Method for determining proportion of copper-doped tailing dry hard concrete

Abstract

The invention belongs to the technical field of concrete preparation, and particularly relates to a method for determining the proportion of dry and hard concrete doped with copper tailings. The method comprises the following specific steps: S1, determining a water-cement ratio according to the preparation strength of the hard concrete; s2, calculating the specific surface area of the sample; s3, calculating the average adhesive cement film thickness of the cement adhesive cement coated aggregate; and S4, calculating the use amount of the cement and the water. According to the method, the industrial waste copper tailings are subjected to resource utilization, the cement dosage is easy to control in the proportioning design process of the method, the efficiency is high, and the strength and stability of the dry and hard cement concrete doped with the copper tailings are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete preparation, and particularly relates to a method for determining the mix ratio of dry-hardened concrete mixed with copper tailings. Background Art

[0002] According to statistics, hundreds of millions of tons of waste tailings are produced every year, and the recycling rate of tailings is only about 18.9%. The main treatment method for a large amount of unused tailings is stacking, which wastes a large amount of land resources.

[0003] Small components such as arch slope protection, gutter covers, curb stones, and slope protection bricks are auxiliary structures in highway construction. In the traditional in-situ wet operation process, the consumption of wood, cement, and water is huge and the waste is serious. The small component factory adopts a centralized production method, and the production water and formwork can be recycled to reduce resource and energy consumption. The small components produced centrally in the factory generally use dry-hardened concrete with a slump less than 10 mm. In order to ensure the strength and density of dry-hardened cement concrete, the amount of fine aggregate used is generally large. The copper tailings have uniform particles and fine particle size, and can replace the fine aggregate to efficiently realize the resource utilization of copper tailings.

[0004] Currently, when designing the mix ratio of dry-hardened concrete, the initial cement dosage is mainly determined based on experience, and then dry-hardened concrete is prepared by trial-mixing different dosages of cement, and the final cement dosage is determined based on a large number of tests. This method not only lacks a theoretical basis and it is difficult to obtain the optimal cement dosage, but also the test volume is large, resulting in a large waste of manpower and material resources. Therefore, there is an urgent need to propose a method for determining the mix ratio of dry-hardened concrete mixed with copper tailings to solve the above problems. Summary of the Invention

[0005] In order to overcome the above defects in the prior art, the present invention provides a method for determining the mix ratio of dry-hardened concrete mixed with copper tailings. The present invention determines the cement dosage of dry-hardened concrete mixed with copper tailings based on theoretical calculation, scientifically and effectively determines its optimal cement dosage, and can adapt to the changes of raw materials and timely adjust the optimal cement dosage.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for determining the mix ratio of dry-hardened concrete mixed with copper tailings, comprising the following steps: S1. Determine the water-cement ratio according to the designed strength of the dry-hardened concrete; S2. Weigh 500 - 2000 g of copper tailings, 500 - 2000 g of fine aggregate, and 500 - 2000 g of coarse aggregate respectively. After immersing and filtering the three samples, centrifuge them in a closed container for 2 - 3 minutes in sequence, and weigh the mass of each sample after centrifugation; then dry them and weigh the mass of each sample after drying. Calculate the specific surface area of each sample according to the water film thickness and the volume of adsorbed water on the surface of each sample. S3. Prepare cement mortar according to the water - cement ratio determined above. Since the particle size of the coarse aggregate is relatively large and it is convenient to measure, select and weigh ≥20 coarse aggregates. Measure the volume and mass of each coarse aggregate, and calculate the specific surface area of each coarse aggregate according to the method in step S2. Then immerse the coarse aggregates completely in the cement mortar, take them out and place them in a standard concrete curing room for curing. Take out the specimens, measure the volume of each coarse aggregate after being wrapped with cement mortar, and calculate the average mortar film thickness of the cement mortar - wrapped coarse aggregates weighed. S4. According to the average mortar film thickness, the dosages of fine aggregate, coarse aggregate, and copper tailings in 1 cubic meter of dry - hard concrete, and the specific surface areas of each sample, calculate the dosages of cement and water in 1 cubic meter of dry - hard concrete according to the following formula: ; ; ; ; Where: ρ j - The density of cement mortar, g / cm 3 ; α - The water - cement ratio of dry - hard concrete; ρ s - The density of water, g / cm 3 ; ρ n - The density of cement, g / cm 3 ; P j - The mass of cement mortar in 1 cubic meter of dry - hard concrete, kg; u j - The average mortar film thickness of cement mortar - wrapped coarse aggregates, μm; m 粗 - The mass of coarse aggregate in 1 cubic meter of dry - hard concrete, kg; m 细 - The mass of fine aggregate in 1 cubic meter of dry - hard concrete, kg; m w - The mass of copper tailings in 1 cubic meter of dry - hard concrete, kg; SA 粗 - The specific surface area of coarse aggregate m 2 / kg; SA 细 - Specific surface area of fine aggregate, m 2 / kg; SA w - Specific surface area of copper tailings, m 2 / kg; P s - Mass of water in 1 m³ of dry - hard concrete, kg; P n - Mass of cement in 1 m³ of dry - hard concrete, kg.

