Pump concrete based on solid waste and preparation method thereof

Abstract

The invention relates to the technical field of pump concrete, in particular to pump concrete based on solid waste and a preparation method of the pump concrete. The pump concrete is prepared from the following components in parts by mass: 250 to 350 parts of cement, 100 to 200 parts of composite solid waste admixture, 700 to 850 parts of recycled fine aggregate, 1000 to 1200 parts of recycled coarse aggregate, 4 to 8 parts of water reducing agent and 140 to 170 parts of water, the composite solid waste admixture comprises construction waste micro powder, tailing micro powder and slag micro powder in a mass ratio of (40-60): (20-40): (20-30). According to the invention, the ternary ratio of the composite solid waste admixture and the precise regulation and control of each component achieve the balance of solid waste utilization and concrete performance. Large-mixing-amount application of solid waste such as construction waste, tailings and slag is achieved, and workability and mechanical properties needed by pump concrete are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of pumped concrete technology, and in particular to a pumped concrete based on solid waste and its preparation method. Background Technology

[0002] Pumped concrete, a key material widely used in construction, needs to possess good fluidity, cohesiveness, and water retention to meet pumping requirements under various working conditions. However, traditional pumped concrete production heavily relies on cement clinker and natural sand and gravel aggregates, resulting in high costs and resource consumption and environmental pressures. Meanwhile, the large-scale stockpiling of solid wastes such as copper tailings, steel slag, fly ash, construction waste, and gold mine tailings not only occupies significant land resources but also risks environmental pollution, making their resource utilization an urgent issue to be addressed.

[0003] To address this, researchers have attempted to apply these solid wastes to the preparation of pumped concrete, aiming to reduce costs and alleviate environmental pressure through solid waste utilization. However, existing technologies still have limitations: some solutions involve a single type of solid waste with limited dosage; and some solutions result in concrete with poor workability, failing to meet the requirements of high-performance pumped concrete. Summary of the Invention

[0004] The purpose of this invention is to address the problem in existing technologies where solid waste utilization and concrete workability cannot be simultaneously achieved. It provides a method for preparing pumpable concrete based on solid waste, and through precise control of the ternary ratio and components of the composite solid waste admixture, a balance between solid waste utilization and concrete performance is achieved. This method enables the large-scale application of solid waste such as construction waste, tailings, and slag, while ensuring the required workability and mechanical properties of pumpable concrete, providing a solution with both environmental value and technical feasibility for the green transformation of the construction industry.

[0005] To achieve the above objectives, the present invention provides a pumpable concrete based on solid waste, comprising the following components in parts by weight:

[0006] 250-350 parts cement, 100-200 parts composite solid waste admixture, 700-850 parts recycled fine aggregate, 1000-1200 parts recycled coarse aggregate, 4-8 parts water-reducing agent, and 140-170 parts water.

[0007] The composite solid waste admixture includes construction waste powder, tailings powder and slag powder, and the mass ratio of construction waste powder, tailings powder and slag powder is (40-60):(20-40):(20-30).

[0008] Preferably, the specific surface area of ​​the construction waste powder is greater than or equal to 400 m². 2 / kg, the mass fraction of particles with a diameter of less than or equal to 0.075mm in the construction waste powder is greater than or equal to 20%;

[0009] The specific surface area of ​​the tailings powder is 450 m². 2 / kg-600m 2 / kg;

[0010] The specific surface area of ​​slag powder is 500 m². 2 / kg-800m 2 / kg, the mass fraction of CaO in the slag powder is greater than or equal to 35%.

[0011] Preferably, the fineness modulus of the recycled fine aggregate is 2.6-3.2; and the particle size of the recycled coarse aggregate is 5mm-20mm.

[0012] Preferably, the water-reducing agent includes a polycarboxylate water-reducing agent, and the water reduction rate of the water-reducing agent is greater than or equal to 25%.

[0013] Preferably, the pumped concrete also includes fibers, and the mass fraction of fibers in the pumped concrete is 0.5 to 1.5 parts.

