Iron tailing sand high-ductility fiber reinforced cement-based composite material and preparation method thereof
By using iron tailings sand instead of silica sand to prepare highly ductile fiber-reinforced cement-based composite materials, the problem of iron tailings sand being unused is solved, material performance improvement and cost reduction are achieved, and the sustainable utilization of resources is promoted.
Patent Information
- Application Number
- CN202510753206.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-06
- Publication Date
- 2025-09-02
AI Technical Summary
The cost of silica sand in existing ultra-high ductile fiber-reinforced cement-based materials is high, and iron tailings sand is not effectively utilized, resulting in environmental pollution and waste of resources. It is necessary to reduce costs and improve the comprehensive utilization rate of iron tailings sand.
Part or all of iron tailings sand is used to replace silica sand, combined with raw materials such as cement, fly ash, polyethylene fiber, etc., to prepare high-ductile fiber-reinforced cement matrix composite materials, and ensure material performance through specific stirring and curing processes.
The resource utilization of iron tailings sand has been achieved, the cost of materials is reduced, and the materials have excellent tensile strain hardening and compressive resistance to meet construction needs.
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Figure CN120573995A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of fiber-reinforced cement-based composite materials, and in particular to an iron tailings sand high-ductility fiber-reinforced cement-based composite material. Background Art
[0002] Ultra-high-ductility fiber-reinforced cementitious materials (ECC) typically achieve tensile strains exceeding 3%, over 300 times that of ordinary concrete. They also effectively control crack width, forming multiple fine cracks under direct tensile loads, with crack widths typically controlled to within 100 μm, resulting in superior mechanical properties and durability. ECC is currently widely used in a variety of practical projects. However, traditional ECC matrix materials primarily consist of cement, mineral admixtures, fibers, fine quartz sand, and admixtures. According to statistics, silica sand has the highest cost of all ECC components, accounting for 48.1%.
[0003] Iron tailings, the waste residue discharged after iron concentrate is separated from beneficiation plants, are one of my country's major industrial solid wastes. According to the "2021-2022 China Bulk Industrial Solid Waste Comprehensive Utilization Industry Development Report," the annual increase in tailings production in 2021 was approximately 1.308 billion tons, with a total accumulated tailings volume of 23.51 billion tons. The annual comprehensive utilization rate was the lowest, reaching only 33%. Among all tailings, iron tailings have the largest discharge and stockpiles, with an annual output of 543 million tons, accounting for 41.5% of the total tailings volume. However, due to the complex mineral composition, uneven distribution, and significant regional influences of iron tailings, the comprehensive utilization rate of iron tailings in my country is very low. At present, iron ore tailings that are not effectively utilized are usually landfilled, which not only occupies a large amount of land, but also causes soil pollution, water pollution and air pollution. In addition, some iron ore tailings contain heavy metals such as arsenic (As), lead (Pb) and manganese (Mn). These heavy metals pose a serious threat to the health of plants, animals and humans through various pathways such as bioaccumulation and environmental pollution.
[0004] Therefore, iron tailings can be used to replace silica sand to prepare cement-based materials, so as to improve the comprehensive utilization rate of iron tailings, reduce the pollution of iron tailings to the ecological environment, and at the same time reduce the preparation cost of ultra-high ductility fiber reinforced cement-based composite materials, which is of great significance to achieving sustainable utilization of resources and promoting the harmonious development of social economy and environment. Summary of the Invention
[0005] The present invention provides a method for preparing ultra-high ductility fiber-reinforced cement-based composite materials using iron tailings sand. The method partially or completely replaces silica sand with iron tailings sand, solves the problem of large-scale stacking of iron tailings sand, reduces the cost of preparing ultra-high ductility fiber-reinforced cement-based composite materials, is beneficial to the sustainable development of building materials, and at the same time maintains the required mechanical properties of the composite materials.
[0006] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which comprises the following raw materials: 556-573 parts of cement, 668-688 parts of fly ash, 331-341 parts of water, 0-445 parts of silica sand, 0-458 parts of iron tailings sand, 20 parts of fiber, and 2-3 parts of high-efficiency water reducer, wherein the iron tailings sand and the silica sand are not 0 at the same time.
[0007] Furthermore, the cement is ordinary Portland cement with a strength grade of 42.5.
[0008] Furthermore, the fly ash is low-calcium first-grade fly ash.
[0009] Furthermore, the silica sand is ultra-fine sand with an apparent density of 2.65 g / cm 3 .
[0010] Furthermore, the iron tailings sand is ultra-fine sand with an apparent density of 3.22 g / cm 3 .
[0011] Furthermore, the high-efficiency water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of more than 35%.
[0012] Furthermore, the fiber is polyethylene fiber, with a fiber length of 18 mm, a fiber diameter of 24 μm, a fiber tensile strength of 1560 MPa, a fiber tensile modulus of 116 GPa, and an elongation at break of 1-3%.
