry one, that is, V2<V1, then the flow characteristics influence coefficient 1.1≤β≤1.2.

[0045] Furthermore, in step (2), the final proportion of the basic aggregate is The calculation formula is: Among them, β represents the flow characteristics influence coefficient, Indicates the basic aggregate ratio.

[0046] Furthermore, in step (3), the chemical composition of the shield slag, ore powder and fly ash used is specifically determined by: determining the total mass fraction of SiO2, Al2O3, Fe2O3 and CaO in the shield slag, ore powder and fly ash used W CaO .

[0047] Furthermore, in step (3), the calculation formula of the silicon dioxide ratio SR is:

[0048] Furthermore, in step (3), the calculation formula of the calcium oxide ratio LR is:

[0049] Furthermore, in step (3), the ratio of mineral powder to fly ash is determined based on the obtained silica ratio and calcium oxide ratio as follows: if the silica ratio SR and the calcium oxide ratio LR satisfy 2.97≤SR≤3.65 and 0.21≤LR≤0.33, there is no need to adjust the mass ratio of mineral powder to fly ash; if the above value range is not satisfied, it is necessary to further adjust the mass ratio of mineral powder to fly ash so that the alkali activator can play an effective role.

[0050] Furthermore, if the calculated SR is too large, the amount of fly ash should be reduced, and if it is too small, the amount of fly ash should be increased; if the calculated LR is too large, the amount of mineral powder should be reduced, and if it is too small, the amount of mineral powder should be increased; if the calculated SR and LR are both too large, the amount of fly ash should be reduced, and if they are both too small, the amount of fly ash should be increased.

[0051] Furthermore, in step (3), the preparation method of the modified water glass solution is specifically: mixing solid water glass and hot water in a mass ratio of 1:2 to fully dissolve the solid water glass, and adding solid NaOH to adjust the modulus after cooling; the solid water glass is a solid white powder with a modulus of 3.4.

[0052] Furthermore, the chemical formula of the solid water glass is Na2O·mSiO2·nH2O, wherein m represents the modulus of the water glass.

[0053] Furthermore, the calculation formula of the modulus m of the modified water glass solution is:

[0054] Furthermore, the solid NaOH is analytically pure, with a purity of ≥96%, and is in the form of white solid particles.

[0055] Furthermore, in step (3), the mass ratio of the industrial waste slag to the basic aggregate is 0.3:1; the mass ratio of the cement to the industrial waste slag is 0.1:1; the water-solid ratio is 0.35; and the mass ratio of the solid water glass to the basic aggregate is 0.0125:1.

[0056] Furthermore, in step (4), the curing temperature is 21-25° C., the relative humidity is greater than 95%, and the curing time is 24-72 hours.

[0057] Compared with the prior art, the present invention has the following advantages and technical effects:

[0058] (1) The present invention utilizes construction waste to prepare fine aggregate, and uses industrial waste residues such as mineral powder and fly ash as alkaline catalysts, which greatly reduces the amount of cement used and realizes the recycling of waste resources. It is of great significance to promote resource reuse and sustainable development, and has great environmental value and economic benefits.

[0059] (2) The present invention determines the basic aggregate ratio based on the specific surface area of ​​shield slag, the specific surface area of ​​construction waste and the fluidity change rate, and determines the mass ratio of mineral powder and fly ash by measuring the chemical composition of shield slag and industrial waste to calculate the silica ratio and calcium oxide ratio. According to the differences in the materials of each component during each preparation and the different requirements of the site during each construction, the mix ratio is systematically adjusted to meet the required mechanical properties and working performance, thereby ensuring that the controllable low-strength backfill material fully exerts the performance advantages of each material and meets the on-site construction requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0061] Figure 1 This is a process flow chart of a method for preparing a controllable low-strength backfill material using construction waste in conjunction with shield slag modification in Examples 1-3 of the present invention;

[0062] Figure 2 is a process flow chart of step (2) of Example 1-3 of the present invention;

[0063] Figure 3 is a process flow chart of step (3) of Example 1-3 of the present invention;

[0064] Figure 4 This is a process flow chart for determining the ratio of mineral powder and fly ash in step (4) of Example 1-3 of the present invention. DETAILED DESCRIPTION

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0067] The room temperature in the embodiments of the present invention refers to "23±2°C".

