A method for determining the mix ratio of dry-hard concrete mixed with copper tailings

Abstract

The present invention belongs to the field of concrete preparation technology, and in particular, relates to a method for determining the mix ratio of dry-hard concrete blended with copper tailings. The method comprises the following steps: S1. Determining the water-cement ratio based on the prepared strength of the dry-hard concrete; S2. Calculating the specific surface area of ​​the sample; S3. Calculating the average cement mortar film thickness of the aggregate coated with cement mortar; and S4. Calculating the cement and water usage. This method utilizes industrial waste copper tailings as a resource. This method facilitates control of cement dosage during the mix design process, is highly efficient, and ensures the strength and stability of dry-hard cement concrete blended with copper tailings.

Description

Technical Field

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

[0002] According to statistics, hundreds of millions of tons of abandoned tailings are produced every year, and the recycling rate of tailings is only about 18.9%. The main way to deal with a large amount of unused tailings is to pile them up, which wastes a lot of land resources.

[0003] Small components such as arched slope protection, ditch covers, curbstones, and slope protection bricks are ancillary structures in highway construction. Traditional cast-in-place wet operations consume significant amounts of wood, cement, and water, leading to significant waste. Small component factories utilize centralized production, allowing for the recycling of both production water and formwork to reduce resource and energy consumption. These small components are typically manufactured using dry, hard concrete with a slump of less than 10mm. To ensure the strength and density of this dry, hard cement concrete, a high amount of fine aggregate is typically used. Copper tailings, with their uniform particle size and fine particle size, can replace fine aggregate, effectively realizing resource utilization.

[0004] Currently, the design of dry-hard concrete mixes primarily relies on empirically determining the initial cement dosage. Dry-hard concrete is then prepared by trial-mixing different cement dosages, and the final cement dosage is determined based on extensive testing. This method not only lacks theoretical basis and makes it difficult to obtain the optimal cement dosage, but also requires a large amount of testing, resulting in a significant waste of manpower and material resources. Therefore, a method for determining the mix ratio of dry-hard concrete mixed with copper tailings is urgently needed to address this issue. Summary of the Invention

[0005] To overcome the above-mentioned shortcomings of the prior art, the present invention provides a method for determining the mix ratio of dry-hard concrete mixed with copper tailings. The method determines the cement dosage of dry-hard concrete mixed with copper tailings based on theoretical calculations, scientifically and effectively determines the optimal cement dosage, and can adapt to changes in raw materials and adjust the optimal cement dosage in a timely manner.

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

[0007] A method for determining the mix ratio of dry-hard concrete mixed with copper tailings comprises the following steps:

[0008] S1. Determine the water-cement ratio based on the design strength of dry hard concrete;

[0009] S2. Weigh 500-2000 g of copper tailings, 500-2000 g of fine aggregate, and 500-2000 g of coarse aggregate, soak all three samples in water, filter them, and centrifuge them in a sealed container for 2-3 minutes. 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 based on the water film thickness on the surface of each sample and the volume of adsorbed water;

[0010] S3. Prepare cement mortar according to the water-cement ratio determined above. Since the particle size of coarse aggregate is large and easy to measure, weigh 20 or more 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, completely immerse the coarse aggregate in the cement mortar, remove it, and place it in a standard concrete curing room for curing. Remove the sample, measure the volume of each coarse aggregate after being coated with cement mortar, and calculate the average mortar film thickness of the weighed coarse aggregate coated with cement mortar;

[0011] S4. Based on the average mortar film thickness, the amount of fine aggregate, coarse aggregate, and copper tailings in one cubic meter of dry hard concrete, and the specific surface area of ​​each sample, calculate the amount of cement and water in one cubic meter of dry hard concrete according to the following formula:

[0012] ;

[0013] ;

[0014] ;

[0015] ;

[0016] Where:

[0017] ρ j -density of cement mortar, g / cm 3 ;

[0018] α-water-cement ratio of dry hard concrete;

[0019] ρ s -Density of water, g / cm 3 ;

[0020] ρ n - Density of cement, g / cm 3 ;

[0021] P j -Mass of cement mortar in 1 cubic meter of dry hard concrete, kg;

[0022] u j - Average cement mortar film thickness of coarse aggregate, μm;

[0023] m 粗 - Mass of coarse aggregate in 1 cubic meter of dry hard concrete, kg;

[0024] m 细 -Mass of fine aggregate in 1 cubic meter of dry hard concrete, kg;

[0025] m w -The mass of copper tailings in 1 cubic meter of dry hard concrete, kg;

[0026] SA 粗 -Specific surface area of ​​coarse aggregate m 2 / kg;

[0027] SA 细 -Specific surface area of ​​fine aggregate m 2 / kg;

[0028] SA w -Specific surface area of ​​copper tailings m 2 / kg;

[0029] P s -The mass of water in 1 cubic meter of dry hard concrete, kg;

[0030] P n -The mass of cement in 1 cubic meter of dry hard concrete, kg.

