A solid waste-based early-strength concrete mineral admixture and preparation method thereof

Abstract

The present invention discloses a solid waste-based early-strength concrete mineral admixture and a preparation method thereof. The admixture comprises the following components by mass percentage: 8%-30% early-strength agent, 40%-70% water-quenched blast furnace granulated slag, 10%-25% water-quenched manganese slag, 5%-20% first-class fly ash, and 5%-15% ferrosilicon alloy dust removal ash. The early-strength agent is composed of 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-aluminum fly ash, and 20% desulfurization ash. First, the early-strength agent is prepared, calcined, and ground; secondly, the water-quenched blast furnace granulated slag and the water-quenched manganese slag are ground; finally, the components are mixed in proportion to prepare the admixture. The mineral admixture provided by the present invention, by organically combining multiple industrial solid wastes and applying them to concrete production, can not only enhance the early and long-term strength and durability of concrete, but also greatly reduce the amount of cement used in concrete, thereby achieving low-carbon development of the concrete industry.

Description

Technical Field

[0001] The present invention relates to the technical field of building material additives, in particular to a solid waste-based early-strength concrete mineral admixture and a preparation method thereof. Background Art

[0002] Carbon reduction in the construction industry and building energy use is the key to achieving "sustainable development." In 2020, my country's total carbon emissions from the construction sector reached 5.08 billion tons of CO2, accounting for 50.9% of the country's total carbon emissions. Among them, carbon emissions from the production of building materials produced 2.82 billion tons of CO2, the highest proportion and corresponding to about 30% of the country's total carbon emissions. Cement, as the dominant material, has carbon emissions of 1.23 billion tons of CO2. Concrete, as the main carrier of cement, has a significant high carbon footprint. At the same time, industrial production and urban life generate a large amount of solid waste (such as fly ash, steel slag, slag, construction waste, etc.). The treatment of these wastes has become a difficult problem in environmental governance. Applying industrial solid waste to building materials industries such as concrete to reduce cement usage has become the main means of resource utilization.

[0003] In the current existing technology, the mineral admixtures used in concrete are mainly slag powder, steel slag powder, fly ash, stone powder, etc. However, with the increase in the amount of solid waste added, many problems have arisen in the working performance and mechanical properties of concrete, such as low early strength and poor working performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a concrete mineral admixture based on solid waste and a preparation method thereof, which can efficiently utilize a variety of solid wastes, improve the working performance, mechanical properties and durability of concrete, while reducing production costs and environmental pollution, thereby solving the problems in the background technology.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] A solid waste-based early-strength concrete mineral admixture comprises the following components, measured in percentage by mass: 8%-30% of an early-strength agent, 40%-70% of water-quenched blast furnace granulated slag, 10%-25% of water-quenched manganese slag, 5%-20% of primary fly ash, and 5%-15% of ferrosilicon alloy dust removal ash.

[0007] Furthermore, the early strength agent includes the following components: 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-aluminum fly ash and 20% desulfurization ash.

[0008] A method for preparing a solid waste-based early-strength concrete mineral admixture includes the above-mentioned solid waste-based early-strength concrete mineral admixture, and the specific steps are as follows:

[0009] Step S1. Prepare an early strength agent by preparing 35% by mass of kaolin, 20% by mass of sodium sulfate, 8% by mass of iron tailings, 7% by mass of coal powder, 10% by mass of high-aluminum fly ash, and 20% by mass of desulfurized ash. Then, calcine the early strength agent and grind the calcined early strength agent to a powder specific surface area of ≥420m 2 / kg;

[0010] Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg;

[0011] Step S3. 8%-30% of an early strength agent, 40%-70% of water-quenched blast furnace granulated slag, 10%-25% of water-quenched manganese slag, 5%-20% of primary fly ash, and 5%-15% of ferrosilicon alloy dust ash are fully mixed according to mass fractions to prepare a solid waste-based early strength concrete mineral admixture.

[0012] Furthermore, in step S1, the calcination temperature of the early strength agent is 1300° C.-1350° C.