[0068] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0069] Example 1

[0070] A method for preparing a controllable low-strength backfill material using construction waste and shield slag modification, the specific steps are:

[0071] (1) removing impurities from existing construction waste, removing organic light materials such as plastics, crushing them with a jaw crusher, grinding them with a Raymond mill, and then sieving them to obtain construction waste with a particle size of ≤4.5 mm; drying the existing shield slag until the moisture content is less than 10%, and then sieving them to obtain shield slag with a particle size of ≤9.5 mm;

[0072] (2) The raw materials used to prepare the controllable low-strength backfill material are mixed in a preset mass ratio: x parts of construction waste, x parts of shield slag, 0.6 x parts of industrial waste slag, 0.06 x parts of cement, 0.8155 x parts of water, and 0.025 x parts of solid water glass in the modified water glass solution. The mass ratio of mineral powder to fly ash in the industrial waste slag is 9:8.06, and the modulus of the modified water glass solution is 1.2; the average specific surface area S of the construction waste in step (1) is determined. cw 374m 2 / kg, the average specific surface area S of the shield slag in step (1) is measured sr 19.4m 2 / kg, according to the calculation formula of specific surface area coefficient, R s =0.05×S cw / S sr =0.964;

[0073] According to the preset quality QC of construction waste cw And the preset quality QC of shield muck sr The ratio of the preset mass ratio is obtained Specific surface area coefficient R s <Preset mass ratio Determine the catalytic influence coefficient α = 1;

[0074] According to the catalytic influence coefficient α, the mass ratio of construction waste and shield slag is adjusted once to determine the basic aggregate ratio according to Calculated

[0075] (3) preparing a controllable low-strength backfill material according to the preset mass ratio of each raw material determined in step (2) to obtain slurry 1; measuring the fluidity f0 of slurry 1 at 0 min to be 137 mm, and the fluidity f0 at 10 min to be 137 mm. t is 173mm, according to The fluidity change rate of slurry 1 is calculated to be V1=3.6mm / min; a controllable low-strength backfill material is prepared according to the basic aggregate base ratio obtained in step (2) and the preset mass ratio of other raw materials to obtain slurry 2; the fluidity f0 of slurry 2 at 0min is measured to be 150mm, and the fluidity f at 10min is 150mm. t is 200mm, according to The fluidity change rate of slurry 2 is calculated to be V2 = 5 mm / min, V2> V1, and the flow characteristic influence coefficient β is determined to be 1;

[0076] According to the flow characteristics influence coefficient β, the mass ratio of construction waste and shield slag is secondary adjusted to determine the final ratio of basic aggregate according to Calculated

[0077] (4) Determine the amount of industrial waste slag, cement and water based on the amount of construction waste, the mass ratio of industrial waste slag to basic aggregate, the mass ratio of cement to industrial waste slag and the water-solid ratio; wherein the amount of industrial waste slag is the total amount of mineral powder and fly ash, the amount of construction waste is x parts, the mass ratio of industrial waste slag to basic aggregate is 0.3:1, the mass ratio of cement to industrial waste slag is 0.1:1, and the water-solid ratio is 0.35;

[0078] The total mass fractions of SiO2, Al2O3, Fe2O3 and CaO in the shield slag, mineral powder and fly ash used were measured as follows: 0.87x parts, 0.256x parts, 0.0355 x parts, W CaO is 0.275 x parts; according to The calculated silica ratio SR is 2.98, according to The calculated calcium oxide ratio LR is 0.244, and the silicon dioxide ratio SR and the calcium oxide ratio LR satisfy 2.97≤SR≤3.65 and 0.21≤LR≤0.33, so there is no need to adjust the mass mix ratio of mineral powder and fly ash;

[0079] The amount of solid water glass is determined, and the modulus of the solid water glass is adjusted using NaOH to obtain a modified water glass solution; wherein the mass ratio of the solid water glass to the basic aggregate is 0.0125:1; the preparation method of the modified water glass solution is: mixing the solid water glass and hot water in a mass ratio of 1:2 to fully dissolve the solid water glass, and after cooling, adding solid NaOH to adjust the modulus to obtain the modified water glass solution; the solid water glass is a solid white powder with a modulus of 3.4;

[0080] The mass proportions of the raw materials in the final controllable low-strength backfill material are shown in Table 1.

