A method for determining the proportion of copper-doped tailing cement concrete

Abstract

The present application belongs to the technical field of concrete, especially to a method for determining the mixing proportion of copper tailing cement concrete. In the process of determining the mixing proportion of different particle size stones, the present application firstly determines a proportion by using a grading curve, and then verifies the packing void ratio of the stones by using a stone throwing model. The grading curve uses mass ratio, while the stone throwing model calculates the number of stones to be thrown according to volume ratio. In the process of calculating the mixing proportion of stones, the present application considers the influence factors of mass and volume, and provides a method for calculating the number of stones in the process of stone throwing, so as to ensure the accuracy of the calculation result.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, and in particular relates to a method for determining the mix proportion of cement concrete with copper tailings. Background Technology

[0002] The resource utilization of bulk solid waste in road engineering is a green and low-carbon technology. Copper tailings are solid waste generated during copper mining. In the copper ore beneficiation process, more than 98% of the ore becomes copper tailings. The accumulation of copper tailings occupies land and pollutes the environment, making the technology for its resource utilization urgent.

[0003] Copper tailings have fine, uniform particle size and stable physical and chemical properties. Cement concrete is the most widely used building material in civil engineering, mainly composed of cement, gravel, sand, and admixtures. To ensure the compactness of concrete, its production requires a large amount of fine sand and fine powder. Copper tailings, with its stable properties, can be used as a high-quality filler to replace some raw materials in cement concrete.

[0004] Currently, copper tailings are being incorporated into C30-C50 standard strength concrete to a limited extent. In mix design, typically only about 5% copper tailings are added to replace some of the fine sand as filler. However, this application method has significant limitations: the amount of copper tailings is too low, and the proportion is largely determined by engineering experience without considering the material properties of copper tailings or their impact on key properties such as concrete strength and density. This severely restricts the resource utilization efficiency of copper tailings and the full realization of the material's inherent properties.

[0005] Therefore, there is an urgent need for a method to determine the mix proportion of copper-infused cement concrete to solve the above problems. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a method for determining the mix proportion of copper-added tailings cement concrete. This invention controls the proportion of different aggregate sizes by managing the porosity of the aggregate pile, ensuring that the aggregates of different sizes achieve good density and skeletal structure, thereby ensuring the strength of the copper-added tailings cement concrete.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for determining the mix proportion of cement concrete containing copper tailings, the specific steps of which are as follows: S1. Copper tailings cement concrete includes three grades of aggregate, copper tailings, cement and water; first, the aggregate is screened to determine the gradation of each size of aggregate. S2. Based on the continuous gradation requirements of aggregate specified in the "Standard for Quality and Testing Methods of Sand and Stone for Ordinary Concrete" JGJ52, design a three-grade aggregate gradation and determine the mixing ratio of the three grades of aggregate. S3. Randomly select 10 to 20 stones from each grade as stone samples, use 3D scanning to scan each stone sample, establish a real 3D scanning model library for each grade of stone sample, and calculate the average mass and average specific surface area of ​​each grade of stone sample. S4. Calculate the number of stones to be placed in the container according to the mixing ratio of each grade of stone. Use EDEM software to simulate the stone placement process, import the 3D scanning model of the stones, and randomly put stones of each size into the container according to the number of stones to be placed, and obtain the stone packing porosity. S5. Compare the aggregate porosity calculated by the model with the set aggregate porosity of the copper tailings cement concrete. If the aggregate porosity calculated by the model is less than the set aggregate porosity, use the three aggregate mixing ratios as the final aggregate ratio of the copper tailings cement concrete. Otherwise, repeat steps S2-S4 until the calculated aggregate porosity is less than the set aggregate porosity. S6. Cement mortar is applied to the surface of the stones. The remaining volume is the volume of mortar composed of cement, water, and copper tailings. Based on the specific surface area of ​​the stones and the calculated porosity of the stone packing, the amount of cement mortar and mortar used to coat the stones is calculated. Then, based on the water-cement ratio of the cement mortar, the water-cement ratio of the mortar, and the mortar-cement ratio, the amount of cement, water, and copper tailings is obtained.

