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

Abstract

The invention discloses a solid waste based early strength type concrete mineral admixture and a preparation method thereof. The admixture comprises the following components 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 first-grade fly ash and 5%-15% of ferrosilicon dedusting ash. The early strength agent is composed of 35% of kaolin, 20% of anhydrous sodium sulphate, 8% of iron tailings, 7% of pulverized coal, 10% of high-alumina fly ash and 20% of desulfurized fly ash. The method comprises the following steps: preparing an early strength agent, calcining and grinding; secondly, grinding the water-quenched blast furnace granulated slag and the water-quenched manganese slag; and finally, mixing the components in proportion to obtain the admixture. According to the mineral admixture provided by the invention, multiple industrial solid wastes are organically combined and applied to concrete production, so that the early-stage and long-term strength and durability of concrete can be enhanced, the use amount of cement in the concrete is also greatly reduced, and the low-carbon development of the concrete industry is realized.

Description

Technical Field

[0001] The invention relates to the technical field of building material additives, and 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, the total carbon emissions in my country's construction sector reached 5.08 billion tons of CO2, accounting for 50.9% of the country's total carbon emissions, of which 2.82 billion tons of CO2 were generated in the production of building materials, accounting for the highest proportion and corresponding to about 30% of the country's total carbon emissions. Cement, as the dominant material, has a carbon emission of 1.23 billion tons of CO2, and 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 use 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, wherein the mineral admixture 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: A solid waste-based early-strength concrete mineral admixture comprises 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 primary fly ash and 5%-15% of ferrosilicon alloy dust removal ash.

[0006] Furthermore, the early strength agent includes the following components: 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-alumina fly ash and 20% desulfurization ash.

[0007] A method for preparing a solid waste-based early-strength concrete mineral admixture comprises the above-mentioned solid waste-based early-strength concrete mineral admixture, and the specific steps are as follows: Step S1. Prepare an early strength agent by preparing 35% by mass of kaolin, 20% of sodium sulfate, 8% of iron tailings, 7% of coal powder, 10% of high-aluminum fly ash and 20% 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; Step S2: Grind the water-quenched blast furnace granulated slag and the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥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.

[0008] Furthermore, in step S1, the calcination temperature of the early strength agent is between 1300°C and 1350°C.

[0009] The beneficial effects of the present invention are as follows: 1. The present invention utilizes kaolin, sodium sulfate, iron tailings, coal powder, high-aluminum fly ash, desulfurized ash, etc., whose main chemical components are Al, Ca, Si, S, etc., and whose main mineral components after calcination are dicalcium silicate and anhydrous calcium sulfate, etc., which are similar to the mineral composition of cement clinker, but the activity stimulation effect is better than that of silicate cement clinker. Therefore, it can be used as an early strength agent of mineral admixtures, thereby fully stimulating the gelling activity of silicon manganese slag and blast furnace water-quenched granulated slag, and generating stable CSH gel and CASH gel and AFt while reducing the amount of cement added in concrete. The amount of complex salt mineral generated in the hydration product is higher than the amount of hydration product generated by the replaced cement, making the hydration product particles finer, thereby improving the density of the interface reaction transition zone, and making the cementing network structure inside the concrete more compact. The mineral admixtures that do not participate in the reaction are gathered between the aggregate and the slurry, improving the weak regional structure, thereby improving the mechanical properties of the concrete.

[0010] 2. The present invention conducts physical and chemical dual stimulation on multiple industrial solid wastes, fully stimulates their gelling activity, and simultaneously realizes the morphological effect and micro-aggregate effect between material particles, which can effectively improve the working performance of concrete. The obtained concrete has good durability, low price, simple process, and is green and environmentally friendly.

[0011] 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 cement replacement amount in concrete can reach 50%-90%, which plays a significant role in reducing carbon emissions. The active minerals in the mineral admixture are mainly dicalcium silicate, which has 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 activity stimulation 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

[0012] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0013] A solid waste-based early-strength concrete mineral admixture, which 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.

[0014] 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%.

[0015] Example 1

[0016] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps: 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%, and 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.