[0013] Furthermore, the weight ratio of the silica sand to the iron tailings sand is (0.2~3):1.
[0014] Furthermore, the weight ratio of the silica sand to the iron tailings sand is (0.2~0.5):1.
[0015] Another aspect of the present invention discloses a method for preparing the ultra-high ductility fiber reinforced ductile cement-based composite material, comprising the following preparation steps:
[0016] S1. Stir silicate cement, fly ash, silica sand and iron tailings sand at low speed for 1 min;
[0017] S2. Add the water reducer into the water and stir evenly to obtain a mixed solution for later use;
[0018] S3, stirring the dry mix obtained in S1 at a low speed for 1 min, then adding the mixed solution obtained in S2 and stirring at a low speed for 1 min, then stirring at a medium speed for 2 min, and finally stirring at a high speed for 2 min to obtain a uniform premix;
[0019] S4. Add polyethylene fiber to the premix obtained in S3 and stir for 1 minute at a low speed, 1 minute at a medium speed, and 3-4 minutes at a high speed to obtain a high-ductility fiber-reinforced cement-based composite material mixture of iron tailings sand.
[0020] S5. Pour the iron tailings sand high ductility fiber reinforced cement-based composite material mixture obtained in S4 into a mold, place it in a normal pressure environment with a temperature of 20℃±2℃ and a relative humidity controlled at more than 90%, and cure it for 28 days to obtain an iron tailings sand high ductility fiber reinforced cement-based composite material with a certain strength.
[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0022] 1. High-ductility fiber-reinforced cementitious composite materials are prepared by using iron tailings sand as fine aggregate and replacing silica sand with different mass additions. They have excellent tensile strain hardening and compressive properties, can meet the strength requirements of engineering projects, and can provide the high-ductility fiber-reinforced cementitious composite materials needed for current building structures.
[0023] 2. The composite material prepared by the present invention can not only realize the resource utilization of iron tailings sand, reduce the utilization of silica sand resources, and reduce the environmental pollution problems caused by the large-scale stacking of iron tailings sand, but also greatly reduce the preparation cost of high-ductility fiber-reinforced cement-based composite materials, thereby promoting the sustainable utilization of resources. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a diagram showing the variation of the cube flexural strength of the iron tailings sand fiber reinforced cement-based composite material in Examples 1-5.
[0025] Figure 2 This is a diagram showing the change in cube compressive strength of the iron tailings sand fiber reinforced cement-based composite material in Examples 1-5.
[0026] Figure 3-Figure 7 This is a graph showing the variation of the uniaxial tensile strength of the iron tailings sand fiber reinforced cement-based composite materials in Examples 1-5.
[0027] Figure 8 This is a graph showing the unit cost changes of the iron tailings sand fiber reinforced cement-based composite materials in Examples 1-5.
[0028] Figure 9 It is the change of unit energy consumption of the iron tailings sand fiber reinforced cement-based composite material in Examples 1-5. DETAILED DESCRIPTION
[0029] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0030] The present invention is further described in detail below with reference to specific embodiments.
[0031] An embodiment of the present invention discloses a high-ductility fiber-reinforced cement-based composite material of iron tailings sand, comprising the following raw materials: 556-573 parts of cement, 668-688 parts of fly ash, 331-341 parts of water, 0-445 parts of silica sand, 0-458 parts of iron tailings sand, 20 parts of fiber, and 2-3 parts of high-efficiency water reducer, wherein the iron tailings sand and silica sand are not 0 at the same time.
[0032] Optionally, the cement is ordinary Portland cement with a strength grade of 42.5.
[0033] Optionally, the fly ash is low-calcium first-grade fly ash.
[0034] Optionally, the silica sand is ultra-fine sand with an apparent density of 2.65 g / cm 3 .
[0035] Optionally, the iron tailings sand is ultra-fine sand with an apparent density of 3.22 g / cm 3 .
[0036] Optionally, the high-efficiency water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of more than 35%.
[0037] Optionally, the fiber is polyethylene fiber, with a fiber length of 18 mm, a fiber diameter of 24 μm, a fiber tensile strength of 1560 MPa, a fiber tensile modulus of 116 GPa, and an elongation at break of 1-3%.
[0038] Optionally, the weight ratio of the silica sand to the iron tailings sand is (0.2~3):1.
[0039] Optionally, the weight ratio of the silica sand to the iron tailings sand is (0.2~0.5):1.