[0081] Table 1 Composition of controllable low-strength backfill material in Example 1

[0082]

[0083] (5) Weigh each raw material (Table 1) according to the raw material dosage determined in step (4), first put the construction waste, shield slag, industrial waste slag and cement into a large container and pre-mix to ensure that all dry ingredients are fully mixed; then slowly add the weighed water to start basic mixing, after stirring for 10 minutes, add the modified water glass solution, continue stirring for 10 minutes, ensure that all ingredients are thoroughly mixed, and obtain slurry; inject the obtained slurry into a 70.7mm×70.7mm×70.7mm triple mold for curing at a curing temperature of 23°C and a relative humidity of 97% for 48 hours to obtain a controllable low-strength backfill material modified by construction waste and shield slag.

[0084] The fluidity, bleeding rate, setting time and compressive strength of the controllable low-strength backfill material prepared in Example 1 were measured, and the results are shown in Table 2. The fluidity test was carried out with reference to the test method in the ASTM D-6103 (Test Method for Flow Consistency of Controlled Low Strength Material) specification, the bleeding rate was tested with reference to the Standard for Test Methods for Performance of Ordinary Concrete Mixtures (GB / T50080-2016), and the setting time and compressive strength were tested with reference to the Standard for Test Methods for Basic Performance of Building Mortar (JGJ / T70-2009).

[0085] Table 2 Working performance test results of Example 1

[0086]

[0087] Example 2

[0088] A method for preparing a controllable low-strength backfill material using construction waste and shield slag modification, the specific steps are:

[0089] (1) removing impurities from existing construction waste, removing organic light materials such as plastics, crushing them with a jaw crusher, grinding them with a Raymond mill, and then sieving them to obtain construction waste with a particle size of ≤4.5 mm; drying the existing shield slag until the moisture content is less than 10%, and then sieving them to obtain shield slag with a particle size of ≤9.5 mm;

[0090] (2) Preset the mass ratio of each raw material used to prepare the controllable low-strength backfill material; x parts of construction waste, 1.4x parts of shield slag, 0.72x parts of industrial waste slag, 0.072x parts of cement, 1.0017x parts of water, 0.03x parts of solid water glass in the modified water glass solution, the mass ratio of mineral powder and fly ash in the industrial waste slag is 9:8.06, and the modulus of the modified water glass solution is 1.2; the average specific surface area S of the construction waste in step (1) is determined cw 498m 2 / kg, the average specific surface area S of the shield slag in step (1) is measured sr 14.3m 2 / kg, and R is obtained according to the calculation formula of the specific surface area coefficient s =0.05×S cw / S sr =1.74;

[0091] According to the preset quality QC of construction waste cw And the preset quality QC of shield muck sr The ratio of the preset mass ratio is obtained Comparison of specific surface area coefficient R s >Preset mass ratio The catalytic influence coefficient α was determined to be 1.13;

[0092] According to the catalytic influence coefficient α, the mass ratio of construction waste and shield slag is adjusted once to determine the basic aggregate ratio according to Calculated

[0093] (3) preparing a controllable low-strength backfill material according to the preset mass ratio of each raw material determined in step (2) to obtain slurry 1; measuring the fluidity f0 of slurry 1 at 0 min to be 114 mm, and the fluidity f0 at 15 min to be 114 mm. tis 189mm, according to The fluidity change rate of slurry 1 is calculated to be V1=5mm / min; a controllable low-strength backfill material is prepared according to the basic aggregate base ratio obtained in step (2) and the preset mass ratio of other raw materials to obtain slurry 2; the fluidity f0 of slurry 2 at 0min is measured to be 159mm, and the fluidity f at 15min is 16.8mm. t is 220mm, according to The calculated fluidity change rate of slurry 2 is V2 = 4.07 mm / min, V2 < V1, and the flow characteristic influence coefficient β is determined to be 1.12;

[0094] According to the flow characteristics influence coefficient β, the mass ratio of construction waste and shield slag is secondary adjusted to determine the final ratio of basic aggregate according to Calculated

[0095] (4) Determine the amount of industrial waste slag, cement and water based on the amount of construction waste, the mass ratio of industrial waste slag to basic aggregate, the mass ratio of cement to industrial waste slag and the water-solid ratio; wherein the amount of industrial waste slag is the total amount of mineral powder and fly ash, the mass ratio of industrial waste slag to basic aggregate is 0.3:1, the mass ratio of cement to industrial waste slag is 0.1:1, and the water-solid ratio is 0.35;

