A method for mix proportion design of full-solid waste recycled flowable mixture

Abstract

The application provides a mixing proportion design method of a full-solid-waste regenerated flow state mixture, and belongs to the technical field of flow state mixtures.The application provides a mixing proportion design method of a full-solid-waste regenerated flow state mixture, adopts full-solid-waste cementing materials and full-solid-waste bases as raw materials, and realizes the resource utilization of various solid wastes.In addition, the composition range determination method of the cementing materials is simple, reasonable and universal, the performance of different composition cementing materials is comprehensively reflected by a small amount of mixing proportion, and is suitable for any ternary cementing material system.The strength model of the application has good fitting degree and reliable verification, and is beneficial to the popularization and application of the full-solid-waste regenerated flow state mixture.

Description

Technical Field

[0001] This invention relates to the field of fluidized bed mixing technology, and more particularly to a mix design method for a fully recycled solid waste fluidized bed mixture. Background Technology

[0002] Traditional backfill compaction leads to subsidence, which not only severely affects the appearance and function of road surfaces, causing traffic accidents, but also damages buildings and infrastructure, increasing engineering risks. Furthermore, insufficiently compacted backfill is unstable and prone to geological disasters such as landslides, collapses, and ground subsidence. Flowable mixtures, as a type of controlled low-strength material (CLSM) used in backfilling projects, possess high fluidity and can self-fill under its own weight with little or no vibration, forming a self-compacting structure. This makes them more attractive and practical compared to traditional compacted backfill. In recent years, many scholars both domestically and internationally have conducted research on flowable mixtures, using manufactured sand and soil to replace concrete aggregates to prepare cement-based flowable mixtures, and using lime-activated slag powder and fly ash to prepare non-cement-based flowable mixtures.

[0003] With the rapid development of urbanization and construction activities, the amount of construction waste is constantly increasing. To promote sustainable development and resource protection, many countries and regions have formulated relevant laws and policies to actively encourage the resource utilization of construction waste. The core of construction waste resource utilization is to process bricks, tiles, and concrete into recycled aggregates to replace natural aggregates in the preparation of building materials, making full use of solid waste while reducing the demand for original natural materials. Numerous studies on the application of recycled aggregates in building materials have been conducted both domestically and internationally, including research on the impact of recycled aggregates on the performance of cement-based CLSMs. Redundant soil, as part of the construction waste recycling process, consists of particles smaller than the specified size separated by the soil removal system, accounting for 25% to 40% of the total construction waste. Its composition is complex, containing not only mortar and brick-concrete particles but also a large amount of clay particles, making it unusable as aggregate. Most of it becomes secondary waste, seriously affecting the actual resource utilization rate of construction waste.

[0004] On the other hand, the production and use of cement are placing an increasingly heavy burden on resources and the environment. Reducing or even eliminating dependence on cement has gradually become a major direction in building materials research. Alkaline waste residues in solid waste are irritating and corrosive; open-air dumping and landfilling cause serious impacts on the natural environment and urgently require safe utilization. Because the Cl- in alkaline waste residues can damage the passivation film on the surface of reinforcing steel bars, accelerating corrosion and thus having a depassivating effect, they cannot be used in structural construction. Backfill materials are mostly used for road base courses and road backfilling, where there is no risk of reinforcing steel corrosion.

[0005] In summary, if alkaline waste residue, slag powder, and fly ash can replace traditional cement, and surplus soil can be utilized extensively, supplemented with recycled aggregates to adjust the gradation and prepare fluidized bed mixtures for backfilling, it will have a positive impact on the resource utilization of construction waste and the promotion of sustainable development. However, the composition of alkaline waste residue varies greatly across different regions and industries, making it difficult to apply any single technology to others. Therefore, finding a feasible mix design method is a necessary condition for the widespread application of all-solid-waste recycled fluidized bed mixtures. Summary of the Invention

[0006] The purpose of this invention is to provide a mix design method for a fully recycled fluidized bed of solid waste, which solves the problem that the composition of solid waste varies greatly in different regions and industries, making it impossible to apply the same mix design.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for designing the mix proportion of a fully recycled solid waste fluidized bed mixture, comprising the following steps:

[0009] (1) Using alkaline waste residue, slag powder and fly ash as cementing materials, the triangular isenthalpy diagram method is used to set alkaline waste residue, slag powder and fly ash as the bottom, left waist and right waist respectively. The content of alkaline waste residue and fly ash ranges from 0 to 80% and the content of slag ranges from 100% to 20%. The characteristic distribution of cementing material strength and fluidity in the triangular isenthalpy diagram is plotted respectively. The higher value area of ​​cementing material strength and fluidity in the triangular isenthalpy diagram is selected to determine the content range of alkaline waste residue, slag powder and fly ash, that is, the composition range of cementing material.