[0031] Preferably, in step S2, the calculation formula for the specific surface area of ​​each sample is as follows:

[0032] ;

[0033] Where:

[0034] SA-specific surface area of ​​the sample, m 2 / kg;

[0035] m s -The mass of the sample after centrifugation in water, g;

[0036] m g - Mass of the sample after drying, g;

[0037] m k -The mass of the sample at the time of sampling, g;

[0038] μ s -Water film thickness, μm;

[0039] ρ s -Density of water, g / cm 3 .

[0040] Preferably, in step S3, the calculation formula for the average mortar film thickness of the cement mortar wrapped around the coarse aggregate is as follows:

[0041] ;

[0042] Where:

[0043] u j - Average cement mortar film thickness of coarse aggregate, μm;

[0044] n - amount of coarse aggregate;

[0045] V i -The volume of the i-th sample of coarse aggregate before immersion in cement mortar, mm 3 ;

[0046] VV i - Volume of the i-th sample after coarse aggregate curing, mm 3 ;

[0047] SA i -Specific surface area of ​​the i-th sample in the coarse aggregate, m 2 / kg;

[0048] m i -The mass of the i-th sample in the coarse aggregate, g.

[0049] Preferably, in step S4, 1 cubic meter of dry hard concrete includes 520-580 kg of coarse aggregate, 820-900 kg of fine aggregate and 380-420 kg of copper tailings.

[0050] Preferably, in step S2, the immersion time is ≥ 24 h.

[0051] Preferably, in step S2, absorbent paper is placed at the bottom of the container to absorb moisture after centrifugation to avoid affecting subsequent weighing.

[0052] Preferably, in step S3, the immersion time in cement mortar is ≥10 min; and the curing time is ≥7 days.

[0053] Preferably, the particle size of the coarse aggregate is 5 to 10 mm; the particle size of the fine aggregate is 0 to 5 mm.

[0054] Preferably, the particle size of the copper tailings is ≤1.18 mm, wherein the content of copper tailings with a particle size of less than 0.075 mm is ≤40%.

[0055] Preferably, the water film thickness is 8-15 μm.

[0056] The advantages of the present invention are:

[0057] (1) The present invention utilizes industrial waste copper tailings as a resource. The method is easy to control the cement dosage during the proportion design process, has high efficiency, and ensures the strength and stability of the dry hard cement concrete mixed with copper tailings.

[0058] (2) The present invention addresses the defects existing in the design process of the mix ratio of dry-hard concrete mixed with copper tailings. By determining the specific surface area of ​​aggregate and copper tailings and the thickness of the cement mortar film formed by the coating of cement mortar through experiments, the optimal cement dosage of dry-hard concrete mixed with copper tailings is calculated, and the effect of cement is brought into play to the greatest extent. In addition, the cement dosage can be adjusted in real time through theoretical calculation according to the changes in the raw materials of aggregate and copper tailings, effectively bringing out the best effect of cement, improving the material performance of dry-hard concrete mixed with copper tailings, improving the efficiency of mix ratio design, greatly reducing the amount of experiments, and achieving better economic and social benefits.

[0059] (3) The present invention simulates the process of cement mortar coating aggregates and considers the influence of aggregate particle size on the thickness of cement mortar film to calculate the average thickness of cement mortar film on the aggregate surface, and provides an accurate method for determining the specific surface area of ​​aggregates and copper tailings. Based on the average thickness of cement mortar film and the specific surface area of ​​aggregates and copper tailings, the amount of cement mortar in dry-hard concrete mixed with copper tailings is calculated, and the cement dosage is calculated based on the water-cement ratio, thereby providing a scientific and accurate calculation method for the optimal cement dosage of dry-hard concrete mixed with copper tailings.