[0096] The total mass fractions of SiO2, Al2O3, Fe2O3 and CaO in the shield slag, mineral powder and fly ash used were measured as follows: 1.48x parts, 0.376x parts, 0.0543 x parts, W CaO is 0.448 x parts; according to The calculated silica ratio SR is 3.44, according to The calculated calcium oxide ratio LR is 0.24, and the silicon dioxide ratio SR and the calcium oxide ratio LR satisfy 2.97≤SR≤3.65 and 0.21≤LR≤0.33, so there is no need to adjust the mass mix ratio of mineral powder and fly ash;

[0097] The amount of solid water glass is determined, and the modulus of the solid water glass is adjusted using NaOH to obtain a modified water glass solution; wherein the mass ratio of the solid water glass to the basic aggregate is 0.0125:1; wherein the preparation method of the modified water glass solution is: mixing the solid water glass and hot water in a mass ratio of 1:2 to fully dissolve the solid water glass, and after cooling, adding solid NaOH to adjust the modulus to obtain the modified water glass solution; the solid water glass is a solid white powder with a modulus of 3.4;

[0098] The mass proportions of the raw materials in the final controllable low-strength backfill material are shown in Table 3.

[0099] Table 3 Composition of controllable low-strength backfill material in Example 2

[0100]

[0101] (5) Weigh each raw material (Table 3) according to the raw material dosage determined in step (4), first put the construction waste, shield slag, industrial waste slag and cement into a large container and pre-mix to ensure that all dry ingredients are fully mixed; then slowly add the weighed water to start basic mixing, after stirring for 10 minutes, add the modified water glass solution, continue stirring for 10 minutes, ensure that all ingredients are thoroughly mixed, and obtain slurry; inject the obtained slurry into a 70.7mm×70.7mm×70.7mm triple mold for curing at a curing temperature of 23°C and a relative humidity of 97% for 48 hours to obtain a controllable low-strength backfill material modified by construction waste and shield slag.

[0102] The fluidity, water seepage rate, setting time and compressive strength of the controllable low-strength backfill material prepared in Example 2 were measured. The results are shown in Table 4.

[0103] Table 4 Working performance test results of Example 2

[0104]

[0105] Example 3

[0106] A method for preparing a controllable low-strength backfill material using construction waste and shield slag modification, the specific steps are:

[0107] (1) removing impurities from existing construction waste, removing organic light materials such as plastics, crushing them with a jaw crusher, grinding them with a Raymond mill, and then sieving them to obtain construction waste with a particle size of ≤4.5 mm; drying the existing shield slag until the moisture content is less than 10%, and then sieving them to obtain shield slag with a particle size of ≤9.5 mm;

[0108] (2) The raw materials used to prepare the controllable low-strength backfill material are mixed in a preset mass ratio: x parts of construction waste, x parts of shield slag, 0.6x parts of industrial waste slag, 0.06x parts of cement, 0.8155x parts of water, and 0.025x parts of solid water glass in the modified water glass solution. The mass ratio of mineral powder to fly ash in the industrial waste slag is 9:6.44, and the modulus of the modified water glass solution is 1.2; the average specific surface area S of the construction waste in step (1) is determined. cw 439m 2 / kg, the average specific surface area S of the shield slag in step (1) is measured sr 23.2m 2 / kg, according to the calculation formula of specific surface area coefficient, R s =0.05×S cw / S sr =0.946;

[0109] According to the preset quality QC of construction waste cw And the preset quality QC of shield muck sr The preset mass ratio is obtained by Specific surface area coefficient < preset mass ratio Determine the catalytic influence coefficient α = 1;

[0110] According to the catalytic influence coefficient α, the mass ratio of construction waste and shield slag is adjusted once to determine the basic aggregate ratio according to Calculated