[0010] (2) Within the dosage range determined in step (1), select any point on the triangular isenthalpy diagram to determine the composition of the cementitious material. Fix the cementitious material dosage at 10%. Use redundant soil and brick-concrete fine aggregate as the base material. Change the ratio of redundant soil to brick-concrete fine aggregate. Control the amount of water added with a flow spread of 180-200 mm. Mix the cementitious material and redundant soil with brick-concrete fine aggregate to obtain the mixture. Measure the compressive strength and bleeding rate of the mixture. Select the brick-concrete fine aggregate / redundant soil group with a bleeding rate of no more than 8% and the highest compressive strength as the base material composition.

[0011] (3) Within the dosage range determined in step (1), select at least 6 typical points in the triangular isenthalpy diagram, and select 3 total cementitious materials in the range of 8% to 20% based on the cementitious material composition of the typical points. Add the base material according to the proportion determined in step (2), control the amount of water added with a flow spread of 180 to 200 mm, prepare recycled fluidized mixtures with different mix proportions, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions.

[0012] (4) Combine the dosage of each cementitious material with the 28-day compressive strength of the recycled fluid mixture specimen to establish the ternary linear regression equation shown in Equation 1, y=A0+A1x1+A2x2+A3x3 Equation 1;

[0013] In Equation 1: y is the 28-day compressive strength of the recycled fluidized bed specimen, in MPa; x1 is the mass percentage of slag powder in the recycled fluidized bed, %; x2 is the mass percentage of fly ash in the recycled fluidized bed, %; x3 is the mass percentage of alkaline waste residue in the recycled fluidized bed, %; A0 is the intercept of the equation; A1, A2, and A3 represent the linear regression coefficients.

[0014] Regression analysis was performed on the ternary linear regression equation to determine the values ​​of A1, A2, and A3, thus obtaining Equation 1 with x1, x2, and x3 as variables; the correlation coefficient R of Equation 1 is... 2 A good fit is achieved when the value is greater than 0.8; otherwise, add cementitious material dosage points to the triangular isenthalpy diagram, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions according to step (3). Then, fit the results again using all 28-day compressive strength test results until R... 2 Greater than 0.8;

[0015] Six composition points are randomly selected within the dosage range determined in step (1), and three total cementitious materials are selected within the range of 8% to 20%. These are substituted into equation 1 to calculate the predicted strength value. The base material is added in proportion, and the amount of water added is controlled with a flow spread of 180 to 200 mm. The 28-day compressive strength of the recycled fluidized mixture specimen is measured, and the difference range between the measured value and the predicted value is calculated. When the difference range of each recycled fluidized mixture specimen is not greater than 10%, the model is relatively accurate and can be used for strength prediction of recycled fluidized mixture. Otherwise, cementitious material dosage points are added to the triangular isenthalpy diagram, and the 28-day compressive strength is measured according to step (3). All 28-day compressive strength test results are fitted and tested again until the difference range between the measured value and the predicted value is not greater than 10%.

[0016] (6) According to the target strength requirements, calculate the composition of the cementitious material according to the equation determined in step (4), and combine it with the base material composition determined in step (2) to obtain the mix proportion of the whole solid waste recycled fluid mixture.

[0017] Preferably, in step (1), when determining the dosage range of alkaline waste residue, slag powder and fly ash by selecting the region with higher values ​​of cementitious material strength and fluidity in the triangular isenthalpy diagram, the compressive strength of the cementitious material is used as the main reference and the fluidity as the auxiliary reference.

[0018] Preferably, in step (1), the strength of the cementitious material includes 3d compressive strength, 7d compressive strength and 28d compressive strength.

[0019] Preferably, in step (3), the total amount of three cementitious materials is selected from 8% to 20% as follows: one cementitious material has a total amount of less than 10%, another cementitious material has a total amount of 20%, and the remaining cementitious material has a total amount of 8% to 20%.