[0017] Step S2: Grind the water-quenched blast furnace granulated slag and the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥460m 2 / kg; 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-class fly ash, and 5% of the ferrosilicon alloy dust removal ash according to the mass percentage, mix them thoroughly, and prepare the solid waste-based early strength concrete mineral admixture.

[0018] Example 2

[0019] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps: 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%, and 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.

[0020] Step S2: Grind the water-quenched blast furnace granulated slag and the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥460m 2 / kg; 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 removal ash according to the mass percentage of the raw materials, mix them thoroughly, and prepare the solid waste-based early strength concrete mineral admixture.

[0021] Example 3

[0022] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps: 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%, and 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 the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥460m 2 / kg; 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 removal ash according to the mass percentage, mix them thoroughly, and prepare the solid waste-based early strength concrete mineral admixture.

[0024] Example 4

[0025] The method for preparing a solid waste-based early-strength concrete mineral admixture in the present invention comprises the following specific steps: 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%, and 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.

[0026] Step S2: Grind the water-quenched blast furnace granulated slag and the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥460m 2 / kg; 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 removal ash according to the mass percentage, mix them thoroughly, and prepare the solid waste-based early strength concrete mineral admixture.

[0027] Experimental comparison demonstration 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 reducing agent 5.05 kg / m 3 .

[0028] Comparative Example 1 A common concrete mineral admixture is selected, wherein the admixture is composed of the following raw materials by mass fraction: 50% fly ash, 35% slag powder, and 15% steel slag powder, wherein the fly ash is Grade I ash in accordance with GB / T1596-2017 "Fly ash used in cement and concrete", the slag powder is Grade S95, and the powder specific surface area is 420 m 2 / kg, the specific surface area of ​​steel slag powder is 400m 2 / kg.

[0029] 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 reducing agent 5.05 kg / m 3 .

[0030] Comparative Example 2 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 / m3 , Polycarboxylate high efficiency water reducing agent 5.05 kg / m 3 .

[0031] Comparative Example 3 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 reducing agent 5.05 kg / m 3 .

[0032] Comparative Example 4 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 reducing agent 5.05 kg / m 3 .

[0033] Comparative Example 5 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 reducing agent 5.05 kg / m 3 .

[0034] The raw materials in Examples 1-4 and Comparative Examples 1-5 were placed in a concrete mixer and stirred evenly, injected into a 100mm×100mm×100mm mold at a temperature of 20±5°C and a relative humidity of not less than 60%, and placed on a concrete vibration table for vibration molding, and their related 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, and continued to be placed in a constant temperature and humidity curing box with a curing temperature of 20°C±2°C and a relative humidity of not less than 95% for curing to 3d and 28d ages, and 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 were tested. The above test results are shown in Table 1: Table 1 Test results 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 As can be seen from Table 1, the solid waste-based early-strength concrete mineral admixture of the present invention has a significant effect on improving the working performance, strength and durability of concrete, and its specific addition amount can be adjusted according to the concrete design parameters. The above specific embodiments are only preferred, but not limiting to the implementation methods.

[0035] In Example 3, the content of 50% 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.

[0036] In summary: the solid waste-based early-strength concrete mineral admixture provided by the present invention can replace a large amount of cement used in concrete, play a role in reducing carbon emissions, and at the same time improve the compressive strength and durability of concrete. Compared with various types of existing market, the solid waste-based early-strength concrete mineral admixture has the characteristics of high early strength and excellent durability, and has a significant gain effect, which well solves the problem of low early strength of concrete and affects construction.

[0037] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and 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 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 primary fly ash and 5%-15% of ferrosilicon alloy dust removal ash.

2. The solid waste-based early-strength concrete mineral admixture according to claim 1, characterized in that: The early strength agent comprises the following components: 35% kaolin, 20% sodium sulfate, 8% iron tailings, 7% coal powder, 10% high-aluminum fly ash and 20% desulfurization ash.

3. A method for preparing the solid waste-based early-strength concrete mineral admixture according to any one of claims 1 to 2, characterized in that: The specific steps are as follows: 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; Step S2: Grind the water-quenched blast furnace granulated slag and the water-quenched manganese slag into powders respectively, with a specific surface area of ​​≥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.

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