[0014] Preferably, the fiber comprises polyethylene fiber or polypropylene fiber, and the fiber length is 10mm-20mm.

[0015] The present invention also provides a method for preparing pumpable concrete based on solid waste, comprising the following steps:

[0016] The components are mixed, allowed to stand, and then poured to obtain pumped concrete based on solid waste.

[0017] Preferably, mixing the components includes:

[0018] (1) Mix construction waste powder, tailings powder and slag powder to obtain composite solid waste admixture;

[0019] (2) The composite solid waste admixture and cement are mixed to obtain a cementitious material;

[0020] (3) Mix the cementitious material and the remaining components.

[0021] Preferably, in the mixing process of step (1), a surface modifier is also added; the ratio of the total mass of construction waste powder, tailings powder and slag powder to the mass of the surface modifier is 100: (0.05-0.1).

[0022] Preferably, the surface modifier includes triethanolamine and polyvinyl alcohol, with a mass ratio of triethanolamine to polyvinyl alcohol of (0.5-1.5):(0.5-1.5).

[0023] The beneficial effects of this invention are as follows:

[0024] This invention provides a pumpable concrete based on solid waste, comprising the following components in parts by weight: 250-350 parts cement, 100-200 parts composite solid waste admixture, 700-850 parts recycled fine aggregate, 1000-1200 parts recycled coarse aggregate, 4-8 parts water-reducing agent, and 140-170 parts water; the composite solid waste admixture includes construction waste powder, tailings powder, and slag powder, with the mass ratio of construction waste powder, tailings powder, and slag powder being (40-60):(20-40):(20-30).

[0025] This invention uses 100-200 parts of composite solid waste admixture to replace cement, combined with the use of recycled aggregate, significantly increasing the amount of solid waste disposed of and reducing the environmental risks of solid waste stockpiling. The composite solid waste admixture is composed of construction waste powder, tailings powder, and slag powder in a specific ratio. The CaO and SiO2 contained in the construction waste powder can react with Ca(OH)2 generated during cement hydration, supplementing CSH gel, enhancing the interfacial transition zone between aggregate and slurry, improving slurry cohesion, and preventing aggregate segregation. The Fe2O3 / Al2O3 in the tailings powder refines the pore structure through physical filling, reducing bleeding channels, lowering the bleeding rate, and maintaining slump stability. The slag powder utilizes the pozzolanic activity of CaO to stimulate secondary hydration reactions, generating more gel-like products and improving overall strength. The synergistic effect of these three components reduces cement usage and compensates for the performance deficiencies of individual solid wastes, thereby improving the workability and strength of pumpable concrete.

[0026] In summary, this invention achieves a balance between solid waste utilization and concrete performance through the precise control of the ternary ratio and components of the composite solid waste admixture. It enables the large-scale application of solid wastes such as construction waste, tailings, and slag, while ensuring the workability and mechanical properties required for pumped concrete, providing a solution with both environmental value and technical feasibility for the green transformation of the construction industry. Detailed Implementation

[0027] This invention provides a pumpable concrete based on solid waste, comprising the following components in parts by weight:

[0028] 250-350 parts cement, 100-200 parts composite solid waste admixture, 700-850 parts recycled fine aggregate, 1000-1200 parts recycled coarse aggregate, 4-8 parts water-reducing agent, and 140-170 parts water.

[0029] The composite solid waste admixture includes construction waste powder, tailings powder and slag powder, and the mass ratio of construction waste powder, tailings powder and slag powder is (40-60):(20-40):(20-30).

[0030] In some embodiments of the present invention, the construction waste powder is made by crushing and grinding waste concrete and / or wall materials; the specific surface area of ​​the construction waste powder is greater than or equal to 400 m². 2 / kg, the mass fraction of particles with a diameter of less than or equal to 0.075mm in the construction waste powder is greater than or equal to 20%.