[0020] Preferably, in step (5), when determining the mix proportion of the whole solid waste recycled fluidized mixture, the production quality level coefficient is 1.2, and the principle is to use low slag powder and high alkaline waste residue.

[0021] Preferably, the alkaline waste residue is the waste residue generated after obtaining acetylene gas by hydrolysis of calcium carbide, and the residue on a 0.075mm sieve is no more than 30%.

[0022] Preferably, the fine aggregate for brick-concrete mixture is obtained by crushing and screening construction waste mainly composed of brick and concrete; the particle size of the fine aggregate for brick-concrete mixture is less than 4.75 mm.

[0023] Preferably, in step (4), the regression analysis of the ternary linear regression equation is performed using Origin software.

[0024] Preferably, the redundant soil is the screened material from the soil removal process in the recycling of construction waste; the particle size of the redundant soil is not greater than 25 mm.

[0025] This invention provides a mix design method for a fully recycled fluidized bed mixture, which uses fully recycled solid waste cementitious materials and fully recycled solid waste base materials as raw materials, thereby realizing the resource utilization of multiple solid wastes.

[0026] Furthermore, the method for determining the composition range of cementitious materials in this invention is simple, reasonable, and universal, comprehensively reflecting the performance of cementitious materials with different compositions using a small amount of mixing ratio, and is applicable to any ternary cementitious material system.

[0027] The strength model of this invention has a good fit and reliable verification, which is conducive to the promotion and application of whole solid waste recycled fluidized mixture. Attached Figure Description

[0028] Figure 1 A triangular isenthalpy diagram;

[0029] Figure 2 This is a characteristic distribution diagram of the strength and fluidity of cementitious materials in a triangular isenthalpy diagram. Detailed Implementation

[0030] This invention provides a method for mix design of a fully recycled solid waste fluidized bed mixture, comprising the following steps:

[0031] (1) Using alkaline waste residue, slag powder and fly ash as cementing materials, the triangular isenthalpy diagram method is used to set alkaline waste residue, slag powder and fly ash as the bottom, left waist and right waist respectively. The content of alkaline waste residue and fly ash ranges from 0 to 80% and the content of slag ranges from 100% to 20%. The characteristic distribution of cementing material strength and fluidity in the triangular isenthalpy diagram is plotted respectively. The higher value area of ​​cementing material strength and fluidity in the triangular isenthalpy diagram is selected to determine the content range of alkaline waste residue, slag powder and fly ash, that is, the composition range of cementing material.

[0032] (2) Within the dosage range determined in step (1), select any point on the triangular isenthalpy diagram to determine the composition of the cementitious material. Fix the cementitious material dosage at 10%. Use redundant soil and brick-concrete fine aggregate as the base material. Change the ratio of redundant soil to brick-concrete fine aggregate. Control the amount of water added with a flow spread of 180-200 mm. Mix the cementitious material and redundant soil with brick-concrete fine aggregate to obtain the mixture. Measure the compressive strength and bleeding rate of the mixture. Select the brick-concrete fine aggregate / redundant soil group with a bleeding rate of no more than 8% and the highest compressive strength as the base material composition.

[0033] (3) Within the dosage range determined in step (1), select at least 6 typical points in the triangular isenthalpy diagram, and select 3 total cementitious materials in the range of 8% to 20% based on the cementitious material composition of the typical points. Add the base material according to the proportion determined in step (2), control the amount of water added with a flow spread of 180 to 200 mm, prepare recycled fluidized mixtures with different mix proportions, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions.

[0034] (4) Combine the dosage of each cementitious material with the 28-day compressive strength of the recycled fluid mixture specimen to establish the ternary linear regression equation shown in Equation 1, y=A0+A1x1+A2x2+A3x3 Equation 1;

[0035] In Equation 1: y is the 28-day compressive strength of the recycled fluidized bed specimen, in MPa; x1 is the mass percentage of slag powder in the recycled fluidized bed, %; x2 is the mass percentage of fly ash in the recycled fluidized bed, %; x3 is the mass percentage of alkaline waste residue in the recycled fluidized bed, %; A0 is the intercept of the equation; A1, A2, and A3 represent the linear regression coefficients.