[0008] Preferably, in step S3, the average mass and specific surface area of ​​each grade of gravel sample are calculated according to the following formula: ; ; In the formula: m—average mass of the stone sample, g; m i —The mass of the i-th stone sample, in g; k—Number of stone samples; SA — Average specific surface area of ​​the stone sample, m² 2 / kg; S i G —The specific surface area (cm²) of the i-th stone sample extracted from the 3D model. 2 ; ρ i G —Dry density of the i-th stone sample, g / cm³ 3 ; V i G —Volume of the i-th stone sample, in cm³ 3 .

[0009] Preferably, in step S4, the number of stones placed in the container is calculated according to the following formula: ; In the formula: n j —The number of stones placed in the j-th row; m r —The total mass of the stones placed in the container, in grams; α j —The percentage of grade j stones by total stone mass, % m j —The average mass of the j-th grade stones, in g.

[0010] Preferably, the three grades of gravel are gravel with a particle size of 5-10mm, gravel with a particle size of 10-20mm, and gravel with a particle size of 20-30mm.

[0011] Preferably, the porosity of the aggregate in the copper tailings-mixed cement concrete is 40%.

[0012] Preferably, the total mass of the stones in the container is 3 to 5 kg.

[0013] Preferably, cement mortar is applied to the surface of the stones, and the remaining volume is mortar composed of cement, water, and copper tailings. Based on the specific surface area and porosity of the stones, the amount of cement mortar and mortar used to coat the stones is calculated using the following formula: ; ; ; In the formula: β j —The volume percentage of the j-th grade stones in the total stones, % α j —The percentage of grade j stones by total stone mass, % ρ j —Density of the j-th grade stones, g / cm³ 3 ; VJ—1m 3 Volume of cement paste encapsulating aggregate in concrete, m 3 ; VC—Porosity of aggregated stones, % μ—thickness of cement mortar film, mm; ρ s —Density of cement mortar, g / cm³ 3 ; SA j — Specific surface area of ​​the j-th stone, m 2 / kg; VS-1m 3 The volume of mortar in concrete, m 3 .

[0014] Preferably, the water-cement ratio of the cement mortar is 0.40 to 0.50, the thickness of the cement mortar film is 0.045 to 0.055 mm, and the water-cement ratio of the mortar composed of cement, water, and copper tailings is 0.28 to 0.36, and the sand-cement ratio is 1.0 to 1.2.

[0015] Preferably, the cement grade is 42.5 or higher.

[0016] Preferably, the copper tailings have a particle size ≤ 2.36 mm, and the proportion of copper tailings with a particle size less than 0.75 mm is 25% to 35%.

[0017] The advantages of this invention are: (1) In view of the shortcomings of the copper tailings cement concrete mix design process, the proportion of various raw materials is completely dependent on experience. The present invention proposes a pile model of different particle size stones. By controlling the proportion of different particle size stones through the pile gaps, the different particle size stones achieve better density and skeleton structure, thereby ensuring the strength of copper tailings cement concrete.

[0018] (2) The present invention adopts the principle of volume filling. The stones form the basic skeleton structure, the cement mortar is attached to the surface of the stones, and the mortar made of copper tailings, water and cement fills the gaps in the stones to form a dense structure. By controlling the mixing ratio of stones, mortar and cement mortar by volume parameters, a scientific calculation method is provided for the amount of copper tailings, which improves the utilization rate of copper tailings and can also ensure the density and strength of cement concrete with copper tailings.

[0019] (3) In determining the blending ratio of stones of different particle sizes, the present invention first uses the gradation curve to initially determine a ratio, and then verifies its packing void ratio through the stone placement model of different particle sizes. The gradation curve uses the mass ratio, while the stone placement model calculates the number of stones placed based on the volume ratio. When calculating the blending ratio of stones, the present invention considers the influence factors of mass and volume, and provides a method for calculating the number of stones during the stone placement process to ensure the accuracy of the calculation results.

[0020] (4) The method for determining the mix proportion of copper tailings cement concrete provided by the present invention uses copper tailings as raw material, controls the copper tailings blending ratio through volume parameters, improves the utilization rate of copper tailings, provides an effective solution for solid waste accumulation and road construction material shortage, and realizes the recycling of solid waste.