[0031] In some embodiments of the present invention, the tailings powder is made by grinding iron tailings and / or copper tailings; the specific surface area of ​​the tailings powder is 450 m². 2 / kg-600m 2 / kg.

[0032] In some embodiments of the present invention, the slag powder is made by grinding blast furnace slag; the specific surface area of ​​the slag powder is 500 m². 2 / kg-800m 2 / kg, the mass fraction of CaO in the slag powder is greater than or equal to 35%.

[0033] In some embodiments of the present invention, the recycled fine aggregate is obtained by crushing and screening construction waste; the fineness modulus of the recycled fine aggregate is 2.6-3.2.

[0034] In some embodiments of the present invention, the recycled coarse aggregate is obtained by crushing and screening construction waste; the particle size of the recycled coarse aggregate is 5mm-20mm.

[0035] In some embodiments of the present invention, the water-reducing agent includes a polycarboxylate water-reducing agent, and the water reduction rate of the water-reducing agent is greater than or equal to 25%.

[0036] In some embodiments of the present invention, the pumped concrete further includes fibers, and the mass fraction of the fibers in the pumped concrete is 0.5 to 1.5 parts.

[0037] In some embodiments of the present invention, the fibers include polyethylene fibers or polypropylene fibers, and the length of the fibers is 10mm-20mm.

[0038] The fiber has excellent crack-resistant properties, which can reduce plastic cracks and improve volume stability.

[0039] The present invention also provides a method for preparing pumpable concrete based on solid waste, comprising the following steps:

[0040] The components are mixed, allowed to stand, and then poured to obtain pumped concrete based on solid waste.

[0041] In some embodiments of the present invention, the specific steps for mixing the components include:

[0042] (1) Mix construction waste powder, tailings powder and slag powder to obtain composite solid waste admixture;

[0043] (2) The composite solid waste admixture and cement are mixed to obtain a cementitious material;

[0044] (3) Mix the cementitious material and the remaining components.

[0045] In this invention, during the mixing process in step (1), a surface modifier is also added; the ratio of the total mass of construction waste powder, tailings powder and slag powder to the mass of the surface modifier is 100: (0.05-0.1).

[0046] Surface modifiers can inhibit particle agglomeration and reduce shrinkage.

[0047] In this invention, the surface modifier includes triethanolamine and polyvinyl alcohol, with a mass ratio of triethanolamine to polyvinyl alcohol of (0.5-1.5):(0.5-1.5).

[0048] In this invention, the settling temperature is 20℃-30℃, and the settling time is 10min-15min.

[0049] The present invention will be further described below with reference to embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0050] Example 1

[0051] This embodiment provides a pumpable concrete based on solid waste, comprising the following components in parts by weight:

[0052] 300 parts cement, 150 parts composite solid waste admixture (composite solid waste admixture includes construction waste powder, tailings powder and slag powder, with a mass ratio of construction waste powder, tailings powder and slag powder of 50:30:25), 775 parts recycled fine aggregate, 1100 parts recycled coarse aggregate, 6 parts water-reducing agent, 1 part fiber, and 155 parts water.

[0053] Construction waste powder is made by grinding crushed waste concrete and wall materials, with a specific surface area of ​​500 m². 2 / kg, the mass fraction of particles with a diameter of less than or equal to 0.075mm in the construction waste powder is 38%; the tailings powder is made from iron tailings and has a specific surface area of ​​525m². 2 / kg; Slag powder is made from blast furnace slag by grinding, with a specific surface area of ​​650m². 2 / kg, the mass fraction of CaO in the slag powder is 45%.

[0054] Recycled fine aggregate and recycled coarse aggregate are obtained by crushing and screening construction waste. The fineness modulus of recycled fine aggregate is 2.9, and the particle size of recycled coarse aggregate is 12mm.

[0055] The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 29%; the fiber is polyethylene fiber with a length of 15mm.