[0060] (4) The present invention uses industrial waste copper tailings to replace part of the fine aggregate in dry hard cement concrete, ensuring that the copper tailings have a higher content in the cement concrete, improving the resource utilization rate of the copper tailings, saving resources, and being efficient and environmentally friendly. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example

[0062] S1. Dry hard cement concrete is composed of fine aggregate (particle size 0-5mm), coarse aggregate (particle size 5-10mm), copper tailings, water and cement. The performance of the raw materials is tested. The cement is selected with a P·O 42.5 grade and a specific surface area of ​​380m 2 / kg. The results of the water and cement raw material tests are shown in Table 1 below:

[0063] Table 1 Cement and water density test

[0064] ;

[0065] The design strength of dry hard concrete is C30. According to the method specified in the specification, the water-cement ratio is determined to be 0.40.

[0066] S2. The amount of fine aggregate, coarse aggregate and copper tailings for 1 cubic meter of dry hard concrete is shown in Table 2 below:

[0067] Table 2 Amounts of fine aggregate, coarse aggregate, and copper tailings in 1 cubic meter of dry hard concrete

[0068] ;

[0069] S3. Take samples of copper tailings, fine aggregate, and coarse aggregate, and weigh their masses as shown in Table 3 below:

[0070] Table 3 Sample quality

[0071] ;

[0072] The copper tailings were soaked in water for 24 hours and then filtered. The tailings were then poured into an iron cup with absorbent paper placed at the bottom and filter paper placed at the top. The cup was then placed in a centrifuge and rotated for 3 minutes. The mass of the copper tailings was then weighed. The mass of the fine aggregate and coarse aggregate after centrifugation was also weighed in the same manner. The mass of each sample after centrifugation is shown in Table 4 below:

[0073] Table 4 Mass after immersion and centrifugation

[0074] ;

[0075] After drying in an oven, the mass of each sample was weighed as shown in Table 5 below:

[0076] Table 5 Drying quality

[0077] ;

[0078] Take a piece of stone with a particle size of 4-6 cm from the stone quarry and cut it into a regular rectangular aggregate. The mass is 20.3 g. The length, width and height of the rectangular aggregate are 1.2 cm, 2.1 cm and 2.8 cm respectively. The surface area of ​​the rectangular aggregate is 2352 mm. 2 , soak it in water for 24 hours, filter it, and then pour it into an iron cup. Pad the bottom of the iron cup with absorbent paper and separate the top with filter paper. Put it into a centrifuge and rotate it for 3 minutes. Weigh the mass of the rectangular aggregate to be 20.48g, and the mass after drying is 20.2g. The water film thickness is calculated to be 12um, that is, the water film thickness of fine aggregate, coarse aggregate and copper tailings is 12um. According to the water film thickness on the sample surface and the volume of adsorbed water, the specific surface area of ​​each sample is calculated according to the following formula. The results are shown in Table 6:

[0079] ;

[0080] Table 6 Specific surface area of ​​materials

[0081] ;

[0082] Cement mortar was prepared according to a water-cement ratio of 0.40. 25 coarse aggregate samples were taken, and the volume and mass of each coarse aggregate sample were measured. The specific surface area of ​​each coarse aggregate sample was calculated according to the above method. The results are shown in Table 7 below:

[0083] Table 7 Specific surface area of ​​25 coarse aggregate samples

[0084] ;

[0085] 25 coarse aggregate samples were immersed in cement mortar for 10 minutes, taken out and placed in a standard concrete curing room for 7 days. The samples were taken out and the volume of each coarse aggregate sample after being coated with cement mortar was measured. The results are shown in Table 8 below:

[0086] Table 8 Volume of 25 coarse aggregate samples coated with cement mortar

[0087] ;

[0088] The average mortar film thickness of the cement mortar wrapped with coarse aggregate is calculated according to the following formula:

[0089] ;

[0090] The average mortar film thickness of cement mortar wrapped around coarse aggregate is the average mortar film thickness of cement mortar wrapped around fine aggregate and cement mortar wrapped around copper tailings.

[0091] The amount of cement and water is calculated according to the following formula based on the average thickness of the cement mortar film on the aggregate, the amount of fine aggregate, coarse aggregate, and copper tailings in one cubic meter of dry hard concrete, and the specific surface area of ​​fine aggregate, coarse aggregate, and copper tailings:

[0092] =1.235g / cm 3 ;

[0093] =530kg;

[0094] =152kg;

[0095] =378kg;

[0096] According to the copper tailings-added dry-hard cement concrete mix ratio obtained in Table 9 below, copper tailings-added dry-hard cement concrete specimens were prepared and subjected to compressive strength tests. The results are shown in Table 10 below:

[0097] Table 9 Amount of raw materials for 1 cubic meter of dry hard concrete

[0098] ;

[0099] Table 10 Compressive strength of dry hard cement concrete mixed with copper tailings

[0100] ;