[0021] (5) Based on the characteristics of copper tailings and the principle of concrete volume composition, this invention takes into account the performance and density of cement concrete and carries out mix design, thereby designing high-performance and controllable copper tailings cement concrete. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Example 1 S1. Copper tailings-mixed cement concrete includes aggregates with a particle size of 5-10mm, 10-20mm, and 20-30mm, copper tailings, and cement. The aggregates were sieved to determine the gradation composition of each particle size, and the results are shown in Table 1 below. Table 1 Screening Results

[0024] S2. According to the continuous gradation requirements of aggregate specified in the "Standard for Quality and Testing Methods of Sand and Stone for Ordinary Concrete" JGJ52, a three-grade aggregate gradation design is carried out, and the mixing ratio of the three grades of aggregate is determined to be 25% for 20-30mm aggregate, 40% for 10-20mm aggregate, and 35% for 5-10mm aggregate.

[0025] S3. Randomly select 12 stone samples each of 5-10mm, 10-20mm, and 20-30mm diameter stones. Scan each stone sample using 3D scanning to establish a 3D scanning model library for each grade of stone sample. Calculate the average mass and average specific surface area of ​​each grade of stone sample according to the following formula. The results are shown in Table 2 below: ; .

[0026] Table 2

[0027] S4. Based on the mixing ratio of 5-10mm, 10-20mm, and 20-30mm pebbles, calculate the number of pebbles placed in the container. Simulate the pebble placement process using EDEM software, import the 3D scanning model of the pebbles, and randomly add pebbles of each size to the container according to the number of pebbles to be added. The resulting pebble porosity is 41.4%. The number of pebbles in the container is calculated using the following formula, and the results are shown in Table 3 below: ; The total mass of the stones in the container is 3500g.

[0028] Table 3

[0029] S5. Compare the aggregate porosity of 41.4% calculated by the model with the set aggregate porosity of 40% for cement concrete mixed with copper tailings. The aggregate porosity calculated by the model is greater than the set aggregate porosity, so the gradation design should be carried out again.

[0030] S6. According to the continuous gradation requirements of aggregate specified in the "Standard for Quality and Testing Methods of Sand and Stone for Ordinary Concrete" JGJ52, the gradation design is re-constructed, and the three-grade aggregate mixing ratio is determined to be 30% for 20-30mm aggregate, 48% for 10-20mm aggregate, and 22% for 5-10mm aggregate.

[0031] S7. Randomly select 12 stone samples each of 5-10mm, 10-20mm, and 20-30mm diameter stones. Scan each stone sample using 3D scanning to establish a 3D scanning model library for each grade of stone sample. Calculate the average mass and average specific surface area of ​​each grade of stone sample according to the following formula. The results are shown in Table 4 below: ; .

[0032] Table 4

[0033] S8. Based on the mixing ratio of 5-10mm, 10-20mm, and 20-30mm pebbles, calculate the number of pebbles placed in the container. Simulate the pebble placement process using EDEM software, import the 3D scanning model of the pebbles, and randomly add pebbles of each size to the container according to the number of pebbles to be added. The pebble porosity is 38.3%. The number of pebbles in the container is calculated according to the following formula, and the results are shown in Table 5 below: ; The total mass of the stones added is 3500g.

[0034] Table 5

[0035] S9. Compare the aggregate porosity of 38.3% calculated by the model with the set aggregate porosity of 40% for cement concrete with copper tailings. The aggregate porosity calculated by the model is less than the set aggregate porosity. The three aggregate blending ratios are taken as the final aggregate ratio for cement concrete with copper tailings.

[0036] S10. Cement mortar adheres to the surface of the stones. The remaining volume is the volume of mortar composed of cement, water, and copper tailings. Based on the specific surface area of ​​the stones and the porosity of the stones calculated from the model, the amount of cement mortar and mortar used to coat the stones is calculated according to the following formula: ; ; .

[0037] The density of each grade of gravel and the volume ratio of each grade of gravel to the total gravel volume in the above formula are shown in Table 6 below: Table 6

[0038] S11, The thickness of the cement mortar film is 0.05mm, and the density of the cement mortar is 2.0g / cm³. 3 Calculations show that 1m 3 The amount of crushed stone used in copper-admixed tailings cement concrete is 0.617 m³. 3 The volume of cement grout is 0.05m³. 3 The mortar volume is 0.333m³. 3 The mortar density is 2.25 g / cm³. 3 .