[0036] Regression analysis was performed on the ternary linear regression equation to determine the values ​​of A1, A2, and A3, thus obtaining Equation 1 with x1, x2, and x3 as variables; the correlation coefficient R of Equation 1 is... 2 A good fit is achieved when the value is greater than 0.8; otherwise, add cementitious material dosage points to the triangular isenthalpy diagram, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions according to step (3). Then, fit the results again using all 28-day compressive strength test results until R...2 Greater than 0.8;

[0037] Six composition points are randomly selected within the dosage range determined in step (1), and three total cementitious materials are selected within the range of 8% to 20%. These are substituted into equation 1 to calculate the predicted strength value. The base material is added in proportion, and the amount of water added is controlled with a flow spread of 180 to 200 mm. The 28-day compressive strength of the recycled fluidized mixture specimen is measured, and the difference range between the measured value and the predicted value is calculated. When the difference range of each recycled fluidized mixture specimen is not greater than 10%, the model is relatively accurate and can be used for strength prediction of recycled fluidized mixture. Otherwise, cementitious material dosage points are added to the triangular isenthalpy diagram, and the 28-day compressive strength is measured according to step (3). All 28-day compressive strength test results are fitted and tested again until the difference range between the measured value and the predicted value is not greater than 10%.

[0038] (5) According to the target strength requirements, calculate the composition of the cementitious material according to the equation determined in step (4), and combine it with the base material composition determined in step (2) to obtain the mix proportion of the whole solid waste recycled fluid mixture.

[0039] This invention first uses alkaline waste residue, slag powder, and fly ash as cementing materials. Using a triangular isenthalpy diagram method, alkaline waste residue (JZ), slag powder (Slag), and fly ash (FA) are respectively designated as the lower bottom, left side, and right side. The content of alkaline waste residue and fly ash ranges from 0% to 80%, and the content of slag ranges from 100% to 20% (e.g., ...). Figure 1 As shown, the characteristic distributions of the strength and fluidity of cementitious materials in the triangular isenthalpy diagram are plotted respectively. The higher value regions of the strength and fluidity of cementitious materials in the triangular isenthalpy diagram are selected to determine the dosage range of alkaline waste residue, slag powder and fly ash, that is, the composition range of cementitious materials.

[0040] In this invention, the alkaline waste residue is preferably the waste residue generated after obtaining acetylene gas by hydrolysis of calcium carbide, and the residue on the 0.075mm sieve of the alkaline waste residue is preferably no more than 30%.

[0041] In this invention, the slag powder is obtained by grinding the water slag produced by blast furnace ironmaking; it conforms to GB / T 18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete".

[0042] In this invention, the fly ash is a powder particle collected from the flue gas after coal combustion; conforming to GB / T 1596-2017 "Fly Ash for Cement and Concrete".

[0043] In this invention, the strength of the cementitious material includes 3d compressive strength, 7d compressive strength and 28d compressive strength.

[0044] In this invention, when determining the dosage range of alkaline waste residue, slag powder and fly ash by selecting the region with higher values ​​of cementitious material strength and fluidity in the triangular isenthalpy diagram, it is preferable to use the compressive strength of cementitious material as the main reference and fluidity as the auxiliary reference; wherein, the compressive strength is more preferably based on the 28-day compressive strength as the main reference and the compressive strength at other ages as the auxiliary reference.

[0045] After determining the dosage range of alkaline waste residue, slag powder and fly ash, i.e. the composition range of cementitious materials, this invention selects any one point in the triangular isenthalpy diagram within the dosage range determined in step (1), fixes the cementitious material dosage at 10%, uses redundant soil and brick-concrete fine aggregate as base material, varies the ratio of redundant soil to brick-concrete fine aggregate, controls the amount of water added with a flow spread of 180-200 mm, mixes the cementitious material and redundant soil with brick-concrete fine aggregate to obtain a mixture; measures the compressive strength and bleeding rate of the mixture, selects the brick-concrete fine aggregate / redundant soil group with a bleeding rate of no more than 8% and the highest compressive strength as the base material composition.

[0046] In this invention, the redundant soil is preferably the undersize material from the soil removal process in the recycling of construction waste; the particle size of the redundant soil is preferably no greater than 25 mm.

[0047] In this invention, the fine aggregate for brick-concrete mixture is preferably obtained by crushing and screening construction waste mainly composed of brick and concrete; the particle size of the fine aggregate for brick-concrete mixture is preferably less than 4.75 mm.