[0007] Preferably, in step S2, the calculation formula for the specific surface area of each sample is as follows: ; In the formula: SA - Specific surface area of the sample, m 2 / kg; m s - Mass of the sample after immersion, centrifugal rotation and drying, g; m g - Mass of the sample after drying, g; m k - Mass of the sample during sampling, g; μ s - Thickness of the water film, μm; ρ s - Density of water, g / cm 3 .

[0008] Preferably, in step S3, the calculation formula for the average mortar film thickness of the cement mortar coating the coarse aggregate is as follows: ; In the formula: u j - Average mortar film thickness of the cement mortar coating the coarse aggregate, μm; n - Quantity of coarse aggregate; V i - Volume of the i - th sample in the coarse aggregate before immersion in the cement mortar, mm 3 ; VV i - Volume of the i - th sample in the coarse aggregate after curing, mm 3 ; SA i - Specific surface area of the i - th sample in the coarse aggregate, m 2 / kg; m i - Mass of the i - th sample in the coarse aggregate, g.

[0009] Preferably, in step S4, the dry - hard concrete of one party includes 520 - 580 kg of coarse aggregate, 820 - 900 kg of fine aggregate and 380 - 420 kg of copper tailings.

[0010] Preferably, in step S2, the immersion time ≥ 24 h.

[0011] Preferably, in step S2, absorbent paper is placed at the bottom of the container to absorb the water after centrifugation, so as to avoid affecting the subsequent weighing.

[0012] Preferably, in step S3, the immersion time in cement mortar ≥ 10 min; the curing time ≥ 7 days.

[0013] Preferably, the particle size of the coarse aggregate is 5 - 10 mm; the particle size of the fine aggregate is 0 - 5 mm.

[0014] Preferably, the particle size of the copper tailings ≤ 1.18 mm, and the content of copper tailings with a particle size below 0.075 mm ≤ 40%.

[0015] Preferably, the water film thickness is 8 - 15 um.

[0016] The advantages of the present invention are as follows: (1) The present invention utilizes the industrial waste copper tailings for resource utilization. In the process of proportion design of this method, the cement dosage is easy to control, the efficiency is relatively high, and the strength and stability of the dry - hard cement concrete mixed with copper tailings are ensured.

[0017] (2) Aiming at the defects existing in the proportion design process of dry - hard concrete mixed with copper tailings, the present invention determines the specific surface area of the aggregate and copper tailings and the thickness of the cement mortar film formed by cement mortar wrapping through experiments, calculates the optimal cement dosage of dry - hard concrete mixed with copper tailings, maximally exerts the effect of cement, and can adjust the cement dosage in real time through theoretical calculation according to the changes of the aggregate and copper tailings raw materials, effectively exerts the best effect of cement, improves the material performance of dry - hard concrete mixed with copper tailings, improves the proportion design efficiency, greatly reduces the test amount, and can achieve good economic and social benefits.

[0018] (3) The present invention simulates the process of cement mortar wrapping the aggregate, considers the influence of the aggregate particle size on the thickness of the cement mortar film, calculates the average thickness of the cement mortar film on the aggregate surface, and provides an accurate method for determining the specific surface area of the aggregate and copper tailings. According to the average film thickness of the cement mortar and the specific surface area of the aggregate and copper tailings, calculates the cement mortar dosage in the dry - hard concrete mixed with copper tailings, and calculates the cement dosage according to the water - cement ratio, providing a scientific and accurate calculation method for the optimal cement dosage of dry - hard concrete mixed with copper tailings.

