Solid waste wave-absorbing concrete aggregate, preparation method and concrete

Abstract

The present invention relates to the field of building materials technology, and in particular to a solid waste wave-absorbing concrete aggregate, a preparation method, and concrete. The aggregate comprises, by weight, 18% to 22% coal gangue, 4% to 6% lithium slag, 8% to 12% steel slag with a particle size of 0 mm to 5 mm, 17% to 23% hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 40% to 50% carbonized steel slag with a particle size of 10 mm to 20 mm. This aggregate, preparation method, and concrete effectively address the problem of poor stability, resulting in higher concrete strength and improved wave-absorbing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a solid waste wave-absorbing concrete aggregate, a preparation method and concrete. Background Art

[0002] Absorbent concrete (also known as cement-based composite absorbing material) is a building material with the ability to absorb electromagnetic waves, created by incorporating absorbers into ordinary cement concrete or by employing specialized structural designs. It boasts advantages such as energy conservation and environmental protection, affordability, versatility, and adaptability, while also avoiding the drawbacks of coating materials, such as easy shedding and damage. However, due to the complex composition of cement, the selection of different absorbers requires consideration of their compatibility with the cement matrix, as well as the impact of physical and chemical reactions between the absorbers and the cementitious materials on their absorption, performance, and mechanical properties.

[0003] Magnetic absorbers are primarily composed of iron oxides (Fe₃O₄, Fe₂O₃, etc.) and ferrites (Mn-Zn ferrite, Ni-Zn ferrite, etc.). Magnetic absorbers have high magnetic permeability and generally exhibit good absorption performance at low frequencies. Conductive absorbers (such as carbon powder and fibers) exhibit excellent electrical conductivity. When added to concrete, they form conductive chains or networks, absorbing electromagnetic waves through electric field interaction. Conductive absorbers used in concrete are generally carbon-based materials, characterized by their low specific gravity. However, excessive addition can cause significant reflection of incident waves, reducing absorption performance and also affecting the concrete's performance. Dielectric absorbers, such as manganese dioxide and barium titanate ceramics, typically have a large dielectric constant and primarily absorb electromagnetic waves through dielectric and interfacial polarization. However, due to their relatively low loss capacity, dielectric loss agents do not significantly improve the absorption performance of cement concrete. Currently, research on dielectric absorbers filled with cement-based composite absorbers is limited.

[0004] In the prior art, a Chinese invention patent document with publication number CN114105567A and publication date March 1, 2022 has been proposed. The technical solution disclosed in the patent document is as follows: concrete that absorbs electromagnetic waves is prepared from industrial solid waste. This type of concrete consists of 15-25% by weight of powder, 25-35% of fine aggregate, 35-45% of coarse aggregate, 6-10% of liquid and 0.1-0.3% of fiber. Slag and fly ash are added to the concrete, and steel slag is used as coarse aggregate; polypropylene fiber is added to enhance the crack resistance of the concrete.

[0005] The above technical solution may cause the following problems during actual use:

[0006] Steel slag, used as coarse aggregate, is produced using a heat-suffocating process. This process utilizes the residual heat of the slag and the physical and chemical reactions it undergoes when it comes into contact with water, causing alkaline oxides like CaO and MgO to react and produce hydroxides. However, the slag's alkalinity remains essentially unchanged, resulting in poor concrete stability. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention proposes a solid waste absorbing concrete aggregate, a preparation method and concrete, which can effectively solve the problem of poor stability, and the concrete has higher strength and better absorbing performance.

[0008] The present invention is achieved by adopting the following technical solutions:

[0009] A solid waste wave-absorbing concrete aggregate comprises, by weight percentage, 18% to 22% of coal gangue, 4% to 6% of lithium slag, 8% to 12% of steel slag with a particle size of 0 mm to 5 mm, 17% to 23% of hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 40% to 50% of carbonized steel slag with a particle size of 10 mm to 20 mm.

[0010] The particle size of the coal gangue is 0 mm to 5 mm.

[0011] The particle size of the lithium slag is 45 μm and the sieve residue is 30% to 50%.

[0012] The hydrophobic treatment specifically refers to: soaking steel slag with a particle size of 5mm to 10mm in a hydrophobic agent, fully absorbing it and then drying it.

[0013] The carbonization treatment specifically refers to: placing steel slag with a particle size of 10mm~20mm in an autoclave, autoclaving it with water vapor at a temperature of 175℃~185℃ for 3h~5h, releasing steam and introducing 0.9MPa~1.1MPa cement kiln tail gas, and curing it for 3h~5h.

[0014] A method for preparing solid waste wave-absorbing concrete aggregate comprises the following steps:

[0015] Step S1. The gangue and steel slag are crushed and the lithium slag is ground;

[0016] Step S2. The crushed slag is screened, the slag with a particle size of 5mm~10mm is hydrophobicized, and the slag with a particle size of 10mm~20mm is carbonized;

[0017] Step S3: Evenly mix the coal gangue, steel slag and lithium slag.