[0056] This embodiment also provides a method for preparing pumpable concrete based on solid waste, including the following steps:

[0057] Construction waste powder, tailings powder, and slag powder are mixed to obtain a mixture. Surface modifiers (the mass ratio of the mixture to the surface modifier is 100:0.07, and the surface modifiers include triethanolamine and polyvinyl alcohol, with a mass ratio of 1:1) are added to the mixture to obtain a composite solid waste admixture.

[0058] The composite solid waste admixture is mixed with cement to obtain a cementitious material.

[0059] The cementitious material and remaining components are mixed, allowed to stand at 25°C for 12 minutes, and then poured to obtain solid waste-based pumped concrete.

[0060] Example 2

[0061] This embodiment provides a pumpable concrete based on solid waste, comprising the following components in parts by weight:

[0062] 275 parts cement, 175 parts composite solid waste admixture (the composite solid waste admixture includes construction waste powder, tailings powder and slag powder, with a mass ratio of 55:25:28), 750 parts recycled fine aggregate, 1050 parts recycled coarse aggregate, 5 parts water-reducing agent, 0.85 parts fiber, and 150 parts water.

[0063] Construction waste powder is made by grinding crushed waste concrete and wall materials, with a specific surface area of ​​475 m². 2 / kg, the mass fraction of particles with a diameter of 0.075mm or less in the construction waste powder is 33%; the tailings powder is made from copper tailings and has a specific surface area of ​​500m². 2 / kg; Slag powder is made from blast furnace slag by grinding, with a specific surface area of ​​600m². 2 / kg, the mass fraction of CaO in the slag powder is 40%.

[0064] Recycled fine aggregate and recycled coarse aggregate are obtained by crushing and screening construction waste. The fineness modulus of recycled fine aggregate is 2.7, and the particle size of recycled coarse aggregate is 10mm.

[0065] The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 29%; the fiber is a polypropylene fiber with a length of 12mm.

[0066] This embodiment also provides a method for preparing pumped concrete based on solid waste, which is the same as in Embodiment 1.

[0067] Example 3

[0068] This embodiment provides a pumpable concrete based on solid waste, comprising the following components in parts by weight:

[0069] 325 parts cement, 125 parts composite solid waste admixture (the composite solid waste admixture includes construction waste powder, tailings powder and slag powder, with a mass ratio of construction waste powder, tailings powder and slag powder of 45:35:22), 800 parts recycled fine aggregate, 1150 parts recycled coarse aggregate, 7 parts water-reducing agent, 1.25 parts fiber, and 160 parts water.

[0070] Construction waste powder is made by grinding crushed waste concrete and wall materials, with a specific surface area of ​​520 m². 2 / kg, the mass fraction of particles with a diameter of 0.075mm or less in the construction waste powder is 40%; the tailings powder is made from iron tailings and has a specific surface area of ​​550m². 2 / kg; Slag powder is made from blast furnace slag by grinding, with a specific surface area of ​​700m². 2 / kg, the mass fraction of CaO in the slag powder is 42%.

[0071] Recycled fine aggregate and recycled coarse aggregate are obtained by crushing and screening construction waste. The fineness modulus of recycled fine aggregate is 3.0, and the particle size of recycled coarse aggregate is 8mm.

[0072] The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of 29%; the fiber is polyethylene fiber with a length of 16mm.

[0073] This embodiment also provides a method for preparing pumped concrete based on solid waste, which is the same as in Embodiment 1.

[0074] Example 4

[0075] This embodiment provides a pumped concrete based on solid waste, which differs from Embodiment 1 in that the mass fraction of each component is as follows:

[0076] 250 parts cement, 200 parts composite solid waste admixture (composite solid waste admixture includes construction waste powder, tailings powder and slag powder, with a mass ratio of construction waste powder, tailings powder and slag powder of 40:20:30), 700 parts recycled fine aggregate, 1000 parts recycled coarse aggregate, 4 parts water-reducing agent, 0.5 parts fiber, and 140 parts water.

[0077] This embodiment also provides a method for preparing pumped concrete based on solid waste, which is the same as in Embodiment 1.