[0111] (3) preparing a controllable low-strength backfill material according to the preset mass ratio of each raw material determined in step (2) to obtain slurry 1; measuring the fluidity f0 of slurry 1 at 0 min to be 117 mm, and the fluidity f0 at 10 min to be 117 mm. t is 174mm, according to The fluidity change rate of slurry 1 is calculated to be V1=5.7mm / min; a controllable low-strength backfill material is prepared according to the basic aggregate base ratio obtained in step (2) and the preset mass ratio of other raw materials to obtain slurry 2; the fluidity f0 of slurry 2 at 0min is measured to be 128mm, and the fluidity f at 10min is 128mm. t is 190mm, according to The calculated fluidity change rate of slurry 2 is V2 = 6.2 mm / min, V2> V1, and the flow characteristic influence coefficient β is determined to be 1;

[0112] According to the flow characteristics influence coefficient β, the mass ratio of construction waste and shield slag is secondary adjusted to determine the final ratio of basic aggregate according to Calculated

[0113] (4) Determine the amount of industrial waste slag, cement and water based on the amount of construction waste, the mass ratio of industrial waste slag to basic aggregate, the mass ratio of cement to industrial waste slag and the water-solid ratio; wherein the amount of industrial waste slag is the total amount of mineral powder and fly ash, the mass ratio of industrial waste slag to basic aggregate is 0.3:1, the mass ratio of cement to industrial waste slag is 0.1:1, and the water-solid ratio is 0.35;

[0114] The total mass fractions of SiO2, Al2O3, Fe2O3 and CaO in the shield slag, mineral powder and fly ash used were measured as follows: is 1.228 x parts, 0.331x parts, 0.0484 x parts, W CaO is 0.353 x parts; according to The calculated silica ratio SR is 3.24, according to The calculated calcium oxide ratio LR is 0.226, and the silicon dioxide ratio SR and the calcium oxide ratio LR satisfy 2.97≤SR≤3.65 and 0.21≤LR≤0.33, so there is no need to adjust the mass mix ratio of mineral powder and fly ash;

[0115] The amount of solid water glass is determined, and the modulus of the solid water glass is adjusted using NaOH to obtain a modified water glass solution; wherein the mass ratio of the solid water glass to the basic aggregate is 0.0125:1; wherein the preparation method of the modified water glass solution is: mixing the solid water glass and hot water in a mass ratio of 1:2 to fully dissolve the solid water glass, and after cooling, adding solid NaOH to adjust the modulus to obtain the modified water glass solution; the solid water glass is a solid white powder with a modulus of 3.4;

[0116] The mass proportions of the raw materials in the final controllable low-strength backfill material are shown in Table 5.

[0117] Table 5 Composition of controllable low-strength backfill material in Example 3

[0118]

[0119] (5) Weigh each raw material (Table 5) according to the raw material dosage determined in step (4), first put the construction waste, shield slag, industrial waste slag and cement into a large container and pre-mix them to ensure that all dry ingredients are fully mixed; then slowly add the weighed water to start basic mixing, after stirring for 10 minutes, add the modified water glass solution, continue stirring for 10 minutes, ensure that all ingredients are thoroughly mixed, and obtain slurry; inject the obtained slurry into a 70.7mm×70.7mm×70.7mm triple mold for curing at a curing temperature of 23°C and a relative humidity of 97% for 72 hours to obtain a controllable low-strength backfill material modified by construction waste and shield slag.

[0120] The fluidity, water seepage rate, setting time and compressive strength of the controllable low-strength backfill material prepared in Example 3 were measured. The results are shown in Table 6.

[0121] Table 6 Working performance test results of Example 3

[0122]

[0123] The fluidity test demonstrates the fluidity of the material; the water seepage rate evaluates the stability of the material; and the setting time provides an important basis for comprehensive consideration of construction scheduling at the test site.

[0124] The following rules can be observed in Examples 1-3: When the proportion of construction waste increases, the fluidity and water bleeding rate of the material show a downward trend, the initial and final setting times are significantly shortened, and the compressive strength increases. The decrease in the water glass modulus will cause the fluidity, water bleeding rate, setting time and compressive strength of the material to decrease. As the amount of mineral powder increases, the fluidity and water bleeding rate of the material decrease, the setting time is shortened, and the compressive strength increases. As the amount of fly ash decreases, the fluidity and water bleeding rate of the material increase, the setting time is prolonged, and the compressive strength decreases.