[0013] The beneficial effects of the present invention are as follows:

[0014] 1. The present invention utilizes kaolin, sodium sulfate, iron ore tailings, coal powder, high-alumina fly ash, and desulfurization ash, whose primary chemical components are Al, Ca, Si, and S. After calcination, their primary mineral components are dicalcium silicate and anhydrous calcium sulfate, similar to the mineral composition of cement clinker. However, their activity-stimulating effect is superior to that of Portland cement clinker. Therefore, these mineral admixtures can be used as early strength accelerators for mineral admixtures, fully stimulating the gelling activity of silicomanganese slag and blast furnace water-quenched granulated slag. This reduces the amount of cement added to concrete while generating stable CSH gel, CASH gel, and AFt. The amount of complex salt minerals in the hydration products is higher than that of the cement they replace, making the hydration product particles finer, thereby increasing the density of the interfacial reaction transition zone and creating a denser cementitious network structure within the concrete. Mineral admixtures that do not participate in the reaction accumulate between the aggregate and the slurry, improving the structure of weak areas and thereby enhancing the mechanical properties of the concrete.

[0015] 2. The present invention conducts dual physical and chemical stimulation on multiple industrial solid wastes, fully stimulating their gelling activity, while achieving the morphological effect and micro-aggregate effect between material particles, which can effectively improve the working performance of concrete. The concrete produced has good durability, low price, simple process, and is green and environmentally friendly.

[0016] 3. The present invention provides a solid waste-based early-strength concrete mineral admixture for preparing concrete. Since its mineral composition is similar to that of cement clinker and has a better early activation effect on blast furnace slag powder, the amount of cement replaced in concrete can reach 50%-90%, which plays a significant role in reducing carbon emissions. The active minerals in this mineral admixture are mainly dicalcium silicate, which has a low hydration heat. At the same time, the mineral composition of anhydrous calcium sulfate and other minerals has a more obvious effect on the early activation of blast furnace slag powder, and the early hydration reaction is milder than that of ordinary cement concrete, which is more conducive to the use of large-volume concrete projects and reduces the risk of concrete cracking. DETAILED DESCRIPTION

[0017] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] A solid waste-based early-strength concrete mineral admixture comprises, by mass percentage, 8%-30% of an early-strength agent, 40%-70% of water-quenched blast furnace granulated slag, 10%-25% of water-quenched manganese slag, 5%-20% of primary fly ash, and 5%-15% of ferrosilicon alloy dust removal ash.

[0019] Among them: the mass percentage of the raw materials of the early strength agent is: kaolin 35%, sodium sulfate 20%, iron tailings 8%, coal powder 7%, high-alumina fly ash 10%, and desulfurization ash 20%.

[0020] Example 1

[0021] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps:

[0022] Step S1. The early strength agent is prepared according to the following mass percentages: kaolin 35%, sodium sulfate 20%, iron tailings 8%, coal powder 7%, high-aluminum fly ash 10%, desulfurization ash 20%, and then calcined. The calcined early strength agent is ground to a powder with a specific surface area of ≥420m 2 / kg.

[0023] Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg;

[0024] Step S3. Weigh 10% of the early strength agent, 70% of the water-quenched blast furnace granulated slag, 10% of the water-quenched manganese slag, 5% of the first-grade fly ash, and 5% of the ferrosilicon alloy dust ash according to the mass percentage, and mix them thoroughly to prepare a solid waste-based early strength concrete mineral admixture.

[0025] Example 2

[0026] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps:

[0027] Step S1. The early strength agent is prepared according to the following mass percentages: kaolin 35%, sodium sulfate 20%, iron tailings 8%, coal powder 7%, high-aluminum fly ash 10%, desulfurization ash 20%, and then calcined. The calcined early strength agent is ground to a powder with a specific surface area of ≥420m 2 / kg.