[0078] Example 5

[0079] This embodiment provides a pumped concrete based on solid waste, which differs from Embodiment 1 in that the mass fraction of each component is as follows:

[0080] 350 parts cement, 100 parts composite solid waste admixture (composite solid waste admixture includes construction waste powder, tailings powder and slag powder, with a mass ratio of construction waste powder, tailings powder and slag powder of 40:20:30), 850 parts recycled fine aggregate, 1200 parts recycled coarse aggregate, 8 parts water-reducing agent, 1.5 parts fiber, and 170 parts water.

[0081] This embodiment also provides a method for preparing pumped concrete based on solid waste, which is the same as in Embodiment 1.

[0082] Comparative Example 1

[0083] This comparative example provides a pumped concrete, which differs from Example 1 in that the addition of composite solid waste admixture is omitted, and the composite solid waste admixture is replaced with an equal mass of cement.

[0084] This comparative example also provides a method for preparing pumped concrete, including the following steps:

[0085] Mix the components, let stand at 25°C for 12 minutes, and then pour to obtain pumped concrete.

[0086] Comparative Example 2

[0087] This comparative example provides a pumped concrete, which differs from Example 1 in that the composite solid waste admixture is replaced with a single construction waste powder, with the construction waste powder having a mass fraction of 150 parts.

[0088] This comparative example also provides a method for preparing pumped concrete, including the following steps:

[0089] A surface modifier (the mass ratio of construction waste powder to surface modifier is 100:0.07, and the surface modifier includes triethanolamine and polyvinyl alcohol, with a mass ratio of 1:1) is added to construction waste powder to obtain solid waste admixture.

[0090] Solid waste admixtures are mixed with cement to obtain cementitious materials.

[0091] Mix the cementitious material and the remaining components, let it stand at 25°C for 12 minutes, and then pour it to obtain pumped concrete.

[0092] Comparative Example 3

[0093] This comparative example provides a pumped concrete that is basically the same as Example 1, except that the composite solid waste admixture is replaced with a single slag powder, and the mass fraction of the slag powder is 150 parts.

[0094] This comparative example also provides a method for preparing pumped concrete, including the following steps:

[0095] A surface modifier (the mass ratio of slag powder to surface modifier is 100:0.07, and the surface modifier includes triethanolamine and polyvinyl alcohol, with a mass ratio of 1:1) is added to slag powder to obtain solid waste admixture.

[0096] Solid waste admixtures are mixed with cement to obtain cementitious materials.

[0097] Mix the cementitious material and the remaining components, let it stand at 25°C for 12 minutes, and then pour it to obtain pumped concrete.

[0098] Comparative Example 4

[0099] This comparative example provides a pumped concrete that is basically the same as Example 1, except that the composite solid waste admixture is replaced with a single tailings powder, and the mass fraction of the tailings powder is 150 parts.

[0100] This comparative example also provides a method for preparing pumped concrete, including the following steps:

[0101] A surface modifier (the mass ratio of tailings powder to surface modifier is 100:0.07, and the surface modifier includes triethanolamine and polyvinyl alcohol, with a mass ratio of 1:1) is added to the tailings powder to obtain a solid waste admixture.

[0102] Solid waste admixtures are mixed with cement to obtain cementitious materials.

[0103] Mix the cementitious material and the remaining components, let it stand at 25°C for 12 minutes, and then pour it to obtain pumped concrete.

[0104] Experimental Example 1

[0105] The pumped concrete based on solid waste prepared in Examples 1-5 and the pumped concrete prepared in Comparative Examples 1-4 were subjected to performance tests. The slump and bleeding rate were tested according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the compressive strength was tested according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and the shrinkage rate was tested according to GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The performance test results of different pumped concretes are shown in Table 1.