[0101] As shown in Table 10, the copper tailings-added dry-hard cement concrete prepared by the present invention meets the design strength requirements. The present invention determines the cement dosage for the copper tailings-added dry-hard concrete based on theoretical calculations, scientifically and effectively determining its optimal cement dosage. Furthermore, the present invention can adapt to changes in raw materials and adjust the optimal cement dosage in a timely manner, thereby ensuring that the copper tailings-added dry-hard concrete has high quality, realizing the resource utilization of industrial waste copper tailings, and generating significant economic benefits.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining the proportion of dry hard concrete mixed with copper tailings, characterized in that: The steps include: S1. Determine the water-cement ratio based on the design strength of dry hard concrete; S2. Weigh 500-2000 g of copper tailings, 500-2000 g of fine aggregate, and 500-2000 g of coarse aggregate, soak all three samples in water, filter them, and centrifuge them in a sealed container for 2-3 minutes. 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 based on the water film thickness on the surface of each sample and the volume of adsorbed water. The calculation formula for the specific surface area of ​​each sample is as follows: ； Where: SA-specific surface area of ​​the sample, m 2 / kg; m s -The mass of the sample after centrifugation in water, g; m g - Mass of the sample after drying, g; m k -The mass of the sample at the time of sampling, g; μ s -Water film thickness, μm; ρ s -Density of water, g / cm 3 ; S3. Prepare cement mortar according to the water-cement ratio determined above, weigh 20 or more 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, completely immerse the coarse aggregate in the cement mortar, remove it, and cure it. Then, measure the volume of each coarse aggregate after being coated with cement mortar, and calculate the average mortar film thickness of the weighed coarse aggregate coated with cement mortar. The calculation formula for the average mortar film thickness of the coarse aggregate coated with cement mortar is as follows: ； Where: u j - Average cement mortar film thickness of coarse aggregate, μm; n - amount of coarse aggregate; V i -The volume of the i-th sample of coarse aggregate before immersion in cement mortar, mm 3 ; VV i - Volume of the i-th sample after coarse aggregate curing, mm 3 ; SA i -Specific surface area of ​​the i-th sample in the coarse aggregate, m 2 / kg; m i - the mass of the i-th sample in the coarse aggregate, g; S4. Based on the average mortar film thickness, the amount of fine aggregate, coarse aggregate, and copper tailings in one cubic meter of dry hard concrete, and the specific surface area of ​​each sample, calculate the amount of cement and water in one cubic meter of dry hard concrete according to the following formula: ； ； ； ； Where: ρ j -density of cement mortar, g / cm 3 ; α-water-cement ratio of dry hard concrete; ρ s -Density of water, g / cm 3 ; ρ n - Density of cement, g / cm 3 ; P j -Mass of cement mortar in 1 cubic meter of dry hard concrete, kg; u j - Average cement mortar film thickness of coarse aggregate, μm; m 粗 - Mass of coarse aggregate in 1 cubic meter of dry hard concrete, kg; m 细 -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 -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 -The mass of water in 1 cubic meter of dry hard concrete, kg; P n -The mass of cement in 1 cubic meter of dry hard concrete, kg.

2. The method for determining the proportion of dry-hard concrete mixed with copper tailings according to claim 1, wherein: In step S4, one cubic meter of dry hard concrete includes 520-580 kg of coarse aggregate, 820-900 kg of fine aggregate and 380-420 kg of copper tailings.

3. The method for determining the proportion of dry-hard concrete mixed with copper tailings according to claim 1, wherein: In step S2, the immersion time is ≥ 24 h.

4. The method for determining the mix ratio of dry-hard concrete mixed with copper tailings according to claim 1, wherein: In step S2, absorbent paper is placed at the bottom of the container.

5. The method for determining the mix ratio of dry-hard concrete mixed with copper tailings according to claim 1, wherein: In step S3, the immersion time in cement mortar is ≥10 min; and the curing time is ≥7 days.

6. The method for determining the mix ratio of dry-hard concrete mixed with copper tailings according to claim 1, wherein: The particle size of coarse aggregate is 5-10 mm; the particle size of fine aggregate is 0-5 mm.

7. The method for determining the mix ratio of dry-hard concrete mixed with copper tailings according to claim 1, wherein: The particle size of the copper tailings is ≤1.18 mm, wherein the content of copper tailings with a particle size of less than 0.075 mm is ≤40%.

8. The method for determining the mix ratio of dry-hard concrete mixed with copper tailings according to claim 1, wherein: The water film thickness is 8-15 μm.

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