[0028] Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg;

[0029] Step S3. Weigh 15% of the early strength agent, 60% of the water-quenched blast furnace granulated slag, 10% of the water-quenched manganese slag, 7% of the first-class fly ash, and 8% of the ferrosilicon alloy dust ash according to the mass percentage, and mix them thoroughly to prepare the solid waste-based early strength concrete mineral admixture.

[0030] Example 3

[0031] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps:

[0032] Step S1. The early strength agent is prepared according to the following mass percentages: kaolin 35%, sodium sulfate 20%, iron tailings 8%, coal powder 7%, high-aluminum fly ash 10%, desulfurization ash 20%, and then calcined. The calcined early strength agent is ground to a powder with a specific surface area of ≥420m 2 / kg.

[0033] Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg;

[0034] Step S3. Weigh 20% of the early strength agent, 50% of the water-quenched blast furnace granulated slag, 10% of the water-quenched manganese slag, 10% of the first-class fly ash, and 10% of the ferrosilicon alloy dust ash according to the mass percentage, and mix them thoroughly to prepare a solid waste-based early strength concrete mineral admixture.

[0035] Example 4

[0036] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps:

[0037] Step S1. The early strength agent is prepared according to the following mass percentages: kaolin 35%, sodium sulfate 20%, iron tailings 8%, coal powder 7%, high-aluminum fly ash 10%, desulfurization ash 20%, and then calcined. The calcined early strength agent is ground to a powder with a specific surface area of ≥420m 2 / kg.

[0038] Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg;

[0039] Step S3. Weigh 25% of the early strength agent, 55% of the water-quenched blast furnace granulated slag, 10% of the water-quenched manganese slag, 5% of the first-class fly ash, and 5% of the ferrosilicon alloy dust ash according to the mass percentage, and mix them thoroughly to prepare the solid waste-based early strength concrete mineral admixture.

[0040] Experimental comparative demonstration

[0041] The solid waste-based early-strength concrete mineral admixture obtained in Example 1-4 was used to prepare concrete according to the following mix ratio: cement 190 kg / m 3 , admixture 190 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121 kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0042] Comparative Example 1

[0043] A common concrete mineral admixture is selected, wherein the admixture is composed of the following raw materials by mass fraction: fly ash 50%, slag powder 35%, and steel slag powder 15%, wherein the fly ash is Class I ash in accordance with GB / T1596-2017 "Fly ash for cement and concrete", the slag powder is S95 grade, and the powder specific surface area is 420 m 2 / kg, the specific surface area of steel slag powder is 400m 2 / kg.

[0044] Ordinary concrete was prepared according to the following mix ratio: cement 190 kg / m 3 , admixture 190 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121 kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0045] Comparative Example 2

[0046] The solid waste-based early-strength concrete mineral admixture obtained in Example 1 was used to prepare concrete according to the following mix ratio: cement 175 kg / m 3 , admixture 205 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0047] Comparative Example 3

[0048] The solid waste-based early-strength concrete mineral admixture obtained in Example 2 was used to prepare concrete according to the following mix ratio: cement 155 kg / m 3 , admixture 225 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121 kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0049] Comparative Example 4

[0050] The solid waste-based early-strength concrete mineral admixture obtained in Example 3 was used to prepare concrete according to the following mix ratio: cement 135 kg / m 3 , admixture 245 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121 kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0051] Comparative Example 5

[0052] The solid waste-based early-strength concrete mineral admixture obtained in Example 4 was used to prepare concrete according to the following mix ratio: cement 115 kg / m 3 , admixture 265 kg / m 3 , sand 723kg / m 3 、Stone 1096 kg / m 3 , water 121 kg / m 3 , polycarboxylate high-efficiency water reducer 5.05 kg / m 3 .