[0106] Table 1 Performance test results of different pumped concrete

[0107] Case Slump (mm) Water exudation rate (%) 7-day compressive strength (MPa) 28-day compressive strength (MPa) <![CDATA[28d shrinkage rate (*10 -6 )]]> Example 1 210 5.0 28.5 48.2 320 Example 2 205 5.8 26.8 46.5 335 Example 3 200 6.2 27.3 47.1 330 Example 4 185 7.5 24.0 42.8 350 Example 5 195 6.8 25.2 44.3 340 Comparative Example 1 215 4.5 30.1 52.0 310 Comparative Example 2 180 12.5 22.3 40.5 420 Comparative Example 3 190 8.0 26.2 45.8 510 Comparative Example 4 175 9.5 19.8 36.2 380

[0108] Therefore, this invention employs the aforementioned solid waste-based pumped concrete and its preparation method. Through the precise control of the ternary ratio and components of the composite solid waste admixture, a balance between solid waste utilization and concrete performance is achieved. This not only enables the large-scale application of solid wastes such as construction waste, tailings, and slag, but also ensures the workability and mechanical properties required for pumped concrete, providing a solution with both environmental value and technical feasibility for the green transformation of the construction industry.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A pumpable concrete based on solid waste, characterized in that, The components include the following parts by mass: 250-350 parts cement, 100-200 parts composite solid waste admixture, 700-850 parts recycled fine aggregate, 1000-1200 parts recycled coarse aggregate, 4-8 parts water-reducing agent, and 140-170 parts water. The composite solid waste admixture includes construction waste powder, tailings powder and slag powder, and the mass ratio of construction waste powder, tailings powder and slag powder is (40-60):(20-40):(20-30).

2. The pumped concrete based on solid waste according to claim 1, characterized in that, The specific surface area of ​​construction waste powder is greater than or equal to 400 m². 2 / kg, the mass fraction of particles with a diameter of less than or equal to 0.075mm in the construction waste powder is greater than or equal to 20%; The specific surface area of ​​the tailings powder is 450 m². 2 / kg-600m 2 / kg; The specific surface area of ​​slag powder is 500 m². 2 / kg-800m 2 / kg, the mass fraction of CaO in the slag powder is greater than or equal to 35%.

3. The solid waste-based pumped concrete according to claim 1 or 2, characterized in that, The fineness modulus of recycled fine aggregate is 2.6-3.2; the particle size of recycled coarse aggregate is 5mm-20mm.

4. The solid waste-based pumped concrete according to claim 1 or 2, characterized in that, Water-reducing agents include polycarboxylate water-reducing agents, and the water reduction rate of the water-reducing agents is greater than or equal to 25%.

5. The solid waste-based pumped concrete according to claim 1 or 2, characterized in that, Pumped concrete also includes fibers, with the fiber content in pumped concrete ranging from 0.5 to 1.5 parts by mass.

6. The pumped concrete based on solid waste according to claim 5, characterized in that, The fibers include polyethylene fibers or polypropylene fibers, with a length of 10mm-20mm.

7. The method for preparing pumpable concrete based on solid waste according to any one of claims 1-6, characterized in that, Includes the following steps: The components are mixed, allowed to stand, and then poured to obtain pumped concrete based on solid waste.

8. The method for preparing pumpable concrete based on solid waste according to claim 7, characterized in that, Mixing the components includes: (1) Mix construction waste powder, tailings powder and slag powder to obtain composite solid waste admixture; (2) The composite solid waste admixture and cement are mixed to obtain a cementitious material; (3) Mix the cementitious material and the remaining components.

9. The method for preparing pumpable concrete based on solid waste according to claim 8, characterized in that, In the mixing process of step (1), a surface modifier is also added; the ratio of the total mass of construction waste powder, tailings powder and slag powder to the mass of the surface modifier is 100: (0.05-0.1).

10. The method for preparing pumpable concrete based on solid waste according to claim 9, characterized in that, The surface modifiers include triethanolamine and polyvinyl alcohol, with a mass ratio of triethanolamine to polyvinyl alcohol of (0.5-1.5):(0.5-1.5).