[0040] Another embodiment of the present invention discloses a method for preparing the ultra-high ductility fiber-reinforced ductile cement-based composite material, comprising the following preparation steps:
[0041] S1. Stir silicate cement, fly ash, silica sand and iron tailings sand at low speed for 1 min;
[0042] S2. Add the water reducer into the water and stir evenly to obtain a mixed solution for later use;
[0043] S3, stirring the dry mix obtained in S1 at a low speed for 1 min, then adding the mixed solution obtained in S2 and stirring at a low speed for 1 min, then stirring at a medium speed for 2 min, and finally stirring at a high speed for 2 min to obtain a uniform premix;
[0044] S4. Add polyethylene fiber to the premix obtained in S3 and stir for 1 minute at a low speed, 1 minute at a medium speed, and 3-4 minutes at a high speed to obtain a high-ductility fiber-reinforced cement-based composite material mixture of iron tailings sand.
[0045] S5. Pour the iron tailings sand high ductility fiber reinforced cement-based composite material mixture obtained in S4 into a mold, place it in a normal pressure environment with a temperature of 20℃±2℃ and a relative humidity controlled at more than 90%, and cure it for 28 days to obtain an iron tailings sand high ductility fiber reinforced cement-based composite material with a certain strength.
[0046] The cement used in the embodiments of the present invention is ordinary Portland cement with a strength grade of 42.5; the fly ash is low-calcium first-grade fly ash; the silica sand is ultra-fine sand; the iron tailings sand is ultra-fine sand; the high-efficiency water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of more than 35%; the polyethylene fiber has a fiber length of 18 mm, a fiber diameter of 24 μm, a fiber tensile strength of 1560 MPa, a fiber tensile modulus of 116 GPa, and an elongation at break of 1-3%.
[0047] At the construction site, mix the above components according to the corresponding mass percentage and use a mixer to mix them into a homogeneous slurry before use. When used in concrete components, the usage method is the same as that of ordinary polyethylene fiber reinforced cement-based composite materials. There are no special requirements. The components adopt standard curing, and the curing age is generally 28 days.
[0048] The following are several examples of high-ductility fiber-reinforced cement-based composite materials made of iron ore tailings sand.
[0049] Example 1
[0050] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which is composed of the following raw materials in parts by weight: 556 parts of cement, 668 parts of fly ash, 331 parts of water, 445 parts of silica sand, 0 parts of iron tailings sand, 20 parts of fiber, and 3 parts of high-efficiency water reducer.
[0051] Example 2
[0052] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which is composed of the following raw materials in parts by weight: 560 parts of cement, 673 parts of fly ash, 333 parts of water, 336 parts of silica sand, 112 parts of iron tailings sand, 20 parts of fiber, and 3 parts of high-efficiency water reducer.
[0053] Example 3
[0054] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which is composed of the following raw materials in parts by weight: 565 parts of cement, 678 parts of fly ash, 335 parts of water, 226 parts of silica sand, 226 parts of iron tailings sand, 20 parts of fiber, and 3 parts of high-efficiency water reducing agent.
[0055] Example 4
[0056] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which is composed of the following raw materials in parts by weight: 569 parts of cement, 683 parts of fly ash, 338 parts of water, 114 parts of silica sand, 341 parts of iron tailings sand, 20 parts of fiber, and 3 parts of high-efficiency water reducer.
[0057] Example 5
[0058] The invention discloses an iron tailings sand high-ductility fiber-reinforced cement-based composite material, which is composed of the following raw materials in parts by weight: 573 parts of cement, 688 parts of fly ash, 341 parts of water, 0 parts of silica sand, 458 parts of iron tailings sand, 20 parts of fiber, and 2 parts of high-efficiency water reducer.
[0059] Specimens prepared using the above mix proportions, preparation, and standard curing conditions were tested for 28-day flexural strength, compressive strength, and uniaxial tensile strength, referring to JC / T 2461-2018, Test Method for Mechanical Properties of High-Ductility Fiber-Reinforced Cementitious Composites, GB / T 17671-2021, Test Method for Strength of Cement Mortar (ISO Method), and related literature. Each group for flexural strength and uniaxial tensile strength consisted of three specimens, and each group for compressive strength consisted of six specimens. The average of all test results was taken. The test results are shown in Tables 1-3 below. A comparison of the cost and energy consumption of high-ductility fiber-reinforced cementitious composites made with iron ore tailings sand using different mix proportions is shown in Table 4.
[0060] Table 1 Average flexural strength of high ductility fiber reinforced cementitious composites with different iron tailings sand ratios (e.g. Figure 1 shown).
[0061]
[0062] Table 2 Average compressive strength of high ductility fiber reinforced cement-based composites with different iron tailings sand ratios (e.g. Figure 2 shown).
[0063]
[0064] Table 3 Uniaxial tensile test results of high ductility fiber reinforced cementitious composites with different iron tailings sand ratios (e.g. Figure 3-7 shown).
[0065]
[0066] Table 4 Comparison of cost and energy consumption of high ductility fiber reinforced cementitious composites with different proportions of iron tailings sand (e.g. Figure 8 、 Figure 9 shown).