[0019] (4)The present invention uses industrial waste copper tailings to replace part of the fine aggregate in dry - hard cement concrete, ensuring a high dosage of copper tailings in cement concrete, improving the resource utilization rate of copper tailings, saving resources, and being highly efficient and environmentally friendly. Detailed implementation manners

[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in combination with embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Embodiment

[0021] S1. The dry - hard cement concrete is composed of fine aggregate (particle size 0 - 5 mm), coarse aggregate (particle size 5 - 10 mm), copper tailings, water and cement. Perform performance tests on the raw materials. The cement selected is of grade P·O 42.5, and the specific surface area of the cement is 380 m 2 / kg. The test results of the raw materials of water and cement are shown in Table 1 below: Table 1 Density test of cement and water ; The designed strength of the dry - hard concrete is C30. According to the method specified in the standard, the water - cement ratio is determined to be 0.40.

[0022] S2. The dosages of fine aggregate, coarse aggregate and copper tailings in 1 cubic meter of dry - hard concrete are shown in Table 2 below: Table 2 Dosages of fine aggregate, coarse aggregate and copper tailings in 1 cubic meter of dry - hard concrete ; S3. Take samples of copper tailings, fine aggregate and coarse aggregate, and weigh their masses as shown in Table 3 below: Table 3 Mass of samples ; Immerse the copper tailings in water for 24 hours, then filter them, pour them into an iron cup, place absorbent paper at the bottom of the iron cup, separate the top with filter paper, put it into a centrifuge and rotate for 3 minutes, and weigh the mass of the copper tailings; the fine aggregate and coarse aggregate are also weighed according to this method after centrifugation. The masses of each sample after centrifugation are shown in Table 4 below: Table 4 Mass after immersion and centrifugation ; After drying in an oven, weigh the masses of each sample as shown in Table 5 below: Table 5 Dried mass ; Take a piece of stone with a particle size of 4 - 6 cm from the stone quarry, cut it into a regular cuboid aggregate, weigh it, and the mass is 20.3 g. The length of the cuboid aggregate is 1.2 cm, the width is 2.1 cm, and the height is 2.8 cm. The surface area of the cuboid aggregate is 2352 mm 2 , soak it in water for 24 hours and then filter it. Then pour it into an iron cup. Place absorbent paper at the bottom of the iron cup and separate it with filter paper at the top. Put it into a centrifuge and rotate for 3 minutes. Weigh the mass of the cuboid aggregate as 20.48 g. After drying it, the mass is 20.2 g. Calculate the water film thickness to be 12 um, that is, the water film thickness of fine aggregate, coarse aggregate, and copper tailings is all 12 um. According to the surface water film thickness and the volume of adsorbed water of the sample, calculate the specific surface area of each sample according to the following formula. The results are shown in Table 6: ; Table 6 Specific Surface Area of Materials ; Prepare a cement mortar according to a water - cement ratio of 0.40. Take 25 coarse aggregate samples, measure the volume and mass of each coarse aggregate sample, and calculate the specific surface area of each coarse aggregate sample according to the above method. The results are shown in Table 7 below: Table 7 Specific Surface Area of 25 Coarse Aggregate Samples ; Immerse 25 coarse aggregate samples in the cement mortar for 10 minutes, take them out and place them in a standard concrete curing room for 7 days. Take out the specimens and measure the volume of each coarse aggregate sample after being wrapped with the cement mortar. The results are shown in Table 8 below: Table 8 Volume of 25 Coarse Aggregate Samples after Being Wrapped with Cement Mortar ; Calculate the average mortar film thickness of the cement mortar wrapped around the coarse aggregate according to the following formula: ; The average mortar film thickness of the cement mortar wrapped around the coarse aggregate is the average mortar film thickness of the cement mortar wrapped around the fine aggregate and the cement mortar wrapped around the copper tailings.

[0023] According to the average mortar film thickness of the cement mortar wrapped around the coarse aggregate, the dosages of fine aggregate, coarse aggregate, and copper tailings in 1 cubic meter of dry - hard concrete, and the specific surface areas of fine aggregate, coarse aggregate, and copper tailings, calculate the dosages of cement and water according to the following formula: = 1.235 g / cm 3 ; = 530 kg; = 152 kg; = 378 kg; The dry - hard cement concrete mixture ratio of copper - tailings - doped prepared according to Table 9 below was used to prepare dry - hard cement concrete specimens doped with copper - tailings, and the compressive strength was tested. The results are shown in Table 10 below: Table 9 Dosage of raw materials for 1 cubic meter of dry - hard concrete ; Table 10 Compressive strength of dry - hard cement concrete doped with copper - tailings ; As can be seen from Table 10, the dry - hard cement concrete doped with copper - tailings prepared by the present invention meets the design strength requirements. The present invention determines the cement dosage of the dry - hard concrete doped with copper - tailings based on theoretical calculations, scientifically and effectively determines its optimal cement dosage, and can adapt to the changes of raw materials, timely adjust the optimal cement dosage, so as to ensure that the dry - hard concrete doped with copper - tailings has high quality, realize the resource utilization of industrial waste copper - tailings, and produce obvious economic benefits.