[0053] The raw materials in Examples 1-4 and Comparative Examples 1-5 were placed in a concrete mixer and stirred evenly. The mixture was poured into a 100mm×100mm×100mm mold at a temperature of 20±5°C and a relative humidity of not less than 60%. The mixture was placed on a concrete vibration table for vibration molding and its relevant properties were tested. The prepared concrete test blocks were placed under standard curing conditions of a curing temperature of 20°C±2°C and a relative humidity of not less than 95% for 24 hours before demolding. The blocks were then placed in a constant temperature and humidity curing box at a curing temperature of 20°C±2°C and a relative humidity of not less than 95% for curing to 3d and 28d. The compressive strength of the concrete was tested, and the 56d chloride ion permeability resistance of the concrete and the 90d shrinkage rate and carbonization depth of the concrete were tested. The above test results are shown in Table 1:

[0054] Table 1 Test results

[0055] serial number Slump / mm Expansion / mm Liquidity 7d compressive strength / MPa 28d compressive strength / MPa 56d Chloride ion permeability resistance / C <![CDATA[90d shrinkage rate / × 10 -6 > 90d carbonization depth / mm Example 1 200 595 good 32.2 45.2 225 92 0.8 Example 2 190 590 good 33.7 46.4 230 100 0.8 Example 3 210 602 good 31.5 43.1 260 115 1.0 Example 4 205 597 good 35.3 46.8 220 96 0.8 Comparative Example 1 210 599 good 31.1 44.3 525 165 1.5 Comparative Example 2 185 588 good 33.5 46.2 220 110 0.8 Comparative Example 3 195 600 good 35.2 46.7 225 103 0.8 Comparative Example 4 200 598 good 34.7 44.9 265 95 0.9 Comparative Example 5 195 596 good 35.6 47.6 200 86 0.7

[0056] As shown in Table 1, the solid waste-based early-strength concrete mineral admixture of the present invention significantly improves the workability, strength, and durability of concrete. Its specific dosage can be adjusted according to the concrete design parameters. The above specific examples are only preferred and are not intended to limit the implementation methods.

[0057] In Example 3, the 50% content of water-quenched blast furnace granulated slag is the lowest among Examples 1-4, which results in its parameters being slightly worse than those of Examples 1, 2 and 4. Similarly, the parameters of Comparative Example 4 are slightly worse than those of Comparative Examples 2, 3 and 5, but still better than Comparative Example 1.

[0058] In summary, the solid waste-based early-strength concrete mineral admixture provided by the present invention can replace a large amount of cement in concrete, reducing carbon emissions while also improving the compressive strength and durability of concrete. Compared to existing market types, this solid waste-based early-strength concrete mineral admixture exhibits high early strength and excellent durability, providing significant benefits and effectively resolving the problem of low early strength in concrete, which hinders construction.

[0059] The basic principles, main features and advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A solid waste-based early-strength concrete mineral admixture, characterized in that: The composition includes the following components by mass percentage: 8%-30% of early strength agent, 40%-70% of water-quenched blast furnace granulated slag, 10%-25% of water-quenched manganese slag, 5%-20% of first-grade fly ash and 5%-15% of ferrosilicon alloy dust removal ash; The early strength agent includes the following components: 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-aluminum fly ash and 20% desulfurization ash.

2. A method for preparing the solid waste-based early-strength concrete mineral admixture according to claim 1, characterized in that: The specific steps are as follows: Step S1. Prepare an early strength agent with a mass percentage of 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-aluminum fly ash and 20% desulfurization ash, then calcine the early strength agent and grind the calcined early strength agent to a powder specific surface area of ≥420m 2 / kg; Step S2: Grind the water-quenched blast furnace granulated slag and water-quenched manganese slag into powder respectively, with the powder specific surface area being ≥460m 2 / kg; Step S3. 8%-30% of an early strength agent, 40%-70% of water-quenched blast furnace granulated slag, 10%-25% of water-quenched manganese slag, 5%-20% of primary fly ash, and 5%-15% of ferrosilicon alloy dust ash are fully mixed according to mass fractions to prepare a solid waste-based early strength concrete mineral admixture.

3. The method for preparing a solid waste-based early-strength concrete mineral admixture according to claim 2, characterized in that: In step S1, the calcination temperature of the early strength agent is 1300° C.-1350° C.