[0018] A solid waste wave-absorbing concrete comprises the solid waste wave-absorbing concrete aggregate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention breaks with conventional thinking and uses solid wastes, namely coal gangue, lithium slag and steel slag, which are clearly prohibited from use in the general Portland cement standard GB175-2023, as concrete aggregates. Through the mutual coordination of various substances, the configuration of high-strength wave-absorbing concrete can be achieved.

[0021] Specifically, the coal gangue is crushed into fine aggregate and can be evenly distributed in the concrete, making the concrete absorbent and conductive, further enhancing the wave absorption effect; the steel slag is porous and has wave absorption properties. At the same time, the iron in the steel slag is conductive, which can enhance the wave absorption effect; the lithium slag can enter the interior of the coal gangue and steel slag, and can also improve the conductivity.

[0022] Steel slag can enhance the reactivity of coal gangue by adjusting its pH and ion concentration, increasing the number of reactive functional groups such as hydroxyl and carboxyl groups on its surface. Furthermore, trace elements in steel slag can act as catalysts or active centers, further stimulating the reactivity and stability of coal gangue. Furthermore, coal gangue and steel slag complement each other in terms of hardness, providing suitable aggregate strength for concrete.

[0023] Lithium slag also exhibits significant pozzolanic activity. When ground, it can partially fill aggregate pores, improve particle distribution, enhance concrete workability, and contribute to strength development. Furthermore, lithium slag particles provide nucleation sites for cement hydration products, facilitating their attachment and enhancing the nucleation effect. Simultaneously, the calcium hydroxide generated by hydration of the steel slag reacts with the active aluminum and silicon in the coal gangue and lithium slag, collectively enhancing the early strength of concrete.

[0024] 2. The aggregate of the present invention can achieve good particle gradation and the most compact packing by controlling the proportion of each material, thereby reducing the amount of cementitious materials in concrete and improving the comprehensive performance of concrete.

[0025] 3. The present invention treats steel slag of different particle sizes separately. The steel slag with a particle size of 5mm-10mm is subjected to hydrophobic treatment, which can retain more of its internal porous structure and is more conducive to the improvement of wave absorption performance; the steel slag with a particle size of 10mm-20mm is subjected to carbonization treatment to react the alkaline oxides into carbonates. While consuming the calcium oxide and magnesium oxide in the steel slag, it can reduce the alkalinity and improve the stability, which can solve the problem of aggregate stability. At the same time, it absorbs CO2 and achieves the effect of carbon fixation.

[0026] The mutual coordination of steel slag of different particle sizes can play a greater role and is more conducive to improving the mechanical properties and wave absorption properties of concrete.

[0027] 4. The hydrophobic treatment method is simple, and the steel slag treated by the hydrophobic treatment will have some hydrophobic agent remaining on the surface or in the internal voids. The hydrophobic agent remaining on the surface can effectively reduce the water demand of the steel slag, especially the fine steel slag, and improve the strength of the concrete; the hydrophobic agent remaining in the internal voids can ensure the integrity of the voids and improve the wave absorption performance of the concrete.

[0028] 5. In the carbonization process of the present invention, after forming tobermorite by utilizing the calcium-silicon ratio of steel slag, the carbonized tobermorite can make the carbonization product more evenly distributed in the steel slag, while improving the carbonization carbon fixation rate and ensuring stability.

[0029] At the same time, the carbonized steel slag also produces some hydrated calcium silicate and calcium carbonate during the autoclaving process. As homogeneous materials, the formed hydrated calcium silicate can serve as a crystal nucleus to activate the uncarbonized part, which can effectively promote the hydration of the hydrophobic treated steel slag, improve the performance of the aggregate, and achieve an improvement in the comprehensive performance of the concrete.

[0030] 6. The present invention introduces the flue gas from the cement kiln into the carbonization treatment of steel slag, which can fully utilize existing resources. DETAILED DESCRIPTION

[0031] Example 1

[0032] This embodiment includes a solid waste wave-absorbing concrete aggregate comprising, by weight, 18% coal gangue, 4% lithium slag, 8% steel slag with a particle size of 0 mm to 5 mm, 20% hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 50% carbonized steel slag with a particle size of 10 mm to 20 mm. The coal gangue has a particle size of 0 mm to 5 mm. The lithium slag has a particle size of 45 μm and a sieve residue of 30% to 50%.

[0033] The hydrophobic treatment specifically refers to: placing steel slag with a particle size of 5mm~10mm into a hydrophobic agent for soaking, fully absorbing and then drying. The hydrophobic agent can be a silicone resin or a fluorocarbon polymer, etc. The carbonization treatment specifically refers to: placing steel slag with a particle size of 10mm~20mm into an autoclave, steam-pressing it at a temperature of 175℃~185℃ for 3h~5h, releasing steam and introducing 0.9MPa~1.1MPa of cement kiln tail gas, and curing for 3h~5h. The kiln tail gas is the exhaust gas from the calcination of clinker in a cement plant, which is about 150℃ and contains about 25% CO2.

[0034] The method for preparing the above-mentioned solid waste wave-absorbing concrete aggregate comprises the following steps:

[0035] Step S1. Crush the coal gangue and steel slag separately, and grind the lithium slag into fine powder.