[0048] After determining the composition of the base material, within the dosage range determined in step (1), at least 6 typical points are selected in the triangular isenthalpy diagram. Based on the cementitious material composition of the typical points, 3 total cementitious materials are selected from 8% to 20%, and the base material is added according to the proportion determined in step (2). The amount of water added is controlled with a flow spread of 180 to 200 mm. Different proportions of recycled fluidized mixtures are prepared, and the 28-day compressive strength of the recycled fluidized mixture specimens with different proportions is measured.

[0049] In this invention, the typical point refers to a point that is dispersed within the dosage range. In this invention, the preferred total amount of three cementitious materials selected within the range of 8% to 20% is: one cementitious material with a total amount below 10%, another cementitious material with a total amount of 20%, and the remaining cementitious material with a total amount between 8% and 20%. In embodiments of this invention, the total amounts of the three cementitious materials are 10%, 8%, and 20%, respectively.

[0050] After measuring the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions, this invention combines the dosage of each cementitious material with the 28-day compressive strength of the recycled fluidized mixture specimens to establish a ternary linear regression equation as shown in Equation 1: y = A0 + A1x1 + A2x2 + A3x3 (Equation 1).

[0051] In Equation 1: y is the 28-day compressive strength of the recycled fluidized mixture specimen, in MPa; x1 is the mass percentage of slag powder in the recycled fluidized mixture, %; x2 is the mass percentage of fly ash in the recycled fluidized mixture, %; x3 is the mass percentage of alkaline waste residue in the recycled fluidized mixture, %; A0 is the intercept of the equation; A1, A2, and A3 represent the linear regression coefficients. Before establishing the ternary linear regression equation, this invention needs to convert the proportion of each component in the cementitious material into its proportion in the recycled fluidized mixture.

[0052] Regression analysis was performed on the ternary linear regression equation, preferably using Origin software to determine the values ​​of A1, A2, and A3, thereby obtaining Equation 1 with x1, x2, and x3 as variables; the correlation coefficient R of Equation 1 is... 2 A good fit is achieved when the value is greater than 0.8; otherwise, add cementitious material dosage points to the triangular isenthalpy diagram, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions according to step (3). Then, fit the results again using all 28-day compressive strength test results until R... 2 Greater than 0.8;

[0053] Six composition points are randomly selected within the dosage range determined in step (1), and three total cementitious materials are selected within the range of 8% to 20%. These are substituted into equation 1 to calculate the predicted strength value. The base material is added in proportion, and the amount of water added is controlled with a flow spread of 180 to 200 mm. The 28-day compressive strength of the recycled fluidized mixture specimen is measured, and the difference range between the measured value and the predicted value is calculated. When the difference range of each recycled fluidized mixture specimen is not greater than 10%, the model is relatively accurate and can be used for strength prediction of recycled fluidized mixtures. Otherwise, cementitious material dosage points are added to the triangular isenthalpy diagram, and the 28-day compressive strength is measured according to step (3). The results of all 28-day compressive strength tests are used to fit and verify the test again until the difference range between the measured value and the predicted value is not greater than 10%.

[0054] After determining Equation 1, the present invention calculates the composition of the cementitious material according to the equation determined in step (4) based on the target strength requirements, and combines it with the base material composition determined in step (2) to obtain the mix proportion of the all-solid waste recycled fluidized mixture.

[0055] When determining the mix proportion of the all-solid waste recycled fluidized mixture, the present invention preferably considers a production quality level coefficient of 1.2, and follows the principle of low slag powder content and high alkaline waste residue content.

[0056] This invention designs the mix proportions based on all-solid-waste cementitious materials and all-solid-waste base materials; the method for determining the composition range of cementitious materials is simple, reasonable, and universal, and a small mix proportion can comprehensively reflect the performance of cementitious materials with different compositions; the strength model of this invention has a good fitting degree and reliable verification, which is conducive to the promotion and application of all-solid-waste recycled fluidized mixtures.

[0057] The following detailed description of the mix design method for the all-solid waste recycled fluidized bed mixture provided by the present invention, with reference to specific embodiments, should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] (1) The range of cementitious material composition including alkaline waste residue, slag powder and fly ash was determined by using the triangular isenthalpy diagram method. The cementitious material composition design is shown in Table 1.

[0060] Table 1. Cementitious Material Composition Design

[0061]

[0062] Based on the experimental results, the characteristic distributions of the strength and fluidity of the cementitious material in the triangular isenthalpy diagram are plotted. Figure 2 ;

[0063] Analyzing the contour lines in the diagram, the dosage range of each component is determined to be 15%–50% for alkaline waste residue, 20%–85% for slag, and 0%–40% for fly ash.