[0067]
[0068] From the above table we can see that:
[0069] The flexural strength and compressive strength of the iron tailings sand high-ductility fiber reinforced cement-based composite material prepared in the present invention are better than those in Example 1. As can be seen from Tables 1 and 2, the iron tailings sand in the present invention can effectively improve the compressive and flexural properties of the high-ductility fiber reinforced cement-based composite material.
[0070] As can be seen from Table 3, compared with Example 1, when the amount of iron tailings sand added in Example 5 is increased to completely replace silica sand, the peak stress, peak strain and ultimate elongation obtained in the uniaxial tensile test are greatly improved. This further illustrates that iron tailings sand can completely replace silica sand while ensuring mechanical properties.
[0071] As can be seen from Table 4, with the increase in the amount of iron tailings, the cost and energy consumption per square meter of high-ductility fiber-reinforced cement-based composite materials gradually decreased. In terms of cost, Examples 2-5 decreased by 4.7%, 9.5%, 14.4%, and 19.3% respectively compared with Example 1. In terms of energy consumption, Examples 2-5 decreased by approximately 0.04%, 0.11%, 0.15%, and 0.21% respectively compared with Example 1. Overall, with the increase in the amount of iron tailings, both cost and energy consumption showed a downward trend. Among them, the reduction in cost was more significant, while the reduction in energy consumption was relatively small.
[0072] In addition, it should be noted that, compared with Example 1, Example 2 uses iron tailings to replace a small portion of silica sand, but overall improvements in flexural strength, compressive strength, and tensile strength are achieved. Compared with Examples 2, 3, and 5, Example 4 still retains some silica sand, but the composite material of Example 4 has better performance in compressive strength.
[0073] In summary, the present invention provides a method for preparing high-ductility fiber-reinforced cement-based composite materials from iron tailings sand, which prepares cement-based composite materials with excellent ductility and mechanical properties, realizes the resource utilization of iron tailings sand, and effectively reduces the preparation cost of high-ductility fiber-reinforced cement-based composite materials.
[0074] 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 it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, technicians can still modify or replace the specific implementation methods of the present invention with equivalents, but these modifications or changes do not depart from the scope of protection of the pending claims of the present application.
Claims
1. A high ductility fiber reinforced cement-based composite material of iron tailings sand, characterized in that: The composite material comprises the following raw materials: 556-573 parts of cement, 668-688 parts of fly ash, 331-341 parts of water, 0-445 parts of silica sand, 0-458 parts of iron tailings sand, 20 parts of fiber, and 2-3 parts of high-efficiency water reducing agent, wherein the iron tailings sand and silica sand are not both 0.
2. The composite material according to claim 1, characterized in that The cement is ordinary Portland cement with a strength grade of 42.
5.
3. The composite material according to claim 1, characterized in that The fly ash is low-calcium first-grade fly ash.
4. The composite material according to claim 1, characterized in that The silica sand is ultra-fine sand with an apparent density of 2.65 g / cm 3 .
5. The composite material according to claim 1, characterized in that The iron tailings sand is ultra-fine sand with an apparent density of 3.22 g / cm 3 .
6. The composite material according to claim 1, characterized in that The high-efficiency water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of more than 35%.
7. The composite material according to claim 1, characterized in that The fiber is polyethylene fiber, with a fiber length of 18 mm, a fiber diameter of 24 μm, a fiber tensile strength of 1560 MPa, a fiber tensile modulus of 116 GPa, and a breaking elongation of 1-3%.
8. The composite material according to claim 1, characterized in that The weight ratio of the silica sand to the iron tailings sand is (0.2~3):
1.
9. The composite material according to claim 8, characterized in that The weight ratio of the silica sand to the iron tailings sand is (0.2~0.5):
1.
10. A method for preparing the ultra-high ductility fiber reinforced ductile cement-based composite material according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: S1. Stir silicate cement, fly ash, silica sand and iron tailings sand at low speed for 1 min; S2. Add the water reducer into the water and stir evenly to obtain a mixed solution for later use; S3, stirring the dry mix obtained in S1 at a low speed for 1 min, then adding the mixed solution obtained in S2 and stirring at a low speed for 1 min, then stirring at a medium speed for 2 min, and finally stirring at a high speed for 2 min to obtain a uniform premix; S4. Add polyethylene fiber to the premix obtained in S3 and stir for 1 minute at a low speed, 1 minute at a medium speed, and 3-4 minutes at a high speed to obtain a high-ductility fiber-reinforced cement-based composite material mixture of iron tailings sand. S5. Pour the iron tailings sand high ductility fiber reinforced cement-based composite material mixture obtained in S4 into a mold, place it in a normal pressure environment with a temperature of 20℃±2℃ and a relative humidity controlled at more than 90%, and cure it for 28 days to obtain an iron tailings sand high ductility fiber reinforced cement-based composite material with a certain strength.