[0125] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A controllable low-strength backfill material using construction waste and shield slag modification, characterized in that: The raw materials include construction waste, shield slag, industrial waste, cement, water and modified water glass solution; the mass fractions of each component have the following relationship: x parts of construction waste; Shield slag (1~2.38)×χ parts; 0.3×{(1~2.38)×χ+χ} parts of industrial waste residue; Cement 0.03×{(1~2.38)×χ+χ} parts; 0.35×{1.33×(1~2.38)×χ+χ} parts of water; The modified water glass solution contains 0.0125×{(1~2.38)×χ+χ} parts of solid water glass.

2. The controllable low-strength backfill material using construction waste and shield slag modification according to claim 1 is characterized in that: The industrial waste residue is composed of mineral powder and fly ash; the mass ratio of the mineral powder to the fly ash is 9:(5-12).

3. The controllable low-strength backfill material modified by utilizing construction waste and shield slag according to claim 1 is characterized in that: The modulus of the modified water glass solution is 0.8 to 1.

4.

4. A method for preparing a controllable low-strength backfill material using construction waste and shield slag modification as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Presetting the mass ratio of each raw material used to prepare the controllable low-strength backfill material; The average specific surface areas of construction waste and shield slag are measured respectively, and the specific surface area coefficient is obtained according to the ratio of the average specific surface areas of construction waste and shield slag, and the catalytic influence coefficient is determined according to the specific surface area coefficient. The mass ratio of construction waste and shield slag is adjusted once according to the catalytic influence coefficient to determine the basic aggregate basic ratio; the basic aggregate is construction waste and shield slag; (2) preparing a controllable low-strength backfill material according to the basic aggregate base ratio in step (1) and the preset mass ratio of other raw materials other than the basic aggregate; testing the fluidity change rate of the prepared controllable low-strength backfill material, determining the fluidity influence coefficient according to the fluidity change rate, and performing secondary adjustment on the mass ratio of the construction waste and the shield slag according to the fluidity influence coefficient to determine the final ratio of the basic aggregate; (3) Determine the amount of industrial waste slag, cement and water based on the amount of construction waste, the mass ratio of industrial waste slag to basic aggregate, the mass ratio of cement to industrial waste slag and the water-solid ratio; wherein the amount of industrial waste slag is the total amount of mineral powder and fly ash; Determine the chemical composition of the shield slag, mineral powder and fly ash used, calculate the silica ratio and calcium oxide ratio of the controllable low-strength backfill material according to the preset mass ratio of the mineral powder and the fly ash, and determine the ratio of the mineral powder and the fly ash according to the obtained silica ratio and calcium oxide ratio; Determine the amount of solid water glass, use NaOH to adjust the modulus of the solid water glass, and obtain a modified water glass solution; (4) Weigh each raw material according to the amount of raw materials determined in step (3), first mix the construction waste, shield slag, industrial waste slag and cement and pre-mix them, then add water for basic mixing, stir for 10-15 minutes, add the modified water glass solution, continue stirring for 5-10 minutes, and after curing, obtain the controllable low-strength backfill material modified by using construction waste and shield slag.

5. The preparation method according to claim 4, characterized in that: In step (1), before determining the average specific surface area of ​​the construction waste, the method further includes the steps of removing impurities, crushing, grinding and screening the construction waste.

6. The preparation method according to claim 5, characterized in that: The crushing equipment is one of a jaw crusher, a cone crusher, and a hammer crusher; the grinding equipment is one of a Raymond mill, a ball mill, and a cone ball mill; the particle size of the construction waste after screening is ≤4.5mm.

7. The preparation method according to claim 4, characterized in that: In step (1), before determining the average specific surface area of ​​the shield slag, the shield slag is also subjected to water exudation drying treatment and screening.

8. The preparation method according to claim 7, characterized in that: The moisture content of the shield slag after the seepage and drying treatment is less than 10%, and the particle size of the shield slag after screening is less than or equal to 9.5 mm.

9. The preparation method according to claim 4, characterized in that: In step (3), the mass ratio of the industrial waste residue to the basic aggregate is 0.3:1; the mass ratio of the cement to the industrial waste residue is 0.1:1; the water-solid ratio is 0.35; and the mass ratio of the solid water glass to the basic aggregate is 0.0125:

1.

10. The preparation method according to claim 4, characterized in that: In step (4), the curing temperature is 21-25° C., the relative humidity is greater than 95%, and the curing time is 24-72 hours.

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