[0064] (2) Determine the composition of the base material, including redundant soil and fine aggregate of brick-concrete composite.

[0065] The composition of the adhesive material in group B was selected, with a total dosage of 10%. The test results are shown in Table 2.

[0066] Table 2. Test results for different base material compositions

[0067]

[0068] Analysis of the test results in Table 2 shows that the overall bleeding rate of the mixture is much lower than 8%, and the compressive strength at all ages is higher when the fine aggregate / soil ratio is 0.25.

[0069] (3) Determine the compressive strength of the recycled fluidized mixture.

[0070] The composition of the rubber material at typical points P, Q, R, S, T, and U in the triangular isenthalpy diagram was selected. The total amount of rubber material was selected as 8%, 10%, and 20%, and the compressive strength of the recycled fluid mixture was measured as shown in Table 3.

[0071] Table 3 Compressive strength data of recycled fluidized bed mixture

[0072]

[0073] (4) Fitting and verification of mixture strength

[0074] For the data in Table 3, regression analysis was performed using Origin software to determine A1, A2, and A3, resulting in the following equations.

[0075] y=-1.52076+0.53668x1+0.18455x2+0.22292x3

[0076] Correlation coefficient R 2 =0.97322, indicating a good fit.

[0077] Selecting a triangular isenthalpy diagram ( Figure 1 Points L, K, J, M, N, and O in the formula are used, with 20%, 15%, and 10% of the total adhesive material, respectively. These values ​​are then substituted into the above equation to calculate the predicted strength of the recycled fluidized bed mixture. The mixture is prepared according to the specified proportions, and the compressive strength of the recycled fluidized bed mixture is measured. The predicted and experimental values ​​for each proportion of the mixture are shown in Table 4 below.

[0078] Table 4. Predicted and experimental values ​​of compressive strength of recycled fluidized bed mixtures with different mix proportions.

[0079]

[0080]

[0081] The difference between the experimental and predicted values ​​of the 28-day compressive strength of the mixture specimens ranges from -6.9% to 9%, indicating that the model is relatively accurate and can be used for strength prediction of mixtures.

[0082] (5) Determination of the mix proportion of the mixture

[0083] According to the equation determined in (4), if the 28-day design strengths are 1.0 MPa, 2.0 MPa, and 4.0 MPa respectively, and the production quality level coefficient is 1.2, then the trial mix strengths are 1.2 MPa, 2.4 MPa, and 4.8 MPa respectively. The calculation results of the mix proportion and the actual strength are shown in Table 5 below.

[0084] Table 5. Calculation results of mixture proportions and actual strength

[0085]

[0086] As shown in Table 5, the actual strength of the all-solid waste recycled fluidized mixture designed according to the mix design method of the present invention is higher than the target design strength, indicating that the method of the present invention has high accuracy and can meet the requirements of practical applications.