[0024] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for determining the mix proportion of copper-doped tailings dry-hardened concrete, characterized in that, It includes the following steps: S1. Determine the water-cement ratio according to the designed strength of the dry-hardened concrete; S2. Weigh 500 - 2000 g of copper tailings, 500 - 2000 g of fine aggregate, and 500 - 2000 g of coarse aggregate respectively. After soaking the three samples in water and filtering, place them in a sealed container in turn and centrifuge for 2 - 3 min, then weigh the mass of each sample after centrifugation; then dry and weigh the mass of each sample after drying. Calculate the specific surface area of each sample according to the water film thickness and the volume of adsorbed water on the surface of each sample; S3. Prepare the cement mortar according to the determined water-cement ratio. Weigh coarse aggregates with a quantity ≥ 20 pieces, measure the volume and mass of each coarse aggregate, and calculate the specific surface area of each coarse aggregate according to the method in step S2. Then immerse the coarse aggregates completely in the cement mortar, take them out for curing, then measure the volume of each coarse aggregate after being coated with the cement mortar, and calculate the average mortar film thickness of the weighed cement mortar-coated coarse aggregates; S4. According to the average mortar film thickness, the dosages of fine aggregate, coarse aggregate, and copper tailings in 1 cubic meter of dry-hardened concrete, and the specific surface area of each sample, calculate the dosages of cement and water in 1 cubic meter of dry-hardened concrete according to the following formula: ； ； ； ； In the formula: ρ j - Density of cement mortar, g / cm 3 ; α - water-cement ratio of dry-hardened concrete; ρ s - Density of water, g / cm 3 ; ρ n - Density of cement, g / cm 3 ; P j - Mass of cement mortar in semi-dry concrete, kg; u j - Average mortar film thickness of cement mortar coating coarse aggregate, μm; m 粗 - Mass of coarse aggregate in semi-dry concrete, kg; m 细 - Mass of fine aggregate in semi-dry concrete, kg; m w - Mass of copper tailings in semi-dry and hard concrete, kg; SA 粗 - Specific surface area of coarse aggregate m 2 / kg; SA 细 - Specific surface area of fine aggregate m 2 / kg; SA w - Specific surface area of copper tailings m 2 / kg; P s - Mass of water in the semi-dry concrete, kg; P n - Mass of cement in the semi-dry concrete, kg.

2. The method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: In step S2, the calculation formula for the specific surface area of each sample is as follows: ； In the formula: Specific surface area of SA-sample, m 2 / kg; m s - Mass of the sample after immersion in water, centrifugation and rotation, g; m g - Mass of the dried sample, g; m k - Mass of the sample during sampling, g; μ s - Water film thickness, μm; ρ s - Density of water, g / cm 3 .

3. The method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, wherein: In step S3, the calculation formula for the average mortar film thickness of the cement mortar-coated coarse aggregates is as follows: ； In the formula: u j - Average mortar film thickness of cement mortar coating coarse aggregate, μm; n - quantity of coarse aggregates; V i - Volume of the i-th sample in coarse aggregate before immersion in cement mortar, mm 3 ; VV i - Volume of the i-th sample of coarse aggregate after curing, mm 3 ; SA i - Specific surface area of the i-th sample in coarse aggregate, m 2 / kg; m i - Mass of the i-th sample in coarse aggregate, g.

4. A method for determining the mix ratio of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: In step S4, 1 cubic meter of dry-hardened concrete includes 520 - 580 kg of coarse aggregate, 820 - 900 kg of fine aggregate, and 380 - 420 kg of copper tailings.

5. A method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: In step S2, the soaking time ≥ 24 h.

6. A method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: In step S2, absorbent paper is placed at the bottom of the container.

7. A method for determining the mix ratio of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: In step S3, the immersion time in the cement mortar ≥ 10 min; the curing time ≥ 7 days.

8. A method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: The particle size of the coarse aggregate is 5 - 10 mm; the particle size of the fine aggregate is 0 - 5 mm.

9. A method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: The particle size of the copper tailings ≤ 1.18 mm, and the content of copper tailings with a particle size below 0.075 mm ≤ 40%.

10. A method for determining the mix proportion of copper-doped tailings dry-hard concrete according to claim 1, characterized in that: The water film thickness is 8 - 15 μm.

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