[0039] S12 cement grade 42.5, cement mortar water-cement ratio of 0.45, cement, water, and copper tailings mortar water-cement ratio of 0.30, sand-cement ratio of 0.9, the final amount of cement concrete per cubic meter is shown in Table 7 below: Table 7

[0040] Cement concrete was prepared according to the above proportions, and the strength of the concrete was tested. The results are shown in Table 8 below: Table 8

[0041] As shown in Table 8, the concrete prepared by the mix proportion determined by the method of the present invention meets the C40 strength requirement.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the mix proportion of copper-blended cement concrete, characterized in that, The specific steps are as follows: S1. Copper tailings cement concrete includes three grades of aggregate, copper tailings, cement, and water; first, the aggregate is screened to determine its gradation composition. S2. Based on the continuous gradation requirements of gravel, design a three-grade gravel gradation and determine the blending ratio of the three grades of gravel. S3. Randomly select 10 to 20 stones from each grade as stone samples, use 3D scanning to scan each stone sample, establish a 3D scanning model library for each grade of stone samples, and calculate the average mass and average specific surface area of ​​each grade of stone samples. S4. Calculate the number of stones to be placed in the container according to the mixing ratio of each grade of stone. Use EDEM software to simulate the stone placement process, import the 3D scanning model of the stones, and randomly put stones of each size into the container according to the number of stones to be placed, and obtain the stone packing porosity. S5. Compare the aggregate porosity calculated by the model with the set aggregate porosity of the copper tailings cement concrete. If the aggregate porosity calculated by the model is less than the set aggregate porosity, use the three aggregate mixing ratios as the final aggregate ratio of the copper tailings cement concrete. Otherwise, repeat steps S2-S4 until the calculated aggregate porosity is less than the set aggregate porosity. S6. Based on the specific surface area of ​​the gravel and the calculated porosity of the gravel, calculate the amount of cement mortar and mortar used to coat the gravel. Then, based on the water-cement ratio of the cement mortar, the water-cement ratio of the mortar, and the sand-cement ratio, obtain the amounts of cement, water, and copper tailings.

2. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that, In step S3, the average mass and specific surface area of ​​each grade of gravel sample are calculated according to the following formula: In the formula: m—average mass of the stone sample, g; m i —The mass of the i-th stone sample, in g; k—Number of stone samples; SA — Average specific surface area of ​​the stone sample, m² 2 / kg; S i G —The specific surface area (cm²) of the i-th stone sample extracted from the 3D model. 2 ; ρ i G —Dry density of the i-th stone sample, g / cm³ 3 ; V i G —Volume of the i-th stone sample, in cm³ 3 .

3. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that, In step S4, the number of stones placed in the container is calculated according to the following formula: In the formula: n j —The number of stones placed in the j-th row; m r —The total mass of the stones placed in the container, in grams; α j —The mass percentage of the j-th grade stones in the total stones, % m j —The average mass of the j-th grade stones, in g.

4. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that: The three grades of gravel are gravel with a particle size of 5-10mm, gravel with a particle size of 10-20mm, and gravel with a particle size of 20-30mm.

5. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that: The copper-added tailings cement concrete has a stone porosity of 40%.

6. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 3, characterized in that: The total mass of the stones in the container should be 3-5 kg.

7. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that, Based on the specific surface area and porosity of the aggregate, the amount of cement mortar and mortar used to coat the aggregate is calculated using the following formula: In the formula: β j —The volume percentage of the j-th grade stones in the total stones, % α j —The percentage of grade j stones by total stone mass, % ρ j —Density of the j-th grade stones, g / cm³ 3 ; VJ—1m 3 Volume of cement paste encapsulating aggregate in concrete, m 3 ; VC—Porosity of aggregated stones, % μ—thickness of cement mortar film, mm; ρ s —Density of cement mortar, g / cm³ 3 ; SA j — Specific surface area of ​​the j-th stone, m 2 / kg; VS-1m 3 The volume of mortar in concrete, m 3 .

8. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 7, characterized in that: The water-cement ratio of the cement mortar is 0.40 to 0.50, the thickness of the cement mortar film is 0.045 to 0.055 mm, and the water-cement ratio of the mortar composed of cement, water, and copper tailings is 0.28 to 0.36, and the sand-cement ratio is 1.0 to 1.

2.

9. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that: The cement grade is 42.5 or higher.

10. The method for determining the mix proportion of copper-blended tailings cement concrete according to claim 1, characterized in that: The copper tailings have a particle size ≤ 2.36 mm, and the proportion of copper tailings with a particle size less than 0.75 mm is 25% to 35%.

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