[0087] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A mix design method for a fully recycled solid waste fluidized bed mixture, comprising the following steps: (1) Using alkaline waste residue, slag powder and fly ash as cementing materials, the triangular isenthalpy diagram method is used to set alkaline waste residue, slag powder and fly ash as the bottom, left waist and right waist respectively. The content of alkaline waste residue and fly ash ranges from 0 to 80% and the content of slag ranges from 100% to 20%. The characteristic distribution of cementing material strength and fluidity in the triangular isenthalpy diagram is plotted respectively. The higher value area of ​​cementing material strength and fluidity in the triangular isenthalpy diagram is selected to determine the content range of alkaline waste residue, slag powder and fly ash, that is, the composition range of cementing material. (2) Within the dosage range determined in step (1), select any point on the triangular isenthalpy diagram to determine the composition of the cementitious material. Fix the cementitious material dosage at 10%. Use redundant soil and brick-concrete fine aggregate as the base material. Change the ratio of redundant soil to brick-concrete fine aggregate. Control the amount of water added with a flow spread of 180-200 mm. Mix the cementitious material and redundant soil with brick-concrete fine aggregate to obtain the mixture. Measure the compressive strength and bleeding rate of the mixture. Select the brick-concrete fine aggregate / redundant soil group with a bleeding rate of no more than 8% and the highest compressive strength as the base material composition. (3) Within the dosage range determined in step (1), select at least 6 typical points in the triangular isenthalpy diagram, and select 3 total cementitious materials in the range of 8% to 20% based on the cementitious material composition of the typical points. Add the base material according to the proportion determined in step (2), control the amount of water added with a flow spread of 180 to 200 mm, prepare recycled fluidized mixtures with different mix proportions, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions. (4) Combine the dosage of each cementitious material with the 28-day compressive strength of the recycled fluid mixture specimen to establish the ternary linear regression equation shown in Equation 1, y=A0+A1x1+A2x2+A3x3 Equation 1; In Equation 1: y is the 28-day compressive strength of the recycled fluidized bed specimen, in MPa; x1 is the mass percentage of slag powder in the recycled fluidized bed, %; x2 is the mass percentage of fly ash in the recycled fluidized bed, %; x3 is the mass percentage of alkaline waste residue in the recycled fluidized bed, %; A0 is the intercept of the equation; A1, A2, and A3 represent the linear regression coefficients. Regression analysis was performed on the ternary linear regression equation to determine the values ​​of A1, A2, and A3, thus obtaining Equation 1 with x1, x2, and x3 as variables; the correlation coefficient R of Equation 1 is... 2 A good fit is achieved when the value is greater than 0.8; otherwise, add cementitious material dosage points to the triangular isenthalpy diagram, and determine the 28-day compressive strength of recycled fluidized mixture specimens with different mix proportions according to step (3). Then, fit the results again using all 28-day compressive strength test results until R... 2 Greater than 0.8; Within the dosage range determined in step (1), six composition points are randomly selected, and three total cementitious materials are selected within the range of 8% to 20%. These are substituted into Equation 1 to calculate the predicted strength value. The base material is added in proportion, and the amount of water added is controlled with a flow spread of 180 to 200 mm. The 28-day compressive strength of the recycled fluidized mixture specimen is measured, and the range of difference between the measured value and the predicted value is calculated. When the range of difference between each recycled fluidized mixture specimen is not greater than 10%, the model is relatively accurate and can be used for strength prediction of recycled fluidized mixtures. Otherwise, continue to add cementitious material dosage points to the triangular isenthalpy diagram, and determine the 28-day compressive strength according to the steps (3) described above. Use all the 28-day compressive strength test results to fit and test again until the difference between the measured value and the predicted value is no more than 10%. (5) According to the target strength requirements, calculate the composition of the cementitious material according to the equation determined in step (4), and combine it with the base material composition determined in step (2) to obtain the mix proportion of the whole solid waste recycled fluid mixture.

2. The mix design method according to claim 1, characterized in that, In step (1), when determining the dosage range of alkaline waste residue, slag powder and fly ash by selecting the region with higher values ​​of cementitious material strength and fluidity in the triangular isenthalpy diagram, the compressive strength of the cementitious material is the main reference and the fluidity is the auxiliary reference.

3. The mix design method according to claim 1 or 2, characterized in that, In step (1), the strength of the cementitious material includes 3d compressive strength, 7d compressive strength and 28d compressive strength.

4. The mix design method according to claim 1, characterized in that, In step (3), three total amounts of cementitious materials are selected from 8% to 20% as follows: one total amount of cementitious material is less than 10%, another total amount of cementitious material is 20%, and the remaining total amount of cementitious material is between 8% and 20%.

5. The mix design method according to claim 1, characterized in that, In step (5), when determining the mix proportion of the whole solid waste recycled fluidized mixture, the production quality level coefficient is 1.2, and the principle is to use low slag powder and high alkaline waste residue.

6. The mix design method according to claim 1 or 2, characterized in that, The alkaline waste residue is the waste residue generated after obtaining acetylene gas by hydrolysis of calcium carbide, and the residue on a 0.075mm sieve is no more than 30%.

7. The mix design method according to claim 1, characterized in that, The fine aggregate for brick-concrete mixture is obtained by crushing and screening construction waste, which is mainly composed of brick and concrete; the particle size of the fine aggregate for brick-concrete mixture is less than 4.75 mm.

8. The mix design method according to claim 1, characterized in that, In step (4), the regression analysis of the ternary linear regression equation is performed using Origin software.

9. The mix design method according to claim 1, characterized in that, The redundant soil is the screened material from the soil removal process during the recycling of construction waste; the particle size of the redundant soil is no greater than 25 mm.

Images