[0036] Step S2: Screening the crushed slag, performing hydrophobic treatment on the slag with a particle size of 5 mm to 10 mm, and carbonizing the slag with a particle size of 10 mm to 20 mm.

[0037] Step S3: Evenly mix the coal gangue, steel slag and lithium slag.

[0038] Example 2

[0039] This embodiment includes a solid waste wave-absorbing concrete aggregate comprising, by weight, 22% coal gangue, 6% lithium slag, 12% steel slag with a particle size of 0 mm to 5 mm, 20% hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 40% carbonized steel slag with a particle size of 10 mm to 20 mm. The coal gangue has a particle size of 0 mm to 5 mm. The lithium slag has a particle size of 45 μm and a sieve residue of 30% to 50%.

[0040] Among them, the hydrophobic treatment method, carbonization treatment method and preparation method of solid waste absorbing concrete aggregate are consistent with the methods in Example 1.

[0041] Example 3

[0042] This embodiment includes a solid waste wave-absorbing concrete aggregate comprising, by weight, 20% coal gangue, 5% lithium slag, 10% steel slag with a particle size of 0 mm to 5 mm, 17% hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 48% carbonized steel slag with a particle size of 10 mm to 20 mm. The coal gangue has a particle size of 0 mm to 5 mm. The lithium slag has a particle size of 45 μm and a sieve residue of 30% to 50%.

[0043] Among them, the hydrophobic treatment method, carbonization treatment method and preparation method of solid waste absorbing concrete aggregate are consistent with the methods in Example 1.

[0044] Example 4

[0045] This embodiment includes a solid waste wave-absorbing concrete aggregate comprising, by weight, 19% coal gangue, 6% lithium slag, 11% steel slag with a particle size of 0 mm to 5 mm, 23% hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 41% carbonized steel slag with a particle size of 10 mm to 20 mm. The coal gangue has a particle size of 0 mm to 5 mm. The lithium slag has a particle size of 45 μm and a sieve residue of 30% to 50%.

[0046] Among them, the hydrophobic treatment method, carbonization treatment method and preparation method of solid waste absorbing concrete aggregate are consistent with the methods in Example 1.

[0047] Concrete was made using the solid waste wave-absorbing concrete aggregates in Examples 1 to 4. The concrete mix ratio is shown in Table 1 below:

[0048] Table 1 Concrete mix ratio kg / m 3

[0049]

[0050] Calcium carbonate was used as a common aggregate and concrete was prepared using the mix ratios shown in Table 1 to form a control group. The concretes prepared in Examples 1 to 4 were compared with the concrete prepared in the control group to test indicators such as carbon fixation rate, strength, and wave absorption performance. The test results are shown in Table 2 below:

[0051] Table 2 Concrete performance test

[0052]

[0053] The carbon fixation rate is calculated based on the increase in slag mass. The compressive strength is measured in accordance with GB / T50107-2010 "Concrete Strength Test and Assessment Standard." The reflectivity is measured in accordance with GJB 2038-94 "Test Method for Reflectivity of Radar Absorbing Materials."

[0054] It can be seen from the above test data that the concrete prepared using the concrete aggregate of the present application has more stable performance, higher strength and better wave absorption performance.

[0055] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical solutions and technical concepts of the present invention without creative mental work, which all fall within the scope of protection of the present invention.

Claims

1. A solid waste wave-absorbing concrete aggregate, characterized by: Calculated by weight percentage, it includes 18% to 22% of coal gangue, 4% to 6% of lithium slag, 8% to 12% of steel slag with a particle size of 0 mm to 5 mm, 17% to 23% of hydrophobic steel slag with a particle size of 5 mm to 10 mm, and 40% to 50% of carbonized steel slag with a particle size of 10 mm to 20 mm; the particle size of the coal gangue is 0 mm to 5 mm; the particle size of the lithium slag is 45 μm and the sieve residue is 30% to 50%.

2. The solid waste wave-absorbing concrete aggregate according to claim 1, characterized in that: The hydrophobic treatment specifically refers to: soaking steel slag with a particle size of 5mm to 10mm in a hydrophobic agent, fully absorbing it and then drying it.

3. The solid waste wave-absorbing concrete aggregate according to claim 1, characterized in that: The carbonization treatment specifically refers to: placing steel slag with a particle size of 10mm~20mm in an autoclave, autoclaving it with water vapor at a temperature of 175℃~185℃ for 3h~5h, releasing the steam and introducing 0.9MPa~1.1MPa cement kiln tail gas, and curing for 3h~5h.

4. The method for preparing solid waste wave-absorbing concrete aggregate according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1. The gangue and steel slag are crushed and the lithium slag is ground; Step S2. The crushed slag is screened, the slag with a particle size of 5mm~10mm is hydrophobicized, and the slag with a particle size of 10mm~20mm is carbonized; Step S3: Evenly mix the coal gangue, steel slag and lithium slag.

5. A solid waste absorbing concrete, characterized by: The invention comprises the solid waste wave-absorbing concrete aggregate as described in any one of claims 1 to 3.

Images